Clinical trial NCT03931941
Conditions: Clostridium Difficile Infection Infection Communicable Diseases
Keywords: C. Difficile Diarrhea Clostridium Difficile CDI FMT Fecal Microbiota Transplant Microbiota Restoration Therapy Diarrhea Microbial Suspension Fecal Transplant C Difficile Colitis Clostridium Difficile Associated Diarrhea C diff diarrhea C Difficile C diff
Sponsor: Rebiotix Inc.
Start date: 2019-07-30; Completion date: 2023-07-21
Enrollment: 793 participants; Allocation: NA; Intervention model: SINGLE_GROUP

Brief summary:
This is a prospective, multicenter, open-label Phase 3 study of a microbiota suspension of intestinal microbes. Patients who have had at least one recurrence of CDI after a primary episode and have completed at least one round of standard-of-care oral antibiotic therapy or have had at least two episodes of severe CDI resulting in hospitalization may be eligible for the study. Subjects may receive a second RBX2660 enema if they are deemed treatment failures following the initial enema per the protocol-specified treatment failure definition.

Detailed description:
This is a prospective, multicenter, open-label Phase 3 study of a microbiota suspension of intestinal microbes. The primary assessments for this study are (i) safety via assessment of treatment-emergent adverse events and (ii) efficacy of RBX2660 preventing recurrent episodes of CDI measured at 8 weeks after treatment. Follow-up office visits occur at 1 week and 8 weeks after completing the initial study treatment. Telephone assessments occur at 4 weeks, and 4 and 6 months after the study. Patients who have had at least one recurrence of CDI after a primary episode and have completed at least one round of standard-of-care oral antibiotic therapy or have had at least two episodes of severe CDI resulting in hospitalization may be eligible for the study. Subjects may receive a second RBX2660 enema if they are deemed treatment failures following the initial enema per the protocol-specified treatment failure definition.

Arms: arm 1: RBX2660 is an enema of a microbiota suspension
Interventions: intervention 1: RBX2660
Intervention descriptions: intervention 1: RBX2660 is a microbiota suspension administered as an enema

Protocol documents:
Prot_000.pdf: 
Rebiotix Inc.   
RBX2660 Microbiota Suspension 
 Open-Label Study Protocol 2019-01 
Version: 7.0; 26MAY2022 
 CONFIDENTIAL 
 Page 1 of 85 
A  Phase 3 Open-Label Clinical Study to Evaluate the Safety and Tolerability of 
Rebiotix RBX2660 (microbiota suspension) in Subjects with Recurrent 
Clostridium difficile Infection 
NCT03931941
Sponsor: 
Rebiotix Inc. 
2660 Patton Road 
Roseville, MN 55113 USA 
P:  1-651-705-8770 
Study Product:    RBX2660 (microbiota suspension) 
Protocol #:   2019-01 
Version #: 
7.0; 26MAY2022 
This document contains confidential information belonging to Rebiotix Inc. the study 
sponsor.  Except as otherwise agreed to in writing by the sponsor, by accepting or 
reviewing this document, you agree to hold this information in confidence and not copy 
or disclose it to others or use it for unauthorized purposes.  In the event of any actual or 
suspected breach of this obligation, Rebiotix must be promptly notified. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 2 of 85 
 
1. Revision History and Sponsor Statement 
Version 
Date 
Reason 
1.0 
14Jan2019 
Initial Release 
2.0 
12Apr2019 
Added 4-week assessment for second enema follow-up and clarified data 
collection elements. 
3.0 
22Jul2019 
This protocol version is for submission to Health Canada and Canadian sites 
to address a request for incorporation of screening and testing procedures 
related to Health Canada’s Safety Alert for Fecal Microbiota Therapy. This 
protocol version was not submitted to the FDA or US study sites. 
4.0 
06Sep2019 
Aligned medical record documentation of recurrent CDI with current 
medical practice, and incorporation of the protocol clarification letter 
identifying Baseline stool sample testing of Extended spectrum beta-
lactamase (ESBL)-producing Enterobacteriaceae.  
5.0 
15OCT2020 
Increased the maximum number of subjects to be treated with RBX2660 to 
500.  This allows continued enrollment, open-label access, and prospective 
data collection in a broad patient population. Updated supporting clinical 
data to include final results from Phase 2 clinical studies of RBX2660.  
6.0 
08Dec2021 
Increased the maximum number of subjects to be treated with RBX2660 to 
600.  
Added final study results for Protocols 2017-01 and 2019-02 
7.0 
26MAY2022 
Increased the maximum number of subjects to be treated with RBX2660 to 
750. 
Clarified Other Endpoints analysis time points for Vancomycin Resistant 
Enterococcus  
Sponsor Statement:  
This protocol has been written in accordance with ICH E6 and the Rebiotix procedure governing 
clinical study protocol development.  
 
 
   
 
 
                                 Date (DD/MMM/YYYY) 
 
Rebiotix, Inc. 
 
 
Type text here


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 3 of 85 
 
2. Investigator’s Acknowledgement of the Clinical Study Protocol 
Study Name:   A Phase 3 Open-Label Clinical Study to Evaluate the Safety and Tolerability 
of Rebiotix RBX2660 (microbiota suspension) in Subjects with Recurrent Clostridium difficile 
Infection 
Version Number:  7.0 
Version Date: 26MAY2022 
Investigational Site: 
 
 
I have read this protocol and agree that it contains all necessary details for carrying out this 
study. I will conduct the study as outlined herein and will complete the study within the time-
frame designated. 
 
I will provide copies of the protocol and all pertinent information to the individuals responsible 
to me who assist in the conduct of this study.  I will discuss this material with them to ensure that 
they are fully informed regarding the conduct of the study and the study product prior to their 
conducting any study-specific activities. 
 
 
Accepted by: 
 
 
Principal Investigator’s Signature 
 
 
 
 
Date (DD/MMM/YYYY) 
 
 
Principal Investigator’s Name  
 
 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 4 of 85 
 
 
Table of Contents 
1. 
Revision History and Sponsor Statement........................................................................... 2 
2. 
Investigator’s Acknowledgement of the Clinical Study Protocol ........................................ 3 
3. 
List of Abbreviations and Acronyms................................................................................. 8 
4. 
Study Synopsis ...............................................................................................................10 
5. 
Background ....................................................................................................................18 
5.1. 
Investigational Agent................................................................................................19 
5.2. 
Preclinical Data ........................................................................................................19 
5.3. 
Clinical Data to Date ................................................................................................20 
5.3.1. Phase 2 Study Protocol 2013-001 Final Data ..........................................................20 
5.3.2. Phase 2 Study Protocol 2014-01 Final Study Data ..................................................23 
5.3.3. Phase 2 Study Protocol 2015-01 Final Study Data ..................................................24 
5.3.4. Phase 3 Study Protocol 2017-01 Final Study Data ..................................................25 
5.3.5. Retrospective Study Protocol 2019-02 Final Study Data .........................................27 
5.4. 
Treatment Rationale and Risk/Benefit .......................................................................28 
6. 
Study Objectives and Endpoints ......................................................................................29 
6.1. 
Primary Objective.....................................................................................................29 
6.2. 
Secondary Objectives ...............................................................................................29 
6.3. 
Other Objectives.......................................................................................................29 
6.4. 
Primary Endpoint .....................................................................................................29 
6.5. 
Secondary Endpoints ................................................................................................29 
6.6. 
Safety Endpoints ......................................................................................................29 
6.7. 
Other Endpoints .......................................................................................................30 
7. 
Study Design ..................................................................................................................30 
7.1. 
Study Purpose ..........................................................................................................30 
7.2. 
General Study Design ...............................................................................................30 
7.3. 
Study Definitions......................................................................................................32 
7.3.1. Control of symptoms during antibiotic use .............................................................32 
7.3.2. Indeterminate Treatment Outcome .........................................................................33 
7.3.3. Medications...........................................................................................................33 
7.3.3.1. 
Prior Medications...........................................................................................33 
7.3.3.2. 
Concomitant Medications ...............................................................................33 
7.3.3.3. 
Prohibited Medications...................................................................................33 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 5 of 85 
 
7.3.4. Recurrent CDI .......................................................................................................33 
7.3.4.1. 
Recurrent CDI for Study Entry ........................................................................33 
7.3.4.2. 
Recurrent CDI On-study .................................................................................34 
7.3.5. Sustained Clinical Response ..................................................................................34 
7.3.6. Treatment Failure ..................................................................................................34 
7.3.7. Treatment Success .................................................................................................34 
7.4. 
Determination of Treatment Success/Failure..............................................................34 
7.5. 
Management of Treatment Failure.............................................................................35 
7.6. 
Medical Monitor.......................................................................................................35 
7.7. 
Data and Safety Monitoring Board ............................................................................35 
7.8. 
Endpoint Adjudication Committee ............................................................................36 
7.9. 
Bias .........................................................................................................................36 
8. 
Subject Selection and Withdrawal ...................................................................................36 
8.1. 
Inclusion Criteria ......................................................................................................36 
8.2. 
Exclusion Criteria.....................................................................................................37 
8.3. 
Subject Recruitment and Screening ...........................................................................37 
9. 
Investigational Product....................................................................................................38 
9.1. 
RBX2660 Description ..............................................................................................38 
9.2. 
Rebiotix Kit Description ...........................................................................................38 
9.3. 
Treatment Regimen ..................................................................................................38 
9.4. 
Subject Follow-up Requirements...............................................................................39 
9.5. 
Concomitant Therapy ...............................................................................................39 
9.6. 
Preparation of Investigational Product .......................................................................39 
9.7. 
Packaging.................................................................................................................40 
9.8. 
Ordering, Receipt and Storage, Dispensing, Returning, and Tracking Investigational 
Product...............................................................................................................................40 
9.8.1. Ordering Investigational Product ............................................................................40 
9.8.2. Receipt and Storage of Investigational Product .......................................................40 
9.8.3. Dispensing and Administering Investigational Product ...........................................40 
9.8.4. Returning IP ..........................................................................................................41 
9.8.5. Product Accountability and Tracking .....................................................................41 
10. 
Study Procedures..........................................................................................................41 
10.1. General Information .................................................................................................41 
10.2. Informed Consent .....................................................................................................43 
10.3. Subject Diary ...........................................................................................................43 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 6 of 85 
 
10.4. Optional Stool Samples for Additional Testing by Rebiotix .......................................43 
10.5. Screening Visit .........................................................................................................44 
10.6. Randomization .........................................................................................................45 
10.7. Order IP/Study Drug.................................................................................................45 
10.8. Baseline Visit and Study Treatment Administration ...................................................45 
10.9. 1-week In-Office Visit ..............................................................................................48 
10.10. 4-week Telephone Assessment..................................................................................48 
10.11. 8-week In-Office Visit ..............................................................................................49 
10.12. 4- and 6- Month Telephone Assessments ...................................................................49 
10.13. Unscheduled Possible Recurrence Visit .....................................................................50 
10.14. Second RBX2660 Treatment.....................................................................................51 
10.14.1. 
1-week, 4-weeks, 8-weeks, 6-month Telephone Assessment ............................53 
10.15. Study Exit ................................................................................................................53 
10.16. Subject Withdrawal or Termination...........................................................................54 
11. 
Assessment of Safety....................................................................................................55 
11.1. Adverse Event Management .....................................................................................55 
11.2. AE Definitions .........................................................................................................56 
11.3. Anticipated Adverse Events ......................................................................................57 
11.4. Solicited Events........................................................................................................58 
11.5. Preexisting Condition ...............................................................................................58 
11.6. Serious Adverse Event Reporting – Procedures for Investigators ................................59 
11.6.1. 
Initial Reports.................................................................................................59 
11.6.2. 
Follow-Up Reports .........................................................................................59 
11.7. Grading Event Severity.............................................................................................59 
11.8. Causality ..................................................................................................................63 
11.9. Pregnancy Reporting ................................................................................................64 
11.10. Medical Monitor.......................................................................................................64 
11.11. Data and Safety Monitoring Board (DSMB) ..............................................................64 
11.12. Endpoint Adjudication Committee (EAC) .................................................................65 
11.13. Study Stopping Rules for Safety................................................................................65 
11.14. Sponsor Reporting of Adverse Events .......................................................................66 
11.14.1. 
Timeline for Reporting Requirements..............................................................66 
11.14.2. 
Additional Reporting Requirements ................................................................67 
11.14.3. 
Reporting AEs to FDA and Health Canada ......................................................67 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 7 of 85 
 
12. 
Sample Size and Statistical Considerations....................................................................67 
12.1. Sample Size .............................................................................................................67 
12.2. Assessment of Safety and Tolerability .......................................................................67 
12.3. Assessment of Efficacy, Secondary Objectives ..........................................................68 
12.3.1. 
Analysis Population definitions .......................................................................68 
12.3.1.1. 
Safety Population ........................................................................................68 
12.3.1.2. 
Intent-to-Treat Population...........................................................................68 
12.3.1.3. 
Modified Intent-to-Treat Population ............................................................69 
12.3.1.4. 
Per-Protocol Population .............................................................................69 
13. 
Study Administration ...................................................................................................69 
13.1. Institutional Review Board / Research Ethics Board Approval ...................................69 
13.1.1. 
US Sites .........................................................................................................70 
13.1.2. 
Canadian Sites................................................................................................70 
13.2. Form 1572 and Financial Disclosure .........................................................................70 
13.2.1. 
Canadian Sites:  Qualified Investigator Undertaking Form ...............................71 
13.3. Subject Confidentiality .............................................................................................71 
13.4. Study Oversight........................................................................................................71 
13.5. Study Site Qualification ............................................................................................72 
13.6. Investigator / Site Training........................................................................................72 
13.7. Data Management.....................................................................................................72 
13.8. Monitoring ...............................................................................................................73 
13.9. Direct Access to Source Data/Documents ..................................................................73 
13.10. Investigator Responsibilities .....................................................................................73 
13.11. Investigator Records .................................................................................................74 
13.12. Investigator Reports..................................................................................................75 
13.13. Study Site Termination .............................................................................................75 
13.14. Protocol Amendments ..............................................................................................75 
13.15. Protocol Deviations ..................................................................................................76 
13.16. Inspection/Auditing ..................................................................................................76 
14. 
Publication Plan ...........................................................................................................76 
15. 
References ...................................................................................................................77 
16. 
Comorbidity Index Variables ........................................................................................78 
17. 
Cdiff 32 Health-Related Quality of Life Questionnaire ..................................................80 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 8 of 85 
 
3. List of Abbreviations and Acronyms 
AE – adverse event 
AIDS – Acquired Immunodeficiency Syndrome 
ALT – alanine aminotransferase 
AST – aspartate transaminase 
BUN – blood urea nitrogen 
CBC – complete blood count 
CDAD – Clostridium difficile-associated diarrhea 
CDI – Clostridium difficile infection 
CFR – Code of Federal Regulations 
CMP – comprehensive metabolic panel 
CRE – Carbapenem-resistant Enterobacteriaceae  
CRP – C-reactive protein 
DSMB – Data and Safety Monitoring Board 
EAC – Endpoint Adjudication Committee 
eCRF – electronic case report form 
ESBL – Extended spectrum beta-lactamase  
FDA – Food and Drug Administration 
FMT – Fecal microbiota transplant 
FT – fecal transplant 
GCPs – Good Clinical Practices 
GDH – glutamate dehydrogenase  
HIV – human immunodeficiency virus 
IBD – inflammatory bowel disease 
IBS – irritable bowel syndrome 
ICF – informed consent form 
ICH – International Council on Harmonisation 
ICU – intensive care unit 
IFU – Instructions for Use 
IgG – Immunoglobulin  
IP – Investigational product 
IRB – Investigational Review Board 
ISF – Investigator Site File 
ITT – Intent-to-Treat 
IV – intravenous  
IVIG – intravenous immunoglobulin 
MDRO – multi-drug resistant organism 
mL – milliliter 
MRSA – Methicillin-resistant Staphylococcus aureus  
NA – not applicable 
OTC – Over the counter 
PAL – Product Accountability Log 
PP – Per Protocol 
rCDI – Recurrent Clostridium diffcile infection 
REB – Research Ethics Board 
SAE – serious adverse event 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 9 of 85 
 
 
SAP – Statistical Analysis Plan 
VRE – vancomycin-resistant enterococci 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 10 of 85 
 
4. Study Synopsis 
 
Title 
A Phase 3 Open-Label Clinical Study to Evaluate the Safety and 
Tolerability of Rebiotix RBX2660 (microbiota suspension) in Subjects 
with Recurrent Clostridium difficile Infection.  
Investigational 
Product  
RBX2660 (microbiota suspension).   
Indication for 
Use 
RBX2660 is being studied for the prevention of recurrent Clostridium 
difficile infection (CDI) in individuals with prior recurrent CDI infection 
resolved following antibiotic treatment. 
Study Purpose 
The purpose of this study is to evaluate the safety and tolerability of 
RBX2660 in subjects with recurrent CDI who have had prior recurrent 
CDI that was resolved with antibiotic treatment. 
Definition of 
Recurrent CDI 
for Study Entry 
To be considered for enrollment, a subject must have medical record 
documentation of: 
a) a current diagnosis or history of recurrent CDI as determined by 
the treating physician,  
b) or has had at least two separate episodes of severe CDI resulting in 
hospitalization. 
Definition of CDI 
Diarrhea On-
Study 
The definition of CDI diarrhea for use in enrolled subjects throughout the 
study (Baseline visit through month 6 visit) includes: 
1. The passage of three or more unformed/loose stools (i.e., Bristol 
Stool Scale type 6-7) in 24 or fewer consecutive hours for at least 
two consecutive days; 
2. and a positive stool test for the presence of C. difficile as 
determined by the central laboratory. 
Objectives 
Primary Objective:  To evaluate the safety and tolerability of RBX2660 in 
subjects with recurrent CDI. 
Secondary Objectives:  
1. To evaluate the efficacy of RBX2660 in preventing recurrent 
episodes of CDI through 8 weeks after treatment. 
2. To evaluate the sustained clinical response rate of RBX2660 after 
treatment. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 11 of 85 
 
Endpoints 
Primary Endpoint:   Number of subjects with investigational product- 
and/or enema-related treatment-emergent adverse events (TEAEs). 
Secondary Endpoints:     
1. Recurrence of CDI through 8 weeks after treatment.  
2. Loss of sustained clinical response through 6 months after 
treatment. 
Safety Endpoints: 
1. Number of adverse events per subject 
2. Timing of attributable TEAEs 
3. Duration of TEAEs 
4. Relatedness of TEAEs 
5. Severity of TEAEs 
6. Causality of TEAEs to investigational product (IP), enema, C. 
difficile or prior condition  
7. Number of each of the following CDI-related TEAEs through 8 
weeks post-treatment: death, septic shock, toxic megacolon, 
colonic perforation, emergency colectomy, and ICU admission.  
8. Onset of new chronic conditions relative to RBX2660 treatment 
administration.  
Study Design 
 
 
 
 
 
 
 
 
 
 
 
 
This is an open-label Phase 3 study to evaluate the safety and tolerability 
of RBX2660 in subjects with recurrent CDI.   
Up to 750 subjects may be treated in this study.  Consented subjects who 
meet all eligibility criteria are intended to be treated.  Consented subjects 
who do not meet the eligibility criteria will be considered screen failures 
and will not count towards the total number of subjects treated.    
Potential subjects are expected to already be taking or have just been 
prescribed antibiotics to control recurrent CDI symptoms at the time of 
enrollment (Screening visit) per the investigator’s standard of care.   
Patients who have already completed their prescribed course of antibiotics 
to treat recurrent CDI are not eligible for enrollment (Screening visit) 
unless they have another recurrence that is treated with antibiotics.   
Once the Screening visit is complete, in order to proceed to the Baseline 
Enema Administration:  
1. Subject must meet all the inclusion and none of the exclusion 
criteria 
2. Antibiotics will have been administered prior to the washout 
period 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 12 of 85 
 
3. CDI symptoms must be under control leading into the antibiotic 
washout period 
Control of CDI symptoms is defined as no longer meeting the 
symptomatic criteria for CDI diarrhea which is the passage of three or 
more unformed/loose (i.e., Bristol Stool Scale type 6-7) stools in 24 or 
fewer consecutive hours while taking antibiotics for the two consecutive 
days prior to the washout period.  Thus, at a minimum the Subject Diary 
which is started at the Screening visit must show that symptoms are under 
control the two days prior to the washout period in order for the subject to 
receive the enema administration.   
The Baseline visit and administration of study treatment (enema 
administration) is to be completed as soon as possible, but no later than 21 
days after the Screening visit.   A minimum 24hr to a maximum of 72hr 
antibiotic washout period is required prior to administration of the study 
treatment.    
In-office study follow-up visits occur at weeks 1 and 8 after completing 
the Baseline visit.  Telephone assessments occur at week 4 and at months 
4 and 6 after the Baseline visit.  Subjects are required to keep a detailed 
diary to assess for solicited events from the date of Screening visit to the 
1-week follow-up visit.  The diary will be collected and reviewed at the 
Baseline visit prior to enema administration.  The subject will continue to 
complete the diary for one week following the Baseline visit (enema 
administration) and it will be collected and reviewed at the 1-week 
follow-up visit.  
Subjects may receive a second RBX2660 enema if they are deemed 
failures following treatment per the protocol-specified treatment failure 
definition.  This second enema is to be administered within 21 calendar 
days of failure determination.  If a subject receives a second RBX2660 
enema, follow-up is completed via telephone assessments at 1-week, 4-
weeks, 8-weeks, and 6-months after completing the second enema.  A 
final analysis and report will be completed once the last subject has 
completed the 6-month follow-up visit for their study treatment, including 
6-month follow-up after a second RBX2660 study treatment, if applicable.  
Definition of 
Treatment 
Success 
Treatment success is defined as:  
• The absence of CDI diarrhea for 8 weeks after completing a study 
treatment.   


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 13 of 85 
 
Definition of 
Sustained 
Clinical Response 
Sustained Clinical Response is defined as: 
• Treatment success of the presenting CDI recurrence and no new 
CDI episodes for greater than 8 weeks through 6 months after 
completing a study treatment.        
Definition of 
Treatment 
Failure (CDI 
recurrence) 
Treatment failure (CDI recurrence) is defined as:  
• The presence of CDI diarrhea within 8 weeks of administration of 
a study enema, which includes a positive stool test for C. difficile 
as determined by the central laboratory.  
If a CDI recurrence is suspected, an in-office visit is required, and the 
subject must provide a fresh stool sample.  A stool sample is to be sent to 
the central laboratory for analysis.  In the case of suspected treatment 
failure where there is an immediate concern for subject safety, including 
the potential for serious adverse events, a test may be conducted at the site 
or other laboratory known to the site in addition to sending a sample to 
the central laboratory for testing.  The central laboratory’s testing result 
will be used for defining treatment failures, instead of the other 
laboratory’s result. 
Management of 
Treatment 
Failures 
Following treatment, subjects meeting the protocol definition of treatment 
failure may be scheduled for administration of a second RBX2660 enema 
within 21 calendar days of failure determination.  In order to receive the 
second RBX2660 enema, the site must provide documentation of meeting 
all treatment failure criteria as defined by the protocol.   
The use of antibiotics prior to a second RBX2660 enema is at the 
discretion of the investigator.  If antibiotics are given to control 
symptoms, a 24-72 hour washout period prior to administration of a 
second RBX2660 enema is required.  If elected, the second enema is to be 
administered within 21 calendar days of failure determination.   
If a subject receives a second RBX2660 enema, follow-up is completed 
via telephone assessments at 1-week, 4-weeks, 8-weeks and 6-months 
after the second RBX2660 treatment.   
Treatment failures who do not receive a second RBX2660 enema will 
continue to follow their original schedule of assessments through 6-month 
follow-up.  
Concomitant 
Therapy 
The subject must agree to not take any oral vancomycin, metronidazole, 
fidaxomicin, rifaximin, nitazoxanide, bezlotoxumab, or intravenous 
immunoglobulin (IVIG) through the 8-week follow-up assessment unless 
newly prescribed by a treating investigator during the course of the study 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 14 of 85 
 
as a result of a recurrent CDI diagnosis.  Use of IVIG for treatment of a 
non-CDI indication is allowed.   
Determination of 
Success/Failure: 
(Investigator and 
EAC) 
The site investigator will make the initial determination of success or 
failure based on the pre-defined study definitions.  The site investigator’s 
assessment will then be provided to the Endpoint Adjudication Committee 
(EAC) for independent adjudication of treatment success or failure that 
will be utilized for study analysis and reporting purposes.   
Medical Monitor  
The Medical Monitor provides review of serious adverse events to assess 
accuracy of the reporting as related to seriousness and causality, and 
periodic review of adverse events for trends.  The Medical Monitor’s 
review will be provided to the Data and Safety Monitoring Board 
(DSMB) for analysis purposes and as applicable for the proper 
adjudication of potential study stopping rules.  
Data and Safety 
Monitoring 
Board (DSMB) 
The DSMB will review safety data for trends and may review safety 
analysis and the final analysis.  Details regarding DSMB responsibilities 
related to analysis oversight, data reporting, and timing of meetings will 
be provided in the DSMB Charter. 
Sample Size  
The purpose of this study is to assess the safety and tolerability of 
RBX2660 in a recurrent CDI population that is broader and more 
inclusive than that included in prior studies using RBX2660. In order to 
continue to collect prospective safety information and allow open-label 
treatment access to a broad population of patients, up to 750 subjects will 
be treated with RBX2660.  
Subjects who have signed informed consent forms but do not meet all 
eligibility criteria will be considered screen failures.  Subjects who 
withdraw for any reason prior to administration of the enema will be 
replaced without counting toward the sample size treatment cap of 750 
subjects.   
Statistical 
Considerations 
 
The primary safety analysis will be performed on all subjects exposed to 
RBX2660 and will include descriptive statistics.  Additional sub-analyses 
of safety data may be performed on sub-populations.  Efficacy analyses 
will be performed on pre-defined analysis populations including Intent-to-
Treat (ITT) and modified Intent-to-Treat (mITT).     
A final analysis of safety and efficacy results will be analyzed and 
reported in a final report after the last subject has completed the 6-month 
follow-up visit for their study treatment, including 6-month follow-up 
after a second RBX2660 study treatment, if applicable.   


