A Phase 2a, Randomized, Double-Blind, Placebo-Controlled, Evaluation of PLN-74809 on Type 1 Collagen Deposition Using 68Ga-CBP8 PET/MRI Imaging in Participants With Idiopathic Pulmonary Fibrosis (IPF)
Phase: PHASE2
Conditions: Idiopathic Pulmonary Fibrosis
Sponsor: Pliant Therapeutics, Inc.

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 1  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
 
 
CLINICAL TRIAL PROTOCOL 
PLN-74809-IPF-205 
Study Title: 
A Phase 2a, randomized, double-blind, placebo-controlled evaluation of 
PLN-74809 on type 1 collagen deposition using 68Ga-CBP8 PET/MRI 
imaging in participants with idiopathic pulmonary fibrosis (IPF) 
Study Number: 
PLN-74809-IPF-205 
Study Phase: 
2a 
Product Name: 
PLN-74809-000 
IND Number: 
139,998 
Indication: 
Treatment of idiopathic pulmonary fibrosis (IPF) 
Sponsor: 
Pliant Therapeutics Inc.  
260 Littlefield Avenue 
South San Francisco, CA 94080, USA 
Sponsor Study 
Director: 
 
 
Pliant Therapeutics Inc. 
 
 
 
 
Date 
Original Protocol (v1.0): 
22 June 2021 
Amendment 1: 
4 October 2021 
 
 
Confidentiality Statement 
This document is the property of Pliant Therapeutics. The confidential information in this document 
may not be used, published or disclosed without the prior written consent of Pliant Therapeutics 
except to the extent required under applicable laws or regulations.  

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 2  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
SYNOPSIS 
Study Title: 
 
A Phase 2a, randomized, double-blind, placebo-controlled evaluation of PLN-74809 
on type 1 collagen deposition using 68Ga-CBP8 PET/MRI imaging in participants with 
idiopathic pulmonary fibrosis (IPF) 
Study Number: 
PLN-74809-IPF-205 
Study Phase:  
2a 
Number of 
Participants 
Approx. 12 (8 receiving PLN-74809 and 4 receiving placebo) 
Objectives: 
Primary:  
• Quantification of type 1 collagen in the lung following 12 weeks of treatment with 
PLN-74809, as assessed by changes from Baseline in 68Ga-CBP8 positron 
emission tomography (PET) / magnetic resonance imaging (MRI) tracer uptake 
patterns 
Secondary: 
• Assessment of the safety and tolerability of PLN-74809 in idiopathic pulmonary 
fibrosis (IPF) participants 
Exploratory: 
• Relationship between PLN-74809 systemic exposure and PET imaging and 
biomarkers in IPF participants 
• Forced vital capacity (FVC): absolute FVC volume and FVC as percent of 
predicted as assessed by spirometry 
• Patient-reported outcome (PRO): a visual analog scale (VAS) for cough severity 
Study Design: 
This is a Phase 2a, single-center, randomized, double-blinded, placebo-controlled 
study to evaluate type 1 collagen deposition in the lungs following once-daily (QD) 
treatment with 160 mg PLN-74809 for 12 weeks in participants with IPF. 
The study consists of an up to 28-day screening period, a 12-week treatment period, 
and a 2 week (±3 days) post treatment follow-up period.  
Potential participants who provide written informed consent will be screened for study 
eligibility up to 28 days before administration of the first dose of study drug. 
Approximately 12 eligible participants will be randomized in a 2:1 ratio (160 mg 
PLN-74809 vs placebo; 8 receiving PLN-74809 and 4 receiving placebo) on Day 1 
(Visit 3). Study treatment will be administered once daily for 12 weeks. 
Randomization will be stratified by use of standard of care (SoC) IPF therapy with 
pirfenidone or nintedanib (SoC use; yes or no). 
68Ga-CBP8 PET/MRI scans will be conducted within 7 days prior to baseline and at or 
within 7 days prior to Week 12, as indicated in the Schedule of Events. 
Participants who discontinue study drug for safety reasons prior to completion of 
12 weeks of treatment will be encouraged to remain in the study to complete all 
remaining assessments; if this is not feasible, they will be asked to return to the clinic 
for an Early Termination (ET) visit for follow-up evaluations. If a participant elects to 
withdraw from the study after the 6th week of randomization, an end of participation 
68Ga-CBP8 PET/MRI will be offered to the participant to enhance appropriate data 
capture. 
Potential acute exacerbations, respiratory-related hospitalizations, and/or respiratory-
related deaths will be reviewed by an adjudication committee. 
 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 3  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Study Population: 
Inclusion Criteria: 
1. Participants, aged 40 years or older 
2. Diagnosis of IPF, within 8 years prior to screening, according to the 
American Thoracic Society (ATS)/ European Respiratory Society (ERS)/ 
Japanese Respiratory Society (JRS)/ Latin American Respiratory Society 
(ALAT) 2018 guidelines  
Note: If IPF diagnosis is within > 3 to ≤ 8 years at screening, the participant 
must have evidence of progression within the last 24 months, as defined by 
decline in FVC percent predicted based on a relative decline of ≥ 5%   
3. FVC percent of predicted ≥ 45%; historical FVC for entry in the study is 
permitted if within 1 month of screening 
4. Diffusing capacity for carbon monoxide (DLco) (hemoglobin-adjusted) 
≥ 30%; historical DLco for entry in the study is permitted if within 1 month 
of screening 
5. Participants currently receiving treatment for IPF with nintedanib or 
pirfenidone are allowed, provided these drugs have been given at a stable 
dose for at least 3 months before the Screening Visit and are expected to 
remain unchanged during the study (stable dose is defined as the highest dose 
tolerated by the participant during ≥ 3 months) 
6. Estimated glomerular filtration rate ≥ 50 mL/min, according to the Cockcroft-
Gault equation 
7. Female participants of non-childbearing potential must be either surgically 
sterile or postmenopausal  
8. Female participants of childbearing potential must use a contraceptive 
method with a failure rate of <1% per year or remain abstinent (refrain from 
heterosexual intercourse) during the treatment period and for 1 month after 
the last dose of study treatment 
9. Male participants with female partners of childbearing potential must agree to 
use contraceptive measures or remain abstinent (refrain from heterosexual 
intercourse) during the treatment period and for at least 3 months after the last 
dose of study treatment. 
10. Participants must agree to abstain from sperm or egg donation for the 
duration of the study, through to 3 months or 1 month, respectively, after 
administration of the last dose of study drug 
11. Able to understand the purpose of the study and its procedures and to sign a 
written informed consent form (ICF) 
Exclusion Criteria: 
1. Hypersensitivity to PLN-74809 or to any of the excipients to PLN-74809 
2. Not a suitable candidate or unlikely to comply with study requirements, in the 
opinion of the Investigator 
3. Receiving any nonapproved agent intended for treatment of fibrosis in IPF  
4. Forced expiratory volume during the first seconds of the forced breath 
(FEV1)/FVC ratio < 0.7 at screening 
5. Clinical evidence of active infection, including but not limited to bronchitis, 
pneumonia or sinusitis that can affect FVC measurement during screening or 
at randomization 
6. Any other condition that prevents the correct assessment of spirometry 
performance (e.g., a broken rib or chest pain of other origin that prevents 
adequate forced breathing) 
7. Known acute IPF exacerbation or suspicion by the Investigator of such, 
within 6 months of screening 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 4  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
8. Severe pulmonary hypertension 
9. Smoking of any kind (not limited to tobacco) within 3 months prior to 
screening, as documented in the medical history, or unwilling to avoid 
smoking throughout the study 
10. Lower respiratory tract infection requiring antibiotics within 4 weeks prior to 
screening and/or during the screening period 
11. History of malignancy within the past 5 years or ongoing malignancy other 
than basal cell carcinoma, resected noninvasive cutaneous squamous cell 
carcinoma, or treated cervical carcinoma in situ 
12. End-stage liver disease 
13. Renal impairment or end-stage kidney disease requiring dialysis 
14. History of unstable or deteriorating cardiac or pulmonary disease (other than 
IPF) within the 6 months prior to screening, including but not limited to the 
following:  
a. Unstable angina pectoris or myocardial infarction  
b. Congestive heart failure requiring hospitalization  
c. Uncontrolled clinically significant arrhythmias (e.g., resulted in health 
care utilization or hospitalization) 
15. Any clinically relevant electrocardiogram (ECG) abnormalities, including but 
not limited to, QT interval corrected for heart rate using Fridericia's formula 
(QTcF) > 450 msec for males or > 460 msec for females at the Screening 
Visit (including Day -1) or prior to administration of the initial dose of study 
drug 
16. Any medical condition that, in the opinion of the Investigator, may make the 
candidate not suitable for the study 
17. History of anaphylaxis to intravenous (IV) drugs 
18. Any of the following liver function test criteria above specified limits: total 
bilirubin >1.5× the upper limit of normal (ULN); aspartate aminotransferase 
(AST) or alanine aminotransferase (ALT) >3× ULN; alkaline phosphatase 
> 2.5× ULN.  
Note: participants currently receiving nintedanib or pirfenidone as IPF SoC 
treatment, who have previously presented any liver function test elevations 
associated with nintedanib or pirfenidone treatment greater than that 
described above or resulting in dose reduction, treatment interruption, or 
discontinuation are not eligible. 
19. Any of the following at screening: hemoglobin < 10.0 g/dL, neutrophils 
< 1500 /mm3, or platelets < 100,000 /mL 
20. Electrical implants such as cardiac pacemaker or perfusion pump 
21. Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, 
artificial hearts, valves with steel parts, metal fragments, shrapnel, metallic 
tattoos anywhere on the body, tattoos near the eye, or steel implants, 
ferromagnetic objects such as jewelry or metal clips in clothing 
22. Claustrophobic reactions 
23. Research-related radiation exposure exceeds current Radiology Department 
guidelines (i.e. 50 mSv in the prior 12 months) 
24. Unable to lie comfortably on a bed inside the PET/MRI 
25. Body mass index (BMI) > 33 kg/m2 (limit of the PET/MRI table) 
26. Prior or current radiation to the thorax 
27. Pregnant or lactating female participants 
28. Male participants with pregnant female partners 
29. A medical or surgical condition known to affect drug absorption (e.g., major 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 5  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
gastric surgery)  
30. Participation in a clinical study with an investigational agent in the 30 days 
prior to screening or 5 half-lives of the investigational drug, whichever is 
longer trial, apart from PLN-74809 
31. Currently receiving and expected to remain on treatment during the study 
with: potent and concomitant inhibitors or inducers of cytochrome P450 
(CYP) 3A4, 2C9 or 2C19; potent inhibitors or inducers of P-glycoprotein 
(P-gp), breast cancer resistance protein (BCRP) or organic anion transporting 
polypeptide (OATP) 1B1/1B3 transporters; digoxin (a P-gp substrate with a 
narrow therapeutic window) 
32. Daily use of phosphodiesterase-5 (PDE-5) inhibitor drugs (e.g., sildenafil, 
tadalafil, other) (Note: Intermittent use for erectile dysfunction is allowed.) 
33. Surgical procedures planned to occur during the study period 
34. Uncontrolled systemic arterial hypertension 
35. Likely to have lung transplantation during the study (being on transplantation 
list is acceptable)  
Test Product, Dose, 
and Mode of 
Administration: 
PLN-74809 (80 mg immediate release tablets) 
160 mg, oral, QD 
Reference Therapy, 
Dose, and Mode of 
Administration: 
Matching placebo - Oral, QD 
 
 
 
PET Tracer, Dose, 
and Mode of 
Administration: 
The 68Ga-CBP8 PET/MRI tracer is not considered a study treatment but is an 
investigational tool used during the PET procedure for obtaining the images necessary 
for this trial. [68Ga]CBP8 is an intravenous injection given within 7 days prior to 
baseline and at or within 7 days prior to Week 12. The radiochemical dose is up to 
12.9 mCi but in practice, the dose has averaged 5.5 mCi per subject. 
 
Duration of 
Treatment: 
12 weeks 
Pharmacokinetic 
and 
Pharmacodynamic 
Assessments 
Pharmacokinetic Assessments 
On Day 1, total and unbound plasma samples for PLN-74809 pharmacokinetic (PK) 
analysis will be obtained predose and at 2, 4, and 6 hours postdose. 
At steady-state, total and unbound plasma samples for PLN-74809 PK analysis will be 
obtained predose and at least 2 hours postdose at Weeks 4 and 12. 
Pharmacodynamic Assessments 
PET/MRI Imaging for the Assessment of Type 1 Collagen Deposition 
All PET/MRI will be performed at the Martinos Center for Biomedical Imaging at 
Massachusetts General Hospital. PET imaging will be performed at prespecified times 
as indicated in the Schedule of Events. Blood samples will be obtained prior to each 
PET/MRI and will be stored for future analyses. The total amount of radiation 
exposure from the PET/MRI is equal to a whole-body exposure up to 22 mSv (11 mSv 
per administration of 68GaCBP8). 
MRI for the Assessment of PET/MRI Relationship 
All participants will undergo dynamic contrast-enhanced MRI during each PET/MRI 
session. This will be performed using gadoterate meglumine at a predefined weight-
base dose and injection rate, as detailed in the study’s Radiology Manual. 
Biomarkers in Urine, Plasma, and Serum 
Urine, plasma and serum samples will be obtained at predetermined times as indicated 
in the Schedule of Events. These samples will be used to measure specific proteins, 
peptides, metabolites and/or messenger ribonucleic acid (mRNA) transcripts that may 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 6  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
be elevated in patients with inflammatory/fibrotic disease or act as pharmacodynamic 
(PD) markers that may change with inhibition of αvβ6. 
Pharmacogenomic Assessments 
A whole blood sample for deoxyribonucleic acid (DNA) isolation will be collected 
before dosing on Day 1 from each participant in the study. 
Exploratory Efficacy 
Assessments: 
Spirometry 
Absolute FVC volume and FVC percent of predicted will be assessed by spirometry at 
screening and at the timepoints specified in the Schedule of Events. FEV1 will be 
assessed by spirometry at screening. 
Patient-reported Outcome (PRO) 
Study participants will respond to a VAS for cough severity at the timepoints specified 
in the Schedule of Events. 
Safety Assessments: 
Open ended adverse event (AE) inquiry; clinical chemistry and hematology; vital 
signs; 12-lead ECG 
Sample Size 
Justification: 
The sample size of approximately 12 participants (8 participants receiving 160 mg 
PLN-74809 and 4 receiving placebo) is expected to provide a meaningful evaluation of 
PLN-74809 safety, tolerability and PK in the target population, and add to the data of 
approximately 21 participants planned to be evaluated at this dose level in an ongoing 
multicenter, dose ranging Phase 2a study (PLN-74809-IPF-202). 
Statistical Methods: 
Analysis Populations 
Safety Population: All randomized participants who receive at least one dose of study 
drug will be included in the safety analyses. 
PK Analysis Population: All randomized participants who have sufficient PLN-74809 
concentration data for PK calculation will be included in the PK analyses.  
PD Analysis Population: All randomized participants who receive any amount of study 
drug and who have results from Baseline and from at least one post-baseline PET/MRI 
scan or PD assessment will be included in the PD analyses. 
Primary Endpoint: PD 
Quantification of type 1 collagen in the lung following 12 weeks of treatment, as 
assessed by changes from Baseline in 68Ga-CBP8 PET/MRI tracer uptake patterns. 
PET/MRI scans will be interpreted by American Board of Nuclear Medicine (ABNM)-
certified nuclear medicine physicians in an unblinded manner. Lung contours will be 
generated from baseline and post-treatment PET/MRI. Mean and maximum 
standardized uptake value (SUV) measurements of contoured lungs will be calculated 
using MIMS software, by analyzing the uptake values of 68Ga-CBP8 PET/MRI within 
the lung, and by comparing values from the baseline and post-treatment scans. 
Numerical and graphical results will be presented by dose.  
In addition, relationships between PK and type 1 collagen deposition, as well as 
between MRI and PET imaging, may be evaluated in an exploratory fashion and 
presented in a graphical manner 
Secondary Endpoint: Safety 
Safety data from all participants who received at least one dose of study drug will be 
incorporated into the final safety analysis. 
Exploratory Endpoints 
PK and PD 
Plasma PLN-74809-versus-time profiles (with plasma concentrations on both a log 
and linear scale) will be plotted for each participant. Non-compartmental analysis will 
be used to calculate PK parameters as appropriate. 
Relationships between PK and type 1 collagen deposition, as well as between MRI and 
PET imaging, may be evaluated in an exploratory fashion and presented in a graphical 
manner. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 7  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Urine, plasma, and serum samples will be analyzed for biomarkers (presence or actual 
concentration). These samples will be used to determine the levels of these markers in 
participants, the relationship between these markers, and the level of PET tracer uptake 
(type 1 collagen deposition) in the lung. 
 
