Clinical trial NCT04718961
Conditions: Intrahepatic Cholestasis of Pregnancy
Keywords: Pruritus Itch Itching Cholestasis Bile Acid Pregnancy Pregnant Intrahepatic Liver ICP
Sponsor: Mirum Pharmaceuticals, Inc.
Start date: 2021-01-04; Completion date: 2022-12-07
Enrollment: 4 participants; Allocation: RANDOMIZED; Intervention model: PARALLEL

Brief summary:
Part 1 is an open-label randomized study of volixibat in patients with Intrahepatic Cholestasis of Pregnancy (ICP) and elevated serum bile acid concentrations (sBA) to evaluate safety and tolerability of two doses of volixibat. Part 2 is a double-blind, placebo controlled, study designed to evaluate the safety and efficacy of a selected volixibat dose.

Detailed description:

Arms: arm 1: Participants randomized to this arm will receive volixibat 20mg twice daily. arm 2: Participants randomized to this arm will receive volixibat 80mg twice daily. arm 3: Participants randomized to this arm will receive volixibat selected dose (mg) twice daily. arm 4: Participants in this arm will receive capsules matched to the study drug minus the active volixibat substance, twice daily.
Interventions: intervention 1: Volixibat intervention 2: Placebo
Intervention descriptions: intervention 1: Oral capsules, administered twice daily. Volixibat is an ileal bile acid transporter (IBAT) inhibitor. intervention 2: Capsules matched to study drug minus active substance.

Protocol documents:
Prot_000.pdf: 
CONFIDENTIAL 
1 
E Title Page
 
PROTOCOL NUMBER: VLX-401 
Title: 
A Phase 2a/2b Randomized Double-Blind Placebo-Controlled Study to 
Evaluate the Efficacy and Safety of Volixibat in Adult Women with 
Intrahepatic Cholestasis of Pregnancy and Elevated Serum Bile Acid 
Concentrations (OHANA) 
Study Treatment: 
Volixibat (formerly SHP626, LUM002) 
Regulatory Agency Identifying Numbers: 
IND: 
147904 
EudraCT: 
2020-003448-96 
Phase: 
2a/2b 
Sponsor: 
Mirum Pharmaceuticals, Inc. 
950 Tower Lane 
Foster City, CA  94404 
Original Protocol 
Version 1, 14 October 2020 
Protocol History: 
Version 1 (United Kingdom), 4 December 2020 
Version 2, 18 May 2021 
Version 3, 7 October 2021 
Version 4, 20 April 2022 
 
 
This study will be performed in compliance with the International Council for Harmonisation Good Clinical 
Practices and applicable regulatory requirements, including the archiving of essential documents. 
 
This document contains confidential and proprietary information of Mirum and is disclosed pursuant to 
confidentiality and non-disclosure obligations.  This information should be used solely for the purposes for which it 
was provided and should not be copied, shared with, or disclosed to any third party without the express written 
consent of Mirum Pharmaceuticals, Inc. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
2 
INVESTIGATOR’S ACKNOWLEDGEMENT 
I have read this protocol for Mirum Pharmaceuticals, Inc., Study VLX-401, Version 4. 
Title:  A Phase 2a/2b Randomized Double-Blind Placebo-Controlled Study to Evaluate the 
Efficacy and Safety of Volixibat in Adult Women with Intrahepatic Cholestasis of Pregnancy 
and Elevated Serum Bile Acid Concentrations (OHANA) 
I have fully discussed the objectives of this study and the contents of this protocol with the 
sponsor’s representative. 
I understand that the information in this protocol is confidential and should not be disclosed, 
other than to those directly involved in the execution or the scientific/ethical review of the study, 
without written authorization from the sponsor.  It is, however, permissible to provide the 
information contained herein to a participant to obtain his or her consent (and/or assent when 
appropriate) to participate. 
I agree to conduct this study according to this protocol and to comply with its requirements, 
subject to ethical and safety considerations and guidelines, and to conduct the study in 
accordance with International Council for Harmonisation of Technical Requirements for 
Pharmaceuticals for Human Use (ICH) guidelines on Good Clinical Practice (GCP) and with the 
applicable regulatory requirements. 
I understand that failure to comply with the requirements of the protocol may lead to the 
termination of my participation as an investigator for this study. 
I understand that the sponsor may decide to suspend or prematurely terminate the study at any 
time for whatever reason; such a decision will be communicated to me in writing.  Conversely, 
should I decide to withdraw from execution of the study, I will communicate my intention 
immediately in writing to the sponsor. 
Investigator Name and Address: 
 
 
 
Signature: 
 
Date: 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
3 
TABLE OF CONTENTS 
INVESTIGATOR’S ACKNOWLEDGEMENT .........................................................................2 
TABLE OF CONTENTS ..............................................................................................................3 
1. 
PROTOCOL SUMMARY ................................................................................................9 
1.1. 
Synopsis .............................................................................................................9 
1.2. 
Study Schema...................................................................................................22 
1.3. 
Schedule of Activities ......................................................................................24 
LIST OF ABBREVIATIONS .....................................................................................................34 
2. 
INTRODUCTION............................................................................................................37 
2.1. 
Background on Intrahepatic Cholestasis of Pregnancy ...................................37 
2.2. 
Study Rationale ................................................................................................37 
2.2.1. 
Overview of Current Therapeutic Interventions and Rationale for Use 
of Volixibat in ICP ...........................................................................................39 
2.3. 
Volixibat Pharmaceutical and Therapeutic Background .................................40 
2.4. 
Key Nonclinical and Clinical Studies ..............................................................41 
2.5. 
Benefit/Risk Assessment .................................................................................42 
3. 
OBJECTIVES AND ENDPOINTS ................................................................................42 
3.1. 
Primary Objective and Endpoint ......................................................................42 
3.2. 
Secondary Objectives and Endpoints ...............................................................43 
3.3. 
Safety Objective and Endpoints .......................................................................44 
3.4. 
Exploratory Objectives and Endpoints ............................................................44 
4. 
STUDY DESIGN ..............................................................................................................46 
4.1. 
Overall Design .................................................................................................46 
4.2. 
End of Study Definition ...................................................................................47 
4.3. 
Scientific Rationale for Study Design ..............................................................47 
4.3.1. 
Overall Study Design .......................................................................................47 
4.3.2. 
Rationale for Endpoints ...................................................................................47 
4.3.3. 
Rationale for the Use of Comparator/Placebo .................................................51 
4.4. 
Justification for Dose .......................................................................................51 
5. 
STUDY POPULATION ..................................................................................................53 
5.1. 
Inclusion Criteria .............................................................................................53 
5.2. 
Exclusion Criteria ............................................................................................54 
5.3. 
Lifestyle Considerations ..................................................................................58 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
4 
5.4. 
Screen Failures .................................................................................................58 
5.5. 
Rescreening Considerations .............................................................................59 
5.6. 
Replacement Strategy ......................................................................................59 
6. 
TREATMENTS................................................................................................................59 
6.1. 
Investigational Product ....................................................................................59 
6.2. 
Dose Modification ...........................................................................................60 
6.3. 
Method of Treatment Assignment and Management .......................................61 
6.3.1. 
Randomization Procedures ..............................................................................61 
6.3.2. 
Interactive Response Technology for Study Drug Management .....................61 
6.4. 
Blinding............................................................................................................62 
6.5. 
Unblinding Study Drug Assignment ................................................................62 
6.6. 
Study Drug Accountability ..............................................................................62 
6.7. 
Participant and Treatment Compliance ............................................................63 
6.8. 
Concomitant Therapy.......................................................................................63 
6.8.1. 
Allowed Medications .......................................................................................64 
6.8.2. 
Prohibited Medications ....................................................................................65 
6.8.3. 
Treatment after End of Study ...........................................................................66 
7. 
DISCONTINUATION OF STUDY DRUG AND PARTICIPANT 
WITHDRAWAL CRITERIA .........................................................................................66 
7.1. 
Discontinuation of Study Drug ........................................................................66 
7.2. 
Participant Withdrawal from Study .................................................................67 
7.3. 
Lost to Follow-Up ............................................................................................67 
8. 
STUDY ASSESSMENTS AND PROCEDURES ..........................................................68 
8.1. 
Administration and General Procedures ..........................................................68 
8.1.1. 
Informed Consent.............................................................................................68 
8.1.2. 
Assignment of Participant Identification Number ...........................................68 
8.1.3. 
Inclusion/Exclusion Criteria ............................................................................68 
8.1.4. 
Demography .....................................................................................................68 
8.1.5. 
Prior and Concomitant Treatments ..................................................................69 
8.1.6. 
Medical, Menstrual, and Obstetric History ......................................................69 
8.1.7. 
Estimated Gestational Age Assessment ...........................................................69 
8.1.8. 
Screening Visit .................................................................................................69 
8.1.9. 
Baseline Visit ...................................................................................................69 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
5 
8.1.10. 
Randomization .................................................................................................70 
8.1.11. 
Study Drug Administration ..............................................................................70 
8.1.12. 
Management of Timing for Possible Elective Delivery ..................................70 
8.1.13. 
Delivery Visit ...................................................................................................70 
8.2. 
Efficacy Assessments .......................................................................................71 
8.2.1. 
Serum Bile Acids .............................................................................................71 
8.2.2. 
Adult ItchRO ....................................................................................................71 
8.2.3. 
Composite Adverse Perinatal Outcomes .........................................................71 
8.2.4. 
5-D Itch Scale ..................................................................................................72 
8.2.5. 
Clinician Scratch Scale ....................................................................................72 
8.2.6. 
EuroQoL 5-Dimension 5-Level .......................................................................72 
8.2.7. 
PROMIS SF v1.0-Fatigue 7a ...........................................................................72 
8.2.8. 
PROMIS SF v1.0-Sleep Disturbance ...............................................................72 
8.2.9. 
Patient Impression of Severity-Itch .................................................................73 
8.2.10. 
Patient Global Impression of Change-Itch .......................................................73 
8.2.11. 
Exploratory Markers of Bile Acid Synthesis, Inflammation, 
Pruritogens .......................................................................................................73 
8.3. 
Adverse Event Collection ................................................................................73 
8.3.1. 
Time Period for Collection ..............................................................................73 
8.4. 
Safety Assessments ..........................................................................................73 
8.4.1. 
Perinatal Assessment .......................................................................................74 
8.4.2. 
Fetal Ultrasound ...............................................................................................74 
8.4.3. 
Antepartum Fetal Monitoring ..........................................................................74 
8.4.4. 
Physical Examination.......................................................................................75 
8.4.5. 
Vital Signs ........................................................................................................75 
8.4.6. 
Fetal Heart Rate Confirmation .........................................................................75 
8.4.7. 
Clinical Laboratory Evaluations ......................................................................76 
8.4.8. 
Umbilical Cord Assessment .............................................................................76 
8.4.9. 
Drug and Alcohol Screen .................................................................................77 
8.4.10. 
Serology Screen ...............................................................................................77 
8.4.11. 
Coagulation Panel ............................................................................................77 
8.4.12. 
Lipid Panel .......................................................................................................77 
8.4.13. 
Glycated Albumin Evaluation..........................................................................77 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
6 
8.4.14. 
Fat-Soluble Vitamin Evaluation ......................................................................77 
8.4.15. 
Electrocardiograms ..........................................................................................78 
8.5. 
Pharmacokinetics .............................................................................................78 
8.6. 
Pharmacodynamics ..........................................................................................78 
8.7. 
Biomarkers .......................................................................................................78 
8.8. 
Genetics............................................................................................................78 
8.9. 
Healthcare Utilization ......................................................................................79 
9. 
SAFETY REPORTING...................................................................................................79 
9.1. 
Safety Parameters and Definitions ...................................................................79 
9.1.1. 
Adverse Events ................................................................................................79 
9.1.2. 
Serious Adverse Events ...................................................................................80 
9.2. 
Reporting and Follow-Up of AEs and/or SAEs ...............................................81 
9.2.1. 
AE and SAE Reporting ....................................................................................81 
9.2.2. 
Assessment of Intensity/Severity .....................................................................82 
9.2.3. 
Assessment of Causality ..................................................................................82 
9.2.4. 
Reference Safety Information ..........................................................................83 
9.2.5. 
Expedited Safety Reporting .............................................................................83 
9.2.6. 
Adverse Events of Special Interest ..................................................................83 
9.2.7. 
Events of Clinical Interest ................................................................................83 
9.2.8. 
Overdose and Special Reporting Situations .....................................................83 
9.2.9. 
Lactation/Exposure during Breastfeeding ........................................................85 
9.2.10. 
Follow-Up ........................................................................................................85 
10. 
STATISTICAL CONSIDERATIONS ...........................................................................85 
10.1. 
Sample Size Determination ..............................................................................86 
10.2. 
Population for Analyses ...................................................................................86 
10.3. 
Participant Disposition, Demographics, and Baseline Characteristics ............86 
10.4. 
Statistical Analyses ..........................................................................................86 
10.4.1. 
Efficacy Analyses ............................................................................................87 
10.4.2. 
Safety Analyses ................................................................................................95 
10.4.3. 
Other Analyses .................................................................................................97 
10.4.4. 
Interim Analysis ...............................................................................................98 
11. 
REGULATORY, ETHICAL, AND STUDY OVERSIGHT 
CONSIDERATIONS .......................................................................................................98 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
7 
11.1. 
Regulatory and Ethical Considerations ............................................................98 
11.2. 
Financial Disclosure .........................................................................................99 
11.3. 
Informed Consent Process ...............................................................................99 
11.4. 
Data Protection.................................................................................................99 
11.5. 
Committee Structure ......................................................................................100 
11.5.1. 
Independent Data Monitoring Committee .....................................................100 
11.6. 
Publication Policy ..........................................................................................100 
11.7. 
Dissemination of Clinical Study Data ............................................................100 
11.8. 
Data Quality Assurance .................................................................................100 
11.9. 
Study Monitoring ...........................................................................................101 
11.10. 
Audits and Inspections ...................................................................................102 
11.11. 
Institutional Review Board/Independent Ethics Committee ..........................102 
11.12. 
Data Handling and Recordkeeping ................................................................102 
11.12.1. 
Retention of Records ......................................................................................102 
11.12.2. 
Source Documents .........................................................................................102 
11.13. 
Study and Site Closure ...................................................................................103 
12. 
REFERENCES ...............................................................................................................104 
Appendix 1 
Clinical Laboratory Tests ...............................................................................110 
Appendix 2 
Genetics..........................................................................................................111 
Appendix 3 
Liver Safety:  Suggested Actions and Follow-Up Assessments ....................112 
Appendix 4 
Adult Itch Reported Outcome ........................................................................115 
Appendix 5 
5-D Itch ..........................................................................................................116 
Appendix 6 
Clinical Scratch Scale ....................................................................................118 
Appendix 7 
PROMIS® Fatigue and Sleep Modules ..........................................................119 
Appendix 8 
Patient Impression of Severity-Itch ...............................................................121 
Appendix 9 
Patient Global Impression of Change-Itch .....................................................122 
Appendix 10 
List of Known OATP2B1 Substrates .............................................................123 
Appendix 11 
Management of Clinical Study Procedures and Participants during 
COVID-19 Pandemic or Other Force Majeure ..............................................124 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
8 
LIST OF TABLES 
Table 1 
Schedule of Activities .................................................................................................24 
Table 2 
Allowed Medications and Therapies for Common Volixibat Side Effects ................64 
Table 3 
Analyses Populations ..................................................................................................86 
Table 4 
Perinatal Outcome Severity Scoring ...........................................................................94 
 
LIST OF FIGURES 
Figure 1 
Part 1:  Open Label (Proof of Concept) ......................................................................22 
Figure 2 
Part 2:  Double Blind (Confirmatory Analysis) ..........................................................23 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
9 
1. 
PROTOCOL SUMMARY 
1.1. 
Synopsis 
Name of Sponsor/Company: 
Mirum Pharmaceuticals, Inc. 
Name of Investigational Product: 
Volixibat  
Name of Active Ingredient: 
Volixibat potassium (formerly SHP626 and LUM002) 
Protocol Number:  VLX-401 
Title of Study:  A Phase 2a/2b Randomized Double-Blind Placebo-Controlled Study to Evaluate the 
Efficacy and Safety of Volixibat in Adult Women with Intrahepatic Cholestasis of Pregnancy and 
Elevated Serum Bile Acid Concentrations (OHANA) 
Study Centers:  This study will be conducted at multiple sites across Australia, New Zealand, North 
America, and the United Kingdom.  Other regions may be added. 
Participants: 
Up to 280 participants will be enrolled in this study.   
• 
Part 1 (open label):  Up to 80 participants with serum bile acid (sBA) ≥10 µmol/L during the 
screening period or at any time during the current pregnancy will be enrolled.  
• 
Part 2 (double blind):  Approximately 200 participants with a screening sBA level ≥20 μmol/L 
will be enrolled (100 per arm). 
Randomization: 
Part 1 (open label): 
• 
1:1 (volixibat 20 mg twice daily [BID]/volixibat 80 mg BID) 
Part 2 (double blind): 
• 
1:1 (selected volixibat dose BID/placebo BID) 
Randomization will be stratified according to background use of ursodeoxycholic acid (UDCA) or not 
(in Part 1), gestational age at randomization, presence/absence of gestational diabetes, and highest sBA 
levels before randomization (in Part 2). 
Study Period:  2020 to 2024 
Study Phase:  2a/2b 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
10 
Objectives and Endpoints 
Primary 
Part 1: 
• 
To assess the safety and tolerability of volixibat in participants with ICP on the basis of the 
following endpoints: 
o Proportion of participants experiencing one or more of the following: 
 
Treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), adverse 
events of special interest (AESIs), events of clinical interest (ECIs), and adverse events 
(AEs) that lead to discontinuation of study drug 
 
Clinically significant laboratory abnormalities 
Part 2: 
• 
To assess the efficacy of volixibat on the reduction of elevated sBA concentrations in participants 
with intrahepatic cholestasis of pregnancy (ICP) on the basis of the following endpoint: 
o Mean change from baseline to Week 3 of the treatment period in total sBA concentration  
Secondary 
The following secondary objectives and endpoints are applicable in Part 1 and Part 2. 
• 
To assess the efficacy of volixibat on pruritus due to ICP on the basis of the following endpoint: 
o Mean change from baseline to Week 3 of the treatment period in the weekly average worst 
daily itch score as measured by the Adult Itch Reported Outcome (ItchRO)   
• 
To assess the impact of volixibat on a composite perinatal outcome in participants with ICP on 
the basis of the following endpoints: 
o Proportion of participants experiencing one or more of the following: 
 
Perinatal death, defined as in utero fetal death after randomization or known neonatal 
death up to 28 days after birth 
 
Spontaneous preterm delivery, defined as delivery at <37 weeks’ gestational age 
following spontaneous onset of preterm labor or preterm premature rupture of the 
membranes (PPROM) 
 
Iatrogenic preterm delivery attributable to ICP or ICP-related complications, defined as 
delivery at <37 weeks’ gestational age resulting from medical intervention (i.e., 
augmentation/induction of labor or cesarean delivery without prior spontaneous onset of 
preterm labor or PPROM with one or more of the following as the indication for 
delivery): 
− 
Diagnosis of ICP with or without suspected fetal compromise 
− 
Persistently elevated/increasing sBA 
− 
Worsening hepatic function 
− 
Intolerable maternal ICP symptoms 
 
Neonatal unit admission for ≥12 hours from birth until hospital discharge for one or more 
of the following indications: 
− 
Respiratory insufficiency/failure with requirement for oxygen supplementation 
− 
Noninvasive or invasive respiratory support 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
11 
− 
Hemodynamic instability or shock requiring clinical intervention 
− 
Metabolic acidosis or signs of asphyxia 
− 
Proven infection 
− 
Hypoglycemia or feeding problems requiring intravenous (IV) fluids or tube feeding 
− 
Meconium-stained amniotic fluid and/or its sequelae (e.g., meconium aspiration, etc.) 
Safety 
• 
To assess the safety and tolerability of volixibat in participants with ICP on the basis of the 
following endpoints in Part 2: 
o Incidence of TEAEs, SAEs, AESIs, ECIs, and AEs that lead to discontinuation of study drug 
o Incidence of clinically relevant laboratory abnormalities 
Exploratory 
The following exploratory objectives and endpoints are applicable to Part 1 and Part 2: 
• 
To assess volixibat drug levels in maternal and fetal plasma and pharmacodynamic (PD) markers 
in maternal blood in participants with ICP on the basis of the following endpoints: 
o Volixibat concentrations in maternal and fetal plasma (from umbilical cord sampling) 
Note:  Assessment of maternal/fetal volixibat drug levels is a secondary objective for Part 1. 
o Change in biomarkers of bile acid synthesis, inflammation, and pruritogens 
o Proportion of participants with sBA <40 μmol/L at end of the treatment period 
• 
To assess the longer-term efficacy of volixibat in participants with ICP on the basis of the 
following endpoints: 
o Mean change from Week 3 to end of treatment period in total sBA concentration 
o Mean change from baseline to end of treatment period in total sBA concentration 
o Association between changes from baseline to Week 3 in total sBA and ItchRO as well as 
their association with the composite perinatal outcome 
• 
To assess the effect of volixibat on additional perinatal outcomes on the basis of the following 
endpoints: 
o Mean gestational age at delivery 
o Proportion of participants with an early term delivery (37–38 weeks 6 days, inclusive) 
o Proportion of participants with a full-term delivery (≥39 weeks) 
o Proportion of participants experiencing a perinatal death 
o Proportion of participants with a spontaneous preterm delivery 
o Proportion of participants with an iatrogenic preterm delivery attributable to ICP 
o Proportion of neonates requiring neonatal intensive care unit (NICU) admission for ≥12 hours 
between birth and hospital discharge 
o Proportion of neonates with meconium-stained amniotic fluid at delivery 
o Proportion of participants requiring rescue medication for ICP 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
12 
o Proportion of neonates with Apgar score <7 at 5 minutes of life  
o Mean birth weight percentile 
o Mean placental weight percentile 
o Proportion of neonates with umbilical cord pH <7.0 at birth 
o Means for umbilical cord blood sBA, total cholesterol, low-density lipoprotein cholesterol, 
and glucose 
o Mean maternal estimated blood loss at delivery 
o Mean time from randomization to delivery 
• 
To evaluate the effect of volixibat on additional measures of pruritus efficacy and quality of life 
in participants with ICP on the basis of the following endpoints: 
o Change from baseline in the 5-D Itch Scale 
o Change from baseline in Clinician Scratch Scale (CSS) 
o Change from baseline in EuroQoL 5-dimension, 5-level (EQ-5D-5L)  
o Change from baseline in Patient-Reported Outcomes Measurement Information System 
(PROMIS®) Short Form (SF) Fatigue 7a  
o Change from baseline in PROMIS SF Sleep Disturbance 
o Change from baseline in Patient Impression of Severity-Itch 
o Patient Global Impression of Change-Itch 
• 
To assess the impact of volixibat on healthcare utilization in participants with ICP on the basis of 
the following endpoints: 
o Number and duration of medical care encounters, including surgeries and other selected 
procedures (inpatient and outpatient) 
o Dates and duration of hospitalization (total days or length of stay, including duration by 
wards [e.g., intensive care unit]) 
o Number and type of diagnostic and therapeutic tests and procedures 
o Outpatient medical encounters and treatments (including physician or emergency department 
visits, tests and procedures, and medications) 
Study Design 
This is an operationally seamless adaptive clinical study that will consist of 2 parts.  Part 1 of the study is 
open label.  Part 2 of the study constitutes a randomized, double-blind, placebo-controlled phase 
comparing the selected volixibat dose with placebo for superior efficacy. 
Part 1: Proof of Concept, Safety/Tolerability, Dose Ranging, Pharmacokinetics, and Interim 
Analysis 
After a screening period of up to 10 days, eligible participants diagnosed with ICP with screening sBA 
≥10 µmol/L will be randomized with stratification (based on background use of UDCA or not, on 
gestational age [<32 weeks or ≥32 weeks] at randomization, and presence/absence of gestational diabetes) 
in a 2-arm (1:1), open-label fashion to receive volixibat 20 mg BID or volixibat 80 mg BID. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
13 
Study-drug dosing will begin on Day 0 and continue until end of the treatment period, defined as the day 
of delivery.  Study visits to assess safety, plasma concentrations of volixibat, pharmacodynamics, and 
efficacy will be conducted from baseline (Day 0) until delivery at time points specified in the protocol.  
Because alternative measures may be implemented when necessary for public health or other emergency 
situations, and when sufficient to help ensure the safety of study participants, some visits may be 
conducted as a home health or remote visit at the discretion of the investigator upon approval by the 
sponsor or designee and in accordance with local and regional regulations.  Participants will also enter 
ItchRO assessments into an electronic diary (eDiary) once daily (QD).  Use of limited rescue therapies for 
ICP will be permitted for participants who meet protocol-specified criteria. 
Part 2:  Confirmation of Safety and Efficacy with Selected Dose 
For Part 2, it is anticipated that ~200 participants (100 per arm) will be randomized after the volixibat 
dose is selected in Part 1. 
Participants with ICP with a screening sBA level ≥20 μmol/L who also meet the ItchRO criteria will be 
randomized with stratification (based on gestational age [<32 weeks or ≥32 weeks] at randomization, 
presence/absence of gestational diabetes, and highest sBA before randomization [<40 μmol/L, 
≥40 μmol/L to <100 μmol/L, or ≥100 μmol/L]) in a 2-arm (1:1), double-blind fashion to receive the 
selected volixibat dose BID or placebo. 
Study visits to assess safety, pharmacodynamics, efficacy, and plasma concentrations of volixibat in all 
participants will be conducted from baseline (Day 0) until delivery at time points specified in the 
protocol; sampling for volixibat concentrations may be discontinued in Part 2 if Part 1 results demonstrate 
consistently negligible or below the limit of quantification concentrations in maternal and umbilical cord 
(fetal) plasma.  Because alternative measures may be implemented, when necessary, for public health or 
other emergency situations and when sufficient to help ensure the safety of study participants, some visits 
may be conducted as a home health or remote visit at the discretion of the investigator upon approval by 
the sponsor or designee and in accordance with local and regional regulations.  Participants will also enter 
ItchRO assessments into an eDiary QD.  Use of limited rescue therapies for ICP will be permitted for 
participants who meet protocol-specified criteria. 
Safety 
In both Part 1 and Part 2, safety assessments will include AEs, clinical laboratory tests, vital signs, and 
physical examinations.  Additional fetal safety assessments will include serial ultrasounds to assess fetal 
growth and nonstress tests (NSTs)/cardiotocography (CTG) or fetal biophysical profile (BPP).  
Assessment of plasma concentrations of volixibat will be obtained in maternal plasma and umbilical cord 
plasma (when possible) at single time points, with no formal pharmacokinetic (PK) parameter analysis 
planned.  PD assessments will include bile acids alongside other biomarkers. 
In Part 1, ongoing monitoring of open-label safety data will be conducted by the sponsor at regular 
intervals per the medical and data monitoring plans as well as the routine safety surveillance activities, 
including but not limited to signal detection monitoring.  Additionally, a chartered, independent data 
monitoring committee (IDMC) will review unblinded maternal and fetal safety/plasma drug level data on 
an ongoing basis during this study (Part 2 only), with the initial IDMC meeting (post-study start) to be 
held after 12 participants in Part 2 complete the study; cadence for subsequent meetings will be outlined 
in the IDMC charter.  The sponsor plans to continue formal safety and efficacy monitoring via a chartered 
IDMC in Part 2; this will include AE monitoring specifications. 
End of Study 
The end of the study is defined as the date of the last visit of the last participant in the study.  The end of 
study for individual participants is the completion of the follow-up period after the day of delivery, 
including completion of follow-up Visit 2 (F2). 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
14 
Inclusion Criteria 
Participants who meet all of the following criteria will be eligible for the study: 
Informed Consent 
1. Provide signed informed consent as described in the protocol and be willing to comply with 
all study visits and requirements through end of study, including the follow-up period (F2) 
Age 
2. Female aged ≥18 and ≤45 years with viable pregnancy of 20 weeks 0 days or above: 
Part 1:  Singleton gestation and no more than 37 weeks 0 days (inclusive) or twin gestation 
and no more than 35 weeks 0 days (inclusive) at the baseline visit (Day 0) 
Part 2:  Singleton gestation and no more than 36 weeks 0 days (inclusive) at the baseline 
visit (Day 0) 
Note:  Confirmation of eligibility based upon estimated gestational age required per National 
Institute for Health and Care Excellence (NICE) guidelines before randomization:  
crown-rump length (CRL) from early ultrasound or head circumference on ultrasound if 
CRL >84 mm. 
Type of Participant and Disease Characteristics 
3. Diagnosis of ICP, as characterized by the following: 
Onset of pruritus during pregnancy with no known etiology other than ICP (e.g., pruritic 
urticarial papules and plaques of pregnancy, pruritic folliculitis, uncontrolled thyroid 
disease, etc.) 
sBA level ≥10 µmol/L at any point during the current pregnancy 
Absence of known pathology that may produce similar laboratory findings/symptoms; these 
include but are not limited to other cholestatic disorders, such as primary biliary cirrhosis 
(PBC) and primary sclerosing cholangitis (PSC) 
Note:  Suspicion of transient hypercholanemia should be discussed with medical monitor to 
confirm participants eligibility. 
4. Part 1: 
sBA of ≥10 µmol/L as assessed by the central laboratory during the screening period or 
local laboratory at any time during the current pregnancy   
Part 2: 
sBA level ≥20 μmol/L as assessed by the central laboratory during the screening period 
Documentation of historic or local sBA level is required to confirm participants eligibility 
before randomization.  
Laboratory assessments may be repeated at investigator’s discretion before randomization. 
Participants already on UDCA at the time of the screening visit shall be eligible for Part 1. 
5. Willing and able to refrain from the use of any of the following for the duration of the study:  
statins, rifampin, bile acid sequestrants (e.g., cholestyramine), peroxisome 
proliferator-activated receptor (PPAR) agonists/fibrate drugs (e.g., fenofibrate, bezafibrate), 
S-adenosyl methionine 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
15 
Participants requiring local/systemic corticosteroids or selective serotonin reuptake 
inhibitors (e.g., sertraline) for the management of non-cholestatic, non-pruritic conditions 
must have been on a stable dose for at least 1 week before screening and be willing to 
remain on a stable dose for the duration of the study to be considered eligible.  
Administration of isolated doses of corticosteroids for obstetric indications (e.g., promotion 
of fetal lung maturity for anticipated preterm delivery) is permitted. 
6. Part 2 only:  Willing and able to enter daily patient-reported outcome information in an 
eDiary for the duration of the study and completes ≥70% of the eDiary ItchRO assessments 
during the screening period.  A minimum of 4 once-daily ItchRO entries are required during 
screening. 
7. Part 2 only:  For the primary cohort only:  Qualified pruritus reflected by an average daily 
Adult ItchRO score ≥4 overall during the screening period 
Exclusion Criteria 
Any one of the following will exclude potential participants from eligibility for the study: 
Medical Conditions 
1. At the time of either the screening or baseline visit, decision has already been made to 
deliver within the next 7 days, for any indication 
2. Presence of triplets or higher multiple gestation, known placenta accreta, complete placenta 
previa, premature rupture of membranes (PROM) at any gestational age prior to 
randomization, cervical incompetence, history of prior spontaneous birth at ≤34 weeks not 
secondary to known or suspected ICP, or other condition (in the opinion of the 
investigator/medical monitor [refers to sponsor or contract research organization medical 
monitor throughout]) likely to result in spontaneous or iatrogenic delivery before 37 weeks 
3. Known non-reassuring fetal status based upon antepartum testing (e.g., NST/CTG or BPP) 
at or within 7 days before the baseline visit 
4. Known fetal anomaly likely to result in intrauterine fetal demise or neonatal death within the 
first 30 days of life 
5. History or evidence, with the exception of ICP, of current underlying cholestatic liver 
disease at screening or baseline, including but not limited to: 
• 
PSC or secondary sclerosing cholangitis (SSC) 
• 
PBC 
• 
Immunoglobulin G4-related cholangitis  
• 
Ascending cholangitis  
• 
Clinical evidence or suspicion of dominant strictures that are considered clinically 
relevant in the opinion of the investigator/medical monitor, or current or planned 
placement of percutaneous drain/biliary stent at screening 
6. Evidence of other hepatobiliary conditions at screening or baseline, including but not limited 
to: 
• 
Active hepatitis A infection 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
16 
• 
Active hepatitis B infection as defined by the presence of hepatitis B surface antigen or 
presence of hepatitis B virus DNA 
• 
Hepatitis C as defined by the presence of hepatitis C virus (HCV) antibody and positive 
HCV RNA.  Documented cured HCV infection is acceptable if >2 years earlier than the 
time of randomization 
• 
History or evidence of autoimmune hepatitis, Wilson disease, alpha-1-antitrypsin 
deficiency, hemochromatosis, or drug-induced liver disease (as defined on the basis of 
typical exposure and history).  A history of temporary, reversible cholestasis associated 
with medication use (e.g., hormones, antibiotics, etc.) is not exclusionary. 
• 
Evidence or clinical suspicion of cirrhosis, including decompensated cirrhosis (e.g., 
hepatic encephalopathy, portal hypertension, hepato-renal syndrome, hepato-pulmonary 
syndrome, esophageal varices, ascites) 
• 
Suspected or proven cholangiocarcinoma or hepatocellular carcinoma 
• 
History of liver transplantation 
• 
Confirmed or suspected nonalcoholic steatohepatitis as determined by the investigator 
• 
Acute fatty liver of pregnancy 
• 
Severe preeclampsia/hemolysis, elevated liver enzymes, and a low platelet count 
(HELLP) syndrome; suspected hemolytic anemia 
Note:  The presence of mild preeclampsia, gestational hypertension, or chronic 
hypertension is not considered exclusionary for study participation if the condition is 
adequately managed and there is no known plan for delivery within the next 7 days. 
• 
Alcohol-related liver disease 
• 
Known diagnosis of Gilbert syndrome 
Note:  The presence of gallstones or a prior history of cholecystectomy is NOT 
considered exclusionary. 
7. History or presence of known or suspected inflammatory bowel disease (e.g., Crohn’s, 
ulcerative colitis) 
8. History of small bowel resection or bariatric surgery (e.g., gastric bypass, banding, or 
sleeve), or surgery resulting in disruption of the enterohepatic circulation 
9. Part 2 only:  Presence of any concurrent underlying condition with unstable pruritus (e.g., 
unstable atopic dermatitis, psoriasis, urticaria, psychogenic pruritus, etc.) 
Note:  Participants with stable pruritic conditions (as above) that predate pregnancy and who 
have been on stable doses of treatment medications for the pruritic condition for ≥4 weeks 
before screening, may be considered eligible 
10. Anticipated need for liver transplantation within 12 months (365 days) after randomization 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
17 
11. Active infection that, in the opinion of the investigator or medical monitor, would preclude 
participation in the study for participant safety reasons 
Note:  An active COVID-19 infection (or recent infection within past 15 days) is considered 
exclusionary unless approved by the medical monitor. 
12. Unstable and/or serious medical disease that is likely to impair the participant’s ability to 
participate in all aspects of the study or result in substantially shortened life expectancy 
(e.g., malignancy, end-stage heart failure) 
13. Known diagnosis of HIV infection or HIV antibody positivity 
14. Clinically relevant alcohol use disorder or substance abuse within 12 months (365 days) 
before screening.  Alcohol use disorder for this study is defined as ≥2 standard drinks on 
average per day for women, with a standard drink defined as 1.5 oz (1 shot) of liquor, 5 oz 
of nonfortified wine, or 12 oz of beer (as defined by the National Institute of Alcohol Abuse 
and Alcoholism; 1 oz=29.57 mL). 
Diagnostic Assessments 
15. Participant has the following laboratory parameters at the screening visit, as determined by 
the central laboratory: 
• 
Platelet count ≤100,000/mm3 
• 
Serum creatinine ≥77 µmol/L (0.87 mg/dL) 
• 
AST or ALT ≥5 × ULN 
• 
Total bilirubin >1.3 mg/dL 
• 
INR >1.3 unless due to therapeutic anticoagulation 
16. Participant has evidence or preexisting history of atrial fibrillation, atrial flutter, complete 
bundle branch or heart block, Wolff-Parkinson-White syndrome, or other abnormality that is 
deemed clinically significant and/or likely to put participants at unacceptable risk to study 
participation, as determined by the investigator or the medical monitor. 
17. Except as defined elsewhere in the inclusion or exclusion criteria, abnormal laboratory 
results that are deemed to be clinically significant and put participants at unacceptable risk 
for study participation, as determined by the investigator or the medical monitor 
NOTE:  Investigators have the discretion to repeat assessments if they believe there is a reasonable 
possibility that the results were spurious or otherwise confounded.  Repeat assessments (no more than 
1 per laboratory parameter, under appropriate conditions) must be conducted within the screening period. 
Prior/Concomitant Therapy 
18. Use within 5 half-lives before randomization of any of the following medications: 
• 
Methotrexate 
• 
Sodium phenylbutyrate 
• 
PPAR agonists (e.g., fibrates) 
• 
Any investigational drug 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
18 
• 
Known hepatotoxins (e.g., cyclosporine, tacrolimus, Janus kinase [JAK] inhibitors 
[when dosed systemically], pancreatic lipase inhibitors [when dosed systemically], drugs 
[including any medicinal products, herbs, etc.] that are known to cause drug-induced 
liver injury [DILI] at the therapeutic labeled doses) 
19. Use within 5 half-lives before randomization of any of the following medications: 
• 
UDCA (Part 2 only; UDCA use is permitted in Part 1) 
• 
Rifampicin 
• 
Bile acid/lipid-binding resins (e.g., cholestyramine) 
• 
S-adenosylmethionine 
• 
Any other medications for the treatment of cholestasis – on- or off-label use 
20. Use within 5 half-lives before randomization of any of the following (when dosed 
systemically): 
• 
Progesterone supplementation 
• 
Cholestasis-inducing medications, including but not limited to erythromycin, 
amoxicillin-clavulanate, angiotensin-converting enzyme (ACE) inhibitors, or 
terbinafine, or prochlorperazine (Prochlorperazine USPI)  
21. Inability to tolerate antidiarrheal medications 
22. Previous use of an ileal bile acid transporter inhibitor 
Other Exclusions 
23. Breastfeeding at the time of the screening visit or planning to breastfeed at any time starting 
with the screening visit through end of the study treatment period 
24. Known intolerance/hypersensitivity to volixibat or its components 
25. Confirmed positive urine drug/alcohol screen at any time during pregnancy, including at the 
screening visit 
26. Participating in another ongoing interventional clinical study at screening or planning to 
participate in another contemporaneous interventional clinical study while participating in 
this study; contemporaneous participation in studies that do not involve pharmaceuticals, 
devices, or other interventions and do not interfere with this study’s (OHANA) schedule of 
activities (i.e., observational studies, registries) are permitted 
27. History of nonadherence to medical regimens, unreliability, medical condition, mental 
instability, or cognitive impairment that, in the opinion of the investigator or medical 
monitor, may interfere with the interpretation of study results, could compromise the validity 
of informed consent, compromise the safety of the participant, or lead to nonadherence with 
the study protocol or inability to conduct the study procedures 
28. Participant is in a dependent relationship with or has an immediate family member who is a 
study site employee that is involved in the conduct of this study (e.g., spouse, parent, child, 
or sibling) or participant is a study site employee. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
19 
Investigational Product, Dosage, and Mode of Administration 
Volixibat in capsules at doses of 20 mg and 80 mg and matched placebo will be supplied (in a blinded 
fashion for Part 2) for oral BID dosing.  As much as possible, the morning dose (4 capsules) will be 
administered ~30 minutes before breakfast and the evening dose (4 capsules) will be administered 
30 minutes before dinner to cover the luminal bile acid release associated with meals. 
Statistical Methods 
All predefined statistical analyses for the final analysis will be performed after the database is locked.  All 
statistical analyses will be performed using SAS software (SAS Institute, Cary, NC, USA) version 9.4 or 
higher. 
Primary Analysis for Primary Efficacy Endpoints 
The primary analysis on the primary efficacy endpoint will be conducted in Part 2 using the modified 
intent-to-treat (mITT) population.  A restricted maximum likelihood (REML)–based mixed-effects model 
for repeated measures (MMRM) will be used as the primary analysis method.  The repeated measures 
include weekly postbaseline visits through Week 3, with the change from baseline in total sBA as the 
dependent variable.  The MMRM model will include the fixed, continuous effects of baseline sBA and 
gestational age, fixed categorical effects of presence/absence of gestational diabetes, treatment group, 
visit, and treatment group-by-visit interaction and participant as a random effect. 
The primary efficacy analysis will compare volixibat and placebo using the contrast (difference in least 
squares [LS] means) between treatment groups at Week 3.  Significance tests will be based on LS means 
using a 2-sided significance level (2-sided 95% CIs). 
The null hypothesis for the primary efficacy endpoint of the equality of volixibat and placebo is: 
H0:  mean change in total sBA baseline and Week 3 in the 2 treatment groups are equal 
Separately, a similar analysis on each of the open-label cohorts will be performed.  The analysis will be 
identical, except that baseline sBA will not be a covariate used within the model. 
Secondary Efficacy Endpoint Analyses 
The secondary efficacy endpoints are designed to evaluate the efficacy of volixibat versus placebo for the 
treatment of pruritus in participants with ICP as well as composite perinatal outcomes. 
The secondary efficacy endpoint for pruritus is defined as the mean change from baseline to Week 3 in 
the weekly average worst daily itch score as measured by the Adult ItchRO.  The worst daily itch score is 
averaged over the 7 days preceding baseline and over the 7 days preceding each week through Week 3.  If 
>3 days of assessments are missing from a given week, then that weekly average will be set to missing.  
The analysis of the Adult ItchRO will use an MMRM with a comparable model to that for the primary 
endpoint.  The primary comparison will be made regardless of adherence to randomized treatment, 
treatment modification, or treatment termination and irrespective of any changes in, or initiations of, 
allowed concomitant therapies, while assuming prohibited medications are not available and that delivery 
or perinatal death prior to 3 weeks does not occur. 
The attributes for this estimand are the same as for the primary estimand except for the below: 
• 
Endpoint:  Change from baseline to Week 3 of the study treatment period in the weekly averaged 
worse daily itch score as measured by the Adult ItchRO (average of the 7 days preceding baseline 
and of the 7 days preceding Week 3). 
• 
Population-level summary:  Difference in the mean change in the weekly averaged worse daily 
itch score 
The secondary efficacy endpoint for composite perinatal outcomes is defined as the proportion of 
participants that experience any of the 4 outcomes specified in the protocol.  The comparison of interest is 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
20 
the proportion of participants meeting the composite outcome.  The primary comparison will be made 
regardless of adherence to randomized treatment, treatment modification, or treatment termination and 
irrespective of any changes in, or initiations of, allowed concomitant therapies, while assuming prohibited 
medications are not available. 
The attributes for this estimand are the same as for the primary estimand except for the below: 
• 
Treatments:  The randomized treatment administered BID until day of delivery (with at least 
1 dose), regardless of adherence to randomized treatment, treatment modification, or treatment 
termination. 
• 
Endpoint:  Experiencing one or more of perinatal death, spontaneous preterm delivery, iatrogenic 
preterm delivery attributed to ICP or ICP-related complications, neonatal unit admission for 
≥12 hours from birth until hospital discharge for one or more of predefined indications. 
• 
Population-level summary:  Difference between treatment groups in the proportion of participants 
achieving the endpoint. 
• 
Intercurrent events:  Preterm delivery or perinatal death are included as part of the endpoint 
definition and thus handled using a composite strategy. 
For this responder-type endpoint, the number and proportion of participants that are considered a 
“responder” will be summarized by treatment group at Week 3 and analyzed using a stratified 
Cochran-Mantel-Haenszel (CMH) test to calculate the p-value for the difference between treatment 
groups.  The p-value from the CMH test will be the basis of the hypothesis testing.  Furthermore, as 
supportive analyses, a Logistic Regression (LR) estimator approach, as well as a logistic regression model 
with baseline sBA, gestational age, and presence/absence of gestational diabetes as covariates will be run.  
All tests will be performed as 2-sided tests at the 0.05 level of significance. 
Safety Analyses 
All safety analyses will be performed on the safety population, defined as all participants who were 
randomized and received at least 1 dose of study medication. 
For all safety and tolerability analyses, participants will be analyzed by the treatment received and the 
overall active treatment group.  For active treatment, the dose received will be used.  
Safety data collected at the baseline visit or the last preceding visit (if not collected at the baseline visit) 
will be used as the baseline value for safety analyses. 
Safety measures include AEs, clinical laboratory values, physical examination findings (including body 
weight, height, and body mass index), vital signs, and concomitant treatment usage.  For quantitative 
variables, descriptive statistics including number of observations, mean, median, standard deviation, 
minimum, and maximum will be presented for observed and change from baseline values at each study 
visit.  Qualitative variables will be summarized using counts and percentages. 
Interim Analysis 
A formal interim analysis will be conducted at the end of Part 1, which will inform sample size for Part 2 
as well as dose selection.  There will be ongoing data review during Part 1 after every ~20 participants are 
enrolled in this open-label setting.  Data from Part 1 will be included in the overall safety and tolerability 
summaries but will not be combined with those from Part 2 for the statistical inference performed in 
Part 2. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
21 
Sample Size Determination 
Part 1 of the study is designed for estimation without formal statistical testing; hence, there are no formal 
power considerations.  For example, with 20 participants per group and assuming a standard deviation of 
25 for each group, a 95% CI for the mean for each volixibat arm would have a half width of 11.   
For the power calculations for Part 2, it is assumed that only a single dose will be selected at the end of 
Part 1, and a 2-sided alpha 0.05 will be used to test whether there is a difference between the 2 groups.  
Thus, for Part 2, a sample size of 100 participants per arm has 80% power to detect mean difference of 
10 with standard deviation of 25.  Power was calculated using SAS, version 9.4. 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
22 
1.2. 
Study Schema 
Figure 1 
Part 1:  Open Label (Proof of Concept) 
 
BID=twice daily; PK=pharmacokinetic; R=randomization; sBA=serum bile acid; VLX=volixibat. 
 