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 15 of 85 
 
Study Stopping 
Rules 
The DSMB will determine whether enrollment will be paused, the study 
terminated, or other action taken based on their assessment that:  
• There is probable cause that the IP or enema procedure (e.g., due 
to transfer from an RBX2660 donor) contributed to a new 
pathogenic intestinal infection in the stool of any subject; or 
• Any events of major significance such as death or other serious 
outcome for which a causal connection with the IP is plausible and 
represents an excess of the important adverse event(s). 
In the event that one of the preceding rules appears to be met based on site 
reported data and/or Medical Monitor review, the Rebiotix Operations 
Department will review the donor history and batch processing/release 
records for the product unit(s) administered in these cases.  A report of the 
review will be forwarded to the DSMB Chair for review.  If probable 
cause is suspected, the DSMB Chair will convene the entire DSMB for 
event review.   
Upon the DSMB’s determination of action, the Chair will notify Rebiotix, 
who will notify the study sites.  If enrollment is stopped, Rebiotix and the 
study sites will assess for the occurrence of similar events and evaluate IP 
and study records for possible root cause(s).  Enrollment may be re-started 
upon further review and approval from the DSMB.  As appropriate, the 
DSMB may recommend study termination or measures short of 
termination with the objective of reducing the risk of adverse events.  
Details regarding DSMB responsibilities will be provided in the DSMB 
Charter. 
Inclusion 
Criteria 
1. ≥ 18 years old.  
2. Medical record documentation of either:  a) a current diagnosis or 
history of recurrent CDI as determined by the treating physician, b) 
or has had at least two episodes of severe CDI resulting in 
hospitalization. 
3. Is currently taking or was just prescribed antibiotics to control CDI 
related diarrhea at the time of enrollment.  Note: Subject’s CDI 
diarrhea must be controlled (<3 unformed/loose stools/day, i.e., 
Bristol Stool Scale type 6-7, for the two consecutive days prior to the 
washout period) while taking antibiotics during screening. 
4. Willing and able to have an enema(s). 
5. Willing and able to complete the stool and blood testing required for 
the study. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 16 of 85 
 
6. Agrees to not take non-dietary probiotics from Screening through 8 
weeks after receiving the last study enema (including OTC and 
prescription). 
7. Agrees to not take any oral vancomycin, metronidazole, 
fidaxomicin, rifaximin, nitazoxanide, bezlotoxumab, or IVIG 
through the 8-week follow-up assessment unless newly prescribed 
by a treating investigator during the course of the study as a result of 
recurrent CDI diagnosis.   Note: Use of IVIG for treatment of a non-
CDI indication is allowed. 
8. Agrees to practice a form of effective contraception during study 
participation; does not apply to persons with documented non-child-
bearing potential. 
9. Has a negative urine pregnancy test at the time of enrollment and on 
the day of each enema prior to administration (females of child-
bearing potential only). 
10. Willing and able to provide informed consent, and local privacy 
authorization as applicable. 
11. Willing and able to complete the required Subject Diary. 
12. Willing and able to meet all study requirements, including attending 
all assessment visits and telephone calls. 
Exclusion 
Criteria 
1. A known history of refractory CDI. 
2. Has continued CDI diarrhea despite being on a course of antibiotics 
prescribed for CDI treatment. 
3. Requires systemic antibiotic therapy for a condition other than CDI. 
4. Patient previously participated in a Rebiotix clinical study receiving 
RBX2660. 
5. Fecal microbiota transplant (FMT) within the past 6 months. 
6. FMT with an associated serious adverse event related to the FMT 
product or procedure. 
7. Bezlotoxumab (CDI monoclonal antibodies) if received within the 
last year. 
8. Disease symptoms (e.g., diarrhea) caused by a confirmed intestinal 
pathogen other than C. difficile. 
9. Have a current colostomy. 
10. Intraabdominal surgery within the last 60 days.  Note: laparoscopic 
procedures that do not involve the GI tract are permitted. 
11. Planned surgery requiring perioperative antibiotics through the 8-
week follow-up assessment. 
12. Life expectancy of < 6 months.  
13. CD4 count <200/mm3 during Screening. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 17 of 85 
 
 
 
 
14. An absolute neutrophil count of <1000 cells/µL during Screening. 
15. Known or suspected current (< 90 days) illicit drug use.  Note: 
marijuana use is allowed. 
16. Pregnant, breastfeeding, or intends to become pregnant during study 
participation. 
17. Participating in a clinical study of another investigational product 
(drug, device or other) and has not completed the required follow-up 
period. 
18. Subject is eligible for another RBX2660 study. 
19. Subject, in the opinion of the investigator, for whatever reason, 
should be excluded from the study. 
Study Sites 
Approximately 80 US and Canadian sites will participate in this study. 
Study Sponsor 
Rebiotix Inc. 
2660 Patton Road 
Roseville MN  55113 USA 
www.rebiotix.com 
651-705-8770 
Contract 
Research 
Organization 
Medpace, Inc. 
 
Central 
Laboratory 
Medpace Central Labs LLC 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 18 of 85 
 
5. Background 
RBX2660 (microbiota suspension) is an intestinal microbial suspension prepared from 
human stool obtained from carefully and thoroughly screened healthy human donors.  It 
is being studied for the prevention of recurrent Clostridium difficile infection (CDI).  
RBX2660 is prepared from a standardized amount of stool mixed with saline and a 
cryoprotectant.  It is stored at the manufacturer in a frozen state and is shipped frozen to 
the clinical site for administration via enema. 
The donor selection process is multifaceted in its original screening of candidate donors 
as well as the ongoing assessment of donated samples prior to release for use in a 
clinical study.  Some of these measures include the following:  
1. Donor qualification screening includes questions that specifically address risk 
factors for colonization with multi-drug resistant organisms (MDROs), and 
individuals at higher risk of colonization with MDROs are excluded from donation. 
Examples of persons at higher risk for colonization with MDROs include: 
a. Health care workers 
b. Persons who have recently been hospitalized or discharged from long term care 
facilities 
c. Persons who regularly attend outpatient medical or surgical clinics 
d. Persons who have recently engaged in medical tourism 
2. Donor stool testing includes MDRO testing to exclude use of stool that tests positive 
for MDRO. The MDRO tests include at minimum extended spectrum beta-lactamase 
(ESBL)-producing Enterobacteriaceae, vancomycin-resistant enterococci (VRE), 
carbapenem-resistant Enterobacteriaceae (CRE), and methicillin-resistant 
Staphylococcus aureus (MRSA).  
3. All drug product currently in storage has undergone screening and stool testing for 
MDROs as described above. 
4. The informed consent process for subjects being treated with RBX2660 product as 
part of this study describes the risks of MDRO transmission and invasive infection 
as well as the measures implemented for donor screening and stool testing. 
 
Rebiotix has concluded the first clinical study of RBX2660 (n=34): an open-label, non-
controlled Phase 2 study (Protocol 2013-001) demonstrating the safety of the product.  
Rebiotix has also completed enrollment and interim reports for two additional Phase 2 
clinical studies.  Protocol 2014-01 is a prospective, multicenter, randomized, double-
blinded, placebo-controlled, 3-arm Phase 2 study (n=127 treated) designed to 
demonstrate the efficacy and safety of RBX2660 for the prevention of recurrent CDI.  
Primarily, this Phase 2 study compared the efficacy of two enemas of RBX2660 to two 
enemas of placebo, and secondarily compared the efficacy of two enemas of RBX2660, 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 19 of 85 
 
and one enema of RBX2660 + one enema of placebo to two enemas of placebo.  The 
study has been completed.  Protocol 2015-01 is an open label study comparing the 
efficacy and safety of two planned RBX2660 enemas (n=136 treated) to a historical 
control (n=110).  This study is currently in long-term follow-up. Rebiotix is conducting 
a Phase 3 study (Protocol 2017-01) with expected treatment of up to 270 subjects.  The 
purpose of Protocol 2017-01 is to confirm the efficacy and safety of RBX2660 for the 
prevention of recurrent CDI in subjects who have had prior recurrent CDI that was 
resolved with antibiotic treatment. 
Finally, to complete the RBX2660 clinical development program, Rebiotix is initiating 
this Phase 3 study (Protocol 2019-01) to assess the safety and tolerability of RBX2660 
in a recurrent CDI population that is broader and more inclusive than that included in 
prior studies evaluating RBX2660.  In order to continue to collect prospective safety 
information and allow open-label treatment access to a broad patient population, up to 
750 subjects will be treated with RBX2660. 
The study will be conducted in compliance with this protocol as approved by the federal 
Food and Drug Administration and each site’s governing Institutional Review Board or 
Research Ethics Board (Canada); in accordance with relevant regulations in 21 CFR 
Parts 11, 50, 54, 56 and 312; and the ICH E6 Good Clinical Practice: Consolidated 
Guidance. 
5.1. Investigational Agent 
RBX2660 (microbiota suspension) 50g/150mL is supplied in an enema bag within a 
brown opaque sleeve.  Each bag contains one dose.  Each dose contains a minimum of 
107 microbes/mL of suspension in a saline/polyethylene glycol 3350 vehicle.   
5.2. Preclinical Data 
Fecal transplantation is being used today in many highly respected hospitals throughout 
the world with no significant reports of adverse events or other safety-related 
complications.  Rebiotix conducted an extensive literature review beginning with the 
first published cases of fecal transplantation in 1958 (Eiseman, 1958).  The literature 
presented significant evidence of the safe and effective use of fecal transplant (FT) for 
over 500 cases of recurrent CDI with no product-related adverse events reported to date 
and only a few procedure-related events, none of which occurred in subjects receiving 
FT via enema (Bakken, 2015).  Based on the significant human clinical experience 
documented in the literature, it has been determined that preclinical studies are not 
warranted. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 20 of 85 
 
5.3. Clinical Data to Date 
5.3.1. Phase 2 Study Protocol 2013-001 Final Data 
On July 12, 2013, Rebiotix received permission from FDA to proceed with the Phase 2 
clinical study entitled “A Phase 2 Open-label Clinical Trial Demonstrating the Safety of 
RBX2660 Microbiota Suspension for the Treatment of Recurrent Clostridium difficile-
associated Diarrhea.”  This study ended with the last subject’s 6-month assessment in 
July 2014.   
It was a prospective, multi-center, open-label, non-controlled Phase 2 study designed to 
demonstrate the safety of RBX2660 (50 g/150 mL) for the treatment of recurrent CDI.  
The target population was adults (≥ 18 years old) with recurrent CDI who had either a) 
at least two recurrences after a primary episode (primary episode + ≥ two recurrences, 
i.e., at least three episodes) and had completed at least two rounds of standard-of-care 
oral antibiotic therapy or b) had at least two episodes of severe CDI resulting in 
hospitalization.  Protocol 2013-001 was the first study assessing the safety of RBX2660, 
although similar fecal transplant products have been used in humans for many years, as 
discussed in the literature.  The study’s primary objective was to assess the safety of 
RBX2660, but additional information was gathered on efficacy and quality of life.  
Eligible subjects who proceeded to treatment received one treatment with RBX2660.  If 
their CDAD returned before Day 56 after receiving one treatment, they were eligible to 
receive a second treatment if the re-treatment occurred within ten days of recurrence.   
Follow-up visits occurred at Days 7, 30 and 60, and subjects remained in the study for 
telephone assessments for adverse events at 3 and 6 months.  If a subject received a 
second treatment, the follow-up schedule was re-set, so that they came in for visits at 7, 
30 and 60 days after the second treatment and receive 3- and 6-month telephone 
assessments.  Subjects also kept a written diary for the first 60 days after each treatment 
with RBX2660, including the collection of detailed information on solicited adverse 
events for the first eight days after receiving an RBX2660 enema. 
A total of 40 subjects were enrolled in this study.  Of these, six did not proceed to 
receive a treatment with RBX2660 (screen failures).  Of the 34 treated subjects, two 
subjects terminated their participation in the study around their respective 7-day visit.  
One subject died 35 days after receiving their second treatment with RBX2660 from 
respiratory failure, which was not related to RBX2660 or the administration procedure.  
All subjects completed the study (6-month telephone assessment after their last 
treatment with RBX2660).   
Efficacy Results 
The primary efficacy parameter of this study was treatment success, defined as the 
absence of CDAD (passage of three or more unformed stools in 24 or fewer consecutive 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 21 of 85 
 
hours for at least two consecutive days) at 56 days after the last treatment with 
RBX2660.  Of the 34 subjects who received at least one treatment with RBX2660, 31 
subjects were presented in the efficacy analysis (31 had efficacy data available).  
Twenty-seven (27) out of 31 subjects, or 87.1%, were considered a treatment success.  
Sixteen (16) subjects or 50.0% (N=16/32) were considered a treatment success after 
their first treatment with RBX2660.  Of the 16 subjects who failed their first treatment, 
15 subjects proceeded to receive a second enema of RBX2660.  Of those, 11 subjects or 
78.6% (N=11/14) were considered a treatment success (one subject was not counted 
because she did not reach the 56-day endpoint).  The reasons for the increased rate of 
success after the second enema were not fully understood.  It may be due to a number of 
factors, including changes in the subject’s microbiome after one treatment, complete 
elimination of vancomycin from the subject’s stool over time, or other reasons not yet 
determined. 
Safety Results 
The subjects enrolled in Protocol 2013-001 had significant pre-existing comorbidities.  
Even with their recurrent CDI symptoms temporarily controlled by standard-of-care 
antibiotic therapy, they remained very sick people.  The incidence, severity, and 
seriousness of the adverse events observed in this study represented the first attempt to 
systematically and rigorously collect, and consistently analyze and characterize them in 
a subject group suffering from recurrent CDI who were treated with an intestinal 
microbiota fecal transplant product.  There were 188 adverse events reported by 28 
subjects, which were gathered through the very rigorous solicitation of events.  The 
adverse events reported were mostly mild-to-moderate in severity and were primarily 
related to gastrointestinal disorders as was expected in this population.  Most resolved 
within the 7-day interval after RBX2660 administration.  This was true whether the 
subject received one or two treatments with RBX2660.   
Of the reported solicited events, which were collected during the 8-day period inclusive 
of the day of dosing and the subsequent 7-day follow-up period, the incidence and 
severity of these events declined over the 8-day period.  The proportion of subjects 
reporting solicited AEs was lower on Day 7 in subjects who received two treatments 
(41.7%; N=5/12) with RBX2660 than in subjects who received one treatment (51.5%; 
N=17/33), yet the efficacy rate after two treatments rose from 50% to 78.6% after one 
treatment.  There were seven subjects who experienced a total of 20 SAEs, only one of 
which had a possible relationship to RBX2660; most were probably or definitely related 
to a pre-existing condition, including CDI.  Overall, adverse events declined over time; 
66.5% of AEs occurred from Baseline through the 7-day visit.  This was the first known 
study to prospectively, systematically, consistently and aggressively solicit, record, and 
classify adverse events in subjects who received an intestinal microbiota fecal transplant 
product.  It was therefore expected that the incidence rate of reported AEs might be 
higher than that reported in the literature, but it represented the true rate and types of 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 22 of 85 
 
events experienced by this population after treatment with an intestinal microbiota fecal 
transplant product. 
Figure 5-1 shows the decline in the proportion of subjects reporting solicited adverse 
events over the 8 days from the day of dosing (Day 0) to the seventh day after dosing 
(Day 7). 
 
 
Figure 5-1:  Proportion of Subjects Reporting Solicited AEs from Day 0-Day 7 
Conclusions 
The RBX2660 treatment success rate of 87.1% represented a significant improvement 
over reported success rates for oral antibiotics and was within the range of results 
reported in the literature for similar fecal microbiota products.  This was the first known 
study to prospectively, systematically, consistently and aggressively solicit, record, and 
classify adverse events in subjects who received an intestinal microbiota fecal transplant 
product.  It was therefore expected that the incidence rate of reported AEs (188 events in 
28 subjects) might be higher than that reported in the literature, but it represented the 
true rate and types of events experienced by this population receiving this therapy.  The 
incidence rate and type of adverse events were not unexpected, given the high number of 
comorbidities that existed in this very sick, primarily elderly population.  None of the 
SAEs were determined to be probably or definitely related to RBX2660 and most were 
related to a pre-existing condition, primarily C. difficile infection.  The success rate 
increased after two treatments with RBX2660, yet the proportion of subjects reporting 
solicited AEs was lower on Day 7 in subjects who received two treatments than in 
subjects who received one treatment.  The efficacy benefit of RBX2660 outweighed the 
incidence and type of adverse events, especially the risk of recurrent CDI, thus 
providing a satisfactory benefit-to-risk ratio. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 23 of 85 
 
5.3.2. Phase 2 Study Protocol 2014-01 Final Study Data 
Study Design 
Study Protocol 2014-01 was a prospective, multicenter, randomized, double-blinded, 
placebo-controlled, 3-arm Phase 2B study demonstrating the efficacy and safety of 
RBX2660 for the treatment of recurrent CDI (rCDI).  The target population was adults 
(≥ 18 years old) with rCDI who had either a) at least two recurrences after a primary 
episode (i.e., at least three episodes) and had completed at least two rounds of standard-
of-care oral antibiotic therapy or b) had at least two episodes of severe CDI resulting in 
hospitalization.  Randomization was at a 1:1:1 ratio to one of the three groups: Group A 
(2 enemas of RBX2660), Group B (2 enemas of placebo), and Group C (1 enema of 
RBX2660 and 1 enema of placebo). One complete study treatment consisted of two 
enemas administered 7 ± 2 days apart; the second enema could be administered sooner if 
CDI diarrhea (passage of ≥ 3 unformed stools in ≤ 24 consecutive hours for at least two 
consecutive days) recurred in less than 7 days.   
Efficacy Results 
A total of 150 subjects were enrolled in the study and 133 were randomized (Intent-to-
Treat, ITT, N=45 in Group A, N=44 in Group B, and N=44 in Group C) of which five 
(5) subjects were withdrawn prior to treatment.  In total, 128 randomized subjects were 
exposed to blinded enema (Safety Population, SP), with 127 subjects successfully 
completing at least one blinded enema.  
The primary efficacy parameter of this study was Treatment Success, defined as the 
absence of CDAD (passage of three or more unformed stools in 24 or fewer consecutive 
hours for at least two consecutive days) at 56 days after the last treatment with 
RBX2660.  The efficacy objectives of the study were analyzed using all three analysis 
populations: ITT, modified ITT, and Per Protocol (PP).   
The primary efficacy objective of Group A as compared to Group B was not met, 
however, a sensitivity analysis of a secondary efficacy objective using the PP population 
comparing Group C to Group B did achieve statistical significance (p=0.017). A 
comparison of the active RBX2660 treatment Groups A and C demonstrated no 
statistical difference indicating that there was no efficacy difference between one or two 
enemas of RBX2660.   
Safety Results 
Adverse events were collected for each subject by the investigational sites and solicited 
via a subject diary from the point of enrollment (information consent) through study 
exit.  Safety results were analyzed using the SP, which consisted of any subject who had 
an attempted study drug administration (N=128), whether placebo or RBX2660.  There 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 24 of 85 
 
were 907 AEs reported by 106 subjects.  Of those AEs, 841 events in 105 subjects 
occurred after administration of study IP and are termed treatment emergent adverse 
events (TEAEs).  The TEAEs reported were mostly mild-to-moderate in severity 
(87.6%) and were primarily related to gastrointestinal disorders (32.5%) as would be 
expected in this population.   
Overall Results 
These results indicate that one or two doses of RBX2660 is a safe and potentially 
effective therapy for rCDI. 
5.3.3. Phase 2 Study Protocol 2015-01 Final Study Data 
Study Design 
Study protocol 2015-01 was a prospective, multicenter, open-label Phase 2 study that 
assessed the efficacy and safety of RBX2660 as an adjunct to antibiotics for the 
treatment of rCDI, as compared to a historical control population of subjects treated with 
standard-of-care antibiotic therapy. The study population was adults (≥ 18 years old) 
with rCDI who had either: a) at least two recurrences after a primary episode and had 
completed at least two rounds of standard-of-care oral antibiotic therapy, or b) at least 
two episodes of severe CDI resulting in hospitalization.  
The primary efficacy objective of Treatment Success for the study was measured by the 
recurrence-free rate of CDI diarrhea without the need for retreatment with C. difficile 
anti-infective therapy or fecal transplant through 56 days after completion of study 
treatment with RBX2660. One treatment consisted of 2 enemas of RBX2660 7 ± 2 days 
apart. Subjects were expected to participate in the study for approximately 25-27 
months: 1 month enrollment; 8 weeks efficacy follow-up; and an additional 22 months 
for safety follow-up. 
A total of 272 subjects enrolled in the study, including 110 subjects in the Historical 
Control arm, 13 subjects enrolled but not treated, and 149 subjects received at least one 
(1) enema (Safety Population, SP).  In total, 217 subjects were evaluable for treatment 
outcome and followed for at least 56 days (day 49 – 63) after the last treatment 
(Evaluable Population).  
Efficacy Results   
The efficacy objectives of the study were analyzed using RBX2660 treated subjects 
(n=142) who received at least one enema and were evaluable for a treatment outcome.  
This arm was compared to a closely matched Historical Control arm (n=75) chosen from 
a retrospective chart review of subjects treated with antibiotics for rCDI who matched 
key eligibility criteria and had an evaluable treatment outcome. The primary endpoint, 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 25 of 85 
 
proportion of subjects with Treatment Success, was significantly greater in the 
RBX2660 arm (78.9%) as compared with the Historical Control arm (30.7%; p<0.0001; 
Pearson’s chi-square test, Evaluable Population).   
Safety Results   
A total of 879 adverse events were reported in 124 subjects (83.2% of subjects) in the 
RBX2660 treatment arm.  A similar total and percentage of adverse events were 
documented in the Historical Control arm (n=767 events in 71 subjects; 68.3% of 
subjects).  In the RBX2660 arm, 805 treatment-emergent adverse events (TEAEs) were 
reported in 123 subjects (82.6% of subjects).  The TEAEs reported were mostly mild-to-
moderate in severity (84.1%), and the most common TEAEs overall were diarrhoea, 
abdominal pain and urinary tract infections in descending order. In the Historical 
Control arm, 665 TEAEs were reported in 67 subjects. Severity was not collected for 
events in the Historical Control arm. The most common TEAEs overall were urinary 
tract infections, back pain, diarrhoea, and oedema peripheral in descending order. 
In the RBX2660 treated arm, 208 serious TEAEs were reported in 52 subjects (25.8% of 
all TEAEs).  In the Historical Control arm, 83 serious TEAEs were reported for 30 
subjects (12.5%).  AEs resulting in Death were recorded for 15 RBX2660 treated 
subjects (10.1%), one of which was reported as possibly related to IP or enema 
procedure and definitely related to C. difficile disease and pre-existing condition(s).  
Death was reported for five of the subjects in the Historical Control arm (4.8%). 
Overall Results   
With this study, the efficacy results for RBX2660 are demonstrated to be repeatable, and 
the safety profile is acceptable for this patient population.  The efficacy and safety 
observed in this study demonstrate that RBX2660 has an appropriate benefit-risk 
assessment as a treatment for rCDI. 
5.3.4. Phase 3 Study Protocol 2017-01 Final Study Data 
Study Design:  
Study Protocol 2017-01 was a prospective, multi-center, double-blind, placebo-
controlled Phase 3 study to evaluate the efficacy and safety of RBX2660 for the 
prevention of rCDI in 267 subjects randomized and treated in a 2:1 ratio to receive 
RBX2660 (Group B) or Placebo (Group A). The primary endpoint was the recurrence of 
CDI within 8 weeks of blinded treatment. The secondary endpoint was the loss of 
sustained clinical response through 6 months after blinded treatment. Safety endpoints 
included the number of AEs per subject, timing of attributable TEAEs, relatedness and 
severity of TEAEs.  