Efficacy 
Percent of predicted FVC and volume will be assessed using the standard spirometry 
procedure at the Chest Clinic at Massachusetts General Hospital and presented as 
absolute values and as percent of predicted values. Baseline FVC will be the average 
of the screening and Day 1 determinations. End-of-study FVC will be the average of 
Week 12 and Week 14 determinations. 
For PRO, cough VAS will be completed at the timepoints specified in the Schedule of 
Events. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 8  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
TABLE OF CONTENTS 
CLINICAL TRIAL PROTOCOL .......................................................................................... 1 
PLN-74809-IPF-205 .............................................................................................................. 1 
SYNOPSIS............................................................................................................................ 2 
TABLE OF CONTENTS ...................................................................................................... 8 
LIST OF IN-TEXT TABLES .............................................................................................. 11 
LIST OF APPENDICES ..................................................................................................... 11 
LIST OF ABBREVIATIONS .............................................................................................. 12 
1 
INTRODUCTION ............................................................................................. 15 
1.1 
Summary of Clinical Development ............................................................... 15 
1.1.1 
Completed Phase 1 Studies ............................................................... 15 
1.1.2 
Ongoing Phase 1 Study PLN-74809-104 ........................................... 16 
1.1.3 
Ongoing Phase 2 studies ................................................................... 16 
1.2 
Study Rationale for PLN-74809-IPF-205 ..................................................... 17 
2 
STUDY OBJECTIVES ...................................................................................... 19 
2.1 
Primary Objective ........................................................................................ 19 
2.2 
Secondary Objectives ................................................................................... 19 
2.3 
Exploratory Objectives ................................................................................. 19 
3 
INVESTIGATIONAL PLAN............................................................................. 20 
3.1 
Overall Study Design and Plan ..................................................................... 20 
3.2 
Rationale for PLN-74809 Doses and Control Group ..................................... 20 
3.3 
Study Duration ............................................................................................. 21 
4 
STUDY POPULATION SELECTION............................................................... 22 
4.1 
Study Population .......................................................................................... 22 
4.2 
Inclusion Criteria .......................................................................................... 22 
4.3 
Exclusion Criteria......................................................................................... 23 
5 
STUDY DRUG AND ACCOUNTABILITY ..................................................... 26 
5.1 
Description of Study Drug ............................................................................ 26 
5.1.1 
Study Drug ....................................................................................... 26 
5.1.2 
Placebo ............................................................................................. 26 
5.1.3 
PET Tracer ....................................................................................... 26 
5.2 
Packaging and Labeling ............................................................................... 26 
5.3 
Storage and Accountability........................................................................... 26 
5.4 
Treatment Compliance ................................................................................. 26 
6 
STUDY TREATMENTS ................................................................................... 28 
6.1 
Description of Treatments ............................................................................ 28 
6.2 
Dose Modifications and Interruptions ........................................................... 28 
6.3 
Selection and Timing of Dose for Each Participant ....................................... 28 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 9  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
6.4 
Method of Assigning Participants to Treatment Groups ................................ 29 
6.5 
Blinding ....................................................................................................... 29 
6.6 
Concomitant Therapy ................................................................................... 29 
6.6.1 
Allowed Medications ........................................................................ 29 
6.6.2 
Disallowed Medications .................................................................... 30 
6.7 
Restrictions .................................................................................................. 31 
6.7.1 
Prior Therapy .................................................................................... 31 
6.7.2 
Fluid and Food Intake ....................................................................... 31 
6.7.3 
Participant Activity Restrictions........................................................ 31 
6.7.4 
Contraception ................................................................................... 31 
7 
STUDY PROCEDURES .................................................................................... 33 
7.1 
Informed Consent ......................................................................................... 33 
7.2 
Medical History............................................................................................ 33 
7.3 
Demographic Information ............................................................................ 33 
7.4 
Physical Examination ................................................................................... 33 
7.5 
Vital Signs ................................................................................................... 33 
7.6 
Electrocardiograms....................................................................................... 33 
7.7 
Clinical Laboratory Tests ............................................................................. 34 
7.7.1 
Laboratory Parameters ...................................................................... 34 
7.7.2 
Sample Collection, Storage, and Shipping......................................... 35 
7.8 
Dispensing Study Drug................................................................................. 35 
7.9 
Pharmacokinetic Assessments ...................................................................... 36 
7.10 
Pharmacodynamic Assessments ................................................................... 36 
7.10.1 
PET/MRI Imaging for the Assessment of Type 1 Collagen 
Deposition ........................................................................................ 36 
7.10.2 
MRI for the Assessment of PET/MRI Relationship ........................... 36 
7.10.3 
Biomarkers in Urine, Plasma, and Serum .......................................... 36 
7.11 
Pharmacogenomics....................................................................................... 37 
7.12 
Exploratory Efficacy Assessments ................................................................ 37 
7.12.1 
Spirometry ........................................................................................ 37 
7.12.2 
Patient-reported Outcome (PRO) ...................................................... 38 
7.13 
Concomitant Medication and Adverse Event Assessments ........................... 38 
7.14 
Missed Assessments ..................................................................................... 38 
7.15 
Appropriateness of Measurements ................................................................ 38 
8 
SAFETY ASSESSMENTS ................................................................................ 39 
8.1 
Timing ......................................................................................................... 39 
8.2 
Definition of an Adverse Event .................................................................... 39 
8.3 
Severity of an Adverse Event ....................................................................... 40 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 10  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
8.4 
Causal Relationship of an Adverse Event ..................................................... 40 
8.5 
Outcome....................................................................................................... 41 
8.6 
Pregnancy .................................................................................................... 41 
8.7 
Clinical Laboratory Adverse Events ............................................................. 42 
8.8 
Serious Adverse Events ................................................................................ 42 
8.8.1 
Definition of Serious Adverse Events ............................................... 42 
8.8.2 
Recording Adverse Events and Serious Adverse Events .................... 43 
8.8.3 
Reporting Serious Adverse Events .................................................... 43 
8.8.4 
Reporting SAEs to Regulatory Authorities and IRB/IEC/REB .......... 44 
9 
MONITORING AND MANAGEMENT OF ELEVATED LIVER 
BIOCHEMISTRY TESTS ................................................................................. 45 
10 
MONITORING AND MANAGEMENT OF ECG-RELATED 
ABNORMALITIES ........................................................................................... 48 
11 
EARLY DISCONTINUATION OF STUDY OR INDIVIDUAL 
PARTICIPANTS ............................................................................................... 51 
12 
PLANNED STATISTICAL METHODS............................................................ 52 
12.1 
General Considerations ................................................................................ 52 
12.2 
Determination of Sample Size ...................................................................... 52 
12.3 
Analysis Populations .................................................................................... 52 
12.4 
Demographics and Baseline Characteristics .................................................. 52 
12.5 
Primary Endpoints ........................................................................................ 52 
12.5.1 
Primary Pharmacodynamic Endpoint ................................................ 52 
12.6 
Secondary Endpoints .................................................................................... 53 
12.6.1 
Secondary Safety Endpoint ............................................................... 53 
12.7 
Exploratory Endpoints .................................................................................. 54 
12.7.1 
Exploratory Pharmacodynamic/Pharmacokinetic Endpoints .............. 54 
12.7.2 
Exploratory Efficacy Endpoints ........................................................ 54 
12.7.2.1 
Forced Vital Capacity (FVC) ................................................... 54 
12.7.2.2 
Patient-reported Outcome (PRO).............................................. 55 
12.8 
Other Assessments or Analyses .................................................................... 55 
12.9 
Interim Analysis ........................................................................................... 55 
13 
QUALITY CONTROL AND ASSURANCE ..................................................... 56 
14 
ADMINISTRATIVE CONSIDERATIONS ....................................................... 57 
14.1 
Institutional Review Board, Independent Ethics Committee or Research 
Ethics Board Approval ................................................................................. 57 
14.2 
Ethical Conduct of the Study ........................................................................ 57 
14.3 
Participant Information and Consent............................................................. 57 
14.4 
Participant Confidentiality ............................................................................ 58 
14.5 
Study Monitoring ......................................................................................... 58 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 11  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
14.6 
Case Report Forms and Study Records ......................................................... 59 
14.7 
Adjudication Committee .............................................................................. 59 
14.8 
Retention of Data ......................................................................................... 59 
14.9 
Financial Disclosure ..................................................................................... 59 
14.10 
Publication and Disclosure Policy ................................................................ 59 
15 
REFERENCE LIST ........................................................................................... 61 
Appendix 1 
 Schedule of Events .......................................................................... 63 
Appendix 2 
 Sponsor Signature ............................................................................ 66 
Appendix 3 
 Investigator’s Signature ................................................................... 67 
 
LIST OF IN-TEXT TABLES 
Table 1 
List of Laboratory Tests.......................................................................... 35 
Table 2 
Reference Ranges for Key Laboratory Liver Function Tests ................... 45 
Table 3 
CTCAE Version 5 Grading for Electrocardiogram QT Corrected 
Interval Prolonged .................................................................................. 48 
 
LIST OF APPENDICES 
Appendix 1 
 Schedule of Events ................................................................................ 63 
Appendix 2 
 Sponsor Signature .................................................................................. 66 
Appendix 3 
 Investigator’s Signature ......................................................................... 67 
 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 12  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
LIST OF ABBREVIATIONS 
ABNM 
American Board of Nuclear Medicine 
ADL 
activities of daily living 
AE 
adverse event 
ALAT 
Latin American Respiratory Society 
ALP 
alkaline phosphatase 
ALT 
alanine aminotransferase 
ANA 
antinuclear antibody 
anti-LC1 
anti-liver cytosolic antigen type 1 (antibody) 
anti-LKM1 
anti-liver-kidney microsome type 1 (antibody) 
anti-SMA 
anti-smooth muscle antibody (antibody) 
ARDS 
acute respiratory distress syndrome 
AST 
aspartate aminotransferase  
ATS 
American Thoracic Society 
AUC0-24 
area under the plasma concentration-time curve from time zero to 24 hours 
BMI 
body mass index 
BRCP 
breast cancer resistance protein 
Cmax 
maximum observed drug concentration 
COL1A1 
collagen type 1 alpha 1 
COVID-19 
coronavirus disease 2019 
CRO 
contract research organization 
CT 
computerized tomography 
CTCAE 
Common Terminology Criteria for Adverse Events 
CYP 
cytochrome P450 
DILI 
drug induced liver injury 
DLco 
diffusing capacity for carbon monoxide 
DNA 
deoxyribonucleic acid 
ECG 
electrocardiogram 
eCRF 
electronic case report form 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 13  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
EDC 
electronic data capture 
ERS 
European Respiratory Society 
ET 
early termination 
FDA 
Food and Drug Administration 
FEV1 
forced expiratory volume during the first seconds of the forced breath 
FSH 
follicle-stimulating hormone 
FVC 
forced vital capacity 
GCP 
Good Clinical Practice 
GDPR 
General Data Protection Regulation 
HIPAA 
Health Information Portability and Accountability Act 
HRCT 
high-resolution computerized tomography 
IC50 
50% inhibitory concentration 
IC80 
80% inhibitory concentration 
ICF 
informed consent form 
ICH 
International Council on Harmonisation  
IEC 
independent ethics committee 
IgG-1 
immunoglobulin G1 
INR 
international normalized ratio 
IPF 
idiopathic pulmonary fibrosis 
IRB 
institutional review board 
IRT 
interactive response technology 
IV 
intravenous 
JRS 
Japanese Respiratory Society 
MAD 
multiple ascending dose 
MATE1 
multidrug and toxin extrusion transporter 
mCI 
millicurie 
MedDRA 
Medical Dictionary for Regulatory Activities 
mRNA 
messenger ribonucleic acid 
MRI 
magnetic resonance imaging 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 14  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
mSv 
millisievert 
NOAEL 
no observed adverse effect level 
OATP 
organic anion transporting polypeptide 
P-gp 
P glycoprotein 
PCLS 
precision cut lung slices 
PD 
pharmacodynamic(s) 
PDE-5 
phosphodiesterase -5 
PET 
positron emission tomography 
PIPEDA 
Personnel Information Protection and Electronic Documents Act 
PK 
pharmacokinetic(s) 
PRO 
patient-reported outcome 
PSC 
primary sclerosing cholangitis 
QD 
once daily 
QLF 
quantitative lung fibrosis 
QTc 
QT interval corrected for heart rate 
QTcF 
QT interval corrected for heart rate using Fridericia's formula 
REB 
research ethics board 
SAD 
single ascending dose 
SAE 
serious adverse event 
SAP 
statistical analysis plan 
SoC 
standard of care 
SMAD2/3 
family of proteins similar to the gene products of the Drosophila gene 'mothers 
against decapentaplegic' (Mad) and the C. elegans gene Sma, 2 or 3 
SpO2 
peripheral capillary oxygen saturation 
SUV 
standardized uptake value 
TEAE 
treatment-emergent adverse event 
TGF-β 
transforming growth factor beta 
ULN 
upper limit of normal 
US 
United States 
VAS 
visual analog scale 
 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 15  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
1 
INTRODUCTION 
Pliant Therapeutics Inc. (Pliant) is developing PLN-74809 for the treatment of idiopathic 
pulmonary fibrosis (IPF), treatment of primary sclerosing cholangitis (PSC), and treatment of 
acute respiratory distress syndrome (ARDS) associated with at least severe coronavirus 
disease 2019 (COVID-19).  
IPF is the most common interstitial lung disease usually observed in the elderly characterized 
by dyspnea and progressive loss of lung function leading to death, with median survival of 
3.8 years after diagnosis based on 2014 data in the United States (US). The hallmark 
honeycomb appearance of IPF on high-resolution computerized tomography (HRCT) is the 
result of extensive fibrosis (Lederer and Martinez, 2018). Although not completely 
understood, IPF appears to be a response to alveolar epithelial injury with the resultant 
fibrosis mediated by growth factors (Kreuter et al, 2015; Wilson and Raghu, 2015) and 
propagated by myofibroblasts. As has also been indicated to be the case for other fibrotic 
conditions, signaling mediated by αv integrins is central to the control of fibrosis in the lungs. 
Specific roles proposed for αvβ6 in epithelial cells and αvβ1 in myofibroblasts for induction of 
fibrosis are summarized in the Investigator’s Brochure for PLN-74809. 
PLN-74809 is a small molecule and a selective dual inhibitor of αvβ6 and αvβ1 integrins: 
50% inhibitory concentration (IC50) 5.7 nM and 3.4 nM, respectively, in an in vitro ligand-
binding assay (protein-free); IC50 30 nM and 19.5 nM (10.2 nM and 6.6 nM unbound), 
respectively, in an in vitro co-culture assay of transforming growth factor beta (TGF-β) 
activation. PLN-74809 reduced collagen synthesis in mice with bleomycin-induced lung 
injury, a commonly used experimental model for IPF (Moeller et al, 2008). In ex vivo human 
IPF lung tissue (precision cut lung slices), treatment with PLN-74809 significantly decreased 
collagen type 1 alpha 1 (COL1A1) messenger ribonucleic acid (mRNA) expression levels 
after a 3-day incubation period, providing an indication of antifibrotic activity in IPF. Mice 
completely deficient for αvβ6 function live a normal lifespan (Horan et al, 2008), suggesting 
that even full inhibition of such integrins is well tolerated. 
1.1 
Summary of Clinical Development 
To date, 4 Phase 1 studies in healthy participants are completed. One Phase 1 and 4 Phase 2 
studies are currently ongoing. All data from these studies are supportive of the continued 
clinical development of PLN-74809 across the current indications.  
1.1.1 
Completed Phase 1 Studies 
In the first-in-human evaluation of PLN-74809 (PLN-74809-P1-01), a total of 71 healthy 
participants were exposed to PLN-74809 for up to 14 days, with single and multiple doses 
ranging from 10 to 75 mg. Overall, the study showed that single ascending dose (SAD) and 
multiple ascending dose (MAD) administration of PLN-74809 was well tolerated at all dose 
levels, with no apparent relationship between frequency or severity of adverse events (AEs) 
to PLN-74809 doses or to treatment duration.  