Estimated treatment duration 2-21 weeks per participant 
[ 
] 
~ 
level 2: IO µmol/L 
Screening 
1----------------➔
llt►I 
. 
. 
Up to 10 days 
N"' up to 80 
1: 1 
VLX80mgBID 
VLX20mgBID -·-·+ 
Interim a.nalysis to evaluate: 
• 
Safety & tolerability/PK (and 
possible early stopping for 
safety) 
• 
Dose exploration and selection of 
dose group based on benefit/risk 
• 
Efficacy (and futility analysis) 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
23 
Figure 2 
Part 2:  Double Blind (Confirmatory Analysis) 
 
PK=pharmacokinetic; QoL=quality of life; R=randomization; sBA=serum bile acid; VLX=volixibat. 
sBA ?::20 µmol/L 
Screening 
Up to 10 days 
Estimated treatment duration 2-21 weeks per participant 
1 :1 
- 200 
VLX Selected Dose 
Placebo (blinded) 
_ ,. 
Final analysis: 
.. 
Primary Endpoint 
• Change in sBA from baseline 
versus placebo 
Scconda.ry Endpoints 
• Safety/PK & tolerability 
• Pruritus measures 
• Assessment of adverse 
perinatal outcomes 
Additional endpoints 
• Serum markers of disease and 
pharmacodyoamics 
• Additional pruritus measures 
• Additional perinatal outcomes 
• QoL measures 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
24 
1.3. 
Schedule of Activities  
Table 1 
Schedule of Activities 
Visit Name 
Screening 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Weeks 1, 2, 3, 
etc. 
Early 
Termination* 
EOT/Delivery 
F1 
F2 (EOS) 
*Participants who early terminate 
from study drug should still continue 
with weekly visits through delivery, 
F1, and F2. 
Day/Week (Window) 
Day ‒10 to ‒1 
0* 
Every 7 Days 
(±1 Day) 
Until Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone Call: 
14 Days 
after 
Delivery 
(±3 Days) 
Clinic Visit: 
28 Days after 
Delivery 
(±3 Days) 
Some visits may be conducted as a 
home health or remote visit at the 
discretion of the investigator upon 
approval by the sponsor or designee 
and in accordance with local and 
regional regulations. 
*See Section 8.1.8 for further details 
on timing of baseline visit. 
Administrative Procedures 
Informed consent 
X 
 
 
 
 
 
 
 
Eligibility Procedures 
Inclusion/exclusion 
criteria 
X 
X 
 
 
 
 
 
 
Demography 
X 
 
 
 
 
 
 
 
Prior/concomitant 
treatment 
X 
X 
X 
X 
X 
X 
X 
 
Medical history 
X 
X 
 
 
 
 
 
Includes menstrual and obstetric 
history 
Estimated gestational 
age assessment 
X 
 
 
 
 
 
 
Confirmation of eligibility based 
upon estimated gestational age 
required before randomization:  
CRL from early ultrasound or head 
circumference on ultrasound if CRL 
is >84 mm. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
25 
Visit Name 
Screening 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Weeks 1, 2, 3, 
etc. 
Early 
Termination* 
EOT/Delivery 
F1 
F2 (EOS) 
*Participants who early terminate 
from study drug should still continue 
with weekly visits through delivery, 
F1, and F2. 
Day/Week (Window) 
Day ‒10 to ‒1 
0* 
Every 7 Days 
(±1 Day) 
Until Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone Call: 
14 Days 
after 
Delivery 
(±3 Days) 
Clinic Visit: 
28 Days after 
Delivery 
(±3 Days) 
Some visits may be conducted as a 
home health or remote visit at the 
discretion of the investigator upon 
approval by the sponsor or designee 
and in accordance with local and 
regional regulations. 
*See Section 8.1.8 for further details 
on timing of baseline visit. 
Hepatitis and HIV 
screen, TSH 
X 
 
 
 
 
 
 
If HIV results are documented as 
negative from the current pregnancy 
in a participant deemed to be low 
risk by the investigator, HIV at 
screening visit may be waived. 
Dosing Procedures 
Randomization 
 
X 
 
 
 
 
 
 
Study drug dispensing 
 
X 
X 
 
 
 
 
As needed  
Study drug collection/ 
reconciliation 
 
 
X 
X 
X 
 
 
As needed 
Efficacy Procedures 
Education and 
compliance assessment 
of pruritus assessments 
X 
X 
X 
 
 
 
 
Education regarding importance of 
eDiary compliance at screening 
visit; reinforcement regarding 
eDiary compliance at study visits (as 
needed). 
Once daily Adult 
ItchRO score 
assessment  
X 
X 
X 
X 
X 
 
 
Participant completes ItchRO at 
home on eDiary up to and including 
the day of delivery. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
26 
Visit Name 
Screening 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Weeks 1, 2, 3, 
etc. 
Early 
Termination* 
EOT/Delivery 
F1 
F2 (EOS) 
*Participants who early terminate 
from study drug should still continue 
with weekly visits through delivery, 
F1, and F2. 
Day/Week (Window) 
Day ‒10 to ‒1 
0* 
Every 7 Days 
(±1 Day) 
Until Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone Call: 
14 Days 
after 
Delivery 
(±3 Days) 
Clinic Visit: 
28 Days after 
Delivery 
(±3 Days) 
Some visits may be conducted as a 
home health or remote visit at the 
discretion of the investigator upon 
approval by the sponsor or designee 
and in accordance with local and 
regional regulations. 
*See Section 8.1.8 for further details 
on timing of baseline visit. 
Pruritus/QoL PRO 
assessments (5D itch 
scale, EQ-5D-5L, 
PROMIS SF 
v1.0-Fatigue 7a, 
PROMIS SF v1.0 - 
Sleep Disturbance, PIS-
Itch) 
X* 
X** 
X*** 
X 
X**** 
 
 
Participant completes at clinic. 
All PRO assessments to be 
completed by participant, including 
PIS-Itch and PGIC-Itch, should be 
collected prior to additional 
procedures at study visits.   
*Participant to complete paper 
PIS-Itch at screening.  This score 
will be captured in the EDC by site 
staff.  
** Participant may complete all the 
PRO assessments at home before 
they arrive onsite for the baseline 
visit (Day 0). 
*** At Week 3 visit only  
**** For participants who terminate 
from study drug early, this does not 
need to be repeated. 
PGIC-Itch 
 
 
X* 
X 
X** 
 
 
Participant completes at clinic. 
*At Week 3 visit only  
**For participants who terminate 
from study drug early, this does not 
need to be repeated. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
27 
Visit Name 
Screening 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Weeks 1, 2, 3, 
etc. 
Early 
Termination* 
EOT/Delivery 
F1 
F2 (EOS) 
*Participants who early terminate 
from study drug should still continue 
with weekly visits through delivery, 
F1, and F2. 
Day/Week (Window) 
Day ‒10 to ‒1 
0* 
Every 7 Days 
(±1 Day) 
Until Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone Call: 
14 Days 
after 
Delivery 
(±3 Days) 
Clinic Visit: 
28 Days after 
Delivery 
(±3 Days) 
Some visits may be conducted as a 
home health or remote visit at the 
discretion of the investigator upon 
approval by the sponsor or designee 
and in accordance with local and 
regional regulations. 
*See Section 8.1.8 for further details 
on timing of baseline visit. 
CSS 
 
X 
X* 
X 
X 
 
X 
To the extent possible, CSS 
assessments should be made by the 
same investigator or designee during 
study visits. 
*At Week 3 visit only.  
Other Procedures 
Health utilization 
 
X 
 
X 
 
 
X 
 
Safety Procedures 
Drug and alcohol 
screen 
X 
 
 
 
 
 
 
 
Physical examination 
X 
X 
X 
X 
X 
 
X 
Complete examination conducted at 
screening and F2 visits.  A 
symptom-directed examination 
focused on changes from last 
examination conducted at other 
visits.  Includes confirmation of fetal 
cardiac activity via 
Doppler/auscultation at each visit 
while participant is pregnant. 
Height 
X 
 
 
 
 
 
 
 
Weight 
X 
X 
X 
X 
X 
 
X 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
28 
Visit Name 
Screening 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Weeks 1, 2, 3, 
etc. 
Early 
Termination* 
EOT/Delivery 
F1 
F2 (EOS) 
*Participants who early terminate 
from study drug should still continue 
with weekly visits through delivery, 
F1, and F2. 
Day/Week (Window) 
Day ‒10 to ‒1 
0* 
Every 7 Days 
(±1 Day) 
Until Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone Call: 
14 Days 
after 
Delivery 
(±3 Days) 
Clinic Visit: 
28 Days after 
Delivery 
(±3 Days) 
Some visits may be conducted as a 
home health or remote visit at the 
discretion of the investigator upon 
approval by the sponsor or designee 
and in accordance with local and 
regional regulations. 
*See Section 8.1.8 for further details 
on timing of baseline visit. 
ECG 
X 
 
 
 
 
 
 
ECG is not a required study 
procedure; however, a local ECG at 
or after screening visit may be 
performed at the investigator’s 
discretion. 
Vital signs 
X 
X 
X 
X 
X 
 
X 
 
Hematology  
X 
 
X 
X 
X 
 
X 
 
Chemistry 
X 
 
X 
X 
X 
 
X 
 
Coagulation panel 
(PT/INR, PTT) 
X 
 
X 
X 
X 
 
X 
 
Vitamin A, D, and E 
levels 
 
X 
X* 
 
X 
 
X 
*Every 4 weeks, starting with 
Week 4 visit.  The sample collection 
tube should be protected from light. 
Urinalysis 
X 
X 
X 
X 
X 
 
X 
 
Lipid panel, glycated 
albumin 
X 
 
X* 
 
X 
 
X 
*Every 2 weeks, starting with 
Week 2 visit 
AE review 
 
X 
X 
X 
X 
X 
X 
AEs for mother and baby to be 
collected and reviewed for up to 
30 days after respective dates of 
hospital discharge.  See 
Section 8.3.1 for further details. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
29 
Visit Name 
Screening 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Weeks 1, 2, 3, 
etc. 
Early 
Termination* 
EOT/Delivery 
F1 
F2 (EOS) 
*Participants who early terminate 
from study drug should still continue 
with weekly visits through delivery, 
F1, and F2. 
Day/Week (Window) 
Day ‒10 to ‒1 
0* 
Every 7 Days 
(±1 Day) 
Until Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone Call: 
14 Days 
after 
Delivery 
(±3 Days) 
Clinic Visit: 
28 Days after 
Delivery 
(±3 Days) 
Some visits may be conducted as a 
home health or remote visit at the 
discretion of the investigator upon 
approval by the sponsor or designee 
and in accordance with local and 
regional regulations. 
*See Section 8.1.8 for further details 
on timing of baseline visit. 
Fetal ultrasound  
X* 
X* 
X** 
 
 
 
 
* First ultrasound may be done 
during screening OR baseline (both 
are not required).  The first study 
ultrasound (screening or baseline) 
may be waived if an ultrasound was 
already performed within 1 week 
prior to screening and should be 
captured in the eCRF on the 
screening ultrasound page. 
** Every 4 weeks while on study 
drug 
Antepartum fetal 
monitoring (NST/CTG 
or BPP) 
 
X 
 
 
 
 
 
At baseline visit only, and thereafter 
at the discretion of the investigator 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
30 
Visit Name 
Screening 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Weeks 1, 2, 3, 
etc. 
Early 
Termination* 
EOT/Delivery 
F1 
F2 (EOS) 
*Participants who early terminate 
from study drug should still continue 
with weekly visits through delivery, 
F1, and F2. 
Day/Week (Window) 
Day ‒10 to ‒1 
0* 
Every 7 Days 
(±1 Day) 
Until Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone Call: 
14 Days 
after 
Delivery 
(±3 Days) 
Clinic Visit: 
28 Days after 
Delivery 
(±3 Days) 
Some visits may be conducted as a 
home health or remote visit at the 
discretion of the investigator upon 
approval by the sponsor or designee 
and in accordance with local and 
regional regulations. 
*See Section 8.1.8 for further details 
on timing of baseline visit. 
Perinatal outcomes 
assessment 
 
 
 
 
X 
 
 
Outcomes include 
• 
Gestational age at delivery 
• 
Mode of delivery (e.g., vaginal, 
operative vaginal, Cesarean, 
etc.; and iatrogenic vs. 
spontaneous) 
• 
Indication(s) for delivery, if 
iatrogenic 
• 
Maternal estimated blood loss 
at delivery 
• 
Apgar score at 5 minutes 
• 
Infant/placenta weight  
• 
Presence/absence of meconium 
staining of amniotic fluid  
• 
Neonatal diagnoses and data, 
including NICU data if 
applicable 
Umbilical cord sample 
(at delivery, when 
possible) 
 
 
 
 
X 
 
 
Umbilical artery pH should be 
assessed first, followed by volixibat 
pharmacokinetics.  Thereafter, sBA, 
total cholesterol, LDL cholesterol, 
and glucose can be assessed in any 
order. 
Genetics – maternal 
blood (optional) 
 
X 
 
 
 
 
 
Specific testing TBD.  Must confirm 
specific consent has been obtained 
for genetic testing 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
31 
Visit Name 
Screening 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Weeks 1, 2, 3, 
etc. 
Early 
Termination* 
EOT/Delivery 
F1 
F2 (EOS) 
*Participants who early terminate 
from study drug should still continue 
with weekly visits through delivery, 
F1, and F2. 
Day/Week (Window) 
Day ‒10 to ‒1 
0* 
Every 7 Days 
(±1 Day) 
Until Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone Call: 
14 Days 
after 
Delivery 
(±3 Days) 
Clinic Visit: 
28 Days after 
Delivery 
(±3 Days) 
Some visits may be conducted as a 
home health or remote visit at the 
discretion of the investigator upon 
approval by the sponsor or designee 
and in accordance with local and 
regional regulations. 
*See Section 8.1.8 for further details 
on timing of baseline visit. 
Genetics – cord blood 
sample (optional) 
 
 
 
 
X 
 
 
Specific testing TBD.  Must confirm 
specific consent has been obtained 
for genetic testing. 
NICU admission  
 
 
 
 
X 
X 
X 
Collect NICU admissions diagnoses 
and data for the duration of NICU 
stay (i.e., follow to resolution). 
Drug Levels/Biomarkers Procedures 
Volixibat concentration 
sample (maternal 
plasma) 
 
 
X* 
X 
X 
 
 
*At Weeks 1 and 3 visit, 3 hours 
(±1 hour) post-dose  
When feasible, maternal sample 
should be collected as close to time 
of actual delivery as possible. 
Drug level sampling may be 
discontinued in Part 2 pending Part 1 
results 
Volixibat concentration 
sample (fetal plasma 
from umbilical cord at 
delivery, when 
possible) 
 
 
 
 
X 
 
 
Drug level sampling may be 
discontinued in Part 2 pending Part 1 
results 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
32 
Visit Name 
Screening 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Weeks 1, 2, 3, 
etc. 
Early 
Termination* 
EOT/Delivery 
F1 
F2 (EOS) 
*Participants who early terminate 
from study drug should still continue 
with weekly visits through delivery, 
F1, and F2. 
Day/Week (Window) 
Day ‒10 to ‒1 
0* 
Every 7 Days 
(±1 Day) 
Until Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone Call: 
14 Days 
after 
Delivery 
(±3 Days) 
Clinic Visit: 
28 Days after 
Delivery 
(±3 Days) 
Some visits may be conducted as a 
home health or remote visit at the 
discretion of the investigator upon 
approval by the sponsor or designee 
and in accordance with local and 
regional regulations. 
*See Section 8.1.8 for further details 
on timing of baseline visit. 
sBA 
X 
X* 
X* 
X 
X** 
 
X 
At each visit except EOT/Delivery, 
sBA should be drawn 30-90 minutes 
postprandially, whenever possible).  
Every effort should be made to 
collect sBA levels at approximately 
the same time of day (morning, 
midday, or afternoon) at each visit 
starting with baseline, except for 
EOT/delivery.  
*At baseline and Week 3, there will 
be 2 samples collected. 
**At EOT/Delivery, there will be 
2 samples collected, without regard 
to last meal. 
Postprandial biomarker 
samples (maternal)  
• 
7αC4 
(postprandial, 
30-90 minutes) 
• 
FGF-19  
• 
Autotaxin  
• 
Progesterone 
sulfate  
• 
GLP-1 
 
X 
X* 
 
X 
 
 
Prior to the sample collection, all 
participants are strongly encouraged 
to eat a meal within approximately 
30-90 minutes (whenever possible).  
Every effort should be made to 
collect biomarker sample collection 
at approximately the same time of 
day (morning, midday, or afternoon) 
at each visit. 
*At Week 3 visit only 
5-D Itch; Adult Itch RO; 7αC4=7α-hydroxy-cholesten-3-one; AE=adverse event; BPP=biophysical profile; CRL=crown rump length; CSS=Clinician Scratch Scale; 
CTG=cardiotocography; eCRF=electronic case report form; eDiary=electronic diary; EDC=electronic data capture; EOS=end of study; EOT=end of treatment; 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
33 
EQ-5D-5L=EuroQoL 5-Dimension 5-Level; ET=early termination; F1=Follow-Up Visit 1; F2=Follow-Up Visit 2; INR=international normalized ratio; ItchRO=Itch 
Reported Outcome; LDL=low-density lipoprotein; NICU=neonatal intensive care unit; NST=nonstress test; PGIC-Itch=Patient Global Impression of Change-Itch; 
PIS-Itch=Patient Impression of Severity-Itch; PRO=patient-reported outcome; PROMIS=Patient-Reported Outcomes Measurement Information System; PT=prothrombin 
time; PTT=partial thromboplastin time; QoL=quality of life; sBA=serum bile acid; SF=short form; TBD=to be determined; TSH=thyroid-stimulating hormone. 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
34 
LIST OF ABBREVIATIONS 
Abbreviation 
Definition 
7αC4 
7α-hydroxy-cholesten-3-one 
ACE 
angiotensin-converting enzyme 
AE 
adverse event 
AESI 
adverse event of special interest 
ANCOVA 
analysis of covariance 
BID 
twice daily 
BMI 
body mass index 
BPP 
biophysical profile 
Cmax 
maximum observed concentration 
CMH 
Cochran Mantel Haenszel 
CRL 
crown-rump length 
CRO 
contract research organization 
CSS 
Clinician Scratch Scale 
CTCAE 
Common Terminology Criteria for Adverse Events 
CTG 
cardiotocography 
DART 
developmental and reproductive toxicology 
DILI 
drug-induced liver injury 
ECI 
event of clinical interest 
eCRF 
electronic case report form 
eDiary 
electronic diary 
EQ-5D-5L 
EuroQol 5-dimension 5-level 
F2 
follow-up Visit 2 
fBA 
fecal bile acid 
GCP 
Good Clinical Practice 
GI 
gastrointestinal 
HBsAg 
hepatitis B surface antigen 
HCV 
hepatitis C virus 
IB 
Investigator’s Brochure 
IBAT 
ileal bile acid transporter 
ICF 
informed consent form 
ICH 
International Council for Harmonisation of Technical Requirements 
for Pharmaceuticals for Human Use 
ICP 
intrahepatic cholestasis of pregnancy 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
35 
Abbreviation 
Definition 
IDMC 
independent data monitoring committee 
IEC 
independent ethics committee 
INR 
international normalized ratio 
IRB 
institutional review board 
IRT 
interactive response technology 
ItchRO 
Itch Reported Outcome 
IV 
intravenous 
JAK 
Janus kinase 
LDL 
low-density lipoprotein 
LLOQ 
lower limit of quantitation 
LS 
least squares 
MAR 
missing at random 
medical monitor 
sponsor or CRO medical monitor 
MI 
multiple imputation 
mITT 
modified intent-to-treat 
MMRM 
mixed-effects model for repeated measures 
MNAR 
missing not at random 
NASH 
nonalcoholic steatohepatitis 
NICU 
neonatal intensive care unit 
NRS 
numerical rating scale 
NST 
nonstress test 
OR 
odds ratio 
PBC 
primary biliary cirrhosis 
PD 
pharmacodynamic 
PFIC 
progressive familial intrahepatic cholestasis 
PGIC-Itch 
Patient Global Impression of Change-Itch 
PIS-Itch 
Patient Impression of Severity-Itch 
PK 
pharmacokinetic 
PPAR 
peroxisome proliferator-activated receptor 
PPROM 
preterm premature rupture of the membranes 
PRO 
patient-reported outcome 
PROMIS® 
Patient-Reported Outcomes Measurement Information System 
PSC 
primary sclerosing cholangitis 
QD 
once daily 
QTcF 
QT interval corrected using Fridericia’s correction formula 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
36 
Abbreviation 
Definition 
RCOG 
Royal College of Obstetricians and Gynaecologists 
SAE 
serious adverse event 
SAP 
statistical analysis plan 
sBA 
serum bile acid 
SF 
Short Form 
SoA 
schedule of activities 
SOC 
System Organ Class 
TEAE 
treatment-emergent adverse event 
Tmax 
time to reach Cmax 
UDCA 
ursodeoxycholic acid 
WI-NRS 
Worst Itch Numeric Rating Scale 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
37 
2. 
INTRODUCTION 
2.1. 
Background on Intrahepatic Cholestasis of Pregnancy 
Intrahepatic cholestasis of pregnancy (ICP) is a rare cholestatic disorder that occurs during 
pregnancy and is associated with maternal changes in liver function, elevated levels of serum 
bile acids (sBAs), and intractable pruritus, as well as adverse perinatal outcomes (EASL 2009; 
Geenes and Williamson 2009; Williamson and Geenes 2014; Ozkan et al. 2015; 
Wood et al. 2018).  Cholestasis refers to an impairment of bile secretion and/or bile flow, which 
may clinically present with symptoms such as pruritus, fatigue, and jaundice and may be 
associated with changes in liver biochemistry markers.  Intrahepatic cholestasis is defined as 
cholestasis resulting from hepatocellular functional defects or obstructive lesions of the 
intrahepatic biliary tract distal from bile canaliculi. 
ICP is characterized by pruritus, which is frequently intense and intractable, with typical onset in 
the second or third trimester of pregnancy and elevated serum aminotransferases and sBA levels.  
ICP is also frequently associated with an abnormal maternal metabolic profile.  In addition to the 
hepatic features, there is an increased prevalence of dyslipidemia and impaired glucose tolerance 
in patients with ICP (Martineau et al. 2015).  Gestational diabetes and preeclampsia also occur 
more commonly in women with ICP (Goulis et al. 2004; Martineau et al. 2014).  After delivery, 
there is rapid (within a few weeks) resolution of signs and symptoms.  
ICP is also associated with an increased risk for adverse perinatal outcomes, including preterm 
birth and life-threatening or even fatal consequences for the fetus, such as stillbirth 
(Sepulveda et al. 1991; Williamson et al. 2001; Ovadia et al. 2019). 
Although ICP resolves rapidly following delivery, it is associated with an increased risk of future 
morbidity, including higher incidence of hepatobiliary diseases such as hepatitis, fibrosis, and 
gallstones and increased risk of liver and biliary tree cancer, immune-mediated disease, and 
cardiovascular disease.  Moreover, oral contraceptives, in particular those containing estrogens, 
may cause recurrence of symptoms, and guidelines recommend the use of alternative methods of 
contraception (Bicocca et al. 2018).  Furthermore, patients with ICP can suffer from jaundice or 
present with vitamin K deficiency, which can lead to prolonged coagulation time and increase 
the risk of intrapartum and postpartum hemorrhage (Mohan et al. 2019). 
Generally speaking, ICP is diagnosed if sBA levels are approximately ≥10 μmol/L in a pregnant 
woman with new onset of pruritus during pregnancy and no other known pathology thought to be 
responsible for the laboratory findings and/or symptoms (Bicocca et al. 2018).  ICP can be 
classified as mild or severe depending on the level of accumulation of sBA, with 40 μmol/L 
often used as the threshold value that is considered severe (Bicocca et al. 2018). 
2.2. 
Study Rationale 
The pathophysiology of ICP in the mother is incompletely understood; however, there is 
extensive clinical evidence that elevated maternal sBA levels are linked to maternal and fetal 
morbidity and mortality associated with ICP, suggesting that elevated maternal sBA plays a 
causal role in these adverse clinical outcomes (Sepulveda et al. 1991; Williamson et al. 2001; 
Glantz et al. 2004; Geenes et al. 2014; Mohan et al. 2019; Ovadia et al. 2019). 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
38 
The pathophysiology of adverse perinatal outcomes in ICP is likely related to the elevated sBA 
levels in the expectant mother (Ovadia et al. 2019).  In pregnancies uncomplicated by ICP, a 
physiologic sBA gradient across the placenta facilitates the disposal of fetal bile acids into the 
maternal blood stream, with ultimate elimination of both maternal and fetal bile acids via 
maternal feces (Monte et al. 1995).  However, in ICP, elevated sBA levels on the maternal side 
cause a reduction or reversal of the physiologic transplacental gradient, resulting in the 
accumulation of bile acids in the fetal compartment, as evidenced by the detection of elevated 
levels in amniotic fluid, cord serum, and meconium (Shaw et al. 1982; 
Geenes and Williamson 2009; Williamson and Geenes 2014).  Increased bile acid concentrations 
are associated with toxic effects, such as fetal cardiac arrhythmia and placental vessel spasms 
(Sepulveda et al. 1991; Williamson et al. 2001).  Such effects can have potentially life-
threatening or even fatal consequences for the fetus, and data from in vitro and animal studies 
support the role of elevated levels of bile acids in the promotion of preterm labor and the cause 
of the presence of meconium in the amniotic fluid, neonatal respiratory distress, and stillbirth 
(Geenes et al. 2014; Williamson and Geenes 2014).  Several cohort studies as well as recent 
systematic reviews with meta-analyses have clearly demonstrated the increased risk of adverse 
perinatal outcomes in ICP and their correlation with maternal sBA levels (Glantz et al. 2004; 
Geenes et al. 2014; Mohan et al. 2019; Ovadia et al. 2019): 
• The risk of stillbirth has been shown to increase in women with ICP who have sBA 
concentrations >100 μmol/L and increases as gestation progresses 
(Ovadia et al. 2019), suggesting a likely benefit from reduction of sBA promptly 
upon detection of elevated levels. 
• In a large prospective population-based case-control study performed in the United 
Kingdom, which included 669 women with severe ICP (sBA ≥40 μmol/L at any time 
during pregnancy) and a singleton pregnancy, a doubling in sBA level increased the 
risk of all preterm delivery by 68%, of spontaneous preterm delivery by 66%, of 
meconium staining of the amniotic fluid by 55%, and of stillbirth by 200% 
(Geenes et al. 2014). 
Increased bile acid concentrations appear to play a primary role in the development of the 
characteristic cholestatic pruritus associated with ICP, which is typically clinically significant, 
and in some cases is an indication to iatrogenic preterm delivery (Chappell et al. 2019).  The link 
is complicated by how specific hydrophilic and hydrophobic subspecies may interplay in 
pruritus.  It is possible, however, that a certain profile of sBA and/or pruritogen(s) is necessary to 
mediate pruritus (Bergasa 2014).  However, accumulation of bile acid as a result of cholestatic 
liver disease, including ICP, has been associated with pruritus, although direct correlation of sBA 
levels to severity of itch is debatable (Pathak et al. 2010; Kremer et al. 2012).  This association 
of sBA and pruritus is further supported by evidence from pregnancies in other cholestatic 
conditions.  In pregnant women with non-ICP–induced intrahepatic or extrahepatic cholestasis, 
such as primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC), respectively, 
in which systemic bile acid concentrations are typically elevated, similar maternal and fetal 
morbidity and mortality are observed (Efe et al. 2014; Patel et al. 2019).  Based on the collective 
data, the elevation of sBA plays a direct causal role on the characteristic maternal and fetal 
pathology of ICP. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
39 
2.2.1. 
Overview of Current Therapeutic Interventions and Rationale for Use of 
Volixibat in ICP 
Treatment of ICP is directed toward 2 main goals:  reducing symptoms in the expectant mother, 
in particular cholestatic pruritus, and reducing adverse perinatal outcomes. 
Off-label use of ursodeoxycholic acid (UDCA; except in France where it is approved for the 
treatment of ICP) has been the only option consistently proposed in guidelines as a treatment 
option for ICP.  However, evidence is mixed regarding its benefit.  Two Cochrane systematic 
reviews of the effectiveness of UDCA for ICP have concluded that it might ameliorate pruritus 
to a small extent but that definitive evidence for improvement in perinatal outcomes was absent 
(Gurung et al. 2013; Walker et al. 2020).  Additionally, a recent meta-analysis of 13 studies also 
concluded that UDCA did not significantly improve maternal or fetal outcomes 
(Shen et al. 2019).  In a recent double-blind, multicenter, randomized placebo-controlled study 
that enrolled 605 women with ICP in the United Kingdom (Chappell et al. 2019), UDCA was not 
effective in reducing a composite of adverse perinatal outcomes, defined as in utero fetal death or 
neonatal death, preterm delivery, or neonatal unit admission.  Although UDCA appeared to be 
safe, it had no clinically meaningful effect on maternal itch symptoms.  It did not reduce 
maternal sBA concentrations, and the reduction in ALT was of uncertain clinical significance.  In 
contrast to the randomized, placebo-controlled data from PITCHES, a recent individual patient 
data meta-analysis suggested that UDCA treatment in patients with ICP was associated with a 
statistically significant reduction in spontaneous preterm births in singleton pregnancies with 
initial sBA levels ≥40 μmol/L without a significant reduction in stillbirth, compared with no 
UDCA treatment (Ovadia et al. 2021).  Notably, the patients not treated with UDCA were treated 
with placebo, S-adenosyl-methionine, and/or other off-label therapies for ICP. 
In another small survey-based study, rifampicin use in combination with UDCA was associated 
with lower sBA levels in women with ICP (Geenes et al. 2015).  However, rifampicin treatment 
can be associated with hepatotoxicity, which affected up to 13% of participants in a study of 
PBC (Bachs et al. 1992), and the potential fetal side effects are unknown.   
Besides UDCA and rifampicin, cholestyramine, dexamethasone, and S-adenosyl-L-methionine 
have demonstrated some evidence of maternal benefit in ICP.  However, none of the 
aforementioned therapeutic options is considered as first-line treatment (EASL 2009; 
Tran et al. 2016; Bicocca et al. 2018).  Vitamin K supplementation is also frequently used in 
cases of vitamin K deficiency to limit the risk of intrapartum and postpartum hemorrhage.  
Temporary relief from pruritus may be achieved in some women through the use of 
over-the-counter topical treatments or antihistamines.  However, such therapeutic options 
provide limited and inconsistent relief and do not address the underlying pathologic mechanism 
of pruritus and the resulting potentially serious or fatal consequences for the fetus.  
In summary, UDCA use has shown limited and conflicting supporting evidence.  As a result, 
patients with ICP often cycle through UDCA and off-label therapies without relief, which may 
result in a decision to induce delivery preterm, increasing the risk of preterm-associated 
morbidity and mortality to the fetus (Chappell et al. 2019).   
Although recommendations are inconsistent across guidelines and the practice is not evidence 
based, active management of pregnancy by early elective delivery between 36 and 38 weeks is 
performed on a case-by-case basis in some regions of the world and seems to have been 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
40 
successful at reducing the intrauterine death rate (EASL 2009; Tran et al. 2016; 
Bicocca et al. 2018; ACOG 2019).  For example, a recent guidance from the Society for 
Maternal-Fetal Medicine (Lee et al. 2021) recommends elective delivery for patients with ICP 
and total sBA levels of <100 µmol/L between 36 weeks 0 days and 39 weeks 0 days of gestation; 
patients with total sBA levels ≥100 µmol/L should be offered delivery at 36 weeks of gestation.  
This practice is associated with its own risks for the baby, ranging from short-term neonatal 
problems to long-term issues such as cerebral palsy; disorders of psychological development, 
behavior, and emotion; and other major disabilities such as impaired vision and hearing 
(Moster et al. 2008; Saigal and Doyle 2008; MacKay et al. 2010; Quigley et al. 2012).   
In summary, although symptoms are transient for the mother, ICP is associated with increased 
maternal morbidity, increased risk of life-threatening or even fatal sequelae for the fetus, and 
chronically debilitating consequences for surviving infants.  This is reflected in the widespread 
policies to manage severe cases of ICP by elective early delivery between 36- and 38-weeks’ 
gestational age or earlier to reduce the risk of late stillbirth and alleviate maternal symptoms.  
This practice is not evidence based (EASL 2009; Tran et al. 2016; Bicocca et al. 2018; 
ACOG 2019) and is associated with potentially severe and/or chronic sequela. 
The current study is designed to assess the potential of volixibat to reduce maternal pruritus and 
fetal morbidity and mortality associated with ICP, which would provide a significant efficacy 
benefit over currently utilized therapies.  In ICP, lowering of (or mitigating potential further 
increases in) maternal sBA would be expected to ameliorate the increased risk of adverse 
perinatal outcomes associated with increased sBA levels by promoting restoration of the 
physiologic transplacental gradient and alleviating the accumulation of toxic bile acids in the 
fetus.  Given the evidence supporting the role of elevated sBA as a driver of adverse perinatal 
outcomes, the mean change in total maternal sBA concentration has been selected as the primary 
endpoint as a surrogate for clinically relevant perinatal outcomes.  Perinatal outcomes will also 
be directly assessed using a composite measure as a key secondary efficacy endpoint. 
The current study design is divided into 2 parts.  Part 1 is an open-label phase that provides 
real-time assessments of safety/tolerability of volixibat 20 mg and 80 mg as well as data for dose 
exploration and selection for Part 2 of the study.  Part 2 is a randomized, double-blind, 
placebo-controlled phase for confirmatory analysis comparing the selected volixibat dose with 
placebo for superior efficacy. 
2.3. 
Volixibat Pharmaceutical and Therapeutic Background 
Volixibat is an inhibitor of the ileal bile acid transporter (IBAT).  Inhibition of IBAT interrupts 
normal enterohepatic recirculation of bile acids, significantly increasing the amount of bile acid 
excreted in feces in treated participants and lowering circulating bile acid levels.  Bile acids and 
their recirculation are understood to be at the center of cholestatic pruritus pathophysiology, and 
IBAT inhibitors similar to volixibat, such as maralixibat and GSK2330672, have demonstrated 
efficacy in pruritus and sBA reductions associated with progressive familial intrahepatic 
cholestasis (PFIC), Alagille syndrome, PBC, and PSC (Hegade et al. 2017; 
Thompson et al. 2019; Bowlus et al. 2019; Gonzales et al. 2019a, 2019b; Mayo et al. 2019).  In 
nonclinical and clinical studies, treatment with volixibat has been shown to affect key 
pharmacodynamic (PD) parameters associated with IBAT inhibition, similar to other IBAT 
inhibitors.  These include increased fecal bile acid (fBA) excretion, in conjunction with increases 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
41 
in 7α-hydroxy-cholesten-3-one (7αC4) and decreases in low-density lipoprotein (LDL) 
cholesterol; both are PD measures indicating increased bile acid synthesis to compensate for 
increased bile acid excretion and a reduction in the bile acid pool in the body caused by effective 
IBAT inhibition. 
UDCA is used as a potential treatment for ICP despite evidence of limited efficacy (see 
Section 2.2.1).  The exact mechanism by which UDCA could provide benefit in ICP and other 
cholestatic diseases is not understood but could be due to its relatively hydrophilic nature 
compared with other bile acids.  While volixibat inhibits the recirculation of bile acids, it is 
important to note that no drug-drug pharmacokinetic (PK) interaction is expected between 
volixibat and UDCA.  The preferred substrates for IBAT are conjugated bile acids.  Since UDCA 
is a non-conjugated bile acid likely absorbed through passive diffusion, IBAT inhibition is not 
predicted to have an effect on the bioavailability of oral UDCA.  Published modeling of the 
pharmacokinetics of UDCA and its metabolites in the presence and absence of IBAT inhibition 
predicts the absence of a PK interaction (Zuo et al. 2016).  In addition, clinical UDCA PK data in 
the context of an IBAT inhibitor dosed in patients with PBC showed no drug-drug interaction 
between UDCA and the IBAT inhibitor (Hegade et al. 2017). 
A detailed description of the chemistry, pharmacology, efficacy, and safety of volixibat is 
provided in the Investigator Brochure (IB). 
2.4. 
Key Nonclinical and Clinical Studies 
This is the first study evaluating volixibat for the treatment of participants with ICP.  An 
extensive nonclinical PK; absorption, distribution, metabolism, and excretion (ADME); and 
safety package has been completed on volixibat, including a full battery of safety pharmacology 
studies, 4 different types of genotoxicity tests, and chronic general toxicity testing in rats (up to 
26-week duration) and in dogs (up to 39-week duration).  To prepare for the proposed ICP 
clinical study in the more vulnerable population of pregnant women, the battery of 
developmental and reproductive toxicology (DART) testing was also expanded, including 
fertility and early embryonic development testing in rats, embryo/fetal development testing in 
rats and rabbits, and prenatal and postnatal development testing (including maternal function) in 
rats.  No concerning toxicities were observed in any of these studies, and very large safety 
margins (14-160X depending on animal study, under the assumption of a human dose of 80 mg 
twice daily [BID]) were established between the animal doses and the highest proposed human 
dose. 
Volixibat is minimally absorbed after oral dosing at all doses tested.  The highest plasma 
concentration that has been recorded in previous clinical studies is 0.64 ng/mL (0.79 nM).  Food 
does not affect the absorption of volixibat.  Elimination is via fecal excretion with negligible 
metabolism and urinary excretion (70% eliminated in the feces within 24 hours, >90% from 
feces over the full course of a clinical mass balance study).  Metabolism and urinary excretion 
are negligible.   
Volixibat administration reduces systemic bile acids in all populations and species studied as 
evidenced by rapid and significant fecal excretion and consistent changes in markers indicative 
of an interruption of enterohepatic recirculation bile acids across healthy volunteers and 
participants with nonalcoholic steatohepatitis (NASH).  In addition, in instances where 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
42 
participants demonstrated elevated baseline levels of sBA, rapid and significant decreases in sBA 
were observed on volixibat treatment, consistent with the significant decreases in sBA observed 
in a nonclinical model of mild cholestasis.  The consistent PD effects of volixibat observed on 
bile acids and serum 7αC4 in previous clinical studies indicate that volixibat inhibits bile acid 
reabsorption and supports the potential utility in treating patients with ICP. 
Refer to the Volixibat IB for detailed information regarding nonclinical and clinical studies with 
volixibat. 
2.5. 
Benefit/Risk Assessment 
By virtue of volixibat’s ability to inhibit IBAT-mediated bile acid reabsorption, there is an 
increase in bile acid excretion via the intestine and feces that results in lower bile acid levels in 
the serum.  It is hypothesized that these net reductions in bile acid levels will, in turn, have a 
beneficial impact on pathological processes and symptoms in patients with diseases associated 
with elevated bile acid levels, such as ICP.  Volixibat has been well tolerated in clinical studies 
to date with the most common adverse events (AEs) being mild and transient gastrointestinal 
(GI) symptoms.  No clinically significant safety concerns were observed based on review of 
safety data across all participants exposed to volixibat.   
As stated above, clinical data suggest extremely low systemic exposure to volixibat, because it is 
minimally absorbed with concentrations obtained in humans at the intended clinical doses being 
typically below the lower limit of quantitation (LLOQ; LLOQ=0.05 ng/mL).  Taken together 
with the findings from the battery of DART testing, there is minimal risk of exposure to the fetus 
or harm to the fetus upon potential exposure to volixibat.  
Based upon the above, the benefit-risk profile of volixibat in patients with ICP, as well as in their 
neonates, is predicted to be favorable.  More detailed information about the known and expected 
benefits and risks, including the expected adverse reactions of volixibat, may be found in the 
Volixibat IB. 
3. 
OBJECTIVES AND ENDPOINTS 
The following objectives and endpoints will be evaluated in participants who meet study 
eligibility criteria.   
3.1. 
Primary Objective and Endpoint 
Part 1:  
• To assess the safety and tolerability of volixibat in participants with ICP on the basis of 
the following endpoints: 
o Proportion of participants experiencing one or more of the following: 
 Treatment-emergent adverse events (TEAEs), serious adverse events (SAEs), 
adverse events of special interest (AESIs), events of clinical interest (ECIs), and 
AEs that lead to discontinuation of study drug 
 Clinically significant laboratory abnormalities 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
43 
Part 2:  
• To assess the efficacy of volixibat on the reduction of elevated sBA concentrations in 
participants with ICP on the basis of the following endpoint:  
o Mean change from baseline to Week 3 of the treatment period in total sBA 
concentration  
3.2. 
Secondary Objectives and Endpoints 
The following secondary objectives and endpoints are applicable in Part 1 and Part 2.  
• To assess the efficacy of volixibat on pruritus due to ICP on the basis of the following 
endpoint: 
o Mean change from baseline to Week 3 of the treatment period in the weekly 
average worst daily itch score as measured by the Adult Itch Reported Outcome 
(ItchRO)  
• To assess the impact of volixibat on a composite perinatal outcome in participants 
with ICP on the basis of the following endpoints: 
o Proportion of participants experiencing one or more of the following: 
 Perinatal death, defined as in utero fetal death after randomization or known 
neonatal death up to 28 days after birth 
 Spontaneous preterm delivery, defined as delivery at <37 weeks’ gestational 
age following spontaneous onset of preterm labor or preterm premature 
rupture of the membranes (PPROM) 
 Iatrogenic preterm delivery attributable to ICP or ICP-related complications, 
defined as delivery at <37 weeks’ gestational age resulting from medical 
intervention (i.e., augmentation/induction of labor or cesarean delivery 
without prior spontaneous onset of preterm labor or PPROM with one or more 
of the following as the indication for delivery): 
- 
Diagnosis of ICP with or without suspected fetal compromise 
- 
Persistently elevated/increasing sBA 
- 
Worsening hepatic function 
- 
Intolerable maternal ICP symptoms 
 Neonatal unit admission for ≥12 hours from birth until hospital discharge for 
one or more of the following indications: 
- 
Respiratory insufficiency/failure with requirement for oxygen 
supplementation 
- 
Noninvasive or invasive respiratory support 
- 
Hemodynamic instability or shock requiring clinical intervention 
- 
Metabolic acidosis or signs of asphyxia 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
44 
- 
Proven infection 
- 
Hypoglycemia or feeding problems requiring intravenous (IV) fluids or 
tube feeding 
- 
Meconium-stained amniotic fluid and/or its sequelae (e.g., meconium 
aspiration, etc.) 
3.3. 
Safety Objective and Endpoints 
• To assess the safety and tolerability of volixibat in participants with ICP on the basis 
of the following endpoints in Part 2: 
o Incidence of TEAEs, SAEs, AESIs, ECIs, and AEs that lead to discontinuation of 
study drug 
o Incidence of clinically significant laboratory abnormalities 
3.4. 
Exploratory Objectives and Endpoints 
The following exploratory objectives and endpoints are applicable to Part 1 and Part 2: 
• To assess volixibat drug levels in maternal and fetal plasma and PD markers in 
maternal blood in participants with ICP on the basis of the following endpoints: 
o Volixibat concentrations in maternal and fetal plasma (from umbilical cord 
sampling) 
Note:  Assessment of maternal/fetal volixibat drug levels is a secondary objective 
for Part 1. 
o Change in biomarkers of bile acid synthesis, inflammation, and pruritogens  
o Proportion of participants with sBA <40 μmol/L at end of the treatment period 
• To assess the longer-term efficacy of volixibat in participants with ICP on the basis of the 
following endpoints: 
o Mean change from Week 3 to end of treatment period in total sBA concentration  
o Mean change from baseline to end of treatment period in total sBA concentration 
o Association between changes from baseline to Week 3 in total sBA and ItchRO as 
well as their association with the composite perinatal outcome 
• To assess the effect of volixibat on additional perinatal outcomes on the basis of the 
following endpoints:  
o Mean gestational age at delivery 
o Proportion of participants with an early term delivery (37–38 weeks 6 days, 
inclusive) 
o Proportion of participants with a full-term delivery (≥39 weeks) 
o Proportion of participants experiencing a perinatal death 
o Proportion of participants with a spontaneous preterm delivery 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
45 
o Proportion of participants with an iatrogenic preterm delivery attributable to ICP 
o Proportion of neonates requiring neonatal intensive care unit (NICU) admission 
for ≥12 hours between birth and hospital discharge 
o Proportion of neonates with meconium-stained amniotic fluid at delivery 
o Proportion of participants requiring rescue medication for ICP 
o Proportion of neonates with Apgar score <7 at 5 minutes of life  
o Mean birth weight percentile 
o Mean placental weight percentile 
o Proportion of neonates with umbilical cord pH <7.0 at birth 
o Means for umbilical cord blood sBA, total cholesterol, LDL cholesterol, and 
glucose 
o Mean maternal estimated blood loss at delivery 
o Mean time from randomization to delivery 
• To evaluate the effect of volixibat on additional measures of pruritus efficacy and quality 
of life in participants with ICP on the basis of the following endpoints: 
o Change from baseline in the 5-D Itch Scale 
o Change from baseline in Clinician Scratch Scale (CSS) 
o Change from baseline in EuroQoL 5-dimension, 5-level (EQ-5D-5L)  
o Change from baseline in Patient-Reported Outcomes Measurement Information 
System (PROMIS®) Short Form (SF) Fatigue 7a  
o Change from baseline in PROMIS SF Sleep Disturbance 
o Change from baseline in Patient Impression of Severity-Itch (PIS-Itch) 
o Patient Global Impression of Change-Itch (PGIC-Itch) 
• To assess the impact of volixibat on healthcare utilization in participants with ICP on the 
basis of the following endpoints: 
o Number and duration of medical care encounters, including surgeries and other 
selected procedures (inpatient and outpatient) 
o Dates and duration of hospitalization (total days or length of stay, including 
duration by wards [e.g., intensive care unit]) 
o Number and type of diagnostic and therapeutic tests and procedures 
o Outpatient medical encounters and treatments (including physician or emergency 
department visits, tests and procedures, and medications) 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
46 
4. 
STUDY DESIGN 
4.1. 
Overall Design 
This is an operationally seamless adaptive clinical study that will consist of 2 parts.  Part 1 of the 
study is open label.  Part 2 of the study constitutes a randomized, double-blind, 
placebo-controlled phase comparing the selected volixibat dose with placebo for superior 
efficacy.   
Part 1:  Proof of Concept, Safety/Tolerability, Dose Ranging, Pharmacokinetics, and 
Interim Analysis 
After a screening period of up to 10 days, eligible participants diagnosed with ICP with 
screening sBA ≥10 µmol/L will be randomized with stratification (based on background use of 
UDCA or not, on gestational age [<32 weeks or ≥32 weeks] at randomization, and 
presence/absence of gestational diabetes) in a 2-arm (1:1), open-label fashion to receive volixibat 
20 mg BID or volixibat 80 mg BID. 
Study-drug dosing will begin on Day 0 and continue until end of the treatment period, defined as 
the day of delivery.  Study visits to assess safety, plasma concentrations of volixibat, 
pharmacodynamics, and efficacy will be conducted from baseline (Day 0) until delivery at time 
points specified in the schedule of activities (SoA; Table 1).  Because alternative measures may 
be implemented when necessary for public health or other emergency situations, and when 
sufficient to help ensure the safety of study participants, some visits may be conducted as a home 
health or remote visit at the discretion of the investigator upon approval by the sponsor or 
designee and in accordance with local and regional regulations (Appendix 11; FDA 2020).  
Participants will also enter ItchRO assessments into an electronic diary (eDiary) once daily 
(QD).  Use of limited rescue therapies for ICP will be permitted for participants who meet 
protocol-specified criteria. 
Interim analyses are detailed in Section 10.4.4. 
Part 2:  Confirmation of Safety and Efficacy with Selected Dose 
For Part 2, it is anticipated that ~200 participants (100 per arm) will be randomized after the 
volixibat dose is selected in Part 1.  Participants with ICP with a screening sBA level 
≥20 μmol/L who also meet the ItchRO criteria (see Section 5.1) will be randomized with 
stratification (based on gestational age [<32 weeks or ≥32 weeks] at randomization, 
presence/absence of gestational diabetes, and highest sBA before randomization [<40 μmol/L, 
≥40 μmol/L to <100 μmol/L, or ≥100 μmol/L]) in a 2-arm (1:1), double-blind fashion to receive 
the selected volixibat dose BID or placebo. 
Study visits to assess safety, pharmacodynamics, efficacy, and plasma concentrations of 
volixibat in all participants will be conducted from baseline (Day 0) until delivery at time points 
specified in the SoA (Table 1); sampling for volixibat concentrations may be discontinued in 
Part 2 if Part 1 results demonstrate consistently negligible or below the limit of quantification 
concentrations in maternal and umbilical cord (fetal) plasma.  Because alternative measures may 
be implemented, when necessary, for public health or other emergency situations and when 
sufficient to help ensure the safety of study participants, some visits may be conducted as a home 
health or remote visit at the discretion of the investigator upon approval by the sponsor or 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
47 
designee and in accordance with local and regional regulations.  Participants will also enter 
ItchRO assessments into an eDiary QD.  Use of limited rescue therapies for ICP will be 
permitted for participants who meet protocol-specified criteria.  
Safety  
In both Part 1 and Part 2, safety assessments will include AEs, clinical laboratory tests, vital 
signs, and physical examinations.  Additional fetal safety assessments will include serial 
ultrasounds to assess fetal growth and nonstress tests (NSTs)/cardiotocography (CTG) or fetal 
biophysical profile (BPP).  Assessment of plasma concentrations of volixibat will be obtained in 
maternal plasma and umbilical cord plasma (when possible) at single time points, with no formal 
PK parameter analysis planned.  PD assessments will include bile acids alongside other 
biomarkers. 
In Part 1, ongoing monitoring of open-label safety data will be conducted by the sponsor at 
regular intervals per the medical and data monitoring plans as well as the routine safety 
surveillance activities, including but not limited to signal detection monitoring.  Additionally, a 
chartered, independent data monitoring committee (IDMC) will review unblinded maternal and 
fetal safety/plasma drug level data on an ongoing basis during this study (Part 2 only), with the 
initial IDMC meeting (post-study start) to be held after 12 participants in Part 2 complete the 
study; cadence for subsequent meetings will be outlined in the IDMC charter.  The sponsor plans 
to continue formal safety and efficacy monitoring via a chartered IDMC in Part 2; this will 
include AE monitoring specifications. 
4.2. 
End of Study Definition 
The end of the study is defined as the date of the last visit of the last participant in the study.  The 
end of study for individual participants is the completion of the follow-up period after the day of 
delivery, including completion of follow-up Visit 2 (F2). 
4.3. 
Scientific Rationale for Study Design 
4.3.1. 
Overall Study Design 
This is a randomized controlled study.  In Part 1, open-label dosing in both cohorts enables 
access to real-time unblinded safety/tolerability and PK data in participants who receive the 
20-mg or 80-mg doses of volixibat.  For Part 2, the double-blind design is adopted to minimize 
systematic bias.  Randomization eliminates bias and helps increase the homogeneity of 
participants across treatment groups. 
4.3.2. 
Rationale for Endpoints 
4.3.2.1. 
Efficacy Endpoints 
Mean Change from Baseline to Week 3 in Total sBA 
ICP is characterized by raised sBA levels.  According to Williamson and colleagues (2014), the 
most sensitive and specific marker for diagnosis of ICP is sBA level, in particular peak sBA 
levels that are strongly correlated with the risk of stillbirth and other adverse perinatal outcomes 
(Geenes et al. 2014; Ovadia et al. 2019).  Bile acids, the end products of hepatic cholesterol 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
48 
metabolism, are inherently cytotoxic.  In ICP, the transport of bile salts from the liver to the 
gallbladder is disrupted, resulting in the transport of bile salts from the hepatocytes into the 
blood. 
The fetal complications in ICP are thought to be related to high levels of bile acids in the fetal 
serum.  The fetus can synthesize bile acids from around 12 weeks of gestation; however, in ICP, 
some of the bile acids in the fetal compartment are derived from the mother.  In normal 
pregnancy, there is a transplacental gradient for bile acids that facilitates excretion of these toxic 
compounds from the fetus.  This gradient is reversed in ICP, leading to an accumulation of bile 
acids in the fetal serum and meconium.  A relationship between the maternal sBA level and 
adverse outcomes was found, establishing that for every 1- to 2-µmol/L increase in the bile acid 
level, there was a 1% to 2% increase in the risk of adverse outcome 
(Williamson and Geenes 2014). 
For participants with ICP, the reduction of sBA provides an opportunity to address both the 
significant burden of maternal pruritus as well as reduce the high rate of fetal morbidity and 
mortality.  Pharmacological inhibition of IBAT has demonstrated a reduction in sBA and pruritus 
across multiple clinical studies involving cholestatic liver diseases (Hegade et al. 2017; 
Thompson et al. 2019; Bowlus et al. 2019; Gonzales et al. 2019a, 2019b; Mayo et al. 2019).  
Evidence from other IBAT inhibitors in cholestatic diseases supports the rationale that volixibat 
has the potential to lower total sBA concentrations in women with ICP and impact pruritus and 
other comorbidities of ICP.  In clinical studies, volixibat demonstrated a consistent ability to 
reduce systemic bile acids, as evidenced by rapid and significant fecal excretion and consistent 
changes in markers, indicative of an interruption in the enterohepatic recirculation of bile acids.  
In Phase 1 studies, in instances where participants demonstrated elevated baseline levels of sBA, 
rapid and significant decreases were observed on volixibat treatment, consistent with findings 
from a nonclinical model of mild cholestasis. 
Peak sBA levels are associated with risk of adverse perinatal outcomes; for this reason, 
nonfasted (i.e., postprandial) sBA levels are clinically useful for monitoring ICP because they 
typically reflect higher levels compared with fasting values (Geenes et al. 2014; 
Oruc et al. 2014).  Collection of samples 30–90 minutes postprandially would be expected to 
capture peak serum levels in most patients (Lundasen et al. 2006).   
This study assesses the primary efficacy endpoint at 3 weeks because it is clinically relevant as a 
timeframe within which demonstrated efficacy of a drug for ICP will be important for clinical 
decision making.  In a large population-based, case-control study (Geenes et al. 2014), 
669 patients with a singleton pregnancy were identified within the UK Obstetric Surveillance 
System (UKOSS) as having severe ICP; the mean gestational age was 33 weeks 4 days at time of 
diagnosis in these patients.  Additionally, in a recent double-blind, multicenter, randomized 
placebo-controlled study that enrolled 605 women with ICP in the United Kingdom 
(Chappell et al. 2019), the median gestational age was 34.4 weeks at randomization.  With the 
mean/median gestational ages at diagnosis occurring between 33 and 34 weeks—and with Royal 
College of Obstetricians and Gynaecologists (RCOG) guidelines (2011) recommending 
consideration of elective delivery for patients with ICP after 37 weeks based on sBA-related 
risks of stillbirth—approximately 3 weeks of study drug treatment corresponds to a timeframe 
within which demonstration of sBA reduction is expected to be impactful for clinical decision 
making.  Furthermore, based on clinical experience with another IBAT inhibitor (maralixibat), 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
49 
continued improvements in sBA are likely to be seen with relatively longer treatment durations, 
arguing against analysis of sBA prior to the 3-week timeframe as a primary efficacy endpoint.  In 
Study LUM001-501, decreases in both sBA and ItchRO (observer) were observed at Week 2 and 
continued to decline even further at Week 4 in pediatric participants with non-truncating PFIC2, 
supporting the benefit of treatment durations >2 weeks for reduction of sBA and pruritus.  
However, given the mean/median gestational ages for ICP diagnosis (33–34 weeks), along with 
the requirement for randomization no later than 36 weeks 0 days in Part 2, participants are 
relatively more likely to be at the upper range of gestational age eligibility in this study, and as 
such, relatively few participants in this study will be expected to remain on treatment beyond 
3 weeks. 
Therefore, in addition to 3 weeks being a relevant timeframe for clinical decision making, 
assessment of the primary endpoint at 3 weeks of treatment is also expected to increase the 
likelihood of seeing a relatively larger treatment effect compared with assessment at 2 weeks, 
while keeping the number of participants with missing data to a reasonable minimum.  
Additionally, greater, statistically significant decreases in sBA and pruritus were seen in treated 
participants versus placebo at 2 weeks in a study of another IBAT inhibitor for a cholestatic 
indication (Hegade et al. 2017), supporting the likelihood of identifying a statistically significant 
treatment effect by 3 weeks in this study.  
Mean Change from Baseline to Week 3 in Adult ItchRO 
ICP is characterized by an intense, frequently intractable pruritus with typical onset in the second 
or third trimester of pregnancy, which negatively affects quality of life.  The associated pruritus 
may worsen at night, resulting in insomnia and additional fatigue; the maternal symptoms may 
also lead to iatrogenic preterm delivery with associated fetal morbidity/mortality.  
The Adult ItchRO consists of a daily eDiary; each eDiary is a single-item measure using an 
11-point numerical rating scale (NRS) from 0 (no itch) to 10 (worst possible itch), where higher 
scores indicate greater itch intensity.  The Adult ItchRO was originally developed and tested 
through concept elicitation and cognitive interviews with patients with PBC, a cholestatic disease 
with similarities to ICP in terms of clinical presentation of cholestatic pruritus 
(Boonstra et al. 2012).  Results of the cognitive debriefing demonstrated that patients understood 
the items, response options, and recall period used in the Adult ItchRO Worst Itch Numeric 
Rating Scale (WI-NRS).  The vast majority of patients interpreted the Adult ItchRO eDiary items 
as intended and all patients interpreted the response scale in the Adult ItchRO as intended. 
This initial study confirmed the content validity of the Adult ItchRO WI-NRS in patients with 
PBC, and literature has shown that pruritus is a relevant and defining symptom of ICP 
(Bacq et al. 1997; Bergman et al. 2013).  In addition, Adult ItchRO WI-NRS scales have been 
developed and used to support secondary endpoints for assessment of cholestatic itch 
(Hegade et al. 2017; Martin et al. 2019). 
Prior sponsors have used the Adult ItchRO as a secondary endpoint in previous studies of 
cholestatic itch in participants with PSC (Study LUM001-401; CAMEO study) and PBC 
(Study LUM001-201; CLARITY study); these data were used to evaluate the psychometric 
performance of the Adult ItchRO in participants with PBC and PSC.  Based on this assessment, 
the Adult ItchRO was found to be a reliable and valid measure that can detect small changes in 
pruritus, and the changes detected are clinically meaningful in patients with cholestatic liver 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
50 
diseases; therefore, the Adult ItchRO is anticipated to be a suitable endpoint for clinical studies 
investigating potential treatments for pruritus associated with ICP.   
The psychometric properties of the Adult ItchRO WI-NRS will be further evaluated in the ICP 
population as part of this study, as well as within a separately planned qualitative cognitive 
debriefing interview study including 15 additional patients with ICP.  This qualitative interview 
study will serve to further confirm content validity in the ICP population and will also collect 
patient feedback regarding meaningfulness of change in Adult ItchRO WI-NRS.  For further 
details of this instrument, refer to Section 8.2.3 and Appendix 4. 
In accordance with the rationale for timing of the primary efficacy endpoint, the sponsor will 
assess the key secondary efficacy endpoint at 3 weeks of treatment because it is clinically 
relevant for clinical decision making and data from other IBAT inhibitors support the likelihood 
of identifying a statistically significant treatment effect by 3 weeks in this study 
(Hegade et al. 2017).  Additionally, assessment at this time point is also expected to increase the 
likelihood of seeing a relatively larger treatment effect compared with assessment at 2 weeks, 
while keeping the number of participants with missing data to a reasonable minimum.  
Proportion of Participants with a Composite Adverse Perinatal Outcome 
The most devastating consequences of ICP are the associated adverse perinatal outcomes that 
may be life-threatening or even fatal to the fetus/infant in some cases.  These include an 
increased risk of preterm delivery (spontaneous and iatrogenic) as well as NICU admissions for 
fetal/neonatal asphyxia events, respiratory distress, meconium-stained amniotic fluid, and/or 
other conditions in which the infant’s status is severely compromised at or after birth.  In some 
cases, intrauterine fetal demise (stillbirth) occurs before delivery. 
In a recent aggregate meta-analysis, including 23 studies reporting on 5557 ICP pregnancies and 
165,123 control pregnancies (Ovadia et al. 2019), ICP was associated with a higher risk of 
spontaneous preterm birth (odds ratio [OR]:  3.47 [95% CI: 3.06, 3.95]) and iatrogenic preterm 
birth (OR:  3.65 [95% CI: 1.94, 6.85]), meconium-stained amniotic fluid (OR:  2.60 [95% CI: 
1.62, 4.16]), and admission to the neonatal unit or NICU (OR:  2.12 [95% CI: 1.48, 3.03]) 
compared with healthy pregnancies.  There is extensive clinical evidence that the risks of adverse 
perinatal outcomes are correlated with elevated maternal sBA levels, specifically in cases where 
sBA levels are ≥40 μmol/L (Sepulveda et al. 1991; Williamson et al. 2001; Glantz et al. 2004; 
Geenes et al. 2014; Mohan et al. 2019; Ovadia et al. 2019). 
Multiple outcomes may contribute significantly to the morbidity and/or mortality of the fetus and 
are correlated with elevated maternal sBA.  Therefore, a composite perinatal outcomes 
measurement will be used and is designed to encompass the most impactful adverse perinatal 
outcomes associated with ICP in a way that is both clinically meaningful and optimizes statistical 
power.  Because the expected rate of occurrence of any of the single event categories is expected 
to be too low to effectively power this study without an overwhelmingly large sample size, use 
of a composite endpoint can provide a substantially higher overall event rate, which allows 
adequate power with a more reasonable sample size.  In such situations, it is common to combine 
several events (e.g., a composite outcome of cardiovascular death, heart attack, and stroke, an 
approach frequently used in studies of cardiovascular drugs) in a “composite event endpoint” 
where the occurrence of any of the events would constitute an “endpoint event” (FDA 2017).  
This concept can be generally helpful in clinical development overall, and it is even more 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
51 
important when considering a clinical study involving pregnant participants to ascertain benefit 
while exposing as few participants to risk as possible.  
The composite endpoint is designed to capture the spectrum of primary adverse perinatal 
outcomes associated with ICP.  For further details of the specific components of this assessment, 
refer to Section 8.2.2. 
4.3.2.2. 
Safety Endpoints 
The safety assessments employed in this study, which include the incidence of TEAEs, SAEs, 
AESIs, ECIs, and AEs that lead to discontinuation, are widely used as measures to determine the 
overall safety profile and tolerability of a study drug. 
4.3.3. 
Rationale for the Use of Comparator/Placebo 
Placebo is used as the control to establish the frequency or magnitude of changes in clinical 
endpoints that could occur in the absence of active treatment. 
4.4. 
Justification for Dose 
The volixibat doses selected for this study have been determined based upon prior clinical 
experience with a range of oral doses between 0.5 mg QD and 80 mg BID, tested in multiple 
studies with healthy volunteers, obese/overweight participants, and participants with type 2 
diabetes mellitus and/or NASH for up to 48 weeks.  IBAT inhibitors have previously been 
demonstrated across multiple studies of cholestatic liver diseases to reduce sBA and pruritus in 
treated participants (Hegade et al. 2017; Mayo et al. 2019).  IBAT inhibition in the terminal 
ileum results in increased fBA excretion and decreased circulating sBA.  This results in a 
compensatory increase in hepatic bile acid synthesis, as reflected by increased levels of 
circulating 7αC4 (a bile acid precursor; Al-Dury and Marschall 2018).  Fasting 7αC4 
concentrations are a sensitive indicator of overall flux through the bile acid synthetic pathway 
and can be used to assess the degree of IBAT inhibition (Nunez et al. 2016). 
Based on results of a volixibat Phase 1 study (VLX-103) in healthy volunteers, although some 
interindividual variability was noted, a dose-dependent relationship in mean fasting 7αC4 levels 
was seen across the full range of doses studied (5–80 mg BID).  At Day 7 of volixibat dosing, 
higher doses of volixibat resulted in higher fasting 7αC4 concentrations:  the mean 7αC4 
concentration in the 80-mg BID cohort was 63% greater than in the 5-mg BID cohort, 44% 
greater than in the 20-mg QD cohort, 27% greater than in the 20-mg BID cohort, and 14% 
greater than in the 40-mg BID cohort.  Furthermore, at Day 17 of volixibat dosing, the 80-mg 
BID dose continued to demonstrate the highest fasting 7αC4 concentrations among all doses 
tested.  The dose dependency of 7αC4 suggests that higher doses are likely to result in greater 
reductions in sBA and pruritus due to dose-dependent effects on IBAT inhibition and 
interruption of enterohepatic circulation.  Based on the sponsor’s prior experience with IBAT 
inhibition in the Alagille syndrome clinical development program, higher doses of maralixibat 
indeed resulted in greater clinical reductions in sBA and pruritus, providing additional support 
for anticipated improved efficacy with higher doses of volixibat (Gonzales et al. 2019a, 2019b; 
Thompson et al. 2019). 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
52 
IBAT inhibition-related GI AEs are secondary to increased fBA excretion, resulting in increased 
free bile acid concentrations in the lower colon.  In patients with cholestatic liver disease, bile 
flow is reduced, and observations from ongoing programs with another IBAT inhibitor 
(maralixibat) in Alagille syndrome and PFIC have shown that the GI effects are generally mild 
and transient in nature in the setting of cholestasis.  It is anticipated that when used in ICP, 
volixibat will have a safety and tolerability profile similar to that of maralixibat for other 
cholestatic liver diseases (i.e., mild/transient GI effects).  Furthermore, since constipation is a 
very common symptom during pregnancy, it is anticipated that diarrhea associated with IBAT 
inhibition will likely be less frequent and less severe in patients with ICP compared with 
previously tested populations. 
No dose-dependent safety concerns were noted across the healthy volunteers in Study VLX-103; 
however, compared with lower doses, moderate volixibat-related cramping was noted more 
frequently at the 40-mg and 80-mg doses BID, although not in a dose-dependent fashion.  
Notably, no diarrhea or cramping AEs led to any study drug discontinuations in Study VLX-103, 
including at the 80-mg BID dose.  In conjunction with the dose-dependent 7αC4 increases, 
which suggest optimum IBAT inhibition at 80 mg BID compared with lower doses, these data 
support that 80 mg BID is an acceptable dose to be tested in Part 1 of Study VLX-401. 
At Day 7 of volixibat dosing in Study VLX-103, fBA excretion at the 20-mg BID dose was 
superior compared with fBA excretion at the 2 lower doses (5 mg BID and 20 mg QD); median 
fold increases in fBA excretion from baseline were 5.5 (5 mg BID), 2.1 (20 mg QD), 
11.7 (20 mg BID), 11.2 (40 mg BID), and 8.3 (80 mg BID).  In combination with the 7αC4 data, 
these data suggest that dosing below 20 mg BID is likely to result in a markedly inferior 
pharmacologic effect on reductions in sBA and pruritus while offering no benefit in terms of 
safety or tolerability because no marked differences in frequency/severity of (or discontinuations 
due to) GI AEs were noted in Study VLX-103 in the 5-mg BID or 20-mg QD cohorts compared 
with the 20-mg BID cohort.  Therefore, 20 mg BID is an appropriate lower boundary for initial 
doses to be tested in Part 1 of Study VLX-401. 
With regard to BID versus QD dosing, a prior volixibat study (SHP626-101) demonstrated 
improved fBA excretion with BID dosing compared with QD dosing for an equivalent daily 
exposure (i.e., mean fBA excretion was greater for 5 mg BID compared with 10 mg QD).  BID 
dosing provides greater coverage of IBAT over a 24-hour period, supporting the likelihood of 
relatively increased efficacy with a BID dosing schedule.  Based on modeling, predicted GI 
lumen concentrations of volixibat are expected to provide full IBAT inhibition for ~12 hours 
following a 20-mg dose; thus, 20 mg BID would be expected to provide 24-hour coverage of the 
IBAT transporter on average.  BID dosing has also been shown to result in greater treatment 
effects with another IBAT inhibitor, maralixibat, where improvements in sBA and pruritus were 
observed when the dose regimen was doubled from QD to BID in pediatric cholestasis. 
Based on available safety, tolerability, and PD data, and further supported by data demonstrating 
only sporadically detectable volixibat concentrations (with most below the LLOQ) in human 
plasma at the doses proposed, 20-mg BID and 80-mg BID are likely to represent an appropriate 
range of lower and higher dosages to study in Part 1 for treatment effects while being well 
tolerated and maintaining an acceptable safety profile in ICP for participants and fetuses.  
Although 20 mg BID and 80 mg BID are the initial dosages, a dose reduction of up to 75% of the 
original assigned dose, as outlined in Section 6.2, may also provide the opportunity for de facto 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
53 
exploration of 3 additional dosages (i.e., 5 mg BID, 10 mg BID, and 40 mg BID) in Part 1, 
should dose reductions be warranted for safety or tolerability considerations in some participants.  
Based upon thorough review of dose/exposure/response relationships for all doses explored in 
Part 1 at the interim analysis, an appropriate dose for Part 2 will be selected. 
5. 
STUDY POPULATION 
Participants must meet all inclusion criteria and no exclusion criteria at screening and at baseline 
(randomization).  Laboratory results that are qualifying at screening do not need to be repeated at 
the baseline visit unless specified in the SoA (Table 1).  
5.1. 
Inclusion Criteria 
Participants who meet all of the following criteria will be eligible for the study.  
Informed Consent 
1. Provide signed informed consent as described in Section 11.3 and be willing to 
comply with all study visits and requirements through end of study, including the 
follow-up period (F2) 
Age 
2. Female aged ≥18 and ≤45 years with viable pregnancy of 20 weeks 0 days or above.  
Part 1:  Singleton gestation and no more than 37 weeks 0 days (inclusive) or twin 
gestation and no more than 35 weeks 0 days (inclusive) at the baseline visit (Day 0)  
Part 2:  Singleton gestation and no more than 36 weeks 0 days (inclusive) at the 
baseline visit (Day 0)  
Note:  Confirmation of eligibility is based upon estimated gestational age required 
per National Institute for Health and Care Excellence (NICE) guidelines before 
randomization:  crown-rump length (CRL) from early ultrasound or head 
circumference on ultrasound if CRL >84 mm. 
Type of Participant and Disease Characteristics 
3. Diagnosis of ICP, as characterized by the following: 
Onset of pruritus during pregnancy with no known etiology other than ICP (e.g., 
pruritic urticarial papules and plaques of pregnancy, pruritic folliculitis, uncontrolled 
thyroid disease, etc.) 
sBA level ≥10 µmol/L at any point during the current pregnancy  
Absence of known pathology that may produce similar laboratory 
findings/symptoms; these include but are not limited to other cholestatic disorders 
such as PBC and PSC 
Note:  Suspicion of transient hypercholanemia should be discussed with medical 
monitor to confirm participants eligibility. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
54 
4. Part 1: 
sBA of ≥10 µmol/L as assessed by the central laboratory during the screening 
period or local laboratory at any time during the current pregnancy   
Part 2: 
sBA level ≥20 μmol/L as assessed by the central laboratory during the screening 
period 
Documentation of historic or local sBA level is required to confirm participant 
eligibility before randomization.  
Laboratory assessments may be repeated at the investigator’s discretion before 
randomization. 
Participants already on UDCA at the time of the screening visit shall be eligible for 
Part 1.   
5. Willing and able to refrain from the use of any of the following for the duration of 
the study:  statins, rifampin, bile acid sequestrants (e.g., cholestyramine), peroxisome 
proliferator-activated receptor (PPAR) agonists/fibrate drugs (e.g., fenofibrate, 
bezafibrate), S-adenosyl methionine 
Participants requiring local/systemic corticosteroids or selective serotonin reuptake 
inhibitors (e.g., sertraline) for the management of non-cholestatic, non-pruritic 
conditions must have been on a stable dose for at least 1 week before screening and 
be willing to remain on a stable dose for the duration of the study to be considered 
eligible.  
Administration of isolated doses of corticosteroids for obstetric indications (e.g., 
promotion of fetal lung maturity for anticipated preterm delivery) is permitted 
6. Part 2 only:  Willing and able to enter daily patient-reported outcome (PRO) 
information in an eDiary for the duration of the study and completes ≥70% of the 
eDiary ItchRO assessments during the screening period.  A minimum of 
4 once-daily ItchRO entries are required during screening. 
7. Part 2 only:  Qualified pruritus reflected by an average daily Adult ItchRO score ≥4 
overall during the screening period 
5.2. 
Exclusion Criteria 
Any one of the following will exclude potential participants from eligibility for the study: 
Medical Conditions 
1. At the time of either the screening or baseline visit, decision has already been made 
to deliver within the next 7 days, for any indication 
2. Presence of triplets or higher multiple gestation, known placenta accreta, complete 
placenta previa, premature rupture of membranes (PROM) at any gestational age 
prior to randomization, cervical incompetence, history of prior spontaneous birth at 
≤34 weeks not secondary to known or suspected ICP, or other condition (in the 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
55 
opinion of the investigator/medical monitor [refers to sponsor or contract research 
organization (CRO) medical monitor throughout]) likely to result in spontaneous or 
iatrogenic delivery before 37 weeks 
3. Known non-reassuring fetal status based upon antepartum testing (e.g., NST/CTG or 
BPP) at or within 7 days before the baseline visit 
4. Known fetal anomaly likely to result in intrauterine fetal demise or neonatal death 
within the first 30 days of life 
5. History or evidence, with the exception of ICP, of current underlying cholestatic 
liver disease at screening or baseline, including but not limited to: 
• PSC or secondary sclerosing cholangitis (SSC) 
• Primary biliary cholangitis (PBC) 
• Immunoglobulin G4-related cholangitis 
• Ascending cholangitis  
• Clinical evidence or suspicion of dominant strictures that are considered 
clinically relevant in the opinion of the investigator/medical monitor or current 
or planned placement of percutaneous drain/biliary stent at screening 
6. Evidence of other hepatobiliary conditions at screening or baseline, including but not 
limited to: 
• Active hepatitis A infection 
• Active hepatitis B infection as defined by the presence of hepatitis B surface 
antigen (HBsAg) or presence of hepatitis B virus DNA 
• Hepatitis C as defined by the presence of hepatitis C virus (HCV) antibody and 
positive HCV RNA.  Documented cured HCV infection is acceptable if >2 years 
earlier than the time of randomization 
• History or evidence of autoimmune hepatitis, Wilson disease, alpha-1-antitrypsin 
deficiency, hemochromatosis, or drug-induced liver disease (as defined on the 
basis of typical exposure and history).  A history of temporary, reversible 
cholestasis associated with medication use (e.g., hormones, antibiotics, etc.) is 
not exclusionary. 
• Evidence or clinical suspicion of cirrhosis, including decompensated cirrhosis 
(e.g., hepatic encephalopathy, portal hypertension, hepato-renal syndrome, 
hepato-pulmonary syndrome, esophageal varices, ascites) 
• Suspected or proven cholangiocarcinoma or hepatocellular carcinoma 
• History of liver transplantation 
• Confirmed or suspected NASH as determined by the investigator  
• Acute fatty liver of pregnancy 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
56 
• Severe preeclampsia/hemolysis, elevated liver enzymes, and a low platelet count 
(HELLP) syndrome; suspected hemolytic anemia  
Note:  The presence of mild preeclampsia, gestational hypertension, or chronic 
hypertension is not considered exclusionary for study participation if the 
condition is adequately managed and there is no known plan for delivery within 
the next 7 days.  
• Alcohol-related liver disease 
• Known diagnosis of Gilbert syndrome 
Note:  The presence of gallstones or a prior history of cholecystectomy is NOT 
considered exclusionary. 
7. History or presence of known or suspected inflammatory bowel disease (e.g., 
Crohn’s, ulcerative colitis) 
8. History of small bowel resection or bariatric surgery (e.g., gastric bypass, banding, 
or sleeve), or surgery resulting in disruption of the enterohepatic circulation  
9. Part 2 only:  Presence of any concurrent underlying condition with unstable pruritus 
(e.g., unstable atopic dermatitis, psoriasis, urticaria, psychogenic pruritus, etc.) 
Note:  Participants with stable pruritic conditions (as above) that predate pregnancy 
and who have been on stable doses of treatment medications for the pruritic 
condition for ≥4 weeks before screening may be considered eligible 
10. Anticipated need for liver transplantation within 12 months (365 days) after 
randomization 
11. Active infection that, in the opinion of the investigator or medical monitor would 
preclude participation in the study for participant safety reasons 
Note:  An active COVID-19 infection is considered exclusionary unless approved by 
the medical monitor. 
12. Unstable and/or serious medical disease that is likely to impair the participant’s 
ability to participate in all aspects of the study or result in substantially shortened life 
expectancy (e.g., malignancy, end-stage heart failure). 
13. Known diagnosis of HIV infection or HIV antibody positivity 
14. Clinically relevant alcohol use disorder or substance abuse within 12 months 
(365 days) before screening.  Alcohol use disorder for this study is defined as 
≥2 standard drinks on average per day for women, with a standard drink defined as 
1.5 oz (1 shot) of liquor, 5 oz of nonfortified wine, or 12 oz of beer (as defined by 
the National Institute of Alcohol Abuse and Alcoholism; 1 oz=29.57 mL). 
Diagnostic Assessments 
15. Participant has the following laboratory parameters at the screening visit, as 
determined by the central laboratory: 
• Platelet count ≤100,000/mm3 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
57 
• Serum creatinine ≥77 µmol/L (0.87 mg/dL) 
• AST or ALT ≥5 × ULN 
• Total bilirubin >1.3 mg/dL  
• INR >1.3 unless due to therapeutic anticoagulation 
16. Evidence or preexisting history of atrial fibrillation, atrial flutter, complete bundle 
branch or heart block, Wolff-Parkinson-White syndrome, or other abnormality that is 
deemed clinically significant and/or likely to put participants at unacceptable risk to 
study participation, as determined by the investigator or the medical monitor. 
17. Except as defined elsewhere in the inclusion or exclusion criteria, abnormal 
laboratory results that are deemed to be clinically significant and put participants at 
unacceptable risk for study participation, as determined by the investigator or the 
medical monitor. 
NOTE:  Investigators have the discretion to repeat assessments if they believe there is a 
reasonable possibility that the results were spurious or otherwise confounded.  Repeat 
assessments (no more than 1 per laboratory parameter, under appropriate conditions) must be 
conducted within the screening period. 
Prior/Concomitant Therapy 
18. Use within 5 half-lives before randomization of any of the following medications: 
• Methotrexate 
• Sodium phenylbutyrate 
• PPAR agonists (e.g., fibrates) 
• Any investigational drug 
• Known hepatotoxins (e.g., cyclosporine, tacrolimus, Janus kinase [JAK] 
inhibitors [when dosed systemically], pancreatic lipase inhibitors [when dosed 
systemically], drugs [including any medicinal products, herbs, etc.] that are 
known to cause drug-induced liver injury [DILI] at the therapeutic labeled doses) 
19. Use within 5 half-lives before randomization of any of the following medications: 
• UDCA (Part 2 only; UDCA use is permitted in Part 1) 
• Rifampicin 
• Bile acid/lipid-binding resins (e.g., cholestyramine) 
• S-adenosylmethionine 
• Any other medications for the treatment of cholestasis – on- or off-label use 
20. Use within 5 half-lives before randomization of any of the following (when dosed 
systemically): 
• Progesterone supplementation  