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 26 of 85 
 
Efficacy Results:  
In total, 262 subjects had adjudicated outcomes for the primary endpoint in the mITT 
population. The primary statistical analysis used a Bayesian hierarchical model which 
formally incorporated data from a previous randomized Phase 2B study (Protocol 2014-
01). RBX2660 demonstrated a 98.6% probability of superiority compared to Placebo in 
the prevention of CDI recurrence, with a success rate of 70.4% vs 58.1% through 8 
weeks of blinded treatment. The posterior probability of superiority (0.986354) 
exceeded the threshold of 0.9750338 that controlled the Type I error rate at one-sided 
0.025.  
Sustained Clinical Response (Treatment Success at 8 weeks and no CDI recurrence for 6 
months) was 90.6% (48/53) and 92.1% (116/126) in the Placebo and RBX2660 groups, 
respectively. Although there was no statistically significant difference between the two 
groups, the separation between RBX2660 and Placebo observed at 8 weeks was durable 
through 6 months. 
Safety Results:  
Of the 267 subjects in the safety population, 178 subjects (66.7%) reported a total of 708 
TEAEs throughout the duration of the study; 478 TEAEs were reported by 154 (57.7%) 
subjects within 8-weeks of either treatment and 230 TEAEs were reported by 84 
(31.5%) subjects more than 8-weeks after either treatment. More than a half (56.6%, 
401/708) of TEAEs reported throughout the study occurred within 8-weeks of blinded 
treatment, which included solicited AEs collected during follow-up visits and telephone 
assessments and through Subject Diaries. 
When assessed by maximum severity per subject, the majority of TEAEs (317/368, 
86.1%), reported in 147 subjects (82.6%), were assessed as mild-to-moderate, 12.5% 
(46/368) TEAEs were severe, and 1.4 % (5/368) TEAEs were potentially life-
threatening. The most frequently occurring TEAEs (256/708, 36.2%) were related to 
gastrointestinal disorders as would be expected in this population. Of the 54 serious 
TEAEs reported throughout the study, as assessed by investigator, none (0) were related 
to IP, none (0) were related to enema procedure, 16 (29.6%) events were related to C. 
difficile disease, and 40 (74.1%) events were related to a pre-existing condition. Of 
serious TEAEs that occurred within 8 weeks of the blinded period, 20 events occurred in 
13 (4.9%) of subjects. Death was reported in 2 subjects, none (0) were reported as 
related to IP or enema procedure; both deaths were the result of AEs related to a pre-
existing condition (one fatal event of multimorbidity; one fatal event of cardio-
respiratory arrest). 
 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 27 of 85 
 
Overall Conclusions:  
Overall, the primary efficacy endpoint of study 2017-01 met the pre-specified success 
criteria and demonstrated clinically meaningful results. The efficacy outcomes 
demonstrated that RBX2660 was superior to Placebo at reducing recurrence of CDI 
through 8 weeks after completing blinded treatment, response was durable through 6 
months, and the safety profile is acceptable for this patient population. In summary, 
RBX2660 has demonstrated a positive benefit-risk profile for the reduction of CDI 
recurrence in adult patients following antibiotic therapy for rCDI. 
5.3.5. Retrospective Study Protocol 2019-02 Final Study Data 
Study Design: 
Study Protocol 2019-02 was a retrospective, multicenter, safety and tolerability study of 
RBX2660 administered under Enforcement Discretion for the prevention of rCDI. The 
study was intended to obtain safety data from up to 200 patients who received RBX2660 
under Enforcement Discretion during a defined period. The primary endpoint was the 
number of subjects with IP- and/or enema-related TEAEs. The secondary objectives 
were to evaluate efficacy of RBX2660 in preventing recurrent episodes of CDI through 
8 weeks after treatment and loss of Sustained Clinical Response rate of RBX2660 
through 6 months after treatment. 
Efficacy Results: 
In the Primary Safety Set population, Treatment Success through 8 weeks after the last 
dose of RBX2660 was achieved by 53 (82.8%) subjects, and 47 (88.7%) subjects had a 
Sustained Clinical Response through 6 months after the last dose of RBX2660. 
Safety Results: 
TEAEs were considered related to RBX2660 for 11 (17.2%) subjects and related to the 
enema procedure for 3 (4.7%) subjects. In addition, there were 2 deaths reported during 
the study analysis period which were considered not related to RBX2660 or the enema 
procedure. SAEs were experienced by 8 (12.5%) subjects and all SAEs were considered 
not related to RBX2660 or the enema procedure.  
Overall Results: 
RBX2660 was well tolerated and efficacious in this patient population administered 
RBX2660 under Enforcement Discretion. As described, Treatment Success through 8 
weeks after the last dose of RBX2660 was achieved by 53 (82.8%) subjects; of these 
subjects, 47 (88.7%) had a Sustained Clinical Response through 6 months after the last 
dose of RBX2660. These efficacy outcomes were comparable to the outcomes observed 
in previous, prospective, controlled clinical studies of RBX2660. RBX2660 was well 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 28 of 85 
 
tolerated, with few TEAEs attributed to RBX2660 or the enema procedure. The safety 
profile was characteristic of subjects with recurrent CDI and comparable to the safety 
profiles observed in previous clinical studies of RBX2660, suggesting that treatment 
with RBX2660 for recurrent CDI is appropriate for the broader CDI population. 
5.4. Treatment Rationale and Risk/Benefit 
RBX2660 microbiota suspension was developed after careful, controlled component and 
process testing performed by Rebiotix using applicable scientific methods.  RBX2660 
(microbiota suspension) 50 g/150 mL is supplied in an ethylene vinyl acetate enema bag.  
Each bag of RBX2660 contains one enema; each enema of RBX2660 consists of a 
suspension of minimum 107 live organisms/mL in polyethylene glycol 3350/0.9% 
Sodium Chloride Irrigation, USP, solution to ensure a consistent product is delivered.  
The enema route was chosen over other potential routes of administration because the 
risk of procedural complications for the subject is low and the method is easy to perform 
and requires no special equipment.  In addition, the enema route for fecal transplants is 
routinely used and has high efficacy rates reported in the literature with no reports of 
safety issues.   
Recurrent CDI often results in severe and serious consequences.  An assessment of the 
risk associated with recurrent CDI and the benefit of preventing recurrent episodes by 
administering multiple enemas of RBX2660 supports the conclusion that the risk of the 
predominately mild to moderate AEs experienced by subjects in the Phase 2 studies is 
outweighed by the potential benefit.  This study will assess the safety and tolerability of 
RBX2660 in a recurrent CDI population that is broader and more inclusive than that 
included in prior studies using RBX2660.  Data supporting the use of FMT procedures 
to prevent CDI in patient populations similar to those eligible for this study is limited. 
Kelly (2014) reported 12-week safety and efficacy of FMT in 80 immunocompromised 
patients: solid organ transplants (19), HIV/AIDS (3), cancer (7), inflammatory bowel 
disease (IBD, 36), and other chronic medical conditions (15).  Of note, the IBD patients 
did not experience a higher incidence of AEs (14%) or SAEs (11%) compared to other 
immunocompromised patients (16% and 18%, respectively; p≤0.3224).  Three patients 
with IBD (14%) experienced disease exacerbation post FMT, noting that their colonic 
disease activity leading up to FMT was severe.  The rates of AEs and SAEs were 
comparable to those reported in the Rebiotix studies where subjects were followed well 
beyond 12-weeks.  The treatment success rate, with 12 patients receiving two FMTs, 
was 89% demonstrating that the benefit of treatment outweighed the risk. 
Though the risk profile for the broader eligible patient population has not been well 
characterized in multiple, controlled clinical studies, the body of safety and efficacy 
evidence for RBX2660 and other FMT procedures, along with the rigor of Rebiotix’s 
donor screening process, and implementation of quality assurance testing at all stages of 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 29 of 85 
 
manufacturing supports a favorable benefit-to-risk profile for the use of RBX2660 in the 
prevention of recurrent CDI. 
6. Study Objectives and Endpoints 
6.1. Primary Objective 
To evaluate the safety and tolerability of RBX2660 in subjects with recurrent CDI. 
6.2. Secondary Objectives 
1. To evaluate the efficacy of RBX2660 in preventing recurrent episodes of CDI 
through 8 weeks after treatment. 
2. To evaluate the sustained clinical response rate of RBX2660 after treatment. 
6.3. Other Objectives 
1. To evaluate health-related quality of life in subjects with CDI as measured by the 
Cdiff32 questionnaire. 
2. To identify Baseline characteristics predictive of efficacy outcomes. 
3. To characterize the changes from the Baseline fecal microbial composition at 
each timepoint. 
4. To evaluate the efficacy of a second dose of RBX2660 in preventing CDI 
recurrence. 
5. To assess the clearance of vancomycin resistant enterococcus in subjects who are 
carriers at Baseline. 
6. To assess the clearance of C. difficile following enema treatment at 1-week, 4-
weeks, 8-weeks, 4-months, and 6-months after study treatment in subjects 
receiving RBX2660. 
6.4. Primary Endpoint 
Number of subjects with investigational product- and/or enema-related treatment-
emergent adverse events (TEAEs). 
6.5. Secondary Endpoints 
1. Recurrence of CDI within 8 weeks of treatment. 
2. Loss of sustained clinical response through 6 months after treatment.  
6.6. Safety Endpoints 
1. Number of adverse events per subject 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 30 of 85 
 
2. Timing of attributable TEAEs 
3. Duration of TEAEs 
4. Relatedness of TEAEs 
5. Severity of TEAEs 
6. Causality of TEAEs to IP, enema, C. difficile or prior condition  
7. Number of each of the following CDI-related TEAEs through 8-weeks post 
treatment: death, septic shock, toxic megacolon, colonic perforation, emergency 
colectomy, and ICU admission  
8. Onset of new chronic conditions relative to treatment administration 
6.7. Other Endpoints 
1. Baseline characteristics: sex, age, number of prior CDI events, race, ethnicity  
2. Subject fecal microbial composition at Screening, 1-week, 4-weeks, 8-weeks, 4 
months, and 6 months after study treatment 
3. Cdiff32 questionnaire at Screening, 1-week, 8-weeks, 4 months, and 6 months 
4. Recurrence of CDI within 8 weeks of a second RBX2660 treatment  
5. Concentration of vancomycin resistant enterococcus in stool samples at 
Screening, 1-week, 4-weeks, 8-weeks, 4 months, and 6 months after study 
treatment 
6. Presence of C. difficile in stool samples at Screening, 1-week, 4-weeks, 8-weeks, 
4 months, and 6 months after study treatment 
7. Study Design 
7.1. Study Purpose 
The purpose of this study is to assess the safety and tolerability of RBX2660 in subjects 
with recurrent CDI who have had prior recurrent CDI that was resolved with antibiotic 
treatment. 
7.2. General Study Design 
This is an open-label, Phase 3 study to evaluate the safety and tolerability of RBX2660 
in subjects with recurrent CDI.  
Up to 750 subjects may be treated in this study.  Consented subjects who meet all 
eligibility criteria are intended to be treated.  Consented subjects who do not meet the 
eligibility criteria will be considered screen failures and will not count towards the total 
number of subjects treated. 
Potential subjects are expected to already be taking or have just been prescribed 
antibiotics to control recurrent CDI symptoms at the time of enrollment (Screening visit) 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 31 of 85 
 
per the investigator’s standard of care.  Patients who have already completed their 
prescribed course of antibiotics to treat recurrent CDI are not eligible for enrollment 
(Screening visit) unless they have another recurrence that is treated with antibiotics. 
Once the Screening visit is complete, in order to proceed to the Baseline Enema 
Administration: 
1. Subject must meet all the inclusion and none of the exclusion criteria 
2. Antibiotics will have been administered prior to the washout period 
3. CDI symptoms must be under control leading into the antibiotic washout period 
(Section 7.3.1) 
Control of CDI symptoms is defined as no longer meeting the symptomatic criteria for 
CDI diarrhea which is the passage of three or more unformed/loose (i.e., Bristol Stool 
Scale type 6-7) stools in 24 or fewer consecutive hours while taking antibiotics for the 
two consecutive days prior to the washout period.  Thus, at a minimum the Subject 
Diary which is started at the Screening visit must show that symptoms are under control 
the two days prior to the washout period in order for the subject to receive the enema 
administration.     
Study treatment (enema administration) is to be completed as soon as possible, but no 
later than 21 days after the Screening visit.  A minimum of 24hr to a maximum of 72hr 
antibiotic washout period is required prior to administration of the study treatment. 
In-office study follow-up visits will occur at weeks 1 and 8 after completing the 
Baseline visit.  Telephone assessments will occur at week 4 and at months 4 and 6 after 
the Baseline visit.  Subjects are required to keep a detailed diary to assess for solicited 
events from the date of Screening visit to the 1-week follow-up visit.  The diary will be 
collected and reviewed at the Baseline visit prior to enema administration.  The subject 
will continue to complete the diary for one week following the Baseline visit (enema 
administration) and it will be collected and reviewed at the 1-week follow-up visit. 
Subjects may receive a second RBX2660 enema if they are deemed failures following 
treatment per the protocol-specified treatment failure definition (Section 7.3.6).  This 
second enema is to be administered within 21 calendar days of failure determination.  If 
a subject receives a second RBX2660 enema, the follow-up is completed via telephone 
assessments at 1-week, 8-weeks, and 6-months after completing the second enema.  A 
final analysis and report will be completed once the last subject has completed the 6-
month follow-up visit for their study treatment, including 6-month follow-up after a 
second RBX2660 study treatment, if applicable.   
See Figure 7-1 for an illustration of the Study Design. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 32 of 85 
 
  
 
Figure 7-1: Open-Label Study Design. 
7.3. Study Definitions 
7.3.1. Control of symptoms during antibiotic use 
Control of CDI symptoms during antibiotic use is defined as no longer meeting the 
symptomatic criteria for CDI diarrhea which is the passage of three or more 
unformed/loose (i.e., Bristol Stool Scale type 6-7) stools in 24 or fewer consecutive 
hours while taking antibiotics for the two consecutive days prior to the washout period.  


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 33 of 85 
 
Thus, at a minimum the Subject Diary which is started at the Screening visit must show 
that symptoms are under control the two days prior to the washout period in order for the 
subject to receive the enema administration. 
7.3.2. Indeterminate Treatment Outcome 
If neither the protocol-specified definition for Treatment Success nor Treatment Failure 
is met, the treatment outcome will be considered Indeterminate.  
7.3.3. Medications 
7.3.3.1. 
Prior Medications 
Prior medications are defined as any medication (prescription or non-prescription), 
nutritional supplement, or herbal preparation taken or used within 30 days prior to the 
first dose of study drug. 
7.3.3.2. 
Concomitant Medications 
Concomitant medications are defined as any medication (prescription or non-
prescription), nutritional supplement, or herbal preparation taken or used from first dose 
of study drug through 6-month follow-up assessment/end of study.  
Concomitant medication information including changes to doses will be recorded in the 
study database from the Baseline visit through the 6-month follow-up assessment/end of 
study.  
7.3.3.3. 
Prohibited Medications 
Prohibited medications include any oral vancomycin, metronidazole, fidaxomicin, 
rifaximin, nitazoxanide, bezlotoxumab, or IVIG through the 8-week follow-up 
assessment unless newly prescribed by a treating investigator during the course of the 
study as a result of recurrent CDI diagnosis.  Use of IVIG for treatment of a non-CDI 
indication is allowed.  Use of non-dietary probiotics from Screening through 8 weeks 
after receiving the last study enema (including OTC and prescription) is also prohibited.  
Medication information will be collected at the Screening visit and changes in 
medications will be recorded throughout the study.   
7.3.4. Recurrent CDI 
The following are study definitions for recurrent CDI.   
7.3.4.1. 
Recurrent CDI for Study Entry 
To be considered for enrollment, a subject must have medical record documentation of:  
a)   a current diagnosis or history of recurrent CDI as determined by the treating 
physician,   


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 34 of 85 
 
b) or has had at least two episodes of severe CDI resulting in hospitalization. 
7.3.4.2. 
Recurrent CDI On-study  
1. The passage of three or more unformed/loose (i.e., Bristol Stool Scale type 6-7) 
stools in 24 or fewer consecutive hours for at least two consecutive days, 
2. and a positive stool test for the presence of C. difficile as determined by the 
central laboratory. 
7.3.5. Sustained Clinical Response  
Sustained clinical response is defined as:  
• Treatment success of the presenting CDI recurrence and no new CDI episodes 
through 6 months after completing a study treatment. 
7.3.6. Treatment Failure 
Treatment failure (CDI recurrence) is defined as:  
• The presence of CDI diarrhea within 8 weeks of administration of a study 
enema, which includes a positive stool test for C. difficile as determined by 
the central laboratory.  
7.3.7. Treatment Success 
Treatment success is defined as: 
• The absence of CDI diarrhea through 8 weeks after completing a study 
treatment.  
7.4. Determination of Treatment Success/Failure 
The site investigator makes the initial determination of treatment success or failure 
based on the pre-defined study definitions (Section 7.3.1, 7.3.6, and 7.3.7).  The site 
investigator’s assessment will then be provided to the Endpoint Adjudication Committee 
(EAC) for independent adjudication of treatment success or failure that will be utilized 
for study analysis and reporting purposes.  This may be done on an on-going basis or a 
single meeting.  Details of the EAC logistics, activity and responsibilities will be 
included in an EAC charter.   


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 35 of 85 
 
7.5. Management of Treatment Failure 
Following treatment, subjects meeting the protocol definition of treatment failure 
(Section 7.3.6) may be scheduled for administration of a second RBX2660 enema 
within 21 calendar days of failure determination.  To receive the second RBX2660 
enema, the site must provide documentation of meeting all treatment failure criteria as 
defined in Section 7.3.6.  If the definition of treatment failure is not met, a second study 
treatment of RBX2660 will not be provided.  
Treatment failures are required to be entered in the study database shortly after 
determination of failure to allow for sponsor awareness and assurance that a second 
study treatment of RBX2660 can be provided if requested.  
The use of antibiotics prior to a second RBX2660 enema is at the discretion of the 
investigator.  If antibiotics are given to control symptoms, a 24-72 hour washout period 
prior to administration of a second RBX2660 enema is required.  If the subject will have 
a second enema, it needs to be administered within 21 calendar days of failure 
determination.   
If a subject receives a second RBX2660 enema, follow-up is completed via telephone 
assessments at 1-week, 4-weeks, 8-weeks, and 6 months after the second study treatment 
of RBX2660. 
Treatment failures who do not receive a second RBX2660 enema will continue to follow 
their original schedule of assessments for the duration of the study based on the first 
study enema. 
If a subject has a treatment failure after receiving a second study treatment of RBX2660, 
the subject should be treated per the investigator’s discretion.   
7.6. Medical Monitor 
The Medical Monitor provides review of serious adverse events or events reported by 
the site as related to the investigational product or enema procedure to assess accuracy 
of reporting as related to seriousness and causality, and periodic review of adverse 
events for trends.  Details of this review are documented in a Safety Management Plan.  
The Medical Monitor’s review will be provided to the DSMB for analysis purposes and 
as applicable for the proper adjudication of potential study stopping rules. 
7.7. Data and Safety Monitoring Board 
The DSMB will review safety data for trends for the final analysis.  Details regarding 
DSMB responsibilities related to analysis oversight, data reporting, and timing of 
meetings will be provided in the DSMB Charter.  


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 36 of 85 
 
7.8. Endpoint Adjudication Committee 
The Endpoint Adjudication Committee (EAC) provides independent adjudication of 
treatment success or failure that will be used for study analysis and reporting purposes.  
Details of the EAC logistics, activity and responsibilities will be included in an EAC 
charter.   
7.9. Bias 
This is an open-label study with a single arm.  The study is not blinded.  Measures taken 
to minimize bias include selection of qualified investigators and study sites, adherence to 
the eligibility criteria (Section 8), and adherence to this protocol. 
 
8. Subject Selection and Withdrawal 
8.1. Inclusion Criteria 
All responses must be “yes” to include a subject in the study: 
1. ≥ 18 years old.  
2. Medical record documentation of either a) a current diagnosis or history of 
recurrent CDI  as determined by the treating physician, b) or has had at least two 
episodes of severe CDI resulting in hospitalization.  
3. Is currently taking or was just prescribed antibiotics to control CDI related 
diarrhea at the time of enrollment.  Note: Subject’s CDI diarrhea must be 
controlled (<3 unformed/loose, i.e., Bristol Stool Scale type 6-7, stools/day for the 
two consecutive days prior to the washout period) while taking antibiotics during 
screening. 
4. Willing and able to have an enema(s). 
5. Willing and able to complete the stool and blood testing required for the study. 
6. Agrees to not take non-dietary probiotics from Screening through 8 weeks after 
receiving the last study enema (including OTC and prescription). 
7. Agrees to not take any oral vancomycin, metronidazole, fidaxomicin, rifaximin, 
nitazoxanide, bezlotoxumab, or IVIG through the 8-week follow-up assessment 
unless newly prescribed by a treating investigator during the course of the study 
as a result of recurrent CDI diagnosis. Note: Use of IVIG for treatment of a non-
CDI indication is allowed. 
8. Agrees to practice a form of effective contraception during study participation; 
does not apply to persons with documented non-child bearing potential. 
9. Has a negative urine pregnancy test at the time of enrollment and on the day of 
each enema prior to administration (persons of child-bearing potential only). 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 37 of 85 
 
10. Willing and able to provide informed consent, and local privacy authorization as 
applicable. 
11. Willing and able to complete the required Subject Diary. 
12. Willing and able to meet all study requirements, including attending all 
assessment visits and telephone calls.  
8.2. Exclusion Criteria 
All responses must be “no” to include a subject in the study: 
1. A known history of refractory CDI. 
2. Currently has continued CDI diarrhea despite being on a course of antibiotics 
prescribed for CDI treatment. 
3. Requires systemic antibiotic therapy for a condition other than CDI. 
4. Patient previously participated in a Rebiotix clinical study receiving RBX2660. 
5. Fecal microbiota transplant (FMT) within the past 6 months. 
6. FMT with an associated serious adverse event related to the FMT product or 
procedure. 
7. Bezlotoxumab (CDI monoclonal antibodies) if received within the last year. 
8. Disease symptoms (diarrhea) caused by a confirmed intestinal pathogen other 
than C. difficile. 
9. Currently has a colostomy. 
10. Intraabdominal surgery within the last 60 days. Note: laparoscopic procedures 
that do not involve the GI tract are permitted.  
11. Planned surgery requiring perioperative antibiotics through the 8-week follow-up 
assessment. 
12. Life expectancy of < 6 months.  
13. CD4 count <200/mm3 during Screening. 
14. An absolute neutrophil count of <1000 cells/µL during Screening. 
15. Known or suspected current (< 90 days) illicit drug use.  Note: marijuana use is 
allowed.   
16. Pregnant, breastfeeding, or intends to become pregnant during study participation. 
17. Participating in a clinical study of another investigational product (drug, device or 
other) and has not completed the required follow-up period. 
18. Subject is eligible for another RBX2660 study. 
19. Subject, in the opinion of the investigator, for whatever reason, should be 
excluded from the study. 
8.3. Subject Recruitment and Screening 
Subjects are recruited by qualified and trained site personnel when they are identified as 
recently diagnosed with or experiencing recurrent CDI or are experiencing at least a 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 38 of 85 
 
second hospitalization due to CDI.  Potential subjects are to be fully informed as to this 
study’s purpose, requirements, anticipated risks, etc., and are to be given the chance to 
review the informed consent form and receive satisfactory answers to all questions.  
Subjects sign the study-specific, IRB/REB-approved Informed Consent and local 
privacy authorization (as applicable), which is the point at which the potential subject is 
considered enrolled in the study.   
Subjects are eligible to receive study treatment upon confirmation that they have met all 
eligibility criteria listed in Sections 8.1 and 8.2.  Antibiotics being taken for their 
recurrent CDI symptoms must stopped for a 24-72 hour washout period prior to 
receiving the study enema. 
 
9. Investigational Product 
9.1. RBX2660 Description  
RBX2660 microbiota suspension 50 g/150 mL is supplied in an enema bag.  Each bag of 
RBX2660 provides one enema.  Each enema of RBX2660 consists of a suspension of 
minimum 107 live organisms/mL in polyethylene glycol 3350/0.9% Sodium Chloride 
Irrigation, USP, solution. 
9.2. Rebiotix Kit Description  
Investigational product is supplied in a single-enema bag fitted with a spike port and a 
rectal tube assembly that is used to administer IP as an enema; these components are 
packaged together in the Rebiotix Kit.  Rebiotix Kit components include: 
 1 bag of RBX2660 with a spike port contained in a brown opaque sleeve 
 1 rectal tube assembly 
 1 biohazard disposal bag 
 1 Instructions for Use (IFU) 
9.3. Treatment Regimen 
Study treatment needs to be administered within 21 days of the Screening visit. Product 
is to only be administered by the authorized IP Administrator who must be a qualified 
and trained health care professional following the Instructions for Use and standard site 
procedures.  Subjects are to remain at the site under supervision for at least one-hour 
post-enema administration for vital sign assessment (temperature, heart rate, blood 
pressure, respiratory rate) and observation.   