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 16  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
In Study PLN-74809-P1-03, a total of 13 healthy participants were exposed to PLN-74809 at 
20 and 40 mg for up to 7 days. Overall, the study showed that PLN-74809 was well tolerated 
and led to suppression of TGF-β signaling in the lung at the 40 mg dose.  
In Study PLN-74809-106 (Relative Bioavailability Study), a total of 24 healthy participants 
were exposed to a single dose of 40 mg PLN-74809 in either oral solution or tablet 
formulation. There were no notable differences in the safety and tolerability of the 
2 formulations.  
In Study PLN-74809-107 (mass balance study), 12 healthy participants received a single 
40 mg dose of 14C-labelled PLN-74809. PLN-74809 was excreted mainly via the feces, and 
was safe and well tolerated. One minor metabolite was detected in plasma. 
Overall, all the completed studies showed that SAD and MAD administration of PLN-74809 
was safe and well tolerated. 
Please refer to the Investigator’s Brochure for additional detailed information on these 
studies. 
1.1.2 
Ongoing Phase 1 Study PLN-74809-104 
Study PLN-74809-104 is a continued evaluation of higher single and multiple doses of 
PLN-74809 in healthy participants. To date, participants have received single doses of 
PLN-74809 up to 640 mg and multiple doses of PLN-74809 up to 320 mg. 
PLN-74809 showed a favorable safety and tolerability profile after up to 7 days of treatment, 
with no new safety concerns observed during this dose-escalation study. There were no 
clinically significant alterations in vital signs, electrocardiogram (ECG) or laboratory 
parameters across either the SAD or MAD cohorts indicative of a safety signal. There were 
no deaths reported during or after the study period. 
Please refer to the Investigator’s Brochure for additional detailed information on this study. 
(Note that analysis of data from single doses greater than 320 mg and multiple doses greater 
than 160 mg is ongoing.) 
1.1.3 
Ongoing Phase 2 studies 
Four Phase 2 studies evaluating doses of PLN-74809 are ongoing. 
Study PLN-74809-IPF-201 is a Phase 2a open-label study to evaluate the effect of 
PLN-74809 on αvβ6 receptor occupancy using positron emission tomography (PET) imaging 
in participants with IPF evaluating single doses ranging from 60 to 320 mg. Evaluation of 
target engagement and the safety and tolerability of PLN-74809 is currently ongoing and no 
new safety concerns have been identified. 
Study PLN-74809-IPF-202 is a Phase 2a, multicenter, 3-part, randomized, double-blind, 
dose-ranging, placebo-controlled evaluation of the safety, tolerability and pharmacokinetics 
(PK) of once daily treatment with PLN-74809 for 12 weeks in participants with IPF. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 17  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Study PLN-74809-PSC-203 is a Phase 2a, multicenter, 2-part, randomized, double-blind, 
dose-ranging, placebo-controlled evaluation of the safety, tolerability and PK of once daily 
treatment with PLN-74809 for 12 weeks in participants with PSC and suspected liver 
fibrosis.  
Study PLN-74809-ARDS-204 is a Phase 2a, multicenter, 3-part, randomized, double-blind, 
dose-ranging, placebo-controlled evaluation of the safety, tolerability and PK of once daily 
treatment with PLN-74809 for 7-14 days in participants with ARDS associated with at least 
severe COVID-19.  
At the time of protocol finalization, safety and tolerability data from these ongoing Phase 2 
studies suggest no new safety concerns.  
Please refer to the Investigator’s Brochure for additional detailed information on these 
studies. 
1.2 
Study Rationale for PLN-74809-IPF-205 
IPF is characterized by excessive type 1 collagen deposition in the lungs that replaces healthy 
parenchymal tissue with collagen-rich scar. As the disease advances, progressive 
architectural distortion and dysfunction ensues resulting in often subtle but limiting 
breathlessness, fatigue and cough. TGF-β is an important pleotropic cytokine that is a key 
regulator of tissue fibrogenesis in both normal wound repair and pathologic fibroproliferative 
diseases such as IPF. TGF-β is constitutively secreted and bound within the extracellular 
matrix in its latent or inactive form. Release or activation of latent TGF-β may occur with 
proteolytic cleavage via plasmin or matrix metalloproteinases, or interaction with several 
different integrins, namely αvβ6 (expressed on epithelial cells) and αvβ1 (expressed on 
fibroblasts) in the lung. In IPF, αvβ6 and αvβ1 expression are increased with a resultant 
increase in TGF-β signaling and its downstream pro-fibrotic targets, notably COL1A1.  
PLN-74809 is an oral, once-daily, dual-selective inhibitor of αvβ6 and αvβ1 integrins in 
development for the treatment of IPF, with orphan drug designation granted by the US Food 
and Drug Administration (FDA). PLN-74809 was generally well tolerated in over 
180 participants treated to date in clinical studies, with single doses up to 320 mg and 
multiple doses up to 160 mg once daily; additionally, single doses of up to 640 mg and 
multiple doses of 320 mg were evaluated and preliminary blinded data have not identified 
new safety concerns. The binding of PLN-74809 inhibits the interaction of these integrins 
with latency associated peptide and blocks the release of free TGF-β into the extracellular 
matrix for subsequent binding to its receptor and activation of profibrotic pathways, 
including collagen synthesis. Precision cut lung slices (PCLS) generated from IPF patient 
lungs collected during transplant were used to evaluate the ability of PLN-74809 to block 
TGF-β activation and collagen gene expression in fibrotic human lung tissue ex vivo. 
Following 7 days incubation with PLN-74809 (200 nM or 1820 nM), collagen gene 
expression and SMAD2 phosphorylation (a marker of TGF-β signaling) in IPF patient PCLS 
were significantly reduced by approximately 50%. In vivo efficacy studies of PLN-74809 
were also performed using the bleomycin mouse model of pulmonary fibrosis. In a 
prophylactic treatment study (PLN-74809 administered orally or via minipump from 1 to 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 18  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
14 days post-bleomycin challenge), PLN-74809 significantly decreased Ashcroft score, total 
hydroxyproline levels, new collagen synthesis, and phosphorylation of SMAD3 in lung 
tissue, confirming inhibition of collagen deposition via a reduction in TGF-β signaling.  
Similar effects were observed with therapeutic treatment with PLN-74809 in the bleomycin 
model (oral administration from 7 to 21 days post-bleomycin challenge). Lung 
hydroxyproline levels were significantly reduced and morphometric analysis of lung tissue 
showed a dose-dependent and significant reduction in interstitial fibrillar collagen deposition 
in mice treated with PLN-74809. These data suggest that PLN-74809 is expected to decrease 
new collagen formation in the lungs of patients with IPF, which will be evaluated in this 
study.  
68Ga-CBP8, a PET radiotracer that binds specifically to type 1 collagen, has previously been 
shown to detect and quantify elevated collagen levels in patients with IPF compared to 
healthy individuals, particularly in the subpleural regions of the lung where fibrosis is known 
to be prominent (Montesi et al, 2019). Importantly, increased collagen tracer signal was also 
noted in radiographically normal areas on computerized tomography (CT) prior to 
architectural distortion, indicating the 68Ga-CBP8 probe may be more sensitive than HRCT 
in detecting active and/or early fibrosis. Furthermore, 68Ga-CBP8 uptake in mouse lungs has 
been shown to correlate with levels of fibrosis following injury, with data suggesting that the 
tracer more readily binds newly formed collagen in active disease than established mature 
collagen. PLN-74809 consistently, and in a dose-dependent manner, reduced COL1A1 
expression in murine models of bleomycin lung injury and PCLS. These findings suggest that 
68Ga-CBP8 may be an effective tool for measuring disease activity (e.g., recently deposited 
pulmonary collagen levels) and therefore a powerful tool for evaluating efficacy of 
anti-fibrotic agents such as PLN-74809 in clinical studies. Therefore, in the proposed 
12-week study of PLN-74809, the measurement of 68Ga-CBP8 PET ligand will serve two 
functions; changes over time will provide an exploratory endpoint of both pharmacodynamic 
(PD) activity and efficacy (reduced collagen levels) of PLN-74809.  
To complement the evaluation of antifibrotic effects in the proposed PLN-74809-IPF-205 
study, ongoing Phase 2 studies conducted in participants with IPF (PLN-74809-IPF-202) or 
PSC (PLN-74809-PSC-203) will assess the safety and tolerability of PLN-74809, along with 
exploratory endpoints relevant to fibrosis. In the PLN-74809-IPF-202 study, exploratory 
efficacy endpoints will be assessed, including change in forced vital capacity (FVC) and 
quantitative lung fibrosis (QLF) from baseline following 12 weeks of treatment with 
PLN-74809. These established (FVC) and exploratory assessments of progressive disease 
and collagen deposition in IPF will complement the current study, which will be first of its 
kind to quantify changes in type 1 collagen in the lungs of participants with IPF following 
12 weeks of treatment with PLN-74809 using 68Ga-CBP8 PET/ magnetic resonance imaging 
(MRI) tracer uptake. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 19  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
2 
STUDY OBJECTIVES  
2.1 
Primary Objective  
• Quantification of type 1 collagen in the lung following 12 weeks of treatment with 
PLN-74809, as assessed by changes from Baseline in 68Ga-CBP8 PET/MRI tracer uptake 
patterns 
 
2.2 
Secondary Objectives 
• Assessment of the safety and tolerability of PLN-74809 in IPF participants 
 
2.3 
Exploratory Objectives 
• Relationship between PLN-74809 systemic exposure and PET imaging and biomarkers in 
IPF participants 
• FVC: absolute FVC volume and FVC as percent of predicted as assessed by spirometry 
• Patient-reported outcome (PRO): a visual analog scale (VAS) for cough severity 
 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 20  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
3 
INVESTIGATIONAL PLAN 
3.1 
Overall Study Design and Plan 
This is a Phase 2a, single-center, randomized, double-blinded, placebo-controlled study to 
evaluate type 1 collagen deposition in the lungs following once-daily (QD) treatment with 
160 mg PLN-74809 for 12 weeks in participants with IPF.  
The study consists of an up to 28-day screening period, a 12-week treatment period, and a 
2-week (±3 days) post treatment follow-up period.  
Potential participants who provide written informed consent will be screened for study 
eligibility up to 28 days before administration of the first dose of study drug. Approximately 
12 eligible participants will be randomized in a 2:1 ratio (160 mg PLN-74809 vs placebo; 
8 receiving PLN-74809 and 4 receiving placebo) on Day 1 (Visit 3). Study treatment will be 
administered once daily for 12 weeks. Randomization will be stratified by use of standard of 
care (SoC) IPF therapy with pirfenidone or nintedanib (SoC use; yes or no). 
68Ga-CBP8 PET/MRI scans will be conducted within 7 days prior to baseline and at or within 
7 days prior to Week 12, as indicated in the Schedule of Events (Appendix 1). 
Participants who discontinue study drug for safety reasons prior to completion of 12 weeks of 
treatment will be encouraged to remain in the study to complete all remaining assessments; if 
this is not feasible, they will be asked to return to the clinic for an Early Termination (ET) 
visit for follow-up evaluations. If a participant elects to withdraw from the study after the 
6th week of randomization, an end of participation 68Ga-CBP8 PET/MRI will be offered to 
the participant to enhance appropriate data capture. 
Potential acute exacerbations, respiratory-related hospitalizations, and/or respiratory-related 
deaths will be reviewed by an adjudication committee. 
3.2 
Rationale for PLN-74809 Doses and Control Group 
This study will quantify type 1 collagen expression in the lung following PLN-74809 
exposure, as assessed by changes from baseline in 68Ga-CBP8 PET/MRI tracer uptake 
patterns following 12 weeks of treatment with 160 mg of PLN-74809, administered once 
daily. Available safety, tolerability and PK data from Study PLN-74809-104 and Study 
PLN-74809-IPF-202 (i.e., Part B evaluating 40 mg once daily for 12 weeks; Part C has 
initiated and will evaluate doses of 80 or 160 mg once daily, in parallel groups) support 
evaluation of a dose of 160 mg, which is expected to achieve the target 80% inhibitory 
concentration (IC80) for αvβ6 and αvβ1 integrin-mediated TGF-β1 activation (IC80 
∼2300 ng/mL) for approximately 8 hours and the target IC50 (∼500 ng/mL) for 24 hours.  
PLN-74809 160 mg is the highest dose evaluated in the ongoing dose ranging Study 
PLN-74809-IPF-202. 
To complement prior and ongoing safety evaluations, the safety, tolerability and PK of 
PLN-74809 in participants with IPF, with or without co-administration with SoC 
(pirfenidone or nintedanib) will also be assessed. The proposed randomized, double-blind 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 21  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
study design allows a reduction in bias in the assessment of type 1 collagen expression and of 
drug safety and tolerability. Stratification for background treatment with SoC will ensure a 
similar proportion of participants on SoC in each treatment group. The proposed sample size 
and 12-week treatment duration are expected to provide meaningful PK information in the 
IPF population, comparing PLN-74809 to placebo. The proposed randomization strategy in 
this exploratory study, 2:1 (PLN-74809 : placebo), will allow for determination of change in 
type 1 collagen deposition over 3 months and the impact of PLN-74809, which is expected to 
lead to decreased type 1 collagen expression within the lung based on localized inhibition of 
TGF-β signaling.  
The evaluation of PLN-74809 160 mg QD is supported by safety and PK data evaluating 
multiple doses of 160 mg from study PLN-74809-104. In Study PLN-74809-104, 
PLN-74809 showed a favorable safety and tolerability profile in healthy participants after 
single doses of up to 320 mg and after 7 days of treatment at doses of up to 160 mg, as 
described in the Investigator's Brochure; additionally, single doses of up to 640 mg and 
multiple doses of 320 mg were evaluated and preliminary blinded data have not identified 
new safety concerns (Section 1.1.2). The safety margins determined after single doses of up 
to 320 mg and multiple doses up to 160 mg were calculated using the no observed adverse 
effect level (NOAEL) observed in monkeys for both area under the plasma concentration-
time curve from time zero to 24 hours (AUC0-24) and maximum observed drug concentration 
(Cmax) for the measured unbound concentrations of PLN-74809. At all dose levels studied, 
there was a substantial margin between the unbound AUC0-24 and the monkey NOAEL. See 
PLN-74809 Investigator’s Brochure for more details.  
 