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
58 
• Cholestasis-inducing medications, including but not limited to erythromycin, 
amoxicillin-clavulanate, angiotensin-converting enzyme (ACE) inhibitors, 
terbinafine (Larson 2020), or prochlorperazine (Prochlorperazine USPI) 
21. Inability to tolerate antidiarrheal medications  
22. Previous use of an IBAT inhibitor 
Other Exclusions 
23. Breastfeeding at the time of the screening visit or planning to breastfeed at any time 
starting with the screening visit through end of the treatment period 
24. Known intolerance/hypersensitivity to volixibat or its components 
25. Confirmed positive urine drug/alcohol screen at any time during pregnancy, 
including at the screening visit 
26. Participating in another ongoing interventional clinical study at screening or 
planning to participate in another contemporaneous interventional clinical study 
while participating in this study; contemporaneous participation in studies that do 
not involve pharmaceuticals, devices, or other interventions and do not interfere with 
this study’s (OHANA) SoA (i.e., observational studies, registries) are permitted 
27. History of nonadherence to medical regimens, unreliability, medical condition, 
mental instability, or cognitive impairment that, in the opinion of the investigator or 
medical monitor, may interfere with the interpretation of study results, could 
compromise the validity of informed consent, compromise the safety of the 
participant, or lead to nonadherence with the study protocol or inability to conduct 
the study procedures. 
28. Participant is in a dependent relationship with or has an immediate family member 
who is a study site employee that is involved in the conduct of this study (e.g., 
spouse, parent, child, or sibling) or participant is a study site employee. 
5.3. 
Lifestyle Considerations 
There are no diet or activity restrictions for this study.  Alcohol use is strongly discouraged 
because there is no known amount of alcohol that can be safely consumed during pregnancy 
(CDC 2020). 
5.4. 
Screen Failures 
Screen failures are defined as participants who consent to participate in the clinical study but are 
not subsequently randomly assigned to study drug.  A minimal set of screen failure information 
is required to ensure transparent reporting of screen failure participants to meet the Consolidated 
Standards of Reporting Trials publishing requirements and to respond to queries from regulatory 
authorities.  Minimal information includes demography, screen failure details, eligibility criteria, 
and any SAE. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
59 
5.5. 
Rescreening Considerations 
Individuals who do not meet the criteria for participation in this study (screen failure) may be 
rescreened in the following situations: 
• Participant wishes to be rescreened upon reaching 18 years of age (Inclusion 
Criterion 2) 
• Participant’s first screening sBA level did not meet Inclusion Criterion 3 or 4 
• Participant had an active infection at screening but wants to rescreen after it has 
resolved (Exclusion Criterion 11) 
• Participant recently discontinued prohibited medication and wants to return after the 
relevant exclusionary timeframe has elapsed for rescreening (Exclusion Criterion 18, 
19, or 20) 
• Participant screen failed for other reasons, but the sponsor or designee approved 
rescreening 
• Part 2 only:  Participant failed to enter at least 70% of eDiary ItchRO assessments 
and at least 4 ItchRO scores during screening but wants to try again (Inclusion 
Criterion 6) 
• Part 2 only:  Participant had been on stable antipruritic medication(s) for a non-ICP 
pruritic condition for <4 weeks at first screening but wants to rescreen when it has 
been ≥4 weeks (Exclusion Criterion 9) 
Note:  For Part 2, participants who screen fail solely on the basis of Inclusion Criterion 7 (i.e., do 
not have average Adult ItchRO ≥4 overall during the screening period) will not be permitted to 
rescreen. 
If rescreening occurs within 3 weeks of previous screening, investigators have the option of 
repeating only hematology and chemistry, coagulation panel, fetal ultrasound, and perinatal 
assessment (repeat of urinalysis is optional).  For sBA, refer to Inclusion Criteria 3 and 4.  
Repeat of the following tests from the central laboratory for this study may be waived at 
rescreening (provided the results were within normal limits):  HIV, HBsAg, HCV antibody, 
TSH, drug and alcohol screening, vitamins A, D, and E, lipid panel, and/or glycated albumin. 
5.6. 
Replacement Strategy 
A participant who discontinues from study drug or withdraws from the study will not be 
replaced. 
6. 
TREATMENTS 
6.1. 
Investigational Product 
Volixibat in capsules at doses of 20 mg and 80 mg and matched placebo will be supplied (in a 
blinded fashion for Part 2) for oral dosing BID.  As much as possible, the morning dose 
(4 capsules) will be administered ~30 minutes before breakfast and the evening dose (4 capsules) 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
60 
will be administered 30 minutes before dinner to cover the luminal bile acid release associated 
with meals. 
The sponsor or designee will provide the investigator and site with additional investigational 
product information, including dosage form, packaging, storage conditions, and labeling in the 
Pharmacy Manual.  Volixibat may be provided as multiple capsules per dose.  The packaged 
study drug will be labeled in accordance with country and regional specific regulatory 
requirements, and supplies will be shipped in accordance with the Pharmacy Manual.   
6.2. 
Dose Modification 
If a participant experiences an SAE believed to be related to study drug or a Grade 3 AE believed 
to be related to study drug, temporary interruption of dosing should be considered; see 
Section 7.1 for additional information on situations requiring permanent discontinuation of study 
drug.  When possible, the medical monitor should also be notified within 24 hours after any 
treatment-related AE that is Grade ≥3.  Dose interruptions for Grade 1 or Grade 2 AEs, including 
diarrhea, may be permitted in limited situations if the investigator deems it medically appropriate 
(e.g., prolonged symptoms with no response to adjunctive treatment, intolerance of AEs to the 
point that participant is considering early termination from study, etc.).  In general, rechallenge 
(i.e., resumption of dosing) may be considered for an AE if an alternative cause for the event is 
discovered or the event has resolved or returned to baseline severity; any concerns regarding 
rechallenge should be discussed with the medical monitor.  If a participant experiences an SAE 
or a Grade 3 AE believed not to be related to study drug, temporary interruption of study drug or 
dose reduction may still be considered with medical monitor or sponsor designee approval. 
A dose reduction of up to 75% of the original assigned dose is permitted in a stepwise reduction.  
For example, if any one of the following criteria are met, a dose reduction of up to 50% is 
allowed and then another reduction to 25% of original dose level may occur: 
• ≥1 episode of treatment-related cramping/abdominal pain requiring an unscheduled 
visit for threatened preterm labor 
• Any treatment-related GI AE resulting in secondary dehydration and/or 
hospitalization 
• For any participant who complains of intolerability to study drug that results in 
consideration of withdrawal from study drug, a dose interruption or reduction should 
be offered prior to early discontinuation from treatment. 
• Dose reductions for events not meeting the above criteria are generally not 
recommended but may be permitted in limited situations with approval from the 
medical monitor.  
For Part 2, all dose modifications and rechallenges will be performed in a blinded manner.   
Upon satisfactory resolution of the event(s) driving the dose modification as deemed by the 
investigator, rechallenge with the original dose level may be considered.  All rechallenges must 
be approved by the medical monitor.  


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
61 
For any treatment-related GI AEs, such as diarrhea, investigators are strongly encouraged to 
initiate therapy, such as loperamide, before a dose reduction is considered for tolerability 
reasons.  Additional information on the management of diarrhea is provided in Section 6.8.1.1. 
All participants who experience related Grade ≥3 AEs shall be followed up via telephone and/or 
clinic visits (unscheduled if necessary) every 2–4 days until resolution.  If the participant’s 
clinical status worsens, study drug shall be discontinued. 
Additional information on the management of abnormal liver function tests, including criteria for 
potential dose interruption, is provided in Appendix 3. 
6.3. 
Method of Treatment Assignment and Management 
6.3.1. 
Randomization Procedures 
Individual participant treatment is automatically assigned by an interactive response technology 
(IRT) system.  
• For Part 1, participants will be randomized with stratification (based on background use 
of UDCA or not, gestational age [<32 weeks or ≥32 weeks] at randomization, and 
presence/absence of gestational diabetes) after confirmation of study eligibility in a 1:1 
ratio via a computer-generated randomization schedule to receive volixibat 20 mg BID or 
80 mg BID. 
• For Part 2, a dynamic allocation method, introduced by Pocock and Simon (1975) will be 
adopted to balance participant assignment between treatment arms based on the following 
factors:  gestational age (<32 weeks or ≥32 weeks) at randomization, presence/absence of 
gestational diabetes, and highest sBA before randomization (<40 μmol/L, ≥40 μmol/L to 
<100 μmol/L, or ≥100 μmol/L) after confirmation of study eligibility in a 1:1 ratio via a 
computer-generated randomization schedule to receive the selected volixibat dose 
(determined at the interim analysis) or placebo BID 
The participant’s randomization number represents a unique number corresponding to the 
treatment allocated to the participant. 
6.3.2. 
Interactive Response Technology for Study Drug Management 
An IRT system will be used for screening and enrolling participants, randomization, study drug 
supply dispensation and management, inventory management and supply ordering, study drug 
expiration tracking and management, and emergency unblinding.  Please refer to the study 
manual for additional details regarding the IRT. 
The investigator or designee will access the IRT at the screening visit (Visit 0) to record 
participant-specific information (i.e., unique participant number, age, etc.).  At the baseline visit 
(Visit 1), the investigator or designee will again access the IRT to either document a screen 
failure, or if the participant has met all entry criteria, to randomize the participant.  For 
randomized participants, the IRT will provide 1 or more bottle identification number(s) to 
dispense for treatment. 
A user manual with specific functions and instructions for the IRT will be provided to the site, 
and site personnel will be trained on its use. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
62 
6.4. 
Blinding 
Placebo capsules will contain compendial excipients that are commonly used in solid oral dosage 
formulations without the active API.  The placebo capsules visually match the active drug 
product.  To maintain the blind, all packaged study drug components will be identical. 
For Part 2, investigators will remain blinded to each participant’s assigned study drug throughout 
the course of the study.   
6.5. 
Unblinding Study Drug Assignment 
For Part 2, the treatment assignment must not be unblinded during the study except for expedited 
safety reporting and in emergency situations where the identification of the study drug is 
required for further treatment of the participant.  The investigator should make an effort to 
contact the medical monitor before emergency unblinding occurs or as soon as possible after the 
investigator has been unblinded without revealing the treatment assignment to the sponsor or 
designee.  In any event, the sponsor or designee must be informed about the code break as soon 
as possible. 
If the treatment assignment is unblinded, the date and the signature of the person who was 
unblinded and the reason for unblinding will be recorded in the source documents.  Upon 
breaking the blind in emergency situations, the participant will be withdrawn from study drug 
but should continue to be followed in the study for safety purposes as outlined in Section 7.1.  
Unblinding will be processed through the IRT vendor, and instructions will be available in the 
user manual. 
6.6. 
Study Drug Accountability 
Study drug will be dispensed at the study visits summarized in the SoA (Table 1).  Returned 
study drug will not be re-dispensed to participants. 
Investigators will be provided with sufficient amounts of the study drug to carry out this protocol 
for the agreed number of participants.  The investigator or designee will acknowledge receipt of 
the study drug, documenting shipment content and condition.  Accurate records of all study drug 
dispensed, used, returned, and/or destroyed must be maintained. 
The investigator has overall responsibility for dispensing study drug.  Where permissible, tasks 
may be delegated to a qualified designee (e.g., a pharmacist) who is adequately trained in the 
protocol and who works under the direct supervision of the investigator.  Study drug will be 
dispensed at baseline and at each visit in quantities sufficient for dosing at least until the next 
scheduled visit.  If necessary, direct-from-site to participant shipment of study drug is allowed 
between visits. 
The investigator or designee will dispense the study drug only to participants included in this 
study and following the procedures set out in the study protocol.  Each participant will be given 
only the assigned study drug.  All dispensed study drug will be documented in the IRT system. 
The investigator is responsible for ensuring the retrieval of all study supplies from participants.  
Participants must be instructed to bring their unused and empty or used study drug packaging to 
every visit.  Drug accountability must be assessed at the capsule level.  The pharmacist or 
designee will record details on the drug accountability form. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
63 
Other than study drug dispensed to participants, no stock or returned inventory may be removed 
from the site where originally shipped without prior knowledge and written consent by the 
sponsor.  If such transfer is authorized by the sponsor, all applicable local, state, and national 
laws must be adhered to for the transfer. 
The sponsor or its representatives must be permitted access to review the supply storage, 
distribution procedures, and records provided that the blind of the study is not compromised by 
such access. 
At the end of the study or as instructed by the sponsor, all unused stock, participant-returned 
study drug, and empty or used study drug packaging are to be returned or destroyed.  Study drug 
must be counted and verified by clinical site personnel and the sponsor (or designated clinical 
research organization) before return or destruction.  Shipment return or destruction forms must 
be completed before shipment from the site or destruction.  Shipment of all returned study drug 
must comply with local, state, and national laws. 
On the basis of entries in the site drug accountability forms/IRT, it must be possible to reconcile 
study drug delivered with those used and returned.  All study drugs must be accounted for, and 
all discrepancies investigated and documented to the sponsor’s satisfaction. 
The investigator or designee must confirm that appropriate temperature conditions have been 
maintained during transit for all study drug received and that any discrepancies are reported and 
resolved before use of the study drug. 
Only participants enrolled in the study may receive study drug, and only authorized site staff 
may supply or administer study drug.  All study drugs must be stored in a secure, 
environmentally controlled, and monitored (manual or automated) area in accordance with the 
labeled storage conditions, with access limited to the investigator and authorized site staff. 
Further guidance and information for the final disposition of unused study drug are provided in 
the study manual. 
6.7. 
Participant and Treatment Compliance 
Participant compliance with study procedures and treatment compliance will be assessed at each 
treatment visit by the site staff.  If a participant misses >25% of the assigned number of capsules 
weekly for 2 consecutive weeks because of non-safety related issues, investigators are 
encouraged to retrain the participant on treatment compliance before considering discontinuation 
from study treatment.  Any concerns with compliance should be discussed with the sponsor or 
designee. 
6.8. 
Concomitant Therapy 
Any medication or vaccine (including over-the-counter or prescription medicines, vitamins, 
and/or herbal supplements) that the participant is receiving at the time of screening or receives at 
any time during the study must be recorded, along with: 
• Reason for use 
• Dates of administration, including start and end dates 
• Dosage information, including dose and frequency 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
CONFIDENTIAL 
64 
Between at least 28 days before the screening visit and end of treatment, only those medications 
that are allowed (see Section 6.8.1) and are deemed necessary to maintain the participant’s health 
status are permitted for concomitant use.  The use of over-the-counter, dietary supplements, and 
herbal medications during study conduct is strongly discouraged, unless their use is considered 
necessary to maintain a participant’s current health status. 
The investigator is strongly encouraged to discuss the use of concomitant medications with the 
medical monitor before initiation of any medications, unless the participant requires immediate 
medical attention. 
Volixibat has the potential to inhibit the organic anion transporter OATP2B1 in the GI tract.  
This could potentially lower the plasma levels of orally administered drugs that are absorbed via 
the OATP2B1 transporter in the gut.  This should be considered before starting or continuing 
administration of drugs that are known substrates of this transporter.  See Appendix 10 for a list 
of known OATP2B1 substrates.  
6.8.1. 
Allowed Medications 
6.8.1.1. 
Concomitant Medications for Common Volixibat Side Effects 
Transient diarrhea, abdominal cramping, and/or nausea are commonly associated with IBAT 
inhibitors, such as volixibat.  Given the importance of minimizing premature discontinuations to 
maintain study integrity, every effort should be made to treat these typically transient symptoms 
before resorting to discontinuation of study drug.  Participants are strongly encouraged to take 
approved medications for GI symptoms (i.e., antidiarrheals, antiemetics, abdominal discomfort, 
etc.) as outlined in Table 2; in the event inadequate relief is obtained with allowed medications, 
the medical monitor should be consulted regarding potential other options that may be permitted. 
An investigator or obstetrician’s clinical judgment should be used to determine whether 
abdominal cramping or discomfort warrants prompt evaluation to rule out threatened preterm 
labor or other possible obstetric complications. 
Table 2 
Allowed Medications and Therapies for Common Volixibat Side Effects 
Indication 
Allowed Medications and Therapies 
Diarrhea 
Loperamidea, over-the-counter soluble fiber supplements (e.g., 
methylcellulose, psyllium) 
Nauseab 
Pyridoxine, metoclopramide, ondansetron 
Abdominal cramping/discomfort 
Oral hydration 
a 
Prompt use of loperamide is strongly encouraged if participant experiences 
gastrointestinal-related adverse events, such as diarrhea. 
b 
Many other antiemetics have antihistaminic properties, which may confound pruritus 
assessments.  In the event of inadequate relief with allowed antiemetics in this table, the 
medical monitor should be consulted, when possible, prior to initiating other antiemetic 
therapies.   