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 39 of 85 
 
Subjects with a documented treatment failure following treatment may be scheduled for 
administration of a second RBX2660 enema.  In order to receive a second RBX2660 
enema, a subject must have documentation of meeting all treatment failure criteria as 
defined by the protocol (Section 7.3.6).  
If, in the opinion of the investigator, antibiotics are warranted for the control of CDI 
symptoms prior to receiving the second RBX2660 enema, they can be administered but 
need to be stopped 24-72 hours before enema administration.  The total time from a 
treatment failure (CDI recurrence) determination to administration of a second enema is 
within 21 calendar days.   
See Section 10 for the Schedule of Study Procedures and detailed description of the 
requirements. 
9.4. Subject Follow-up Requirements 
Subjects are assessed at office visits at 1- and 8-weeks and via telephone calls at 4-
weeks and at 4 and 6 months after the study enema.  See Section 10 for follow-up 
assessments and phone calls, and Section 10.16 for subject withdrawal/termination. 
9.5. Concomitant Therapy 
The subject must agree to not take any oral vancomycin, metronidazole, fidaxomicin, 
rifaximin, nitazoxanide, bezlotoxumab, or IVIG through the 8-week follow-up 
assessment unless newly prescribed by a treating investigator during the course of the 
study as a result of recurrent CDI diagnosis.  Use of IVIG for treatment of a non-CDI 
indication is allowed.  Use of non-dietary probiotics from Screening through 8 weeks 
after receiving the last study enema (including OTC and prescription) is also prohibited.   
Medication information will be collected at the Screening visit and changes in 
medications will be recorded throughout the study.  Subjects should be encouraged to 
notify their general practitioners of study participation and the requirements for 
concomitant therapy.  
9.6. Preparation of Investigational Product 
Instructions for Use with detailed directions for IP preparation and administration are 
included in each Rebiotix Kit. 
 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 40 of 85 
 
9.7. Packaging 
Investigational product is supplied in an enema bag fitted with a spike port and a rectal 
tube assembly that is used to administer the product via enema; these components are 
packaged together in the Rebiotix Kit.  
9.8. Ordering, Receipt and Storage, Dispensing, Returning, and Tracking Investigational 
Product 
9.8.1. Ordering Investigational Product  
Authorized site personnel will order IP through the study database.  If a subject is a 
confirmed treatment failure and will proceed to a second RBX2660 treatment, the site 
will document the failure in the database, and complete a re-order form in the database 
to trigger a shipment of IP for the second RBX2660 treatment. 
9.8.2. Receipt and Storage of Investigational Product 
Note:  Each unit of IP is designated to be administered to a specific subject on a specific 
date; administration of IP designated for one subject to another subject is prohibited.   
IP is shipped to the authorized person/department as specified on the Delegation of 
Authority log at the site in a temperature-controlled shipping package.  The authorized 
person opens the shipping package, visually confirms that the unit of IP arrived intact, 
confirms that the temperature indicator has not been tripped and records receipt and 
inspection on the Product Accountability Log.  IP is to be thawed and stored in the 
refrigerator until administration.   
IP must be kept in a secure location under the control of the Investigator or authorized 
designee at all times; see Section 9.8.5 for details.  IP must be administered to the 
subject by the expiration date as specified on the label.  If it is not administered by the 
expiration date, it must be destroyed by site staff per the institution’s processes and be 
recorded on the Product Accountability Log. 
9.8.3. Dispensing and Administering Investigational Product 
Dispensing procedures vary from site to site, but each site’s study investigator is 
responsible for delegating the administration of IP to a qualified and trained health care 
professional; this person(s) (“IP Administrator”) must be identified on the Delegation of 
Authority Log and receive product-specific training on IP administration.   
IP is to be administered by the IP Administrator after all inclusion/exclusion criteria 
have been met, the subject had a negative pregnancy test (if applicable) and the 24-72 
hour antibiotic washout period has been completed.  Administration is via enema 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
   CONFIDENTIAL  
 
 
  Page 41 of 85 
 
following the Instructions for Use in each product package and the site’s standard 
procedures.   
9.8.4. Returning IP 
Do not return IP to Rebiotix.  IP received but not administered to a subject must be 
destroyed by site staff per the institution’s processes.  Destruction must be recorded on 
the Product Accountability Log.  
9.8.5. Product Accountability and Tracking 
Each unit of IP is sent to the site for administration to an assigned subject and is labeled 
with a batch number to be recorded in the electronic case report form (eCRF) and on the 
Product Accountability Log.  Each unit must be tracked on the Product Accountability 
Log by the person(s) authorized on the Delegation of Authority Log to perform that step.  
IP must be kept in a secure location under the control of the site investigator or 
authorized designee as recorded on the Delegation of Authority Log.  The Product 
Accountability Log and Delegation of Authority Log are to be maintained by the site 
and confirmed during monitoring visits.  The steps to be tracked include dates of receipt 
and dispensing, batch number, subject number, storage in refrigerator, and destruction if 
not administered to a subject.  The IP Administrator must ensure the correct batch 
number is administered to the correct subject. 
 
10. Study Procedures 
10.1. 
General Information 
Study information is collected on study-specific eCRFs by the site.  Study monitoring 
will occur at regular intervals to ensure the protection of subject rights and safety, data 
integrity and accuracy, and proper study conduct in compliance to the protocol and 
applicable regulations including 21 CFR 312 and ICH E6 GCPs.  Study visits and 
telephone assessments must occur with the window specified in Table 10-1; visits and 
calls out of window or missed are to be reported as protocol deviations. The study-
required procedures are to be conducted as shown in Table 10-1. 
Timely and complete follow-up visits will ensure the scientific integrity of the data is 
maintained and allow for continued oversight of subject safety.  


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 6.0; 08DEC2021 
  
   
 
 
 CONFIDENTIAL    
             
       
 
        Page 42 of 85 
 
Table 10-1 Schedule of Events 
Activity 
Screening 
(Enrollment) 
Baseline / 
Enema 
Administration 
(≤ 21 days from 
Screening) 
Follow-up 
Visits: 1- and 
8-Week (± 3 
days) 
Assessments1 
Follow-up 
Phone 
Assessment: 
Week 4 (± 3 
days) 
Follow-up 
Phone 
Assessment: 4 
and 6 months 
(± 14 days) 
Unscheduled 
Possible 
Recurrence 
Visit 
Second Enema 
Administration1 
(≤ 21 calendar 
days post Tx 
Failure) 
Second Enema Follow-
up Phone Assessment: 
1-, 4-, and 8-weeks (± 3 
days), and 6 months 
(± 14 days) 
Informed consent obtained 
X 
 
 
 
 
 
 
 
Demographics, medical history 
X 
 
 
 
 
 
 
 
Prescribe/continue antibiotics for CDI 
symptom control 
X 
 
 
 
 
 
 
 
Physical exam  
X 
 
 
 
 
 
 
 
Stool sent to Rebiotix by subjects for 
testing and archiving (optional) 
X 
 
X 
X 
X 
X 
 
X 
Central Lab CBC w/differential testing3 
X3 
X 
 
 
 
 
 
 
Central Lab CD4 testing 
X3 
 
 
 
 
 
 
 
Central Lab CMP & CRP testing 
X 
 
 
 
 
 
 
 
C. difficile testing4 
 
 
 
 
 
X4 
 
 
Central Lab stool and blood testing 
 
X 
 
 
 
 
 
 
Urine pregnancy testing performed at site 
(if applicable) 
X 
X 
 
 
 
 
X 
 
Cdiff32 Questionnaire 
X 
 
X 
 
X 
X 
 
 
Inclusion/exclusion criteria confirmed 
X 
X 
 
 
 
 
 
 
24-72hr washout period confirmed 
 
X 
 
 
 
 
X7 
 
Enema administered 
 
X 
 
 
 
 
X 
 
Product complaint (if applicable) 
 
X 
 
 
 
 
X 
 
CDI symptoms assessed 
 
X 
X 
X 
X 
X 
X 
X 
Vital signs assessed 
X 
X 
 
 
 
X 
X 
 
Weight 
X 
 
X 
X 
X 
 
 
X 
Subject Diary discussed/reviewed 
X 
X 
X5 
 
 
 
 
 
Employment status assessed 
X 
 
X6 
 
X 
 
 
 
Concomitant medications 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse events assessed 
 
X 
X 
X 
X 
X 
X 
X 
Solicited events assessed2 
 
X 
X2 
 
 
 
 
 
1 Documented treatment failures may receive a second RBX2660 enema.  
2 Solicited events are collected in the Subject Diary from the day of administration of the baseline enema until the day prior to the 1-week Follow-up visit. The Subject Diary is reviewed 
at the 1-week Follow-up visit.  Solicited events that increase in severity from Screening should be assessed for a possible adverse event. 
3 Exclusion criteria for absolute neutrophil count and CD4 should be assessed based on the blood samples collected at the Screening visit. 
4 Tested at the central laboratory. 
5 Subject Diary is reviewed only at the 1-week Follow-up visit. 
6 Collected at the 8-week follow-up visit only. 
7 If antibiotics were administered to manage CDI recurrence. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 43 of 85 
 
10.2. 
Informed Consent 
All subjects must sign the study-specific IRB/REB-approved Informed Consent/HIPAA 
Form; see Section 8.3.  The original signed Form is to be placed in the subject’s study 
file.  A copy of the signed Form is also to be given to the subject for their records. 
10.3. 
Subject Diary  
The Subject Diary serves as a tool for the subject to record pre- and post-treatment 
health and information.  The Subject Diary is reviewed for solicited event occurrence 
and severity, changes to medications, occurrence of adverse events, and possible 
recurrence of CDI.  The subject also documents changes in medications.  
At the Screening visit, subjects are provided a Subject Diary to complete each day until 
the day prior to the study enema (Baseline visit).  This may be up to 21 days.  The diary 
will be reviewed at the Baseline visit prior to enema administration.  
Prior to the subject leaving at the conclusion of the Baseline visit, the subject is 
instructed to continue completing the Subject Diary for each day until the 1-week office 
visit. 
The following information is entered into the study database:  
• solicited event severity 
• changes to medication 
• occurrence of adverse events   
10.4. 
Optional Stool Samples for Additional Testing by Rebiotix 
Subjects may agree (consent) to provide additional, optional stool samples to Rebiotix 
for research development activities.  Subjects consenting to the Optional Stool Sample 
collection are requested to provide stool samples directly to Rebiotix at the following 
time-points:  
• Screening (between the time of enrollment and prior to treatment) 
• at the time of the 1- and 8-week office visits  
• at the time of the 4-week, and at 4- and 6-month phone calls  
• at the time of possible treatment failure symptoms 
• at the 1-, 4-, and 8-weeks and 6-month phone calls after a second enema, 
if applicable 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 44 of 85 
 
Subjects collect the samples at home in pre-labeled containers given to them by the 
study team.  Rebiotix provides the study sites with kits containing all the materials for 
collecting and shipping the samples, including subject directions, container labels, and 
prepaid, pre-addressed mailing labels.  Samples are identified by the label on the 
container that contains only the subject’s study identification number and date/time of 
the sample; samples will not contain any personal information that would identify the 
subject.  Samples may be stored for approximately five years.  The stool samples will be 
used for research about the microorganisms in the human gut and the effects of 
microbiota restoration therapy on the gut microbiome. Some of the research will include 
testing for microorganisms (Clostridium difficile and vancomycin-resistant enterococci) 
both before and after receiving the study enema.  Failure to send in a sample does not 
result in a protocol deviation, however subjects should be reminded of this request.   
10.5. 
Screening Visit 
The following study activities/data will be collected/conducted at the Screening visit: 
• Subjects are told about the study and informed consent is obtained 
(enrollment) 
• Assign the subject number.   
o The format for subject number will include site code, followed by 
study-specific identifier, and 3-digit subject number assigned in 
sequential ascending order. For example: AAAOLS, RBX08-###.  
Where “AAA” is your study site’s code, and “###” is the subject’s 
number following a -001, -002, -003,… format. 
• Standard demographics: gender, ethnicity, date of birth, race 
• Relevant medical history, including comorbidity index variables (see 
Section 16)  
• CDI medical history documentation will be collected 
• Assess inclusion/exclusion criteria  
• Measure vital signs: height, weight, blood pressure, pulse, breathing rate 
and temperature  
• Physical exam (no genitourinary exam unless medically indicated) is 
performed to establish a study baseline health status (findings that can be 
attributed to the subject’s medical history):  
o General 
o HEENT (head, eyes, ears, nose and throat) 
o Cardiovascular 
o Gastrointestinal  


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 45 of 85 
 
o Musculoskeletal 
o Neurological 
• Blood samples are collected and analyzed at the central laboratory for:  
o CD4 count 
o CBC w/differential  
o Comprehensive metabolic panel (CMP): Sodium, potassium, 
chloride, BUN, creatinine, albumin, AST, ALT, alkaline 
phosphatase, bilirubin (direct, indirect and total), glucose  
o C-reactive protein (CRP)  
NOTE: the results of the absolute neutrophil count (ANC) and CD4 
tests must be confirmed ≥ 1000 cells/µL and ≥200/mm3, respectively 
• Onsite urine pregnancy test for subjects of child bearing potential   
• Complete the Cdiff32 health-related quality of life questionnaire 
completed by the subject (see Section 17) 
• Document concomitant medications taken within the last 30 days 
• Completion of the Subject Diary is explained and how to complete it is 
demonstrated; see Section 10.3   
• Record employment status 
• For subjects who consented to the Optional Stool Sample collection, 
remind them to obtain and ship a stool sample to Rebiotix anytime 
between their Screening visit and their Baseline visit dates 
10.6. 
Randomization 
There is no randomization in this study. 
10.7. 
Order IP/Study Drug 
Orders for IP/study drug are placed through the Medpace ClinTrak study database.  IP 
should be ordered approximately four (4) business days in advance of the planned IP 
administration date, if not earlier.  This timeframe is to accommodate the shipping 
schedule, and instructions for thawing which are located in the Instructions for Use.  
10.8. 
Baseline Visit and Study Treatment Administration 
IP/study drug should be ordered approximately four (4) business days in advance of the 
planned IP administration date, if not earlier. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 46 of 85 
 
The Baseline visit is performed on the day of the study treatment (IP) administration.  IP 
administration must occur within 21 days of the Screening visit.  Antibiotics for the 
control of CDI symptoms are continued until 24-72 hours before administration of the 
IP.  
The following study activities/data will be collected at the Baseline visit prior to IP 
administration: 
• Inclusion/exclusion criteria are confirmed including the following: 
o The control of symptoms during antibiotic use is confirmed by 
review of the subject diary (see Section 7.3.1) 
o Compliance to the washout period (discontinuation of the 
antibiotics for 24-72 hours prior to the Baseline visit) is confirmed 
 Stop date and time (AM/PM) of antibiotic  
• Central laboratory blood sample collection; see Table 10-2 for the list of 
tests.  NOTE: these results are not needed before proceeding to treatment 
per the protocol  
• Central laboratory stool sample collection; see Table 10-2 for the list of 
tests.  NOTE: the results are not needed before proceeding to treatment 
per the protocol  
• Onsite urine pregnancy test for subjects of child bearing potential 
• Assess vital signs: temperature, pulse, blood pressure, respiration 
• Changes to concomitant medications since the last visit 
• Review subject diary (see Section 10.3) 
• Assess recurrence of CDI  
• Assess for adverse events since enrollment 
• 
Date and time of the last bowel movement prior to the enema  
• Did the subject void his/her bladder prior to entering the administration 
room 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 47 of 85 
 
Table 10-2:  Baseline Testing Conducted by Central Laboratory 
Test Name 
Material Tested 
Norovirus  
Stool 
Rotavirus  
Adenovirus  
Enteric pathogens (Shigella, Salmonella, 
Campylobacter, sorbitol-negative E. coli., 
Aeromonas, Plesiomonas, Yersinia, and shiga toxins) 
Giardia antigen 
Cryptosporidium antigen 
Acid-fast staining (Cyclospora, Isospora) 
Ova and parasites 
Vancomycin-resistant enterococci (VRE) 
Methicillin-resistant Staphylococcus aureus (MRSA) 
Extended spectrum beta-lactamase (ESBL)-producing 
Enterobacteriaceae  
Vibrio 
Listeria 
Clostridium difficile 
Carbapenem-resistant Enterobacteriaceae Culture 
(CRE) 
CBC with Differential 
Blood 
HIV 
Hepatitis A (IgG) 
Hepatitis B Anti-Hepatitis B surface antigen 
Hepatitis C Antibody 
Treponema Antibody 
 
The following information is collected specific to the administration of the IP: 
• Enema clinical batch number 
• Enema administration start and end time 
• Enema administration status (successful; attempted, not completed; opened, not 
administered) 
• Subject position for enema 
o Length of time subject was in position after enema 
• Did the Rebiotix kit components perform as expected 
• Note whether the subject expelled or leaked any of the IP during the observation 
period 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 48 of 85 
 
o How long was the enema retained before the expulsion or leakage 
(minutes) 
o What was the estimated amount of enema that was expelled or leaked 
Following successful completion of the above listed items, IP is administered via enema 
per the Instructions for Use and standard site procedure; see Section 9.8.3.  Subjects 
remain at the site under supervision for at least one hour post-IP administration for vital 
sign assessment (temperature, heart rate, blood pressure, respiratory rate) about every 15 
minutes and observation.  If the subject’s vital signs do not return to the pre-
administration values ± 20%, assess the subject for a possible AE.   
All safety data collected are to be recorded and reported as required in Section 11.  
The subject is sent home after completion of study procedures including a review of the 
Subject Diary instructions, and is requested to call the study site if symptoms recur or at 
the onset of an adverse event.  
10.9. 
1-week In-Office Visit  
The 1-week follow-up visit is to occur within the window of ±3 days from the Baseline 
visit.  All safety data collected are to be recorded and reported as required in Section 11. 
The following study activities/data is collected at the 1-week follow-up visit: 
• Review of the subject diary for solicited events as defined in Section 11.4 
• Assess recurrence of CDI 
• Subject’s weight 
• Adverse event collection, including new onsets of obesity, metabolic 
syndrome, pre-diabetes, diabetes and/or autoimmune disorders 
• Cdiff32 health-related quality of life questionnaire completed by the 
subject 
• Changes to concomitant medications since the last visit 
• For subjects who consented to the Optional Stool Sample collection, 
remind the subject to collect and ship a stool sample to Rebiotix 
10.10. 
4-week Telephone Assessment  
This phone call must occur within the window of ±3 days (see Table 10-1); out of 
window or missed telephone assessments are to be reported as protocol deviations.  All 
safety data collected are to be recorded and reported as required in Section 11.   


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 49 of 85 
 
The following study activities/data is collected at the telephone assessment calls: 
• Assess recurrence of CDI 
• Subject’s weight, self-reported 
• Adverse event collection, including new onsets of obesity, metabolic 
syndrome, pre-diabetes, diabetes and/or autoimmune disorders 
• Changes to concomitant medications since the last visit 
• For subjects who consented to the Optional Stool Sample collection, 
remind the subject to collect and ship a stool sample to Rebiotix 
10.11. 
8-week In-Office Visit 
The 8-week follow-up visit is to occur within the window of ±3 days (see Table 10-1).  
All safety data collected are to be recorded and reported as required in Section 11. 
The following study activities/data is collected at the 8-week follow-up visit: 
• Assess Treatment Outcome and recurrence of CDI 
• Subject’s weight 
• Adverse event collection, including new onsets of obesity, metabolic 
syndrome, pre-diabetes, diabetes and/or autoimmune disorders 
• Changes to concomitant medications since the last visit 
• Cdiff32 health-related quality of life questionnaire completed by the 
subject 
• Record employment status 
• For subjects who consented to the Optional Stool Sample collection, 
remind the subject to collect and ship a stool sample to Rebiotix 
10.12. 
4- and 6- Month Telephone Assessments 
These phone calls must occur within the window of ±14 days (see Table 10-1).  All 
safety data collected are to be recorded and reported as required in Section 11.  Prior to 
the call, mail out the Cdiff32 health-related quality of life questionnaire to the subject for 
completion, including the return, addressed and stamped envelope. 
The following study activities/data will be collected at the telephone assessment calls: 
• Assess recurrence of CDI 
• Subject’s weight, self-reported 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 50 of 85 
 
• Adverse event collection, including new onsets of obesity, metabolic 
syndrome, pre-diabetes, diabetes and/or autoimmune disorders 
• Changes to concomitant medications since the last visit 
• Remind the subject to complete the Cdiff32 health-related quality of life 
questionnaire, if not received prior to the telephone visit. 
• Record employment status 
• For subjects who consented to the Optional Stool Sample collection, 
remind the subject to collect and ship a stool sample to Rebiotix 
The last phone call will occur 6 months after the date of the last administration of IP.   
10.13. 
Unscheduled Possible Recurrence Visit 
If CDI recurrence is suspected any time within 8 weeks of the last study enema due to 
new onset documentation of three or more unformed/loose (i.e., Bristol Stool Scale type 
6-7) stools within 24 or fewer consecutive hours for at least two consecutive days, 
possible treatment failure should be assessed.  An in-office visit should occur if a 
recurrence of CDI is suspected.  The subject must provide a fresh stool sample for 
shipment to the central laboratory to test for the presence of C. difficile.  
The following study activities/data will be collected at the Unscheduled Possible 
Recurrence visit: 
• Collect fresh stool sample to send to the central laboratory for analysis  
• Assess recurrence of CDI  
o Start date of symptoms, current symptoms, central laboratory 
testing result, source of episode (CDI recurrence, healthcare 
contagion, community contagion, or unknown), treatment(s) 
• Vital signs: temperature, pulse, blood pressure, respiration 
• Adverse event collection, including the new onsets of obesity, metabolic 
syndrome, pre-diabetes, diabetes and/or autoimmune disorders 
• Changes to concomitant medications since last visit 
• Cdiff32 health-related quality of life questionnaire 
• For subjects who consented to the Optional Stool Sample collection, 
remind the subject to collect and ship a stool sample to Rebiotix.     
 
 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 51 of 85 
 
Treatment failure (CDI recurrence) is defined as:  
• The presence of CDI diarrhea within 8 weeks of administration of a study 
enema, which includes a positive stool test for C. difficile as determined 
by the central laboratory. 
To ensure consistency across clinical sites for the determination of study failure, the 
central laboratory will perform the required C. DIFF QUIK CHEK COMPLETE® Test 
(QCC Test) rapid enzyme immunoassay test for glutamate dehydrogenase (GDH) and 
toxins A and B.  
In the case of suspected treatment failure where there is an immediate concern for 
subject safety, including the potential for serious adverse events, a test may be 
conducted at the site or other laboratory known to the site in addition to sending a 
sample to the central laboratory for testing.  In the event the test results from the central 
laboratory differ from that of a local laboratory, the results from the central laboratory 
will be used in determination of treatment failure and eligibility to receive a second 
treatment with RBX2660, instead of the other laboratory’s result. 
10.14. 
Second RBX2660 Treatment 
Subjects with a documented treatment failure meeting the protocol definition (Section 
7.3.6) after receipt of the first RBX2660 enema may be scheduled for administration of a 
second RBX2660 enema.  If antibiotics are given to control symptoms, a 24-72 hour 
washout period prior to administration of a second RBX2660 enema is required, 
however the second enema must be administered within 21 calendar days of failure 
determination.   
In order to receive the second treatment with RBX2660, a subject must have 
documentation of the following: 
• Meeting all treatment failure criteria as defined by the protocol (Section 
7.3.6) 
• Compliance to the washout period (discontinuation of antibiotics for 24-72 
hours prior to administration visit) is confirmed, if applicable  
• Negative urine-dipstick pregnancy test for subject of childbearing 
potential to confirm that they are not pregnant on the date of 
administration 
• Enema administration is to occur within 21 calendar days of failure 
determination 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 52 of 85 
 
 
The following study activities/data will be collected at this visit prior to IP 
administration: 
• Onsite urine pregnancy test for subjects of child bearing potential 
• Assess vital signs: temperature, pulse, blood pressure, respiration 
• Changes to concomitant medications since the last visit 
• Assess recurrence of CDI  
• Assess for adverse events since enrollment 
• 
Date and time of the last bowel movement prior to the enema  
• Did the subject void his/her bladder prior to entering the administration 
room 
 
Following successful completion of the above listed items, IP is administered via enema 
per the Instructions for Use and standard site procedure; see Section 9.8.3.   
The following information is collected specific to the administration of the IP: 
• Enema clinical batch number 
• Enema administration start and end time 
• Enema administration status (successful; attempted, not completed; opened, not 
administered) 
• Subject position for enema 
o Length of time subject was in position after enema 
• Did the Rebiotix kit components perform as expected 
• Note whether the subject expelled or leaked any of the IP during the observation 
period 
o How long was the enema retained before the expulsion or leakage 
(minutes) 
o What was the estimated amount of enema that was expelled or leaked 
Subjects remain at the site under supervision for at least one hour post-IP administration 
for vital sign assessment (temperature, heart rate, blood pressure, respiratory rate) about 
every 15 minutes and observation.  If the subject’s vital signs do not return to the 
Baseline visit’s (Section 10.8) pre-administration values ± 20%, assess the subject for a 
possible AE.   
All safety data collected are to be recorded and reported as required in Section 11.  