The evaluation of PLN-74809 is also supported by safety and PK data from participants with 
IPF enrolled in study PLN-74809-IPF-202; in Part B, PLN-74809 showed a favorable safety 
and tolerability profile after daily doses of 40 mg for up to 12 weeks. No related 
treatment-emergent serious adverse events (SAEs) were reported, no new safety concerns 
were identified to date and the DSMB recommended continuation to Part C, evaluating 
PLN-74809 doses of 80 mg and 160 mg QD, without any modifications.  
Taken together, the accumulating data from completed and ongoing Phase 1 and Phase 2 
evaluations of PLN-74809 continue to highlight its favorable safety and tolerability profile 
and support the evaluation of the dose of 160 mg QD administered for 12 weeks in this study.   
3.3 
Study Duration  
Participants will be on study for up to 18 weeks (4 weeks of screening, 12 weeks of treatment 
with study drug and 2 weeks of follow up). 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 22  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
4 
STUDY POPULATION SELECTION 
4.1 
Study Population 
This study intends to enroll participants with IPF, with a life-expectancy of at least 6 months, 
who may or may not be receiving treatment with pirfenidone or nintedanib, and who 
otherwise do not present with other major health conditions that could confound the study 
outcomes.  
4.2 
Inclusion Criteria 
Each participant must meet the following criteria to be enrolled in this study: 
1. Participants, aged 40 years or older 
2.  Diagnosis of IPF, within 8 years prior to screening, according to the American 
Thoracic Society (ATS)/ European Respiratory Society (ERS)/ Japanese Respiratory 
Society (JRS)/ Latin American Respiratory Society (ALAT) 2018 guidelines 
(Raghu et al, 2018)  
Note: If IPF diagnosis is within > 3 to ≤ 8 years at screening, the participant must 
have evidence of progression within the last 24 months, as defined by decline in 
FVC percent predicted based on a relative decline of ≥ 5%   
3. FVC percent of predicted ≥ 45%; historical FVC for entry in the study is permitted if 
within 1 month of screening 
4. Diffusing capacity for carbon monoxide (DLco) (hemoglobin-adjusted) ≥ 30%; 
historical DLco for entry in the study is permitted if within 1 month of screening 
5. Participants currently receiving treatment for IPF with nintedanib or pirfenidone are 
allowed, provided these drugs have been given at a stable dose for at least 3 months 
before the Screening Visit and are expected to remain unchanged during the study 
(stable dose is defined as the highest dose tolerated by the participant during 
≥ 3 months) 
6. Estimated glomerular filtration rate ≥ 50 mL/min, according to the Cockcroft-Gault 
equation 
7. Female participants of non-childbearing potential must be either surgically sterile or 
postmenopausal (refer to Section 6.7.4)  
8. Female participants of childbearing potential must use a contraceptive method with a 
failure rate of <1% per year or remain abstinent (refrain from heterosexual 
intercourse) during the treatment period and for 1 month after the last dose of study 
treatment (refer to Section 6.7.4). 
9. Male participants with female partners of childbearing potential must agree to use 
contraceptive measures (refer to Section 6.7.4) or remain abstinent (refrain from 
heterosexual intercourse) during the treatment period and for at least 3 months after 
the last dose of study treatment. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 23  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
10. Participants must agree to abstain from sperm or egg donation for the duration of the 
study, through to 3 months or 1 month, respectively, after administration of the last 
dose of study drug 
11. Able to understand the purpose of the study and its procedures and to sign a written 
informed consent form (ICF) 
4.3 
Exclusion Criteria 
Participants who meet any of the following criteria will be excluded from the study. 
1. Hypersensitivity to PLN-74809 or to any of the excipients to PLN-74809 
2. Not a suitable candidate or unlikely to comply with study requirements, in the opinion of 
the Investigator 
3. Receiving any nonapproved agent intended for treatment of fibrosis in IPF  
4. Forced expiratory volume during the first seconds of the forced breath (FEV1)/FVC ratio 
< 0.7 at screening 
5. Clinical evidence of active infection, including but not limited to bronchitis, pneumonia 
or sinusitis that can affect FVC measurement during screening or at randomization 
6. Any other condition that prevents the correct assessment of spirometry performance (e.g., 
a broken rib or chest pain of other origin that prevents adequate forced breathing) 
7. Known acute IPF exacerbation or suspicion by the Investigator of such, within 6 months 
of screening 
8. Severe pulmonary hypertension 
9. Smoking of any kind (not limited to tobacco) within 3 months prior to screening, as 
documented in the medical history, or unwilling to avoid smoking throughout the study 
10. Lower respiratory tract infection requiring antibiotics within 4 weeks prior to screening 
and/or during the screening period 
11. History of malignancy within the past 5 years or ongoing malignancy other than basal 
cell carcinoma, resected noninvasive cutaneous squamous cell carcinoma, or treated 
cervical carcinoma in situ 
12. End-stage liver disease 
13. Renal impairment or end-stage kidney disease requiring dialysis 
14. History of unstable or deteriorating cardiac or pulmonary disease (other than IPF) within 
the 6 months prior to screening, including but not limited to the following:  
a. Unstable angina pectoris or myocardial infarction  
b. Congestive heart failure requiring hospitalization  
c. Uncontrolled clinically significant arrhythmias (e.g., resulted in health care utilization 
or hospitalization) 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 24  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
15. Any clinically relevant ECG abnormalities, including but not limited to, QT interval 
corrected for heart rate using Fridericia's formula (QTcF) > 450 msec for males or 
> 460 msec for females at the Screening Visit (including Day -1) or prior to 
administration of the initial dose of study drug 
16. Any medical condition that, in the opinion of the Investigator, may make the candidate 
not suitable for the study 
17. History of anaphylaxis to intravenous (IV) drugs 
18. Any of the following liver function test criteria above specified limits: total bilirubin 
>1.5× the upper limit of normal (ULN); aspartate aminotransferase (AST) or alanine 
aminotransferase (ALT) >3× ULN; alkaline phosphatase > 2.5× ULN.  
Note: participants currently receiving nintedanib or pirfenidone as IPF SoC treatment, 
who have previously presented any liver function test elevations associated with 
nintedanib or pirfenidone treatment greater than that described above or resulting in 
dose reduction, treatment interruption, or discontinuation are not eligible. 
19. Any of the following at screening: hemoglobin < 10.0 g/dL, neutrophils < 1500 /mm3, or 
platelets < 100,000 /mL 
20. Electrical implants such as cardiac pacemaker or perfusion pump 
21. Ferromagnetic implants such as aneurysm clips, surgical clips, prostheses, artificial 
hearts, valves with steel parts, metal fragments, shrapnel, metallic tattoos anywhere on 
the body, tattoos near the eye, or steel implants, ferromagnetic objects such as jewelry or 
metal clips in clothing 
22. Claustrophobic reactions 
23. Research-related radiation exposure exceeds current Radiology Department guidelines 
(i.e. 50 mSv in the prior 12 months) 
24. Unable to lie comfortably on a bed inside the PET/MRI 
25. Body mass index (BMI) > 33 kg/m2 (limit of the PET/MRI table) 
26. Prior or current radiation to the thorax 
27. Pregnant or lactating female participants 
28. Male participants with pregnant female partners 
29. A medical or surgical condition known to affect drug absorption (e.g., major gastric 
surgery)  
30. Participation in a clinical study with an investigational agent in the 30 days prior to 
screening or 5 half-lives of the investigational drug, whichever is longer trial, apart from 
PLN-74809 
31. Currently receiving and expected to remain on treatment during the study with: potent 
and concomitant inhibitors or inducers of cytochrome P450 (CYP) 3A4, 2C9 or 2C19; 
potent inhibitors or inducers of P-glycoprotein (P-gp), breast cancer resistance protein 
(BCRP) or organic anion transporting polypeptide (OATP) 1B1/1B3 transporters; 
digoxin (a P-gp substrate with a narrow therapeutic window) 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 25  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
32. Daily use of phosphodiesterase-5 (PDE-5) inhibitor drugs (e.g., sildenafil, tadalafil, 
other) (Note: Intermittent use for erectile dysfunction is allowed.) 
33. Surgical procedures planned to occur during the study period 
34. Uncontrolled systemic arterial hypertension 
35. Likely to have lung transplantation during the study (being on transplantation list is 
acceptable)  
 
 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 26  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
5 
STUDY DRUG AND ACCOUNTABILITY 
5.1 
Description of Study Drug 
5.1.1 
Study Drug 
The zwitterion PLN-74809-000, and the phosphate salt PLN-74809-020 are derivatives of the 
parent form PLN-74809. Both are formulated as immediate-release tablets.  In this study, the 
phosphate form will be tested, hereafter referred to as PLN-74809. 
PLN-74809 drug product is supplied as 80-mg immediate release tablets. The PLN-74809 
tablets are manufactured by dry granulation with standard excipients (microcrystalline 
cellulose, mannitol, crospovidone, magnesium stearate, and butylated hydroxytoluene), tablet 
compression, and spray coating of tablets.  
5.1.2 
Placebo 
A corresponding matching placebo will be provided. 
5.1.3 
PET Tracer   
The 68Ga-CBP8 PET/MRI tracer is not considered a study treatment but is an investigational 
tool used during the PET procedure for obtaining the images necessary for this trial. 
[68Ga]CBP8 is given as an intravenous injection within 7 days prior to baseline and at or 
within 7 days prior to Week 12. The radiochemical dose is up to 12.9 mCi but in practice, the 
dose has averaged 5.5 mCi per subject. 
 
5.2 
Packaging and Labeling 
The PLN-74809 oral tablets will be packaged in high-density polyethylene bottles with 
desiccant canisters. Details are provided in the Pharmacy Manual. 
5.3 
Storage and Accountability 
The study drug should be stored refrigerated at 2°C to 8°C and protected from light, whether 
at the site pharmacy or at the participant’s home. 
All used and unused study medication bottles must be returned to the study site at the 
Week 4, 8, and 12 visits in order to perform accountability. 
5.4 
Treatment Compliance 
Dosing will be performed in the presence of site staff every time the participant is on site on 
dosing days. For offsite dosing, participants will be provided with a dosing log in which they 
will collect dosing information for PLN-74809 and, if applicable, nintedanib or pirfenidone 
doses taken at home. Participants should return all used and unused medication bottles to the 
site at each site visit.  

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 27  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Treatment compliance will be calculated comparing the amount of drug dispensed and drug 
returned. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 28  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
6 
STUDY TREATMENTS 
6.1 
Description of Treatments 
160 mg of PLN-74809 or matching placebo administered orally QD (2 tablets) 
PLN-74809 and matching placebo will be supplied by Pliant as a tablet for oral 
administration. Study drug will be taken once daily at approximately 24-hour intervals.  
6.2 
Dose Modifications and Interruptions 
There will be no dose modifications of the study drug. If the study drug needs to be 
interrupted for safety or tolerability issues, this should happen, as feasible, in consultation 
with the Sponsor Study Director, who together with the Investigator will assess and decide 
whether the study drug interruption should be temporary or permanent on a case by case 
basis. Participants who discontinue study drug for safety reasons prior to completion of 12 
weeks of treatment will be asked to remain in the study to complete all remaining 
assessments; if this is not feasible, then they will be asked to return to the clinic for an early 
termination visit. 
Dose modifications or interruptions of pirfenidone or nintedanib treatment may be 
implemented only for safety and tolerability reasons (e.g., liver enzyme elevation; see 
Section 9), in accordance with their corresponding prescribing information and in 
consultation with the Sponsor Study Director. This should not affect the administration of the 
study drug or the continuation of participants in the study.  
6.3 
Selection and Timing of Dose for Each Participant 
Participants will be encouraged to take their study drug at the same time of the day, each day. 
Participants will take the study drug on an empty stomach (no food for 2 hours before or 
2 hours after dosing) and will drink up to 240 mL (~1 cup of water) after swallowing the 
study drug.  
 
A dose will be considered missed if the participant cannot take the dose within 12 hours of 
their regular dosing time.  
• If a participant has missed a dose of study drug and is still within 12 hours of the time it 
is usually taken, the participant should take a dose of the missed drug as soon as possible. 
The participant may then continue the usual dosing schedule. 
• If the participant has missed a dose of study drug more than 12 hours after the time it is 
usually taken, the participant should not take the missed dose and should resume the 
usual dosing at the next scheduled time. The participant should not take a double dose to 
make up for a missed dose. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 29  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
6.4 
Method of Assigning Participants to Treatment Groups 
Approximately 12 eligible participants will be randomized in a 2:1 ratio (160 mg PLN-74809 
vs placebo). Randomization will be stratified by use of SoC IPF therapy (pirfenidone or 
nintedanib) (SoC use; yes or no). 
Assignment will be performed in a blinded manner using interactive response technology 
(IRT) based on a previously generated randomization code. Randomization will occur 
immediately prior to dosing on the morning of the first dose (Day 1). 
6.5 
Blinding 
The placebo treatment will resemble the active treatment for tablet shape, size and color. This 
ensures that the participant, Investigator, clinical site study staff, and Sponsor study team 
directly involved in trial conduct are unaware of the treatment allocation during the conduct 
of the study. The PLN-74809 or placebo will be provided as blinded kits and will be assigned 
to participants using a randomization code. 
Procedures will be in place to allow prompt breaking of the blind by the investigator if 
needed for the safety management of a participant. Unblinding at the study site for any other 
reason will be considered a protocol deviation. The investigator is strongly encouraged to 
contact the sponsor Study Director before unblinding any participant’s treatment assignment, 
but must do so within one working day after the event. A written explanation of the reason 
for unblinding should be provided to the sponsor within 24 hours of breaking the blind. Refer 
to the IRT User Guide for a description regarding how investigators may access treatment 
information via the IRT system.  
6.6 
Concomitant Therapy 
6.6.1 
Allowed Medications 
During screening, all medications including over the counter medications and herbal 
supplements taken during the 30 days prior to screening will be recorded and reviewed by the 
Investigator in consultation with the sponsor Study Director to determine whether the 
participant is suitable for inclusion. For other concomitant medications needed during the 
study conduct, the Investigator should consult with the sponsor Study Director as soon as 
feasible.  
Only treatment with approved SoC for IPF (nintedanib or pirfenidone) is allowed. These 
drugs must have been given at a stable dose for at least 3 months before initiation of 
screening and be expected to remain unchanged during the study. In addition, for participants 
receiving nintedanib or pirfenidone, the time of drug administration should be collected each 
day samples are obtained for assessing PLN-74809 PK. Treatments to address IPF disease 
symptoms, (e.g., cough, gastroesophageal reflux disease, etc.) are allowed. 
Other medications to provide reasonable patient care of comorbidities are allowed during the 
study; however, these should only be used if necessary because, at this stage of development, 
no formal drug-drug interaction studies with PLN-74809 have been performed. If used, all 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 30  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
concomitant medications including both prescription and nonprescription drugs should first 
be discussed with the Sponsor Study Director before administration. This requirement does 
not apply in the case of urgent, necessary treatment of AEs. In all cases, medications, 
including over the counter medications and herbal supplements, taken by participants during 
the course of the study will be recorded using the generic name of the medication.  
Prolonged treatment with high doses of systemic corticosteroids may induce CYP3A4 and 
reduce PLN-74809 concentrations; if such treatment is required, this must be discussed and 
approved by the Sponsor Study Director. 
PLN-74809 is a moderate inhibitor of P-gp and multidrug toxin extrusion transporter 
(MATE1). Participants who receive substrates of these transporters should be monitored for 
potential tolerability issues.  
This includes monitoring for signs and symptoms of lactic acidosis, which has been 
reported in patients receiving metformin, a substrate for MATE1. Symptoms of lactic 
acidosis include: malaise, myalgias, respiratory distress, somnolence, and abdominal pain. 
Laboratory abnormalities include elevated blood lactate levels, anion gap acidosis, increased 
lactate/pyruvate ratio; and metformin plasma levels generally >5 mcg/mL. If lactic acidosis is 
suspected or confirmed, metformin must be discontinued immediately, and the participant 
should undergo clinical evaluation and appropriate management. The Sponsor Study 
Director should be notified within 24 hours of any suspected or confirmed onset of 
lactic acidosis.  
Coadministration of nintedanib with P-glycoprotein and CYP3A4 inhibitors or inducers may 
increase or decrease nintedanib exposure, respectively (see local prescribing information). As 
PLN-74809 is a moderate inhibitor of P-gp (but not an inhibitor of CYP3A4), 
participants receiving nintedanib should be monitored for potential tolerability issues, 
including treatment-emergent elevations in liver enzymes (See Section 9). 
6.6.2 
Disallowed Medications 
Treatment with potent inhibitors or inducers of CYP3A4, 2C9 or 2C19 or, potent inhibitors 
or inducers of P-gp, BCRP or OATP1B1/1B3 transporters is prohibited. This includes 
fluconazole (a strong inhibitor of 2C19 and a moderate inhibitor of 2C9 and 3A4), which is 
disallowed.   
Treatment with digoxin, which has a narrow therapeutic window and is a substrate for P-gp, 
is not allowed since PLN-74809 is a moderate inhibitor of this transporter (IC50 9.98 µM) 
and could increase digoxin exposures.  
Use of rifampin (a potent inducer of CYP3A4) is not allowed, as it is expected to result in 
reduced PLN-74809 concentrations. 
 