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
65 
6.8.1.2. 
Rescue Medication 
Use of the following medications may be considered as “rescue” for the treatment of worsening 
ICP, only under limited circumstances and after discussion with the medical monitor: 
• Antipruritics (antihistamines or topical antipruritics, such as menthol, pramoxine, or 
corticosteroids) 
• UDCA – for participants who were not on UDCA at screening, or an increase in dose 
for participants in Part 1 (who were on a stable dose of UDCA at screening) 
Whenever possible, the use of concomitant rescue medications should not be initiated for at least 
3 weeks after the initiation of study drug.  The following criteria may be considered in making 
decisions regarding initiation of rescue medication: 
• For initiation or an increase in existing dose of oral antihistamines or topical 
antipruritics: 
o Intolerable pruritus as the sole symptom of worsening cholestasis (i.e., without 
jaundice) 
• For initiation or an increase in existing dose of UDCA: 
o Onset of symptoms consistent with clinically significant worsening cholestasis, 
such as new onset of jaundice 
If worsening pruritus is the sole symptom of worsening cholestasis, a trial of oral 
antihistamines or topical antipruritics (initiation of, or an increase in existing 
dose) should be attempted before initiating UDCA. 
o Laboratory criteria:  Sustained increase of sBA >100 μmol/L  
The rationale for initiation of rescue medication, start/stop dates, and times of rescue medication 
administration as well as the name and dosage regimen of the rescue medication must all be 
recorded in the electronic case report form (eCRF). 
6.8.2. 
Prohibited Medications 
None of the following medications are allowed during the conduct of the study: 
• Any investigational drug, or medical device 
• IBATi other than volixibat 
• UDCA (except as permitted in Part 1 and/or in Section 6.8.1.2) or other therapeutic 
bile acids 
• Methotrexate 
• Statins 
• Bile acid/lipid-binding resins or sodium phenylbutyrate 
• Rifampin 
• PPAR agonists/fibrate drugs 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
66 
• S-adenosylmethionine 
• Any medications for the treatment of cholestasis – on- or off-label use 
• Known hepatotoxins (e.g., cyclosporine, tacrolimus, JAK inhibitors [when dosed 
systemically], pancreatic lipase inhibitors [when dosed systemically], drugs 
[including any medicinal products, herbs, etc.] that are known to cause DILI at the 
therapeutic labeled doses) 
• Progesterone supplementation 
• Cholestasis-inducing medications, unless required short-term for safety reasons and 
with medical monitor approval (e.g., short-term use of antibiotics for group B 
streptococcus prevention if no viable alternatives are available) 
• Initiation or change in dosing of prior antipruritic therapies (except as permitted in 
Section 6.8.1.2) 
6.8.3. 
Treatment after End of Study 
There is no study-specified treatment after the end of study. 
7. 
DISCONTINUATION OF STUDY DRUG AND PARTICIPANT 
WITHDRAWAL CRITERIA 
7.1. 
Discontinuation of Study Drug 
Participants may elect to discontinue study drug at any time for any reason. 
Whenever possible, participants who discontinue study drug should continue in the study on a 
weekly visit schedule until completion of F2, 28 (±3) days after delivery as outlined in the SoA 
(Table 1). 
A participant will be discontinued from study drug for any of the following reasons: 
• Withdrawal of consent by the participant  
• Emergency unblinding of treatment assignment by the investigative site 
• Criteria for stopping drug due to suspected DILI are met (refer to Appendix 3) 
• Any AE or progression of ICP refractory to rescue medication use that leads the 
investigator to decide that the participant should be withdrawn from study drug, 
including but not limited to the following: 
Any AE of Common Terminology Criteria for Adverse Events (CTCAE) Grade 4, 
related to study drug 
• Evidence of hepatic decompensation, including variceal bleeding, hepatic 
encephalopathy and/or ascites 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
67 
• In the opinion of the investigator or study medical monitor, it is medically 
unacceptable or otherwise not in the participant’s best interest to continue with study 
drug 
• Gross noncompliance, including failure to adhere to the study requirements as stated 
in the study protocol. 
Refer to the SoA (Table 1) for data to be collected at the time of end of treatment and follow-up 
and for any further evaluations that need to be completed. 
7.2. 
Participant Withdrawal from Study 
A participant may withdraw from the study at any time for any reason without prejudice to future 
medical care by the physician or at the institution.  The sponsor or designee may discontinue the 
participant from the study at any time.  If an investigator determines that a participant’s 
discontinuation from study is warranted, such action should be discussed with the sponsor or 
designee, when possible, in advance of the discontinuation.  The reason for termination and the 
date of stopping study drug must be recorded in source documents. 
Participants who discontinue from the study for safety reasons are followed as long as clinically 
indicated or until a safety finding is considered to be permanent. 
Participants who discontinue from the study will not be replaced. 
If a participant withdraws consent for disclosure of future information, the sponsor may retain 
and continue to use any data collected before such a withdrawal of consent. 
A participant who withdraws from the study may request destruction of any samples taken and 
not tested, and the investigator must document this in the site study records. 
The reason for termination and the date of stopping study drug must be recorded in source 
documents.  The evaluations listed for the early termination visit are to be performed as 
completely as possible for any participant who discontinues from study participation.   
Data to be collected at the time of study discontinuation and follow-up and for any further 
evaluations that need to be completed are outlined in the SoA (Table 1). 
7.3. 
Lost to Follow-Up 
A participant will be considered lost to follow-up if she fails to return for 3 or more scheduled 
visits and is unable to be contacted by the study site. 
The following actions must be taken if a participant fails to return to the clinic for a required 
study visit: 
• The site must attempt to contact the participant and reschedule the missed visit as 
soon as possible and counsel the participant on the importance of maintaining the 
assigned visit schedule and ascertain whether the participant wishes to and/or should 
continue in the study. 
• Before a participant is deemed lost to follow-up, the investigator or designee should 
make every effort to regain contact with the participant (where possible, 3 telephone 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
68 
calls and, if necessary, a certified letter to the participant’s last known mailing 
address or local equivalent methods).  These contact attempts should be documented 
in the participant’s medical record. 
• If the participant continues to be unreachable, the participant will be considered to 
have withdrawn from the study with a primary reason of lost to follow-up. 
8. 
STUDY ASSESSMENTS AND PROCEDURES 
Protocol waivers or exemptions are not allowed. 
Immediate safety concerns should be discussed with the medical monitor immediately upon 
occurrence or awareness to determine whether the participant should continue or discontinue 
study drug. 
Adherence to the study design requirements, including those specified in the SoA (Table 1), is 
essential and required for study conduct. 
All screening evaluations must be completed and reviewed to confirm that potential participants 
meet all eligibility criteria.   
Procedures conducted as part of the participant’s routine clinical management (e.g., sBA) and 
obtained before signing of the informed consent form (ICF) may be used for screening purposes, 
provided the procedures meet the protocol-specified criteria and are performed within the time 
frame defined in the SoA (Table 1). 
8.1. 
Administration and General Procedures 
8.1.1. 
Informed Consent 
The investigator or medically qualified designee (consistent with local requirements) will obtain 
informed consent, as described in Section 11.3, from each potential participant before she 
participates in this study. 
8.1.2. 
Assignment of Participant Identification Number 
All consented participants will be assigned a unique number that will be used to identify the 
participant for all screening procedures and will serve as the Participant ID number following 
randomization.  Each participant will be assigned only 1 participant number for each screening.  
Participant numbers must not be re-used for different participants.   
8.1.3. 
Inclusion/Exclusion Criteria 
At the screening and baseline visits, all inclusion (Section 5.1) and exclusion criteria 
(Section 5.2) will be reviewed by the investigator to ensure that the participant qualifies for the 
study. 
8.1.4. 
Demography 
Participant demographic information including sex, age (date of birth), and race, as allowed per 
local regulations, will be collected during the screening visit. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
CONFIDENTIAL 
69 
8.1.5. 
Prior and Concomitant Treatments 
Specific prior treatments and therapies administered for treatment of pruritus or ICP will be 
collected.  All concomitant treatment and therapies for any indication will also be collected per 
the SoA (Table 1).  All prior and concomitant treatment information must be recorded in the 
participant’s source documents. 
8.1.6. 
Medical, Menstrual, and Obstetric History 
A medical history will be obtained by the investigator or qualified designee.  All clinically or 
medically relevant information must be recorded, regardless of how much time has elapsed since 
the date of diagnosis.  Menstrual history (e.g., last menstrual period [LMP] and date of positive 
human chorionic gonadotropin test), and obstetric history (e.g., previous pregnancies including 
terminations of pregnancy and/or spontaneous abortions, genetic screenings, aneuploidy 
screening, teratogen exposures since LMP/pregnancy, infections [i.e., Covid-19, Zika, HIV, or 
hepatitis], travel outside the country, history of in vitro fertilization or other fertility treatments, 
history of cerclage placement) will be obtained. 
8.1.7. 
Estimated Gestational Age Assessment 
Confirmation of estimated gestational age is required during the screening period (i.e., before 
randomization).  Records of gestational age confirmation by 1st or 2nd trimester ultrasound should 
be reviewed; ultrasound should be performed during the screening period if not previously done 
or if prior records are unavailable.  Acceptable criteria include CRL from early ultrasound or 
head circumference on ultrasound if CRL is >84 mm, supporting a gestational age between 
20 weeks 0 days and the following: 
•
No more than 37 weeks 0 days or 35 weeks 0 days for singleton or twin gestation,
respectively, inclusive, at the baseline visit (Day 0) for Part 1
•
No more than 36 weeks 0 days, inclusive, at the baseline visit (Day 0) for Part 2
8.1.8. 
Screening Visit 
The screening visit(s) will occur up to 10 days prior to randomization.  The investigators may 
randomize participants as soon as participant’s eligibility is confirmed.  All screening procedures 
are expected to be completed within the 10-day screening period.  See SoA (Table 1) for details. 
8.1.9. 
Baseline Visit 
The baseline visit should occur in the morning, whenever possible.  After eligibility for 
randomization is confirmed, the following assessments must be performed in order; please refer 
to the SoA (Table 1) for details. 
1. PRO assessments
2. Nonfasting (e.g., postprandial) blood draw for sBA and other laboratories, per the SoA
3. First dose of study drug under direct observation, with fetal monitoring pre- and 
post-dose (see Section 8.4.2 for details).  The first dose of study drug must be 
administered only after the sBA blood draws have been completed.


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
70 
Note:  Participants may have the option to complete the baseline visit PRO assessments (i.e., 
5D-itch scale, CSS, EQ-5D-5L, PROMIS SF v1.0-Fatigue 7a, PROMIS SF v1.0-Sleep 
Disturbance, PIS-Itch) at home before they arrive onsite for the baseline (Day 0) visit. 
Timing of other required procedures at the baseline visit is at the investigator’s discretion. 
8.1.10. 
Randomization 
Participants who are eligible for Part 1 will be randomized (1:1) via IRT to receive either 
volixibat 20 mg BID or volixibat 80 mg BID. 
Participants who are eligible for Part 2 will be randomized (1:1) via IRT to receive the volixibat 
dose BID selected at the interim analysis following Part 1 or matching placebo. 
8.1.11. 
Study Drug Administration 
Participants are to take their study drug as prescribed.  As much as possible, each dose should be 
administered ~30 minutes before meals to better cover the luminal bile acid release associated 
with meals.  
The first dose of study drug will be administered under observation in the clinic; monitoring of 
fetal well-being will be performed before and after dosing via NST/CTG or BPP or 
auscultation/visualization of fetal cardiac activity if NST/CTG and/or BPP are not feasible due to 
gestational age (see Section 8.4.3 for additional details). 
8.1.12. 
Management of Timing for Possible Elective Delivery 
Recommendations for timing of delivery in ICP pregnancies are inconsistent in guidelines across 
the world (see Section 2.2).  For the purposes of consistency within this study and unless 
contraindicated for safety reasons for an individual participant, whenever possible investigators 
are advised to follow the RCOG guidelines for the management of ICP in effect at the time of a 
participant’s randomization when making decisions regarding timing of delivery.  
Recommendations from RCOG’s COVID-19 guidance for maternal medicine services (2020) 
include: 
• If bile acids are below 100 µmol/L at diagnosis, repeat bile acid testing should be offered 
at any in-person appointments held from 34 weeks of gestation, or at 37 weeks of 
gestation as a minimum, in order to guide delivery timing.  If bile acids remain below 
100 µmol/L, a planned birth at 39 weeks should be considered. 
• If bile acids are 100 µmol/L or above, a repeat blood test for sBAs at 34 weeks of 
gestation should be offered.  If they remain raised, the benefits and risks of planned birth 
at 35–36 weeks of gestation should be discussed with the woman. 
8.1.13. 
Delivery Visit 
Delivery may occur at a hospital other than clinical site in the event of an emergency.  For the 
Delivery Visit, the investigator/clinical coordinator can visit the delivery hospital or the 
participant can visit the investigative site after delivery.  Whenever possible, every effort should 
be made to collect all assessments specified in the SoA (Table 1) for this visit, especially the 
PRO/quality-of-life assessments, within 24 hours after delivery. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
71 
8.2. 
Efficacy Assessments 
8.2.1. 
Serum Bile Acids 
Samples for sBA determinations will be collected at times shown in the SoA (Table 1).  The 
samples will be frozen and shipped to the designated laboratory for analysis for total sBA, as 
needed.  Sample collection, processing, and shipping instructions will be provided to the site 
separately. 
8.2.2. 
Adult ItchRO  
The Adult ItchRO (Appendix 4) is an 11-point NRS measurement of worst itch severity ranging 
from 0=no itch to 10=worst possible itch, rated over the past 24 hours and completed daily in an 
eDiary within a prespecified time window.   
8.2.3. 
Composite Adverse Perinatal Outcomes 
The composite adverse perinatal outcomes will comprise the following: 
• Perinatal death, defined as in utero fetal death after randomization or known neonatal 
death up to 28 days after birth 
• Spontaneous preterm delivery, defined as delivery at <37 weeks’ gestational age 
following spontaneous onset of preterm labor or PPROM 
• Iatrogenic preterm delivery attributable to ICP or ICP-related complications, defined 
as delivery at <37 weeks’ gestational age resulting from medical intervention (i.e., 
augmentation/induction of labor or cesarean delivery without prior spontaneous onset 
of preterm labor or PPROM with one or more of the following as the indication for 
delivery): 
o Diagnosis of ICP with or without suspected fetal compromise 
o Persistently elevated/increasing sBA level 
o Worsening hepatic function 
o Intolerable maternal ICP symptoms 
• Neonatal unit admission for ≥12 hours from birth until hospital discharge for one or 
more of the following indications: 
o Respiratory insufficiency/failure with requirement for oxygen supplementation 
o Noninvasive or invasive respiratory support 
o Hemodynamic instability or shock requiring clinical intervention 
o Metabolic acidosis or signs of asphyxia 
o Proven infection 
o Hypoglycemia or feeding problems requiring IV fluids or tube feeding 
o Meconium-stained amniotic fluid and/or its sequelae (e.g., meconium aspiration, 
etc.) 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
72 
Data on outcomes described in the SoA (Table 1) under “Perinatal outcomes assessment” shall 
be collected in the eCRFs.  
8.2.4. 
5-D Itch Scale 
The 5-D Itch scale is a 5-item measure of 5 dimensions of itching (duration, degree [intensity], 
direction [degree of change], disability [impact], and distribution [location]).  See the SoA 
(Table 1) and Appendix 5 for time points and details.   
8.2.5. 
Clinician Scratch Scale 
The CSS is a clinician assessment of itch severity, and to the extent possible, should be made by 
the same investigator or designee during study visits.  The assessment focuses on visible damage 
to the skin as a result of scratching, as observed by the clinician.  Clinicians rate a participant’s 
skin damage due to itch using 5 rating options, ranging from None to Cutaneous mutilation, 
hemorrhage, and scarring evident.  The CSS will be used as a co-validator in the assessment of 
the convergent validity of the Adult ItchRO scores.  See the SoA (Table 1) and Appendix 6 for 
time points and details.   
8.2.6. 
EuroQoL 5-Dimension 5-Level 
The EQ-5D-5L is a widely used standardized measure of health status that provides a descriptive 
profile and single index value to appraise a respondents' health status (Herdman et al. 2011; 
Oppe et al. 2014).  The measure was designed for both clinical and economic appraisal and has 
been validated in numerous clinical populations (Cella et al. 2012).  It uses a recall period of 
“Today.”  The EQ-5D-5L comprises 5 dimensions:  Mobility, Self-care, Usual Activities, 
Pain/Discomfort, and Anxiety/Depression.  These dimensions are measured using a 5-point 
rating scale ranging from no problems to extreme problems (e.g., I am extremely anxious or 
depressed).  Developers of the measure deliberately describe the rating scale for the measure as 
noncardinal with no arithmetic properties.  Responses to the 5 dimensions are used to compute a 
single utility index score ranging from 0.0 to 1.0, which represents the general health status of 
the individual.  The EQ-5D-5L also contains a visual analog scale to assess the participant's 
overall health.  The EQ-5D-5L will be used in exploratory descriptive analyses.  The EQ-5D-5L 
will be used as a co-validator in the assessment of the convergent validity of the Adult ItchRO 
scores. 
8.2.7. 
PROMIS SF v1.0-Fatigue 7a 
The PROMIS SF v1.0-Fatigue 7a is the original 7-item short form of the PROMIS Fatigue 
measure.  See the SoA (Table 1) and Appendix 7 for time points and details.   
8.2.8. 
PROMIS SF v1.0-Sleep Disturbance 
The PROMIS SF v1.0-Sleep Disturbance in an 8-item measure that assesses quality of sleep, 
sleep depth, and restoration associated with sleep (Yu et al. 2012).  See the SoA (Table 1) and 
Appendix 7 for time points and details.   


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
73 
8.2.9. 
Patient Impression of Severity-Itch 
The PIS-Itch is a modified version of commonly used impression of change scale designed for 
self-administration.  See the SoA (Table 1) and Appendix 8 for time points and details.   
8.2.10. 
Patient Global Impression of Change-Itch 
The PGIC-Itch was designed to assess change in itching after being treated with study drug from 
the specified time point compared with baseline.  See the SoA (Table 1) and Appendix 9 for time 
points and details.   
8.2.11. 
Exploratory Markers of Bile Acid Synthesis, Inflammation, Pruritogens 
Serum 7αC4 and FGF-19 will be evaluated as markers of bile acid synthesis.  Samples will be 
collected at the times shown in the SoA (Table 1).  Sample collection, processing, and shipping 
instructions will be provided to the site separately. 
Additional biomarkers of inflammation (GLP-1) and pruritogens (autotaxin, progesterone 
sulfate) will also be evaluated and collected at times shown in the SoA. 
8.3. 
Adverse Event Collection 
At each study visit, participants will be questioned in a general way to ascertain whether AEs 
have occurred since the previous visit (e.g., “Have you had any health problems since your last 
visit?”).  Refer to Section 9 for additional information.   
The investigator and/or designees are responsible for detecting, documenting, and reporting 
events that meet the AE/SAE/AESI/ECI reporting criteria described in Sections 9.2.1 and 9.2.6.  
8.3.1. 
Time Period for Collection 
All SAEs will be collected from the signing of the ICF until whichever of the following time 
points comes last:  the F2 or up to 30 days after date of discharge from hospital for mother or for 
the baby, respectively, as specified in the SoA (Table 1). 
All AEs will be collected from first dose of study drug until whichever of the following time 
points comes last:  the F2, or up to 30 days after date of discharge from hospital for mother or for 
the baby, as specified in the SoA (Table 1). 
All SAEs/AESIs will be reported to the sponsor or designee within 24 hours of the site staff or 
personnel awareness. 
Adverse perinatal events that are included in the key secondary composite endpoint should not 
be captured as AEs or SAEs because they will already be captured as endpoints for the purposes 
of efficacy assessment.  Refer to Sections 3.2 and 3.3 for details.   
Medical occurrences that begin before the start of study drug but after obtaining informed 
consent will be recorded in the medical history/current medical conditions eCRF and not the AE 
eCRF unless they meet seriousness criteria. 
8.4. 
Safety Assessments 
Planned time points for all safety assessments are provided in the SoA (Table 1). 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
74 
8.4.1. 
Perinatal Assessment 
The following data and/or assessments will be collected on or after the delivery visit per the SoA 
(Table 1); the time period for collection of newborn data is as outlined in Section 8.3.1.  
• Gestational age at delivery 
• Mode of delivery (e.g., vaginal, operative vaginal, cesarean; and iatrogenic versus 
spontaneous) 
• Indication(s) for delivery, if iatrogenic 
• Maternal estimated blood loss at delivery 
• Apgar score at 5 minutes of life 
• Birth weight of infant 
• Placental weight 
• Umbilical cord assessments, when possible (see Section 8.4.8 for details on order of 
collections) 
• Maternal and fetal (umbilical cord, when possible) volixibat concentrations  
• Presence/absence of meconium-stained amniotic fluid 
• Neonatal admission diagnoses, treatment details, duration of stay including NICU 
data if applicable 
8.4.2. 
Fetal Ultrasound 
At screening or baseline and every 4 weeks while on study drug, a fetal ultrasound should be 
performed to exclude evidence of significant intrauterine fetal growth restriction or placental 
insufficiency.  This ultrasound should include umbilical artery dopplers if indicated for estimated 
fetal weight <10th percentile or for other obstetric indications.  Ultrasounds shall be performed 
and read locally.   
Results should be reviewed by the investigator or qualified delegate within 1 business day.  If the 
ultrasound demonstrates evidence suggesting new-onset intrauterine growth restriction (e.g., new 
finding of estimated fetal weight <10th percentile, or estimated fetal weight known to be <10th 
percentile before dosing with a decrease to <3rd percentile while on study drug) or evidence of 
new onset placental insufficiency (e.g., new onset of absent or reversed end diastolic flow), the 
participant should be managed according to local obstetric standard of care/best practices and the 
medical monitor should be notified. 
8.4.3. 
Antepartum Fetal Monitoring 
To ensure fetal well-being, antepartum fetal monitoring will be performed before and after the 
first dose of study drug; thereafter, fetal monitoring will be continued at the investigator’s 
discretion or for local standard-of-care obstetric indications.  The following are acceptable 
options for fetal monitoring: 
• NST/CTG 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
75 
• BPP 
• Fetal heart rate auscultation using Doppler device, ultrasound, or fetal stethoscope 
(i.e., fetoscope), only if early gestational age precludes a technically adequate 
NST/CTG or BPP (e.g., gestational age <24 weeks) 
Results of the monitoring assessment should be reviewed by the investigator or qualified 
delegate prior to the participant leaving the clinic.  Participants with non-reassuring fetal 
assessments should be managed according to local obstetric standard of care/best practices.  
8.4.4. 
Physical Examination 
A complete physical examination will be performed by the investigator or designee and will 
include an assessment of the following body systems:  general appearance; skin; head, eyes, ears, 
nose, and throat; spine, neck, thyroid; musculoskeletal; cardiovascular; respiratory; neurological; 
and abdomen (including liver and kidneys).  Height (at screening only) and weight (on days as 
specified on the SoA [Table 1]) will also be measured and recorded.  A brief physical 
examination will be a symptom-directed examination focused on changes from the last 
examination.  Investigators should pay special attention to clinical signs related to previous 
serious illnesses. 
Abnormalities identified during screening will be documented in the participant’s source 
documents, on the medical history eCRF, and/or the AE eCRF (if the AE meets seriousness 
criteria).  New findings or changes after the first dose of study drug will be captured as AEs on 
the AE eCRF page, as deemed by the investigator. 
Height and weight at the screening visit and weight upon discharge will be recorded.  Height 
should be measured in centimeters and weight should be measured in kilograms.  Measurements 
should be taken in light clothing and stocking feet (without shoes) with empty pockets.  The 
participant’s height should be recorded to the nearest centimeter and weight should be recorded 
to the nearest 0.1 kg.  Height and weight will be used to calculate body mass index (BMI) 
through use of the following formula:  
BMI=weight (kg)/(height [m])2 
8.4.5. 
Vital Signs 
Vital signs will be taken in the semi-recumbent position after at least 5 minutes of rest and will 
include systolic and diastolic blood pressure and pulse at all time points.  Vital signs may be 
repeated at the screening visit as needed. 
8.4.6. 
Fetal Heart Rate Confirmation 
Confirmation of fetal cardiac activity via auscultation with a Doppler device, ultrasound, or fetal 
stethoscope (i.e., fetoscope) should be performed at each visit while the participant is pregnant.  
Participants with non-reassuring fetal assessments should be managed according to local 
obstetric standard of care/best practices. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
76 
8.4.7. 
Clinical Laboratory Evaluations 
Refer to Appendix 1 for the list of clinical laboratory tests to be performed and to the SoA 
(Table 1) for the timing and frequency.  The investigator must review the laboratory report, 
document this review, and record any clinically relevant changes occurring during the study in 
the AE section of the eCRF.  The laboratory reports must be filed with the source documents.  
Clinically significant abnormal laboratory findings are those that are not associated with an 
underlying disease.  
All laboratory tests with values considered clinically significantly abnormal during participation 
in the study or within 7 (±2) days after the last dose of study drug should be repeated until the 
values return to normal or baseline or are no longer considered clinically significant by the 
investigator or medical monitor. 
If such values do not return to normal/baseline within a period of time judged reasonable by the 
investigator, the etiology should be identified and the sponsor notified. 
All protocol-required laboratory assessments, as defined in Appendix 1, must be conducted in 
accordance with the SoA (Table 1). 
If laboratory values from non-protocol–specified laboratory assessments performed at a local 
laboratory require a change in participant management or are considered clinically significant by 
the investigator (e.g., SAE or AE), then the results must be recorded in the eCRF.  The 
investigators will maintain a copy of the reference ranges (with the record of the reference 
ranges) for the local laboratory(ies) used.  
All clinical laboratory assays will be performed according to the laboratory’s normal procedures.  
Reference ranges are to be supplied by the laboratory and will be used to assess the clinical 
laboratory data for clinical significance and out-of-range pathological changes.  The investigator 
should assess out-of-range clinical laboratory values for clinical significance, indicating if the 
value(s) is/are not clinically significant or clinically significant.  Abnormal clinical laboratory 
values that are unexpected or not explained by the participant’s clinical condition may, at the 
discretion of the investigator or sponsor, be repeated as soon as possible until confirmed, 
explained, or resolved.  
Sample reserves may be obtained by aliquoting samples already drawn for scheduled 
assessments per the SoA (Table 1); please refer to the study laboratory manual for additional 
details and instructions.  These samples can be stored up to 5 years following the completion of 
the study and used for additional safety assessments, measure drug levels, potential new 
biochemical markers, and/or to replace any missing or discarded samples.  
8.4.8. 
Umbilical Cord Assessment 
An umbilical cord sample will be obtained at delivery, when possible, for the (potential) 
assessments of: 
• Umbilical artery pH 
• Volixibat plasma levels 
• sBA 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
77 
• Total cholesterol 
• LDL 
• Glucose 
If obtained, umbilical artery pH sampling should be performed first, followed by sampling for 
volixibat plasma levels.  Thereafter, samples for sBA, total cholesterol, LDL cholesterol, and 
glucose may be obtained in any order. 
8.4.9. 
Drug and Alcohol Screen 
A urine screen for alcohol and drugs of abuse will be performed at screening as described in the 
SoA (Table 1).  Additional drug and alcohol screens may be performed at the investigator’s 
discretion. 
Urine samples are to be tested for ethanol, amphetamines, barbiturates, benzodiazepines, 
cannabinoids, cocaine, methadone, opiate metabolite, and phencyclidine.   
Results of urine drug and alcohol screens will be reviewed and verified by the study monitor 
(CRA) but will not be collected in the eCRF database.  Any positive result for drugs of abuse or 
alcohol at the screening visit will exclude the participant from further participation in the study. 
8.4.10. 
Serology Screen 
At the screening visit, a blood sample will be drawn to test for the presence of HIV, HBsAg, and 
HCV antibodies.  The test results must be confirmed as negative before enrollment in the study.  
If a test result is positive, the participant will be excluded from entering the study.  Results of the 
virology screen will be reviewed and verified by the study monitor (CRA) but will not be 
collected in the eCRF. 
8.4.11. 
Coagulation Panel 
The coagulation panel is listed in Appendix 1.  A blood sample will be drawn at the time points 
described in the SoA (Table 1). 
8.4.12. 
Lipid Panel  
A blood sample will be drawn for a full lipid panel at the time points described in the SoA 
(Table 1). 
8.4.13. 
Glycated Albumin Evaluation 
A blood sample will be drawn for glycated albumin, a biomarker of glucose metabolism, at the 
time points described in the SoA (Table 1). 
8.4.14. 
Fat-Soluble Vitamin Evaluation 
Fat-soluble vitamin levels (vitamins A, D, and E) will be assessed at the time points indicated in 
the SoA (Table 1).  It is important to protect the sample collection tube from light when drawing 
samples for these analytes. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
78 
8.4.15. 
Electrocardiograms 
At or after the screening visit, local ECGs may be performed, if clinically indicated for 
evaluation of symptoms.   
8.5. 
Pharmacokinetics 
Plasma samples will be collected for measurement of maternal plasma and umbilical cord plasma 
(when possible) concentrations of volixibat as specified in the SoA (Table 1). 
The actual date and time (24-hour clock time) of each sample will be recorded.  Sample 
collection, processing, and shipping instructions will be provided to the site separately in the 
study laboratory manual. 
Each plasma sample will be divided into 2 aliquots (1 each for initial analysis and a back-up).  
Samples collected for analyses of volixibat plasma concentration may also be used to evaluate 
safety or efficacy aspects related to concerns arising during or after the study. 
Genetic analyses will not be performed on these plasma samples unless consent for this was 
included in the informed consent.  Participant confidentiality will be maintained. 
8.6. 
Pharmacodynamics 
Blood samples will be collected for measurement of sBA at time points specified in the SoA 
(Table 1).  The actual collection times will be reported in the eCRF.  The samples will be frozen 
and shipped to the designated laboratory for analysis of total sBA, as needed.  Sample collection, 
processing, and shipping instructions will be provided to the site separately in the study 
laboratory manual. 
8.7. 
Biomarkers 
Collection of samples for other biomarker research is also part of this study; please see the study 
laboratory manual, SoA (Table 1), and Section 8.2.11 for details. 
8.8. 
Genetics 
Sample(s) (maternal and/or umbilical cord) for DNA isolation may be collected from participants 
who have consented to participate in the genetic analysis component of the study.  Participation 
is optional.  Participants who do not wish to participate in the genetic research may still 
participate in the study. 
In the event of DNA extraction failure, a replacement genetic blood sample may be requested 
from the participant.  Signed informed consent will be required to obtain a replacement sample 
unless it was included in the original consent. 
See Appendix 2 for information regarding genetic research.  Details on processes for collection 
and shipment and destruction of these samples will be specified in the study laboratory manual 
prior to study initiation. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
79 
8.9. 
Healthcare Utilization 
Healthcare utilization data associated with medical encounters for the mother and for the neonate 
will be collected in the eCRF for all participants, as specified in the SoA (Table 1).  
Protocol-mandated procedures, tests, and encounters are excluded. 
The data collected may be used to conduct exploratory economic analyses and will include the 
following: 
• Number and duration of medical care encounters, including surgeries, and other 
selected procedures (inpatient and outpatient) 
• Dates and duration of hospitalization (total days or length of stay, including duration 
by wards [e.g., intensive care unit]) 
• Number and type of diagnostic and therapeutic tests and procedures 
• Outpatient medical encounters and treatments (including physician or emergency 
department visits, tests and procedures, and medications) 
9. 
SAFETY REPORTING 
9.1. 
Safety Parameters and Definitions 
9.1.1. 
Adverse Events 
An AE is any untoward medical occurrence in a patient or clinical study participant or the 
newborn, temporally associated with the use of study drug, whether or not considered related to 
the study drug.  NOTE:  An AE can therefore be any unfavorable and unintended sign (including 
an abnormal laboratory finding or vital sign), symptom, or disease (new or exacerbated) 
temporally associated with the use of study drug.  For the AE collection period, see the SoA 
(Table 1) and Section 8.3.1.  
This includes the following: 
• Any abnormal laboratory test results (hematology, clinical chemistry, or urinalysis) or 
other safety assessments (e.g., radiological scans, vital signs measurements), 
including those that worsen from baseline, considered clinically significant in the 
medical and scientific judgment of the investigator (i.e., not related to progression of 
underlying disease). 
• Exacerbation of a chronic or intermittent preexisting condition including either an 
increase in frequency and/or intensity of the condition  
• New conditions detected or diagnosed after study drug administration even though it 
may have been present before the start of the study 
The following events are NOT considered an AE: 
• Any clinically significant abnormal laboratory findings, vital signs or other abnormal 
safety assessments that are associated with the underlying disease, unless judged by 
the investigator to be more severe than expected for the participant’s condition 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
80 
• An investigational abnormality (e.g., laboratory parameter, vital sign, or ECG) unless 
the abnormality is considered clinically significant by the investigator based on at 
least 1 of the following criteria: 
o Induces clinical signs or symptoms 
o Requires active intervention (including referring a participant to a specialist) 
o Requires interruption or discontinuation of study drug 
• The disease/disorder being studied or expected progression, signs, or symptoms of the 
disease/disorder being studied, unless more severe than expected for the participant’s 
condition.  Adverse perinatal events that are included in the key secondary composite 
endpoint should not be captured as AEs or SAEs because they will already be 
captured as endpoints for the purposes of efficacy assessment. 
• Medical or surgical procedure (e.g., endoscopy, appendectomy):  the condition that 
leads to the procedure is the AE 
• Elective procedures and preplanned interventions for preexisting conditions that did 
not worsen since the start of the study 
• Situations in which an untoward medical occurrence did not occur (social and/or 
convenience admission to a hospital) 
• Anticipated day-to-day fluctuations of preexisting disease(s) or condition(s) present 
or detected at the start of the study that do not worsen 
9.1.2. 
Serious Adverse Events 
If an event is not an AE per definition above, then it cannot be an SAE, even if serious 
conditions are met (e.g., hospitalization for signs/symptoms of the disease under study, death due 
to progression of disease).  An SAE is defined as any untoward medical occurrence that, at any 
dose: 
• Results in death 
• Is life-threatening (the term “life-threatening” in the definition of “serious” refers to 
an event in which the participant was at risk of death at the time of the event.  It does 
not refer to an event, which hypothetically might have caused death if it were more 
severe.) 
• Requires inpatient hospitalization or prolongation of existing hospitalization 
Hospitalization signifies that the participant has been detained (usually involving at 
least a 24-hour stay) at the hospital or emergency ward for observation and/or 
treatment that would not have been appropriate in the physician’s office or outpatient 
setting.  Complications that occur during hospitalization are AEs.  If a complication 
prolongs hospitalization or fulfills any other serious criteria, the event is serious.  
When in doubt as to whether “hospitalization” occurred or was necessary, the AE 
should be considered serious. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
81 
Hospitalization for elective treatment of a preexisting condition that did not worsen 
from baseline is not considered an AE.  
Hospitalization for delivery is not considered an SAE unless there was prolongation 
of the hospitalization beyond the normally expected duration for vaginal or cesarean 
birth; in such situations, the diagnosis responsible for the prolongation of 
hospitalization should be considered the SAE. 
• Results in persistent disability/incapacity 
A substantial disruption of a person’s ability to conduct normal life functions 
This definition is not intended to include experiences of relatively minor medical 
significance, such as uncomplicated headache, nausea, vomiting, diarrhea, influenza, 
and accidental trauma (e.g., sprained ankle) that may interfere with or prevent 
everyday life functions but do not constitute a substantial disruption. 
• Is a congenital anomaly/birth defect 
• Other situations (Important Medical Events) 
Medical or scientific judgment should be exercised in deciding whether SAE 
reporting is appropriate in other situations, such as important medical events that may 
not be immediately life-threatening or result in death or hospitalization but may 
jeopardize the participant or may require medical or surgical intervention to prevent 
one of the other outcomes listed in the above definition.  These events should usually 
be considered serious. 
Examples of such events include invasive or malignant cancers, intensive treatment in 
an emergency department or at home for allergic bronchospasm, blood dyscrasias, or 
convulsions that do not result in hospitalization, or development of drug dependency 
or drug abuse.   
9.2. 
Reporting and Follow-Up of AEs and/or SAEs 
9.2.1. 
AE and SAE Reporting 
• When an AE/SAE occurs, it is the responsibility of the investigator to review all 
documentation (e.g., hospital progress notes, laboratory reports, and diagnostics 
reports) related to the event. 
• The investigator should report all relevant AESI/SAE information within 24 hours of 
site personnel awareness of the event following the instructions provided by the 
sponsor.  
• It is not acceptable for the investigator to send photocopies of the participant’s 
medical records in lieu of completion of the AE/SAE eCRF page. 
• There may be instances when copies of medical records for certain cases are 
requested by the sponsor or designee.  In this case, all participant identifiers, with the 
exception of the participant number, will be redacted on the copies of the medical 
records before submission to the sponsor or designee.   


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
82 
• 
The investigator will attempt to establish a diagnosis of the event based on signs, 
symptoms, and/or other clinical information.  Whenever possible, the diagnosis (not 
the individual signs/symptoms) will be documented as the AE/SAE. 
9.2.2. 
Assessment of Intensity/Severity 
The investigator will make an assessment of the maximum intensity/severity for each AE and 
SAE according to the National Cancer Institute CTCAE, version 5.0.  
An event is defined as “serious” when it meets at least one of the predefined outcomes as 
described in the definition of an SAE, not when it is rated as severe. 
Should a participant experience any AE not listed in the CTCAE, the following grading 
system should be used to assess severity: 
• Grade 1:  Mild; asymptomatic or mild symptoms OR clinical or diagnostic 
observations only OR intervention not indicated. 
• Grade 2:  Moderate OR minimal, local, or noninvasive intervention indicated OR 
limiting age-appropriate instrumental activities of daily living. 
• Grade 3:  Severe or medically significant but not immediately life-threatening OR 
hospitalization or prolongation of hospitalization indicated OR disabling OR limiting 
self-care activities of daily living. 
• Grade 4:  Life-threatening consequences OR urgent intervention indicated. 
• Grade 5:  Death 
9.2.3. 
Assessment of Causality 
• The investigator is obligated to assess the relationship (related or not related) between 
study drug and each occurrence of each AE/SAE. 
• A “reasonable possibility” of a relationship conveys that there are facts, evidence, 
and/or arguments to suggest a causal relationship rather than that a relationship 
cannot be ruled out. 
• The investigator will use clinical judgment to determine the relationship. 
• Alternative causes, such as underlying disease(s), concomitant therapy, and other risk 
factors, as well as the temporal relationship of the event to study drug administration 
will be considered and investigated. 
• The investigator will also consult the IB for the assessment. 
• For each AE/SAE, the investigator must document in the medical notes that he or she 
has reviewed the AE/SAE and has provided an assessment of causality. 
• There may be situations in which an SAE has occurred, and the investigator has 
minimal information to include in the initial report to the sponsor or designee.  
However, it is very important that the investigator always make an assessment of 
causality for every event before the initial transmission of the SAE data to the sponsor 
or designee.  


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
83 
• The investigator may change his or her opinion of causality in light of follow-up 
information and send an SAE follow-up report with the updated causality assessment. 
• 
The investigator and sponsor causality assessments are used to determine whether an 
event meets the expedited safety reporting requirements. 
9.2.4. 
Reference Safety Information 
The Reference Safety Information within the Volixibat IB will be used for expectedness 
assessment for expedited safety reporting of SAEs.  
9.2.5. 
Expedited Safety Reporting 
The sponsor will comply with country-specific regulatory requirements relating to expedited 
safety reporting to regulatory authorities, institutional review boards (IRBs)/independent ethics 
committees (IECs), and investigators.  
An investigator who receives safety information (e.g., expedited safety report, periodic safety 
summaries, etc.) from the sponsor may need to notify the local IRB/IEC, according to local 
requirements.  
9.2.6. 
Adverse Events of Special Interest 
For this study, AESIs will include symptomatic cholelithiasis and threatened preterm labor; such 
events must be reported to the sponsor within 24 hours of site personnel awareness of the event, 
regardless of regulatory seriousness criteria or causality.  Specific reporting instructions will be 
included in the eCRF completion guidelines. 
9.2.7. 
Events of Clinical Interest  
ECIs will include CTCAE Grade ≥3 diarrhea, CTCAE Grade ≥3 abdominal pain, CTCAE 
Grade ≥3 transaminase increases, and fat-soluble vitamin deficiency; these will be subject to 
specialized, targeted data collections.  Please refer to Appendix 3 for algorithms to assess 
transaminase increases and/or potential DILI events. 
Additional ECIs may be identified during the course of the study.   
Specifics regarding events to be designated as ECIs, along with reporting instructions/timelines, 
will be included in the eCRF completion guidelines.  ECIs that meet seriousness criteria shall be 
subject to expedited reporting as outlined in Sections 9.2.1 and 9.2.5.  
9.2.8. 
Overdose and Special Reporting Situations 
Overdose is defined as intentional or unintentional intake of a dose of investigational product 
higher than the protocol-prescribed dose.  Treatment of overdose with volixibat would be 
consistent of general supportive measures, if applicable, including hydration and monitoring for 
fat-soluble vitamin deficiencies.  In the event of an overdose, the investigator should contact the 
medical monitor within 24 hours of site personnel awareness of the event.  The investigator must 
closely monitor the participant for any AE/SAEs and laboratory abnormalities for at least 
24 hours.  


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
84 
Decisions regarding dose interruptions or modifications will be made by the investigator in 
consultation with the medical monitor based on the clinical evaluation of the participant.  The 
sponsor does not recommend specific treatment for an overdose. 
Abuse, misuse, overdose, or medication errors are not considered AEs on their own; however, 
they must be reported to the sponsor whether or not they result in an AE/SAE as described in 
Section 9.2.1.  All AEs associated with abuse, misuse, overdose, or medication errors should be 
reported as per the standard process for reporting any AE.  The 24-hour reporting requirement 
for SAEs does not apply to reports of abuse, misuse, overdose, or medication errors unless these 
result in an SAE.  
The categories below are not mutually exclusive; the event can meet >1 category.  
• Abuse:  Persistent or sporadic intentional intake of investigational product when used 
for a nonmedical purpose (e.g., to alter one’s state of consciousness or get high) in a 
manner that may be detrimental to the individual and/or society  
• Misuse:  Intentional use of investigational product other than as directed or indicated 
at any dose (Note:  This includes a situation where the investigational product is not 
used as directed at the dose prescribed by the protocol)  
• Overdose:  Intentional or unintentional intake of a dose of investigational product 
higher than the protocol-prescribed dose  
• Medication Error:  An error made in prescribing, dispensing, administration, and/or 
use of an investigational product.  For studies, medication errors are reportable to the 
sponsor only as defined below.  
o Cases of participants missing doses of the investigational product are not 
considered reportable as medication errors.  
o Medication errors should be collected/reported for all products under 
investigation.  The administration and/or use of the unassigned treatment is/are 
always reportable as a medication error.  
o The administration and/or use of an expired investigational product should be 
considered as a reportable medication error.  
9.2.8.1. 
Disease Progression  
Disease progression itself (i.e., worsening of ICP) is not considered an AE unless it is considered 
atypical in presentation and/or considered to be related to the study drug.  Signs or symptoms of 
disease progression do not need to be reported as AEs/SAEs unless there is uncertainty as to their 
cause, in which case they may be reported as AEs. 
9.2.8.2. 
Liver Safety Monitoring 
Please refer to Appendix 3 for algorithms to assess liver safety and potential DILI events.  


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
85 
9.2.9. 
Lactation/Exposure during Breastfeeding 
Mothers who are breastfeeding at screening or planning to breastfeed at any time starting with 
the screening visit through completion of study drug with volixibat are excluded from study 
participation.   
The potential for volixibat to be excreted in human milk has not been studied at this time.  
However, given that volixibat is minimally absorbed and only sporadically detectable in plasma 
(most concentrations below the LLOQ), after single doses up to 300 mg and multiple doses up to 
80 mg BID with no observed accumulation, identification of detectable volixibat concentrations 
in human milk would be unlikely at the doses intended for study.   
The protocol-specified treatment period for volixibat ends with delivery.  There are no 
contraindications to initiation of breastfeeding the neonate immediately upon delivery. 
9.2.10. 
Follow-Up 
After the initial AE/SAE/AESI/ECI report, the investigator is required to proactively follow each 
participant at subsequent visits/contacts.  All events will be followed until the event resolves, 
returns to baseline, stabilizes, is otherwise explained, no further improvement is anticipated 
based on the medical judgement of the treating physician, or the participant is lost to follow-up. 
Investigators are not obligated to actively seek AEs or SAEs after study participants exit the 
study.  However, if the investigator learns of any SAEs that occurred in a participant after study 
exit and he or she considers the event to be reasonably related to the study drug, the investigator 
must notify the sponsor within 24 hours after awareness. 
10. 
STATISTICAL CONSIDERATIONS 
All predefined statistical analyses for the final analysis will be performed after the database is 
locked.  All statistical analyses will be performed using SAS software (SAS Institute, Cary, NC, 
USA) version 9.4 or higher. 
The statistical analysis plan (SAP) will provide the comprehensive statistical methods and 
definitions for the analysis of the efficacy and safety data, as well as describe the approaches to 
be taken for summarizing other study information, such as participant disposition, demographic 
and baseline characteristics, medical and disease history, study medication exposure, and prior 
medications.  All study data will be presented in participant listings. 
The study has 2 separate, self-standing parts, and each will have its own separate analyses.  Of 
note, a pooled safety analysis combining Parts 1 and 2 may be considered, whereas Part 1will not 
be combined in any of the efficacy analyses.  Additionally, efficacy analyses within Part 1 will 
be summarized separately based on UDCA usage at baseline. 
All inferential statistical tests will be 2-sided.  Summary statistics for continuous variables will 
include mean, median, standard deviation, SEM, minimum, maximum, and quartiles.  Summary 
of categorical variables will include sample size, number of occurrences, and percentages 
(95% CIs will be provided where appropriate). 
The SAP will be finalized prior to unblinding to preserve the integrity of the statistical analysis 
and study conclusions. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
86 
10.1. 
Sample Size Determination 
Part 1 of the study is designed for estimation without formal statistical testing; hence, there are 
no formal power considerations.  For example, with 20 participants per group and assuming a 
standard deviation of 25 for each group, a 95% CI for the mean for each volixibat arm would 
have a half width of 11.   
For the power calculations for Part 2, it is assumed that only a single dose will be selected at the 
end of Part 1, and a 2-sided alpha 0.05 will be used to test whether there is a difference between 
the 2 groups.  Thus, for Part 2, a sample size of 100 participants per arm has 80% power to detect 
mean difference of 10 with standard deviation of 25.  Power was calculated using SAS, 
version 9.4.  
10.2. 
Population for Analyses 
For purposes of analysis, the populations are defined in Table 3. 
Table 3 
Analyses Populations 
Population 
Description 
Enrolled 
All participants who sign the ICF 
ITT 
All randomized participants 
mITT 
All randomized participants who receive at least 1 dose of study drug 
(partial or complete).  Participants will be analyzed according to the 
treatment to which they were randomized.  
PP 
All participants in the mITT population who do not experience any major 
protocol violations 
Safety 
All participants who receive at least 1 dose of study drug.  Participants 
will be classified based upon the treatment they actually receive. 
ICF=informed consent form; ITT=intent-to-treat; mITT=modified intent-to-treat; 
PP=per-protocol. 
 