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 53 of 85 
 
If a subject receives a second RBX2660 enema, follow-up is completed via telephone 
assessment at 1-week, 4-weeks, 8-weeks, and 6 months per Section 10.14.1 after the 
second RBX2660 treatment. 
No additional treatments of RBX2660 beyond a second enema will be administered as 
part of this study for treatment failures. 
The study will be considered complete when all subjects have reached their 6-month 
follow-up after the last study enema received, including second enemas, or have exited, 
whichever is earlier.   
10.14.1. 
1-week, 4-weeks, 8-weeks, 6-month Telephone Assessment 
• Subject’s weight, self-reported 
• Adverse event collection, including new onsets of obesity, metabolic 
syndrome, pre-diabetes, diabetes and/or autoimmune disorders 
• Changes to concomitant medications since the last visit 
• For subjects who consented to the Optional Stool Sample collection, 
remind the subject to collect and ship a stool sample to Rebiotix 
10.15. 
Study Exit 
A Study Exit eCRF will be completed for each subject who is treated.  Data to be 
collected at this visit includes exit date and reason for study exit.  This visit may occur in 
conjunction with the 6-month Follow-Up visit for subjects who complete the study and 
do not have ongoing adverse events that have not stabilized. 
The following information will be collected on the Study Exit eCRF: 
• Exit date 
• Reason for study exit 
o Completed Study 
o Screen Failure 
o Withdrawal by subject 
o Study Terminated by Sponsor 
o Investigator withdrawal 
o Adverse Event 
o Death  
o Lost to Follow-Up 
o Other (to be specified) 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 54 of 85 
 
Additional data will be collected when the following occur: 
• Medication changes 
• Adverse Events 
10.16. 
Subject Withdrawal or Termination 
A subject’s study participation is considered complete once the 6-month telephone 
assessment is conducted after receiving the last study enema or the subject exits the 
study, whichever comes first.  A subject may withdraw at any time for any reason or be 
withdrawn from the study prematurely for the following reasons: 
• Withdrawal of consent by subject 
• Lost to follow-up 
• Failure to comply to study requirements 
• Termination of study by the sponsor 
• Death 
• Other (to be specified) 
The reason for withdrawal is recorded on the Study Exit eCRF.  In the event that a 
subject requests to withdraw from the study, every attempt should be made to have the 
subject provide an update on the current status of any adverse events and current 
medications.  If the subject has an ongoing adverse event deemed related to IP or enema 
procedure, recommend following the subject until the adverse event has resolved or 
stabilized prior to exiting the study. 
For a subject who is suspected of being lost-to-follow-up, a minimum of three attempts 
must be made to contact subjects using two different contact methods (e.g., telephone, 
email, text, and letter); one attempt must be a registered postal letter or traceable courier 
notice (e.g., FedEx Express) to the subject’s last known address.  The contact attempts 
and methods are to be recorded on the Study Exit eCRF.  The date to use for the subject 
as lost to follow-up is the date of last actual encounter with the subject, such as the last 
phone call contact or visit.   
Completion of a Study Exit eCRF is required for all treated subjects when they exit the 
study regardless of reason, including completion of all study requirements, visits and 
assessments.  Subjects who were determined to be screen failures or otherwise exited 
prior to receiving a dose of the study drug will also have a Study Exit eCRF completed. 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 55 of 85 
 
11. Assessment of Safety  
11.1. 
Adverse Event Management 
Adverse events (AE), which include clinical laboratory test variables, will be monitored 
and documented from the time of informed consent.  Subjects should be instructed to 
report any AE that they experience to the investigator.  Investigators should make an 
assessment for AEs at each visit and record the event on the appropriate eCRF. 
Wherever possible, a specific disease or syndrome rather than individual associated 
signs and symptoms should be identified by the investigator and recorded on the eCRF.  
However, if an observed or reported sign or symptom is not considered a component of 
a specific disease or syndrome by the investigator, it should be recorded as a separate 
adverse event on the eCRF.  Additionally, the condition that led to a medical or surgical 
procedure (e.g., surgery, endoscopy, tooth extraction, or transfusion) should be recorded 
as an AE, not the procedure.  
Any medical condition already present at Screening should not be reported as an AE 
unless the medical condition or signs or symptoms present at Screening change in 
severity or seriousness at any time during the study.  In this case, it should be reported as 
an AE. 
Clinically significant abnormal laboratory or other examination (e.g., electrocardiogram) 
findings that are detected during the study or are present at Screening and significantly 
worsen during the study should be assessed for an AE.  The investigator will exercise 
their medical and scientific judgment in deciding whether an abnormal laboratory 
finding or other abnormal assessment is clinically significant.  Clinically significant 
abnormal laboratory values occurring during the clinical study will be followed until 
repeat tests return to normal, stabilize, or are no longer clinically significant.  Any 
abnormal test that is determined to be an error does not require reporting as an AE. 
For all CDI recurrences, information is recorded on the Follow-up eCRF and applicable 
CDI eCRF.  Recurrence of CDI is not to be reported as an AE unless hospitalization ≥ 
24 hours is required as part of treatment.  If hospitalization ≥ 24 hours is required, the 
event qualifies as an AE and is to be reported as an SAE (see Section 11.14 for sponsor 
reporting requirements). 
AEs should be followed until the event resolves or the subject exits the study.  Chronic 
condition is defined as a condition lasting > 3 months.  


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 56 of 85 
 
11.2. 
AE Definitions 
• Adverse event:  an adverse event (AE) is any untoward medical occurrence in 
a clinical investigation subject associated with the use of IP, which does not 
necessarily have a causal relationship with the treatment.  An AE can 
therefore be any unfavorable and/or unintended sign (including an abnormal 
laboratory finding), symptom, or disease temporally associated with the use of 
IP.   
o All AEs, including observed or volunteered problems, 
complaints, or symptoms are to be recorded on the eCRF 
within ten (10) business days of site awareness. 
• Adverse reaction:   All noxious and unintended responses to IP should be 
considered an adverse reaction. “Responses” to IP means that a causal 
relationship between IP and an AE is at least a reasonable possibility, i.e., the 
relationship cannot be ruled out.   
• Serious adverse event (SAE): An AE or adverse reaction is considered serious 
if, in the view of either the investigator, Medical Monitor or sponsor, it results 
in any of the following outcomes: 
o Death 
o Life-threatening adverse event 
NOTE: An adverse event or adverse reaction is considered “life-
threatening” if, in view of either the investigator or Sponsor, its 
occurrence places the subject at immediate risk of death.  It does 
not include an event that, had it occurred in a more severe form, 
might have caused death. 
o Hospitalization ≥ 24 hours or prolongation of an existing 
hospitalization 
NOTE: Any hospital admission with at least one overnight stay will 
be considered an inpatient hospitalization.  An emergency room 
visit without hospital admission will not be recorded as a serious 
adverse event (SAE) under this criterion, nor will hospitalization 
for a procedure scheduled or planned before signing of informed 
consent.  However, unexpected complications and/or prolongation 
of hospitalization that occur during elective surgery should be 
recorded as AEs and assessed for seriousness.  Admission to the 
hospital for social or situational reasons (i.e., no place to stay, live 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 57 of 85 
 
too far away to come for hospital visits) will not be considered 
inpatient hospitalizations. 
o Persistent or significant incapacity or substantial disruption of 
the ability to conduct normal life functions. 
o Congenital anomaly/birth defect. 
o Important medical event 
NOTE: Important medical events that may not result in death, be 
life-threatening, or do require hospitalization may be considered 
serious when, based upon appropriate medical judgment, they may 
jeopardize the subject and may require medical or surgical 
intervention to prevent one of the outcomes above.  Examples of 
such medical events include allergic bronchospasm requiring 
intensive treatment in an emergency room or at home, blood 
dyscrasias or convulsions that do not result in inpatient 
hospitalizations, or the development of drug dependency. 
• Unexpected Adverse Reaction: An adverse reaction, the nature or severity of 
which is not consistent with the applicable product information. 
• Unexpected adverse event or unexpected suspected adverse reaction: An AE 
or suspected adverse reaction is considered “unexpected” if it is not listed in 
the Investigator’s Brochure or is not listed at the specificity or severity that 
has been observed. 
11.3. 
Anticipated Adverse Events 
The following is list of anticipated AEs that may or may not be causally related to IP, 
the enema procedure, or CDI:  
• gas (flatulence) 
• belching 
• abdominal distension or bloating 
• increased diarrhea 
• abdominal cramping or pain 
• constipation 
• colitis 
• fever ≥ 37.8° C (100.0°F) 
• fatigue 
• chills 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 58 of 85 
 
• transmission of disease from the donor to recipient 
• rectal irritation or pain 
• rectal bleeding 
• nausea 
• vomiting 
• hypotension 
• puncture of the intestine 
11.4. 
Solicited Events 
The following list of anticipated events are solicited from subjects via the Subject Diary:   
• gas (flatulence) 
• abdominal distension or bloating 
• rectal irritation or pain 
• chills/severe shivering 
• abdominal pain or cramping 
• increased diarrhea 
• constipation 
• rectal bleeding 
• nausea 
• vomiting 
• fever ≥ 37.8° C (100.0°F) 
Through the completion of the Subject Diary, subjects are asked specific questions 
regarding frequency and severity of the solicited AEs.   
11.5. 
Preexisting Condition 
A preexisting condition, including abnormal physical exam findings, is one that is 
present at the start of the study and is to be recorded at the time of the Screening visit.  A 
preexisting condition is only to be recorded as an adverse event if the frequency, 
intensity or the character of the condition worsens during study participation. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 59 of 85 
 
11.6. 
Serious Adverse Event Reporting – Procedures for Investigators 
11.6.1. Initial Reports 
All SAEs occurring from the time of informed consent until 6 months after 
administration of the last study enema of IP must be reported to Medpace Clinical Safety 
within 24 hours of the knowledge of the occurrence (this refers to any AE that meets 
any of the aforementioned serious criteria).   
To report the SAE, complete the SAE form electronically in the electronic data capture 
(EDC) system for the study.  When the form is completed, Medpace Safety personnel 
will be notified electronically and will retrieve the form.  If the event meets serious 
criteria and it is not possible to access the EDC system, send an email to Medpace Safety 
at medpace-safetynotification@medpace.com or call the Medpace SAE hotline (phone 
number listed below), and fax the completed paper SAE form to Medpace (fax number 
listed below) within 24 hours of awareness.  When the EDC system becomes available, 
the SAE information must be entered within 24 hours of the system becoming available. 
Safety Contact Information: 
Medpace Clinical Safety 
 
Medpace SAE hotline: 
 
 
 
11.6.2. Follow-Up Reports 
The investigator must continue to follow the subject until the SAE has subsided or until 
the condition becomes chronic in nature, stabilizes (in the case of persistent impairment) 
or the subject dies.  Chronic is defined as a condition lasting >3 months.  
Within 24 hours of receipt of follow-up information, the investigator must update the 
SAE form electronically in the EDC system for the study and submit any supporting 
documentation (e.g., subject discharge summary or autopsy reports) to Medpace Clinical 
Safety via fax or e-mail.  If it is not possible to access the EDC system, refer to the 
procedures outlined above for initial reporting of SAEs.  
11.7. 
Grading Event Severity 
Identified, subject-reported and unsolicited AEs are to be graded, according to severity, 
by the site investigator.  For this classification of events, severity is not the same as 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 60 of 85 
 
seriousness, which is defined in Section 11.1.  Severity is an indication of the intensity 
of a specific event (e.g., mild, moderate or severe).  Classification of an event as serious 
relates to an event’s outcome or intervention criteria and is usually associated with 
events that pose a threat to a subject’s life or functioning.  An event can be severe but 
not serious, such as a migraine.   
Using the definitions in Table 11-1, the site investigator will categorize the severity of a 
solicited or unsolicited event on the AE eCRF.  If a particular event is not listed on this 
table, the NIH/NCI Common Terminology Criteria for Adverse Events found at online at 
the following address may be utilized.  
https://ctep.cancer.gov/protocolDevelopment/electronic_applications/docs/CTCAE_v5_
Quick_Reference_8.5x11.pdf  
Table 11-1:  Severity Grading Table* 
Parameter 
Grade1: Mild 
Grade 2: Moderate Grade 3: Severe 
Grade 4: 
Potentially Life-
threatening 
Flatulence 
(gas) 
Symptoms causing 
no or minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
greater than 
minimal 
interference with 
usual social and 
functional activities  
NA 
 
NA 
Belching 
(burping) 
Symptoms causing 
no or minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
greater than 
minimal 
interference with 
usual social and 
functional activities  
NA 
 
NA 
Abdominal 
distension or 
bloating 
Symptoms causing 
no or minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
greater than 
minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
inability to perform 
usual social and 
functional activities  
 
NA 
Increased 
diarrhea 
Increase of ≤ 3 
stools over baseline 
per 24-hour period  
 
Increase of 4 – 6 
stools over baseline 
per 24-hour period  
 
Bloody diarrhea if 
not present at 
baseline OR increase 
of ≥ 7 stools over 
baseline per 24-hour 
period OR IV fluid 
replacement 
indicated if not 
indicated at baseline 
Life-threatening 
consequences, 
e.g., hypotensive 
shock 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 61 of 85 
 
Parameter 
Grade1: Mild 
Grade 2: Moderate Grade 3: Severe 
Grade 4: 
Potentially Life-
threatening 
Abdominal 
cramping/pain 
Discomfort/pain 
causing no or 
minimal 
interference with 
usual social and 
functional activities  
 
Discomfort/pain 
causing greater than 
minimal 
interference with 
usual social and 
functional activities  
Discomfort/pain 
causing inability to 
perform usual social 
and functional 
activities  
 
Disabling pain 
causing inability 
to perform basic 
self-care OR 
inpatient 
hospitalization ≥ 
24 hours 
Constipation 
Occasional or 
intermittent 
symptoms, 
occasional use of 
stool softeners, 
laxatives, dietary 
modifications or 
enema 
Persistent symptoms 
with regular use of 
laxatives or enemas 
indicated 
Symptoms causing 
inability to perform 
usual social and/or 
functional activities 
Life-threatening 
consequences, 
e.g., obstruction, 
toxic megacolon 
Colitis 
No symptoms, 
regardless of 
pathologic or 
radiographic 
evidence of 
inflammation 
Abdominal pain, 
mucus or blood in 
the stool 
Abdominal pain, 
fever, change in 
bowel habits with 
ileus; peritoneal 
signs 
Life-threatening 
consequences, 
e.g., perforation, 
bleeding, 
ischemia, 
necrosis, toxic 
megacolon 
Fever 
37.8 – 38.6°C 
(100.0 – 101.5° F)  
38.7 – 39.3°C 
(101.6 – 102.8° F)   
39.4 – 40.5°C 
(102.9 – 104.9° F)  
> 40.5°C 
(104.9° F)  
Fatigue/ 
malaise 
Symptoms causing 
no or minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
greater than 
minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
inability to perform 
usual social and 
functional activities  
Incapacitating 
fatigue/malaise 
symptoms causing 
inability to 
perform basic 
self-care functions 
Ch0ills 
Symptoms causing 
no or minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
greater than 
minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
inability to perform 
usual social and 
functional activities  
NA 
Rectal 
discomfort or 
irritation 
No symptoms or 
symptoms not 
requiring medical 
intervention 
Symptomatic with 
medical intervention 
(topical medications 
/ treatments) 
indicated 
Symptoms causing 
inability to perform 
usual social and 
functional activities 
or requiring medical 
intervention other 
than topical 
medications / 
treatments 
NA 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 62 of 85 
 
Parameter 
Grade1: Mild 
Grade 2: Moderate Grade 3: Severe 
Grade 4: 
Potentially Life-
threatening 
Rectal 
bleeding 
Mild or intermittent 
without transfusion 
Persistent without 
transfusion 
Requires transfusion 
Life-threatening 
consequences 
Nausea 
Transient (≤ 24 
hours) or 
intermittent nausea 
with no or minimal 
interference with 
oral intake 
Persistent nausea 
resulting in 
decreased intake for 
24-48 hours 
Persistent nausea 
resulting in 
decreased intake > 48 
hours OR aggressive 
rehydration 
indicated, e.g., IV 
fluids 
Life-threatening 
consequence, e.g., 
hypotensive shock 
Vomiting 
Transient (≤ 24 
hours) or 
intermittent 
vomiting with no or 
minimal 
interference with 
oral intake 
Frequent episodes 
of vomiting with no 
or mild dehydration 
Persistent vomiting 
resulting in 
orthostatic 
hypotension OR 
aggressive 
rehydration 
indicated, e.g., IV 
fluids  
Life-threatening 
consequence, e.g., 
hypotensive shock 
Hypotension 
NA 
Symptomatic, 
corrected with oral 
fluid replacement 
 
Symptomatic, IV 
fluids indicated 
 
Shock requiring 
use of 
vasopressors or 
mechanical 
assistance to 
maintain blood 
pressure 
Adverse event 
not identified 
elsewhere in 
this table 
Symptoms causing 
no or minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
greater than 
minimal 
interference with 
usual social and 
functional activities  
Symptoms causing 
inability to perform 
usual social and 
functional activities  
Symptoms 
causing inability 
to perform basic 
self-care functions 
OR medical or 
operative 
intervention 
indicated to 
prevent permanent 
impairment, 
persistent 
disability, or death  
*Adapted from Division of AIDS Table for Grading of Severity of Adult and Pediatric Adverse Events and 
Addendum 3: Rectal Grading Table for Use in Microbicide Studies; May 2012. 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 63 of 85 
 
11.8. 
Causality 
For all adverse events, the investigator must pursue and obtain adequate information to 
determine the outcome of the adverse event and to assess whether the AE meets the 
criteria for classification as an SAE, serious suspected adverse reaction, suspected 
adverse reaction, unexpected AE, or unexpected suspected adverse reaction.  For all 
AEs, sufficient information should be obtained by the investigator to determine the 
causality of the AE.  For AEs with a causal relationship to the IP or the enema 
procedure, follow-up by the investigator is required until the event or its sequelae 
resolve or stabilize at a level acceptable to the investigator. 
The investigator will make a causality assessment for all AEs and decide whether there 
is a reasonable possibility that the AE may have been caused by the study product or 
procedure, including an assessment of biologic plausibility, presence or absence of 
alternative causal explanations (such as continuation or exacerbation of the subject’s 
recurrent CDI symptoms), and temporal relationship to product administration and/or the 
procedure.  Relatedness to RBX2660 or the enema procedure is defined as: 
• Unrelated: The event is due to an underlying or concurrent illness or 
effect of concomitant therapy and is not related to the study product or 
procedure (e.g., has no temporal relationship to study product or 
procedure, or has a much more likely alternative etiology) 
• Possible: There is some temporal relationship between the event and the 
administration of the study product or procedure, though the event could 
also be explained by the subject’s medical condition or other therapies. 
• Probable: The temporal relationship between the event and administration 
of the study product or procedure is suggestive, and the event is unlikely 
to be explained by the subjects’ medical condition or other therapies 
alone.  
• Definite: The event follows a reasonable temporal sequence from 
administration of the study product or procedure, follows a known or 
suspected response pattern to the study product and/or procedure, 
improves upon stopping the study product, and reappears upon repeated 
exposure, if that occurs. 
If an investigator is unsure about whether to report a finding as an AE, they are 
encouraged to enter the finding as an AE into the study database.   


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 64 of 85 
 
11.9. 
Pregnancy Reporting 
If the subject or partner of a subject participating in the study becomes pregnant during 
the study after IP administration, the investigator should report the pregnancy to 
Medpace Clinical Safety within 24 hours of being notified.  Medpace Clinical Safety 
will then forward the Exposure In Utero form to the investigator for completion.  
The subject or partner should be followed by the investigator until completion of the 
pregnancy.  If the pregnancy ends for any reason before the anticipated date, the 
investigator should notify Medpace Clinical Safety.  At the completion of the pregnancy, 
the investigator will document the outcome of the pregnancy.  If the outcome of the 
pregnancy meets the criteria for immediate classification as an SAE (i.e., postpartum 
complication, spontaneous abortion, stillbirth, neonatal death, or congenital anomaly), 
the investigator should follow the procedures for reporting an SAE. 
11.10. 
Medical Monitor 
An independent Medical Monitor reviews all SAEs and other events reported by the site 
as related to the investigational product or enema procedure to provide an objective, 
qualified judgment of the events.  The Medical Monitor is a physician not participating 
as an investigator in this study.  The Medical Monitor has the responsibility to review 
and evaluate the information relevant to product safety throughout the development and 
implementation of the protocol.  The Medical Monitor performs the following functions: 
• Reviews SAEs and other AEs as requested; 
• Reviews the study protocol and Investigator’s Brochure for adequacy of safety 
oversight; 
• Confers with site investigators, DSMB and the Rebiotix Clinical Department 
as applicable regarding potential safety concerns; 
• Provides medical surveillance and provides appropriate recommendations for 
the conduct of the study as needed. 
Details of the Medical Monitor activities and expectations will be documented in a 
Safety Management Plan. 
11.11. 
Data and Safety Monitoring Board (DSMB) 
The DSMB will consist of at least two physicians specializing in infectious diseases or 
gastroenterology who have experience managing subjects with recurrent CDI and are not 
investigators in the study.  A biostatistician who is not involved with study design or 
analyses may assist the DSMB.  The DSMB will operate in accordance with applicable 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 65 of 85 
 
sections of the FDA Guidance for Clinical Trial Sponsors Establishment and Operation 
of Clinical Trial Data Monitoring Committees.   
Details of the DSMB logistics, activity and responsibilities will be included in a DSMB 
charter.  General responsibilities include oversight of subject safety through data review 
and assessment of trends.  This includes the ability to stop the study based on protocol-
defined stopping rules.  Additionally, the DSMB may provide an independent review of 
the efficacy outcome to ensure the benefits of providing this treatment to subjects 
outweighs the risks.   
11.12. 
Endpoint Adjudication Committee (EAC) 
The EAC will provide independent adjudication of treatment success or failure that will 
be used for study analysis and reporting purposes.  The EAC will be comprised of three 
physicians specializing in infectious diseases or gastroenterology who have experience 
managing subjects with recurrent CDI and are not investigators in the study.  Details of 
the EAC logistics, activity and responsibilities will be included in an EAC charter.   
11.13. 
Study Stopping Rules for Safety 
Rebiotix will oversee review of all AEs reported during the study to observe for trends 
and unanticipated events, either in severity, seriousness or incidence, and to assess if a 
study stopping rule may be triggered.  AE review includes the event description, onset 
date in relation to the treatment date, and the investigator’s determination of causal 
relatedness to IP, the enema procedure, and pre-existing condition, as well as rating the 
event’s severity and seriousness.  Additionally, the Medical Monitor assessment of 
seriousness and causality will be provided and reviewed as it may be different from the 
site investigator report of the event.  Anticipated AEs may trigger the study stopping 
rules. 
The DSMB will determine whether enrollment should be paused, the study terminated, 
or other actions taken based on their assessment that: 
a) There is probable cause that IP or enema procedure (e.g., due to 
transfer from an RBX2660 donor) contributed to a pathogenic 
intestinal infection in the stool of any subject, or 
b) Any events of major significance such as death or other serious 
outcome for which a causal connection with the IP is plausible and 
represents an excess of the important adverse event(s). 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 66 of 85 
 
To support the DSMB assessment, the Rebiotix Operations Department may be asked to 
review the donor history and batch processing/release records for the product unit(s) 
administered in these cases, and forward its report to the DSMB Chair for review.  The 
DSMB Chair will review the Operations Department report.  If probable cause is 
suspected, the DSMB Chair will convene the entire DSMB for event review.   
Upon the DSMB’s determination of action, the Chair will notify Rebiotix, who will 
notify the study sites.  
If enrollment is stopped, Rebiotix and the study sites will assess for the occurrence of 
similar events, and evaluate IP and study records for possible root cause(s).  Enrollment 
may be re-started upon further review and approval from the DSMB.  As appropriate, 
the DSMB may recommend study termination or measures short of termination with the 
objective of reducing the risk of AEs.   
11.14. 
Sponsor Reporting of Adverse Events 
The sponsor will report all relevant information about suspected unexpected serious 
adverse reactions that are fatal or life-threatening as soon as possible to the FDA & 
Health Canada, and in any case no later than seven (7) days after knowledge by the 
sponsor of such a case, and that relevant follow-up information will subsequently be 
communicated within an additional eight (8) days.  
All other suspected unexpected serious adverse reactions will be reported to the FDA as 
soon as possible but within a maximum of 15 days of first knowledge by the sponsor.  
The sponsor will also inform all investigators as required.  
11.14.1. 
Timeline for Reporting Requirements 
The following describes the expedited safety reporting requirements by timeline for 
reporting and associated type of event: 
• Within 7 calendar days of event discovery by Rebiotix 
Rebiotix will notify FDA and Health Canada of any unexpected fatal or life-threatening 
suspected adverse reaction as soon as possible but in no case later than seven (7) 
calendar days after the sponsor's initial receipt of the information.  
• Within 15 calendar days of event discovery by Rebiotix  
The AE must meet all three of these criteria for expedited reporting. Any study event 
that is: 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 67 of 85 
 
• suspected adverse reaction 
• serious 
• unexpected 
11.14.2. 
Additional Reporting Requirements 
The sponsor will identify in IND safety reports all previous reports concerning similar 
AEs and analyze the significance of the current event in light of the previous reports. 
11.14.3. 
Reporting AEs to FDA and Health Canada 
Rebiotix will report AEs to FDA and Health Canada as required by applicable 
regulations.  All AEs will be reported in the annual and final clinical study reports.   
 
12. Sample Size and Statistical Considerations 
This study has a Statistical Analysis Plan which contains complete details of the 
statistical methodology and analyses that will be employed for this study.  A final 
analysis of safety and efficacy results will be analyzed and reported in a final report after 
the last subject has completed the 6-month follow-up visit for their study treatment, 
including 6-month follow-up after a second RBX2660 study treatment, if applicable.   
12.1. 
Sample Size 
The purpose of this study is to assess the safety and tolerability of RBX2660 in a 
recurrent CDI population that is broader and more inclusive than that included in prior 
studies using RBX2660.  In order to continue to collect prospective safety information 
and allow open-label treatment access to a broad population of patients, up to 750 
subjects will be treated with RBX2660. 
Subjects who have signed informed consent forms but do not meet all eligibility criteria 
will be considered screen failures.  Subjects who withdraw for any reason prior to 
administration of the enema will be replaced without counting toward the sample size 
treatment cap of 750 subjects. 
12.2. 
Assessment of Safety and Tolerability 
Assessment of the primary safety objective and other safety objectives will be performed 
on all subjects exposed to RBX2660 (Safety Population) and will include descriptive 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 68 of 85 
 
statistics.  Additional sub-analyses of safety data may be performed on sub-populations 
(e.g., subjects with irritable bowel disease or irritable bowel syndrome).   
12.3. 
Assessment of Efficacy, Secondary Objectives 
Assessment of secondary objectives will include descriptive statistics and be performed 
on pre-defined analysis populations including Intent-to-Treat (ITT), modified Intent-to-
Treat (mITT) and Per-Protocol (PP).  Additional sub-analyses of safety data may be 
performed on sub-populations.   
Secondary Efficacy Endpoints:   
1. Recurrence of CDI within 8 weeks of treatment. 
Recurrence of CDI after 8 weeks from completion of the study treatment is considered a 
new CDI.  
The efficacy parameter used to determine treatment success is defined as the absence of 
CDI diarrhea through 8 weeks after completing a study treatment.  Efficacy assessments 
will occur at each scheduled contact: 1-, 4- and 8-weeks. 
2. Loss of sustained clinical response through 6 months after treatment 
Sustained clinical response is defined as treatment success of the presenting CDI 
recurrence and no new CDI episodes through 6 months after completing a study 
treatment.  Efficacy assessments will occur at each scheduled contact: 4 and 6 months. 
12.3.1. Analysis Population definitions 
12.3.1.1. Safety Population 
The safety population (SP) is defined as the population of subjects who had any 
treatment attempted or completed.  The safety population will be used in analysis of all 
safety endpoints including the primary endpoint. 
12.3.1.2. Intent-to-Treat Population 
The ITT population is defined as all subjects enrolled.   