Grapefruit or grapefruit-containing foods and beverage are not allowed. 
 
St. John's wort is not allowed. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 31  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Treatment with a disallowed medication, other investigational drug or investigational device 
is prohibited within 30 days or, in the case of medications, 5 half-lives (whichever is longer) 
before screening. 
6.7 
Restrictions 
6.7.1 
Prior Therapy 
Previous use of IPF SoC treatment (pirfenidone or nintedanib) is allowed for participation in 
this study.  
6.7.2 
Fluid and Food Intake  
Participants should be dosed with the study drug on an empty stomach (no food for 2 hours 
before or 2 hours after dosing). Dosing should be accompanied by approximately 240 mL 
water (1 cup). 
6.7.3 
Participant Activity Restrictions 
Smoking of any kind is not permitted within 3 months of screening and throughout the study. 
6.7.4 
Contraception  
Female Participants of Childbearing Potential 
Female participants of childbearing potential must agree to use a contraceptive method with a 
failure rate of <1% per year or remain abstinent (refrain from heterosexual intercourse, if that 
is their preferred and established lifestyle) during the treatment period and for 1 month after 
the last dose of study treatment.   
A woman is considered to be of childbearing potential if:   
• She has not reached a postmenopausal state, defined as ≥12 continuous months of 
amenorrhea with no identified cause other than menopause or 6 months of 
spontaneous amenorrhea with serum follicle-stimulating hormone [FSH] levels 
>40 mIU/mL 
• She has not undergone surgical sterilization, defined as hysterectomy, bilateral 
salpingectomy, and/or bilateral oophorectomy 
Examples of contraceptive methods with a failure rate of < 1% per year include: 
• Bilateral tubal ligation  
• Male sterilization (>3 months from Day 1 or provide a zero sperm count) 
• Hormonal contraceptives that inhibit ovulation (initiated >3 months from Day 1) 
• Hormone-releasing intrauterine devices (initiated >3 months from Day 1) 
• Copper intrauterine devices (initiated >3 months from Day 1) 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 32  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Male Participants 
Male participants, including those who are surgically sterile, must agree to use contraceptive 
measures, as defined below, or alternately to remain abstinent (refrain from heterosexual 
intercourse)   
• Male participants, with female partners of childbearing potential, must use a condom 
plus an additional contraceptive method that together result in a failure rate of < 1% 
per year or remain abstinent during the treatment period and for at least 3 months 
after the last dose of study treatment. 
• Male participants with pregnant female partners are excluded from this study. 
• Male participants whose female partners become pregnant during the study must stop 
the medication immediately as outlined in Section 8.6. 
Female and Male Participants 
Highly effective methods of birth control are defined as those with a failure rate of < 1% per 
year (adapted from Trussell, 2004; CTFG 2014). 
The reliability of sexual abstinence should be evaluated in relation to the duration of the 
clinical trial and the preferred and usual lifestyle of the participant. Periodic abstinence (e.g., 
calendar, ovulation, symptothermal, or postovulation methods) and withdrawal are not 
acceptable methods of contraception. Complete abstinence is considered a highly effective 
method when refraining from heterosexual intercourse during the entire period of risk 
associated with the study treatment.   

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 33  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
7 
STUDY PROCEDURES 
The Schedule of Events with study activities is provided in Appendix 1. 
When several assessments are required at the same time point, evaluations should be 
completed so that the PK sample is collected at the required time. It is understood that other 
assessments such as ECGs, vital signs, etc. will be performed as close to the time point as 
possible. 
7.1 
Informed Consent 
Written and dated informed consent, describing the study and all anticipated risks of 
participation must be obtained from each study participant prior to any study-related 
procedures being performed. 
7.2 
Medical History 
Medical history of the previous 5 years will be reviewed and recorded at screening. It should 
also include any relevant information or condition relevant to the purposes of this study, 
regardless of the timeframe. 
7.3 
Demographic Information 
Date of birth, sex, ethnicity, and race will be recorded at screening.  
7.4 
Physical Examination 
Complete and targeted physical examinations will be performed at the time points specified 
in the Schedule of Events (Appendix 1). Complete physical examinations include general 
appearance, head, ears, eyes, nose, throat, dentition, thyroid, chest (heart, lungs), abdomen, 
skin, neurological, extremities, back, neck, musculoskeletal, and lymph nodes. Targeted 
physical examination after screening will only be performed based on prior findings in the 
general exam, and includes head, ears, eyes, nose, throat, heart, lungs, abdomen, skin, 
musculoskeletal and lymph nodes, and any pertinent system based on any prior findings. 
Physical examinations may be performed at various unscheduled time points if deemed 
necessary by an Investigator. 
7.5 
Vital Signs 
Blood pressure and heart rate will be recorded with participants having rested for at least 
3 minutes in a supine position. Body temperature (preferably by ear) will be measured and 
peripheral capillary oxygen saturation (SpO2) will be measured using a finger pulse oximeter.  
7.6 
Electrocardiograms 
Triplicate 12‑lead ECGs will be obtained at the visits specified in the Schedule of Events 
(Appendix 1). ECG collection during the study will be performed using standardized 
equipment and centrally read. ECGs will be collected prior to a time-matched PK sample at 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 34  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
least 2 hours postdose). Additional 12‑lead ECGs may be obtained at other times if clinically 
indicated, using unscheduled visits. All ECGs should be obtained after the participant has 
rested quietly in the supine position for at least 10 minutes with the triplicate ECGs recorded 
within ~ 5 to 10 minutes. The triplicate ECGs will be averaged and the mean values per time 
point (average of the 3 assessments) used to interpret the ECG tracings. QT correction will 
utilize the Fridericia Method (Fridericia 1920). 
The Investigator (or designee) will evaluate the ECG tracings and will record 1 of the 
following interpretations on the electronic case report forms (eCRFs): normal; abnormal, not 
clinically significant; or abnormal, clinically significant. Clinically significant changes from 
baseline in ECG findings will be recorded as AEs. Refer to the ECG Manual for more 
information. 
7.7 
Clinical Laboratory Tests 
7.7.1 
Laboratory Parameters 
Participants will be in a seated or supine position during blood collection. Safety laboratory 
tests (hematology, serum chemistry and coagulation) will be collected from fasting (at least 
8 hours) participants where appropriate. Results from these safety laboratory assessments 
will be recorded in the electronic data capture (EDC) as detailed in the Schedule of Events 
(Appendix 1).including at the end of treatment or at early termination. A detailed list of 
laboratory tests is provided in Table 1. Creatinine clearance will be calculated using the 
Cockcroft-Gault equation. 
The Investigator will review the results of all laboratory tests as they become available and 
will ascertain if any laboratory value is abnormal or represents a clinically significant change 
from baseline for the individual participant. If a laboratory value is determined to be 
abnormal and to represent a clinically significant change from baseline for the participant, the 
Investigator will determine if it qualifies as an AE. If “yes,” the abnormality will be reported 
on the AE eCRF. All clinically significant laboratory abnormalities that occur during the 
study and that were not present at baseline should be followed and evaluated with additional 
tests, if necessary, until diagnosis of the underlying cause or resolution. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 35  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Table 1 
List of Laboratory Tests 
Hematology 
- Hematocrit (Hct) 
- Hemoglobin (Hgb) 
- Mean corpuscular hemoglobin (MCH) 
- Mean corpuscular hemoglobin concentration 
(MCHC) 
- Mean corpuscular volume (MCV) 
- Platelet count 
- Red blood cell (RBC) count  
- White blood cell (WBC) count with differential  
 
Coagulation 
- International normalized ratio (INR) 
 
Urinalysis 
- Appearance 
- Bilirubin 
- Color 
- Glucose 
- Ketones 
- Microscopic examination of sediment 
- Nitrite  
- Occult blood 
- pH 
- Protein 
- Specific gravity 
- Urobilinogen 
 
Other 
Serum and urine human chorionic gonadotropin 
(hCG) (females) 
 
Serum Chemistry 
- Alanine aminotransferase (ALT) 
- Albumin (ALB) 
- Alkaline phosphatase (ALP) 
- Alpha-1-acid-glucoprotein (AAG) 
- Amylase (reflex lipase if amylase ≥ 1.5 × ULN) 
- Aspartate aminotransferase (AST) 
- Bilirubin (total and direct) 
- Blood urea nitrogen (BUN) 
- Calcium (Ca) 
- Chloride (Cl) 
- Creatinine 
- Creatine kinase (CK)  
- Gamma-glutamyl transferase (GGT) 
- Glucose 
- High-sensitivity C-reactive protein (hsCRP) 
- Lactate dehydrogenase (LDH) 
- Phosphorus 
- Potassium (K) 
- Sodium (Na) 
- Total cholesterol 
- Total protein 
- Triglycerides 
- Troponins 
- Uric acid 
 
 
7.7.2 
Sample Collection, Storage, and Shipping 
Refer to the study manual for details regarding sample collection, storage, and shipping. 
7.8 
Dispensing Study Drug 
Participants will receive study drug at the timepoints indicated in the Schedule of Events 
(Appendix 1).  

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 36  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
7.9 
Pharmacokinetic Assessments 
On Day 1, total and unbound plasma samples for PLN-74809 PK analysis will be obtained 
predose and at 2, 4, and 6 hours postdose. 
At steady-state, total and unbound plasma samples for PLN-74809 PK analysis will be 
obtained predose and at least 2 hours postdose at Weeks 4 and 12, as indicated in the 
Schedule of Events (Appendix 1). Samples will be obtained and stored as detailed in the 
study manual.  
The actual collection time of each sample, as well as the dosing time, must be recorded in the 
source data and on the eCRF. If the participant discontinues the study early, a plasma sample 
for PK should be taken at the ET visit if possible. 
Aliquots of these PK samples may be used to measure nintedanib and/or pirfenidone 
concentrations in those participants who are receiving background SoC.  
If participants experience treatment-emergent elevations in liver enzymes or ECG 
abnormalities, additional PK samples will be collected at the time of repeat laboratory or 
ECG testing (See Sections 9 and 10). 
7.10 
Pharmacodynamic Assessments  
7.10.1 
PET/MRI Imaging for the Assessment of Type 1 Collagen Deposition 
All PET/MRI will be performed at the Martinos Center for Biomedical Imaging at 
Massachusetts General Hospital. PET imaging will be performed at prespecified times 
according to the Schedule of Events (Appendix 1) using the collagen-targeted tracer, 
68Ga-CBP8 as synthesized at the Martinos Center for Biomedical Imaging, and following 
predefined instructions as detailed in the Radiology Manual for the study. The radiochemical 
dose is up to 12.9 mCi per administration; but in practice, the dose averages to 5.5 mCi per 
subject. The total amount of radiation exposure from the PET/MRI is equal to a whole-body 
exposure up to 22 mSv (11 mSv per administration of 68GaCBP8). Blood samples will be 
obtained prior to each PET/MRI and will be stored for future analyses. Details for blood 
sample collection and processing are detailed in the Radiology Manual. 
7.10.2 
MRI for the Assessment of PET/MRI Relationship 
All participants will undergo dynamic contrast-enhanced MRI during each PET/MRI session. 
This will be performed using gadoterate meglumine at a predefined weight-base dose and 
injection rate, as detailed in the study’s Radiology Manual. Additional MRI sequences for 
anatomic assessment will be performed as detailed in the Radiology Manual.  
7.10.3 
Biomarkers in Urine, Plasma, and Serum 
Urine, plasma and serum samples will be obtained at predetermined times as indicated in the 
Schedule of Events (Appendix 1). These samples will be used to measure specific proteins, 
peptides, metabolites and/or mRNA transcripts that may be elevated in patients with 
inflammatory/fibrotic disease or act as PD markers that may change with inhibition of αvβ6. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 37  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
The Sponsor may also use these samples to perform exploratory investigations using 
metabolomic, transcriptomic or proteomic methods to identify putative biomarkers for use in 
future studies in participants with fibrotic diseases. Details of sample collection, storage, and 
assay will be provided in the study manual.  
A table of exploratory biomarkers of interest and evidence for their prognostic or PD value is 
presented below.  
Category 
Biomarker 
Evidence of Prognostic or Pharmacodynamic Value  
Epithelial 
Damage 
Cytokeratin 19 fragment 
(CYFRA 21-1) 
Higher levels of CYFRA 21-1 predict a worse prognosis 
among IPF patients; Change from baseline to 3 months 
predictive of mortality (Simpson 2017) 
Fibrosis 
ProC3, Pro C6 (Type III and 
type VI collagen synthesis 
neoepitopes) 
Elevated serum levels in participants with progressive 
disease compared to those with stable disease (Organ 2019) 
Periostin (POSTN) 
Prognostic for FVC in the test cohort (Effect size=-3.6, 
p<0.001) and replication cohort (Effect size=-2.5, p=0·186) 
(Neighbors 2018) 
Cartilage Oligomeric Matrix 
Protein (COMP) 
Increased in serum of IPF; correlates with declines in FVC; 
colocalizes with pSMAD3 expressing cells by IHC 
(Vuga 2013) 
Inflammation 
CCL18 
Prognostic for FVC in the test cohort (Effect size=-3.1, 
p=0·032) and replication cohort (Effect size=3.6, p=0·004) 
(Neighbors 2018) 
Exploratory 
Human Epididymis Protein 4 
(HE4) 
Elevated in IPF patient urine/plasma; significantly reduced 
in IPF patient plasma following lung transplant 
(Decaris 2019) 
 
7.11 
Pharmacogenomics  
A whole blood sample for deoxyribonucleic acid (DNA) isolation will be collected before 
dosing on Day 1 from each participant in the study. The DNA samples will be analyzed to 
evaluate drug metabolic enzyme and transporter polymorphisms that may contribute to the 
variability in PK of PLN-74809. Detailed instructions for the handling and shipping of 
samples will be provided in the study manual. 
7.12 
Exploratory Efficacy Assessments 
7.12.1 
Spirometry 
Absolute FVC volume and FVC percent of predicted will be assessed by spirometry at 
screening and at the timepoints specified in the Schedule of Events (Appendix 1). A 
historical value may be used if it has been completed within 1 month from the Baseline visit. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 38  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
FEV1 will be assessed by spirometry at screening. A historical value may be used if it has 
been completed within 1 month from the Baseline visit. 
7.12.2 
Patient-reported Outcome (PRO) 
Study participants will respond to a VAS for cough severity at the timepoints specified in the 
Schedule of Events (Appendix 1). 
7.13 
Concomitant Medication and Adverse Event Assessments 
At each study visit, participants will be asked about how they are feeling and what 
medications they are taking (have started/stopped, adjusted dose, etc.). 
7.14 
Missed Assessments 
Missed assessments will reported as such and will not be imputed. 
7.15 
Appropriateness of Measurements 
Collagen accumulation within the lungs of patients with fibrotic lung disease, particularly 
those with IPF, is the hallmark of disease progression and associated with substantial 
mortality. The changes in the PET ligand 68Ga-CBP8 correlate with disease progression and 
may be a more sensitive measure of active disease, with 68Ga-CBP8 preferentially binding to 
recently synthesized collagen over mature, organized collagen. Consistent with the 
mechanism of action of PLN-74809, changes in the PET ligand 68Ga-CBP8 will support the 
role of 68Ga-CBP8 as an important biomarker of disease activity, as well as evidence of PD 
effect and efficacy of PLN-74809 (decrease in collagen levels) in participants with IPF. 
Collection of AEs, safety labs, vital signs, physical examinations and ECG recordings are 
standard well-established parameters to assess the safety and tolerability of pharmacological 
agents.  
PK samples will be analyzed according to predefined validated analytical methods to assess 
the concentrations of PLN-74809 in plasma.  
FVC is a standard measure collected according to current ATS guidelines for the 
measurement of IPF progression. The VAS scale for the assessment of cough will follow 
recommendations from the ERS Guidelines (Morice et al, 2007).  
When available, appropriate standard guidelines will be used. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 39  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
8 
SAFETY ASSESSMENTS 
8.1 
Timing 
In this study, AEs will be collected from the time the participant signs the ICF until the 
participant's last study visit. 
8.2 
Definition of an Adverse Event  
An AE is any event, side effect, or other untoward medical occurrence that occurs in 
conjunction with the use of a study drug in humans, whether or not considered to have a 
causal relationship to this treatment. An AE can, therefore, be any unfavorable and 
unintended sign (that could include a clinically significant abnormal laboratory finding), 
symptom, or disease temporally associated with the use of a study drug, whether or not 
considered related to the study drug. Events meeting the definition of an AE include:  
• Exacerbation of a chronic or intermittent pre-existing condition including either an 
increase in frequency and/or intensity of the condition 
• New conditions detected or diagnosed after study drug administration even though it may 
have been present prior to the start of the study 
• Signs, symptoms, or the clinical sequelae of a suspected interaction 
• Signs, symptoms, or the clinical sequelae of a suspected overdose of either study drug or 
a concomitant medication (overdose per se will not be reported as an AE/ serious adverse 
event [SAE]). 
Events that do not meet the definition of an AE include: 
- 
Medical or surgical procedure (e.g., endoscopy, appendectomy); the condition that 
leads to the procedure is an AE 
- 
Situations where an untoward medical occurrence did not occur (e.g., social and/or 
convenience admission to a hospital) 
- 
Anticipated day-to-day fluctuations of pre-existing disease(s) or condition(s) present 
or detected at the start of the study that do not worsen 
 