10.3. 
Participant Disposition, Demographics, and Baseline Characteristics 
Participant disposition, demographic and baseline characteristics, disease history, prior 
medications, treatment exposure, and compliance will be summarized by treatment group.  Study 
completion status and reasons for discontinuation will also be displayed.  The safety population 
will be used for these summaries.  Medical and surgical history and protocol 
violations/deviations will be presented in participant listings. 
10.4. 
Statistical Analyses 
Data from Part 1 will be included in the overall safety/tolerability summaries; however, 
participants in Part 1 will not be combined with those from Part 2 for the statistical inference 
performed in Part 2.  Sampling to assess plasma exposures to volixibat may be discontinued in 
Part 2 pending results in Part 1. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
87 
10.4.1. 
Efficacy Analyses 
10.4.1.1. Primary Efficacy Endpoint 
For Part 2, the primary efficacy endpoint analysis is defined as the mean change in total sBA 
concentration from baseline to Week 3.  
Primary Estimand for Primary Efficacy Endpoint 
The primary estimand efficacy endpoint is to evaluate the superior efficacy of volixibat versus 
placebo for the reduction of elevated sBA concentrations in participants with ICP.  The primary 
comparison of interest is the mean change in sBA concentration comparing baseline with 
Week 3.  The primary comparison will be made regardless of adherence to randomized 
treatment, treatment modification, or treatment termination and irrespective of any changes in or 
initiations of allowed concomitant therapies, while assuming that prohibited medications are not 
available.  
The corresponding primary estimand is described by the following 5 attributes: 
• Treatments:  The randomized treatment administered BID until delivery (with at least 
1 dose), regardless of adherence to randomized treatment, treatment modification, or 
treatment termination 
• Population:  Participants with ICP who have an sBA concentration ≥20 µmol/L and 
an average daily score of ≥4 on the Adult ItchRO during the screening period.  
Further population criteria details are provided in Sections 5.1 and 5.2. 
• Endpoint:  Change in the sBA concentration comparing baseline with Week 3 
• Population-level summary:  Difference in the mean change in the sBA concentration 
• Intercurrent events: 
o Change in or administration of any allowed concomitant medication will be 
handled using a treatment policy strategy. 
o Administration of any prohibited concomitant medication will be handled using a 
hypothetical strategy assuming that the prohibited medications are not available 
and hence were not taken, so as to assess the treatment effect for the randomized 
treatment groups on top of allowed concomitant medication. 
o Discontinuation of randomized treatment due to all of the following reasons will 
be handled using a treatment policy strategy: 
 Lack of efficacy 
 Safety concerns 
 Lack of compliance to study treatment 
o Delivery prior to 3 weeks of treatment will be handled using a hypothetical 
strategy, assuming that delivery has not occurred.  Few early deliveries are 
expected prior to Week 3.  Participants with sBA <100 are not likely to give birth 
prior to 39 weeks, which is at least 3 weeks after the first dose date based on 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
88 
eligibility criteria (see Section 8.1.12).  Participants with sBA >100 at 34 weeks 
would have been randomized at least a week earlier (i.e., 33 weeks) because a 
planned birth within 7 days of randomization is exclusionary.  It is anticipated that 
these participants would still be able to remain on treatment for 3 weeks before 
giving birth. 
o Perinatal death prior to 3 weeks of treatment will be handled using a hypothetical 
strategy, assuming perinatal death has not occurred.  Very few, if any, perinatal 
deaths are expected prior to Week 3. 
o Discontinuation of randomized treatment due to other reasons (including loss to 
follow-up) will be handled using a hypothetical strategy, assuming that 
randomized treatment had not been discontinued. 
o Liver transplant or death:  Neither of these are expected in the study.  In the 
unlikely event of this happening, they will be treated using a composite strategy, 
assuming worse case for all subsequent assessments. 
Primary Analysis for Primary Efficacy Endpoint 
The primary analysis on the primary efficacy endpoint will be conducted in Part 2 using the 
modified intent-to-treat (mITT) population.  A restricted maximum likelihood (REML)–based 
mixed-effects model for repeated measures (MMRM) will be used as the primary analysis 
method.  The repeated measures include weekly postbaseline visits through Week 3, with the 
change from baseline in total sBA as the dependent variable.  The MMRM model will include 
the fixed, continuous effects of baseline sBA and gestational age, fixed categorical effects of 
presence/absence of gestational diabetes, treatment group, visit, and treatment group-by-visit 
interaction and participant as a random effect.   
The unstructured variance/covariance matrix will be used to model the variances and covariances 
for the time points included in the model.  The unstructured variance/covariance does not impose 
any restrictions on the pattern of the matrix elements.  The use of an endpoint 3 weeks after 
baseline should result in minimal amounts of missing data.  Every attempt (e.g., relaxing the 
convergence criteria, increasing the iteration limit, choosing reasonable starting values for the 
estimates) will be made to ensure convergence using the unstructured modeling of 
within-participant correlations.  However, if the numerical algorithm for estimation of the mixed 
model fails to converge, the following variance/covariance matrix structures will be used in the 
following order:  1) heterogeneous Toeplitz, 2) heterogeneous compound symmetry, and 
3) heterogeneous autoregressive of order 1.  The first (co)variance structure that does not have a 
convergence problem will be the one used for the analysis.  The Kenward-Roger approximation 
(1997) will be used to estimate denominator degrees of freedom. 
The primary efficacy analysis will compare volixibat and placebo using the contrast (difference 
in least squares [LS] means) between treatment groups at Week 3.  Significance tests will be 
based on LS means using a 2-sided significance level (2-sided 95% CIs). 
The null hypothesis for the primary efficacy endpoint of the equality of volixibat and placebo is: 
H0:  mean change in total sBA baseline and Week 3 in the 2 treatment groups are 
equal 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
89 
The null hypothesis of equal treatment effect will be rejected if the statistical analysis results in a 
2-sided p-value for treatment at Week 3 is ≤0.05.  LS means will be calculated for each treatment 
group for each postbaseline visit in the model.  The difference between volixibat and placebo 
change from baseline in sBA will be estimated, with the corresponding 2-sided 95% CI 
constructed for each visit through Week 3.  The change from baseline LS means with SE, 95% 
CI for the LS means, p-value for testing if the LS mean is zero, LS mean difference between 
treatment groups (volixibat minus placebo) with SE, 95% CI for the LS mean difference, and 
p-value for testing if the treatment LS means are equal will be presented. 
The study will be claimed successful if the hypothesis of no treatment effect on the primary 
efficacy endpoint over Part 2, in the mITT population is rejected at the 0.05 (2-sided) 
significance level. 
Separately, a similar analysis on each of the open-label cohorts will be performed.  The analysis 
will be identical, except that baseline sBA will not be a covariate used within the model. 
Rationale for Primary Analysis Method 
The MMRM method has been demonstrated extensively as an appropriate choice for the primary 
analysis in longitudinal confirmatory clinical studies with continuous endpoints 
(Mallinckrodt et al. 2008).  This analysis method, which is from a broader class of 
direct-likelihood analyses methods, makes use of fully and partially observed data sequences 
from individual participants by estimating the covariance between data from different time points 
(Molenberghs and Kenward 2007).  Further, it is often useful to implement MMRM using an 
unstructured approach to modeling both the treatment-by-time means and the (co)variances, 
leading to what is essentially a multivariate normal model wherein treatment group means at the 
primary time point are adjusted to reflect both the actual observed data and the projected 
outcomes from the participants with missing data (Cnaan et al. 1997; Molenberghs et al. 2004; 
Molenberghs and Kenward 2007). 
Despite careful planning and study conduct, the occurrence of missing data cannot be completely 
eliminated.  As a direct likelihood method, the MMRM method is a preferred approach for 
handling missing data in such designs.  MMRM is a full multivariate model in nature that avoids 
potential bias as a predetermined model and operates in a more general missing at random 
(MAR) framework (Mallinckrodt et al. 2001).  Data are considered MAR if, conditional upon the 
independent variables in the analytic model, the missingness depends on the observed outcomes 
of the variable being analyzed but does not depend on the unobserved outcomes of the variable 
being analyzed.  This assumption implies that the behavior of the post-dropout observations can 
be predicted from the observed variables and therefore that treatment effect can be estimated 
without bias with use of the observed data (EMA 2010).  For studies of missing data in a 
controlled clinical study setting, MAR is usually considered as a plausible underlying missing 
mechanism (Molenberghs and Kenward 2007; Siddiqui et al. 2009; Mallinckrodt et al. 2008, 
2013).  The assumption of MAR is often reasonable because, particularly in longitudinal studies 
wherein the evolution of treatment effects is assessed by design over time, the observed data and 
the models used to analyze them can explain much of the missingness (Little and Rubin 1987; 
Verbeke and Molenberghs 2000).  This point may be especially relevant in well-controlled 
studies, in which extensive efforts are made to observe all outcomes and factors that influence 
them while participants are following protocol-defined procedures.  Thus, longitudinal clinical 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
90 
studies by their very design aim to reduce the amount of missing not at random (MNAR) data 
(missingness explained by unobserved responses), thereby increasing the plausibility of MAR 
(Mallinckrodt et al. 2008). 
Sensitivity and Supportive Analysis for Primary Efficacy Endpoint 
Sensitivity and supportive analysis will be performed on the primary efficacy endpoint to 
quantify the possible impact of missing data and to demonstrate the robustness of the 
conclusions.  See below for details about missing data handling, placebo-based imputation, and a 
tipping-point analysis. 
Furthermore, the primary analysis will be repeated using a hypothetical (de jure) estimand where 
data collected after rescue medication is initiated will be omitted.  This can be viewed as 
addressing a per protocol estimand, or more simply the applicable estimand if all participants 
completed the first 3 weeks of follow-up without any rescue or without any missing data. 
Summary statistics on total sBA by treatment group and visit will also be presented.  In addition, 
a figure with the LS mean ±SE of change from baseline in total sBA will be presented by 
treatment group and visit. 
In addition, a responder analysis (based on change in total sBA) may be considered.  The 
response definition and its appropriate analysis methodology will be outlined in the SAP. 
Missing Data 
Although the assumption of MAR, as used for the primary efficacy analysis method, is often 
reasonable in clinical studies, the possibility of MNAR data cannot be ruled out.  Therefore, 
analysis valid under MNAR is desired.  Both a MNAR- and MAR-based analyses will be the 
basis upon which sensitivity of missing data is assessed. 
Sensitivity analyses to deal with missing data will use multiple imputation (MI) methods where 
missing values are imputed individually under both a plausible MNAR and MAR scenario.  MI 
is a simulation-based approach where missing values are replaced using an appropriate stochastic 
model given the observed data and covariates, creating multiple completed datasets.  These 
completed datasets are then analyzed using standard analysis methods (i.e., MMRM), and the 
different parameter estimates across the datasets are then combined to produce a unique point 
estimate and SE taking into account the uncertainty of the imputation process.  The following 
2 sensitivity analysis models, one based on the standard MAR approach and the other based on 
the MNAR approach, will be used to examine robustness of the primary analysis results.  
Complete details of the MI procedures, including the methodology, number of imputations, and 
the seed of the pseudorandom number generator used to randomly generate imputations for the 
missing values, will be prespecified in the SAP prior to unblinding. 
Standard MAR Imputation 
The MAR imputation model will impute missing values using a regression-based MI model 
(Little and Yau 1996).  For participants with complete data up to a particular visit, a multiple 
regression model will be fit that includes the outcome at that visit as the dependent variable and 
observed data (e.g., outcomes at previous visits, treatment, and baseline) as independent 
variables.  Separate models will be similarly constructed for each visit.  Using these regression 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
91 
models, a missing value for a participant at a particular visit will be imputed as a draw from the 
predictive distribution given the outcomes at previous visits (some possibly imputed), treatment 
group, etc.  This process will be repeated a given number of times (as specified in the SAP), 
resulting in the same number of complete analysis datasets.  The MMRM analyses will be 
performed separately for each of the completed analysis datasets, and the results will be 
combined into 1 MI inference (Little and Yau 1996; Schafer 1997).  This strategy is appropriate 
for datasets that have a monotone missing data pattern.  If the dataset does not precisely have this 
pattern, a monotone data augmentation method, as described in the SAP, will be used to impute 
the small amount of missing data that is required to make the missing data pattern monotone 
before applying the MI algorithm described above. 
Placebo-Based Imputation 
The placebo-based imputation analysis model assumes a MNAR mechanism and is within the 
pattern-mixture model framework.  The pattern-mixture model approach models the distribution 
of a response as the mixture of a distribution of the observed responses and a distribution of the 
missing responses.  Conceptually, pattern mixture models typically assess the outcome variable 
separately for different groups (patterns) and then combine results across groups for final 
inference (Mallinckrodt et al. 2008; Ratitch and O’Kelly 2011).  The pattern-mixture model 
approach will be applied in the SAS MI procedure by using the MNAR statement.  The MNAR 
imputation model will specify a subset of observations to derive the imputation model, which is 
used for pattern imputation based on the placebo group. 
The underlying assumption is that a participant on the active treatment with missing data follows 
the distribution of the placebo responses (i.e., the means and the intra-participant correlations 
based on the placebo responses will apply).  This sensitivity analysis stress-tests the MAR 
assumption that withdrawals will tend to have efficacy similar to participants who remain in the 
study in their respective treatment arm.  On the contrary, the placebo-based pattern imputation 
assumes MNAR; that after discontinuation, participants on study drug will tend to have efficacy 
close to participants on placebo. 
The imputations for this model are based on the distribution of placebo group responses over 
time.  That is, an imputation model for the missing observations in the volixibat treatment group 
is constructed not from the observed data in the active treatment group but rather from the 
observed data in the placebo treatment group.  This model is also the imputation model that is 
used to impute missing observations in the placebo group. 
Tipping Point Analysis 
An additional sensitivity analysis using the tipping-point approach will be conducted to assess 
the robustness of the primary analysis approach.  If it is plausible that, for the active treatment 
group, the distribution of missing primary endpoint responses has a smaller expected reduction 
than that of the corresponding distribution of the observed primary endpoint responses, the 
conclusion under the MAR assumption should be examined.  It is desired to impose a fixed and 
definite set of quantities to encapsulate the change in efficacy associated with withdrawal 
(missing) for the active treatment group and independently for the placebo group.  The tipping 
point MI analysis as described by Ratitch et al. (2013) will be applied.  Tipping point analysis is 
a means of exploring the influence of missingness on the overall conclusion from statistical 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
92 
inference by positing a wide spectrum of specifications regarding the missingness mechanism 
(from less pessimistic to more pessimistic).  The analysis finds a (tipping) point in this spectrum 
of specifications, at which conclusions change from being favorable to the experimental 
treatment to being neutral.  After such a tipping point is determined, clinical judgment can be 
applied as to the plausibility of the specifications underlying this tipping point.  The tipping point 
can be identified while the result is no longer statistically significant.  This imputation analysis 
uses a specified sequence of shift parameters, which adjust the imputed values for observations 
in the active treatment group and independently for the placebo group.   
10.4.1.2. Adjustment for Multiplicity 
In order to maintain study-wide Type I error control, an hierarchical testing procedure will be 
used in the comparisons between volixibat and placebo on the primary and secondary efficacy 
endpoints in the mITT population.  The hierarchical order for testing the null hypotheses is as 
follows:  1) mean change in total sBA between baseline and Week 3, 2) mean change in Adult 
ItchRO between baseline and Week 3, and 3) the proportion of participants experiencing a 
composite perinatal outcome.   
The effect of such a procedure is that no confirmatory claims can be based on the endpoint(s) 
that have a rank lower than that endpoint whose null hypothesis was the first that could not be 
rejected.  Those tests will be considered as exploratory without any formal conclusions drawn 
about them. 
The analysis of Part 1 will be considered separate from Part 2 and no multiplicity control will be 
made. 
10.4.1.3. Secondary Efficacy Endpoints 
The secondary efficacy endpoints (see Section 3.2) are designed to evaluate the efficacy of 
volixibat versus placebo for the treatment of pruritus in participants with ICP as well as 
composite perinatal outcomes. 
The secondary efficacy endpoint for pruritus is defined as the mean change from baseline to 
Week 3 in the weekly average worst daily itch score as measured by the Adult ItchRO.  The 
worst daily itch score is averaged over the 7 days preceding baseline and over the 7 days 
preceding each week through Week 3.  If >3 days of assessments are missing from a given week, 
then that weekly average will be set to missing.  The analysis of the Adult ItchRO will use an 
MMRM with a comparable model to that for the primary endpoint.  The primary comparison will 
be made regardless of adherence to randomized treatment, treatment modification, or treatment 
termination and irrespective of any changes in, or initiations of, allowed concomitant therapies, 
while assuming prohibited medications are not available and that delivery or perinatal death prior 
to 3 weeks does not occur. 
The attributes for this estimand are the same as for the primary estimand except for the below: 
• Endpoint:  Change from baseline to Week 3 of the study treatment period in the 
weekly averaged worse daily itch score as measured by the Adult ItchRO (average of 
the 7 days preceding baseline and of the 7 days preceding Week 3). 
• Population-level summary:  Difference in the mean change in the weekly averaged 
worse daily itch score 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
93 
The secondary efficacy endpoint for composite perinatal outcomes is defined as the proportion of 
participants that experience any of the 4 outcomes specified in Section 3.2.  The comparison of 
interest is the proportion of participants meeting the composite outcome.  The primary 
comparison will be made regardless of adherence to randomized treatment, treatment 
modification, or treatment termination and irrespective of any changes in, or initiations of, 
allowed concomitant therapies, while assuming prohibited medications are not available. 
The attributes for this estimand are the same as for the primary estimand except for the below: 
• Treatments:  The randomized treatment administered BID until day of delivery (with 
at least 1 dose), regardless of adherence to randomized treatment, treatment 
modification, or treatment termination. 
• Endpoint:  Experiencing one or more of perinatal death, spontaneous preterm 
delivery, iatrogenic preterm delivery attributed to ICP or ICP-related complications, 
neonatal unit admission for ≥12 hours from birth until hospital discharge for one or 
more of predefined indications. 
• Population-level summary:  Difference between treatment groups in the proportion of 
participants achieving the endpoint. 
• Intercurrent events:  Preterm delivery or perinatal death are included as part of the 
endpoint definition and thus handled using a composite strategy. 
For this responder-type endpoint, the number and proportion of participants that are considered a 
“responder” will be summarized by treatment group at Week 3 and analyzed using a stratified 
Cochran-Mantel-Haenszel (CMH) test to calculate the p-value for the difference between 
treatment groups.  The p-value from the CMH test will be the basis of the hypothesis testing.  
Furthermore, as supportive analyses, a Logistic Regression (LR) estimator approach 
(Ge et al. 2011), as well as a logistic regression model with baseline sBA, gestational age, and 
presence/absence of gestational diabetes as covariates will be run.  The model assumptions of the 
logistic regression model are not considered a concern because a randomized study has 
comparable distributions of the treatment groups for covariates and factors for stratification, 
although they may impact the interpretation of estimated parameters for the covariates.  Most 
importantly, a logistic regression model addresses estimands that are conditional on the 
covariates in the model, with these estimands sometimes being called participant-specific, and 
express the extent of efficacy of a treatment that a participant might expect on the basis of her 
covariates, although they tend to be further from the null for an effective treatment than 
population average estimand.  A randomization-based version of logistic regression will also be 
considered.  It is robust to model assumptions, and it has a population average estimand that is 
the same as the unadjusted OR for comparing 2 treatments (Zinc and Koch 2012). 
An hierarchical testing procedure, as described in Section 10.4.1.2, will be used in the 
comparisons between volixibat and placebo on the primary and secondary efficacy endpoints for 
Part 2 in the mITT population using the primary analysis method (as described for the primary 
endpoint).  Sensitivity analyses for the secondary endpoints included within the hierarchical 
testing procedure will be detailed within the SAP. 
All tests will be performed as 2-sided tests at the 0.05 level of significance. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
94 
10.4.1.4. Exploratory Efficacy Endpoints 
The exploratory efficacy endpoints are defined in Section 3.4.  The change in total sBA from 
Week 3 (primary endpoint) to delivery will be considered, and the difference between treatment 
groups will be tested using a randomization-based version of rank analysis of covariance 
(ANCOVA; Stokes et al. 2012).  In a similar manner, the change from baseline in total sBA 
concentration to the time of delivery will also be explored.  An additional analysis will be 
performed that examines the change from baseline to delivery but that averages across the last 
2 time points on or prior to delivery.  Similar analyses will be performed for Adult ItchRO.  
Associations between the changes from baseline to Week 3 in total sBA and Adult ItchRO will 
be assessed using either Pearson’s or Spearman’s correlation coefficient.  “Responder” analyses 
for composite perinatal outcomes will be performed using baseline sBA and ItchRO and the 
change at Week 3 values in sBA and ItchRO as covariates and, separately, using the Week 3 
values themselves (instead of the change at Week 3). 
Change in biomarkers of bile acid synthesis, inflammation, and pruritogens as well as the 
proportion of participants with sBA <40 μmol/L at the end of the treatment period will also be 
explored.  The change in biomarkers will follow the same approach as other exploratory efficacy 
endpoints described above.  The proportion of participants with sBA <40 μmol/L at the end of 
the treatment period will be analyzed in the same manner as the secondary efficacy endpoint for 
composite perinatal outcomes. 
Further exploratory efficacy endpoints include continuous and binary endpoints on additional 
perinatal outcomes.  The analysis of continuous endpoints will follow the same approach as other 
exploratory efficacy endpoints described above.  Binary outcomes will be analyzed in the same 
manner as the secondary efficacy endpoint for composite perinatal outcomes.  Additional details 
will be included within the SAP. 
The secondary endpoint of composite perinatal outcomes will also be explored using an ordinal 
scale, with ranks assigned according to the severity of the outcomes specified within Section 3.2.   
Table 4 
Perinatal Outcome Severity Scoring 
Perinatal Outcome 
Score 
Perinatal death 
4 
Spontaneous preterm delivery 
3 
Iatrogenic preterm delivery attribute to ICP or ICP-related complications 
2 
Neonatal unit admission for ≥12 hours from birth until hospital discharge for 
any of the reasons listed in Section 3.2 
1 
No perinatal outcome 
0 
ICP=intrahepatic cholestasis of pregnancy. 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
95 
The score is assigned according to the most severe outcome following the order shown above.  If 
a participant experiences perinatal death, spontaneous preterm delivery, or iatrogenic preterm 
delivery attributed to ICP or ICP-related complications AND neonatal unit admission for 
≥12 hours from birth until hospital discharge for any of the reasons listed in Section 3.2, the 
score will be adjusted by 0.5.  For example, if a participant has spontaneous preterm delivery 
followed by a neonatal unit admission, the score would be 3+0.5=3.5, where the 3 comes from 
the spontaneous preterm delivery and the 0.5 comes from the fact that neonatal unit admission 
occurred.  This will be analyzed using a stratified log rank test that provides more weight to the 
more severe outcomes and will employ a randomization-based covariance adjustment 
(Zinc and Koch 2012).  
Additional, nonefficacy exploratory endpoints are described within Section 10.4.3. 
10.4.2. 
Safety Analyses 
All safety analyses will be performed on the safety population, defined as all participants who 
were randomized and received at least 1 dose of study medication. 
For all safety and tolerability analyses, participants will be analyzed by the treatment received 
and the overall active treatment group.  For active treatment, the dose received will be used.  
Safety data collected at the baseline visit or the last preceding visit (if not collected at the baseline 
visit) will be used as the baseline value for safety analyses. 
Safety measures include AEs, clinical laboratory values, physical examination findings 
(including body weight, height, and BMI), vital signs, and concomitant treatment usage.  For 
quantitative variables, descriptive statistics including number of observations, mean, median, 
standard deviation, minimum, and maximum will be presented for observed and change from 
baseline values at each study visit.  Qualitative variables will be summarized using counts and 
percentages. 
Beyond the endpoints described within Section 3, any additional fetal data collected will only be 
listed.  These include but are not limited to fetal ultrasounds and antepartum fetal monitoring via 
NST/CTG, BPP, and fetal heart rate auscultation.  
All safety and tolerability data will be presented in listings. 
10.4.2.1. Adverse Events 
In general, TEAEs are defined as AEs that start or deteriorate on or after the first dose of study 
medication and no later than 7 days following the last dose of study medication.  For any 
participants (i.e., expectant mothers) who die during the study and the date of death is between 
the date of the first dose of study medication and the date of study discontinuation (as entered by 
the site), inclusive, all AEs (including those resulting in death) that occur during the study will be 
considered as TEAEs irrespective of the last dose and will be included in the TEAE summaries.  
All summaries of AEs will be based on TEAEs unless specified otherwise. 
The complete list of Preferred Terms for AESIs and ECIs (as described in Sections 9.2.6 and 
9.2.7) will be outlined in the SAP and summarized. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
96 
AEs will be coded using MedDRA.  The number and proportion of participants who experience 
the event according to MedDRA System Organ Class (SOC) and Preferred Term will be 
presented by treatment group.  
The incidence of all AEs and treatment-related AEs will be tabulated by treatment received.  
These AEs will be classified by SOC and Preferred Term using MedDRA.  AEs will be graded 
using the CTCAE, Version 5.0, grading scale.  For incidence reporting, if a participant reported 
>1 AE that was coded to the same SOC or Preferred Term, the participant will be counted only 
once for that specific SOC or Preferred Term.  An overview of AEs and TEAEs, both of which 
include participant incidence of AEs, treatment-related AEs, AEs by severity, AESIs, ECIs, 
SAEs, deaths, and AEs that lead to discontinuation, will be presented.  
Furthermore, exposure-adjusted incidence rates (EAIR) will be provided for each AE reported.  
For EAIR analyses, the following convention will be used to calculate the denominator (i.e., 
population-level time at-risk) for these analyses.  The population-level time at-risk includes only 
the time each participant is at risk.  The start date of at-risk time is the date of first dose of study 
drug, and the last date of at-risk time is the start date of the occurrence of the AE or is censored 
at completion/early termination, whichever is earlier. 
While no formal hypothesis testing or margin selection is planned, the risk difference and 
corresponding exact 95% CI (using the method of Chan and Zhang [1999]) will be presented to 
compare treatment groups with regards to AESIs and ECIs. 
Participant listings of AEs will include the dose of study medication at the onset of the event. 
10.4.2.2. Vital Signs and Weight/Height Measurements 
Vital signs (temperature, systolic and diastolic blood pressure, heart rate, and respiratory rate), 
weight, height, and BMI will be summarized descriptively by study visit and treatment group as 
observed and the change from baseline values. 
10.4.2.3. Laboratory Assessments 
Clinical safety laboratory values will be measured by a central laboratory and, where grading 
criteria apply, will be graded according to the CTCAE grading scale.  Summary statistics for 
actual values and for changes from baseline will be tabulated for laboratory results by scheduled 
visit.  Graphs of laboratory values over time may also be produced. 
Participants with clinical laboratory values outside of the normal reference range at any 
postbaseline assessment will be summarized, including by the CTCAE and, if necessary, other 
grading scales.  Shifts from baseline laboratory values will be tabulated.  The observed vital sign 
data, the change from baseline, and those meeting criteria for potentially clinically significantly 
abnormal criteria for each measurement will be summarized with descriptive statistics. 
10.4.2.4. Prior and Concomitant Treatments 
Prior and concomitant treatments will be summarized descriptively by treatment group with the 
number and proportion of participants. 
Prior medications will be presented separate from concomitant treatments.  Medications that 
started prior to the first dose of study medication will be considered prior medications regardless 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
97 
of whether they were stopped prior to the first dose of study medication.  Any medications 
continuing or starting after the first dose of study medication will be considered to be 
concomitant.  If a medication starts prior to the first dose of study medication and continues after 
the first dose of study medication, it will be considered both prior and concomitant. 
Medications will be coded using the World Health Organization Drug Dictionary. 
10.4.3. 
Other Analyses 
10.4.3.1. Patient-Reported Outcomes 
The effect of volixibat on additional measures of pruritus efficacy and quality of life in adult 
participants with ICP will be evaluated via the following endpoints: 
• Change from baseline in the 5-D Itch Scale 
• Change from baseline in CSS 
• Change from baseline in EQ-5D-5L  
• Change from baseline in PROMIS SF Fatigue 7a  
• Change from baseline in PROMIS SF Sleep Disturbance 
• Change from baseline in PIS-Itch 
Because the PROs are administered only at baseline, Week 3, and end of treatment, the change 
from baseline will be compared between the 2 groups with use of rank ANCOVA with 
adjustment for baseline with the Mann-Whitney odds as the estimand.  The estimates and CIs can 
be calculated using the R package sanon (Kawaguchi and Koch 2015). 
10.4.3.2. Healthcare Utilization 
Healthcare resource utilization variables include the number and duration of medical care 
encounters, including surgeries and other selected procedures (inpatient and outpatient), the dates 
and duration of hospitalization (total days or length of stay, including duration by wards [e.g., 
intensive care unit]), the number and type of diagnostic and therapeutic tests and procedures, and 
outpatient medical encounters and treatments (including physician or emergency department 
visits, tests and procedures, and medications).  Descriptive statistics including number of 
observations, mean, 95% CI on the mean, median, minimum, and maximum will be presented by 
visit for continuous variables.  For categorical variables, the number and proportion of 
participants will be presented. 
10.4.3.3. Pharmacokinetic Analyses 
For maternal volixibat plasma concentration assessments:  Plasma concentration of volixibat 
near predicted maximum observed concentration (Cmax) will be obtained during the Week 1 visit, 
~3 hours after dosing.  Trough plasma levels of volixibat will be obtained during the Week 3 
visit before dosing.  Contingent upon meaningful exposures of volixibat, PK endpoints may 
include but are not limited to Cmax, time to reach Cmax (Tmax), and the AUC from time zero to the 
last measurable time point.  Actual dosing and sampling times will be used for calculation of PK 
parameters.  Additional PK parameters may be calculated.  


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
98 
For fetal (umbilical cord) volixibat plasma concentration assessments:  Plasma concentration of 
volixibat in the umbilical cord blood sample obtained at delivery will be collected (when 
possible) and analyzed. 
10.4.4. 
Interim Analysis 
A formal interim analysis will be conducted at the end of Part 1, which will inform sample size 
for Part 2 as well as dose selection.  There will be ongoing data review during Part 1 after every 
~20 participants are enrolled in this open-label setting.  Data from Part 1 will be included in the 
overall safety and tolerability summaries but will not be combined with those from Part 2 for the 
statistical inference performed in Part 2.   
11. 
REGULATORY, ETHICAL, AND STUDY OVERSIGHT 
CONSIDERATIONS 
11.1. 
Regulatory and Ethical Considerations 
This study will be conducted in accordance with the protocol and with the following: 
• Consensus ethical principles derived from international guidelines including the 
Declaration of Helsinki and Council for International Organizations of Medical 
Sciences International Ethical Guidelines 
• Applicable International Council for Harmonisation of Technical Requirements for 
Pharmaceuticals for Human Use (ICH) Good Clinical Practice (GCP) Guidelines 
• Applicable laws and regulations 
The protocol, protocol amendments, ICF, IB, and other relevant documents (e.g., advertisements) 
must be submitted to an IRB/IEC by the investigator and reviewed and approved by the IRB/IEC 
before the study is initiated at the investigator’s site. 
Any amendments to the protocol will require IRB/IEC approval before implementation of 
changes made to the study design, except for changes necessary to eliminate an immediate 
hazard to study participants. 
The investigator will be responsible for the following: 
• Providing written summaries of the status of the study to the IRB/IEC annually or 
more frequently in accordance with the requirements, policies, and procedures 
established by the IRB/IEC 
• Notifying the IRB/IEC of SAEs or other significant safety findings as required by 
IRB/IEC procedures 
• Providing oversight of the conduct of the study at the site and adherence to 
requirements of 21 CFR, ICH guidelines, the IRB/IEC, European regulation 536/2014 
for clinical studies (if applicable), and all other applicable local regulations 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
99 
11.2. 
Financial Disclosure 
Investigators and subinvestigators will provide the sponsor with sufficient, accurate financial 
information as requested to allow the sponsor to submit complete and accurate financial 
certification or disclosure statements to the appropriate regulatory authorities.  Investigators are 
responsible for providing information on financial interests during the course of the study and for 
1 year after completion of the study. 
11.3. 
Informed Consent Process 
The investigator or his or her representative will explain the nature of the study to the participant 
and answer all questions regarding the study. 
Participants must be informed that their participation is voluntary.  Participants will be required 
to sign a statement of informed consent that meets the requirements of 21 CFR 50, local 
regulations, ICH guidelines, Health Insurance Portability and Accountability Act (HIPAA) 
requirements, where applicable, and the IRB/IEC or study center.  If required by local laws 
and/or regulations, paternal consent may also be required on behalf of the fetus. 
The medical record must include a statement that written informed consent was obtained before 
the participant was enrolled into the study and the date the written consent was obtained.  The 
authorized person obtaining the informed consent must also sign the ICF. 
Participants must be reconsented to the most current version of the ICF during their participation 
in the study. 
The investigator must maintain the original, signed ICF.  A copy of the ICF must be provided to 
the participant. 
The ICF will contain a separate section that addresses the use of any remaining mandatory 
samples for optional exploratory research.  The investigator or authorized designee will explain 
to each participant the objectives of the exploratory research.  Participants will be told that they 
are free to refuse to participate and may withdraw their consent at any time and for any reason 
during the storage period.  A separate signature will be required to document a participant's 
agreement to allow any remaining specimens to be used for exploratory research.  Participants 
who decline to participate in this optional research will not provide this separate signature but are 
still eligible for Study VLX-401. 
11.4. 
Data Protection 
Participants will be assigned a unique identifier by the sponsor.  Any participant records or 
datasets that are transferred to the sponsor will contain the identifier only; participant names or 
any information that would make the participant identifiable will not be transferred. 
The participant must be informed that her personal study-related data will be used by the sponsor 
in accordance with local data protection laws.  The level of disclosure must also be explained to 
the participant. 
The participant must be informed that her medical records may be examined by Quality 
Assurance auditors or other authorized personnel appointed by the sponsor, by appropriate 
IRB/IEC members, and by inspectors from regulatory authorities. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
100 
11.5. 
Committee Structure 
11.5.1. 
Independent Data Monitoring Committee 
An IDMC will be formed to monitor the study for safety, ethical conduct, and scientific 
soundness; to review the efficacy interim analyses during the study; and to make 
recommendations to the sponsor regarding further conduct of the study, including a 
recommendation regarding whether the study should be continued, revised, or terminated.  The 
IDMC will be comprised of physicians with expertise in the care and interpretation of studies of 
ICP and similar liver conditions, and a voting clinical statistician with experience in similar 
indications.  The function of the IDMC will be documented in the IDMC Charter, which will be 
ratified by signature of all voting members.  The first IDMC meeting (post-study start) will be 
held after 12 participants in Part 2 have completed the study; cadence for future meetings, along 
with AE monitoring specifications and additional detail regarding procedures, will be outlined in 
the IDMC charter.  IDMC minutes and recommendations will be provided to the regulatory 
authorities upon request.   
11.6. 
Publication Policy 
The results of this study may be published or presented at scientific meetings.  If this is foreseen, 
the investigator agrees to submit all manuscripts or abstracts to the sponsor before submission.  
This allows the sponsor to protect proprietary information and to provide comments. 
The sponsor will comply with the requirements for publication of study results.  In accordance 
with standard editorial and ethical practice, the sponsor will generally support publication of 
multicenter studies only in their entirety and not as individual site data.   
11.7. 
Dissemination of Clinical Study Data 
In accordance with the US Food and Drug Administration Amendments Act of 2007 and the 
European Medicines Agency clinical study Directive 2001/20/EC, the sponsor is solely 
responsible for determining whether the study and its results are participant to the requirements 
for submission to www.clinicaltrials.gov, www.clinicaltrialsregister.eu, or other local registries.  
The sponsor will submit the information necessary to fulfill the requirements.  By signing the 
protocol, the investigator agrees to not submit any information about this study or its results to 
the registries. 
11.8. 
Data Quality Assurance 
All participant data relating to the study will be recorded on printed or eCRFs unless transmitted 
to the sponsor or designee electronically (e.g., laboratory data).  The investigator is responsible 
for verifying that data entries are accurate and correct by physically or electronically signing the 
eCRF. 
The investigator must maintain accurate documentation (source data) that supports the 
information entered into the eCRF. 
The investigator must permit study-related monitoring, audits, IRB/IEC review, and regulatory 
agency inspections and provide direct access to source data documents. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
101 
The sponsor or designee is responsible for the data management of this study, including quality 
checking of the data. 
The sponsor assumes accountability for actions delegated to other individuals (e.g., CROs). 
Study monitors will perform ongoing source data verification to confirm that data entered into 
the eCRF by authorized site personnel are accurate, complete, and verifiable from source 
documents; that the safety and rights of participants are being protected; and that the study is 
being conducted in accordance with the currently approved protocol and any other study 
agreements, ICH GCP, and all applicable regulatory requirements. 
Records and documents, including signed ICFs, pertaining to the conduct of this study must be 
retained by the investigator in accord with country-specific requirements for at least 25 years 
after completion or discontinuation of the study, or at least 2 years after the last approval of a 
marketing application in an ICH region and until there are no pending or contemplated marketing 
applications in an ICH region for the drug for the indication for which it is being investigated, or 
at least 2 years after formal discontinuation of clinical development of the investigational 
product, whatever is the longest.  No records may be destroyed during the retention period 
without the written approval of the sponsor.  No records may be transferred to another location 
or party without written notification to and acceptance by the sponsor. 
To ensure compliance with GCP and all applicable regulatory requirements, the sponsor may 
conduct a quality assurance audit.  Refer to Section 11.10 for more details regarding the audit 
process. 
11.9. 
Study Monitoring 
Before an investigational site can enter a participant into the study, a representative of the 
sponsor will perform a site qualification visit to: 
• Determine the adequacy of the facilities 
• Discuss with the investigator(s) and other personnel their responsibilities with regard 
to protocol adherence and the responsibilities of the sponsor or its representatives.  
This will be documented in a clinical study agreement between the sponsor and the 
investigator. 
During the study, a monitor from the sponsor or representative will have regular contacts with 
the investigational site for the following: 
• Provide information and support to the investigator(s) 
• Confirm that facilities remain acceptable 
• Confirm that the investigational team is adhering to the protocol, data are being 
accurately recorded in the eCRF, and investigational product accountability checks 
are being performed 
• Perform source data verification.  This includes a comparison of the data in the 
eCRFs with the participant’s medical records at the hospital or practice and other 
records relevant to the study.  This will require direct access to all original records for 
each participant (e.g., clinic charts) 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
102 
• Record and report any protocol deviations not previously sent to the sponsor or 
designee 
• Confirm that AEs and SAEs have been properly documented in the eCRFs, confirm 
that any SAEs have been forwarded to the sponsor, and confirm that those SAEs that 
met criteria for reporting have been forwarded to the IRB/IEC 
The sponsor or designee, including medical monitor, will be available between visits if the 
investigator(s) or other staff need information or advice. 
11.10. 
Audits and Inspections 
Authorized representatives of the sponsor, a regulatory authority, an IEC, or IRB may visit the 
site to perform audits or inspections, including source data verification.  The purpose of a 
sponsor audit or inspection is to systematically and independently examine all study-related 
activities and documents to determine whether these activities were conducted and whether data 
were recorded, analyzed, and accurately reported according to the protocol, ICH GCP guidelines, 
and any applicable regulatory requirements.  The investigator should contact the sponsor 
immediately if contacted by a regulatory agency about an inspection. 
The sponsor will be allowed to conduct site visits to the investigation facilities for the purpose of 
monitoring any aspect of the study.  The investigator agrees to allow the monitor to inspect the 
drug storage area, study drug stocks, drug accountability records, participant charts, study source 
documents, and other records relative to study conduct. 
11.11. 
Institutional Review Board/Independent Ethics Committee 
The investigator must obtain IRB/IEC approval for the investigation.  Initial IRB/IEC approval 
and all materials approved by the IRB/IEC for this study, including the participant ICF and 
recruitment materials, must be maintained by the investigator and made available for inspection. 
11.12. 
Data Handling and Recordkeeping 
11.12.1. 
Retention of Records 
The investigator must maintain all documentation relating to the study according to ICH GCP 
requirements and in accordance with local country-specific regulations and may not be destroyed 
without written permission from the sponsor.  If it becomes necessary for the sponsor or the 
regulatory authority to review any documentation relating to the study, the investigator must 
permit access to such records.  
11.12.2. 
Source Documents 
Source documents provide evidence for the existence of the participant and substantiate the 
integrity of the data collected.  Source documents are filed at the investigator’s site. 
Data reported on the eCRF or entered into the eCRF that are transcribed from source documents 
must be consistent with the source documents or the discrepancies must be explained.  The 
investigator may need to request previous medical records or transfer records, depending on the 
study.  Current medical records must be available. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
103 
11.13. 
Study and Site Closure 
The sponsor reserves the right to close the study site or terminate the study at any time for any 
reason at the sole discretion of the sponsor.  Study sites will be closed upon study completion.  A 
study site is considered closed when all required documents and study supplies have been 
collected and a study-site closure visit has been performed. 
Reasons for the early closure of a study site by the sponsor or investigator may include the 
following: 
• Failure of the investigator to comply with the protocol, the requirements of the 
IRB/IEC or local health authorities, the sponsor's procedures, or GCP guidelines 
• Inadequate recruitment of participants by the investigator 
• Discontinuation of further study drug development 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
104 
12. 
REFERENCES 
ACOG. Medically indicated late-preterm and early-term deliveries. Obstet Gynecol 
2019;133:e151–5. 
Al-Dury S, Marschall HU. Ileal bile acid transporter inhibition for the treatment of chronic 
constipation, cholestatic pruritus, and NASH. Front Pharmacol 2018;9:931. 
Bachs L, Pares A, Elena M, et al. Effects of long-term rifampicin administration in primary 
biliary cirrhosis. Gastroenterol 1992;102:2077–80. 
Bacq Y, Sapey T, Brechot M, et al. Intrahepatic cholestasis of pregnancy: a French prospective 
study. Hepatol 1997;26:358–64. 
Bergasa NV. Pruritus of cholestasis. In: Carstens E, Akiyama T, editors. Itch: mechanisms and 
treatment. Boca Raton (FL): CRC Press/Taylor & Francis; 2014. Chapter 6. 
Bergman H, Melamed N, Koren G. Pruritus in pregnancy: treatment of dermatoses unique to 
pregnancy. Can Fam Physician 2013;59:1290–4. 
Bicocca MJ, Sperling JD, Chauhan SP. Intrahepatic cholestasis of pregnancy: review of six 
national and regional guidelines. Eur J Obstet Gynecol Reprod Biol 2018;231:180–7. 
Boonstra K, Beuers U, Ponsioen CY. Epidemiology of primary sclerosing cholangitis and 
primary biliary cirrhosis: a systematic review. J Hepatol 2012;56:1181–8. 
Bowlus CL, Eksteen B, Cheung A, et al. Safety and efficacy of maralixibat in patients with 
primary sclerosing cholangitis: an open-label proof-of-concept study. The Liver Meeting 
[poster]. 2019 November 8–12. Available from: https://mirumpharma.com/wp-
content/uploads/2019/11/CAMEO_ePoster_file.pdf. 
[CDC] Center for Disease Control and Prevention. Alcohol use in pregnancy. Available at:  
https://www.cdc.gov/ncbddd/fasd/alcohol-use.html. Assessed 30 April 2020.  
Cella D, Pickard AS, Duh MS, et al. Health-related quality of life in patients with advanced renal 
cell carcinoma receiving pazopanib or placebo in a randomised phase III trial. Eur J Cancer 
2012;48:311–23. 
Chan ISF, Zhang Z. Test-based exact confidence intervals for the difference of two binomial 
proportions. Biometrics 1999;55:1202–9. 
Chappell LC, Bell JL, Smith A, et al. Ursodeoxycholic acid versus placebo in women with 
intrahepatic cholestasis of pregnancy (PITCHES): a randomised controlled trial. Lancet 
2019;394:849–60. 
Cnaan A, Laird NM, Slasor P. Using the general linear mixed model to analyse unbalanced 
repeated measures and longitudinal data. Stat Med 1997;16:2349–80. 
[EASL] European Association for the Study of the Live Clinical Practice Guidelines: 
management of cholestatic liver diseases. J Hepatol 2009;51:237–67. 
Efe C, Kahramanoglu-Aksoy E, Yilmaz B, et al. Pregnancy in women with primary biliary 
cirrhosis. Autoimmun Rev 2014;13:931–5. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
105 
Elman S, Hynan LS, Gabriel V, et al. The 5-D itch scale: A new measure of pruritus. Br J 
Dermatol 2010;162:587–93. 
[EMA] European Medicines Agency. Guidance on missing data in confirmatory clinical trials. 
2010https://www.ema.europa.eu/en/documents/scientific-guideline/guideline-missing-data-
confirmatory-clinical-trials_en.pdf  
FATIGUE: A brief guide to the PROMIS® Fatigue instruments. 2019;1–16. Available from: 
http://www.healthmeasures.net/images/PROMIS/manuals/PROMIS_Fatigue_Scoring_Manual.p
df 
[FDA] US Food and Drug Administration. FDA guidance on conduct of clinical trials of medical 
products during COVID-19 public health emergency: guidance for industry, investigators, and 
institutional review boards. Updated July 2, 2020. Available at 
https://www.fda.gov/media/136238/download. 
[FDA] US Food and Drug Administration. Multiple endpoints in clinical trials. Guidance for 
Industry. Draft Guidance. January 2017. 
Ge M, Durham LK, Meyer RD, et al. Covariate-adjusted difference in proportions from clinical 
trials using logistic regression and weighted risk differences. Drug Inf J 2011;45:481–93. 
Geenes V, Williamson C. Intrahepatic cholestasis of pregnancy. World J Gastroenterol 
2009;15:2049–66. 
Geenes V, Chappell LC, Seed PT, et al. Association of severe intrahepatic cholestasis of 
pregnancy with adverse pregnancy outcomes: a prospective population-based case-control study. 
Hepatol 2014;59:1482–91. 
Geenes V, Chambers J, Khurana R, et al. Rifampicin in the treatment of severe intrahepatic 
cholestasis of pregnancy. Eur J Obstet Reprod Biol 2015;189:59–63. 
Glantz A, Marschall HU, Mattsson LA. Intrahepatic cholestasis of pregnancy: relationships 
between bile acid levels and fetal complication rates. Hepatol 2004;40:467–74. 
Gonzales E, Stormon M, Sokal E, et al. Durability of treatment effect with long-term maralixibat 
in children with Alagille syndrome: 4-year safety and efficacy (Iconic Study). 2019a AASLD 
presentation.   
Gonzales E, Sturm E, Stormon M, et al. Phase 2 open-label study with a placebo-controlled drug 
withdrawal period of the apical sodium-dependent bile acid transporter inhibitor maralixibat in 
children with Alagille Syndrome: 48-week interim efficacy analysis. J Hepatol 
2019b;70:e119-20. 
Goulis DG, Walker IA, de Swiet M, et al. Preeclampsia with abnormal liver function tests is 
associated with cholestasis in a subgroup of cases. Hypertens Pregnancy 2004;23:19–27. 
Gurung V, Stokes M, Middleton P, et al. Interventions for treating cholestasis in pregnancy. 
Cochrane Database Syst Rev 2013;2013:CD000493. 
Hegade VS, Kendrick SF, Dobbins RL, et al. Effect of ileal bile acid transporter inhibitor 
GSK2330672 on pruritus in primary biliary cholangitis: a double-blind, randomised, 
placebo-controlled, crossover, phase 2a study. Lancet 2017;389:1114–23. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
106 
Herdman M, Gudex C, Lloyd A, et al. Development and preliminary testing of the new five-level 
version of EQ-5D (EQ-5D-5L). Qual Life Res 2011;20:1727–36. 
Kawaguchi A, Koch GG. Sanon: an R package for stratified analysis with nonparametric 
covariable adjustment. J Stat Softw 2015;671–37. 
Kremer AE, van Dijk R, Leckie P, et al. Serum autotaxin is increased in pruritus of cholestasis, 
but not of other origin and responds to therapeutic interventions. Hepatol 2012;56:1391–400. 
Larson AM. Drug-induced liver injury. UpToDate 2020 
Lee RH, Greenberg M, Metz TD, et al. Society for Maternal-Fetal Medicine consult series #53: 
Intrahepatic cholestasis of pregnancy: replaces consult #13, April 2011. Am J Obstet Gynecol 
2021;224:B2–9. 
Little R, Rubin D. Statistical analysis with missing data. New York: John Wiley. 1987. 
Little R, Yau L. Intent-to-treat analysis for longitudinal studies with drop-outs, Biometrics 
1996;52:1324–33. 
Lundasen T, Galman C, Angelin B et al. Circulating intestinal fibroblast growth factor 19 has a 
pronounced diurnal variation and modulates hepatic bile acid synthesis n man. J Intern Med 
2006;260:530–6. 
MacKay DF, Smith GCS, Debbie R, et al. Gestational age at delivery and special educational 
need: retrospective cohort study of 407,503 schoolchildren. PLoS Med 2010;7:e100289. 
Mallinckrodt CH, Clark WS, David SR. Accounting for dropout bias using mixed-effects 
models. J Biopharm Stat 2001;11:9–21. 
Mallinckrodt CH, Lane PW, Schnell D, et al. Recommendations for the Primary Analysis of 
Continuous Endpoints in Longitudinal Clinical Trials. Drug Inf J 2008;42:303–19. 
Mallinckrodt CH, Roger J, Chuang-Stein C, et al. Recent developments in the prevention and 
treatment of missing data. Drug Inf J 2013;48:68–80. 
Martin ML, Stassek L, Blum SI, et al. Development and adaptation of patient-reported outcome 
measures for patients who experience itch associated with primary biliary cholangitis. J Patient 
Rep Outcomes 2019;3:2. 
Martineau M, Raker C, Powrie R, et al. Intrahepatic cholestasis of pregnancy is associated with 
an increased risk of gestational diabetes. Eur J Obstet Gynecol Reprod Biol 2014;176:80–5. 
Martineau MG, Raker C, Dixon PH, et al. The metabolic profile of intrahepatic cholestasis of 
pregnancy is associated with impaired glucose tolerance, dyslipidemia, and increased fetal 
growth. Diabetes Care 2015;38:243–8. 
Mayo MJ, Pockros PJ, Jones D, et al. A randomized, controlled, Phase 2 study of maralixibat in 
the treatment of itching associated with primary biliary cholangitis. Hepatol Commun 
2019;3:365–81. 
Mohan M, Antonios A, Konje J, et al. Stillbirth and associated perinatal outcomes in obstetric 
cholestasis: a systematic review and meta-analysis of observational studies. Eur J Obstet 
Gynecol Reprod Biol 2019;3:100026. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
107 
Monte M, Rodriguez-Bravo T, Macias R, et al. Relationship between bile acid transplacental 
gradients and transport across the fetal-facing plasma membrane of the human trophoblast. 
Pediatr Res 1995;38:156–63. 
Molenberghs G, Kenward MG. Missing data in clinical studies. New York: Wiley. 2007. 
Molenberghs G, Thijs H, Jansen I, et al. Analyzing incomplete longitudinal clinical trial data. 
Biostatistics 2004;5:445–64. 
Moster D, Lie RT, Markestad T. Long-term medical and social consequences of preterm birth. N 
Engl J Med 2008;359:262–73. 
Nunez DJ, Yao X, Lin J, et al. Glucose and lipid effects of the ileal apical sodium-dependent bile 
acid transporter inhibitor GSK23330672: double-blind randomized trials with type 2 diabetes 
subects taking metformin. Diabetes Obes Metab 2016;18:654–62. 
Oppe M, Devlin NJ, van Hout B, et al. A program of methodological research to arrive at the 
new international EQ-5D-5L valuation protocol. Value Heal 2014;17:445–53. 
Oruc AS, Seckin B, Ozcan N, et al. Role of postprandial bile acids in prediction of perinatal 
outcome in intrahepatic cholestasis of pregnancy. J Obstet Gynaecol Res 2014;40:1883–9. 
Ovadia C, Sajous J, Seed PT, et al. Ursodeoxycholic acid in intrahepatic cholestasis of 
pregnancy: a systemic review and individual participant data meta-analysis. Lancet 
2021;6:547-58. 
Ovadia C, Seed PT, Sklavounos A, et al. Association of adverse perinatal outcomes of 
intrahepatic cholestasis of pregnancy with biochemical markers: results of aggregate and 
individual patient data meta-analyses. Lancet 2019;393:899–909. 
Ozkan S, Ceylan Y, Ozkan OV, et al. Review of a challenging clinical issue: intrahepatic 
cholestasis of pregnancy. World J Gastroenterol 2015;21:7134–41. 
Palmer M, Regev A, Lindor K, et al. Consensus guidelines: best practices for detection, 
assessment and management of suspected acute drug induced liver injury occurring during 
clinical trials in adults with chronic cholestatic liver disease. Aliment Pharmacol Ther 
2020;51:90–109. 
Patel D, Liu C, Falahati V, et al. Pregnancy experiences in women with primary sclerosing 
cholangitis. AASLD 2019. 
Pathak B, Sheibani L, Lee RH. Cholestasis of pregnancy. Obstet Gynecol Clin North Am 
2010;37:269–82. 
Pocock SJ, Simon R. Sequential treatment assignment with balancing for prognostic factors in 
the controlled clinical trial. Biometrics 1975;31:103–15. 
Quigley MA, Poulsen G, Boyle E, et al. Early term and late preterm birth are associated with 
poorer school performance at age 5 years: a cohort study. Arch Dis Child Fetal Neonatal Ed 
2012;97:F167–73. 
[RCOG] Royal College of Obstetricians & Gynaecologists. Guidance for maternal medicine 
services in the coronavirus (COVID-19) pandemic. Version 2.5, 9 December 2020; available at: 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
108 
https://www.rcog.org.uk/globalassets/documents/guidelines/2020-12-09-guidance-for-maternal-
medicine-services-in-the-coronavirus-covid-19-pandemic.pdf. 
RCOG Obstetric cholestasis. Green-top guideline no. 43. April 2011. 
Ratitch B, O'Kelly M. Implementation of pattern-mixture models using standard SAS/STAT 
procedures. Proceedings of PharmaSUG 2011 (Pharmaceutical Industry SAS Users Group), 
SP04, Nashville.  
Ratitch B, O’Kelly M, Tosiello R. Missing data in clinical trials: from clinical assumptions to 
statistical analysis using pattern mixture models. Pharm Stat 2013;12:337–47. 
Saigal S, Doyle LW. An overview of mortality and sequelae of preterm birth from infancy to 
adulthood. Lancet 2008;371:261–9. 
Schafer JL. Analysis of Incomplete Multivariate Data. New York: Chapman & Hall. 1997.  
Sepulveda WH, Gonzalez C, Cruz MA, et al. Vasoconstrictive effect of bile acids on isolated 
human placental chorionic veins. Eur J Obstet Gynecol Reprod Biol 1991;42:211–5. 
Shaw D, Frohlich J, Wittmann BA, et al. A prospective study of 18 patients with cholestasis of 
pregnancy. Am J Obstet Gynecol 1982;142:621–5. 
Shen Y, Zhou J, Zhang S, et al. Is it necessary to perform the pharmacological interventions for 
intrahepatic cholestasis of pregnancy? A Bayesian network meta-analysis. Clin Drug Investig 
2019;39:15–26. 
Siddiqui O, Hung HM, O'Neill R. MMRM vs. LOCF: a comprehensive comparison based on 
simulation study and 25 NDA datasets. J Biopharm Stat 2009;19:227–46. 
Stokes ME, Davis CS, Koch GG. Categorical data analysis using SAS. SAS Institute 
2012 Jul 31. 
Thompson R, Jaecklin T, Peetz C et al. Genotype and dose-dependent response to maralixibat in 
patients with bile salt export pump deficiency. 2019 AASLD presentation.   
Tran TT, Ahn J, Reau N. ACG clinical guideline: Liver disease and pregnancy. Am J 
Gastroenterol 2016;111:176–94. 
Verbeke G, Molenberghs G. Linear Mixed Models for Longitudinal Data. New York: Springer. 
2000. 
Walker K, Chappell LC, Hague WM et al. Pharmacological interventions for treating 
intrahepatic cholestasis of pregnancy. Cochrane Database Syst Rev 2020;7:CD000493. 
Williamson C, Gorelik J, Eaton BM, et al. The bile acid taurocholate impairs rat cardiomyocyte 
function: a proposed mechanism for intra-uterine fetal death in obstetric cholestasis. Clin Sci 
(Lond) 2001;100:363–9. 
Williamson C, Geenes V. Intrahepatic cholestasis of pregnancy. Obstet Gynecol 
2014;124:120-33. 
Wood AM, Livingston EG, Hughes BL, et al. Intrahepatic cholestasis of pregnancy: a review of 
diagnosis and management. Obstet Gynecol Surv 2018;73:103–9. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
109 
Yu L, Buysse DJ, Germain A, et al. Development of short forms from the PROMIS™ sleep 
disturbance and sleep-related impairment item banks. Behav Sleep Med 2012;10:6–24. 
Zinc RC, Koch GG. NParCov3: a SAS/IML macro for nonparametric randomization-based 
analysis of covariance. J Stat Sotw 2012;50:1–7. 
Zuo P, Dobbins RL, O’Connor-Semmes RL, et al. A systems model for ursodeoxycholic acid 
metabolism in healthy and patients with primary biliary cirrhosis. CPT Pharmacometrics Syst 
Pharmacol 2016;5:418–26. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
110 
Appendix 1 
Clinical Laboratory Tests 
The laboratory tests detailed below will be performed at the times indicated in the schedule of 
activities (Table 1).  Protocol-specific requirements for inclusion or exclusion of participants are 
detailed in protocol Section 5.  Additional tests may be performed at any time during the study as 
determined necessary by the investigator or required by local regulations.   
This list reflects the required laboratory assessments as of the effective date of this protocol; 
however, investigators should refer to the most current version of the study laboratory manual 
for full details of required laboratory assessments. 
Investigators must document their review of each laboratory safety report. 
Protocol-required serum or plasma clinical laboratory tests include the following:   
• Serology (screening only):  HIV, hepatitis B surface antigen, hepatitis C virus 
antibodies 
• Hematology:  Hemoglobin, neutrophils (absolute), hematocrit, eosinophils (absolute), 
RBC count, monocytes (absolute), platelets, basophils (absolute), WBC count (total 
and differential), lymphocytes (absolute) 
• Serum chemistry:  Sodium, phosphorus, potassium, protein, glucose, bicarbonate or 
carbon dioxide, BUN, albumin, creatinine, AST, calcium, ALT, chloride, GGT, 
thyrotropin (TSH), ALP, total bilirubin 
• Coagulation panel:  PT/INR, APTT 
• Fat-soluble vitamins:  Vitamin A (serum retinol), vitamin E (serum α-tocopherol), 
and vitamin D (serum 25-hydroxycholecalciferol) 
• Biomarkers:  Glycated albumin, lipid panel, total cholesterol, HDL cholesterol, LDL 
cholesterol, triglycerides, VLDL cholesterol, 7αC4, GLP-1, autotaxin, FGF-19, 
progesterone sulfate. 
• Umbilical cord blood (when possible):  Arterial blood gas (including pH), volixibat 
concentration (i.e., PK sample), serum bile acids, total cholesterol, low-density 
lipoprotein cholesterol, glucose 
Protocol-required urine laboratory tests include: 
• Urine screen for alcohol and drugs of abuse:  Amphetamines, cocaine, barbiturates, 
methadone, benzodiazepines, opiate metabolite, cannabinoids, phencyclidine, ethanol 
• Urinalysis analytes (by dipstick; minimum, the microscopic examination will consist 
of RBCs, WBCs, casts, and bacteria):  pH, bilirubin, glucose, nitrites, protein, 
leukocyte esterase, blood, specific gravity, ketones 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
111 
Appendix 2 
Genetics 
Use/Analysis of DNA 
Genetic variation may impact a participant’s response to therapy and susceptibility to, severity 
of, and progression of disease.  Variable response to therapy may be because of genetic 
determinants that impact drug absorption, distribution, metabolism, and excretion; mechanism of 
action of the drug; disease etiology; and/or molecular subtype of the disease being treated.  
Therefore, where local regulations and institutional review board/institutional ethics committee 
allow, a blood sample will be collected for DNA analysis from consenting participants. 
DNA samples will be used for research related to volixibat or intrahepatic cholestasis of 
pregnancy (ICP) and related diseases.  They may also be used to develop tests/assays, including 
diagnostic tests related to volixibat and ICP.  Genetic research may consist of the analysis of one 
or more candidate genes or the analysis of genetic markers throughout the genome (as 
appropriate). 
The samples may be analyzed as part of a multi-study assessment of genetic factors involved in 
the response to volixibat or study drugs of this class to understand study disease or related 
conditions. 
The results of genetic analyses may be reported in the clinical study report or in a separate study 
summary. 
The sponsor will store the DNA samples in a secure storage space with adequate measures to 
protect confidentiality. 
The samples will be retained while research on volixibat continues but no longer than 10 years or 
other period as per local requirements. 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
112 
Appendix 3 
Liver Safety:  Suggested Actions and Follow-Up Assessments 
The following algorithms should be used to assess for potential drug-induced liver injury 
event(s).  In the event there is any ambiguity about recommended actions according to the 
following algorithms, or if there is a scenario that is not covered by the existing algorithms, the 
study medical monitor should be consulted to determine the appropriate study action. 
For Participants with Normal Baseline ALT, AST, and Total Bilirubin 
Baseline 
ALT during Treatment 
with Study Drug 
Other Concurrent Parameters 
Observed during ALT or AST 
Elevation 
Study Actiona 
ALT, AST, and 
total bilirubin 
≤ ULN 
— 
Any hepatic decompensation 
event 
Interrupt study drug and 
inform study medical 
monitor ASAP; 
permanent 
discontinuation of study 
drug upon confirmation 
of diagnosis 
ALT >8 × ULN 
— 
Interrupt study drug 
and discuss as soon as 
possible with medical 
monitor; consider 
permanent 
discontinuation of 
study drug. 
ALT >5 × ULN for more 
than 2 weeks 
— 
ALT >3 × ULN 
and one of the following:  
total bilirubin >2 × ULN or 
INR >1.5 
Interrupt study drug 
and implement close 
observation 
ALT >3 × ULN 
and clinical symptomsb 
ALT >3 × ULN 
— 
Repeat testing within  
2–3 days. 
If results not improved, 
implement close 
observation 
ASAP=as soon as possible; INR=international normalized ratio; ULN=upper limit of normal. 
a Time frames mentioned under “Study Action” (e.g., ASAP, within 2–3 days) shall be based on date of 
awareness of laboratory results or events driving the study action. 
b Clinical symptoms include fatigue, nausea, vomiting, right upper quadrant pain or tenderness, fever, rash, 
and/or eosinophilia (>5%) not otherwise explained by underlying disease or alternative etiology. 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
113 
For Participants with Abnormal Baseline ALT, AST, or Total Bilirubin 
Baseline 
ALT during Treatment 
with Study Drug 
Other Concurrent 
Parameters Observed 
during Treatment with 
Study Drug 
Study Actiona 
Any ALT, AST, or total 
bilirubin > ULN 
— 
Any hepatic 
decompensation event 
Interrupt study drug 
and inform medical 
monitor ASAP; 
permanent 
discontinuation of 
study drug upon 
confirmation of 
diagnosis. 
— 
Total bilirubin ≥2 × BLMb 
Interrupt study drug 
and implement close 
observation 
ALT or AST > ULN to 
<2 × ULN 
ALT >5 × BLM or reaches 
300 U/L (whichever is 
lower) 
— 
Interrupt study drug 
and implement close 
observation 
ALT >2 × BLM 
and any of the following:  
total bilirubin ≥2 × BLMb, 
INR increase by 0.2b, or 
clinical symptomsc 
ALT >2 × BLM 
or total bilirubin between 
>1.5 and <2 × BLMb 
Repeat testing within 
2–3 days. 
If results not improved, 
implement close 
observation 
ALT or AST ≥2 x ULN  
ALT >2 × BLM or reaches 
300 U/L (whichever is 
lower) 
or total bilirubin between 
>1.5 × and <2 × BLMb 
Repeat testing within 
2–3 days.   
If results do not 
improve, implement 
close observation. 
ALT >2 × BLM or reaches 
300 U/L (whichever is 
lower) 
and any of the following:  
total bilirubin ≥ 2 × BLMb, 
INR increase by 0.2b, or 
clinical symptomsc  
Interrupt study drug 
and implement close 
observation 
ALT >3 × BLM or reaches 
400 U/L (whichever is 
lower) 
— 
BLM=baseline measurement; INR=international normalized ratio; ULN=upper limit of normal. 
Note:  See section below for more details on study action.  
a Time frames mentioned under “Study Action” (e.g., ASAP, within 2-3 days) shall be based on date of 
awareness of laboratory results or events driving the study action. 
b 
Please follow the recommended Study Action if the current total bilirubin or INR value is > ULN.  If the current 
total bilirubin or INR value is ≤ ULN, clinical judgment should be exercised prior to implementing the 
recommended Study Action. 
c 
Clinical symptoms include fatigue, nausea, vomiting, right upper quadrant pain or tenderness, fever, rash, and/or 
eosinophilia (>5%) not otherwise explained by underlying disease or alternative etiology. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
114 
Study Actions 
Stop study drug: 
• Stop study drug immediately, closely observe the participant (see below), and follow 
until resolution of symptoms or signs. 
Interrupt study drug: 
• Stop study drug immediately and repeat ALT, AST, total bilirubin, and/or INR within 
3 days and closely observe the participant (see below).  
• Study drug can be restarted if liver test results return to baseline levels or if an 
alternate cause for the transaminase elevations is found and addressed based on the 
judgment of the investigator (Palmer et al. 2020).  Rechallenges should be undertaken 
only with medical monitor approval. 
Close observation: 
• Repeat liver enzyme and serum bilirubin tests 2 to 3 times weekly.  Frequency of 
repeat testing can be decreased to once a week or less if abnormalities stabilize or the 
study drug has been discontinued and the participant is asymptomatic. 
• Obtain a detailed history of symptoms and prior or concurrent diseases. 
• Obtain a history of concomitant drug use (including nonprescription medications and 
herbal/dietary supplement preparations), alcohol use, recreational drug use, and 
special diets. 
• Rule out acute viral hepatitis types A, B, C, D, and E; autoimmune or alcoholic 
hepatitis; nonalcoholic steatohepatitis; hypoxic/ischemic hepatopathy; and biliary 
tract disease (except ICP). 
• Obtain a history of exposure to environmental chemical agents. 
• Obtain additional tests to evaluate liver function as appropriate (e.g., INR, direct 
bilirubin). 
• 
Consider gastroenterology or hepatology consultations.  
•  
Definition of hepatic decompensation event—presence of any of the following 
(Palmer et al. 2020): 
• Bleeding esophageal varices 
• Portal hypertension 
• Hepatic encephalopathy 
• 
Ascites  