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 69 of 85 
 
12.3.1.3. Modified Intent-to-Treat Population 
Analysis of the efficacy endpoints will use the modified Intent-to-Treat (mITT) 
population as a primary analysis population.  The mITT population is defined as all 
subjects who successfully received treatment but excluding;  
• subjects in whom treatment was attempted but not completed and;  
• subjects who discontinue from the study prior to evaluation of treatment 
failure/success for the primary endpoint if the reason for exit is not related to 
CDI symptoms.  Reason for exit will be captured on the exit form to allow for 
identification of such subjects.  Examples of reasons unrelated to CDI 
symptoms may include: 
 Withdrawal of consent 
 Death unrelated to CDI 
12.3.1.4. Per-Protocol Population 
The per-protocol (PP) population will consist of all subjects who successfully received 
treatment analyzed according to the treatment they received, excluding; 
• Subjects who have documented protocol deviations to inclusion or exclusion 
criteria. 
• Subjects who exited prior to the 8-week efficacy evaluation if the reason for 
exit was not related to CDI symptoms in the same manner as the mITT 
population.  
 
 
 
13. Study Administration 
13.1. 
Institutional Review Board / Research Ethics Board Approval 
The protocol, Informed Consent Form/HIPAA Form must be reviewed and approved by 
the respective IRB/REB and Rebiotix before subject recruitment and enrollment begins.   
Prior to subject enrollment, a signed copy of the IRB/REB approval letter addressed to 
the investigator and a full copy of the IRB/REB-approved Informed Consent 
Form/HIPAA Form must be submitted to Rebiotix, certifying study approval. 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 70 of 85 
 
Investigators are responsible for submitting and obtaining initial approval and 
continuing approval from the IRB/REB and forwarding copies of the approval letters to 
Rebiotix.  The approval letters are to be kept in the Trial Master File (TMF) designated 
for this study.   
13.1.1. US Sites 
Investigators are responsible for submitting and obtaining initial approval and 
continuing approval from the IRB and forwarding copies of the approval letters to 
Rebiotix.  The approval letters are to be kept in the Trial Master File (TMF) designated 
for this study.   
The investigator will notify the Rebiotix study manager within five (5) business days of 
withdrawal of IRB approval.  
Institutional Review Boards will operate in accordance to 21 CFR 56 and their own 
standard operating procedures. 
13.1.2. Canadian Sites 
Prior to subject enrollment, a signed copy of the REB approval letter addressed to the 
investigator, a full copy of the REB-approved Informed Consent Form, and completed 
Research Ethics Board Attestation must be submitted to Mapi Group, the Agent for 
Rebiotix in Canada, and to Rebiotix.  Investigators are responsible for submitting and 
obtaining initial approval and continuing approval from the REB and forwarding copies 
of the approval letters to Rebiotix.  Rebiotix will forward copies to Mapi Group.  The 
approval letters are to be kept in the Trial Master File (TMF) designated for this study.   
The investigator will notify Rebiotix within five (5) business days of withdrawal of REB 
approval.  Rebiotix will notify Mapi Group. 
REBs will operate in compliance with Health Canada regulations and their own standard 
operating procedures. 
13.2. 
Form 1572 and Financial Disclosure 
The principal investigator at each site (US and Canada) will complete and return a 
study-specific Form 1572 to the sponsor before beginning the study, as required by 
federal regulations.  The investigator agrees to be responsible for conducting the 
investigational study in accordance with the protocol, applicable FDA regulations 
including reporting and record-keeping requirements, GCPs, local IRB/REB 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 71 of 85 
 
requirements, and controlling dispensation and administration of RBX2660.  In addition, 
the investigator is responsible for ensuring that informed consent is obtained from each 
subject prior to participating in the study, as well as protecting the rights, safety and 
welfare of participating subjects. 
Individuals listed in Section 6 of Form 1572 are required to sign a Financial Disclosure 
form that certifies the individual and their immediate family’s financial interest in 
Rebiotix and study outcomes.  Investigators must inform Rebiotix of any changes to the 
information documented on the Financial Disclosure form throughout the course of the 
study and for a period of one year following completion of the study.  In the event of a 
change in study personnel, the site may need to complete and submit a new Form 1572 
to Rebiotix within 60 days of the change.   
13.2.1. Canadian Sites:  Qualified Investigator Undertaking Form 
The principal investigator(s) at each Canada site will complete and return the Qualified 
Investigator Undertaking (QIU) Form to Rebiotix before beginning the study, as 
required by Health Canada.  Rebiotix will forward the QIU to Mapi Group.  The 
investigator agrees to be responsible for conducting the investigational study in 
accordance with the protocol, applicable Health Canada regulations including reporting 
and record-keeping requirements, GCPs, local REB requirements, and controlling 
dispensation and administration of RBX2660.  In addition, the investigator is responsible 
for ensuring that informed consent is obtained from each subject prior to participating in 
the study, as well as protecting the rights, safety and welfare of participating subjects. 
13.3. 
Subject Confidentiality 
All information and data sent to Rebiotix, and/or its designees concerning subjects and 
their participation in this study are considered confidential by Rebiotix and its designees 
(subcontractors or contract research organization).  Only authorized Rebiotix personnel 
or approved contracted agents of Rebiotix have access to some portions of these 
confidential files and will act in accordance with applicable regulations.  The IRBs, 
REBs, FDA and Health Canada also have the right to inspect and copy all records 
pertinent to this study.  All data used in the reporting of the study will eliminate 
identifiable references to the subjects as much as possible.   
13.4. 
Study Oversight 
Clinical personnel at Rebiotix have knowledge of Good Clinical Practices, pertinent 
laws and regulations, and documented training in standard operating procedures 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 72 of 85 
 
pertaining to study management and monitoring and will provide study oversight.  
Rebiotix can be contacted at: 
Rebiotix Inc 
2660 Patton Road 
Roseville, MN 55113 
Phone: 651-705-8770 
13.5. 
Study Site Qualification 
Investigational center qualification visits or phone calls will be conducted by Rebiotix 
prior to acceptance of a site into this study.  The site qualification visit or phone call will 
be scheduled to include time with the study investigator and study coordinator.  Areas of 
discussion include a review of personnel training, investigator qualifications, IP 
Administrator qualifications, adequacy of potential subject pool, FDA- or Health 
Canada-regulated study experience, this study’s specific requirements for procedures 
and equipment, and a review of staffing availability and appropriateness.  A written 
report of the qualification call/visit will be generated by the sponsor representative who 
conducts the call/visit.  Resolution of any concerns and/or completion of any appropriate 
study activities identified during the qualification process will be documented and 
submitted to the study investigator.   
13.6. 
Investigator / Site Training 
The sponsor will provide appropriate training prior to study initiation to each 
investigator, an IP Administrator, and study coordinator(s) at each site; other site 
personnel who will be involved in the study may be trained by the sponsor staff or the 
trained investigator.  Training will address topics including ordering, secure storage and 
administration procedures, Subject Diary instructions, follow-up visit and phone call 
requirements, adverse event reporting, and accurate data collection.  Training will 
include a detailed review of the protocol, eCRF completion, study-specific procedures, 
monitoring logistics, and regulatory requirements as applicable for the study roles.  
13.7. 
Data Management 
Electronic case report forms specifically created for this study will be used to collect 
study data.  The study investigator or designee at each site is responsible for recording 
all data onto the study eCRFs.  The investigator must review and electronically sign all 
eCRFs as instructed; these responsibilities cannot be delegated to another person.  


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 73 of 85 
 
Ongoing data review will be performed according to the study-specific Data 
Management Plan. 
13.8. 
Monitoring 
This study is monitored according to the study-specific Clinical Monitoring Plan.  The 
investigator must allocate adequate time for such monitoring activities.  The investigator 
must also ensure that the monitor or other compliance or quality assurance reviewers are 
given access to all study-related documents and study-related facilities (e.g., pharmacy, 
diagnostic laboratory), and has adequate space to conduct the monitoring visit.  Study 
monitors and their activities are managed by Clinical Management or qualified designee; 
see Section 13.4.  Study monitors will follow requirements as documented in monitoring 
procedures and the study-specific Monitoring Plan. 
13.9. 
Direct Access to Source Data/Documents 
The investigator is expected to facilitate study-related monitoring, audits, and 
inspections by the IRB/REB, sponsor and sponsor representatives, FDA, and Health 
Canada of all study-related documents including direct access to original source 
documents such as medical records and lab results, regulatory documents, study data, 
etc.  The investigator will ensure access for the inspection of applicable study-related 
facilities (e.g., pharmacy, laboratory, exam rooms). 
Participation as a study investigator and study site in this study implies acceptance and 
support of inspections by FDA, Health Canada and/or Rebiotix or its designee(s). 
13.10. 
Investigator Responsibilities 
The investigator is responsible for ensuring that the study is conducted according to the 
protocol, applicable FDA or Health Canada regulations for investigational new drugs, 
HIPAA (US only), GCPs and local IRB/REB requirements.  Specific responsibilities are 
listed in this protocol.  
Site study records and reports are kept in the Investigator Study File (ISF).  Records and 
reports will remain on file for a minimum of two (2) years (US sites) or 25 years 
(Canada sites) after either the completion/termination of this study or the date RBX2660 
receives market approval for the indication being studied, whichever is later.  The study 
investigator must contact Rebiotix before destroying any records and reports pertaining 
to the study to ensure that they no longer need to be retained.  Rebiotix must be 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 74 of 85 
 
contacted if the study investigator plans to leave the site to ensure that arrangements for 
a new investigator or records transfer are made prior to investigator departure.  
The investigator will promptly report to the IRB/REB all changes in the research activity 
and all unanticipated problems involving risk to subjects or others, and that they will not 
make any changes in the research without prior written approval from the sponsor and 
IRB.  The investigator will adhere to all IRB/REB requirements imposed on this study. 
13.11. 
Investigator Records  
Records to be maintained by the investigator in the ISF include: 
• Protocol and all amendments 
• Signed Form 1572, or equivalent  
• Signed Financial Disclosure Form(s)  
• IRB approval letter including consent and HIPAA (US sites) 
• IRB Membership list or Letter of Assurance (US sites) 
• Signed Qualified Investigator Undertaking Form (Canadian sites) 
• REB approval letter including the Informed Consent Form (Canadian sites) 
• REB Attestation (Canadian sites) 
• REB membership list or Letter of Assurance (Canadian sites) 
• All correspondence relating to the study between the 
site/investigator/coordinator and the IRB/REB, sponsor, and CRO, as 
applicable. 
• CVs and professional licenses for all investigators and key study personnel, as 
applicable 
• Delegation of Authority and Site Signature Log 
• Product Accountability Log 
• Study Site Visitor Log 
• Study Site Training Log 
• Reports submitted to Rebiotix and/or the IRB/REB 
 
The following records must be maintained for each subject enrolled in the study: 
• Signed Informed Consent/local privacy authorization as applicable 
• Compete, accurate and current eCRFs  
• Adverse event reports and any supporting documentation 
• Protocol deviations 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 75 of 85 
 
• Relevant source documents, including procedure reports, lab reports, 
professional notes, etc. 
• Records pertain to subject death during the investigation including death 
records, death certificate, and autopsy report if performed. 
Rebiotix reserves the right to secure data clarification and additional medical 
documentation on subjects enrolled in this study at any time.  
13.12. 
Investigator Reports 
Study investigators are required to submit the following reports at the times specified 
below: 
• Adverse Events:  report all AEs to the sponsor via eCRF within ten (10) 
business days of site awareness. 
• Serious Adverse Events and suspected adverse reactions:  report to the 
sponsor via eCRF within 24 hours of site awareness. 
• Progress and Final reports:  the investigator will submit annual study progress 
reports and a final study report when the study is terminated at the site to 
Rebiotix and the IRB/REB, as required. 
13.13. 
Study Site Termination 
Rebiotix reserves the right to terminate a study site for any of the following reasons: 
• Failure to properly secure subject informed consent or HIPAA Authorization 
prior to study enrollment or the conduct of any study-required 
procedures/assessments 
• Failure to report adverse events as required in Sections 11.2 and 11.6 
• Protocol deviations 
• Repeated failure to appropriately and accurately complete eCRFs 
• Failure to enroll an adequate number of subjects 
• Loss of or unaccounted for product inventory 
• Administrative decision by the company 
13.14. 
Protocol Amendments 
Neither Rebiotix, its designees (subcontractors or CRO), nor the study investigators may 
modify this protocol without obtaining written approval of the FDA, Health Canada, 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 76 of 85 
 
and/or IRB/REBs as required.  No modifications may be made without prior written 
approval of Rebiotix. 
13.15. 
Protocol Deviations 
Any deviations from this protocol undertaken to protect the life or physical well-being of 
a subject in an emergency situation must be reported to Rebiotix within 48 hours of 
occurrence and to the respective IRB/REB as soon as possible, but in no event no later 
than five calendar days after the emergency occurs.  Protocol deviations of any kind 
must be avoided as much as possible and those that do occur will be tracked in the 
clinical study database. 
13.16. 
Inspection/Auditing 
The investigator will permit study-related inspection/auditing by the IRB/REB, sponsor, 
FDA and/or Health Canada to ensure compliance to applicable regulations, GCPs, and 
the study protocol. 
 
14. Publication Plan 
Rebiotix has unrestricted publication rights of the study data.  The study site and the 
investigator are not entitled to make any publication or release any information 
pertaining to this study or its results without the prior written consent of Rebiotix.  The 
decision as to whether to provide such consent shall be made once Rebiotix has had an 
opportunity to review the contents of any proposed publication or release regarding the 
investigation and, if necessary, to delay any publication or release in order to protect the 
confidential or proprietary nature of any information contained therein.  Merely the fact 
that the proposed publication or release contains statements unfavorable to Rebiotix 
shall not constitute grounds for prohibiting publication; however, all unfavorable 
statements must be based on adequate scientific evidence.  Rebiotix reserves the right to 
give the data to third parties for publication or release and to name co-authors.  Rebiotix 
retains the right to review and edit all proposed manuscripts, abstracts, publications, and 
presentations based upon this study or its results prior to submission to any organization, 
business, agency, person, publisher, society, or other entity. 
 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 77 of 85 
 
15. References 
Bakken JS. Feces transplantation for recurrent Clostridium difficile infection:  US 
experience and recommendations.  Microb Ecol Health Dis. 2015;26:27657.  
Eiseman B, Silen W, Bascom GS, Kauvar AJ. Fecal enema as an adjunct in the 
treatment of pseudomembranous enterocolitis. Surgery. 1958;44:854 – 9. 
FDA Guidance for Clinical Trial Sponsors: Establishment and Operation of Clinical 
Trial Data Monitoring Committees 
Kelly CR, Ihunnah C, Fischer M, et al. Fecal Microbiota Transplant for Treatment of 
Clostridium difficile Infection in Immunocompromised Patients. Am J Gastroenterol. 
2014: 109(7): 1065-1071. 
NIH/NCI Common Terminology Criteria for Adverse Events found at online at the 
following address: 
https://ctep.cancer.gov/protocolDevelopment/electronic_applications/docs/CTCAE_v5_
Quick_Reference_8.5x11.pdf 
  
 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 78 of 85 
 
16. Comorbidity Index Variables 
 
Myocardial Infarction:  Yes  No 
 
Congestive Heart Failure:  Yes  No 
 
Peripheral Vascular Disease:  Yes  No 
 
Cerebrovascular Disease:  Yes  No 
 
COPD:  Yes  No 
 
Asthma:  Yes  No 
 
Connective Tissue Disease:  Yes  No 
 
Diabetes Mellitus:  Yes  No  
Type:  Type I  Type II 
 
End-organ damage:  Yes  No 
 
Chronic Kidney Disease (Moderate to severe):  Yes  No 
 
Liver Disease:  Yes  No 
Severity:  Mild  Moderate  Severe 
 
Hypertension:  Yes  No 
 
Hemiplegia:  Yes  No 
 
Chronic Pain:  Yes  No 
 
Dementia:  Yes  No 
 
Migraines:  Yes  No 
 
Depression:  Yes  No 
 
Anxiety:  Yes  No 
 
Anemia:  Yes  No 
 
Leukemia:  Yes  No 
 
Malignant Lymphoma:  Yes  No 
 
Solid Tumor:  Yes  No  
Metastatic:  Yes  No 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 79 of 85 
 
 
Eczema:  Yes  No 
 
Acne:  Yes  No 
 
Psoriasis:  Yes  No 
 
AIDS/HIV:  Yes  No 
 
Parkinson’s Disease:  Yes  No 
 
Rheumatoid Arthritis:  Yes  No 
 
Systemic Lupus Erythematosus:  Yes  No 
 
Sjogren’s Syndrome:  Yes  No 
 
CREST Syndrome:  Yes  No 
 
Scleroderma:  Yes  No 
 
Chronic Urinary Tract Infections:  Yes  No 
 
Irritable Bowel Syndrome:  Yes  No 
 
Crohn’s Disease:  Yes  No 
 
Ulcerative Colitis:  Yes  No 
 
Peptic Ulcer Disease:  Yes  No 
 
History of Constipation:  Yes  No 
 
Gastroparesis:  Yes  No 
 
Gastroesophageal Reflux Disease (GERD):  Yes  No 
 
Alopecia (hair loss):  Yes  No 
 
  
 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 80 of 85 
 
17. Cdiff 32 Health-Related Quality of Life Questionnaire 
To be completed by the subject 
DAILY ACTIVITIES 
Over the last 7 days, because of your C. diff infection, 
1. Have you had any difficulties and/or disruption carrying out your daily activities?    
□1 
□2 
□3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
2. Have you had any difficulties carrying out your leisure activities like gardening, walking, 
etc? 
□1 
□2 
□3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
3. Has it taken you longer to perform certain tasks at work (including work in the home)? 
□1 
□2 
  □3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
4. Has your C. diff infection prevented you from leaving your house? 
□1 
□2 
□3 
□4 
□5 
Never 
Rarely 
Sometimes 
Often 
Always 
 
ANXIETY 
5. Are you afraid that your C. diff infection could come back again? 
□1 
□2 
□3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
6. Are you afraid that your C. diff infection could get worse in the future? 
□1 
□2 
□3 
□4 
□5 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 81 of 85 
 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
7. Are you afraid that the next time you'll need antibiotics, your C. diff infection will appear 
again? 
□1 
□2 
□3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
Over the last 7 days, 
8. Have you been worried about not knowing when the next diarrhea would arise? 
□1 
□2 
□3 
□4 
□5 
Never 
Rarely 
Sometimes 
Often 
Always 
 
DIET 
9. Are you afraid that certain food will worsen your C. diff infection? 
□1 
□2 
□3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
Over the last 7 days, because of your C. diff infection, 
10. Have you felt frustrated about what you can eat and when? 
□1 
□2 
□3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
SLEEP 
Over the last 7 days,  
11. Because of your C. diff infection, have you had trouble sleeping? 
□1 
□2 
□3 
□4 
□5 
Never 
Rarely 
Sometimes 
Often 
Always 
 
12. Because of your C. diff infection have you been woken up from sleep? 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 82 of 85 
 
□1 
□2 
□3 
□4 
□5 
Never 
Rarely 
Sometimes 
Often 
Always 
 
DISCOMFORT 
Over the last 7 days, 
13. Have you been bothered by abdominal pain? 
□1 
□2 
□3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
14. Have you been bothered by flatulence (wind)? 
□1 
□2 
□3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
15. Have you been bothered by a bloated stomach? 
□1 
□2 
□3 
□4 
□5 
Not at all 
A little bit 
Moderately 
Quite a bit 
Extremely 
 
16. Have you avoided wearing some clothes (tight clothes, dress, light-colored clothes ...)? 
□1 
□2 
□3 
□4 
□5 
Never 
Rarely 
Sometimes 
Often 
Always 
 
17. Have you been bothered by the smell caused by your C. diff infection related diarrhea? 
□1 
□2 
□3 
□4 
□5 
Never 
Rarely 
Sometimes 
Often 
Always 
 
18. Have you been bothered by how much time you spend on the toilet? 
□1 
□2 
□3 
□4 
□5 
Never 
Rarely 
Sometimes 
Often 
Always 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 83 of 85 
 
COPING WITH DISEASE/ HEALTH PERCEPTION 
Note! The following sentences are statements. Please indicate whether you agree or 
disagree with these statements. 
19. Despite my C diff infection I can live a normal life. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
CONTROL OF DISEASE 
20. I feel that I am not in control of my C. diff infection. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
21. I have no idea what I should do when I have my C. Diff infection? 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
IMPACT OF STRESS 
22. I believe that any stress can worsen my C. diff infection. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
DYSPHORIA 
23. I feel irritable because of my C. diff infection. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
24. I feel isolated from others because of my C. diff infection. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 84 of 85 
 
25. I feel depressed because of my C. diff infection 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
26. I feel my life is less enjoyable because of my C. diff infection. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
27. I worry about transmitting my C. diff infection to my family and/or friends. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
28. I feel much stressed because of my C. diff infection. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
RELATIONSHIPS 
29. Because of my C. diff infection, I have difficulty being around people I do not know. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
30. My C. diff infection is affecting my closest relationships. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 
SOCIAL REACTION 
31. I feel like I irritate others because of my C. diff infection. 
□1 
□2 
□3 
□4 
□5 
Totally disagree 
Mostly disagree 
Don't know 
Mostly agree 
Totally agree 
 


Rebiotix Inc.   
 
 
 
 
 
 
RBX2660 Microbiota Suspension 
 
 
 
  Open-Label Study Protocol 2019-01 
 
Version: 7.0; 26MAY2022 
   
 CONFIDENTIAL    
 
 
  Page 85 of 85 
 
32. How would you rate your overall quality of life during the past week (that is, how 
have things been going for you)? 
□1 
□2 
□3 
□4 
□5 
Very bad: could 
hardly be worse 
Pretty bad 
Good and bad 
part about 
equals 
Pretty good 
Very well: 
could hardly be 
better 
 

SAP_001.pdf: 
Rebiotix Inc. 
Statistical Analysis Plan  
Protocol 2019-01 
27 Jun 2023 
Rebiotix Inc. 
1 of 30 
Version 5.0 
CONFIDENTIAL 
Statistical Analysis Plan 
Version: 5.0 
Date: 27Jun2023 
Protocol 2019-01 
A Phase 3 Open-Label Clinical Study to Evaluate the Safety and Tolerability of Rebiotix 
RBX2660 (microbiota suspension) in Subjects with Recurrent Clostridium difficile Infection
NCT03931941 
Prepared by: 
Rebiotix Inc., A Ferring Company 
2660 Patton Road, Roseville, MN 55113 
This document is the confidential information of Rebiotix Inc.  It may not be disclosed to parties 
not associated with the clinical investigation or used for any purpose without the prior written 
consent of Rebiotix Inc. 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
2 of 30 
Version 5.0 
CONFIDENTIAL 
Revision History 
Version 
Date 
Reason 
1.0 
15Jan2019 
Initial Release 
2.0 
12Apr2019 
Added 4-week assessment for second enema follow-up, 
clarified visit windows, analyses and analysis 
populations. 
3.0 
06Sep2019 
Removed reference to a minimum number of days for 
antibiotic use, aligning requirement to the revised 
protocol v4.0. 
4.0 
24Mar2022 
• Increased enrollment allotment to allow up to 600 
treated subjects  
Note: the enrollment allotment was previously updated 
(15Oct20) to include up to 500 treated subjects. SAP 
was not revised at that time 
• 6.2.1: Table 3 added to include Analysis Windows 
for AE reporting 
• 7.6.2.5: specified 14 daily questions. 
• 8.8: Subgroup analysis test updated to include ITT 
and an appropriate 2-dimensional test (Chi-Square 
test).    
5.0 
27Jun2023 
• General clarifying changes throughout the 
document 
• Increased enrollment allotment to allow up to 750 
treated subjects 
• 6.2.1 Table 3 added additional AE analysis 
windows 
• Added 7.6.2.6 Subgroup Safety Analysis 
• Added 7.10 Subgroup Efficacy Analysis 
• 8.8 updated subgroup analysis to include 
immunocompromising conditions and inflammatory 
bowel disease (IBD) 
 