If there is evidence of an AE through report or observation, the Investigator or designee will 
evaluate further and record the following information:  
• Time of onset and resolution 
• Severity 
• Causality/relation to study treatment 
• Action taken regarding study drug 
• Outcome 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 40  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
8.3 
Severity of an Adverse Event 
Grading the severity of AEs will use the Common Terminology Criteria for Adverse Events 
(CTCAE) grading system (Version 5.0), as described below. The clinical significance of the 
AE is determined by the Investigator. The Investigator is encouraged to consult with the 
Study Director.  
Grade 1 
Mild; asymptomatic or mild symptoms; clinical or diagnostic observations only; 
intervention not indicated 
Grade 2 
Moderate; minimal, local or noninvasive intervention indicated; limiting age-
appropriate instrumental ADL*. 
Grade 3 
Severe or medically significant but not immediately life-threatening; 
hospitalization or prolongation of hospitalization indicated; disabling; limiting 
self-care ADL** 
Grade 4 
Life-threatening consequences; urgent intervention indicated 
Grade 5 
Death related to AE 
A semi-colon indicates ‘or’ within the description of the grade. 
*Instrumental Activities of Daily Living (ADL) refer to preparing meals, shopping for groceries or clothes, 
using the telephone, managing money, etc. 
**Self-care ADL refer to bathing, dressing and undressing, feeding self, using the toilet, taking medications, 
and not bedridden. 
Common Terminology Criteria for Adverse Events (CTCAE) Version 5.0. Published: November 27, 2017 
https://ctep.cancer.gov/protocoldevelopment/electronic_applications/docs/ctcae_v5_quick_reference_8.5x11.pd
f 
 
8.4 
Causal Relationship of an Adverse Event 
The Investigator will assess the relationship between study drug and the occurrence of each 
AE. The Investigator’s assessment of the relationship of each AE to study drug will be 
recorded in the source documents and the eCRF. Alternative causes, such as medical history, 
concomitant therapy, other risk factors, and the temporal relationship of the event to the 
study drug should be considered and investigated, if appropriate. The following definitions 
are general guidelines to help assign grade of attribution. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 41  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
The relationship or association of the AE to a study drug (PLN-74809 or placebo) should be 
assessed using clinical judgment and the following considerations: 
No  
(not related): 
Evidence exists that the adverse event has an etiology other than the study 
drug. For SAEs, an alternative causality must be provided (eg, pre-existing 
condition, underlying disease, intercurrent illness, or concomitant 
medication). 
Yes 
(related): 
A temporal relationship exists between the AE onset and administration of the 
study drug that cannot be readily explained by the participant’s clinical state 
or concomitant therapies. Furthermore, the AE appears with some degree of 
certainty to be related, based on the known therapeutic and pharmacologic 
actions or AE profile of the study drug. In case of cessation or reduction of 
the dose, the AE abates or resolves and reappears upon re-challenge. 
 
The relationship to study procedures (such as venipuncture) should be assessed using the 
following considerations: 
No 
(not related): 
Evidence exists that the AE has an etiology other than the study procedure 
Yes 
(related): 
The AE occurred as a result of protocol-mandated procedures. 
 
8.5 
Outcome  
The outcome of an AE will be recorded on the AE eCRF as follows:  
• Recovered / Resolved 
• Recovering / Resolving 
• Recovered / Resolved with Sequelae 
• Not Recovered / Not Resolving 
• Fatal 
• Unknown 
 
8.6 
Pregnancy 
A pregnancy is not an AE. If a female participant or the female partner of a male study 
participant becomes pregnant while enrolled in the study following administration of study 
drug and within 30 or 90 days, respectively, after administration of the last dose of study 
drug, the Sponsor must be notified within 24 hours of the Investigator learning of the 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 42  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
pregnancy. Administration of study drug will be discontinued immediately, and the 
participant or the female partner of a male study participant will be followed through the 
outcome of the pregnancy. The Investigator is required to provide all the relevant information 
to the Sponsor using the Pregnancy Information Form to do so. 
The pregnancy will be followed through delivery. If the pregnancy results in a congenital 
anomaly/birth defects, this will be considered and reported as an SAE as per definition 
detailed in Section 8.8. 
8.7 
Clinical Laboratory Adverse Events 
Abnormal laboratory findings (eg, clinical chemistry, hematology and urinalysis) or other 
abnormal assessments (eg, ECG, vital signs) per se are not reported as AEs. However, those 
abnormal findings that are deemed clinically significant or are associated with signs and/or 
symptoms must be recorded as AEs if they meet the definition of an AE, as described in 
Section 8.2 (or recorded as an SAE if they meet the criteria of being serious, as described in 
Section 8.8). Clinically significant abnormal laboratory or other abnormal findings that are 
detected after consent or that are present at baseline and worsen after consent are included as 
AEs (and SAEs if serious). 
The Investigator should exercise his/her medical and scientific judgment in deciding whether 
an abnormal laboratory finding or other abnormal assessment is clinically significant. 
Usually, the abnormality should be associated with a clinically evident sign or symptom, or 
be likely to result in an evident sign or symptom in the near term, to be considered clinically 
significant. A clinically significant laboratory abnormality in the absence of clinical 
symptoms may jeopardize the participant and may require intervention to prevent immediate 
consequences. For example, a markedly low serum glucose concentration may not be 
accompanied by coma or convulsions, yet be of a magnitude to require glucose 
administration to prevent such sequelae. 
8.8 
Serious Adverse Events 
8.8.1 
Definition of Serious Adverse Events 
A SAE is any untoward medical occurrence that at any dose:  
• Is life-threatening 
- 
An AE is considered life-threatening if, in the opinion of either the Investigator or the 
Sponsor, its occurrence places the participant at immediate risk of death. It does not 
include an AE that, had it occurred in a more severe form, might have caused death. 
• Results in death 
• Requires inpatient hospitalization (ie, admission) or prolongation of existing 
hospitalization. Except: 
- 
An emergency room visit without hospitalization is not considered fulfilling the 
serious criteria of hospitalization. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 43  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
- 
Planned hospitalization or surgical procedures for an illness or disease which existed 
before the participant was enrolled in the clinical trial is not considered an SAE 
unless the condition deteriorated in an unexpected manner. 
• Results in persistent or significant disability/incapacity 
• Is a congenital anomaly/birth defect  
• Is an important medical event 
- 
An event that does not fulfill any of the serious criteria above, but is considered to be 
clinically significant and may jeopardize the participant, or when medical or surgical 
intervention may be required to prevent one of the outcomes listed above.  
- 
Examples of such events include, but are not limited to: laboratory abnormalities 
meeting the criteria for suspected drug induced liver injury (DILI) or QT prolongation 
that lead to permanent study drug discontinuation, allergic bronchospasm requiring 
intensive treatment at an emergency room or at home, blood dyscrasias, convulsions 
that do not result in inpatient hospitalization, or the development of drug dependency 
or drug abuse.  
8.8.2 
Recording Adverse Events and Serious Adverse Events 
All AEs and SAEs spontaneously reported by the participant and/or in response to an open 
question from study personnel or revealed by observation, physical examination or other 
diagnostic procedures will be recorded on the appropriate page of the eCRF. Any clinically 
relevant deterioration in laboratory assessments or other clinical finding is considered an AE 
and must be recorded on the appropriate pages of the eCRF. When possible, signs and 
symptoms indicating a common underlying pathology should be noted as one comprehensive 
event. 
8.8.3 
Reporting Serious Adverse Events 
In order to meet the requirements for expedited reporting of SAEs meeting specific 
requirements to applicable regulatory authorities and Institutional Review Boards (IRBs)/ 
Independent Ethics Committee (IECs)/ Research Ethics Boards (REBs), all SAEs must be 
reported to the Sponsor per the Study Manual within 24 hours from the time site personnel 
first become aware of the event by completing the SAE form and emailing it to the below:  
ctisafety@ctifacts.com 
Initial notification of an SAE by telephone must be confirmed in writing within 24 hours by 
completing the SAE form. As further information regarding the SAE becomes available, such 
follow up information should be documented and sent to ctisafety@ctifacts.com. 
All SAEs must be followed by the Investigator to resolution or medical stabilization.  
Withdrawal from the study in the event of a SAE and therapeutic measures taken shall be at 
the discretion of the Investigator. A full explanation for the discontinuation from the study 
should be made in the eCRF. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 44  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
8.8.4 
Reporting SAEs to Regulatory Authorities and IRB/IEC/REB  
The reporting of any SAEs to applicable regulatory authorities will be the responsibility of 
the Sponsor in compliance with applicable country regulations. All SAEs must be reported to 
the IRB/IEC/REB by the Investigator in accordance with their regulations. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 45  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
9 
MONITORING AND MANAGEMENT OF ELEVATED LIVER 
BIOCHEMISTRY TESTS 
Reference ranges for key liver biochemistry tests are shown in Table 2.  
Table 2 
Reference Ranges for Key Laboratory Liver Function Tests 
Parameter 
Reference Range 
Alanine aminotransferase (ALT) 
10 – 55 U/L 
Aspartate aminotransferase (AST) 
10 – 40 U/L 
Alkaline phosphatase (ALP) 
45 – 115 U/L 
Total bilirubin 
0.0 – 1.0 mg/dL 
 
Participants who experience treatment-emergent elevations in serum ALT or AST that reach 
the thresholds listed below must be managed carefully: 
• ALT or AST ≥ 8 × ULN 
• ALT or AST ≥ 5 × ULN for more than 2 weeks 
• ALT or AST ≥ 3 × ULN and (Total Bilirubin >2 × ULN or international normalized 
ratio [INR] >1.5) 
• ALT or AST ≥ 3 × ULN with liver-related symptoms including the appearance of 
fatigue, nausea, vomiting, right upper quadrant pain or tenderness, fever, rash, and/or 
eosinophilia (> 5%)  
 
Participants must return to the study site for reevaluation within 48 to 72 hours after the 
abnormal laboratory results become available for confirmatory testing serum levels of ALT, 
AST, total and direct bilirubin, and INR. A PK sample must be obtained at the same time that 
the repeat clinical laboratory samples are drawn, and the date and time of the PK draw and 
the last dose of study drug (and that of pirfenidone or nintedanib, if applicable) must be 
recorded in the eCRF.  
If prompt evaluation is not possible within 48 to 72 hours after receipt of the abnormal 
laboratory results, study drug should be interrupted immediately (date of last study 
drug dose [and that of pirfenidone or nintedanib, if applicable] must be recorded in the 
eCRF), and the participant must return to the study site as soon as possible for 
reevaluation. The Sponsor Study Director should be notified of laboratory abnormalities and 
any clinical symptoms within 48 hours of the availability of laboratory results and/or 
assessment of clinical symptoms. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 46  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Participants who experience treatment-emergent elevations in ALT or AST ≥ 2 × ULN (but 
< 3 × ULN) should be managed as follows: 
• Participants must return to the study site for reevaluation within 48 to 72 hours after the 
abnormal laboratory results become available for confirmatory testing serum levels of 
ALT, AST, total and direct bilirubin.  
• A PK sample must be obtained at the same time that the repeat clinical laboratory 
samples are drawn, and the date and time of the PK draw and the last dose of study drug 
(and that of pirfenidone or nintedanib, if applicable) must be recorded in the eCRF.  
 
In the absence of liver-related symptoms and/or elevations in total bilirubin or INR, 
participants with confirmed treatment-emergent elevations in ALT or AST ≥ 2 × ULN (but 
< 3 × ULN), may continue dosing of study drug and be monitored closely with frequent (eg, 
at least once weekly) hepatic laboratory testing and clinical assessments using unscheduled 
visits, including a thorough causality evaluation and in consultation with the Sponsor Study 
Director. 
Study drug must be permanently discontinued in the event of confirmed elevations in 
serum ALT or AST that meet the following criteria for suspected acute DILI, based on 
the Guidance for Industry on Drug-Induced Liver Injury: Premarketing Clinical Evaluation 
(FDA, 2009).  
Criteria for permanent discontinuation of study drug for confirmed ALT or AST 
elevations: 
• Confirmed ALT or AST ≥ 3× ULN with (Total Bilirubin > 2 × ULN or INR > 1.5) 
and/or, presence of liver-related symptoms, if no other etiology is suspected/confirmed 
and liver enzymes are sustained following interruption of study drug  
• Confirmed ALT or AST ≥ 5× ULN for more than 2 weeks, if no other etiology is 
suspected/confirmed and liver enzymes are sustained following interruption of study drug  
• Confirmed ALT or AST ≥ 8× ULN, if no other etiology is suspected/confirmed and liver 
enzymes are sustained following interruption of study drug  
 
All elevations in serum ALT and/or AST that are confirmed upon repeat testing AND 
that meet the criteria for suspected DILI (as listed above) must be reported to the 
Sponsor Study Director within 48 hours. The participant must permanently discontinue 
study drug immediately and continue to be followed for close monitoring and causality 
and clinical evaluation as follows: 
• Repeat liver enzyme and serum bilirubin tests at least once a week until abnormalities 
stabilize (i.e., levels are clinically comparable to baseline values or baseline grade of 
abnormality) and the participant is asymptomatic 
• Obtain a detailed history of symptoms and prior or concomitant diseases 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 47  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
• Obtain a history of concomitant drug use (including nonprescription or over-the-counter 
medications and herbal and dietary supplement preparations), alcohol use, recreational 
drug use, and special diets 
• Rule out acute viral hepatitis types A, B, C, D, and E; alcoholic hepatitis; 
hypoxic/ischemic hepatopathy; and biliary tract disease 
• Obtain immunoglobulin G1 (IgG-1), antinuclear antibody (ANA), anti-smooth muscle 
antibody (anti-SMA), anti-liver-kidney microsome type 1 (anti-LKM1), and anti-liver 
cytosolic antigen type 1 (anti-LC1) levels to be compared with baseline values, to rule 
out autoimmune hepatitis 
• Obtain a history of exposure to environmental chemical agents 
• Consider a gastroenterology or hepatology consultation, which may include a liver 
biopsy, for definite diagnosis 
 
For participants with confirmed elevations in liver enzymes (as described above) warranting 
temporary interruption of study drug but not meeting permanent drug discontinuation criteria 
as stated above, more frequent hepatic laboratory testing and clinical assessments must be 
conducted using unscheduled visits, including a thorough causality evaluation and in 
consultation with the Sponsor Study Director.  
Reinitiation of study drug can only be considered if another etiology is identified and 
confirmed and if liver abnormalities have returned to baseline values. The decision to 
restart study drug must be discussed and approved in consultation with the Sponsor 
Study Director prior to reinitiation.  
Participants who permanently discontinue study drug due to potential liver toxicity must be 
followed for close monitoring until abnormalities stabilize to baseline levels or baseline 
grade of abnormality and the participant is asymptomatic. Participants should be encouraged 
to remain in the study and completed all scheduled visits and assessments. Long-term 
follow-up information should be provided for participants who permanently discontinue drug 
due to potential liver toxicity, including information on immunosuppressive therapy and new 
liver histology. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 48  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
10 
MONITORING AND MANAGEMENT OF ECG-RELATED 
ABNORMALITIES 
The definition of a cardiac dysrhythmia characterized by a CTCAE Version 5 grading for 
electrocardiogram QT corrected interval prolonged is presented in Table 3. 
Table 3 
CTCAE Version 5 Grading for Electrocardiogram QT Corrected 
Interval Prolonged 
CTCAE Term 
Grade 1 
Grade 2 
Grade 3 
Grade 4 
Electrocardiogram 
(ECG) QT Corrected 
Interval Prolonged 
Average QTc 
450 – 480 msec 
Average QTc 
481 – 500 msec 
Average QTc 
≥ 501 msec ; or 
≥60 msec change 
from baseline 
Torsade de 
pointes; 
polymorphic 
ventricular 
tachycardia; 
signs/symptoms of 
serious arrhythmia 
 
Any participant who experiences a treatment-emergent QT interval corrected for heart rate 
(QTc) prolongation of Grade 2 or higher must return to the study site for prompt clinical 
evaluation after the abnormal ECG results become available and to repeat the safety ECG 
assessment. A PK sample must be obtained at the same visit that the repeat ECG assessment 
is performed, and the date and time of the PK draw and the last dose of study drug (and that 
of pirfenidone or nintedanib, if applicable) must be recorded in the eCRF.  
• Grade 2 QTcF interval > 480 but ≤ 500 msec; or increased > 30 to ≤ 60 msec from 
baseline value → The participant must return to the study site within 48 to 72 hours. 
• Grade 3: QTcF interval > 500 msec or increased > 60 msec from baseline value → The 
participant must return to the study site within 24 hours or, if not feasible, to a local 
clinic or hospital for immediate clinical evaluation. 
 