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
115 
Appendix 4 
Adult Itch Reported Outcome 
The Adult Itch Reported Outcome (ItchRO) instrument will be completed using an electronic 
diary (eDiary).  The eDiary will be completed once daily using a 24-hour recall period.  Each 
score will have a range from 0 to 10, with higher scores indicating increasing itch severity.  
A sample screen shot for the eDiary Adult ItchRO assessment tool is shown in the figure below: 
 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
116 
Appendix 5 
5-D Itch 
The 5-D itch scale was developed for the multidimensional quantification of pruritus that is 
sensitive to change over time (Elman et al. 2010).  The instrument includes domains for duration, 
degree, direction, disability, and distribution of pruritus.  The scores of scores of each of the 
5 domains are achieved separately and then summed together to obtain a total 5-D score.  The 
5-D scores can potentially range between 5 (no pruritus) and 25 (most severe pruritus). 
Single-item domain scores (duration, degree, and direction) are equal to the value indicated 
below the response choice (range, 1–5). 
The disability domain includes 4 items that assess the impact of itching on daily activities:  sleep, 
leisure/social activities, housework/errands, and work/school.  The score for the disability 
domain is achieved by taking the highest score on any of the 4 items. 
For the distribution domain, the number of affected body parts is tallied (potential sum 0–16), 
and the sum is sorted into 5 scoring bins. 
The 5-D Itch scale for this study will use a 1-week recall period.  The 5-D Itch scale may be used 
to construct a total itch score.  Domains 1 through 3 contain only a single-item and require no 
special scoring to define the domain score.  The disability domain is composed of 4 items and is 
defined as the highest rating observed across the 4 disability items.  This produces a disability 
domain score ranging from 1 to 5.  The distribution domain is composed of 16 binary 
(present/absent) items; these items are summed to create a score defining the count of body areas 
affected, ranging from 0 to 16.  The distribution domain score is then categorized as follows: 
5-D Itch Scoring Bins 
Distribution Domain Sum 
(0–16) 
Assigned Score 
0–2 
1 
3–5 
2 
6–10 
3 
11–13 
4 
14–16 
5 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
117 
5-D Pruritus Scale 
 
. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
118 
Appendix 6 
Clinical Scratch Scale 
 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
119 
Appendix 7 
PROMIS® Fatigue and Sleep Modules 
The PROMIS® SF v1.0-Fatigue 7a is the original 7-item short form of the PROMIS® Fatigue 
measure.  It was designed for oncology patients to assess the impact and experience of fatigue 
from mild subjective feelings of tiredness to sustained sense of exhaustion that decreases one’s 
ability to execute daily activities and function normally in family or social roles.  The recall 
period for the measure is 7 days.  Respondents endorse each item using a 5-point response scale:  
Never, Rarely, Sometimes, Often, and Always.  A single item, “How often did you have enough 
energy to exercise strenuously?,” is reverse scored.  Developers of the measure provide several 
ways to score the items, including model-based scores, sum scores, or T scores.  The analyses 
that follow will utilize the T score. 
 
PROMIS Fatigue – Short Form 7a 
 
Source:  31 July 2018 © 2008-2018 PROMIS Health Organization (PHO) 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
120 
The PROMIS® SF v1.0-Sleep Disturbance in an 8-item measure that assesses quality of sleep, 
sleep depth, and restoration associated with sleep.  All items use a recall period of 7 days.  This 
measure targets no specific sleep disorders and is a general measure of sleep disturbance.  All 
items use a 5-point response scale, the specific response options vary by items.  The first 4 items 
use response options that range from Not at all to Very much.  The next 3 items use response 
options that range from Never to Always.  The final item assesses sleep quality ranging from 
Very poor to Very good.  A mix of items are reverse coded.  After correcting for reverse coding, 
model-based scores, sum scores, or T scores are available.  These T scores will be used for the 
analyses.  
PROMIS Sleep Disturbance – Short Form 8b  
 
Source:  3 May 2016 © 2008-2016 PROMIS Health Organization and PROMIS Cooperative Group 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
121 
Appendix 8 
Patient Impression of Severity-Itch 
The Patient Impression of Severity-Itch (PIS-Itch) was designed to assess severity of itching.  
The PIS-Itch will be completed by participants at time points as specified in the schedule of 
activities (Table 1).  The questionnaire was designed for self-administration and uses a 4-point 
scale from No itch to Severe.  The PIS-Itch scores will be used as anchors to help assess 
meaningful change for the Adult Itch Reported Outcome (ItchRO) in the study  
 
How would you rate the severity of your worst itch in the past 7 days? 
 
 No itch 
 Mild 
 Moderate 
 Severe 
 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
122 
Appendix 9 
Patient Global Impression of Change-Itch 
The Patient Global Impression of Change-Itch (PGIC-Itch) was designed to assess change in 
itching from baseline after being treated with study drug.  The PGIC-Itch will be completed by 
participants at specified time points in the schedule of activities (Table 1).   
The questionnaire was designed for self-administration and uses a 7-point scale from Much 
better to Much worse.  The PGIC-Itch scores will be used as anchors to help assess meaningful 
change for the Adult Itch Reported Outcome (ItchRO) in the study. 
How would you rate the change in your worst itch since the start of the study? 
 
 Much better (1) 
 Better (2) 
 A little better (3) 
 No change (4) 
 A little worse (5) 
 Worse (6) 
 Much worse (7) 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
123 
Appendix 10 
List of Known OATP2B1 Substrates 
The following drugs are known to be OATP2B1 substrates: 
• Bosentan 
• Bromsulphthalein 
• Dehydroepiandrosterone 
• Estrone-3-sulfate 
• Fexofenadine 
• Glyburide 
• Quercetin 
• Scutellarin (herbal) 
• Statins 
Atorvastatin 
Fluvastatin 
Pitavastatin 
Pravastatin 
Rosuvastatin 
• Sulfasalazine 
• Telmisartan 
• SN-38 carboxylate (topoisomerase inhibitor metabolite) 
• SN-38 lactone (topoisomerase inhibitor metabolite) 
 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
124 
Appendix 11 
Management of Clinical Study Procedures and Participants 
during COVID-19 Pandemic or Other Force Majeure 
This appendix provides guidance for participant safety and ongoing access to medical care and 
investigational product during the global novel coronavirus 2019-nCoV (COVID-19) pandemic.  
During this global public health crisis, pragmatic and harmonized actions are required to ensure 
the necessary flexibility and procedural simplifications that are needed to maintain the integrity 
of the clinical studies and to ensure the rights, safety, and wellbeing of study participants and the 
safety of clinical study staff. 
The measures detailed here are implemented across Mirum studies on a temporary basis until the 
pandemic is considered resolved by governmental and public health organizations, as applicable. 
Regardless of the guidance provided below, consideration should be given to public health 
advice at the study locations and individual benefit/risk in treatment decisions for participants at 
the study site during the pandemic (EMA 2020; FDA 2020).  Logistical requirements should also 
be considered, such as the ability of participants to travel to the study site, accessibility of public 
transportation, site restrictions on clinical studies, etc. 
The safety of the study participants is of primary importance, and risks of involvement in the 
study, in particular with added challenges due to COVID-19, will be weighed against anticipated 
benefit for the study participants and society. 
Study Participation 
Study sites may continue to recruit new participants, if deemed appropriate on benefit-risk 
assessment as described and provided that ALL of the following activities to preserve study 
integrity can be met: 
• Upon discussion with the site monitor, the study site has confirmed the ability to 
enroll and manage studies and participants effectively and in compliance with the 
protocol and this appendix. 
• Upon discussion with the sponsor or designee, the study site has confirmed that 
appropriate safety monitoring can take place, in compliance with the protocol and this 
appendix. 
• Data will continue to be entered into the electronic case report form (eCRF) and 
queries resolved in a timely manner. 
• The site monitor is able to access the study site to perform onsite monitoring or is 
able to perform remote monitoring of data. 
Conduct of Telephone/Virtual or Alternative Visits 
Due to the current pandemic, it is conceivable that not all participants visit commitments can be 
fulfilled.  If a participant or caregiver is unable or unwilling to attend a study visit or a study site 
is unable to permit onsite visits by participants and caregivers, adaptation of the onsite visit to a 
telephone visit, virtual visit, or use of an alternative location for assessment (including but not 
limited to local laboratories, family physician, home visit) is recommended to ensure continuity 
of participant care during the study (as an interim measure).  Priority should be given to 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
125 
maintaining ongoing safety follow-up.  Study sites should speak with their site monitor before 
performing a telephone or virtual visit so he or she may provide guidance regarding logistics that 
may need consideration.  Study sites should contact the medical monitor if the participant must 
miss >1 onsite visit in succession, because multiple incomplete visits may have the potential to 
impact evaluation of study endpoints as well the participant’s safety.   
The decision to accept protocol deviations for missed assessments is based on the risk to the 
participant of discontinuing study participation versus missed assessments, such as safety 
laboratory assessments.  Where possible, a home care visit should be organized to avoid missing 
visits or assessments. 
Alternative Blood Sample Collection 
Where possible and permitted, homecare can be organized through qualified health care 
professionals, trained on the study protocol, to collect samples at the participant’s home (or other 
agreed upon location).  It is preferred that this alternative blood sample collection is performed in 
a manner to support delivery of samples to the central laboratory, but the analysis of samples 
may be performed at local laboratories, if necessary.  If the analyses are performed at the local 
laboratories, the site will follow up with the participant to obtain the results and local laboratory 
reference ranges for data entry into EDC as soon as they are available. 
Safety Reporting and Volixibat Treatment Recommendations for COVID-19 
The sponsor recognizes that COVID-19 presents an increased risk for all participants.  Due to the 
potential impact of COVID-19 on multiple organ systems, the sponsor recommends the 
following dose modification and management plan for participants with confirmed or suspected 
COVID-19 while receiving treatment with volixibat.  
The following safety reporting guidelines are required:  
• All confirmed or suspected COVID-19–related adverse events (AEs) must be 
recorded in the eCRF and the Serious Adverse Event (SAE) Report Form if the event 
meets the seriousness criteria.  SAEs are reportable to the sponsor immediately 
without undue delay after becoming aware of the event and no later than 24 hours of 
awareness.  All study-drug interruptions or modifications must be recorded on the AE 
and drug administration eCRFs. 
• If an event is suspected to be COVID-19 infection, continuation of study drug, and 
any dose modifications should be assessed on a case-by-case basis, depending on the 
participant’s health status, and discussed with the medical monitor if needed.  The 
COVID-19 infection should be managed as per local treatment guidance and 
investigator’s clinical judgment. 
Drug-Drug Interaction Guidance Regarding Medication Used to Treat COVID-19 
• The study protocol and Investigator Brochure should be referenced for drug-drug 
interaction information.  For further information the medical monitor can be 
contacted. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
126 
Guidance Regarding Vaccination against COVID-19 
• Participants should be requested to contact the site upon planned vaccination against 
COVID-19.  The vaccine should be entered in the eCRF as a concomitant medication 
and any new or worsened symptom or sign recorded as an adverse event and assessed 
for seriousness.  Volixibat is taken orally, is minimally absorbed with systemic levels 
below the lower limit of quantification, and binds with and inhibits the ileal bile acid 
transporter (IBAT) in the distal ileum.  The vaccine is administered and acts 
systemically; hence, no drug-drug interaction is expected, and no need for unblinding 
is foreseen.   
Documenting Alternative Contacts with Participants 
If an onsite visit is replaced by a telephone or virtual study visit, the following are guidelines for 
data capture: 
• If the visit is listed as onsite but is performed remotely, data should be captured as per 
a normal visit (i.e., document the remote visit in the source documents and complete 
the relevant eCRF pages to capture the visit date, and any possible assessment that 
can be obtained, such as AEs, study drug administration, and/or concomitant 
medications and any additional safety or efficacy information).  All assessments that 
cannot be performed should be marked as not done in the eCRF.  Any protocol 
deviations related to COVID-19 should be recorded in the clinic notes, prefixed 
COVID-19.   
• Visits that require procedures that cannot be performed remotely should be discussed 
with the site monitor because this may impact efficacy or safety analyses and should 
be documented as a protocol deviation due to COVID-19. 
Site-to-Participant Drug Shipment Instructions during Pandemic Containment 
If a participant is unable to go to the study site because of pandemic containment, the study site 
may ship the study drug to the home of the participant (or other agreed location) following 
approval by the sponsor.  
For such shipment, the following conditions must be met: 
• The sponsor is responsible for delivery of the study drug to the study site.  
Organization of shipments from the site to the participant will be the responsibility of 
the study site. 
• The participant or caregiver is informed about the shipment method, confirms the 
address for receipt of the drug, and agrees that his or her personal information (i.e., 
contact information) may be given to a professional carrier. 
• The investigator or designee (e.g., pharmacy) securely packages the drug for 
shipment.  
• A professional carrier is used by the investigator or designee to ship the drug securely 
and maintain chain of custody, with evidence provided.  Volixibat should be stored 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
127 
and shipped as directed in the Pharmacy Manual.  Shipments that are expected to be 
completed within 48 hours from pickup to delivery do not generally require any 
specific temperature monitoring. 
• To respect participant confidentiality, the carrier should be given only the contact 
information of the recipient.  The sponsor should not receive any personal 
information about the participant. 
• A procedure is defined with the carrier to immediately upon delivery confirm the 
receipt of the drug by the recipient and that it is received in good condition. 
• The site contacts the recipient to confirm the receipt of the drug and to confirm it is 
delivered in the expected conditions (e.g., not leaking, not broken) and gives 
instructions about the drug administration and storage.  If the drug is delivered and is 
not within the expected conditions, the site will give instructions to the participant 
about the next steps. 
• The investigator or designee completes the drug accountability forms with each 
shipment made directly to a participant. 
• All documentation (originals/copies, as applicable) related to the site-to-participant 
drug shipment should be filed in the investigator site file, including the list of the 
medication being delivered, the quantity involved, and documentation of receipt by 
the study participant.  
• Participants should retain unused study drug and containers and return them to the 
investigator the next time they visit the investigator site  
COVID-19 Specific Remote Source Data Verification 
The source documents/source data considered for remote source data verification (rSDV) are 
those related to the primary endpoint, AEs/SAEs, important medical events, or the reasons for 
exclusion of a participant from the study. 
Remote access to source documents/source data for monitoring purposes may only take place in 
justified exceptional cases and only to the extent strictly necessary (i.e., only when direct access 
to study source data is not available due to COVID-19 pandemic restrictions).  
The following 3 options for source data reconciliation without the study monitor being 
physically present at the study site may be used, based on the site-specific source 
documentation/source data: 
• The study site will provide the study monitor, under the responsibility of the 
investigator, with copies of the source documents/source data in which personal 
identifying information of the study participants and information pertaining to their 
privacy has been obscured or redacted. 
• Under the responsibility of the investigator, the study site will grant the study monitor 
direct, controlled, remote access to the systems with which the source 
documents/source data are managed. 


Volixibat 
Mirum Pharmaceuticals, Inc. 
Protocol Number: VLX-401 
 
CONFIDENTIAL 
128 
• The study site will grant the study monitor, under the responsibility of the 
investigator, passive access to the source documents/source data via live image 
transmission (e.g., sharing of the screen or image/sound transmission). 
Depending on the option selected for rSDV, the full process to be followed and requirements 
needed to be met are described in the specific rSDV section of the clinical monitoring plan as 
well as in a corresponding guideline for the investigators. 
In the case of live image transmission, this will take place exclusively via secured 
systems/environments and systems/servers within European Economic Area/European Union. 
In all cases, rSDV will be conducted exclusively by the authorized persons in accordance with 
the written informed consent of the study participants and the written agreement of the Principal 
Investigator (PI)/PI’s institution. 
Remote source data verification will take place in a protected environment (i.e., providing 
protection from unauthorized access in any form, including the use of privacy screens to prevent 
unauthorized viewing of source documents/source data), the source documents/source data 
reviewed by the study monitor will not be permanently stored by the study monitor, and if 
necessary, temporarily saved files (including ones automatically generated by the system) are 
permanently deleted at short notice. 
The study monitor will securely destroy any copy of obscured/redacted documents, whether 
paper or electronic, as soon as they have been used for source data verification.  
Appropriate corrective measures will be implemented in the event of technical difficulties or if 
the security of the transmission is no longer guaranteed. 
The information and communication technology used by the sponsor and the study site for rSDV 
is designed in such a way that secure and General Data Protection Regulation–compliant 
transmission is guaranteed. 
 
REFERENCES 
United States Food and Drug Administration. FDA guidance on conduct of clinical trials of 
medical products during COVID-19 public health emergency. March 2020 (updated 
30 August 2021). Available online at https://www.fda.gov/regulatory-information/search-fda-
guidance-documents/fda-guidance-conduct-clinical-trials-medical-products-during-covid-19-
public-health-emergency. 
European Medicines Agency. Guidance on the management of clinical trials during the 
COVID-19 (coronavirus) pandemic. Version 3, 28 April 2020 (updated Version 4, 
4 February 2021). Available online at 
https://ec.europa.eu/health/sites/health/files/files/eudralex/vol-
10/guidanceclinicaltrials_covid19_en.pdf. 
 

SAP_001.pdf: 
VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 1 
 
 
 
STATISTICAL ANALYSIS PLAN 
 
 
 
Study Title: 
A Phase 2a/2b Randomized Double-Blind 
Placebo-Controlled Study to Evaluate the Efficacy and 
Safety of Volixibat in Adult Women with Intrahepatic 
Cholestasis of Pregnancy and Elevated Serum Bile Acid 
Concentrations (OHANA) 
 
 
Name of Test Drug: 
Volixibat  
 
 
Study Number: 
VLX-401 
 
 
Protocol Version (Date): 
Original Protocol, Version 1, 14 October 2020 
 
 
Analysis Type: 
Interim and Final Analyses  
 
 
Analysis Plan Version: 
1.0 
 
 
Analysis Plan Date: 
13 November 2020 
 
 
Analysis Plan Author(s): 
Will Garner, PhD 
 
 
 
CONFIDENTIAL AND PROPRIETARY INFORMATION 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 2 
 
TABLE OF CONTENTS 
LIST OF ABBREVIATIONS .................................................................................................................. 4 
1. 
INTRODUCTION ........................................................................................................................... 6 
1.1. 
Study Objectives ................................................................................................................. 6 
1.1.1. 
Primary Objective and Endpoint ....................................................................... 6 
1.1.2. 
Secondary Objectives and Endpoints ................................................................ 6 
1.1.3. 
Safety Objective and Endpoints ........................................................................ 7 
1.1.4. 
Exploratory Objectives and Endpoints .............................................................. 7 
1.2. 
Study Design ....................................................................................................................... 9 
1.3. 
Sample Size Determination ............................................................................................... 11 
2. 
TYPE OF PLANNED ANALYSIS ............................................................................................... 12 
2.1. 
Interim Analyses (Part 1) .................................................................................................. 12 
2.2. 
Supplemental Cohort Analysis .......................................................................................... 12 
2.3. 
Final Analysis (Part 2) ...................................................................................................... 12 
3. 
GENERAL CONSIDERATIONS FOR DATA ANALYSES ....................................................... 13 
3.1. 
Analysis Sets ..................................................................................................................... 13 
3.2. 
Participants Grouping ....................................................................................................... 14 
3.3. 
Strata and Covariates ........................................................................................................ 14 
3.4. 
Examination of Participant Subgroups .............................................................................. 15 
3.5. 
Multiple Comparisons ....................................................................................................... 15 
3.6. 
Missing Data and Outliers ................................................................................................. 15 
3.6.1. 
Missing Data ................................................................................................... 15 
3.6.2. 
Outliers ............................................................................................................ 16 
3.7. 
Data Handling Conventions and Transformations ............................................................ 16 
3.8. 
Analysis Visit Windows .................................................................................................... 16 
3.8.1. 
Definition of Study Day .................................................................................. 16 
3.8.2. 
Analysis Visit Windows .................................................................................. 17 
3.8.3. 
Selection of Data in the Event of Multiple Records in an Analysis Visit 
Window ........................................................................................................... 18 
4. 
PARTICIPANT DISPOSITION .................................................................................................... 20 
4.1. 
Participant Enrollment and Disposition ............................................................................ 20 
4.2. 
Extent of Study Drug Exposure and Adherence ............................................................... 21 
4.2.1. 
Duration of Exposure to Study Drug ............................................................... 21 
4.2.2. 
Adherence to Study Drug ................................................................................ 21 
4.3. 
Prior and Concomitant Medications .................................................................................. 22 
4.3.1. 
Prior Non-Antipruritic Medications ................................................................ 22 
4.3.2. 
Concomitant Medications ............................................................................... 23 
4.4. 
Protocol Deviations ........................................................................................................... 23 
5. 
BASELINE CHARACTERISTICS ............................................................................................... 24 
5.1. 
Demographics ................................................................................................................... 24 
5.2. 
Other Baseline Characteristics .......................................................................................... 24 
5.3. 
Medical History ................................................................................................................ 24 
5.4. 
Prior Antipruritic or Prior ICP Therapy ............................................................................ 25 
6. 
EFFICACY ANALYSES .............................................................................................................. 26 
6.1. 
Primary Efficacy Endpoint ................................................................................................ 26 
6.1.1. 
Definition of the Primary Efficacy Endpoint .................................................. 26 
6.1.2. 
Estimand and Analysis of the Treatment Effect .............................................. 26 
6.1.3. 
Intercurrent Events and Handling Strategies ................................................... 27 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 3 
6.1.4. 
Rationale for Primary Analysis Method .......................................................... 28 
6.1.5. 
Sensitivity Analysis of the Primary Efficacy Endpoint ................................... 29 
6.1.6. 
Missing Data ................................................................................................... 29 
6.1.7. 
Complete Multiple Imputation Differentiating Interrcurrent Events ............... 29 
6.1.8. 
Tipping Point Analysis .................................................................................... 31 
6.2. 
Secondary Efficacy Endpoints .......................................................................................... 32 
6.3. 
Exploratory Efficacy Endpoints ........................................................................................ 33 
7. 
SAFETY ANALYSES................................................................................................................... 36 
7.1. 
Adverse Events and Deaths ............................................................................................... 36 
7.1.1. 
Adverse Event Dictionary ............................................................................... 36 
7.1.2. 
Adverse Event Severity ................................................................................... 36 
7.1.3. 
Relationship of Adverse Events to Study Drug ............................................... 36 
7.1.4. 
Serious Adverse Events ................................................................................... 36 
7.1.5. 
Treatment-Emergent Adverse Events ............................................................. 36 
7.1.5.1. 
Definition of Treatment-Emergent Adverse Events .................. 36 
7.1.5.2. 
Incomplete Dates ....................................................................... 37 
7.1.6. 
Summaries of Adverse Events and Deaths ...................................................... 37 
7.1.6.1. 
Summaries of AE Incidence ...................................................... 37 
7.1.7. 
Additional Analysis of Adverse Events .......................................................... 39 
7.2. 
Laboratory Evaluations ..................................................................................................... 39 
7.2.1. 
Summaries of Numeric Laboratory Results .................................................... 39 
7.2.2. 
Shifts Relative to the Baseline Value .............................................................. 40 
7.3. 
Body Weight, Height, and Vital Signs .............................................................................. 40 
7.4. 
Electrocardiogram Results ................................................................................................ 40 
7.5. 
Other Safety Measures ...................................................................................................... 41 
7.5.1. 
Health Utilization Assessments ....................................................................... 41 
7.5.2. 
Newborn Safety Assessments ......................................................................... 41 
7.6. 
Changes From Protocol-Specified Safety Analyses .......................................................... 41 
8. 
PATIENT-REPORTED OUTCOMES .......................................................................................... 42 
9. 
PHARMACOKINETIC ANALYSES ........................................................................................... 43 
10. REFERENCES .............................................................................................................................. 44 
11. SOFTWARE .................................................................................................................................. 46 
12. SAP REVISION ............................................................................................................................ 47 
13. APPENDIX 1 SCHEDULE OF ACTIVITIES .............................................................................. 48 
14. APPENDIX 2 ADVERSE EVENTS OF SPECIAL INTEREST AND CLINICAL INTEREST . 53 
15. APPENDIX 3 SAS SAMPLE CODES .......................................................................................... 55 
 
LIST OF TABLES 
Table 1 
Analyses Sets..................................................................................................... 14 
Table 2 
Analysis Visit Windows for ItchRO^, sBA, Hematology*, Chemistry*, 
Coagulation*, Weight, Vital Signs, and Urinalysis ........................................... 17 
Table 3 
Analysis Visit Windows for 5-D Itch, CSS, EQ-5D-5L, PROMIS Fatigue and 
Sleep PROs, PIS-Itch, PGIC-Itch, and Biomarker Samples (C4, FGF-19, 
Autotaxin, Progesterone Sulfate, GLP-1) .......................................................... 18 
Table 4 
Analysis Visit Windows for Lipid Panel and Glycated Albumin ...................... 18 
Table 5 
Analysis Visit Windows for Vitamin A, D, and E Levels and Fetal Ultrasound
 ........................................................................................................................... 18 
Table 6 
Perinatal Outcome Severity Scoring ................................................................. 35 
Table 7  
Schedule of Activities ....................................................................................... 48 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 4 
 