 
 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
3 of 30 
Version 5.0 
CONFIDENTIAL 
Table of Contents 
1 
LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS...................................................................... 5 
2 
STUDY OBJECTIVES AND ENDPOINTS .......................................................................................................... 6 
2.1 
PRIMARY OBJECTIVE ............................................................................................................................................ 6 
2.2 
SECONDARY OBJECTIVE ....................................................................................................................................... 6 
2.3 
OTHER OBJECTIVES .............................................................................................................................................. 6 
3 
STUDY DESIGN ........................................................................................................................................................ 7 
3.1 
GENERAL STUDY DESIGN..................................................................................................................................... 7 
3.1.1 
Treatment Success........................................................................................................................................ 8 
3.1.2 
Sustained Clinical Response ....................................................................................................................... 8 
3.1.3 
Treatment Failure ........................................................................................................................................ 8 
3.1.4 
Definition of Indeterminate Treatment Outcome....................................................................................... 9 
3.1.5 
Determination of Treatment Outcome........................................................................................................ 9 
3.2 
BLINDING .............................................................................................................................................................. 9 
3.3 
DETERMINATION OF SAMPLE SIZE ....................................................................................................................... 9 
3.4 
TREATMENT .......................................................................................................................................................... 9 
4 
CHANGES IN THE CONDUCT OF THE STUDY OR PLANNED ANALYSES.......................................... 9 
4.1 
CHANGES IN THE CONDUCT OF THE STUDY......................................................................................................... 9 
5 
BASELINE, SAFETY AND EFFICACY EVALUATIONS ............................................................................. 10 
5.1 
SCHEDULE OF EVENTS ........................................................................................................................................ 10 
5.2 
TIME POINT ALGORITHMS .................................................................................................................................. 11 
5.2.1 
Relative Day ............................................................................................................................................... 11 
5.3 
ANALYSIS POPULATIONS .................................................................................................................................... 12 
5.3.1 
Safety Population ....................................................................................................................................... 12 
5.3.2 
Intent-to-Treat Population ........................................................................................................................ 12 
5.3.3 
Modified Intent-to-Treat Population ........................................................................................................ 12 
5.3.4 
Per-Protocol Population ........................................................................................................................... 13 
5.4 
SAFETY VARIABLES............................................................................................................................................ 13 
5.4.1 
Primary Safety Endpoint ........................................................................................................................... 13 
5.4.2 
Other Safety Endpoints.............................................................................................................................. 13 
5.4.3 
Adverse Events ........................................................................................................................................... 14 
5.4.4 
Other Observations Related to Safety ...................................................................................................... 15 
5.5 
EFFICACY VARIABLES ........................................................................................................................................ 16 
5.5.1 
Efficacy Endpoint....................................................................................................................................... 16 
5.6 
OTHER ENDPOINTS ............................................................................................................................................. 16 
6 
STATISTICAL ANALYSIS ................................................................................................................................... 17 
6.1 
DISPOSITION OF SUBJECTS.................................................................................................................................. 17 
6.2 
PROTOCOL DEVIATIONS ..................................................................................................................................... 17 
6.3 
BASELINE ASSESSMENTS.................................................................................................................................... 17 
6.4 
DEMOGRAPHIC AND OTHER BASELINE CHARACTERISTICS .............................................................................. 18 
6.5 
PRIOR AND CONCOMITANT THERAPY ................................................................................................................ 18 
6.6 
SAFETY ANALYSIS .............................................................................................................................................. 18 
6.6.1 
Analyses Supporting the Primary Safety Endpoint.................................................................................. 18 
6.6.2 
Other Safety Analyses ................................................................................................................................ 18 
6.7 
EFFICACY ANALYSIS .......................................................................................................................................... 22 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
4 of 30 
Version 5.0 
CONFIDENTIAL 
6.7.1 
Analyses Supporting the Efficacy Endpoints............................................................................................ 22 
6.8 
OTHER ENDPOINTS ANALYSES........................................................................................................................... 23 
6.8.1 
Comparison of Baseline characteristics in subjects with treatment success with one dose of RBX2660 
vs. those who were unsuccessful................................................................................................................................ 24 
6.8.2 
Subject fecal microbial composition at Screening, 1-week, 4-weeks, 8-weeks, 4 months, and 6 months 
after study treatment................................................................................................................................................... 24 
6.8.3 
Cdiff32 scores at Screening, 1-week, 8-weeks, 4 months, and 6 months. .............................................. 24 
6.8.4 
Recurrence of CDI within 8 weeks of second RBX2660 treatment in subjects...................................... 24 
6.8.5 
Concentration of vancomycin-resistant enterococci in stool samples for subjects who were carriers at 
Baseline. 24 
6.8.6 
Presence of C. difficile in stool samples at Screening, 1-week, 4-weeks, 8-weeks, 4 months, and 6 
months after study treatment. .................................................................................................................................... 24 
6.9 
EXTENT OF EXPOSURE TO STUDY TREATMENT................................................................................................. 25 
6.10 SUBGROUP EFFICACY ANALYSIS ....................................................................................................................... 25 
7 
STATISTICAL METHODS ................................................................................................................................... 25 
7.1 
GENERAL METHODOLOGY ................................................................................................................................. 25 
7.2 
ADJUSTMENTS FOR COVARIATES ....................................................................................................................... 25 
7.3 
HANDLING OF DROPOUTS OR MISSING DATA ................................................................................................... 26 
7.4 
SAFETY OVERSIGHT............................................................................................................................................ 26 
7.5 
FINAL ANALYSES AND DATA MONITORING ...................................................................................................... 26 
7.5.1 
Study Stopping Rules ................................................................................................................................. 26 
7.6 
MULTI-CENTER STUDIES AND POOLING OF CENTERS ....................................................................................... 26 
7.7 
MULTIPLE COMPARISONS/MULTIPLICITY ......................................................................................................... 27 
7.8 
EXAMINATION OF SUBGROUPS........................................................................................................................... 27 
8 
COMPUTER SOFTWARE .................................................................................................................................... 30 
 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
5 of 30 
Version 5.0 
CONFIDENTIAL 
1 
LIST OF ABBREVIATIONS AND DEFINITIONS OF TERMS 
Abbreviation 
Definition 
 
 
AE 
adverse event 
ATC 
anatomical therapeutic chemical 
CDC 
Centers for Disease Control 
CI 
confidence interval 
CDI 
Clostridium difficile infection 
Cdiff32 
CDI-specific health-related quality of life survey instrument 
CSR 
Clinical Study Report 
DSMB 
Data Safety Monitoring Board 
eCRF 
electronic case report form 
FDA 
Food and Drug Administration 
HIV 
human immunodeficiency virus 
HLGT 
High level group term 
HLT 
High level term 
IBD 
inflammatory bowel disease 
ITT 
intent-to-treat 
IP 
investigational product  
ICU 
intensive care unit 
IQR 
Interquartile range 
IVIG 
intravenous immunoglobulin 
LLT 
Lower-level term 
LOCF 
Last observation carried forward 
MedDRA 
Medical Dictionary for Regulatory Activities 
mITT 
modified intent-to-treat 
mL 
milliliters 
N 
number of subjects 
PP 
per-protocol 
PT 
preferred term 
RBX2660 
investigational drug product being evaluated 
SAE 
serious adverse event 
SAP 
Statistical Analysis Plan 
SD 
standard deviation 
SMQ 
Standardized MedDRA query 
SOC 
system organ class 
TEAE 
treatment-emergent adverse event 
US 
United States 
WHO 
World Health Organization 
 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
6 of 30 
Version 5.0 
CONFIDENTIAL 
INTRODUCTION 
RBX2660 (microbiota suspension) is being studied for the prevention of recurrent Clostridium 
difficile infection (CDI) in adult subjects. The purpose of this study is to evaluate the safety and 
tolerability of RBX2660 in subjects with recurrent CDI who have had prior recurrent CDI that 
was resolved with antibiotic treatment. 
2 
STUDY OBJECTIVES AND ENDPOINTS 
2.1 
Primary Objective 
To evaluate the safety and tolerability of RBX2660 in subjects with recurrent CDI. 
2.2 
Secondary Objective 
1. To evaluate the efficacy of RBX2660 in preventing recurrent episodes of CDI 
through 8 weeks after treatment. 
2. To evaluate the sustained clinical response rate of RBX2660 after treatment. 
2.3 
Other Objectives 
1. To evaluate health-related quality of life in subjects with CDI as measured by the 
CDI-specific health-related quality of life survey instrument (Cdiff32 
questionnaire). 
2. To identify Baseline characteristics predictive of efficacy outcomes. 
3. To characterize the changes from the Baseline fecal microbial composition at 
each timepoint. 
4. To evaluate the efficacy of a second dose of RBX2660 in preventing CDI 
recurrence. 
5. To assess the clearance of vancomycin resistant enterococcus in subjects who are 
carriers at Baseline. 
6. To assess the clearance of C. difficile following enema treatment at 1-week, 4-
weeks, 8-weeks, 4-months, and 6-months after study treatment in subjects 
receiving RBX2660. 
 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
7 of 30 
Version 5.0 
CONFIDENTIAL 
3 
STUDY DESIGN 
3.1 
General Study Design 
This is an open-label, Phase 3 study to evaluate the safety and tolerability of RBX2660 in 
subjects with recurrent CDI.  
Up to 750subjects may be treated in this study. Consented subjects who meet all eligibility 
criteria are intended to be treated.  Consented subjects who do not meet the eligibility criteria 
will be considered screen failures and will not count towards the total number of subjects treated. 
Potential subjects are expected to already be taking or have just been prescribed antibiotics to 
control recurrent CDI symptoms at the time of enrollment (Screening visit) per the investigator’s 
standard of care.  Patients who have already completed their prescribed course of antibiotics to 
treat recurrent CDI are not eligible for enrollment (Screening visit) unless they have another 
recurrence that is treated with antibiotics. 
Once the Screening visit is complete, in order to proceed to the Baseline Enema Administration: 
1. Subject must meet all the inclusion and none of the exclusion criteria 
2. Antibiotics will have been administered prior to the washout period 
3. CDI symptoms must be under control leading into the antibiotic washout period  
 
Control of CDI symptoms is defined as no longer meeting the symptomatic criteria for CDI 
diarrhea which is the passage of three or more unformed/loose (i.e., Bristol Stool Scale type 6-7) 
stools in 24 or fewer consecutive hours while taking antibiotics for the two consecutive days 
prior to the washout period.  Thus, at a minimum the Subject Diary (which is started at the 
Screening visit) must show that symptoms are under control the two days prior to the washout 
period in order for the subject to receive the enema administration.     
Study treatment (enema administration) is to be completed as soon as possible, but no later than 
21 days after the Screening visit. A minimum of 24hr to a maximum of 72hr antibiotic washout 
period is required prior to administration of the study treatment. 
In-office study follow-up visits occur at weeks 1 and 8 after completing the Baseline visit.  
Telephone assessments occur at week 4 and at months 4 and 6 after the Baseline visit.  Subjects 
are required to keep a detailed diary to assess for solicited events from the date of Screening visit 
to the 1-week follow-up visit.  The diary will be collected and reviewed at the Baseline visit prior 
to enema administration. The subject will continue to complete the diary for one week following 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
8 of 30 
Version 5.0 
CONFIDENTIAL 
the Baseline visit (enema administration) and it will be collected and reviewed at the 1-week 
follow-up visit. 
Subjects may receive a second RBX2660 enema if they are deemed failures following treatment 
per the protocol-specified treatment failure definition.  This second enema is to be administered 
within 21 calendar days of failure determination.  If a subject receives a second RBX2660 
enema, the follow-up is completed via telephone assessments at 1-week, 4-week, 8-weeks, and 
6-months after completing the second enema.  A final analysis and report will be completed once 
the last subject has completed the 6-month follow-up visit for their study treatment, including 6-
month follow-up after a second RBX2660 study treatment, if applicable.   
3.1.1 Treatment Success 
Treatment success is defined as: 
• The absence of CDI diarrhea through 8 weeks after completing a study treatment.  
3.1.2 Sustained Clinical Response 
Sustained clinical response is defined as:  
• Treatment success of the presenting CDI recurrence and no new CDI episodes through 6 
months after completing a study treatment. 
3.1.3 Treatment Failure 
Treatment failure (CDI recurrence) is defined as:  
• The presence of CDI diarrhea within 8 weeks of administration of a study enema, which 
includes a positive stool test for C. difficile as determined by the central laboratory.  
To ensure consistency across clinical sites for the determination of study failure, the central 
laboratory will perform the required C. DIFF QUIK CHEK COMPLETE® Test (QCC Test) rapid 
enzyme immunoassay test for glutamate dehydrogenase (GDH) and toxins A and B.  
In the case of suspected treatment failure where there is an immediate concern for subject safety, 
including the potential for serious adverse events, a test may be conducted at the site or other 
laboratory known to the site in addition to sending a sample to the central laboratory for testing.  
In the event, the test results from the central laboratory differ from that of a local laboratory, the 
results from the central laboratory will be used in determination of treatment failure and 
eligibility to receive a second treatment with RBX2660.   


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
9 of 30 
Version 5.0 
CONFIDENTIAL 
3.1.4 Definition of Indeterminate Treatment Outcome 
If neither the protocol-specified definition for Treatment Success nor Treatment Failure is met, 
the treatment outcome will be considered Indeterminate.  
3.1.5 Determination of Treatment Outcome 
The site investigator will make the initial determination of treatment success or failure based on 
the protocol-defined study definitions.  The site investigator’s assessment will then be provided 
to the Endpoint Adjudication Committee for independent adjudication of treatment success or 
failure that will be utilized for study analysis and reporting purposes.  This may be done in an 
ongoing basis or a single meeting.  Details of the EAC logistics, activity and responsibilities will 
be included in an EAC charter.   
3.2 
Blinding 
This study is not blinded. 
3.3 
Determination of Sample Size 
The purpose of this study is to assess the safety and tolerability of RBX2660 in a recurrent CDI 
population that is broader and more inclusive than that included in prior studies using RBX2660.  
In order to continue to collect prospective safety information and allow open-label treatment 
access to a broader population of patients, up to 750 subjects will be treated with RBX2660. As 
an open-label study, there are no statistical powering considerations for the revised sample size. 
Subjects who have signed informed consent forms but do not meet all eligibility criteria will be 
considered screen failures.  Subjects who withdraw for any reason prior to administration of the 
enema will be replaced without counting toward the sample size treatment cap of 750 subjects. 
3.4 
Treatment  
Active treatment consists of one dose of RBX2660 delivered via enema. 
 
4 
CHANGES IN THE CONDUCT OF THE STUDY OR PLANNED ANALYSES 
4.1 
Changes in the Conduct of the Study 
There have been no changes to the conduct of the study or planned analysis, however, ad hoc 
analyses may be performed as needed to support regulatory review. 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
10 of 30 
Version 5.0 
CONFIDENTIAL 
5 
BASELINE, SAFETY AND EFFICACY EVALUATIONS 
5.1 
Schedule of Events 
Activity 
Screening 
(Enrollment) 
Baseline / 
Enema 
Administration 
(≤ 21 days from 
Screening) 
Follow-up 
Visits: 1- and 
8-Week (± 3 
days) 
Assessments1 
Follow-up 
Phone 
Assessment: 
Week 4 (± 3 
days) 
Follow-up 
Phone 
Assessment: 4 
and 6 months 
(± 14 days) 
Unscheduled 
Possible 
Recurrence 
Visit 
Second Enema 
Administration1 
(≤ 21 calendar 
days post Tx 
Failure) 
Second Enema Follow-
up Phone Assessment: 
1-, 4-, and 8-week (± 3 
days), and 6 months 
(± 14 days) 
Informed consent obtained 
X 
 
 
 
 
 
 
 
Demographics, medical history 
X 
 
 
 
 
 
 
 
Prescribe/continue antibiotics for CDI 
symptom control 
X 
 
 
 
 
 
 
 
Physical exam  
X 
 
 
 
 
 
 
 
Stool sent to Rebiotix by subjects for 
testing and archiving (optional) 
X 
 
X 
X 
X 
X 
 
X 
Central Lab CBC w/differential testing3 
X3 
X 
 
 
 
 
 
 
Central Lab CD4 testing 
X3 
 
 
 
 
 
 
 
Central Lab CMP & CRP testing 
X 
 
 
 
 
 
 
 
C. difficile testing4 
X4 
 
 
 
 
X4 
 
 
Central Lab stool and blood testing 
 
X 
 
 
 
 
 
 
Urine pregnancy testing performed at site 
(if applicable) 
X 
X 
 
 
 
 
X 
 
Cdiff32 Questionnaire 
X 
 
X 
 
X 
X 
 
 
Inclusion/exclusion criteria confirmed 
X 
X 
 
 
 
 
 
 
24-72hr washout period confirmed 
 
X 
 
 
 
 
X7 
 
Enema administered 
 
X 
 
 
 
 
X 
 
Product complaint (if applicable) 
 
X 
 
 
 
 
X 
 
CDI symptoms assessed 
 
X 
X 
X 
X 
X 
X 
X 
Vital signs assessed 
X 
X 
 
 
 
X 
X 
 
Weight 
X 
 
X 
X 
X 
 
 
X 
Subject Diary discussed/reviewed 
X 
X 
X5 
 
 
 
 
 
Employment status assessed 
X 
 
X6 
 
X 
 
 
 
Concomitant medications 
X 
X 
X 
X 
X 
X 
X 
X 
Adverse events assessed 
 
X 
X 
X 
X 
X 
X 
X 
Solicited events assessed2 
 
X 
X2 
 
 
 
 
 
1 Documented treatment failures may receive a second RBX2660 enema.  
2 Solicited events are collected in the Subject Diary from the day of the baseline enema until the day prior to the 1-week Follow-up visit. The Subject Diary is reviewed at the 1-week 
Follow-up visit.  Solicited events that increase in severity from Screening should be assessed for a possible adverse event. 
3 Exclusion criteria for absolute neutrophil count and CD4 should be assessed based on the blood samples collected at the Screening visit. 
4 Tested at the central laboratory 
5 Subject Diary is reviewed only at the 1-week Follow-up visit. 
6 Collected at the 8-week follow-up visit only. 
7 If antibiotics were administered to manage CDI recurrence.


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
11 of 30 
Version 5.0 
CONFIDENTIAL 
5.2 
Time Point Algorithms 
5.2.1 Relative Day 
The date of study enema administration will be considered relative day 1, and the day before 
study enema administration will be relative day -1.  Relative days will be calculated as follows 
only when the full assessment date is known (i.e., partial dates will have missing relative days, 
unless imputation methods have been specified): 
 
For days before first enema: 
Date of Assessment – Date of first enema administration 
 
For days on or after first enema: 
Date of Assessment – Date of first enema administration +1 
 
For the purpose of statistical analysis, the analysis visit windows will be calculated in terms of 
study days since the day of the study enema administration, as illustrated in the following tables: 
 
Table 1. Analysis Windows for Clinical Visits 
Visit 
Scheduled Study 
Day 
Visit Window in 
Protocol (Days) 
Visit Window for 
Analysis (Days) 
Screening Visit 
-20 through -1 
-20 through -1 
-20 through -1 
Baseline/1st Enema 
1 
1 
1 
1-week Office 
8 
5 - 11 
5 - 11 
8-weeks Office 
57 
54 - 60 
54 - 60 
 
 
 
Table 2. Analysis Windows for Phone Assessments  
Visit 
Scheduled Study 
Day 
Visit Window in 
Protocol (Days) 
Visit Window for 
Analysis (Days) 
4-weeks - Phone 
29 
26 - 32 
26 - 32 
4 months - Phone 
121 
106 – 134 
106 – 134 
6 months - Phone  
181 
166 – 194 
166 – 194 
 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
12 of 30 
Version 5.0 
CONFIDENTIAL 
Table 3. Analysis Windows for Adverse Event Reporting by Onset Interval 
Onset Interval Name 
Onset Interval 
Analysis Window 
Window for Analysis 
(Days) 
Baseline  
Screening - < Baseline 
≤ -1 
1-week  
Baseline - 1-week  
1 through 8 
4-week  
> 1-week - 4-week 
9 through 29 
8-week  
> 4-week - 8-week  
30 through 57 
0-8-week 
Baseline - 8-week 
1 through 57 
4-month 
> 8-week - 4-month 
58 through 121 
6-month 
> 4-month - 6-month 
122 through 180+ 
8-week-6-month 
> 8-week - 6-month 
58 through 180+ 
 
If a subject has more than one assessment occurring in the same visit window, the data from the 
visit closest to the scheduled study day will be used for analysis.  If two visits have the same 
distance from the scheduled study day, i.e., one visit occurs -1 day from study day, and the other 
visit occurs +1 day from study day, the data from the visit after the scheduled study day will be 
used for analysis. 
5.3 
Analysis Populations 
5.3.1 Safety Population 
The safety population (SP) is defined as the population of subjects who had any treatment 
attempted or completed.  The safety population will be used in analysis of all safety endpoints 
including the primary endpoint. 
5.3.2 Intent-to-Treat Population 
The ITT population is defined as all subjects enrolled, excluding screen failures.   
5.3.3 Modified Intent-to-Treat Population 
Analysis of the efficacy endpoints will use the modified Intent-to-Treat (mITT) population as a 
primary efficacy analysis population.  The mITT population is defined as all subjects who 
successfully received treatment but excluding;  
• subjects in whom treatment was attempted but not completed and;  
• subjects who discontinue from the study prior to evaluation of 
treatment failure/success for the 8-week efficacy endpoint if the reason 
for exit is not related to CDI symptoms.  Reason for exit will be 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
13 of 30 
Version 5.0 
CONFIDENTIAL 
captured on the exit form to allow for identification of such subjects. 
Examples of reasons unrelated to CDI symptoms may include: 
 Withdrawal of consent 
 Death unrelated to CDI 
5.3.4 Per-Protocol Population 
The per-protocol (PP) population will consist of all subjects who successfully received treatment 
analyzed according to the treatment they received, excluding: 
• Subjects who have documented protocol deviations to inclusion or 
exclusion criteria. 
• Subjects who exited prior to the 8-week efficacy evaluation if the 
reason for exit was not related to CDI symptoms in the same manner 
as the mITT population.  
5.4 
Safety Variables 
Assessment of the primary safety objective and other safety objectives will be performed on all 
subjects exposed to RBX2660 (Safety Population, see Section 6.3.1), and will include descriptive 
statistics. Additional sub-analyses of safety data may be performed on sub-populations.   
5.4.1 Primary Safety Endpoint 
Number of subjects with investigational product- and/or enema-related treatment-emergent 
adverse events (TEAEs). 
5.4.2 Other Safety Endpoints 
1. Number of adverse events per subject 
2. Timing of attributable TEAEs 
3. Duration of TEAEs 
4. Relatedness of TEAEs 
5. Severity of TEAEs 
6. Causality of TEAEs to IP, enema, C. difficile or prior condition  
7. Number of each of the following CDI-related TEAEs through 8-weeks post 
treatment: death, septic shock, toxic megacolon, colonic perforation, emergency 
colectomy, and intensive care unit (ICU) admission  
8. Onset of new chronic conditions relative to treatment administration 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
14 of 30 
Version 5.0 
CONFIDENTIAL 
5.4.3 Adverse Events 
An adverse event (AE) is any untoward medical occurrence associated with the use of IP, 
whether or not the event is considered product-related.  Preexisting conditions that worsen in 
frequency, intensity or character of the condition during study participation will be recorded as 
an AE.  AEs will be recorded for each subject from the day of enrollment through the 6-month 
telephone assessment. Serious adverse events (SAEs) will be recorded for each subject from the 
day of enrollment through the duration of the study. 
5.4.3.1 Adverse Event Dictionary 
AEs and SAEs will be classified by the Medical Dictionary for Regulatory Activities (MedDRA) 
version 20.0.  The verbatim term recorded by the investigator will be mapped in MedDRA and 
system organ class (SOC), high level group term (HLGT), high level term (HLT), preferred term 
(PT), and lower level term (LLT) will be attached to the clinical database.  Tables and listings 
will present data at the SOC and PT level. 
5.4.3.2 Adverse Event Severity 
Severity of AEs will be graded as mild, moderate, severe, or potentially life-threatening.  The 
severity grade of events for which the investigator did not record severity will be categorized as 
“Unknown” for tabular summaries and data listings and will be considered the least severe for 
the purposes of sorting for data presentation.  For summaries by severity grade, if a subject has 
multiple events occurring in the same SOC or PT, then the most severe event will be selected. 
5.4.3.3 Relationship of Adverse Events to Study Treatment 
Relationship of an AE to the Investigational Product (IP), the enema procedure, C. difficile 
disease, and a preexisting condition will be classified by the investigator as definite, probable, 
possible, or unrelated.  Related events will include AEs that are classified as definitely, probably, 
or possibly related.    
5.4.3.4 Treatment-Emergent Adverse Events 
Adverse events will be considered treatment-emergent adverse events (TEAE) according to the 
following algorithm: 
• If the complete onset date of an AE is known, then: 
o If AE onset date is prior to initial treatment date, then the AE will not be 
considered treatment-emergent. 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
15 of 30 
Version 5.0 
CONFIDENTIAL 
• If AE onset date occurs after IP exposure on or after initial treatment date, then the AE 
will be considered treatment-emergent. 
o If AE onset date is partially known, then: 
o If day is unknown, and month/year occurs on or after first enema month/year, 
then AE will be considered treatment-emergent. Otherwise, AE will not be 
considered treatment-emergent. 
o If month/day is unknown, and year occurs on or after first enema year, then AE 
will be considered treatment-emergent.  Otherwise, AE will not be considered 
treatment-emergent. 
5.4.4 Other Observations Related to Safety 
5.4.4.1 Solicited Adverse Events 
The following list of anticipated adverse events are solicited from subjects via the Subject Diary 
from the date of enrollment through the 7th day after receiving the study treatment.: 
• gas (flatulence) 
• abdominal distension or bloating 
• rectal irritation or pain 
• chills/severe shivering 
• abdominal pain or cramping 
• increased diarrhea 
• constipation 
• rectal bleeding 
• nausea 
• vomiting 
• fever ≥ 37.8° C (>100.0°F) 
Frequency and severity of the solicited AEs will also be captured in the Subject Diary. 
5.4.4.2 Major Complications of CDI Events 
Frequencies of major complications of CDI including death, septic shock, toxic megacolon, 
colonic perforation, emergency colectomy, or ICU admission will be collected through the 6-
month telephone assessment after the last study enema. 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
16 of 30 
Version 5.0 
CONFIDENTIAL 
5.4.4.3 Hospitalizations for Recurrent CDI 
Details regarding hospitalizations due to CDI, including admission and discharge date/time, 
reason for admission, whether the subject was admitted to an ICU, and ICU admission and 
discharge date/time (if applicable), will be collected following both the first and second study 
enemas 
5.5 
Efficacy Variables 
5.5.1 Efficacy Endpoint 
Assessment of secondary objectives will include descriptive statistics and be performed on pre-
defined analysis populations including Intent-to-Treat (ITT), modified Intent-to-Treat (mITT) 
and Per-Protocol (PP). Additional sub-analyses of safety data may be performed on sub-
populations.   
 
1. Efficacy Endpoint:  Recurrence of CDI within 8 weeks of treatment. 
Recurrence of CDI after 8 weeks from completion of the study treatment is considered a new C. 
difficile infection.   
The efficacy parameter used to determine treatment success is defined as the absence of CDI 
diarrhea through 8 weeks after completing a study treatment.  Efficacy assessments will occur at 
each scheduled office visit: 1-, 4- and 8-weeks. 
 