Clinical evaluation must include the following:  
• Ruling out comorbidities and potential risk factors (eg, congestive heart failure, 
bradyarrhythmias) 
• Evaluation of electrolyte disturbances (eg, potassium, calcium, and magnesium) 
• Review of potential concomitant medications known to prolong the QTc interval (eg, 
serotonin receptor antagonists, anti-emetics) 
 
If prompt evaluation is not feasible (as described above and based on severity of 
abnormality), study drug should be interrupted immediately (date of last study drug 
dose [and that of pirfenidone or nintedanib, if applicable] must be recorded in the 
eCRF), and the participant must return to the study site as soon as possible for 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 49  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
re-evaluation. The Sponsor Study Director should be notified within 48 hours of the 
availability of initial ECG results and/or assessment of clinical symptoms. 
Study drug must be permanently discontinued in the event of QTc prolongation 
meeting the following criteria: 
• Confirmed Grade 3 abnormality: QTcF interval > 500 msec or increased > 60 msec from 
baseline value 
• Grade 4 abnormality (does not require confirmation): torsade de pointes; polymorphic 
ventricular tachycardia; signs/symptoms of serious arrhythmia  
 
All treatment-emergent QTc abnormalities meeting the criteria for permanent 
discontinuation (as listed above) must be reported to the Sponsor Study Director within 
48 hours. The participant must permanently discontinue study drug immediately and 
continue to be followed for close monitoring and causality and clinical evaluation as 
follows: 
• Repeat ECG at least once weekly until abnormalities stabilize (ie, QTc interval is 
comparable to baseline value or baseline grade of abnormality, if applicable) and the 
participant is asymptomatic 
• Correction of any electrolyte abnormalities, if applicable 
• Obtain a detailed history of symptoms and comorbidities 
• Obtain a history of concomitant drug use (including nonprescription or over-the-counter 
medications and herbal and dietary supplement preparations) 
• Consider a cardiology consultation 
 
For participants with confirmed QTc prolongation (as described below) warranting 
temporary interruption of study drug but not meeting permanent drug discontinuation criteria, 
more frequent ECG testing and clinical assessments (at least once weekly) must be 
performed using unscheduled visits, including a thorough causality evaluation and in 
consultation with the Sponsor Study Director.  
• Confirmed Grade 2 QTcF interval >480 but ≤ 500 msec 
• Confirmed increased > 30 to ≤ 60 msec from baseline value 
 
Re-initiation of study drug can only be considered if a more likely etiology is identified and 
if ECG abnormalities have returned to baseline values. The decision to restart study drug 
must be discussed and approved in consultation with the Sponsor Study Director prior 
to re-initiation. More frequent clinical monitoring and ECG assessments (at least once 
weekly) after re-initiation of study drug, if applicable, should be performed through use of 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 50  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
unscheduled visits. If the QTc prolongation reoccurs upon re-challenge, study drug must 
be permanently discontinued. 
Any participant who experiences a QTc prolongation not confirmed upon repeat ECG 
assessment may continue or resume administration of study drug and follow the scheduled 
study visits, if clinically appropriate. More frequent clinical evaluation and ECG monitoring 
through use of unscheduled visits is allowed, if clinically warranted.  
Participants who permanently discontinue study drug due to potential QTc prolongation must 
be followed for close monitoring until abnormalities stabilize to baseline levels or baseline 
grade of abnormality and the participant is asymptomatic. Participants should be encouraged 
to remain in the study and completed all scheduled visits and assessments. Long-term 
follow-up information should be provided for participants who permanently discontinue drug 
due to confirmed QTc prolongation, including information on corrective therapy and 
cardiology consultation, if applicable. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 51  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
11 
EARLY DISCONTINUATION OF STUDY OR INDIVIDUAL 
PARTICIPANTS 
In accordance with the Declaration of Helsinki, participants have the right to withdraw from 
the study at any time for any reason. The Investigator or Sponsor may withdraw a participant 
from the study or discontinue study drug for any of the following reasons: 
• Noncompliance with protocol procedures including those relating to administration of 
study drug 
• A serious or intolerable AE occurs 
• Infection with COVID-19 that precludes safe participation in the study 
• A clinically significant change in a laboratory parameter occurs 
• Confirmed elevations in serum ALT or AST meeting criteria for suspected acute DILI 
(see Section 9) 
• Prolonged ECG QTc interval meeting criteria for permanent discontinuation (see 
Section 10)  
• Male participants whose female partners become pregnant during the study must stop the 
medication immediately 
• The Sponsor or Investigator terminates the study 
• The participant requests to be discontinued from the study 
 
If a participant is withdrawn from the study or discontinues study drug, they will undergo 
early termination assessments; refer to the Schedule of Events (Appendix 1). 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 52  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
12 
PLANNED STATISTICAL METHODS 
12.1 
General Considerations 
This is an exploratory study, with exploratory efficacy and biomarker assessments; as such, 
no statistical hypotheses are being tested. In general, data will be summarized using 
statistical summary methods; graphic presentations of data may also be prepared. A statistical 
analysis plan (SAP), prepared and agreed before final database lock, will describe the 
analytic approach and methods in more detail. 
12.2 
Determination of Sample Size 
The sample size of approximately 12 participants (8 participants receiving 160 mg 
PLN-74809 and 4 receiving placebo) is expected to provide a meaningful evaluation of 
PLN-74809 safety, tolerability and PK in the target population, and add to the data of 
approximately 21 participants planned to be evaluated at this dose level in an ongoing 
multicenter, dose ranging Phase 2a study (PLN-74809-IPF-202).  
12.3 
Analysis Populations  
Safety Population: All randomized participants who receive at least one dose of study drug 
will be included in the safety analyses. 
PK Analysis Population: All randomized participants who have sufficient PLN-74809 
concentration data for PK calculation will be included in the PK analyses.  
PD Analysis Population: All randomized participants who receive any amount of study drug 
and who have results from Baseline and from at least one post-baseline PET/MRI scan or PD 
assessment will be included in the PD analyses. 
12.4 
Demographics and Baseline Characteristics 
Data will be summarized using statistical summary methods. 
12.5 
Primary Endpoints 
12.5.1 
Primary Pharmacodynamic Endpoint 
• Quantification of type 1 collagen in the lung following 12 weeks of treatment, as assessed 
by changes from Baseline in 68Ga-CBP8 PET/MRI tracer uptake patterns. 
 
If a participant elects to withdraw from the study after the 6th week of randomization, an end 
of participation 68Ga-CBP8 PET/MRI will be offered to the participant to enhance 
appropriate data capture. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 53  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
PET/ MRI 
PET/MRI scans will be interpreted by American Board of Nuclear Medicine (ABNM)-
certified nuclear medicine physicians in an unblinded manner. Lung contours will be 
generated from baseline and post-treatment PET/MRI. Mean and maximum standardized 
uptake value (SUV) measurements of contoured lungs will be calculated using MIMS 
software, by analyzing the uptake values of 68Ga-CBP8 PET/MRI within the lung, and by 
comparing values from the baseline and post-treatment scans. Numerical and graphical 
results will be presented by dose.  
In addition, relationships between PK and type 1 collagen deposition, as well as between 
MRI and PET imaging, may be evaluated in an exploratory fashion and presented in a 
graphical manner (see Section 12.7.1). 
12.6 
Secondary Endpoints 
12.6.1 
Secondary Safety Endpoint 
• Assessment of the safety and tolerability of PLN-74809 in IPF participants 
 
Safety data from all participants who received at least one dose of study drug will be 
incorporated into the final safety analysis. Further details of the safety analyses will be 
provided in the SAP. AEs will be collected from the time the participant signs the ICF until 
the last study visit. Treatment-emergent adverse events (TEAEs) are defined as AEs that 
emerged or worsened in severity after the first administration of study drug. 
AEs will be coded using the Medical Dictionary for Regulatory Activities (MedDRA®). All 
AEs will be graded for severity per the CTCAE grading scale and listed by participant and 
summarized by treatment. 
The incidence of AEs, the incidence of TEAEs, the incidence of treatment-related AEs, and 
the severity of AEs will be summarized by system organ class, preferred term, and maximum 
severity. In cases where a participant reports multiple occurrences of the same event 
(preferred term), the greatest severity will be included in the summary. The number and 
percentage of participants with SAEs and treatment-related SAEs, and the number and 
percentage of participants who withdraw due to an AE will be tabulated by study treatment 
and dose. 
Clinical laboratory test parameters will be listed, using the CTCAE grading scale, for 
individual participants, with values outside the reference ranges flagged. The incidence of 
treatment-emergent laboratory abnormalities will be summarized by severity. Summary 
statistics will be calculated for each parameter. 
Individual ECG results will be listed for each participant. Summaries of ECGs will include 
changes from baseline for each parameter. The number and percentage of participants with 
abnormal ECGs will be summarized by treatment. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 54  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Vital sign measurements other laboratory tests, concomitant medications, medical history and 
changes in physical examinations at each time point will be listed by participant.  
Concomitant medications will be coded using the most current World Health Organization 
drug dictionary available. 
12.7 
Exploratory Endpoints 
12.7.1 
Exploratory Pharmacodynamic/Pharmacokinetic Endpoints 
• Relationship between PLN-74809 systemic exposure and PET imaging and biomarkers in 
IPF participants 
 
Pharmacokinetics 
Plasma PLN-74809 concentrations at each sampling time point will be presented in listings 
and summarized with descriptive statistics. Plasma PLN-74809-versus-time profiles (with 
plasma concentrations on both a log and linear scale) will be plotted for each participant. 
Non-compartmental analysis will be used to calculate PK parameters as appropriate. Plasma 
PK parameters will be presented in listings and summarized with descriptive statistics. The 
data will also be presented graphically. 
Further details of the analyses will be provided in the SAP to be prepared and agreed prior to 
final ‘database lock’ at the end of the study. The PK analysis plan and report may be 
prepared separately from the SAP as appropriate. 
PET/MRI 
Relationships between PK and type 1 collagen deposition, as well as between MRI and PET 
imaging, may be evaluated in an exploratory fashion and presented in a graphical manner. 
The analysis of PET/MRI imaging is described in Section 12.5.1. 
Pharmacodynamics: Biomarkers 
Urine, plasma, and serum samples will be analyzed for biomarkers (presence or actual 
concentration). These samples will be used to determine the levels of these markers in 
participants, the relationship between these markers, and the level of PET tracer uptake 
(type 1 collagen deposition) in the lung. Results will be presented in listings and summarized 
with descriptive statistics and in graphical form. 
12.7.2 
Exploratory Efficacy Endpoints 
12.7.2.1 
Forced Vital Capacity (FVC) 
• Absolute FVC volume and FVC as percent of predicted as assessed by spirometry 
Percent of predicted FVC and volume (mL) will be assessed using the standard spirometry 
procedure at the Chest Clinic at Massachusetts General Hospital and presented as absolute 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 55  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
values and as percent of predicted values. Baseline FVC will be the average of the screening 
and Day 1 determinations. End-of-study FVC will be the average of Week 12 and Week 14 
determinations. 
12.7.2.2 
Patient-reported Outcome (PRO) 
• Patient-reported outcome (PRO): a VAS for cough severity 
A cough VAS will be completed at the timepoints specified in the Schedule of Events 
(Appendix 1). 
12.8 
Other Assessments or Analyses 
Unbound concentrations of PLN-74809 will be determined in plasma samples. Exploratory 
metabolite evaluation may be performed in plasma samples. 
12.9 
Interim Analysis 
Not applicable  