LIST OF ABBREVIATIONS 
7αC4 
7α-hydroxy-cholesten-3-one 
AE 
adverse event 
AESI 
adverse event of special interest 
ALP 
alkaline phosphatase 
ALT 
alanine aminotransferase 
ANCOVA 
analysis of covariance 
AST 
aspartate aminotransferase 
ATC 
Anatomical Therapeutic Chemical 
AUC 
area under the plasma concentration-time curve 
BMI 
body mass index 
BPP 
biophysical profile 
CMH 
Cochran-Mantel-Haenszel 
CI 
confidence interval 
Cmax 
maximum observed concentration 
CSR 
clinical study report 
CSS 
clinician scratch scale 
CTCAE 
Common Terminology Criteria for Adverse Events 
CTG 
cardiotocography 
EAIR 
exposure-adjusted incidence rate 
ECG 
electrocardiogram 
eCRF 
electronic case report form 
ECI 
events of clinical interest 
eDiary 
electronic diary 
EQ-5D-5L 
EuroQoL 5-dimension, 5-level 
FGF-19 
fibroblast growth factor 19 
GLP-1 
glucagon-like peptide 1 
HLGT 
high-level group term 
HLT 
high-level term 
ICF 
informed consent form 
ICP 
intrahepatic cholestasis of pregnancy 
ID 
identification 
IDMC 
independent data monitoring committee 
INR 
international normalized ratio 
ItchRO 
Itch Reported Outcome 
ITT 
intent to treat 
IV 
intravenous 
IXRS 
interactive voice or web response system 
LLT 
lower-level term 
LMP 
last menstrual period 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 5 
LOQ 
limit of quantitation 
LR 
logistic regression 
LS 
least squares 
MAR 
missing at random 
MedDRA 
Medical Dictionary for Regulatory Activities 
MH 
Mantel-Haenszel 
MI 
multiple imputation 
mITT 
modified intent-to-treat 
MMRM 
mixed-effects model for repeated measures 
MNAR 
missing not at random 
NICU 
neonatal intensive care unit 
NST 
nonstress test 
PD 
pharmacodynamic 
PGIC-Itch 
Patient Global Impression of Change-Itch 
PIS-Itch 
Patient Impression of Severity-Itch 
PK 
pharmacokinetic 
PP 
per-protocol 
PPROM 
preterm premature rupture of the membranes 
PRO 
patient-reported outcome 
PROMIS 
Patient-Reported Outcomes Measurement Information System 
PT 
preferred term 
Q1, Q3 
first quartile, third quartile 
REML 
restricted maximum likelihood 
SAE 
serious adverse event 
SAP 
statistical analysis plan 
sBA 
serum bile acid 
SD 
standard deviation 
SF 
short form 
SOC 
system organ class 
TEAE 
treatment-emergent adverse event 
TFLs 
tables, figures, and listings 
Tmax 
time to reach Cmax 
TRAE 
treatment-related treatment-emergent adverse event 
ULN 
upper limit of normal 
VLX 
volixibat 
WHO 
World Health Organization 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 6 
1. 
INTRODUCTION 
This statistical analysis plan (SAP) describes the statistical analysis methods and data 
presentations to be used in tables, figures, and listings (TFLs) for the interim analysis as well 
as final analysis to support the clinical study report (CSR) for Study VLX-401.  This SAP is 
based on the study protocol Version 1, 14 October 2020, and the electronic case report forms 
(eCRF). The SAP will be finalized before the interim analysis.  
Any deviations from the approved protocol will be documented in either Section 6 (efficacy) 
and/or Section 7 (safety). 
1.1. 
Study Objectives 
The following objectives and endpoints will be evaluated in participants who meet study 
eligibility criteria.  Unless otherwise specified, these apply to participants in the primary 
cohort. 
1.1.1. 
Primary Objective and Endpoint 
• To assess the efficacy of volixibat (VLX) on the reduction of elevated sBA 
concentrations in participants with intrahepatic cholestasis of pregnancy (ICP) on the 
basis of the following endpoint: 
o Mean change from baseline to Week 3 of the study treatment period in total 
serum bile acid (sBA) concentration 
1.1.2. 
Secondary Objectives and Endpoints 
• To assess the efficacy of VLX on pruritus due to ICP on the basis of the following 
endpoint: 
o Mean change from baseline to Week 3 of the study treatment period in the 
weekly average worst daily itch score as measured by the Adult Itch Reported 
Outcome (ItchRO) 
• To assess the impact of volixibat on a composite perinatal outcome in participants 
with ICP on the basis of the following endpoint: 
o Proportion of participants experiencing one or more of the following: 
− Perinatal death, defined as in utero fetal death after randomization or 
known neonatal death up to 28 days after birth 
− Spontaneous preterm delivery, defined as delivery at <37 weeks’ 
gestational age following spontaneous onset of preterm labor or preterm 
premature rupture of the membranes (PPROM) 
− Iatrogenic preterm delivery attributable to ICP or ICP-related 
complications, defined as delivery at <37 weeks’ gestational age 
resulting from medical intervention (i.e., augmentation/induction of 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 7 
labor or cesarean delivery without prior spontaneous onset of preterm 
labor or PPROM with one or more of the following as the indication for 
delivery): 
• Diagnosis of ICP with or without suspected fetal compromise 
• Persistently elevated/increasing sBA 
• Worsening hepatic function 
• Intolerable maternal ICP symptoms 
− Neonatal unit admission for ≥12 hours from birth until hospital 
discharge for one or more of the following indications: 
• Respiratory insufficiency/failure with requirement for oxygen 
supplementation 
• Noninvasive or invasive respiratory support 
• Hemodynamic instability or shock requiring clinical intervention 
• Metabolic acidosis or signs of asphyxia 
• Proven infection 
• Hypoglycemia or feeding problems requiring intravenous (IV) fluids 
or tube feeding 
• Meconium stained amniotic fluid and/or its sequelae (e.g., meconium 
aspiration, etc.) 
1.1.3. 
Safety Objective and Endpoints 
• To assess the safety and tolerability of VLX in participants with ICP on the basis of 
the following endpoints: 
o Incidence of treatment-emergent adverse events (TEAEs), serious adverse 
events (SAEs), adverse events of special interest (AESIs), events of clinical 
interest (ECIs), and AEs that lead to discontinuation of study drug 
o Incidence of clinically significant laboratory abnormalities 
Note: Safety and tolerability are primary objectives for the open-label 
supplemental cohort. 
1.1.4. 
Exploratory Objectives and Endpoints 
The following exploratory objectives and endpoints are applicable to both the primary and 
open-label supplemental cohorts: 
• To assess volixibat drug levels in maternal and fetal plasma and pharmacodynamic 
(PD) markers in maternal blood in participants with ICP on the basis of the following 
endpoints: 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 8 
o Volixibat concentrations in maternal and fetal plasma (from umbilical cord 
sampling) 
Note:  Assessment of maternal/fetal volixibat drug levels is a secondary 
objective for the open-label supplemental cohort. 
o Change in biomarkers of bile acid synthesis, inflammation, and pruritogens 
o Proportion of participants with sBA <40 μmol/L at end of the treatment period  
• To assess the longer-term efficacy of volixibat in participants with ICP on the basis of 
the following endpoints: 
o Mean change from Week 3 to end of study treatment period in total sBA 
concentration  
o Mean change from baseline to end of study treatment period in total sBA 
concentration 
o Association between changes from baseline to Week 3 in total sBA and 
ItchRO as well as their association with the composite perinatal outcome 
• To assess the effect of volixibat on additional perinatal outcomes on the basis of the 
following endpoints: 
o Mean gestational age at delivery 
o Proportion of participants with an early term delivery (37–38 weeks 6 days, 
inclusive) 
o Proportion of participants with a full-term delivery (≥39 weeks) 
o Proportion of participants experiencing a perinatal death 
o Proportion of participants with a spontaneous preterm delivery 
o Proportion of participants with an iatrogenic preterm delivery attributable to 
ICP 
o Proportion of neonates requiring neonatal intensive care unit (NICU) 
admission for ≥12 hours between birth and hospital discharge 
o Proportion of neonates with meconium-stained amniotic fluid at delivery 
o Proportion of participants requiring rescue medication for ICP 
o Proportion of neonates with Apgar score <7 at 5 minutes of life  
o Mean birth weight percentile 
o Mean placental weight percentile 
o Proportion of neonates with umbilical cord pH <7.0 at birth 
o Means for umbilical cord blood sBA, total cholesterol, LDL cholesterol, and 
glucose 
o Mean maternal estimated blood loss at delivery 
o Mean time from randomization to delivery 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 9 
• To evaluate the effect of volixibat on additional measures of pruritus efficacy and 
quality of life in participants with ICP on the basis of the following endpoints: 
o Change from baseline in the 5-D Itch Scale 
o Change from baseline in Clinician Scratch Scale (CSS) 
o Change from baseline in EuroQoL 5-dimension, 5-level (EQ-5D-5L)  
o Change from baseline in Patient-Reported Outcomes Measurement 
Information System (PROMIS) Short Form (SF) Fatigue 7a  
o Change from baseline in PROMIS SF Sleep Disturbance 
o Change from baseline in Patient Impression of Severity-Itch (PIS-Itch) 
o Patient Global Impression of Change-Itch (PGIC-Itch) 
• To assess the impact of volixibat on healthcare utilization in participants with ICP on 
the basis of the following endpoints: 
o Number and duration of medical care encounters, including surgeries and 
other selected procedures (inpatient and outpatient) 
o Dates and duration of hospitalization (total days or length of stay, including 
duration by wards [e.g., intensive care unit]) 
o Number and type of diagnostic and therapeutic tests and procedures 
o Outpatient medical encounters and treatments (including physician or 
emergency department visits, tests and procedures, and medications) 
1.2. 
Study Design 
This is an operationally seamless adaptive clinical study that will consist of 2 parts. 
Part 1:   
Proof of Concept, Dose Ranging, Pharmacokinetics, and Interim Analysis 
After a screening period of up to 10 days, eligible participants will be identified for one of 
two cohorts, defined as follows: 
• Primary cohort:  Participants with ICP with a screening sBA level ≥20 μmol/L will be 
randomized with stratification (based on gestational age [<32 weeks or ≥32 weeks] at 
randomization, presence/absence of gestational diabetes, and highest sBA before 
randomization [<40 μmol/L, ≥40 μmol/L to <100 μmol/L, or ≥100 μmol/L]) in a 
3-arm (1:1:1), double-blind fashion to receive volixibat 20 mg BID, volixibat 80 mg 
BID, or placebo. 
• Supplemental cohort:  Up to 30 participants with ICP with screening sBA level from 
≥15 to <20 µmol/L will be randomized (based on gestational age at randomization 
and presence/absence of gestational diabetes) in a 2-arm (1:1), open-label fashion to 
receive volixibat 20 mg BID or volixibat 80 mg BID. 
Study treatment dosing will begin on Day 1 and continue until end of the study treatment 
period, defined as the day of delivery.  Study visits to assess safety, plasma concentrations of 
volixibat, pharmacodynamics, and efficacy will be conducted weekly from baseline until 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 10 
delivery.  Because alternative measures may be implemented when necessary for public 
health or other emergency situations, and when sufficient to help ensure the safety of study 
participants, some visits may be conducted as a home health or remote visit at the discretion 
of the investigator upon approval by the medical monitor or designee and in accordance with 
local and regional regulations (see Protocol Appendix 10).  Participants will also enter 
ItchRO assessments into an electronic diary (eDiary) once daily.  Use of limited rescue 
therapies for ICP will be permitted for participants who meet protocol-specified criteria. 
A single, formal interim analysis at the end of Part 1 (i.e., after the last study visit for the 60th 
participant in the primary cohort) that will involve a total of approximately 60 participants 
(20 per arm) in the primary cohort only will be performed.  Data from Part 1 will also be 
combined with Part 2 and included in the overall safety summaries; however, because this is 
an operationally seamless adaptive study, efficacy results of participants in Part 1 will not be 
combined with those from Part 2 for the statistical inference performed in Part 2.  Due to the 
seamless adaptive nature of the study, participants may continue to be accrued after the 
60 participants in Part 1 have been enrolled.  Under this scenario, participants randomized to 
placebo and the selected volixibat dose will be used in the analysis in Part 2.  Participants 
randomized to an unselected volixibat dose will not be part of the analysis in Part 2 but will 
be included within safety summaries. 
The interim analysis at the conclusion of Part 1 will be performed by the sponsor and will 
inform the dose to be explored within Part 2 of the study.  Separately, a chartered, 
independent data monitoring committee (IDMC) will monitor unblinded maternal and fetal 
safety/plasma drug level data on an ongoing basis during this study (throughout Parts 1 and 
2), with the initial IDMC meeting (post-study start) to be held after 12 participants in the 
primary cohort complete the study; cadence for subsequent meetings will be outlined in the 
IDMC charter.   
Part 2:   
Confirmation of Safety and Efficacy with Selected Dose 
The second stage will constitute a second double-blind, randomized, placebo-controlled 
phase comparing the selected volixibat dose versus placebo for superior efficacy.  For Part 2, 
it is anticipated that approximately 200 participants (100 per arm) will be randomized. 
Study visits to assess safety, pharmacodynamics, efficacy, and plasma concentrations of 
volixibat in all participants will be conducted weekly from baseline until delivery; sampling 
for volixibat concentrations may be discontinued in Part 2 if Part 1 results demonstrate 
consistently negligible or below the limit of quantitation (LOQ) concentrations in maternal 
and umbilical cord (fetal) plasma.  Because alternative measures may be implemented when 
necessary for public health or other emergency situations and when sufficient to help ensure 
the safety of study participants, some visits may be conducted as a home health or remote 
visit at the discretion of the investigator upon approval by the medical monitor or designee 
and in accordance with local and regional regulations.  Participants will also enter ItchRO 
assessments into an eDiary once daily.  Use of limited rescue therapies for ICP will be 
permitted for participants who meet protocol-specified criteria.  
In both Part 1 and Part 2, safety assessments will include AEs, clinical laboratory tests, vital 
signs, and physical examinations.  Additional fetal safety assessments will include serial 
ultrasounds to assess fetal growth and nonstress tests (NSTs)/cardiotocography (CTG) or 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 11 
fetal biophysical profile (BPP).  Assessment of plasma concentrations of volixibat will be 
obtained in maternal plasma and umbilical cord plasma (when possible) at single time points, 
with no formal pharmacokinetic (PK) parameter analysis planned.  PD assessments will 
include bile acids alongside other biomarkers. 
The sponsor plans to continue formal safety and efficacy monitoring via a chartered IDMC 
throughout the study; this will include AE monitoring specifications.   
1.3. 
Sample Size Determination 
For the interim analysis at the conclusion of Part 1, 60 participants will have been 
randomized 1:1:1.  Part 1 of the study is designed for estimation without formal statistical 
testing; hence, there are no formal power considerations.  With 20 participants per arm and 
assuming a (pooled) standard deviation of 25, a 95% confidence interval (CI) for the 
difference between each volixibat arm and placebo would have a half width of 16.   
For the power calculations for Part 2, it is assumed that only a single dose will be selected at 
the end of Part 1, and a 2-sided alpha 0.05 will be used to test whether there is a difference 
between the two groups.  Thus, for Part 2, a sample size of 100 participants per arm has 80% 
power to detect an effect size of 10 with standard deviation of 25.  Power was calculated 
using SAS, version 9.4.  
Up to 30 additional participants will be enrolled in an open-label supplemental cohort 
consisting of participants with ICP with screening sBA from ≥15 to <20 µmol/L in a 1:1 
manner to the two doses of volixibat. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 12 
2. 
TYPE OF PLANNED ANALYSIS 
2.1. 
Interim Analyses (Part 1) 
A single, formal interim analysis will be performed at the end of Part 1 involving a total of 
approximately 60 participants (20 per arm) in the primary cohort only.   
2.2. 
Supplemental Cohort Analysis 
Once the last participant in the supplemental cohort has completed the study, an analysis of 
the supplemental cohort will be performed. If the supplemental cohort is not fully enrolled by 
the time of the interim analysis, a separate analysis of the supplemental cohort will be 
conducted to help inform dose selection for Part 2.  
2.3. 
Final Analysis (Part 2) 
A final analysis will be performed after all participants have completed the study. The 
primary focus of this analysis will be Part 2, but it will include a summary of Part 1, Part 2, 
and the supplemental cohort. Each of these analyses will be presented separately. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 13 
3. 
GENERAL CONSIDERATIONS FOR DATA ANALYSES 
Unless otherwise specified, analyses will be conducted separately on both the primary cohort 
and the open-label supplemental cohort.  Of note, a pooled safety analysis combining the 
primary and open-label supplemental cohorts may be considered. 
All inferential statistical tests will be 2-sided.  Summary statistics for continuous variables 
will include mean, median, standard deviation, standard error of the mean, minimum, 
maximum, and quartiles.  Summary of categorical variables will include sample size, number 
of occurrences, and percentages (95% CIs will be provided where appropriate). 
The study has 3 separate, self-standing cohorts, and each will have its own separate analyses.  
Primary cohort Parts 1 and 2 will be combined for safety analyses. 
Data from Part 1 will also be combined with Part 2 and included in the overall safety 
summaries; however, since this is an operationally seamless adaptive study, efficacy data 
from participants in Part 1 will not be combined with those from Part 2 for the statistical 
inference performed in Part 2.  Sampling to assess plasma exposures to volixibat may be 
discontinued in Part 2 pending results in Part 1. 
Analysis results will be presented using descriptive statistics.  For categorical variables, the 
number and percentage of participants in each category will be presented; for continuous 
variables, the number of participants (n), mean, standard deviation (SD), median, first 
quartile (Q1), third quartile (Q3), minimum, and maximum will be presented. 
By-participant listings will be presented for all participants in the Intent-to-Treat (ITT) 
Analysis Set and sorted by participants ID number, visit date, and time (if applicable).  Data 
collected on log forms, such as AEs, will be presented in chronological order within each 
participant.  Age, sex at birth, race, and ethnicity will be included in the listings, as space 
permits. 
3.1. 
Analysis Sets 
Analysis sets define the participants to be included in an analysis. Analysis sets and their 
definitions are provided in this section.  The analysis set will be identified and included as a 
subtitle of each table, figure, and listing. 
For each analysis set, the number and percentage of participants eligible for inclusion, as well 
as the number and percentage of participants who were excluded and the reasons for their 
exclusion, will be summarized. 
A listing of reasons for exclusion from analysis sets will be provided by participants. 
The analysis sets are defined in Table 1. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 14 
Table 1 
Analyses Sets 
Analysis Set 
Description 
Enrolled 
All participants who sign the ICF 
ITT 
All randomized participants 
mITT 
All randomized participants who receive at least 1 dose of study drug (partial 
or complete).  Participants will be analyzed according to the treatment to 
which they were randomized.  
PP 
All participants in the mITT population who do not experience any major 
protocol violations 
Safety 
All participants who receive at least 1 dose of study drug.  Participants will be 
classified based upon the treatment they actually receive. 
ICF=informed consent form; ITT=intent-to-treat; mITT=modified intent-to-treat; PP=per-protocol. 
3.2. 
Participants Grouping 
For analyses based on the ITT and mITT Analysis Sest, participants will be grouped 
according to the treatment to which they were randomized.  For analyses based on the PP and 
Safety Analysis Sets, participants will be grouped according to the actual treatment received.  
The actual treatment received will differ from the randomized treatment only when their 
actual treatment differs from randomized treatment for the entire treatment duration. 
3.3. 
Strata and Covariates 
Participants will be randomly assigned to treatment groups via the interactive voice or web 
response system (IXRS). 
• For the primary cohort, a dynamic allocation method, introduced by Pocock and 
Simon (1975) will be adopted to balance participant assignment between treatment 
arms based on the following factors: gestational age (<32 weeks or ≥32 weeks) at 
randomization, presence/absence of gestational diabetes, and highest sBA before 
randomization (<40 μmol/L, ≥40 μmol/L to <100 μmol/L, or ≥100 μmol/L) after 
confirmation of study eligibility.  Participants with highest pre-randomization sBA 
<40 μmol/L shall comprise no more than 33% of the primary cohort for Part 1 and 
Part 2, respectively.  
o For Part 1, in a 1:1:1 ratio via a computer-generated randomization schedule 
to receive volixibat 20 mg BID, volixibat 80 mg BID, or placebo BID 
o For Part 2, in a 1:1 ratio via a computer-generated randomization schedule to 
receive the selected volixibat dose (determined at the interim analysis) or 
placebo BID 
• For the supplemental cohort, participants will be randomized with stratification 
(based on gestational age at randomization and presence/absence of gestational 
diabetes) after confirmation of study eligibility in a 1:1 ratio via a computer-generated 
randomization schedule to receive volixibat 20 mg BID or 80 mg BID. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 15 
Efficacy endpoints will be evaluated using stratification factors as covariates or stratification 
variables for analyses, as specified in Section 6.  If there is an imbalance in presumed 
prognostic baseline characteristics between treatment groups, efficacy evaluations may be 
performed that include these baseline values in efficacy analysis models as covariates; these 
evaluations will be considered sensitivity analyses. 
For efficacy endpoints, the baseline value of the efficacy variable(s) will be included as a 
covariate in the efficacy analysis model. 
3.4. 
Examination of Participant Subgroups 
Subgrouping of participants based on randomization stratification factors will be explored for 
subgroup analyses.  If there is an imbalance between treatment groups in presumed 
prognostic baseline characteristics that are not stratification factors, subgroupings based on 
these imbalanced baseline characteristics will also be explored for analysis of the primary 
and secondary endpoints. The presumed prognostic baseline characteristics include the 
following: 
• Age (≤35 years and >35 years) 
• Race/Ethnicity (Hispanic, White [not Hispanic], South Asian [not Hispanic], and Other) 
• Baseline ItchRO: (4-7 and >7-10) 
• Prior history of ICP (Yes and No) 
3.5. 
Multiple Comparisons 
In order to maintain study-wide Type I error control, a hierarchical testing procedure will be 
used in the comparisons between volixibat and placebo on the primary and secondary 
efficacy endpoints in the mITT population. The hierarchical order for testing the null 
hypotheses is as follows: 
(1) Mean change in total sBA between baseline and Week 3 
(2) Mean change in Adult ItchRO between baseline and Week 3 
(3) The proportion of participants experiencing a composite perinatal outcome 
The effect of such a procedure is that no confirmatory claims can be based on the endpoint(s) 
that have a rank lower than that endpoint whose null hypothesis was the first that could not 
be rejected. Those tests will be considered as exploratory without any formal conclusions 
drawn about them. 
3.6. 
Missing Data and Outliers 
3.6.1. 
Missing Data 
In general, missing data will not be imputed unless methods for handling missing data are 
specified. Exceptions are presented in this document. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 16 
For missing last dosing date of study drug, imputation rules are described in Section 4.2.1.  
The handling of missing or incomplete dates for prior and concomitant medications is 
described in Section 4.3, for the primary efficacy endpoint is described in Section 6.1.5, and 
for AE onset is described in Section 7.1.5.2. 
3.6.2. 
Outliers 
Outliers will be identified during the data management and data analysis process. Sensitivity 
analyses may be conducted to assess the robustness of the results 
3.7. 
Data Handling Conventions and Transformations 
In general, age (in years) on the date of first dose study drug will be used for analyses and 
presentation in listings.  If an enrolled participants was not dosed with any study drug, the 
enrollment date will be used instead of the first dosing date of study drug.  For screen 
failures, the date the informed consent was signed will be used for age calculation.  If only 
the birth year is collected on the CRF, “01 July” will be used for the unknown birth day and 
month for the purpose of age calculation.  If only birth year and month are collected, “01” 
will be used for the unknown birth day. 
Data that are continuous in nature but are less than the lower LOQ or above the upper LOQ 
will be imputed as follows: 
• A value that is 1 unit less than the LOQ will be used to calculate descriptive statistics if 
the datum is reported in the form of “< x” (where x is considered the LOQ).  For 
example, if the values are reported as <50 and <5.0, values of 49 and 4.9, respectively, 
will be used to calculate summary statistics.  An exception to this rule is any value 
reported as <1 or <0.1, etc.  For values reported as <1 or <0.1, a value of 0.9 or 0.09, 
respectively, will be used to calculate summary statistics. 
• A value that is 1 unit above the LOQ will be used to calculate descriptive statistics if the 
datum is reported in the form of “> x” (where x is considered the LOQ).  Values with 
decimal points will follow the same logic as above. 
• The LOQ will be used to calculate descriptive statistics if the datum is reported in the 
form of “≤ x” or “≥ x” (where x is considered the LOQ). 
If methods based on the assumption that the data are normally distributed are not adequate, 
analyses may be performed on transformed data or nonparametric analysis methods may be 
used, as appropriate. 
3.8. 
Analysis Visit Windows 
3.8.1. 
Definition of Study Day 
Study day will be calculated from the first dosing date of study drug and derived as follows: 
• For postdose study days: Assessment Date – First Dosing Date + 1 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 17 
• For days prior to the first dose of study drug: Assessment Date – First Dosing Date  
Therefore, Study Day 1 is the day of first dose of study drug administration. Please note that 
this differs by 1 day relative to days specified within the protocol. 
3.8.2. 
Analysis Visit Windows 
Participant visits might not occur on protocol-specified days.  Therefore, for the purpose of 
analysis, observations will be assigned to analysis windows.  A notable exception to the 
analysis visit windows below is the end of treatment/date of delivery.  This will be 
summarized as its own visit and that will be the value used for endpoints that look at either 
the value or change from baseline to delivery. 
The analysis windows for ItchRO, sBA, hematology, chemistry, coagulation, weight, vital 
Signs, and urinalysis are provided in Table 2. 
The analysis windows for 5-D Itch, EQ-5D-5L, PROMIS Fatigue and Sleep patient reported 
outcomes (PROs), PIS-Itch, PGIC-Itch, and Biomarker samples 
(7α-hydroxy-cholesten-3-one [7αC4], fibroblast growth factor 19 [FGF-19], autotaxin, 
progesterone sulfate, and glucagon-like peptide 1 [GLP-1]) are provided in Table 3. 
The analysis windows for lipid panel and glycated albumin are provided in Table 4. 
The analysis windows for vitamin A, D, and E levels and fetal ultrasound are provided in 
Table 5. 
 
Table 2 
Analysis Visit Windows for ItchRO^, sBA, Hematology*, Chemistry*, 
Coagulation*, Weight, Vital Signs, and Urinalysis 
Nominal Visit 
Nominal Study Day 
Lower Limit 
Upper Limit 
Baseline 
1 
(none) 
1 
Week 1 
8 
2 
11 
Week K 
(K is every week after 
previous visit) 
K*7 + 1 
K*7 – 2 
K*7 + 4 
^ ItchRO is collected daily, but will have weekly averages calculated and results will be grouped according to 
the analysis windows above. 
* Hematology, chemistry, and coagulation are not planned to be collected at the baseline visit. Rather, the 
screening visit (or a subsequent unscheduled visit) will serve as the baseline. 
 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 18 
Table 3 
Analysis Visit Windows for 5-D Itch, CSS, EQ-5D-5L, PROMIS Fatigue and 
Sleep PROs, PIS-Itch, PGIC-Itch, and Biomarker Samples (C4, FGF-19, Autotaxin, 
Progesterone Sulfate, GLP-1) 
Nominal Visit 
Nominal Study Day 
Lower Limit 
Upper Limit 
Baseline* 
1 
(none) 
1 
Week 3 
22 
19 
25 
*PGIC-Itch was not collected at baseline. 
Table 4 
Analysis Visit Windows for Lipid Panel and Glycated Albumin 
Nominal Visit 
Nominal Study Day 
Lower Limit 
Upper Limit 
Baseline 
1 
(none) 
1 
Week 2 
15 
2 
22 
Week K 
(K is every 2 weeks 
after previous visit) 
K*7 + 1 
(K – 1)*7 + 2 
(K+1)*7 + 1 
 
Table 5 
Analysis Visit Windows for Vitamin A, D, and E Levels and Fetal Ultrasound 
Nominal Visit 
Nominal Study Day 
Lower Limit 
Upper Limit 
Baseline 
1 
(none) 
1 
Week 4 
29 
2 
43 
Week K 
(K is every 4 weeks 
after previous visit) 
K*7 + 1 
(K – 2)*7 + 2 
(K+2)*7 + 1 
 
3.8.3. 
Selection of Data in the Event of Multiple Records in an Analysis Visit 
Window 
Depending on the statistical analysis method, single values may be required for each analysis 
window.  For example, change from baseline by visit usually requires a single value, whereas 
a time-to-event analysis would not require 1 value per analysis window. 
If multiple valid, nonmissing, continuous measurements exist in an analysis window, records 
will be chosen based on the following rules if a single value is needed: 
• In general, the baseline value will be the last nonmissing value on or prior to the first 
dose of study drug, unless specified differently.  If multiple measurements occur on the 
same day, the last nonmissing value prior to the time of first dose of study drug will be 
considered as the baseline value.  If these multiple measurements occur at the same time 
or the time is not available, the average of these measurements (for continuous data) will 
be considered the baseline value. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 19 
• For postbaseline values: 
− The record closest to the nominal day for that visit will be selected. 
− If there are 2 records that are equidistant from the nominal day, the later record will 
be selected. 
− If there is more than 1 record on the selected day, the average will be taken, unless 
otherwise specified. 
− If a participant gives birth prior to Week 3, then the value obtained at the date of 
delivery will be analyzed according to the next analysis window after the previous 
visit.  For example, if there was a Week 2 sample provided on Day 15 and then the 
participant delivered on Day 18, the Day 18 record would be mapped to Week 3, even 
though it is contained within the upper bound of the Week 2 analysis window.  This is 
designed to minimize the amount of missing data for the primary endpoint. 
If multiple valid, nonmissing, categorical measurements exist in an analysis window, records 
will be chosen based on the following rules if a single value is needed: 
• For baseline, the last available record on or prior to the date of the first dose of study drug 
will be selected.  If there are multiple records with the same time or no time recorded on 
the same day, the value with the lowest severity will be selected (e.g., normal will be 
selected over abnormal for safety electrocardiogram [ECG] findings). 
• For postbaseline visits, if there are multiple records with the same time or no time 
recorded on the same day, the value with the worst severity within the window will be 
selected (e.g., abnormal will be selected over normal for safety ECG findings). 
 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 20 
4. 
PARTICIPANT DISPOSITION 
4.1. 
Participant Enrollment and Disposition 
A summary of participant enrollment will be provided by treatment group for each 
investigator and overall.  The summary will present the number and percentage of 
participants enrolled.  For each column, the denominator for the percentage calculation will 
be the total number of participants analyzed for that column. 
A similar enrollment table will be provided by randomization stratum.  The denominator for 
the percentage of participants in the stratum will be the total number of enrolled participants.  
If there are discrepancies in the value used for stratification assignment between the IXRS 
and the clinical database, the value collected in the clinical database will be used for the 
summary.  A listing of participants with discrepancies in the value used for stratification 
assignment between the IXRS and the clinical database at the time of data finalization will be 
provided. 
The randomization schedule used for the study will be provided as an appendix to the CSR. 
A summary of participant disposition will be provided by treatment group and part (Part 1 
[double-blind], Part 2 [double-blind], and Open-Label).  This summary will present the 
number of participants screened, the number of participants who met all eligibility criteria 
but were not randomized with reasons participants not randomized, the number of 
participants randomized, and the number of participants in each of the categories listed 
below: 
• Safety Analysis Set 
• Intent-to-Treat 
• Modified Intent-to-Treat 
• Per-Protocol Analysis Set 
• Continuing study drug 
• Completed study drug 
• Did not complete study drug with reasons for premature discontinuation of study drug 
• Continuing study 
• Completed study phase 
• Did not complete the study phase with reasons for premature discontinuation of study 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 21 
For the status of study drug and study completion and reasons for premature discontinuation, 
the number and percentage of participants in each category will be provided. The 
denominator for the percentage calculation will be the total number of participants in the 
Safety Analysis Set corresponding to that column. In addition, a flowchart will be provided 
to depict the disposition. 
The following by-participant listings will be provided by participant identification (ID) 
number in ascending order to support the above summary tables: 
• Reasons for premature study drug or study discontinuation 
• Lot number 
4.2. 
Extent of Study Drug Exposure and Adherence 
Extent of exposure to study drug will be examined by assessing the total duration of exposure 
to study drug and the percent of study drug dose received as specified in the protocol. 
4.2.1. 
Duration of Exposure to Study Drug 
Total duration of exposure to study drug will be defined as last dosing date minus first dosing 
date plus 1, regardless of any temporary interruptions in study drug administration except for 
protocol-specified dose holds and/or dose reductions, and will be expressed in weeks using 
up to 1 decimal place (eg, 4.5 weeks).  If the last study drug dosing date is missing, the latest 
date among the study drug end date, clinical visit date, laboratory sample collection date, and 
vital signs assessment date will be used. 
The total duration of exposure to study drug will be summarized using descriptive statistics 
and using the number (ie, cumulative counts) and percentage of participants exposed through 
the following time periods: 1 day, 3 weeks, 6 weeks, 9 weeks, 12 weeks, 15 weeks, 
18 weeks, and >18 weeks.  Summaries will be provided by treatment group for the Safety 
Analysis Set. 
No formal statistical testing is planned. 
A listing of exposure to the study drug will be provided. 
4.2.2. 
Adherence to Study Drug 
The total number of tablets administered will be summarized using descriptive statistics.  
The presumed total number of doses tablets administered to a participant will be determined 
by the data collected within IXRS for drug accountability using the following formula: 
 
Total Number of Doses Administered =
No. of Doses Dispensed
No. of Doses Returned




−








∑
∑


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 22 
The level of on-treatment adherence to the study drug regimen will be determined by the 
total amount of study drug administered relative to the total amount of study drug expected to 
be administered during a participant’s actual on-treatment period based on the study drug 
regimen. 
The level of on-treatment adherence will be expressed as a percentage using the following 
formula:
Total Amount of Study Drug Administered
On-Treatment Adherence (%) = 
 x 100
Study Drug Expected to be Administered on Treatment






 
Where, the amount of study drug expected to be adminstered on treatment will be derived as 
2 x Duration of Exposure to Study Drug, which is defined in Section 4.2.1.  Descriptive 
statistics for the level of on-treatment adherence with the number and percentage of 
participants belonging to adherence categories (eg, <80%, ≥80 to <90%, ≥90%) will be 
provided by treatment group for the Safety Analysis Set.  
4.3. 
Prior and Concomitant Medications 
Medications collected at screening and during the study will be coded using the current 
version of the World Health Organization (WHO) Drug dictionary. 
4.3.1. 
Prior Non-Antipruritic Medications 
Prior medications are defined as any medications taken prior to the first dose of study drug. 
Prior antipruritic therapies are described in Section 5.4 and not repeated here. 
Prior medications will be summarized by Anatomical Therapeutic Chemical (ATC) drug 
class Level 2 and preferred name using the number and percentage of participants for each 
indication.  A participant reporting the same medication more than once will be counted only 
once when calculating the number and percentage of participants who received that 
medication.  The summary will be ordered alphabetically by ATC medical class and then by 
preferred term in order of descending overall frequency within each ATC medical class. For 
drugs with the same frequency, sorting will be done alphabetically. 
For the purposes of analysis, any medication with a start date prior to the first dosie of study 
drug will be included in the prior medication summary regardless of when the stop date is.  If 
a partial start date is entered the medication will be considered prior unless the month and 
year (if day is missing) or year (if day and month are missing) of the start date are after the 
first dosing date.  Medications with a completely missing start date will be included in the 
prior medication summary, unless otherwise specified. 
Summaries will be based on the Safety Analysis Set.  No formal statistical testing is planned. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 23 
4.3.2. 
Concomitant Medications 
Concomitant medications are defined as medications taken after the first dose of study drug. 
Use of concomitant medications will be summarized by ATC drug class Level 2 and 
preferred name using the number and percentage of participants for each indication. A 
participant reporting the same medication more than once will be counted only once when 
calculating the number and percentage of participants who received that medication. The 
summary will be ordered alphabetically by ATC medical class and then by preferred term in 
descending overall frequency within each ATC medical class. For drugs with the same 
frequency, sorting will be done alphabetically. 
For the purposes of analysis, any medications with a start date prior to or on the first dosing 
date of study drug and continued to be taken after the first dosing date, or started after the 
first dosing date but prior to or on the last dosing date of study drug will be considered 
concomitant medications. Medications started and stopped on the same day as the first dosing 
date or the last dosing date of study drug will also be considered concomitant. Medications 
with a stop date prior to the date of first dosing date of study drug or a start date after the last 
dosing date of study drug will be excluded from the concomitant medication summary. If a 
partial stop date is entered, any medication with the month and year (if day is missing) or 
year (if day and month are missing) prior to the date of first study drug administration will be 
excluded from the concomitant medication summary. If a partial start date is entered, any 
medication with the month and year (if day is missing) or year (if day and month are 
missing) after the study drug stop date will be excluded from the concomitant medication 
summary. Medications with completely missing start and stop dates will be included in the 
concomitant medication summary, unless otherwise specified. Summaries will be based on 
the Safety Analysis Set. No formal statistical testing is planned. 
All prior and concomitant medications (other than per-protocol study drugs) will be provided 
in a by-participant listing sorted by treatment group, participant ID and administration date in 
chronological order. 
4.4. 
Protocol Deviations  
Participants who did not meet the eligibility criteria for study entry, but enrolled in the study 
will be summarized. The summary will present the number and percentage of participants 
who did not meet at least 1 eligibility criterion and the number of participants who did not 
meet specific criteria based on the ITT Analysis Set. A by-participant listing will be provided 
for those participants who did not meet at least 1 eligibility (inclusion or exclusion) criterion. 
The listing will present the eligibility criterion (or criteria if more than 1 deviation) that 
participants did not meet and related comments, if collected. 
Protocol deviations occurring after participants entered the study are documented during 
routine monitoring. The number and percentage of participants with important protocol 
deviations by deviation reason (e.g., nonadherence to study drug, violation of select 
inclusion/exclusion criteria) will be summarized by indication for the ITT Analysis Set. A 
by-participant listing will be provided for those participants with important protocol 
deviations. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 24 
5. 
BASELINE CHARACTERISTICS   
5.1. 
Demographics 
Participants demographic variables (i.e., age, sex, race, and ethnicity) will be summarized 
using descriptive statistics for age, and using number and percentage of participants for sex, 
race, and ethnicity. The summary of demographic data will be provided for the ITT Analysis 
Set. 
A by-participant demographic listing, including the informed consent date, will be provided 
by participant ID number in ascending order. 
5.2. 
Other Baseline Characteristics 
Other baseline characteristics include height (cm), weight (kg), baseline PRO assessments 
(including 5-D Itch, CSS, EQ-5D-5L, PROMIS Fatigue & Sleep PROs, and PIS-Itch) and 
baseline levels of biochemical markers of cholestatis and liver disease (including total sBA, 
ALP, AST, ALT, bilirubin [total and direct], FGF-19, autotaxin, 7αC4, progesterone sulfate, 
and GLP-1). 
Additional disease-specific variables are discussed in Section 5.4. These baseline 
characteristics will be summarized using descriptive statistics for continuous variables and 
using number and percentage of participants for categorical variables. The summary of 
baseline characteristics will be provided for the ITT Analysis Set. No formal statistical 
testing is planned. 
A by-participant listing of other baseline characteristics will be provided by participant ID 
number in ascending order.  
5.3. 
Medical History 
Medical history will be collected at screening for disease-specific and general conditions 
(i.e., conditions not specific to the disease being studied) and coded using Medical Dictionary 
for Regulatory Activities (MedDRA) version 23.1. 
A summary of disease-specific medical history will be provided for the ITT Analysis Set.  
Time since ICP diagnosis (weeks) will be calculated by (date of informed consent of study 
drug – date of ICP diagnosis)/7. Time since ICP diagnosis will be summarized using 
summary statistics for a continuous variable. The other variables will be presented using 
summary statistics for a categorical variable. No formal statistical testing is planned. 
Menstrual history (e.g., last menstrual period [LMP] and date of positive human chorionic 
gonadotropin test), and obstetric history (e.g., previous pregnancies including terminations of 
pregnancy and/or spontaneous abortions, genetic screenings, aneuploidy screening, teratogen 
exposures since LMP/pregnancy, infections [i.e., Covid-19, Zika, HIV, or hepatitis], travel 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 25 
outside the country, history of IVF or other fertility treatments, history of cerclage 
placement) will be obtained. 
General medical history data will not be summarized, but will be listed. 
A by-participant listing of disease-specific and general medical history will be provided by 
participant ID number in ascending order. 
In deriving the time since ICP diagnosis, all partial dates of diagnosis will be identified, and 
the partial dates will be imputed as follows: 
• If day and month are missing but year is available, then the imputed day and month will 
be 01 Jan. 
• If day is missing but the month and year are available, then the imputed day will be the 
first day of the month. 
• Partial date will not be imputed if the year is missing. 
5.4. 
Prior Antipruritic or Prior ICP Therapy 
The number of prior antipruritic and prior ICP therapies will be coded using the international 
reference for medicinal product information (WHODrug) 2020 March version or later and 
summarized by ATC drug class Level 2 and preferred name using the number and percentage 
of participants for each indication using descriptive statistics based on the ITT Analysis Set. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 26 
6. 
EFFICACY ANALYSES 
6.1. 
Primary Efficacy Endpoint 
6.1.1. 
Definition of the Primary Efficacy Endpoint 
The primary efficacy endpoint analysis is defined as the mean change in total sBA 
concentration from baseline to Week 3. 
6.1.2. 
Estimand and Analysis of the Treatment Effect 
The estimand for the treatment effect will be the mean difference between volixibat and 
placebo for the change from baseline in sBA at Week 3.  
The primary analysis will be conducted in the primary cohort using the modified ITT (mITT) 
population.  A restricted maximum likelihood (REML)–based mixed-effects model for 
repeated measures (MMRM) will be used including weekly postbaseline change from based 
line in total sBA during the core study period (double-blind treatment period) through Week 
3, as the dependent variable and the fixed, continuous effects of baseline sBA and gestational 
age, fixed categorical effects of presence/absence of gestational diabetes, treatment group, 
visit, and treatment group by-visit interaction as covariates and participant as a random 
effect.   
The unstructured variance/covariance matrix will be used to model the variances and 
covariances for the time points included in the model.  The unstructured variance/covariance 
does not impose any restrictions on the pattern of the matrix elements.  The use of an 
endpoint 3 weeks after baseline should result in minimal amounts of missing data.  Every 
attempt (e.g., relaxing the convergence criteria, increasing the iteration limit, choosing 
reasonable starting values for the estimates) will be made to ensure convergence using the 
unstructured modeling of within-participant correlations.  However, if the numerical 
algorithm for estimation of the mixed model fails to converge, the following 
variance/covariance matrix structures will be used in the following order:  1) heterogeneous 
Toeplitz, 2) heterogeneous compound symmetry, and 3) heterogeneous autoregressive of 
order 1.  The first (co)variance structure that does not have a convergence problem will be 
the one used for the analysis.  The Kenward-Roger approximation (1997) will be used to 
estimate denominator degrees of freedom. 
The primary efficacy analysis will compare volixibat and placebo using the contrast 
(difference in least squares [LS] means) between treatment groups at Week 3.  Significance 
tests will be based on LS means using a 2-sided significance level (2-sided 95% CIs). 
The null hypothesis for the primary efficacy endpoint of the equality of volixibat and placebo 
is: 
H0: mean change in total sBA baseline and Week 3 in the two treatment groups 
are equal 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 27 
The null hypothesis of equal treatment effect will be rejected if the statistical analysis results 
in a 2-sided p-value for treatment at Week 3 is ≤0.05.  For each cohort, LS means will be 
calculated for each treatment group for each postbaseline visit in the model.  The difference 
between volixibat and placebo change from baseline in sBA will be estimated, with the 
corresponding 2-sided 95% CI constructed for each visit through Week 3.  The change from 
baseline LS means with standard error, 95% CI for the LS means, p-value for testing if the 
LS mean is zero, LS mean difference between treatment groups (volixibat minus placebo) 
with standard error, 95% CI for the LS mean difference, and p-value for testing if the 
treatment LS means are equal will be presented. 
The study will be claimed successful if the hypothesis of no treatment effect on the primary 
efficacy endpoint over the primary cohort in the mITT population from Part 2 is rejected at 
the 0.05 (2-sided) significance level. 
Summary statistics on total sBA by treatment group and visit will also be presented.  In 
addition, a figure with the LS mean ± standard error of change from baseline in total sBA 
will be presented by treatment group and visit.  
In addition, a responder analysis (based on change in total sBA) may be considered. 
Separately, a similar analysis on the open-label supplemental cohort will be performed.  The 
analysis will be identical, except that baseline sBA will not be a covariate used within the 
model. 
6.1.3. 
Intercurrent Events and Handling Strategies 
The following table listed outs some potential intercurrent events that may impact the 
estimation of the primary estimand of the study. For each type intercurrent event, we 
proposed handling strategies: 
Events 
Potential Consequences 
Handling Strategy 
Early discontinuation 
and/or missing because of: 
1. Lack of efficacy; 
physician decision; or 
required prohibited 
medication; 
2.Adverse events or death; 
3. Noncompliance to study 
drug; 
4. Other reasons for 
treatment discontinuations 
• Confounded treatment 
effect 
Hypothetical Policy 
• Sensitivity Analysis: 
− MAR 
− MNAR 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 28 
Concomitant Medications 
• More difficult to pinpoint 
o Administered as needed 
for both active treatment 
and placebo 
o May lead to various 
impacts on participants’ 
treatment/safety/efficacy 
Randomization/Treatment 
Policy 
Other Intrinsic/extrinsic 
factors  
• Stratification factors 
• Age 
• Sex 
• Race/Ethnicity 
• Differentiated treatment 
effects  
Principal Stratum Policy 
• Stratified analyses 
• Subgroup analyses  
• Covariate adjusted 
analyses 
 
6.1.4. 
Rationale for Primary Analysis Method 
The MMRM method has been demonstrated extensively as an appropriate choice for the 
primary analysis in longitudinal confirmatory clinical trials with continuous endpoints 
(Mallinckrodt et al. 2008).  This analysis method, which is from a broader class of 
direct-likelihood analyses methods, makes use of fully and partially observed data sequences 
from individual participants by estimating the covariance between data from different time 
points (Molenberghs and Kenward 2007).  Further, it is often useful to implement MMRM 
using an unstructured approach to modeling both the treatment-by-time means and the 
(co)variances, leading to what is essentially a multivariate normal model wherein treatment 
group means at the primary time point are adjusted to reflect both the actual observed data 
and the projected outcomes from the participants with missing data (Cnaan et al. 1997; 
Molenberghs et al. 2004; Molenberghs and Kenward 2007). 
Despite careful planning and study conduct, the occurrence of missing data cannot be 
completely eliminated.  As a direct likelihood method, the MMRM method is a preferred 
approach for handling missing data in such designs.  MMRM is a full multivariate model in 
nature that avoids potential bias as a predetermined model and operates in a more general 
missing at random (MAR) framework (Mallinckrodt et al. 2001).  Data are considered MAR 
if, conditional upon the independent variables in the analytic model, the missingness depends 
on the observed outcomes of the variable being analyzed but does not depend on the 
unobserved outcomes of the variable being analyzed.  This assumption implies that the 
behavior of the post dropout observations can be predicted from the observed variables, and 
therefore that treatment effect can be estimated without bias using the observed data 
(European Medicines Agency 2010).  For studies of missing data in a controlled clinical trial 
setting, MAR is usually considered as a plausible underlying missing mechanism 
(Molenberghs and Kenward 2007; Siddiqui et al. 2009; Mallinckrodt et al. 2008, 
Mallinckrodt et al. 2013).  The assumption of MAR is often reasonable because, particularly 
in longitudinal studies wherein the evolution of treatment effects is assessed by design over 
time, the observed data and the models used to analyze them can explain much of the 
missingness (Little and Rubin 1987; Verbeke and Molenberghs 2000).  This point may be 
especially relevant in well-controlled studies, in which extensive efforts are made to observe 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 29 
all outcomes and factors that influence them while participants are following protocol-
defined procedures.  Thus, longitudinal clinical trials by their very design aim to reduce the 
amount of missing not at random (MNAR) data (missingness explained by unobserved 
responses), thereby increasing the plausibility of MAR (Mallinckrodt et al. 2008). 
6.1.5. 
Sensitivity Analysis of the Primary Efficacy Endpoint 
Sensitivity and supportive analysis will be performed on the primary efficacy endpoint to 
quantify the possible impact of missing data, intercurrent events and to demonstrate the 
robustness of the conclusions.  See below for details about missing data handling, 
placebo-based imputation, and a tipping-point analysis. 
Furthermore, the primary analysis will be repeated using a hypothetical (de jure) estimand 
where data collected after rescue medication is initiated will be omitted.  This can be viewed 
as addressing a per protocol estimand, or more simply the applicable estimand if all 
participants completed the first 3 weeks of follow-up without any rescue or without any 
missing data. 
6.1.6. 
Missing Data 
Although the assumption of MAR, as used for the primary efficacy analysis method, is often 
reasonable in clinical studies, the possibility of MNAR data cannot be ruled out.  Therefore, 
examining the robustness of the primary analysis results under MNAR is desired.  Both a 
MNAR- and MAR-based analyses will be the basis upon which sensitivity of missing data is 
assessed. 
Sensitivity analyses to deal with missing data and intercurrent events will be based on 
multiple imputation methods where missing values are imputed individually under different 
assumptions.  Multiple imputation is a simulation-based approach where missing values are 
replaced using an appropriate stochastic model given the observed data and covariates, 
creating multiple completed data sets.  These completed datasets are then analyzed using 
standard analysis methods (i.e., MMRM), and the different parameter estimates across the 
datasets are then combined to produce a unique point estimate and standard error taking into 
account the uncertainty of the imputation process.  The following 2 sensitivity analysis 
models, one based on the standard MAR approach and the other based on the MNAR 
approach, will be used to examine robustness of the primary analysis results under the impact 
of missing data and intercurrent events. 
6.1.7. 
Complete Multiple Imputation Differentiating Interrcurrent Events 
For participants with complete data up to a particular visit, a distribution will be assumed for 
the assessments includes the outcome at that visit based on predefined missing categories and 
types of intercurrent events. The missing data then will be imputed based on specified 
algorithm which draws samples based on the prespecified distribution and algorithm. This 
process will be repeated a given number of times, resulting in the same number of complete 
analysis data sets. The MMRM analyses then will be performed separately for each of the 
completed analysis data sets, and the results will be combined into one multiple imputation 
inference (Little and Yau 1996; Schafer 1997).  Example SAS code is provided in 
Appendix 3. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 30 
Imputation distribution: 
The imputation distribution for the missing change from baseline in sBA at visit t will be 
assumed to follow a normal distribution. All randomized participants will be classified in one 
of the three categories based on the following rules: non-missing category, missing category 
1, or missing category 2,  
Non-missing category: Participants who have completed sBA assessment at baseline and 
Week 3 and have the change from baseline Week 3. 
Missing category 1: Participants who discontinued treatment because of adverse events, lack 
of efficacy, noncompliance with study drug, death, physician decision, or required prohibited 
medication. These participants have missing change from baseline in sBA at visits including 
Week 3. 
Missing category 2: Participants who discontinued treatment because of all other reasons 
other than the ones listed in category 1 and have missing the change from baseline in sBA at 
visits including Week 3, or participants who have completed 3 weeks treatment duration but 
are missing the change from baseline in sBA at visits including Week 3. 
Imputation algorithm: 
We use the following algorithm that relates the mean of the missing change from baseline in 
sBA at visit t to the missing categories defined above. The algorithm will be implemented 
independently within each treatment group: 
• 
Missing category 1: randomly draw a sample from the normal distribution 
𝑁𝑁(𝜇𝜇25, 𝜎𝜎2), where 𝜇𝜇25 is the 25th percentile of the non-missing change from baseline 
in sBA at visit t and 𝜎𝜎2 is the sample variance estimated using the non-missing 
change from baseline at visit t. 
• 
Missing category 2: randomly draw a sample from the normal distribution 𝑁𝑁(𝜇𝜇, 𝜎𝜎2), 
where 𝜇𝜇 is the mean of the non-missing change from baseline in sBA at visit t and 𝜎𝜎2 
is the sample variance estimated using the non-missing change from baseline at visit 
t. 
Analysis model: 
The complete MI method is described below: 
• 
Impute missing values using the normal distribution specified in the above algorithm 
to impute values for all participants visit t. After imputation, all participants in the 
defined analysis population(s) will have non-missing change from baseline in sBA at 
visit t. 
• 
Repeat the imputation for visits t+1, …, Week 3, until measurements at visits from 
visit t to Week 3 are imputed to form a complete dataset. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 31 
• 
Repeat the process K (K=5) times, using the procedure described above to form K 
imputed complete datasets. 
• 
Fit the MMRM model including terms for treatment, and all other terms as in the 
primary analysis model to each imputed dataset, to estimate the change from baseline 
during at Week 3 and its variance.  
• 
Combine the results from the K imputed datasets using the SAS procedure 
MIANALYZE to derive the MI estimator. 
We fit the analysis model (MMRM model specified before) to the kth imputed dataset, 
denoting the corresponding estimate of the variance Vk.  The MI estimator, 𝜃𝜃෨𝑀𝑀𝑀𝑀, is the 
average of the K individual estimators. 
The estimated variance of 𝜃𝜃෨𝑀𝑀𝑀𝑀 is a combination of the between- and within-imputation 
variability as follows: 𝑉𝑉𝑀𝑀𝑀𝑀= 𝑊𝑊+ ቀ1 +
1
𝐾𝐾ቁ, where 𝑊𝑊=
1
𝐾𝐾∑
𝑉𝑉𝑘𝑘
𝐾𝐾
𝑘𝑘=1
 is the within-imputation 
variability and is 𝐵𝐵=
1
𝐾𝐾−1 ∑
(𝜃𝜃෨𝑘𝑘−
𝐾𝐾
𝑘𝑘=1
𝜃𝜃෨𝑀𝑀𝑀𝑀)2 is the between-imputation variance. The statistic 
𝑇𝑇=
𝜃𝜃෩𝑀𝑀𝑀𝑀−𝜃𝜃
ඥ𝑉𝑉𝑀𝑀𝑀𝑀 has an approximate 𝑡𝑡𝑉𝑉 distribution 
6.1.8. 
Tipping Point Analysis 
An additional sensitivity analysis using the tipping-point approach will be conducted to 
assess the robustness of the primary analysis approach.  If it is plausible that, for the active 
treatment group, the distribution of missing primary endpoint responses has a smaller 
expected reduction than that of the corresponding distribution of the observed primary 
endpoint responses, the conclusion under the MAR assumption should be examined.  It is 
desired to impose a fixed and definite set of quantities to encapsulate the change in efficacy 
associated with withdrawal (missing) for the active treatment group, and independently for 
the placebo group.  The tipping point multiple imputation analysis as described by Ratitch et 
al. (2013) will be applied.  Tipping point analysis is a means of exploring the influence of 
missingness on the overall conclusion from statistical inference by positing a wide spectrum 
of specifications regarding the missingness mechanism (from less pessimistic to more 
pessimistic).  The analysis finds a (tipping) point in this spectrum of specifications, at which 
conclusions change from being favorable to the experimental treatment to being neutral.  The 
analysis will be based on the following procedure: 
1. 
The missing data are filled in m (m = 10) times to generate m complete data sets 
assuming that we do not differentiate missing data category (similar to assuming the 
algorithm for missing category 2). 
2. 
The m complete data sets are analyzed by using standard procedures. 
3. 
The results from the m complete data sets are combined for the inference. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 32 
4. 
Repeat the steps #1 to generate multiple imputed data sets, with a specified shift 
parameter that adjust the imputed values for observations in the relevant treatment 
group independently. 
5. 
Repeat the step 2 for the imputed data sets with shift parameter applied. 
6. 
Repeat the step 3 to obtain the p-value to see if the p-value is still ≤0.05. 
7. 
Repeat the steps 4-6 with more stringent shift parameter applied until the p-value 
>0.05. 
After such a tipping point is determined, clinical judgment can be applied as to the 
plausibility of the specifications underlying this tipping point.  The tipping point can be 
identified while the result is no longer statistically significant.  This imputation analysis uses 
a specified sequence of shift parameters, which adjust the imputed values for observations in 
the active treatment group and independently for the placebo group. A sample of SAS code 
for sensitivity analysis using the tipping-point method is provided in Appendix 3. 
6.2. Secondary Efficacy Endpoints 
The secondary efficacy endpoints (see Section 1.1.2) are designed to evaluate the efficacy of 
volixibat versus placebo for the treatment of pruritus in participants with ICP as well as 
composite perinatal outcomes.  
1. The secondary efficacy endpoint for pruritus is defined as the mean change from 
baseline to Week 3 in the weekly average worst daily itch score as measured by the 
Adult ItchRO.  The worst daily itch score is averaged over the 7 days preceding 
baseline and over the 7 days preceding each week through Week 3.  If more than 3 
days of assessments are missing from a given week, then that weekly average will be 
set to missing.  The analysis of the Adult ItchRO will use an MMRM with a 
comparable model to that for the primary endpoint. 
2. The secondary efficacy endpoint for composite perinatal outcomes is defined as the 
proportion of participants that experience any of the 4 outcomes specified in 
Section 1.1.2.  For this responder-type endpoint, the number and proportion of 
participants that are considered a “responder” will be summarized by treatment group 
at Week 3 and analyzed using a stratified Cochran-Mantel-Haenszel (CMH) test to 
calculate the p-value for the difference between treatment groups.  The p-value from 
the CMH test will be the basis of the hypothesis testing.   
Additionally, the baseline stratum weighted difference in the response rate (P1 – P2) 
and its 95% CI will be calculated based on stratum-adjusted Mantel-Haenszel (MH) 
proportions as described as follows (Koch 1989), where stratification factors include 
gestational age, baseline ItchRO score, and gestational diabetes: 
P1 – P2 ± Z(1 – α/2) * SE(P1 – P2) 
where 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 33 
• (P1 −P2) =
∑whdh
∑wh  is the stratum-adjusted MH proportion difference, where dh =
p1h −p2h is the difference in the response rate between treatment groups 1 and 2 
in stratum h (h=1 to 12). 
• wh =
n1hn2h
n1h+n2h is the weight based on the harmonic mean of the sample size per 
treatment group for each stratum where n1h and n2h are the sample sizes of the 
treatment groups 1 and 2 in stratum h. 
• SE(P1 −P2) = ඨ
∑wh
2൤
p1h
∗
(1−p1h
∗
)
n1h−1
+
p2h
∗
(1−p2h
∗
)
n2h−1
൨
(∑wh)2
, where p1h
∗
=
m1h+0.5
n1h+1  and p2h
∗
=
m2h+0.5
n2h+1 . m1h and m2h are the number of participants who are “responders” in 
treatment groups 1 and 2 in stratum h. 
• α = 0.05 
• Z(1 – α/2) = Z0.975 = 1.95996 is the 97.5th percentile of the normal distribution 
Note that if the computed lower confidence bound is less than -1, the lower bound 
is defined as -1. Similarly, if the computed upper confidence bound is greater than 
1, the upper bound is defined as 1.Furthermore, as supportive analyses, a Logistic 
Regression (LR) estimator approach (Ge et al. 2011), as well as a logistic 
regression model with baseline sBA, gestational age, and presence/absence of 
gestational diabetes as covariates will be run.  The model assumptions of the 
logistic regression model are not considered a concern because a randomized 
study has comparable distributions of the treatment groups for covariates and 
factors for stratification, although they may impact the interpretation of estimated 
parameters for the covariates.  Most importantly, a logistic regression model 
addresses estimands that are conditional on the covariates in the model, with these 
estimands sometimes being called participant-specific, and express the extent of 
efficacy of a treatment that a participant might expect on the basis of her 
covariates, although they tend to be further from the null for an effective 
treatment than population average estimand.  A randomization-based version of 
logistic regression will also be considered.  It is robust to model assumptions and 
it has a population average estimand that is the same as the unadjusted odds ratio 
for comparing two treatments (Zink and Koch 2012). 
6.3. Exploratory Efficacy Endpoints 
The exploratory efficacy endpoints are defined in Section 1.1.3. 
Continuous endpoints will be summarized using descriptive statistics.  A p-value will be 
computed for between treatment comparisons using a van Elteren (vE) test (van Elteren 
1960).  The Wilcoxon–Mann–Whitney (WMW) test (Mann and Whitney 1947; 
Wilcoxon 1945) is widely used nonparametric approach to compare two treatments.  In the 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 34 
presence of stratum factors such as gestational age or ItchRO(Obs) Score, the van Elteren 
test, a stratified WMW test, can be used to adjust for the stratification factors.  It was shown 
by Qu et al. (2008) that vE test preserves the type I error rate regardless of the existence of 
the stratum effects, and is better than the WMW test when the stratum effects are large. 
A non-strata adjusted 95% CI for the difference in means between treatment groups will also 
be presented.  A test of equality of variances will be performed.  If the null hypothesis that 
the variances are equal is rejected, then the 95% CI will be constructed using a Satterthwaite 
approximation.  Otherwise, the variances will be pooled. 
For categorical endpoints, the number and percent for each category will be displayed.  For 
responder-type analyses, within a treatment group, an approximate 95% CI will be presented 
using a stratified Wilson confidence interval (Yan and Su 2010).  A 95% CI comparing two 
treatment groups based on stratum-adjusted MH proportions as described in Section 6.2 will 
also be generated.  A stratified CMH test will be used to calculate the p-value for the 
difference between treatment groups.  The method is applicable to the following endpoints: 
• Proportion of participants with an early term delivery (37–38 weeks 6 days, inclusive) 
• Proportion of participants with a full-term delivery (≥39 weeks) 
• Proportion of participants experiencing a perinatal death 
• Proportion of participants with a spontaneous preterm delivery 
• Proportion of participants with an iatrogenic preterm delivery attributable to ICP 
• Proportion of neonates requiring neonatal intensive care unit (NICU) admission for 
≥12 hours between birth and hospital discharge 
• Proportion of neonates with meconium-stained amniotic fluid at delivery 
• Proportion of participants requiring rescue medication for ICP 
• Proportion of neonates with Apgar score <7 at 5 minutes of life  
• Proportion of neonates with umbilical cord pH <7.0 at birth 
“Responder” analyses for composite perinatal outcomes will be performed using baseline 
sBA and ItchRO and the change at Week 3 values in sBA and ItchRO as covariates and, 
separately, using the Week 3 values themselves (instead of the change at Week 3). 
The change in total sBA from Week 3 (primary endpoint) to delivery will be considered, and 
the difference between treatment groups will be tested using a randomization-based version 
of rank analysis of covariance (ANCOVA) (Stokes et al. 2012).  In a similar manner, the 
change from baseline in total sBA concentration to the time of delivery will also be explored.  
An additional analysis will be performed that examines the change from baseline to delivery 
but that averages across the last two time points on or prior to delivery.  Similar analyses will 
be performed for Adult ItchRO.  Associations between the changes from baseline to Week 3 
in total sBA and Adult ItchRO will be assessed using Pearson’s and Spearman’s correlation 
coefficient.  Additionally, a scatterplot of two variables will also be produced.   


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 35 
The following endpoints will be summarized by treatment arm and the summary statistics by 
treatment arm and the treatment differences will be tabulated: 
• Mean gestational age at delivery 
• Mean birth weight percentile 
• Mean placental weight percentile 
• Means for umbilical cord blood sBA, total cholesterol, LDL cholesterol, and glucose 
• Mean maternal estimated blood loss at delivery 
• Mean time from randomization to delivery 
Further exploratory efficacy endpoints include continuous and binary endpoints on additional 
perinatal outcomes.  The analysis of continuous endpoints will follow the same approach as 
other exploratory efficacy endpoints.  Binary outcomes will be analyzed in the same manner 
as the secondary efficacy endpoint for composite perinatal outcomes. 
The secondary endpoint of composite perinatal outcomes will also be explored using an 
ordinal scale, with ranks assigned according to the severity of the outcomes specified within 
Section 3.2.   
Table 6 
Perinatal Outcome Severity Scoring 
Perinatal Outcome 
Score 
Perinatal death 
4 
Spontaneous preterm delivery 
3 
Iatrogenic preterm delivery attribute to ICP or ICP-related complications 
2 
Neonatal unit admission for ≥12 hours from birth until hospital discharge for any of the 
reasons listed in Section 1.1.3 
1 
No perinatal outcome 
0 
The score is assigned according to the most severe outcome following the order shown 
above.  If a participant experiences perinatal death, spontaneous preterm delivery, or 
iatrogenic preterm delivery attributed to ICP or ICP-related complications AND neonatal unit 
admission for ≥12 hours from birth until hospital discharge for any of the reasons listed in 
Section 3.2, the score will be adjusted by 0.5.  For example, if a participant has spontaneous 
preterm delivery followed by a neonatal unit admission, the score would be 3+0.5=3.5, where 
the 3 comes from the spontaneous preterm delivery and the 0.5 comes from the fact that 
neonatal unit admission occurred.  This will be analyzed using a stratified log rank test that 
provides more weight to the more severe outcomes and will employ a randomization-based 
covariance adjustment (Zink and Koch 2012). 
Change in biomarkers of bile acid synthesis, inflammation, and pruritogens as well as the 
proportion of participants with sBA <40 μmol/L at the end of the treatment period will also 
be explored.  The change in biomarkers will follow the same approach as other exploratory 
efficacy endpoints described above.  The proportion of participants with sBA <40 μmol/L at 
the end of the treatment period will be analyzed in the same manner as the secondary efficacy 
endpoint for composite perinatal outcomes. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 36 
7. 
SAFETY ANALYSES 
Safety summaries will be separated by the portion of the study in which they occurred. There 
are two parts of the double-blind part of the study and the open-label supplemental cohort.  
7.1. 
Adverse Events and Deaths 
Adverse events are captured both for the participant (mother) and their child. As a result, 
summaries and listings will be presented separately. 
7.1.1. 
Adverse Event Dictionary 
Clinical and laboratory AEs will be coded using the MedDRA version 23.1. System organ 
class (SOC), high-level group term (HLGT), high-level term (HLT), preferred term (PT), and 
lower-level term (LLT) will be provided in the AE dataset. 
7.1.2. 
Adverse Event Severity 
Adverse events are graded by the investigator as Grade 1, 2, 3, 4, or 5 according to Common 
Terminology Criteria for Adverse Events (CTCAE) Version 5.0. The severity grade of events 
for which the investigator did not record severity will be categorized as “missing” for tabular 
summaries and data listings. The missing category will be listed last in summary 
presentation. 
7.1.3. 
Relationship of Adverse Events to Study Drug 
Related AEs are those for which the investigator selected “Related” on the AE CRF to the 
question of “Relationship to Study Drug(s).” Relatedness will always default to the 
investigator’s choice, not that of the medical monitor. Events for which the investigator did 
not record relationship to study drug will be considered related to study drug for summary 
purposes. However, by-participant data listings will show the relationship as missing. 
7.1.4. 
Serious Adverse Events 
Serious adverse events (SAEs) will be identified and captured as SAEs if the AEs met the 
definitions of SAEs that were specified in the study protocol. SAEs captured and stored in 
the clinical database will be reconciled with the safety database before data finalization. 
7.1.5. 
Treatment-Emergent Adverse Events  
7.1.5.1. 
Definition of Treatment-Emergent Adverse Events 
Maternal treatment-emergent adverse events (TEAEs) are defined as AEs that start or 
deteriorate on or after the first dose of study medication and no later than 7 days following 
the last dose of study medication.  For any participants (i.e., mothers) who die during the 
study and the date of death is between the date of the first dose of study medication and the 
date of study discontinuation (as entered by the site), inclusive, all AEs (including those 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 37 
resulting in death) that occur during the study will be considered as TEAEs irrespective of 
the last dose and will be included in the TEAE summaries.  All summaries of AEs will be 
based on TEAEs unless specified otherwise. 
For newborns, all reported AEs will be considered TEAEs for the purpose of summaries. 
7.1.5.2. 
Incomplete Dates 
If the onset date of the AE is incomplete and the AE stop date is not prior to the first dose of 
study drug, then the month and year (or year alone if month is not recorded) of onset 
determine whether an AE is treatment emergent. The event is considered treatment emergent 
if both of the following 2 criteria are met: 
• The AE onset is the same as or after the month and year (or year) of the first dosing date 
of study drug, and 
• The AE onset date is the same as or before the month and year (or year) of the date 
corresponding to 7 days after the date of the last dose of study drug  
An AE with completely missing onset and stop dates, or with the onset date missing and a 
stop date later than the first dosing date of study drug, will be considered to be treatment 
emergent. In addition, an AE with the onset date missing and incomplete stop date with the 
same or later month and year (or year alone if month is not recorded) as the first dosing date 
of study drug will be considered treatment emergent. 
7.1.6. 
Summaries of Adverse Events and Deaths 
Treatment-emergent AEs will be summarized based on the Safety Analysis Set. 
7.1.6.1. 
Summaries of AE Incidence 
The number and percentage of participants who experienced AEs described below will be 
provided and summarized by SOC and PT unless otherwise indicated: 
• TEAEs 
• TEAEs of Grade 3 or higher (by SOC, PT and maximum severity) 
• Treatment-related TEAEs (TRAEs) 
• TRAEs of Grade 3 or higher (by SOC, PT and maximum severity) 
• Serious TEAEs 
• Serious TRAEs 
• TEAEs leading to discontinuation of study drug 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 38 
• TEAEs leading to death 
• AESIs 
• ECIs 
A brief, high-level summary of AEs described above will be provided by the number and 
percentage of participants who experienced the above AEs. 
Multiple events will be counted only once per participant in each summary.  Adverse events 
will be summarized and listed first in alphabetic order of SOC and then by PT in descending 
order of total frequency within each SOC.  For summaries by severity, the most severe 
severity will be used for those AEs that occurred more than once in a given participant during 
the study. 
In addition to the above summary tables, TEAEs, TEAEs of Grade 3 or higher, TRAEs, 
TRAEs of Grade 3 or higher, serious TEAEs, TEAEs leading to discontinuation of study 
drug, AESIs, and ECIs will be summarized by PT only in descending order of total frequency 
within indication. 
Furthermore, data listings will be provided for the following: 
• All AEs, indicating whether the event is treatment emergent 
• All AEs of Grade 3 or higher 
• TRAEs 
• TRAEs of Grade 3 or higher 
• AESIs 
• ECIs 
• SAEs 
• AEs leading to death (ie, outcome of death) 
• AEs leading to discontinuation of study drug 
If there are no participants who meet the criteria for any of these listings, the listing will be 
generated and will contain a statement, “No <criteria> were reported.”  For example, if there 
are no AEs leading to death on study, the statement would be “No AEs leading to death were 
reported.” 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 39 
7.1.7. 
Additional Analysis of Adverse Events 
Furthermore, exposure adjusted incidence rates (EAIR) will be provided for each AE 
reported.  For EAIR analyses, the following convention will be used to calculate the 
denominator (i.e., population-level time at-risk) for these analyses.  The population-level 
time at-risk includes only the time each participant is at risk.  The start date of at-risk time is 
the date of first dose of study drug, and the last date of at-risk time is the start date of the 
occurrence of the AE or is censored at completion/early termination, whichever is earlier. 
While no formal hypothesis testing or margin selection is planned, the risk difference and 
corresponding exact 95% CI (using the method of Chan and Zhang [1999]) will be presented 
to compare treatment groups with regards to AESIs and ECIs. 
The TEAE by PT summary will also be repeated by the subgroups defined in Section 3.4. 
Incidence/prevalence plots of common adverse events may be explored.  
7.2. 
Laboratory Evaluations 
Laboratory data collected during the study will be analyzed and summarized using both 
quantitative and qualitative methods. Summaries of laboratory data will be provided for the 
Safety Analysis Set and will include data collected up to the last dose of study drug plus 7 
days for participants who have permanently discontinued study drug, or all available data at 
the time of the database snapshot for participants who were ongoing at the time of an interim 
analysis.  The analysis will be based on values reported in conventional units.  When values 
are below the LOQ, they will be listed as such, and the closest imputed value will be used for 
the purpose of calculating summary statistics as specified in Section 3.7.  Hemolyzed test 
results will not be included in the analysis, but they will be listed in by-participant laboratory 
listings. 
A by-participant listing for laboratory test results will be provided by participant ID number 
and time point in chronological order for hematology, serum chemistry, and urinalysis 
separately. 
No formal statistical testing is planned. 
7.2.1. 
Summaries of Numeric Laboratory Results 
Descriptive statistics will be provided by indication for each laboratory test specified in the 
study protocol as follows: 
• Baseline values  
• Values at each postbaseline time point 
• Change and percentage change from baseline at each postbaseline time point 
A baseline laboratory value will be defined as the last measurement obtained on or prior to 
the date/time of first dose of study drug.  Change from baseline to a postbaseline visit will be 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 40 
defined as the visit value minus the baseline value.  The mean, median, Q1, Q3, minimum, 
and maximum values will be displayed to the reported number of digits; SD values will be 
displayed to the reported number of digits plus 1. 
7.2.2. 
Shifts Relative to the Baseline Value 
For all laboratory tests, shift tables will be presented by showing changes in results from 
baseline value (low, normal, and high) to the worst postbaseline result (low, normal, high, or 
low and high).  A participant would have a worst postbaseline result of normal if all 
postbaseline results are within the normal reference range.  The value of “low and high” 
would be used if the participant has postbaseline values that are below the normal reference 
range at one visit and above the normal reference range at another visit. 
 
7.3. 
Body Weight, Height, and Vital Signs 
Descriptive statistics will be provided indication for body weight, height, body mass index 
(BMI), and vital signs as follows: 
• Baseline value 
• Values at each postbaseline time point 
• Postbaseline minimum value 
• Change from baseline at each postbaseline time point 
A baseline value will be defined as the last available value collected on or prior to the 
date/time of first dose of study drug.  Change from baseline to a postbaseline visit will be 
defined as the postbaseline value minus the baseline value.  Body weight and vital signs 
measured at unscheduled visits will be included for the baseline value selection.  
In the case of multiple values in an analysis window, data will be selected for analysis as 
described in Section 3.8.3.  No formal statistical testing is planned. 
A by-participant listing of vital signs will be provided by participant ID number and time 
point in chronological order.  Body weight, height, and BMI will be included in the vital 
signs listing, if space permits.  If not, they will be provided separately. 
7.4. 
Electrocardiogram Results 
ECG data will not be presented in the CSR since ECGs will not be assessed in this study 
other than as part of the screening process for potential new participants. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 41 
7.5. 
Other Safety Measures 
7.5.1. 
Health Utilization Assessments 
Healthcare resource utilization variables include the number and duration of medical care 
encounters, including surgeries and other selected procedures (inpatient and outpatient), the 
dates and duration of hospitalization (total days or length of stay, including duration by 
wards [e.g., intensive care unit]), the number and type of diagnostic and therapeutic tests and 
procedures, and outpatient medical encounters and treatments (including physician or 
emergency department visits, tests and procedures, and medications).  Descriptive statistics 
including number of observations, mean, 95% CI on the mean, median, minimum, and 
maximum will be presented by visit for continuous variables.  For categorical variables, the 
number and proportion of participants will be presented. 
7.5.2. 
Newborn Safety Assessments 
The number and percentage of participants who experienced AEs described below will be 
provided and summarized by SOC and PT unless otherwise indicated: 
• TEAEs 
• TEAEs of Grade 3 or higher (by SOC, PT and maximum severity) 
• Serious TEAEs 
Furthermore, all AEs reported within newborns will be listed separately. 
7.6. 
Changes From Protocol-Specified Safety Analyses 
There are no deviations from the protocol-specified safety analyses. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 42 
8. 
PATIENT-REPORTED OUTCOMES 
To evaluate QoL in participants with ICP-associated pruritus treated with volixibat versus 
placebo on the basis of the following endpoints: 
• Change in 5-D Itch scale with 1-week recall from baseline to Week 3 and delivery 
• Change in Clinician Scratch Scale (CSS) from baseline to Week 3 and delivery 
• Change in EQ-5D-5L from baseline to Week 3 and delivery 
• Change in PROMIS fatigue score from baseline to Week 3 and delivery 
• Change in PROMIS sleep score from baseline to Week 3 and delivery 
• Change in Patient Impression of Severity of Itch (PIS-Itch) from baseline to Week 3 
and delivery 
• PGIC-Itch at Week 3 and delivery 
Because the PROs are administered only at baseline, Week 3, and end of treatment, the 
change from baseline will be compared between the two groups with use of rank ANCOVA 
with adjustment for baseline with the Mann-Whitney odds as the estimand.  The estimates 
and CIs can be calculated using the R package sanon (Kawaguchi and Koch 2015). 
Additionally, the difference between treatment groups in the change from baseline at Week 3 
and, separately, at delivery, will be evaluated using an ANCOVA model with fixed, 
categorical effects of treatment group, visit, and treatment group-by-visit interaction as well 
as the continuous, fixed covariates of baseline and the baseline-by-visit interaction.  LS 
means will be calculated for each treatment group in the model.  The difference between 
volixibat and placebo change from baseline in each outcome variable will be estimated, with 
the corresponding 2-sided 95% CI constructed for each visit.  Change from baseline LS 
means with standard error, 95% CI for the LS means, p-value for testing if the LS mean is 
zero, LS mean difference between treatment groups (volixibat minus placebo) with standard 
error, 95% CI for the LS mean difference, and p-value for testing if the treatment LS means 
are equal will be calculated for each visit.  The number of observations, mean, 95% CI on the 
mean, standard deviation, median, minimum, and maximum on both the observed and change 
from baseline values will also be summarized by treatment group for each visit. 
For PGIC-Itch, since the PRO is a measure of change without a defined baseline, an 
ANCOVA model will be used, but will not include fixed covariates of baseline and the 
baseline-by-visit interaction. The dependent variable will be the PGIC-Itch value. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 43 
9. 
PHARMACOKINETIC ANALYSES 
Due to poor absorption of volixibat very low systemic exposure and plasma drug levels are 
expected.  Volixibat plasma concentrations will be summarized using descriptive statistics by 
analysis visit and dose of volixibat received at the specified analysis visit. 
For maternal volixibat plasma concentration assessments:  Plasma concentration of volixibat 
near predicted maximum observed concentration (Cmax) will be obtained during the Week 1 
visit, approximately 3 hours after dosing.  Trough plasma levels of volixibat will be obtained 
during the Week 3 visit before dosing.  Contingent upon meaningful exposures of volixibat, 
PK endpoints may include but are not limited to Cmax, time to reach Cmax (Tmax), and the area 
under the plasma concentration-time curve (AUC) from time zero to the last measurable time 
point.  Actual dosing and sampling times will be used for calculation of PK parameters.  
Additional PK parameters may be calculated.  
For fetal (umbilical cord) volixibat plasma concentration assessments:  Plasma concentration 
of volixibat in the umbilical cord blood sample obtained at delivery will be collected (when 
possible) and analyzed. 
Plasma volixibat concentrations will also be presented in participants listings. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 44 
10. 
REFERENCES 
Chan ISF, Zhang Z. Test-based exact confidence intervals for the difference of two binomial 
proportions. Biometrics 1999;55:1202–9. 
Cnaan A, Laird NM, Slasor P. Using the general linear mixed model to analyse unbalanced 
repeated measures and longitudinal data. Stat Med 1997;16:2349–80. 
European Medicines Agency. Guideline on missing data in confirmatory clinical trials. 2010. 
Ge M, Durham LK, Meyer RD, et al. Covariate-adjusted difference in proportions from 
clinical trials using logistic regression and weighted risk differences. Drug Inf J 
2011;45:481–93. 
Kawaguchi A, Koch GG. Sanon: an R package for stratified analysis with nonparametric 
covariable adjustment. J Stat Softw 2015;671–37. 
Kenward MG, Roger JH. Small sample inference for fixed effects from restricted maximum 
likelihood. Biometrics 1997;53:983–97. 
Kieser M, Friede T. Simple procedures for blinded sample size adjustment that do not affect 
the type I error rate. Stat Med 2003;22:3571-81. 
Koch GG, Carr GJ, Amara IA, Stokes ME, Uryniak TJ. Categorical Data Analysis. Chapter 
13 in Berry, D.A. (ed.). Statistical Methodology in the Pharmaceutical Sciences. New York: 
Marcel Dekker, Inc., 1989:pp. 414-21. 
Little R, Rubin D. Statistical analysis with missing data. New York: John Wiley. 1987.  
Little R, Yau L. Intent-to-treat analysis for longitudinal studies with drop-outs. Biometrics 
1996;52:1324–33. 
Mallinckrodt CH, Clark WS, David SR. 2001. Accounting for dropout bias using 
mixed-effects models. J Biopharm Stat 2001;11:9–21. 
Mallinckrodt CH, Lane PW, Schnell D, Peng Y, Mancuso JP. Recommendations for the 
Primary Analysis of Continuous Endpoints in Longitudinal Clinical Trials. Drug Information 
Journal 2008;42:303–19. 
Mallinckrodt CH, Roger J, Chuang-Stein C, Molenberghs G, O'Kelly M, Ratitch B, Janssens 
M, Bunouf P. Recent developments in the prevention and treatment of missing data. Drug 
Information Journal 2013;48:68–80. 
Mann HB, Whitney DR. On a test of whether one of two random variables is stochastically 
larger than the other. The Annals of Mathematical Statistics 1947 Mar 1:50-60. 
Molenberghs G, Kenward MG. Missing data in clinical studies. New York: Wiley. 2007. 
Molenberghs G, Thijs H, Jansen I, et al. Analyzing incomplete longitudinal clinical trial data. 
Biostatistics 2004;5:445–64. 
Pocock SJ, Simon R. Sequential treatment assignment with balancing for prognostic factors 
in the controlled clinical trial. Biometrics 1975;31:103–15. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 45 
Qu Y, Zhao YD, Rahardja D (2008) Wilcoxon-Mann-Whitney test: stratify or not? J 
Biopharm Stat 18:1103-11. 
Ratitch B, O'Kelly M. Implementation of pattern-mixture models using standard SAS/STAT 
procedures. Proceedings of PharmaSUG 2011 (Pharmaceutical Industry SAS Users Group), 
SP04, Nashville.  
Ratitch B, O’Kelly M, Tosiello R. Missing data in clinical trials: from clinical assumptions to 
statistical analysis using pattern mixture models. Pharm Stat 2013;12:337–47. 
Schafer JL. Analysis of Incomplete Multivariate Data. New Yori: Chapman & Hall. 1997.  
Siddiqui O, Hung HM, O'Neill R. MMRM vs. LOCF: a comprehensive comparison based on 
simulation study and 25 NDA datasets. J Biopharm Stat 2009;19(2):227–46. 
Stokes ME, Davis CS, Koch GG. Categorical data analysis using SAS. SAS Institute. 2012 
Jul 31. 
van Elteren PH. On the combination of independent two sample tests of Wilcoxon. Bulletin 
of the International Statistical Institute 1960; 37:351–61. 
Verbeke G, Molenberghs G. Linear Mixed Models for Longitudinal Data. New York: 
Springer. 2000. 
Wilcoxon F. Individual comparisons by ranking methods. Biometrics Bulletin, 1, 80‐83. 
Reprinted in the Bobbs-Merrill Reprint Series in the Social Sciences, S-541. 1945. 
Yan X, Su XG. Stratified Wilson and Newcombe confidence intervals for multiple binomial 
proportions. Statistics in Biopharmaceutical Research 2010;2(3):329-35. 
Zink RC, Koch GG. NParCov3: a SAS/IML macro for nonparametric randomization-based 
analysis of covariance. J Stat Sotw 2012;50:1–7. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 46 
11. 
SOFTWARE 
SAS® Software Version 9.4. SAS Institute Inc., Cary, NC, USA. 
R Software Version 4.0.3 (or later). The R Foundation. Vienna, Austria. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 47 
12. 
SAP REVISION 
Revision Date 
(DD MMM YYYY) 
Section 
Summary of Revision 
Reason for Revision 
 
 
 
 
 
 
 
 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 48 
13. 
APPENDIX 1 SCHEDULE OF ACTIVITIES 
Table 7  
Schedule of Activities 
 
Visit Name 
Screeni
ng 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Week 1, 
2, 3, etc. 
Early 
Term* 
EOT/ 
Delivery 
F1 
F2 (EOS) 
*Participants who early terminate from study drug should still 
continue with weekly visits through delivery, F1, and F2. 
Day/Week (Window) 
Day 
 ‒10 to 
‒1 
0* 
Every 
7 Days 
(±1 Day) 
Until 
Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone 
Call: 
14 Days 
after 
Delivery 
(±2 Days) 
Clinic Visit: 
28 Days 
after 
Delivery 
(±3 Days) 
Some visits may be conducted as a home health or remote visit 
at the discretion of the investigator upon approval by the 
medical monitor or designee and in accordance with local and 
regional regulations. 
*Regardless of date of screening visit, baseline visit must 
occur no later than 35 weeks and 0 days gestational age. 
Administrative Procedures 
Informed consent 
X 
 
 
 
 
 
 
 
Eligibility Procedures 
Inclusion/exclusion criteria 
X 
X 
 
 
 
 
 
 
Demography 
X 
 
 
 
 
 
 
 
Prior/concomitant treatment 
X 
X 
X 
X 
X 
X 
X 
 
Medical history 
X 
X 
 
 
 
 
 
Includes menstrual and obstetric history 
Estimated gestational age 
assessment 
X 
 
 
 
 
 
 
Confirmation of eligibility based upon estimated gestational 
age required before randomization: CRL from early ultrasound 
or head circumference on ultrasound if CRL is >84 mm. 
Hepatitis and HIV screen, 
TSH 
X 
 
 
 
 
 
 
 
Dosing Procedures 
Randomization 
 
X 
 
 
 
 
 
 
Study treatment dispensing 
 
X 
X 
 
 
 
 
As needed  
Study treatment 
collection/reconciliation 
 
 
X 
X 
X 
 
 
As needed 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 49 
Visit Name 
Screeni
ng 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Week 1, 
2, 3, etc. 
Early 
Term* 
EOT/ 
Delivery 
F1 
F2 (EOS) 
*Participants who early terminate from study drug should still 
continue with weekly visits through delivery, F1, and F2. 
Day/Week (Window) 
Day 
 ‒10 to 
‒1 
0* 
Every 
7 Days 
(±1 Day) 
Until 
Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone 
Call: 
14 Days 
after 
Delivery 
(±2 Days) 
Clinic Visit: 
28 Days 
after 
Delivery 
(±3 Days) 
Some visits may be conducted as a home health or remote visit 
at the discretion of the investigator upon approval by the 
medical monitor or designee and in accordance with local and 
regional regulations. 
*Regardless of date of screening visit, baseline visit must 
occur no later than 35 weeks and 0 days gestational age. 
Efficacy Procedures 
Education and compliance 
assessment of pruritus 
assessments 
X 
X 
X 
 
 
 
 
Education regarding importance of eDiary compliance at 
screening visit; reinforcement regarding eDiary compliance at 
study visits (as needed). 
Once daily Adult ItchRO 
score assessment  
X 
X 
X 
X 
X 
 
 
Participant completes ItchRO at home on eDiary up to and 
including the day of delivery. 
Pruritus/QoL PRO 
assessments (5D itch scale, 
CSS, EQ-5D-5L, PROMIS 
SF v1.0-Fatigue 7a, PROMIS 
SF v1.0-Sleep Disturbance, 
PIS-Itch) 
 
X 
X* 
X 
X** 
 
 
Participant completes at clinic, except CSS, which the 
investigator completes at clinic. 
All PRO assessments to be completed by participant, 
including PIS-Itch and PGIC-Itch, should be collected prior to 
additional procedures at study visits. 
*At Week 3 visit only  
**For participants who terminate from study drug early, this 
does not need to be repeated. 
PGIC-Itch 
 
 
X* 
X 
X** 
 
 
Participant completes at clinic. 
*At Week 3 visit only  
**For participants who terminate from study drug early, this 
does not need to be repeated. 
Other Procedures 
Health utilization 
 
X 
 
X 
 
 
X 
 
Safety Procedures 
Drug and alcohol screen 
X 
 
 
 
 
 
 
 
Hematology panel 
X 
 
X 
X 
X 
 
X 
 
Chemistry 
X 
 
X 
X 
X 
 
X 
 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 50 
Visit Name 
Screeni
ng 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Week 1, 
2, 3, etc. 
Early 
Term* 
EOT/ 
Delivery 
F1 
F2 (EOS) 
*Participants who early terminate from study drug should still 
continue with weekly visits through delivery, F1, and F2. 
Day/Week (Window) 
Day 
 ‒10 to 
‒1 
0* 
Every 
7 Days 
(±1 Day) 
Until 
Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone 
Call: 
14 Days 
after 
Delivery 
(±2 Days) 
Clinic Visit: 
28 Days 
after 
Delivery 
(±3 Days) 
Some visits may be conducted as a home health or remote visit 
at the discretion of the investigator upon approval by the 
medical monitor or designee and in accordance with local and 
regional regulations. 
*Regardless of date of screening visit, baseline visit must 
occur no later than 35 weeks and 0 days gestational age. 
Physical examination 
X 
X 
X 
X 
X 
 
X 
Complete examination conducted at screening and F2 visits.  
A symptom-directed examination focused on changes from 
last examination conducted at other visits.  Includes 
confirmation of fetal cardiac activity via Doppler/auscultation 
at each visit while participant is pregnant. 
Height 
X 
 
 
 
 
 
 
 
Weight 
X 
X 
X 
X 
X 
 
X 
 
ECG 
X 
 
 
 
 
 
 
 
Vital signs 
X 
X 
X 
X 
X 
 
X 
 
Coagulation (PT/INR, PTT) 
X 
 
X 
X 
X 
 
X 
 
Vitamin A, D, and E levels 
 
X 
X* 
 
X 
 
X 
*Every 4 weeks, starting with Week 4 visit.  The sample 
collection tube should be protected from light. 
Urinalysis 
X 
X 
X 
X 
X 
 
X 
 
Lipid panel, glycated albumin 
X 
 
X* 
 
X 
 
X 
*Every 2 weeks, starting with Week 2 visit 
sBA 
X 
X* 
X* 
X 
X** 
 
X 
At each visit except EOT/Delivery, must be drawn in the non-
fasting state (e.g., postprandially), 30-90 minutes after start of 
a meal.  Every effort should be made to collect postprandial 
sBA levels at approximately the same time of day (morning, 
midday, or afternoon) at each visit starting with baseline, 
except for EOT/delivery.  
*At baseline and Week 3, an additional fasting sBA must be 
performed. 
**At EOT/Delivery, sBA may be performed without regard to 
last meal. 
AE review 
 
X 
X 
X 
X 
X 
X 
AEs for mother and baby to be collected and reviewed for up 
to 30 days after respective dates of hospital discharge. 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 51 
Visit Name 
Screeni
ng 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Week 1, 
2, 3, etc. 
Early 
Term* 
EOT/ 
Delivery 
F1 
F2 (EOS) 
*Participants who early terminate from study drug should still 
continue with weekly visits through delivery, F1, and F2. 
Day/Week (Window) 
Day 
 ‒10 to 
‒1 
0* 
Every 
7 Days 
(±1 Day) 
Until 
Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone 
Call: 
14 Days 
after 
Delivery 
(±2 Days) 
Clinic Visit: 
28 Days 
after 
Delivery 
(±3 Days) 
Some visits may be conducted as a home health or remote visit 
at the discretion of the investigator upon approval by the 
medical monitor or designee and in accordance with local and 
regional regulations. 
*Regardless of date of screening visit, baseline visit must 
occur no later than 35 weeks and 0 days gestational age. 
Fetal ultrasound  
X* 
X* 
X* 
 
 
 
 
*Every 4 weeks while on study treatment; first ultrasound may 
be done during screening OR baseline (both are not required) 
Antepartum fetal monitoring 
(NST/CTG or BPP) 
 
X* 
X* 
 
 
 
 
*At baseline and Week 1 visits only, and thereafter at the 
discretion of the investigator 
Perinatal outcomes 
assessment 
 
 
 
 
X 
 
 
Outcomes include 
• 
Gestational age at delivery 
• 
Mode of delivery (e.g., vaginal, operative vaginal, 
Cesarean, etc.; and iatrogenic vs. spontaneous) 
• 
Indication(s) for delivery, if iatrogenic 
• 
Apgar score at 5 minutes 
• 
Infant/placenta weight  
• 
Maternal estimated blood loss at delivery 
• 
Presence/absence of meconium staining of amniotic fluid  
• 
Neonatal diagnoses and data, including NICU data if 
applicable 
Umbilical cord sample (at 
delivery, when possible) 
 
 
 
 
X 
 
 
Umbilical artery pH should be assessed first, followed by 
volixibat pharmacokinetics.  Thereafter, sBA, total 
cholesterol, LDL cholesterol, and glucose can be assessed in 
any order. 
Genetics - maternal blood 
(optional) 
 
X 
 
 
 
 
 
Specific testing TBD.  Must confirm specific consent has been 
obtained for genetic testing 
Genetics – cord blood sample 
(optional) 
 
 
 
 
X 
 
 
Specific testing TBD.  Must confirm specific consent has been 
obtained for genetic testing. 
NICU admission  
 
 
 
 
X 
X 
X 
Collect NICU admissions diagnoses and data for the duration 
of NICU stay (i.e., follow to resolution). 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 52 
Visit Name 
Screeni
ng 
Treatment Period 
Follow-Up 
Notes 
Baseline 
Week 1, 
2, 3, etc. 
Early 
Term* 
EOT/ 
Delivery 
F1 
F2 (EOS) 
*Participants who early terminate from study drug should still 
continue with weekly visits through delivery, F1, and F2. 
Day/Week (Window) 
Day 
 ‒10 to 
‒1 
0* 
Every 
7 Days 
(±1 Day) 
Until 
Delivery 
 
Day of 
Delivery 
(+2 Days) 
Phone 
Call: 
14 Days 
after 
Delivery 
(±2 Days) 
Clinic Visit: 
28 Days 
after 
Delivery 
(±3 Days) 
Some visits may be conducted as a home health or remote visit 
at the discretion of the investigator upon approval by the 
medical monitor or designee and in accordance with local and 
regional regulations. 
*Regardless of date of screening visit, baseline visit must 
occur no later than 35 weeks and 0 days gestational age. 
Drug Levels/Biomarkers Procedures 
Volixibat concentration 
sample (maternal plasma) 
 
 
X* 
X 
X 
 
 
*At Week 1 visit, 3 hours (+/- 15 minutes) post-dose; at Week 
3 visit, ≤60 minutes pre-dose 
When feasible, maternal sample should be collected as close 
to time of actual delivery as possible. 
Drug level sampling may be discontinued in Part 2 pending 
Part 1 results 
Volixibat concentration 
sample (fetal plasma from 
umbilical cord at delivery, 
when possible) 
 
 
 
 
X 
 
 
Drug level sampling may be discontinued in Part 2 pending 
Part 1 results 
Biomarker samples 
(maternal)  
• 
C4 (fasting and 
postprandial, 30-90 min) 
• 
FGF-19 (fasting) 
• 
Autotaxin (fasting) 
• 
Progesterone sulfate  
• 
GLP-1(fasting) 
 
X* 
X* 
 
X** 
 
 
*Baseline and at Week 3 visit only  
**Random C4 only, timed with sBA draw at EOT/Delivery 
visit 
5-D Itch; Adult Itch RO; AE=adverse event; BPP=biophysical profile; C4=7α-hydroxy-cholesten-3-one; CRL=crown rump length; CSS=Clinician Scratch Scale; 
CTG=cardiotocography; eDiary=electronic diary; EOS=end of study; EOT=end of treatment; EQ-5D-5L=EuroQoL 5-Dimension 5-Level; ET=early termination; F1=follow-up 
Visit 1; F2=follow-up Visit 2; ItchRO=Itch Reported Outcome; NICU=neonatal intensive care unit; NST=nonstress test; PGIC-Itch=Patient Global Impression of Change-Itch; 
PIS-Itch=Patient Impression of Severity of Itch; PRO=patient-reported outcome; PROMIS=Patient-Reported Outcomes Measurement Information System; PT=prothrombin time; 
PTT=partial thromboplastin time; QoL=quality of life; sBA=serum bile acids; SF=short form; TBD=to be determined; TSH=thyroid-stimulating hormone. 
 
 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 53 
14. 
APPENDIX 2 ADVERSE EVENTS OF SPECIAL INTEREST 
AND CLINICAL INTEREST 
The following event is an AESI for participants in this study: 
• Symptomatic cholelithiasis 
• Threatened preterm labor 
The following events are ECIs in this study: 
• Diarrhea (CTCAE Grade ≥3) 
o MedDRA preferred terms include the following: 
 Diarrhoea 
• Abdominal pain (CTCAE Grade ≥3) 
o MedDRA preferred terms include the following: 
 Abdominal pain 
 Abdominal pain lower 
 Abdominal pain upper 
• Transaminase increases (CTCAE Grade ≥3) 
o MedDRA preferred terms include the following: 
 Alanine aminotransferase abnormal 
 Alanine aminotransferase increased 
 Aspartate aminotransferase abnormal 
 Aspartate aminotransferase increased 
 Bilirubin conjugated abnormal 
 Bilirubin conjugated increased 
 Blood bilirubin abnormal 
 Blood bilirubin increased 
 Blood bilirubin unconjugated increased 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 54 
 Liver function test abnormal 
 Liver function test increased 
 Transaminases abnormal 
 Transaminases increased 
• Fat-soluble vitamin deficiency 
o MedDRA preferred terms include the following: 
 Vitamin A decreased 
 Vitamin A abnormal 
 Vitamin A deficiency 
 Vitamin D decreased 
 Vitamin D abnormal 
 Vitamin D deficiency 
 Vitamin E decreased 
 Vitamin E abnormal 
 Vitamin E deficiency 
 Vitamin K decreased 
 Vitamin K abnormal 
 Vitamin K deficiency 
 International normalised ratio increased 
 International normalised ratio abnormal 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 55 
15. 
APPENDIX 3 SAS SAMPLE CODES 
A sample of the SAS code for sensitivity analysis using the copy-reference MI method is 
provided as below: 
 
/*Generate transpose of adcf - wide format before Step 1*/ 
/*---- Generates 10 imputed data sets based on original (non-transformed) 
data----*/ 
/*Step 1: Achieve Monotone Missing Data Pattern */ 
 PROC MI DATA=&DATA SEED=14823 NIMPUTE=10 OUT=MONO; 
 /* Use numeric TRT01PN */ 
 VAR BASE AVAL1 AVAL2 AVAL3; /*Refer to AVAL at Visits 5, 6, and 7*/ 
 MCMC IMPUTE=MONOTONE NBITER=5000 NITER =5000; 
 BY TRT01PN; 
 run; 
 
/*Step 2: Achieve Control-Based Copy-Reference Imputation */ 
 PROC MI DATA=MONO SEED=14823 NIMPUTE=1 OUT=OUTM1; 
 CLASS TRT01PN; 
 By _IMPUTATION_; 
 VAR TRT01PN BASE AVAL1 AVAL2 AVAL3; 
 MONOTONE REG (AVAL2 AVAL3); 
 MNAR MODEL (AVAL1 AVAL2 AVAL3/ MODELOBS = (TRT01PN = ‘0’)); 
 /*Control=Placebo*/ 
 RUN; 
 PROC SORT DATA =OUTM1; BY _IMPUTATION_ TRT01PN USUBJID LBASE; RUN; 
 /*Generate transpose of OUTM1 - skinny format before Step 3*/ 
 
/*Step 3: Run MMRM Analysis on Imputed Data */ 
PROC MIXED DATA=OUTM1 METHOD=REML; 
 BY _IMPUTATION_; 
CLASS TRT01PN USUBJID AVISITN COUNTRY SEX; 
MODEL CHG = TRT01PN AVISITN COUNTRY SEX TRT01PN*AVISITN BASE / DDFM=KR; 
REPEATED / SUBJECT=USUBJID (TRT01PN) TYPE=UN; 
LSMEANS TRT01PN*AVISITN / CL DIFF PDIFF;  
 ESTIMATE 'TRT S - P AT WEEK 24' TRT01PN -1 1 
 TRT01PN*AVISITN 0 0 -1 0 0 1 / CL LOWER LOWERTAILED; 
 ODS OUTPUT PARAMETERESTIMATES=PESTIMATES; 
RUN; 
 
/*Step 4: Combining estimates from each imputed data set */ 
/*First, sort the data of estimates by visit (variable “LABEL”) */ 
PROC MIANALYZE DATA=PESTIMATES; 
 MODELEFFECTS ESTIMATE; 
 STDERR STDERR; 
 BY LABEL; 
 ODS OUTPUT PARAMETERESTIMATES= MIPARM; 
RUN; 
 
 
A sample of the SAS code for sensitivity analysis using the tipping-point approach is 
provided as below: 
 
/*---------------------------------------------------------*/ 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 56 
/*--- Performs multiple imputation analysis ---*/ 
/*--- for specified shift parameters: ---*/ 
/*--- data= input data set ---*/ 
/*--- smin= min shift parameter ---*/ 
/*--- smax= max shift parameter ---*/ 
/*--- sinc= increment of the shift parameter ---*/ 
/*--- outparms= output parameters ---*/ 
/*---------------------------------------------------------*/ 
%MACRO MIPARMS( DATA=, SMIN=, SMAX=, SINC=, OUTPARMS=); 
DATA &OUTPARMS; 
 SET _NULL_; 
RUN; 
/*------------ # of shift values ------------*/ 
%LET NCASE= %SYSEVALF( (&SMAX-&SMIN)/&SINC, CEIL ); 
/*---- Multiple imputation analysis for each shift ----*/ 
%DO JC=0 %TO &NCASE; 
 %LET SJ= %SYSEVALF( &SMIN + &JC * &SINC); 
 
 /*---- Generates 10 imputed data sets ----*/ 
 
/*Step 1: Achieve Monotone Missing Data Pattern */ 
 
 PROC MI DATA=&DATA SEED=14823 NIMPUTE=10 OUT=MONO; 
 ** Use numeric TRT01PN ; 
 VAR BASE AVAL1 AVAL2 AVAL3; /*Refer to AVAL at Visits 5, 6, and 7*/ 
 MCMC IMPUTE=MONOTONE NBITER=5000 NITER =5000; 
 BY TRT01PN; 
 run; 
 
/*Step 2: Impute all visits under MAR first, then apply delta adjustments 
at each visit*/ 
 
 PROC MI DATA= OUTM1 SEED=14823 NIMPUTE=1 OUT=OUTM2; 
 CLASS TRT01PN; 
 BY _IMPUTATION_; 
 VAR TRT01PN BASE AVAL1 AVAL2 AVAL3; 
 MONOTONE REG (AVAL2 AVAL3); 
 MNAR ADJUST( AVAL1 / SHIFT=&SJ ADJUSTOBS=(TRT01PN ='1') ); 
 MNAR ADJUST( AVAL2 / SHIFT=&SJ ADJUSTOBS=(TRT01PN ='1') ); 
 MNAR ADJUST( AVAL3 / SHIFT=&SJ ADJUSTOBS=(TRT01PN ='1') ); 
 RUN; 
 PROC SORT DATA =OUTM1; BY _IMPUTATION_ TRT01PN USUBJID BASE; RUN; 
 
/*Generate transpose of OUTM2 - skinny format before Step 3*/ 
 
/*Step 3: Run MMRM Analysis on Imputed Data */ 
 
PROC MIXED DATA=OUTM2 METHOD=REML; 
 BY _IMPUTATION_; 
CLASS TRT01PN USUBJID AVISITN COUNTRY SEX; 
MODEL CHG = TRT01PN AVISITN COUNTRY SEX TRT01PN*AVISITN BASE / 
DDFM=KR; 
REPEATED / SUBJECT=USUBJID (TRT01PN) TYPE=UN; 
LSMEANS TRT01PN*AVISITN / CL DIFF PDIFF; 
  ESTIMATE 'TRT S - P AT WEEK 24' TRT01PN -1 1 
 TRT01PN*AVISITN 0 0 -1 0 0 1 / CL LOWER LOWERTAILED; 
 ODS OUTPUT PARAMETERESTIMATES=PESTIMATES; 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 57 
 RUN; 
 
 /*First, sort the data of estimates by visit (variable “LABEL”) */ 
 
 PROC SORT DATA=PESTIMATES; BY LABEL; RUN: 
 
 /*Step 4: Combining estimates from each imputed data set */ 
 
PROC MIANALYZE DATA=PESTIMATES; 
 MODELEFFECTS ESTIMATE; 
 STDERR STDERR; 
 BY LABEL; 
 ODS OUTPUT PARAMETERESTIMATES=MIPARM; 
RUN; 
DATA MIPARM; 
SET MIPARM; 
 SHIFT= &SJ; 
RUN; 
 
/*----- Output multiple imputation results ----*/ 
 
DATA &OUTPARMS; 
 SET &OUTPARMS MIPARM; 
RUN; 
%END; 
%MEND MIPARMS; 
 
/*Assume that the tipping point for the shift parameter that reverses the 
study conclusion is between 0 and 100. The following statement performs 
multiple imputation analysis for each of the shift parameters 
0,10,20,30,…,100.*/ 
 
ODS LISTING CLOSE; 
%MIPARMS(DATA=XXXX, SMIN=0, SMAX=100, SINC=10, OUTPARMS=PARMS1); 
 
/* Step 5: Finding Tipping Point for Shift Parameter between 0 and 100 
such that p-value is less than 0.05, below is an example for a tipping 
point for the shift parameter between 40 and 50. 
For a two-sided Type I error level of 0.05, the tipping point for the 
shift parameter is greater than 40. The following statement performs 
multiple imputation analysis for shift parameters 40, 41, …, 50*/ 
 
%MIPARMS(DATA=XXXX, SMIN=40, SMAX=50, SINC=1, OUTPARMS=PARM2); 
/*The following statements display the p-values that are associated with 
the shift parameters.*/ 
PROC PRINT LABEL DATA=PARM2; 
 VAR SHIFT PROBT; 
 TITLE 'P-VALUES FOR SHIFT PARAMETERS'; 
 LABEL PROBT='PR > |T|'; 
 FORMAT PROBT 8.4; 
RUN; 
 
 
A sample of the SAS code for van Elteren test is provided as below: 
 
 


VLX-401 
Statistical Analysis Plan 
 
CONFIDENTIAL 
Page 58 
proc npar1way data=adeff ; 
  strata BLGSTAGE BLITCHRO BLGDIAB; 
  class trt01p; 
  var chg; 
run;