2. Efficacy Endpoint:  Loss of sustained clinical response through 6 months after 
treatment 
Sustained clinical response is defined as treatment success of the presenting CDI recurrence and 
no new CDI episodes through 6 months after completing a study treatment.  Efficacy 
assessments will occur at each scheduled phone assessment: 4 and 6 months. 
5.6 
Other Endpoints 
Other endpoints include the following: 
1. Baseline characteristics: sex, age, number of prior CDI events, race, ethnicity  
2. Subject fecal microbial composition at Screening, 1-week, 4-weeks, 8-weeks, 4 
months, and 6 months after study treatment 
3. Cdiff32 questionnaire at Screening, 1-week, 8-weeks, 4 months, and 6 months 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
17 of 30 
Version 5.0 
CONFIDENTIAL 
4. Recurrence of CDI within 8 weeks of a second RBX2660 treatment  
5. Concentration of vancomycin resistant enterococcus in stool samples for subjects 
who were carriers at Baseline at 1-week, 4-weeks, 8-weeks, 4 months, and 6 
months after study treatment. 
6. Presence of C. difficile in stool samples at Screening, 1-week, 4-weeks, 8-weeks, 
4 months, and 6 months after study treatment 
6 
STATISTICAL ANALYSIS 
6.1 
Disposition of Subjects 
A summary table will present subject disposition for all subjects enrolled.  The table will show 
the number of subjects enrolled (consented), the number of enrolled subjects not treated, and the 
number of subjects treated.  The proportion of subjects who complete the study and who 
discontinue the study will be presented.  Separately, a table or listing will be created to document 
the subjects that are included in each analysis population.  
Discontinuation will be categorized by reason as a percentage of the number of subjects in each 
analysis population and overall.  Additionally, subjects who were successfully treated but 
withdrew prior to the 8-week efficacy endpoint evaluation will be identified along with the 
reason for withdrawal to document which analysis population(s) to which they contribute.  
6.2 
Protocol Deviations 
Protocol deviations will be tracked.  The information available will be summarized by deviation 
type and listed by individual site. 
6.3 
Baseline Assessments 
Baseline assessments are collected within 20 days before or on the day of study treatment 
administration.  Summaries for age by group (< 65 and > 65), sex, ethnicity, and race will be 
provided.  Baseline height, weight and employment status will also be summarized.  CDI history 
will be summarized by total number of episodes experienced prior to treatment.  Additionally, 
the following will be summarized for each episode of CDI: duration (days), treatment 
administered, hospitalization with duration (if applicable) and available C. difficile test results.   
The following Baseline assessments will be provided in summary table and listings: 
• Medical history 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
18 of 30 
Version 5.0 
CONFIDENTIAL 
• CDI history 
• Laboratory testing (hematology) 
• Vital signs (systolic/diastolic blood pressure [mmHg], pulse rate [beats/min], 
respiration rate [breaths/min], temperature [°C]) 
6.4 
Demographic and Other Baseline Characteristics 
All Baseline summaries will include the SP, ITT, mITT, and PP populations.  Descriptive 
statistics (number of subjects [N], mean, standard deviation [SD], median, interquartile range 
[IQR], minimum, and maximum for continuous variables and number of subjects [N] and the 
percentage for categorical variables) will be provided for all Baseline measures.  
6.5 
 Prior and Concomitant Therapy  
The World Health Organization (WHO) Drug Dictionary version 2017E B2 will be used to 
classify medications by preferred term and WHO Anatomical Therapeutic Chemical (ATC) at 
the highest level of ATC.  Listings of all concomitant medications will be made by WHO ATC 
classification of ingredients and by preferred term.  All listings of usage of medications will be 
based on the SP. 
6.6 
Safety Analysis 
The SP will be used to summarize all adverse event data, unless otherwise specified. Safety data 
will be summarized for events after the first and second enemas, as well as combined. Events 
occurring after the first enema will be counted up to the date of retreatment, or study exit. Events 
on, or after, the date of a second enema will be assigned to the second period. The combined 
analysis will consider all events, after first enema through study exit, even if a subject receives a 
second enema.    
6.6.1 Analyses Supporting the Primary Safety Endpoint 
Assessment of the primary safety objective will include descriptive statistics and be performed 
on the SP. Additional sub-analyses of safety data may be performed on sub-populations.   
6.6.2 Other Safety Analyses  
6.6.2.1 Adverse Events 
A summary of adverse events, TEAEs, non-serious TEAEs, and serious TEAEs will be 
summarized using counts of the number of events and frequencies (counts and percentages) of 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
19 of 30 
Version 5.0 
CONFIDENTIAL 
the number of subjects.  The incidence of each preferred term (PT) within the primary system 
organ class (SOC) as well as overall primary SOC incidence will be presented.  Summaries may 
also be presented by PT, irrespective of SOC.  A subject with multiple events coded to the same 
PT within a primary SOC will be counted only once for the PT within the primary SOC.  
Likewise, a subject with multiple events coded to the same SOC will be counted only once 
within the SOC. 
An overall summary of AEs will present the incidence of (1) all TEAEs, (2) TEAEs related to IP, 
(3) TEAEs related to enema procedure, (4) TEAEs related to C. difficile disease, (5) TEAEs 
related to a preexisting condition, (6) serious TEAEs, (7) serious TEAEs related to IP, (8) serious 
TEAEs related to the enema procedure, (9) serious TEAEs related to C. difficile disease, (10) 
serious TEAEs related to a preexisting condition, and (11) TEAEs leading to death. 
Frequency of occurrence and number and percent of subjects experiencing an event through 6 
months follow-up will be presented for both the first and second enemas as follows: 
• All TEAEs 
• TEAEs by maximum severity 
• TEAEs by relatedness to IP 
• TEAEs by relatedness to C. difficile disease 
• TEAEs by relatedness to enema procedure 
• TEAEs by relatedness to preexisting condition 
• TEAEs resulting in subject withdrawal 
• TEAEs resulting in death 
• Serious TEAEs 
• Serious TEAEs by maximum severity 
• Serious TEAEs by relatedness to IP 
• Serious TEAEs by relatedness to C. difficile disease 
• Serious TEAEs by relatedness to enema procedure 
• Serious TEAEs by relatedness to preexisting condition 
• Serious TEAEs resulting in subject withdrawal 
• Serious TEAEs resulting in death 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
20 of 30 
Version 5.0 
CONFIDENTIAL 
For the summary of AEs by maximum severity, if a subject has multiple events occurring in the 
same SOC or same PT, then the event with the highest severity will be counted.  For AEs 
reported by causality, if a subject has multiple events occurring in the same SOC or same PT, the 
event with the highest association will be summarized. 
A summary of TEAE and serious TEAE characteristics (severity, relatedness to IP, relatedness to 
C. difficile disease, relatedness to enema procedure, and relatedness to preexisting condition by 
outcome) will also be presented by first and second enema and overall. 
Incidence of AEs and serious AEs will also be presented by onset interval separately for the first 
and second enemas (as applicable), as well as a combined presentation for the following 
intervals:  
• Baseline (onset date prior to date of first enema)  
• IP administration (onset date on the date of the first and second enema, as applicable) 
• Intervals relative to the enema date (first and second enemas, as applicable):  
o 1-Week (day 8), 4-Weeks (day 29), 8-Weeks (day 57), 4 Months (Day 120), and 6 
Months (Day 180). 
For data presentation, SOC will be ordered alphabetically, with PT sorted by decreasing total 
frequency.  No inferential statistics will be provided for the AE data. 
Subject listings will be presented for all AEs including SAEs. 
6.6.2.2 Major Complications of CDI events 
Major complications of CDI events include death, septic shock, toxic megacolon, colonic 
perforation, emergency colectomy, or ICU admission collected through the 6-month telephone 
assessment after the last study enema.  Incidence of major complications of CDI events will be 
summarized by the first and second enemas. 
6.6.2.3 Hospitalizations for Recurrent CDI 
The number of subjects requiring hospitalization due to recurrent CDI through 8 weeks 
following the completion of the study treatment will be summarized, along with the length of 
hospital stay, the number of subjects requiring ICU admission, and the length of ICU stay during 
hospitalization. 
A listing of all hospitalizations due to CDI throughout the study will be generated. 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
21 of 30 
Version 5.0 
CONFIDENTIAL 
6.6.2.4 Rate of onset of new chronic conditions for those treated with RBX2660 
Documentation of physician diagnosed chronic conditions for all subjects will be completed at 
Baseline and compared to new physician diagnosed chronic conditions reported at 1-week, 4-
weeks, 8-weeks, 4 months and 6 months.  Chronic condition is defined as a condition lasting >3 
months.  This will be presented as a rate of chronic conditions onset for the combined first and 
second enemas, as well as separately for first and second enemas. 
 
6.6.2.5 Subject Diary including Solicited Adverse Events and Completion 
Compliance 
All solicited adverse events recorded in the Subject Diary will be summarized utilizing 
frequencies (number of events), proportions (number of subjects with the event) and 95% CIs for 
categorical variables and using the descriptive statistics as listed in Section 8.1 for continuous 
variables.  
For each solicited event, severity scores will be summarized as both categorical and continuous 
values.  For continuous summaries, severity scores will be identified as either pre-treatment or 
post-treatment (all diary entries captured after the first enema), and the average for each period 
will be calculated across individual subjects.  Baseline for continuous summaries will be 
considered the average during the pre-treatment period.  For categorical summaries, if a subject 
reports more than one severity score on the same date, the maximum severity will be used. 
Baseline for categorical summaries will be considered the last non-missing assessment prior to 
the enema. 
For each categorical summary of event frequency, a two-sided 95% CI will be calculated using 
the normal approximation of the binomial. 
The following summaries will be produced for the first enema: 
• Frequency of severity scores on day of enema administration  
• Frequency of severity scores on day 1 through 1-week post-treatment  
• Frequency of maximum post-treatment severity score  
Compliance in returning completed Subject Diaries will be calculated by dividing the number of 
diaries turned in, whether complete or not, by the number of diaries expected to be turned in.  
Furthermore, compliance will be summarized by calculating the proportion of subjects who 
turned in “complete” diaries, where complete is defined as answering all 14 daily questions (e.g. 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
22 of 30 
Version 5.0 
CONFIDENTIAL 
11 solicited AE, Bristol Stool Type, New illnesses/injuries, New medications) for at least 80% of 
the expected number of diaries.   
6.6.2.6 Subgroup safety analysis 
The overview of AEs and TEAEs by SOC and PT will be summarized by the following 
subgroups: 
• Subjects with immunocompromising conditions; 
• Subject without immunocompromising conditions; 
• Subjects with inflammatory bowel disease at time of IP administration;  
• Subject without inflammatory bowel disease at time of IP administration.  
Note: Inflammatory bowel disease includes the medical history with PT term “Ulcerative 
colitis”, “Crohn's disease”, or “Inflammatory bowel disease”. 
 
6.7 
Efficacy Analysis  
6.7.1 Analyses Supporting the Efficacy Endpoints 
6.7.1.1 Treatment Success 
Assessment of secondary efficacy objectives will include descriptive statistics and will be 
performed on the mITT population. Additional sub-analyses of safety data may be performed on 
sub-populations.   
6.7.1.1.1 Recurrence of CDI within 8 weeks of treatment 
 
Recurrence of CDI is defined as the presence of CDI diarrhea within 8 weeks (54-60 days) of 
administration of a study enema, which includes a positive stool test for C. difficile as determined by 
the central laboratory. A CDI with an onset after 8 weeks (> 60 days) from completion of the 
study treatment is considered a new CDI. Onset of CDI is the date that the symptoms first 
started. 
 
The efficacy parameter used to determine treatment success is defined as the absence of CDI 
diarrhea through 8 weeks after completing a study treatment.  Efficacy assessments will occur at 
each scheduled contact: 1-week, 4-weeks, 8-weeks. 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
23 of 30 
Version 5.0 
CONFIDENTIAL 
6.7.1.1.2 Sustained clinical response  
The endpoint of interest is sustained clinical response (i.e., the rate of treatment success of the 
presenting CDI recurrence and no new CDI episodes for greater than 8 weeks after completing a 
study treatment).  Efficacy assessments will occur at the 4- and 6-month phone assessments. 
6.7.1.2 Sensitivity Analysis for the Efficacy Endpoints 
The efficacy analyses will be repeated using the ITT and PP population to assess the sensitivity 
of the endpoints.  The ITT analysis will serve as the conservative analysis as it considers all 
subjects who exit prior to the 8-week efficacy assessment as treatment failures regardless of 
treatment failure documentation.  
Finally, the sensitivity of the efficacy endpoints will be assessed in a multivariate logistic 
regression adjusting for possible interactions of the following covariates: age (< 65 years, ≥ 65 
years), sex (Female, Male), race group (White, Non-white), ethnicity (Hispanic-Latino, not 
Hispanic-Latino), site geography (outside the US, Eastern US*, Southern US*, Northern US*, 
Western US*), and categories of number of previous episodes of CDI recurrence at Baseline (≤ 
3, > 3). Comorbidities will also be reviewed for possible interactions. This analysis will be 
performed on all populations where at least 20 subjects are available in each sub-group. 
*States included in the identified US geographical regions are as follows: 
• Eastern US: Connecticut, Delaware, District of Columbia, Maine, Maryland, 
Massachusetts, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode 
Island, Vermont, Virginia, West Virginia 
• Southern US: Alabama, Arkansas, Georgia, Florida, Kansas, Kentucky, Louisiana, 
Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas 
• Northern US: Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Nebraska, North 
Dakota, South Dakota, Wisconsin 
• Western US: Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, 
Oregon, Utah, Washington, Wyoming 
6.8 
Other Endpoints Analyses 
Additionally, the other analyses will be conducted on other populations or subgroups as needed.  


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
24 of 30 
Version 5.0 
CONFIDENTIAL 
6.8.1 Comparison of Baseline characteristics in subjects with treatment success with one 
dose of RBX2660 vs. those who were unsuccessful. 
A multivariate analysis or regression analysis will be used to identify predictors (if any) for 
subject success with one RBX2660 dose vs. those who were unsuccessful, for example, age or 
number of prior CDI events.   
6.8.2 Subject fecal microbial composition at Screening, 1-week, 4-weeks, 8-weeks, 4 
months, and 6 months after study treatment. 
Descriptive statistics will be used to present the changes from Screening fecal microbial 
composition to those at 1-week, 4-weeks, 8-weeks, 4 months, and 6 months after study treatment 
for those subjects treated with RBX2660.   
6.8.3 Cdiff32 scores at Screening, 1-week, 8-weeks, 4 months, and 6 months. 
Changes from Screening in the Cdiff32 scores will be summarized using descriptive statistics.  
Last observation carried forward (LOCF) will be used to impute missing post-Baseline data.  No 
inferential statistics will be performed. 
6.8.4 Recurrence of CDI within 8 weeks of second RBX2660 treatment in subjects. 
Determine the treatment success rate of those subjects who received two doses of RBX2660.  
This success rate will be calculated at 8 weeks following the second RBX2660 enema.  
6.8.5 Concentration of vancomycin-resistant enterococci in stool samples for subjects who 
were carriers at Baseline. 
Lab generated values for the presence of vancomycin resistant enterococcus based on submitted 
stool samples at Baseline and at 1-week, 4-weeks, 8-weeks and 4 and 6 months will be assessed 
for all subjects to identify any trends in the clearance of vancomycin-resistant enterococci 
following enema treatment.  
6.8.6 Presence of C. difficile in stool samples at Screening, 1-week, 4-weeks, 8-weeks, 4 
months, and 6 months after study treatment. 
Lab generated values for the presence of C. difficile based on submitted stool samples at Baseline 
and at 1-week, 4-weeks, 8-weeks, 4 months, and 6 months will be assessed for all subjects to 
identify any trends in the clearance of C. difficile following enema treatment.  


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
25 of 30 
Version 5.0 
CONFIDENTIAL 
6.9 
Extent of Exposure to Study Treatment 
The number and proportion of enemas (RBX2660) administered for each subject will be 
summarized using descriptive statistics.  Time between study enema administrations will be 
summarized using descriptive statistics for both first and second enemas.   
6.10 
Subgroup Efficacy Analysis 
The Chi-Square test will be used to assess the difference between the following additional 
subgroups: 
• Subjects with immunocompromising conditions vs. Subject without 
immunocompromising conditions; 
• Subjects with inflammatory bowel disease vs. Subject without inflammatory bowel 
disease at time of IP administration.  
 
Note: Inflammatory bowel disease includes a medical history with PT term “Ulcerative colitis”, 
“Crohn's disease”, or “Inflammatory bowel disease”. 
 
7 
STATISTICAL METHODS 
7.1 
General Methodology 
Data will be summarized using descriptive statistics with SAS Version 9.3 or higher.  
Confidence intervals (CI) will be constructed at the level of 95% unless specified otherwise.  For 
continuous variables, descriptive statistics (number of subjects [N], mean, standard deviation 
[SD], median, inter-quartile range [IQR], minimum, and maximum) will be generated.  For 
discrete/categorical variables, the number and percentage of non-missing subjects will be 
generated.  Standard operating procedures (SOPs) will be followed in the creation, validation and 
quality control of all data displays and analyses. 
Subject listings of all data from the eCRFs as well as any derived variables will be presented. 
7.2 
Adjustments for Covariates 
No adjustments for covariates are planned as this is a single-arm study. 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
26 of 30 
Version 5.0 
CONFIDENTIAL 
7.3 
Handling of Dropouts or Missing Data 
No imputations will be used in analyses/summaries.  However, a LOCF analysis will be used for 
evaluation of the Cdiff32 scores.  Missing safety data will not be imputed beyond the 
adjustments for adverse event data mentioned in Section 6.4.3. 
7.4 
Safety Oversight 
The Medical Monitor provides review of serious adverse events or events reported by the site as 
related to the investigational product or enema procedure to assess accuracy of reporting as 
related to seriousness and causality, and periodic review of adverse events for trends.  Details of 
this review are documented in a Safety Management Plan.  The Medical Monitor’s review will 
be provided to the DSMB for analysis purposes and as applicable for the proper adjudication of 
potential study stopping rules (see Section 8.5.1). 
7.5 
Final Analyses and Data Monitoring 
A final analysis and report will be completed once the last subject has completed the 6-month 
follow-up visit for their study treatment, including 6-month follow-up after a second RBX2660 
study treatment, if applicable.  
7.5.1 Study Stopping Rules 
 Enrollment will be paused if any of the following events are identified and the DSMB 
determines that there is probable cause that the IP or enema procedure contributed to the event: 
1. There is probable cause that IP or enema procedure (e.g., due to transfer from an 
RBX2660 donor) contributed to a pathogenic intestinal infection in the stool of 
any subject, or 
  
2. Any series of events of major significance such as death or other serious outcome 
for which a causal connection with the IP is plausible and represents an excess of 
the important adverse event(s).  
7.6 
Multi-center Studies and Pooling of Centers 
The study will be conducted at up to 80 clinical trial sites in the US and Canada.  
This is a multicenter study and before data from all sites are pooled, the effect of site will be 
assessed for the secondary efficacy endpoints.  A sufficient number of subjects (≥ 7) will be 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
27 of 30 
Version 5.0 
CONFIDENTIAL 
required within each investigative site to determine if there are any outlying sites.  If an 
investigative site is unable to enroll a sufficient number of subjects, it may be necessary to 
combine smaller sites (where enrollment is too low to detect differences) to create “pseudo-
sites”.  Sites with < 7 subjects will be considered eligible for pooling.  Eligible sites will be 
pooled sequentially with other sites in the same region until a sufficient number of subjects are 
reached (at least seven). 
In this process, sites with < 7 subjects will be ordered numerically in ascending order, based on 
the investigative site number.  Sites with < 7 subjects will then be sequentially pooled with other 
sites in the same region in ascending order by site number until the resulting pseudo-site has at 
least 7 subjects meeting the PP population definition, thus creating a new “pseudo-site”.  The 
process will begin again with the next sequential small site until all small sites have been pooled 
with other sites in the same region into a pseudo-site.   
7.7 
Multiple Comparisons/Multiplicity 
As this study is not powered for a primary objective, and as descriptive statistics will be used for 
analysis of the primary objective, no adjustments for multiplicity are required. 
7.8 
Examination of Subgroups 
Subgroup analysis of age (< 65 years, ≥ 65 years), sex (Female, Male), race group (White, Non-
white), ethnicity (Hispanic-Latino, not Hispanic-Latino), site geography (outside the US, Eastern 
US*, Southern US*, Northern US*, Western US*) and number of previous episodes of CDI 
recurrence at Baseline will be conducted on the efficacy analysis if a sufficient sample size exists 
for each subgroup.  This analysis will include the ITT and mITT analysis populations to 
understand any differences.  
*States included in the identified US geographical regions are as follows: 
• Eastern US: Connecticut, Delaware, District of Columbia, Maine, Maryland, 
Massachusetts, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode 
Island, Vermont, Virginia, West Virginia 
• Southern US: Alabama, Arkansas, Georgia, Florida, Kansas, Kentucky, Louisiana, 
Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas 
• Northern US: Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Nebraska, North 
Dakota, South Dakota, Wisconsin 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
28 of 30 
Version 5.0 
CONFIDENTIAL 
• Western US: Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, 
Oregon, Utah, Washington, Wyoming 
 
Other subgroups will include subjects with a, medical history of Ulcerative Colitis (UC), Crohn’s 
Disease (CD), and/or Inflammatory Bowel Disease (IBD) which was ongoing at the time of 
study treatment, and medical history of immunocompromising condition(s) which was ongoing 
at time of IP administration.   
Because immunocompromising conditions may result from medications, diseases, or a 
combination of both, the following algorithm will be used to identify participants in this 
subgroup:     
 Medical History Rules 
 
Standardized MedDRA query (SMQ) of Malignant tumours 
Search will require at least 2 Broad terms or at least1 narrow term for events which were 
ongoing at the time of IP administration.  
 
Other Medical History  
Preferred Terms (PT), High level Term (HLT), or High Level Group Term (HLGT) will be used 
to identify the following conditions, which were ongoing at the time of IP administration, based 
upon the Centers for Disease Control (CDC) guidelines for immunocompromised conditions 
listed under CDC Pneumococcal Vaccine Recommendations (Pneumococcal Vaccine 
Recommendations | CDC) 
• PT: End Stage Renal Disease 
• PT: Renal Failure  
• PT: Asplenia 
• PT: HIV 
• PT: HIV infection 
• HLT: Haemoglobinopathies congenital 
• HLGT: Immunodeficiency syndromes 
Concomitant Medications: 
 
Anatomical Therapeutic Chemical (ATC) classification will be used to identify 
immunocompromising medications taken within the following window: Two weeks prior to the 
first IP administration to 8 weeks after administration. Only systemic routes of administration 
will be included such as those taken orally or by injection (intramuscular, subcutaneous, or 
intravenous); topical medications will be excluded. 
 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
29 of 30 
Version 5.0 
CONFIDENTIAL 
• ATC classification H02AB or H02BX – Corticosteroids.  These medications must have 
been taken for 5 consecutive days within the window specified above.  
o As described in the protocol, 20 mg prednisone-equivalent is considered to be an 
immunocompromising dose. Prednisone equivalent doses are listed in the table 
below where the dose of the medications below is multiplied by the applicable 
conversion factor listed in the table (e.g., 4 mgs of Dexamethasone is equivalent 
to 26.8 mg prednisone)  
o The dosing regimen will be incorporated into a calculation of total daily dose, 
with a total of 20mg prednisone-equivalent per day as the threshold for 
immunocompromising.   
Preferred Term 
Prednisone equivalent 
conversion factor 
(multiplication) 
Cortisone 
0.2 
Dexamethasone 
6.7 
Hydrocortisone 
0.25 
Methylprednisolone 
1.25 
Methylprednisolone Sodium Succinate 
1.25 
Prednisolone 
1 
Prednisone 
1 
Triamcinolone 
1.25 
 
• ATC classification L01, L03, L04 includes many systemic immunosuppressive 
medications with varying doses, dosing regimens, routes of administration, and half-lives. 
Use of any of the medications used two weeks prior to IP administration to 8 weeks after 
administration will be considered as immunocompromising.  Note: ACT classification 
L02 will be excluded since these hormone-based medications are not considered to be 
immunocompromising.  
A final output will include a summary table summarizing the total number of subjects flagged as 
immunocompromised and a listing detailing the immunocompromised subjects as seen in 
example Tables 1 and 2.  
 
Example Table 1.  Summary information Inflammatory Bowel Disease: 
 
Ulcerative 
colitis 
(UC) 
Crohns disease 
(CD) 
Inflammatory bowel 
disease (IBD) 
Total 
Number of participants 
[number] 
[number] 
[number] 
[number] 
 
 


Rebiotix Inc.          
Statistical Analysis Plan  
Protocol 2019-01 
 
27 Jun 2023 
Rebiotix Inc. 
30 of 30 
Version 5.0 
CONFIDENTIAL 
Example Table 2.  Listing of Immunocompromised Subjects  
(Note: listing should include one entry per row to display subjects with multiple SMQ hits in 
multiple rows) 
 
USUBJID 
*SMQ/[B or N]/MHDECOD 
 
CMCLAS/ 
CMDecod/ 
CMRoute/ 
CMDose/CMDoseU/CMDoseFRQ 
CMDoseEq** 
*SMQ /[B or N]= Standardized MedDRA Query Broad (B) or Narrow (N)**CMDoseEq=concomitant 
medication dose equivalent 
 
8 
COMPUTER SOFTWARE 
All analyses will be performed by Medpace using Version 9.3 or later of SAS software. All 
summary tables and data listings will be prepared utilizing SAS software.