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 56  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
13 
QUALITY CONTROL AND ASSURANCE 
During the study, the Sponsor and/or representatives of the Sponsor may visit the site to 
conduct an audit of the study. The purpose of this visit will be to determine the Investigator’s 
adherence to the protocol, applicable regulations, and the Sponsor procedures, in addition to 
assessing the accuracy of the study data. Prior to initiating this audit, the Investigator will be 
contacted by the Sponsor to arrange a convenient time for this visit. The Investigator and 
staff are expected to cooperate with the auditors and allow access to all participant records 
supporting the eCRFs and other study-related documents. 
At some point during the development program for the study drug, a regulatory authority 
may visit the Investigator to conduct an inspection of the study and the site. The Investigator 
and staff are expected to cooperate with the inspectors and allow access to all source 
documents supporting the eCRFs and other study related documents. The Investigator must 
immediately notify the Sponsor when contacted by any regulatory authority for purposes of 
conducting an inspection. 
 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 57  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
14 
ADMINISTRATIVE CONSIDERATIONS 
14.1 
Institutional Review Board, Independent Ethics Committee or Research 
Ethics Board Approval 
The Investigator must inform and obtain approval from the IRB/IEC/REB for the conduct of 
the study at named sites, for the protocol, the participant ICF, and any other written 
information that will be provided to the participants and any advertisements that will be 
used. Written approval must be obtained prior to recruitment of participants into the study 
and shipment of investigational agent.  
Proposed amendments to the protocol and aforementioned documents must be discussed 
between the Sponsor and contract research organization (CRO), and then submitted to 
the IRB/IEC/REB for approval as well as submitted to regulatory authorities for approval 
prior to implementation. Amendments may be implemented only after a copy of 
the local IRB/IEC/REB approval letter has been transmitted to the Sponsor. Amendments 
that are intended to eliminate an apparent immediate hazard to participants may be 
implemented prior to receiving Sponsor or IRB/IEC/REB approval. However, in this 
case, approval must be obtained as soon as possible after implementation.  
The Investigator is responsible for reporting protocol deviations to the IRB/IEC/REB as 
required by local requirements. The Investigator will be responsible for ensuring that an 
annual update is sent to the IRB/IEC/REB to facilitate their continuing review of the trial (if 
needed) and that the IRB/IEC/REB is informed about the end of the study. Copies of the 
update, subsequent approvals and final letter must be sent to the Sponsor.  
14.2 
Ethical Conduct of the Study 
The study will be carried out in accordance with the current version of the Declaration of 
Helsinki, concerning medical research in humans. The study will be conducted in adherence 
to the study protocol and Good Clinical Practice (GCP), as defined in Title 21 of the US 
Code of Federal Regulations Parts 50, 54 56, 312 and Part 11 as well as International Council 
on Harmonisation (ICH) E6: Guideline for Good Clinical Practice (ICH GCP) consolidated 
guidelines (E6) and applicable regulatory requirements. 
14.3 
Participant Information and Consent 
It is the Investigator’s responsibility to obtain written informed consent from the 
participant after adequate explanation of the objectives, methods, anticipated benefits, and 
potential hazards of the study and before any study procedures are commenced.  
The participant should be given a copy of the IRB/IEC/REB-approved ICF in his/her native 
language. The informed consent process should be recorded in the source 
documentation. The original copy of the signed and dated ICF must be retained in the 
institution’s records and be available for inspection by representatives of the Sponsor, or 
representatives from regulatory agencies. The participant will be given a copy of the signed 
ICF. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 58  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Participants unable to sign the ICF may participate in the study if a legal representative or 
witness provides the consent (in accordance with the procedures of ICH-GCP and local 
regulations) and the participant confirms his/her interest in study participation.  
The participant will be informed that he/she can freely withdraw consent and stop 
participation in the study at any time with no prejudice to further treatment. It is 
the participant’s responsibility to communicate this decision to the Investigator.  
14.4 
Participant Confidentiality 
The Investigator must ensure that the participant’s privacy is maintained. On the 
CRF and other documents submitted to the Sponsor, participants will be identified by 
a participant study number only. Documents that are not submitted to the Sponsor 
(eg, signed ICF) should be kept in a strictly confidential file by the Investigator.  
The Investigator shall permit authorized representatives of the Sponsor, regulatory 
agencies, and IRBs/IECs/REBs to review the portion of the participant’s medical record that 
is directly related to the study. As part of the required content of informed 
consent, the participant must be informed that his/her records will be reviewed in this 
manner. 
Applicable data privacy laws and regulations must be adhered to. The Investigator and the 
Sponsor are responsible for ensuring that sensitive information is handled in accordance with 
local requirements (eg, Health Insurance Portability and Accountability Act [HIPAA], 
Personnel Information Protection and Electronic Documents Act [PIPEDA], General Data 
Protection Regulation [GDPR]). Appropriate consent and authorizations for use and 
disclosure and/or transfer (if applicable) of protected information must be obtained. 
14.5 
Study Monitoring 
The Investigator must allow the Study Monitors to periodically review, at mutually 
convenient times, during the study and after the study has been completed, all eCRFs and 
office, hospital, and laboratory records supporting the participation of each participant in the 
study. The eCRFs and other documentation supporting the study must be kept up to date by 
the Investigator and the research staff at the investigative site. These study materials must be 
available for review by the Study Monitor, and/or other qualified representatives of the 
Sponsor, at each monitoring visit. 
It is the monitor’s responsibility to inspect the CRFs at regular intervals throughout the trial 
to verify adherence to the protocol, the completeness, accuracy and consistency of the 
data, and adherence to GCP guidelines.  
The Investigator agrees to cooperate with the monitor to ensure that any problems detected 
during the course of these monitoring visits are resolved. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 59  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
14.6 
Case Report Forms and Study Records 
The investigative site will use eCRFs to record all the protocol-specified data for each 
participant enrolled in this study. Entries made in the eCRF must be verifiable against source 
documents. Data reported in the eCRF that are derived from source documents should be 
consistent with the source documents or the discrepancies should be explained.  
The Investigator will be responsible for reviewing all data and eCRF entries and will sign 
and date the designated pages in each participant’s eCRF, verifying that the information is 
accurate. 
14.7 
Adjudication Committee 
Potential acute exacerbations, respiratory-related hospitalizations, and/or respiratory-related 
deaths will be reviewed by an adjudication committee.  
14.8 
Retention of Data 
The Investigator must ensure that all records pertaining to the conduct of the clinical study, 
ICFs, drug accountability records, source documents, and other study documentation are 
adequately maintained for a period of 2 years after the last approval of a marketing 
application in an ICH region and until there are no pending or contemplated marketing 
applications in an ICH region or at least 2 years have elapsed since the formal 
discontinuation of clinical development of the study drug.  
The Investigator must not destroy any records associated with the study without receiving 
approval from the Sponsor. The Investigator must notify the Sponsor in the event of 
accidental loss or destruction of any study records.  
Whenever possible, an original recording of an observation must be retained as the source 
document. However, a photocopy of a record is acceptable provided it is legible and is a 
verified copy of the original document.  
All eCRF data entered by the site (including audit trail), as well as computer hardware and 
software (for accessing the data), will be maintained or made available at the site in 
compliance with applicable record retention regulations. The CRO will retain the original 
eCRF data and audit trail. 
14.9 
Financial Disclosure 
Financial Disclosure statements will be handled in a separate agreement apart from the 
protocol, kept on file, and submitted as applicable with any subsequent license application.  
14.10 
Publication and Disclosure Policy 
The data generated in this clinical study are the exclusive property of the Sponsor and are 
confidential. Any publication of the results of this study must be authorized by the Sponsor. 
The Sponsor will have the opportunity to review any publications that arise from the 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 60  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Investigators before submission for publication. Any such review and approval of 
publications related to the study shall be made pursuant to the process agreed between the 
parties in the site’s clinical trial agreement with Sponsor. Authorship on any publication of 
the results from this study will be based on contributions to study design, data acquisition and 
analysis, and interpretation of results.  

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 61  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
15 
REFERENCE LIST 
CTFG. Recommendations related to contraception and pregnancy testing in clinical trials. 
2014. 
Decaris M, Rexhepaj M, et al. Urine Proteomics Identifies Novel Biomarkers of IPF Disease 
Progression and Resolution. Am J Respir Crit Care Med. 2019; 199:A1238. 
FDA. Guidance for Industry Drug-Induced Liver Injury: Premarketing Clinical Evaluation. 
July 2009. 
Fridericia LS. The duration of systole in an electrocardiogram in normal humans and in 
patients with heart disease. Acta Med Scand. 1920;53:469-6. 
Horan GS, Wood S, Ona V, et al. Partial inhibition of integrin alpha(v)beta6 prevents 
pulmonary fibrosis without exacerbating inflammation. Am J Respir Crit Care Med. 
2008;177:56-65. 
Kreuter M, Bonella F, Wijsenbeek M, et al. Pharmacological treatment of idiopathic 
pulmonary fibrosis: Current approaches, unsolved issues, and future perspectives. Biomed 
Res Int. 2015;2015:329481. 
Lederer DJ, Martinez FJ. Idiopathic pulmonary fibrosis. N Engl J Med. 2018;378:1811-1823. 
Moeller A, Ask K, Warburton D, et al. The bleomycin animal model: a useful tool to 
investigate treatment options for idiopathic pulmonary fibrosis? Int J Biochem Cell Biol. 
2008;40:362-382. 
Montesi SB, Izquierdo-Garcia D, Désogère P, et al. Type I collagen-targeted positron 
emission tomography imaging in idiopathic pulmonary fibrosis: first-in-human studies. Am J 
Respir Crit Care Med. 2019;200:258-261. 
Morice AH, Fontana GA, Belvisi MG, et al. ERS guidelines on the assessment of cough. Eur 
Respir J. 2007;29:1256-1276. 
Neighbors M, Cabanski CR, et al. Prognostic and predictive biomarkers for patients with 
idiopathic pulmonary fibrosis treated with Pirfenidone: post-hoc assessment of the 
CAPACITY and ASCEND trials. Lancet Respir Med. 2018 Aug; 6(8): 615-626.  
Organ LA, Duggan AR, et al. Biomarkers of collagen synthesis predict progression in the 
PROFILE idiopathic pulmonary fibrosis cohort. Respir Res. 2019; 20:148. 
Raghu G, Remy-Jardin M, et al. Diagnosis of Pulmonary Fibrosis. American Journal of 
Respiratory and Critical Care Medicine. 2018; 198(5): e44-e68. 
Simpson JK, Maher TM, et al. Cyfra-21-1 As A Biomarker With Prognostic Potential In 
Idiopathic Pulmonary Fibrosis: An Analysis Of The Profile Cohort. AM J Respir Crit Care 
Med. 2017; 195:A6791. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 62  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
Trussell, J. Contraceptive failure in the United States. Contraception 2004; 70:89-96. 
Vuga LJ, Milosevic J, et al. Cartilage oligomeric matrix protein in idiopathic pulmonary 
fibrosis. PLoS One. 2013 Dec 20; 8(12):e83120. 
Wilson KC, Raghu G. The 2015 guidelines for idiopathic pulmonary fibrosis: an important 
chapter in the evolution of the management of patients with IPF. Eur Respir J. 
2015;46:883-886.  

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 63  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
APPENDIX 1 
SCHEDULE OF EVENTS 
 
Screening 
 
Treatment 
EoS / ET 
Visit 1 
Visit 2 
Visit 3 
Visit 4 
Visit 5 
Visit 6 
Visit 7a 
Visit 8a 
Visit 9 
Day -28 
to Day -1 
Pre-
Baseline 
Day -7 to 
Day -1 
Baseline 
Day 1 
Week 2 
Day 14 
(±2 days) 
Week 4 
Day 28 
(±2 days) 
Week 8 
Day 56 
(±3 days) 
Day 84 
(-7days) 
Week 12 
Day 84 
(±3 days) 
Week 14  
Day 98  
(±3 days) 
Informed consent 
X 
 
 
 
 
 
 
 
 
Medical history 
X 
 
 
 
 
 
 
 
 
Demographics (age, sex, race) 
X 
 
 
 
 
 
 
 
 
Serum pregnancy test 
X 
 
 
 
 
 
 
 
 
Check inclusion and exclusion criteria 
X 
 
X 
 
 
 
 
 
 
Complete physical examination (including 
height and weight) 
X 
 
 
 
 
 
 
 
 
Targeted physical examination  
 
 
X 
X 
X 
X 
 
X 
X 
Randomization 
 
 
X 
 
 
 
 
 
 
FVC b,c 
X 
 
X 
 
X 
X 
 
X 
X 
FEV1c 
X 
 
 
 
 
 
 
 
 
DLco 
X 
 
 
 
 
 
 
 
 
Cough VAS  
X 
 
X 
X 
X 
X 
 
X 
X 
Vital signs (post 3 minutes, supine; approx 
2 hours post dose and around the time of 
the ECG) 
X 
 
X 
X 
X 
X 
 
X 
X 
Triplicate 12-lead  ECG (post 10 minutes, 
supine; at least 2 hours post dose and prior 
to the PK sample)d,e 
X 
 
X 
X 
X 
X 
 
X 
X 
Hematology (post 8-hour fast) 
X 
 
X 
X 
X 
X 
 
X 
X 
Clinical chemistry (post 8-hour fast)f 
X 
 
X 
X 
X 
X 
 
X 
X 
Coagulation (post 8-hour fast) 
X 
 
X 
X 
X 
X 
 
X 
X 
PET/MRI scan 
 
X 
 
 
 
 
X 
 
Pharmacokinetic sample plasma g 
 
 
X 
 
X 
 
 
X 
Xe,f,,h 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 64  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
 
Screening 
 
Treatment 
EoS / ET 
Visit 1 
Visit 2 
Visit 3 
Visit 4 
Visit 5 
Visit 6 
Visit 7a 
Visit 8a 
Visit 9 
Day -28 
to Day -1 
Pre-
Baseline 
Day -7 to 
Day -1 
Baseline 
Day 1 
Week 2 
Day 14 
(±2 days) 
Week 4 
Day 28 
(±2 days) 
Week 8 
Day 56 
(±3 days) 
Day 84 
(-7days) 
Week 12 
Day 84 
(±3 days) 
Week 14  
Day 98  
(±3 days) 
Pharmacokinetic nintedanib/pirfenidone 
sample plasma x 2 (predose and at least 
2 hours post dose to PLN-74809)i 
 
 
X 
 
X 
 
 
X 
Xe,f,h 
Pharmacogenomic sample  
 
 
X 
 
 
 
 
 
 
Plasma biomarker samples  
 
 
X 
 
X 
  
 
X 
  
Serum biomarker samples  
 
 
X 
 
X 
  
 
X 
  
Urine biomarker samples  
 
 
X 
 
X 
  
 
X 
  
Urine pregnancy test (positive tests will be 
confirmed with a serum test) 
  
 
X 
 
X 
X 
 
X 
X 
Urinalysis (dipstick, followed up by micro 
if abnormal) 
X 
 
X 
  
X 
X 
 
 
X 
Adverse events  
 
 
Concomitant medications 
 
 
 
Study drug administration (empty stomach: 
2 hours predose and 2 hours postdose)j 
 
 
 
 
Study drug dispensing 
 
 
X 
  
X 
X 
 
 
 
Study drug accountability 
 
 
 
  
X 
X 
 
X 
X 
DLCO = diffusing capacity for carbon monoxide; ECG = electrocardiogram; EoS = end of study; ET = early termination; FEV1 = forced expiratory volume 
during the first seconds of the forced breath; FVC = forced vital capacity; MRI = magnetic resonance imaging; PET = positron emission tomography; 
PK = pharmacokinetic; VAS = visual analog scale 
a 
Visits 7 and 8 may be combined. 
b 
Baseline FVC to be obtained both during screening and on Day 1.  
c 
A historical value may be used if it has been completed within 1 month from the Baseline visit. 
d 
When time points for ECGs, vital sign assessment, and blood draws coincide, procedures should be carried out with blood draws last. ECGs should be 
collected postdose and close to the time of PK sample collection with the triplicate ECGs recorded within ~ 5 to 10 minutes. The triplicate ECGs will be 
averaged, and the mean values per time point (average of the 3 assessments) used to interpret the ECG tracings.   
e 
ECG abnormality, then PK sample will be collected. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 65  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
 
Screening 
 
Treatment 
EoS / ET 
Visit 1 
Visit 2 
Visit 3 
Visit 4 
Visit 5 
Visit 6 
Visit 7a 
Visit 8a 
Visit 9 
Day -28 
to Day -1 
Pre-
Baseline 
Day -7 to 
Day -1 
Baseline 
Day 1 
Week 2 
Day 14 
(±2 days) 
Week 4 
Day 28 
(±2 days) 
Week 8 
Day 56 
(±3 days) 
Day 84 
(-7days) 
Week 12 
Day 84 
(±3 days) 
Week 14  
Day 98  
(±3 days) 
f 
Liver function test abnormality, then PK sample will be collected. 
g 
Total and unbound PLN-74809 levels will be measured at the following timepoints:  
Day 1: predose and 2, 4, and 6 hours postdose 
Weeks 4 and 12: predose and at least 2 hours postdose 
Actual PK sample collection time and dosing time will be recorded.  
h 
If the participant discontinues the study early, a plasma sample for PK should be taken at the ET Visit if possible.   
i 
For participants receiving nintedanib/pirfenidone only; timed relative to PLN-74809 dosing.  
j 
Participants should be instructed to take study drug in the clinic on Visits 3, 5 and 8, and at the ET visit if applicable. 

Protocol PLN-74809-IPF-205, Amendment 1, 4 October 2021 
Page 67  
 
Proprietary and Confidential  
Pliant Therapeutics, Inc. 
APPENDIX 3 
INVESTIGATOR’S SIGNATURE 
 
Study Title: 
A Phase 2a, randomized, double-blind, placebo-controlled evaluation of 
PLN-74809 on type 1 collagen deposition using 68Ga-CBP8 PET/MRI 
imaging in participants with idiopathic pulmonary fibrosis (IPF) 
Study Number: 
PLN-74809-IPF-205 
Version 
Amendment 1 
Final Date: 
4 October 2021 
I have read the protocol described above. I agree to comply with all applicable regulations, 
Good Clinical Practices, and to conduct the study as described in the protocol.  
 
 
 
 
Signed: 
 
 
Date:  
 
 
 
Name: 
 
 
 
 
Affiliation: 
 
 
 
Site Number: