AGAVE-201, A Phase 2, Open-label, Randomized, Multicenter Study to Evaluate the Efficacy, Safety and Tolerability of Axatilimab at 3 Different Doses in Patients With Recurrent or Refractory Active Chronic Graft Versus Host Disease Who Have Received at Least 2 Lines of Systemic Therapy
Phase: PHASE2
Conditions: Chronic Graft-versus-host-disease
Sponsor: Syndax Pharmaceuticals

Product: Axatilimab
05 April 2023 
Protocol Number: SNDX-6352-0504 Amendment 4.0 GLOBAL 
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SYNDAX PHARMACEUTICALS
CLINICAL STUDY PROTOCOL 
Protocol Title:
AGAVE-201, A Phase 2, Open-label, Randomized, Multicenter 
Study to Evaluate the Efficacy, Safety and Tolerability of 
Axatilimab at 3 Different Doses in Patients with Recurrent or 
Refractory Active Chronic Graft Versus Host Disease who have 
Received at least 2 Lines of Systemic Therapy 
Protocol Number: 
SNDX-6352-0504 
Protocol Amendment 
4.0 GLOBAL 
Study Intervention: 
Axatilimab (SNDX-6352) 
Study Phase: 
Phase 2 
Sponsor Name: 
Syndax Pharmaceuticals, Inc. 
Legal Registered 
Address: 
35 Gatehouse Drive 
Building D, Floor 3 
Waltham, MA 02451 
Regulatory Agency 
Identifier Number(s):
IND: 139,019 
Protocol Date:
Version 5.0, 05 April 2023 GLOBAL
Confidentiality Notice
This document contains confidential information of Syndax Pharmaceuticals, Inc., the contents 
of which must not be disclosed to anyone other than the study staff and members of the 
respective Institutional Review Board/Ethics Committee.
The information in this document cannot be used for any purpose other than the evaluation or 
conduct of the clinical investigation without the prior written consent of Syndax 
Pharmaceuticals, Inc.
NCT: NCT04710576

Product: Axatilimab
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Protocol Number: SNDX-6352-0504 Amendment 4.0 GLOBAL 
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SPONSOR SIGNATORY
 
 
Date
 
 
 

Product: Axatilimab
05 April 2023
Protocol Number: SNDX-6352-0504 Amendment 4.0 GLOBAL
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INVESTIGATOR’S AGREEMENT
I have read the attached protocol (SNDX-6352-0504) entitled “AGAVE-201, A Phase 2, 
Open-label, Randomized, Multicenter Study to Evaluate the Efficacy, Safety and Tolerability of 
Axatilimab at 3 Different Doses in Patients with Recurrent or Refractory Active Chronic Graft 
Versus Host Disease who have Received at least 2 Lines of Systemic Therapy,” dated 05 April 
2023 version 5.0 GLOBAL, and agree to abide by all provisions set forth therein. 
I agree to comply with the International Council for Harmonisation Tripartite E6 Guideline on 
Good Clinical Practice applicable regulations of the Food and Drug Administration and other 
applicable regulations. 
I agree to ensure that Financial Disclosure Statements will be completed by: 
 me 
 my sub-investigators 
at the start of the study, at study completion, and for up to 1 year after the study is completed, if 
there are changes that affect my financial disclosure status. 
I agree to ensure that the confidential information contained in this document will not be used for 
any purpose other than the evaluation or conduct of the clinical investigation without the prior 
written consent of Syndax. 
 
 
 
 
Signature 
 
 
 
Name of Principal Investigator 
 
Date 
 
 

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Protocol Amendment Summary of Changes Table
DOCUMENT HISTORY
Document
Date
Protocol V5.0, Amendment 4.0 (GLOBAL)
05 April 2023 
Protocol V4.0, Amendment 3.0 (GLOBAL)
24 May 2022
Protocol V3.0, Amendment 2.0 (GLOBAL)
17 December 2020 
Protocol V2.0, Amendment 1.0 
23 November 2020
Original Protocol V1.0  
17 September 2020 
Amendment: Amendment 3.0 (Version 4.0) dated 24 May 2022 has been updated to 
Amendment 4.0 (Version 5.0) GLOBAL dated 05 April 2023.
Overall Rationale for the Amendment: The reasons to amend Protocol SNDX-6352-0504, 
from Protocol Amendment 3.0 (GLOBAL) to Protocol Amendment 4.0 (GLOBAL), are detailed 
below. Minor editorial changes, including changes for consistency, for example, to the list of 
abbreviations, have not been listed here. For full details, please refer to the red-line version of the 
protocol. 
 
Amendment 4.0 Summary of Changes 
Section 
Description of Change
Rationale 
Section 1.1: Overall 
Design;  
And
Section 4.1: Overall 
Study Design 
Added additional description of analysis plan for 
futility, interim analysis (IA) #1 and IA #2, and safety 
assessment to explain considerations for Independent 
Data Monitoring Committee (IDMC) review.  
 
Details on the final efficacy and safety analyses were 
added. 
Based on IDMC recommendations and 
subsequent advice from the US Food and 
Drug Agency regarding dose, updates were 
incorporated into the protocol.  
 
Originally IA #2 was designed as a second 
futility analysis of the Stage 1 patients in 
each cohort after a longer treatment interval. 
However, given the fact that the study is 
fully enrolled, this analysis would be too 
limited to accurately assess the benefit/risk of 
proceeding with the protocol at the time of 
IA #2.
Section 1.1: Dosing 
Arms and Duration 
of Treatment;  
And
Section 4.4: End of 
Study Definition
Table revised to include guidance on patients who 
derive benefit after 2 years and to include Overall 
Survival follow-up period and End of Study.  
To further clarify Overall Survival stage of 
the study.
Section 1.3: 
Schedule of 
Activities (SoA) 
Table revised to add SoA for Overall Survival follow-
up and Cycles 25+. Abbreviations and footnotes were 
also updated to reflect changes in the table.  
Additional visits were included to 
accommodate patients who may continue to 
receive axatilimab if deriving benefit per the 
Investigator and Syndax post 2 years of 
treatment. 
Section 2.3: Benefit 
and Risk Analysis
Last sentence of Paragraph 4 was modified to, “The 
study design aims to provide patients with maximal 
benefit from axatilimab and reduced unnecessary risk, 
by monitoring all potential risks, and incorporating 
early stopping rules for futility and safety,” which 
removed mention of intrapatient dose escalation.
Based on IDMC recommendations and 
subsequent advice from the US Food and 
Drug Agency regarding dose, updates were 
incorporated into the protocol.  

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Amendment 4.0 Summary of Changes
Section 
Description of Change
Rationale 
Section 3: 
Objectives and 
Endpoints 
and 
Section 9.4.1 
Efficacy Analysis
Updated Key Secondary Endpoint:
 
Proportion of patients with a >5-point clinically 
significant improvement in modified Lee Symptom 
Scale score (mLSS). 
Based on advice from the US Food and Drug 
Agency. 
Section 3: 
Objectives and 
Endpoints 
and
Section 9.4.1 
Efficacy Analysis
Added an Exploratory Efficacy Endpoint:
Duration of improvement of mLSS for patients with 
7 point improvement. 
Based on advice from the US Food and Drug 
Agency.
Section 6.2: 
Intrapatient Dose 
Escalation
Revised to read: “Intrapatient dose escalation is not 
permitted. Dose adjustment(s) related to change in 
dosing schedule (Section 6.3.) are not considered dose 
escalations as the dose intensity remains unchanged.” 
Based on IDMC recommendations and 
subsequent advice from the US Food and 
Drug Agency regarding dose, updates were 
incorporated into the protocol.  
Section 6.2.1: Dose 
Changes Following 
IDMC 
Recommendations
Section revised to provide additional guidance on 
changes to dosing following IDMC recommendations 
and regulatory agency interactions. Main changes 
included: patients randomized to 3 mg/kg Q4W must 
reduce dose to 0.6 mg/kg Q4W; patients randomized 
at 1 mg/kg Q2W may continue at their current dose, 
or transition to 0.3 mg/kg Q2W; patients randomized 
at 0.3 mg/kg Q2W may continue at their current dose; 
and patients who have had their dosing schedule 
adjusted per Section 6.3 must reduce their dose to 0.6 
mg/kg Q4W, if they continue treatment on a Q4W 
schedule, or revert to the Q2W schedule at a dose 
used immediately prior to schedule adjustment.   
Based on IDMC recommendations and 
subsequent advice from the US Food and 
Drug Agency regarding dose, updates were 
incorporated into the protocol.  
Section 6.3: 
Changes to Dosing 
Schedule 
Section and all subsections revised to note that the 
highest dose available after any change would be 0.6 
mg/kg Q4W. 
Based on IDMC recommendations and 
subsequent advice from the US Food and 
Drug Agency regarding dose, updates were 
incorporated into the protocol.  
Section 6.7: 
Stopping Rules and 
Dose Modifications
Table 4 and its footnotes were revised to reflect new 
dose levels after 11 November 2022 of 0.6 mg/kg IV 
Q4W and 0.3 mg/kg IV Q2W.
Based on IDMC recommendations and 
subsequent advice from the US Food and 
Drug Agency regarding dose, updates were 
incorporated into the protocol. 
Section 6.7.2: 
Discontinuation of 
Study Treatment for 
Lack of Efficacy 
Definition of unequivocal progression of chronic 
graft-versus-host disease (cGVHD) added as 
“initiation of new systemic therapy for cGVHD; 
increase in corticosteroid and/or CNI/mTOR inhibitor 
dose beyond those allowed by protocol.” 
To clarify definition of unequivocal 
progression of cGVHD. 
Section 8.3.1: Time 
Period and 
Frequency for 
Collecting AE and 
SAE Information
Reporting timelines to the Sponsor were added for the 
adverse events of special interest (AESIs) of infusion-
related reactions (IRRs) and infections.  
24-hour reporting window for nonserious 
infections has been removed because of 
clinical experience on the axatilimab 
protocols to date. Infectious AESIs are 
entered regularly in the EDC and monitored 
in safety reviews. 
Section 9.2: Sample 
Size Determination 
Details on the final efficacy and safety analyses were 
added.
Based on actual study conduct and observed 
over-enrollment. 
Section 9.4.5: 
Interim Analysis 
Table 12 (Toxicity Stopping Boundaries) revised to 
specify stopping boundaries for IA #1. Section 
revised to include details on the analysis plan for IA 
#1, IA #2, and Final Analysis. Additions included 
Based on IDMC recommendations and 
subsequent advice from the US Food and 
Drug Agency regarding dose, updates were 
incorporated into the protocol.  
 

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Amendment 4.0 Summary of Changes
Section 
Description of Change
Rationale 
those on the futility assessments, overall evaluation of 
clinical data, and safety assessment. 
Originally IA #2 was designed as a second 
futility analysis of the Stage 1 patients in 
each cohort after a longer treatment interval. 
However, given the pace of enrollment, this 
analysis would be too limited to accurately 
assess the benefit/risk of proceeding with the 
protocol.
Section 10.3.6: 
Reporting of SAEs 
and AESI
Text clarifying type of AESI added reading: 
“infusion-related reactions, including hypersensitivity 
reactions.”
To provide clarity on why infectious AESIs 
are not being reported in an expedited 
fashion.
Section 11: 
References 
Missing references added.
Add additional references 

Product: Axatilimab
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TABLE OF CONTENTS
CLINICAL STUDY PROTOCOL ..................................................................................................1
INVESTIGATOR’S AGREEMENT...............................................................................................3
Protocol Amendment Summary of Changes Table .........................................................................4
1.
PROTOCOL SUMMARY..........................................................................................13
1.1.
Synopsis......................................................................................................................13
1.2.
Study Schema .............................................................................................................20
1.3.
Schedule of Activities (SoA) ......................................................................................21
2.
INTRODUCTION......................................................................................................26
2.1.
Study Rationale and Hypothesis.................................................................................26
2.2.
Background .................................................................................................................27
2.2.1. 
Clinical Experience with Axatilimab in Patients with cGVHD .................................28
2.3.
Benefit and Risk Analysis ..........................................................................................30
3.
OBJECTIVES AND ENDPOINTS ............................................................................31
4.
STUDY DESIGN .......................................................................................................34
4.1.
Overall Study Design..................................................................................................34
4.2.
Dose Justification........................................................................................................35
4.3.
Rationale for Study Design.........................................................................................36
4.4.
End of Study Definition ..............................................................................................37
5.
STUDY POPULATION.............................................................................................38
5.1.
Inclusion Criteria ........................................................................................................38
5.2.
Exclusion Criteria .......................................................................................................40
6.
STUDY INTERVENTION ........................................................................................42
6.1.
Study Intervention(s) Administered ...........................................................................42
6.2.
Intrapatient Dose Escalation.......................................................................................42
6.3.
Changes to Dosing Schedule ......................................................................................43
6.3.1. 
Patients Enrolled into the 1 mg/kg IV Q2W Dose Schedule ......................................43
6.3.2. 
Patients Enrolled into the 0.3 mg/kg IV Q2W Dose Schedule ...................................43
6.3.3. 
Patients Who Have Escalated to the 1 mg/kg IV Q2W Dose Schedule from 
0.3 mg/kg Q2W ..........................................................................................................44
6.3.4. 
Patients Who Have Previously Dose Reduced for Reasons of Toxicity ....................44
6.4.
Randomization to Axatilimab Dose Level .................................................................44

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6.5.
Preparation/Handling/Storage/Accountability ............................................................44
6.6.
Study Intervention Compliance..................................................................................45
6.7.
Stopping Rules and Dose Modifications ....................................................................45
6.7.1. 
Guidelines for Toxicity Management .........................................................................47
6.7.2. 
Discontinuation of Study Treatment for Lack of Efficacy .........................................50
6.8.
Rescue Medications and Supportive Care..................................................................51
6.9.
Concomitant Medication ............................................................................................51
6.9.1.
Corticosteroids, CNI and mTOR inhibitors................................................................51
6.9.2. 
Prohibited Medications ...............................................................................................52
7.
DISCONTINUATION OF STUDY DRUG AND PATIENT 
DISCONTINUATION/WITHDRAWAL ..................................................................54
7.1.
Discontinuation of Study Drug...................................................................................54
7.2.
Patient Discontinuation/Withdrawal from the Study..................................................54
7.3.
Lost to Follow up ........................................................................................................55
8.
STUDY ASSESSMENTS ..........................................................................................56
8.1.
Efficacy Assessments .................................................................................................56
8.1.1. 
Response Determination according to 2014 NIH Consensus definitions...................56
8.1.2. 
Response Determination for Pediatric Patients ..........................................................57
8.1.3. 
Physician-Reported Global and Organ Specific cGVHD Activity 
Assessment .................................................................................................................57
8.1.4. 
Patient-Reported cGVHD Activity Assessment (mLSS) ...........................................57
8.2.
Safety Assessments.....................................................................................................58
8.2.1.
Physical Examinations................................................................................................58
8.2.2. 
Neurological Examinations ........................................................................................58
8.2.3. 
Vital Signs ..................................................................................................................58
8.2.4. 
Electrocardiograms .....................................................................................................58
8.2.5. 
Karnofsky/Lansky Performance Status ......................................................................59
8.2.6. 
Clinical Safety Laboratory Assessments ....................................................................60
8.3.
Adverse Events and Serious Adverse Events .............................................................60
8.3.1. 
Time Period and Frequency for Collecting AE and SAE Information .......................60
8.3.2. 
Method of Detecting AEs and SAEs ..........................................................................61
8.3.3. 
Follow-up of AEs and SAEs.......................................................................................61
8.3.4. 
Regulatory Reporting Requirements for SAEs...........................................................62

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8.3.5. 
Pregnancy ...................................................................................................................62
8.3.6.
Disease-Related Events and/or Disease-Related Outcomes Not Qualifying as 
AEs or SAEs...............................................................................................................62
8.4.
Treatment of Overdose ...............................................................................................63
8.5.
Pharmacokinetics........................................................................................................63
9.
STATISTICAL CONSIDERATIONS .......................................................................65
9.1.
Statistical Hypothesis..................................................................................................65
9.2.
Sample Size Determination ........................................................................................65
9.3.
Population for Analyses..............................................................................................65
9.4.
Statistical Methods......................................................................................................66
9.4.1. 
Efficacy Analysis ........................................................................................................66
9.4.2. 
Safety and Tolerability Analysis ................................................................................68
9.4.3. 
Pharmacokinetic Analyses..........................................................................................69
9.4.5. 
Interim Analysis..........................................................................................................70
10.
APPENDICES ............................................................................................................72
10.1.
Appendix 1: Regulatory, Ethical, and Study Oversight Considerations ....................72
10.1.1. 
Regulatory and Ethical Considerations ......................................................................72
10.1.2. 
Informed Consent Process..........................................................................................72
10.1.3. 
Data Protection ...........................................................................................................73
10.1.4.
Independent Data Monitoring Committee..................................................................73
10.1.5. 
Dissemination of Clinical Study Data ........................................................................74
10.1.6. 
Data Quality Assurance ..............................................................................................74
10.1.7. 
Source Documents ......................................................................................................75
10.1.8. 
Study and Site Closure................................................................................................75
10.1.9. 
Publication Policy.......................................................................................................75
10.2.
Appendix 2: Clinical Laboratory Tests.......................................................................76
10.3.
Appendix 3: Adverse Events: Definitions and Procedures for Recording, 
Evaluating, Follow-up, and Reporting........................................................................78
10.3.1. 
Definition of AE .........................................................................................................78
10.3.2. 
Definition of SAE .......................................................................................................79

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10.3.3. 
Definition of Adverse Events of Special Interest (AESI)...........................................79
10.3.4.
Definition of Suspected and Unexpected Adverse Reaction......................................80
10.3.5.
Recording, Assessment, and Follow-Up of AE and/or SAE......................................80
10.3.6. 
Reporting of SAEs and AESI .....................................................................................82
10.4.
Appendix 4: Contraceptive Guidance and Collection of Pregnancy 
Information .................................................................................................................83
10.5.
Appendix 5: Rating Scales..........................................................................................86
10.5.1.
Global cGVHD Activity Assessment – Clinician Report...........................................86
10.5.2. 
cGVHD mLSS ............................................................................................................89
10.6.
Appendix 6: Abbreviations.........................................................................................90
11.
REFERENCES ...........................................................................................................92
 

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LIST OF TABLES
Table 1
Schedule of Activities.................................................................................................21
Table 2
PK Collection Schedule..............................................................................................25
Table 3
Study Intervention ......................................................................................................42
Table 6
Other Non-hematologic Toxicity: Dose Modification Guidelines for 
Axatilimab ..................................................................................................................48
Table 7
Hematologic Toxicity: Dose Modification Guidelines for Axatilimab......................49
Table 8
Guidance for Treatment of Infusion-related Reactions ..............................................50
Table 9
Response Determination for Chronic GVHD Clinical Studies based on 
Clinician Assessments ................................................................................................56
Table 10 
Karnofsky/Lansky Performance Status ......................................................................59
Table 11 
Adverse Event Observation Periods ...........................................................................61
Table 12 
Interim Analysis #1 Toxicity Stopping Boundaries (Rate = 0.20 with Prior 
[1,1] and Posterior Prob. of 0.90) ...............................................................................71
Table 13 
Protocol-Required Safety Laboratory Assessments ...................................................76
Table 14 
Highly Effective methods of contraception (<1% failure rate) ..................................84

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LIST OF FIGURES
Figure 1 
Swimmer Lane Plot by Phase and Cohort Showing Duration on Study Drug 
and Responses as of 22 October 2021 ........................................................................29

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1.
PROTOCOL SUMMARY
1.1.
Synopsis
Protocol Title:
AGAVE-201, A Phase 2, Open-label, Randomized, Multicenter Study to Evaluate the Efficacy, 
Safety and Tolerability of Axatilimab at 3 Different Doses in Patients with Recurrent or 
Refractory Active Chronic Graft Versus Host Disease who have Received at least 2 Lines of 
Systemic Therapy.
Short Title:
Phase 2 Study of Axatilimab at 3 Different Doses in Patients with Chronic Graft Versus Host 
Disease. 
Rationale:
Chronic graft-versus-host disease (cGVHD) remains the major cause of morbidity and non-
relapse mortality after allogeneic hematopoietic stem cell transplantation (HSCT). cGVHD 
typically manifests with multiorgan pathology which often occurs during the first-year 
post-HSCT but can also develop beyond the first year post-HSCT (Jagasia 2015).
Treatment of cGVHD is currently based on steroid administration and although many other 
approaches, including additional immune suppressants, ultraviolet B (UVB) phototherapy, and 
extracorporeal photopheresis (ECP) are commonly used, none have proven clearly effective. 
Targeting pathogenic monocyte derived macrophages by preventing their differentiation and 
survival through the inhibition of colony stimulating factor 1 receptor (CSF-1R) has proven 
highly effective in animal systems. 
Axatilimab is a humanized IgG4 monoclonal antibody (mAb) directed against CSF-1R with the 
potential to treat cGVHD through blockade of macrophage activity. 
Data from the current axatilimab Phase 1/2 study in patients with cGVHD (SNDX-6352-0503) 
demonstrate that axatilimab is biologically and clinically active, inducing organ specific 
responses and symptom improvement, with no significant adverse events. These data support 
evaluation of axatilimab as described in the proposed registration enabling Phase 2 study, 
SNDX-6352-0504.

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Objectives and Endpoints: 
Objectives
Endpoints
Primary 
To evaluate the overall 
response rate (ORR) of 
axatilimab at 0.3 mg/kg IV 
Q2W, 1 mg/kg IV Q2W, and 
3 mg/kg IV Q4W in patients 
with cGVHD after failure of 
least 2 prior lines of therapy. 
 
ORR in the first 6 cycles as defined by the 2014 NIH 
Consensus Development Project on Criteria for Clinical 
Trials in cGVHD. 
Key Secondary - Efficacy 
 
To evaluate key secondary 
measures of clinical benefit 
 
Proportion of patients with a clinically significant 
improvement in modified Lee Symptom Scale score (mLSS). 
Secondary - Efficacy  
 
To evaluate secondary 
measures of clinical benefit. 
 
ORR on study as defined by the 2014 NIH Consensus 
Development Project on Criteria for Clinical Trials in 
cGVHD. 
 
Duration of Response (DOR) defined as the time from initial 
response of PR or CR until documented progression of 
cGVHD, start of new therapy, or death for any reason. 
 
Sustained response rate (SRR) 
 
Organ-specific response rate based on 2014 NIH Consensus 
Development Project on Criteria for Clinical Trials in 
cGVHD  
 
Joints and fascia response rate based on refined NIH response 
algorithm for cGVHD (Inamoto 2020) 
 
Percent reduction in average daily dose (or equivalent) of 
corticosteroids  
 
Proportion of patients who discontinue corticosteroid use 
after study entry. 
 
Percent reduction in average daily dose (or equivalent) of 
calcineurin inhibitors  
 
Proportion of patients who discontinue calcineurin inhibitors 
use after study entry 

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Objectives 
Endpoints 
Secondary – Safety 
 
To evaluate the safety and 
tolerability of axatilimab in 
patients with cGVHD 
 
Frequency and severity of adverse events (AEs) and serious 
adverse events (SAEs) 
 
Change from baseline in values for vital signs, safety 
laboratory parameters, physical and neurological 
examination, electrocardiogram (ECG) and 
Karnofsky/Lansky performance scale 
Secondary - PK/Pharmacodynamic 
 
To assess the plasma 
population PK (pop PK) 
profile of axatilimab in 
patients with cGVHD 
 
Axatilimab PK parameters and patient factors that may 
explain variability in drug exposure 
 
To assess pharmacodynamic 
profile of axatilimab 
 
Change from baseline in colony stimulating factor 1 (CSF-1), 
interleukin 34 (IL-34) levels and its association with cGVHD 
response 
 
To determine or assess the 
changes in monocyte level 
with response 
 
Change from baseline in circulating monocyte number and 
phenotype (CD14/16) 
 
To determine or assess the 
baseline in monocyte level 
with response 
 
Baseline circulating monocyte number and phenotype 
(CD14/16) 
Secondary – Immunogenicity 

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Objectives 
Endpoints 
Exploratory – Efficacy
 
To explore possible additional 
evidence of clinical benefit. 
 
Proportion of patients with Failure Free Survival (FFS) at 
Cycle 7 Day 1 and 1 year. FFS is defined as the time from 
randomization to addition of another systemic immune 
suppressive therapy for cGVHD, relapse of underlying 
malignancy, or death whichever is earlier. 
 
Overall survival (OS) 
 
Time to response 
Overall Design:
AGAVE-201 is a Phase 2, open-label, randomized, multicenter study to evaluate the efficacy, 
safety and tolerability of axatilimab at 3 different dose levels, in patients with recurrent or 
refractory active cGVHD who have received at least 2 prior lines of systemic therapy due to 
progression of disease, intolerability or toxicity. Disease progression is defined 1) by the NIH 
2014 consensus criteria, either in terms of organ specific algorithm or global assessment or, 2) as 
active, symptomatic cGVHD for whom the physician believes that a new line of systemic 
therapy is required.
The study will consist of 3 periods: Screening, Treatment, and Follow-up. Throughout the study, 
patients will be evaluated as specified in the Schedule of Activities (SoA) (Section 1.2). 
After signing informed consent, potential candidates will undergo screening procedures to 
determine eligibility. At enrollment, eligible patients will be randomized to one of 3 dose cohorts 
(axatilimab 0.3 mg/kg IV every 2 weeks [Q2W], 1 mg/kg IV Q2W, or 3 mg/kg IV Q4W). 
Patients must begin treatment (Cycle 1 Day 1) within 3 days of randomization/enrollment and 
will receive axatilimab from Cycle 1 Day 1, in 4-week (28-day) treatment cycles, until disease 
progression (as defined by the NIH 2014 consensus criteria), lack of efficacy by 9 months 
(Section 6.7.2), withdrawal of consent, or unacceptable toxicity. Following treatment 
discontinuation, patients will receive an End of Treatment (EOT) visit 30 days after the last dose 
of study drug.  

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Simon’s optimal 2-stage design will be implemented within each dose cohort. In the first stage 
27 patients will be randomized to each of the 3 dose cohorts. To limit the potential exposure of 
patients to an inefficacious dose and obviate the need for a pause in accrual, the initial futility 
analysis will be based on an early endpoint (ie, overall response in the first 3 cycles). Each dose 
will be evaluated for futility and unacceptable toxicity as follows: 
 Interim Analysis (IA)  #1: Futility assessment based on responses in the first 3 
cycleswill be conducted. This assessment will occur when the first 27 patients in each 
cohort have had the opportunity to complete 3 cycles of t
a response after the first 3 cycles of axatilimab (up to and including cycle 4, day 1 
assessment), the randomization to this dose level may be stopped for futility. Safety 
assessment will occur at this IA. For IA # 1, the boundary for unacceptable toxicity is 
 3) TEAE that is attributed to study drug. Grade 2 events that are considered 
treatment-related and result in medical intervention or hospitalization will be counted 
as a toxic event. 
 IA #2: IA #2 will consist of an overall evaluation of available clinical data. It will be 
conducted when the first 27 patients in each cohort have had the opportunity to 
complete 6 cycles of therapy. 
randomization to this dose level will be stopped for futility. For IA#2, given the full 
enrollment of the study as of this amendment, the rate of toxicity events will be 
provided for all treated patients and will be reviewed as part of the overall benefit/risk 
assessment. For the overall benefit/risk assessment, a comprehensive safety and 
efficacy analysis will be provided to the IDMC:
 Safety for all participants. 
 Efficacy for all participants who have had the opportunity to receive 3 cycles of 
axatilimab. 
Study randomization will not pause while data from the interim analyses are being evaluated.  
An Independent Data Monitoring Committee will evaluate all data that are available at the time 
of the data cut for the interim analyses, and provide a recommendation on continued use of the 
available axatilimab dose levels.  
A final efficacy analysis will be performed when all patients have had the opportunity to 
complete 
patients have had a response to axatilimab (PR or CR), as defined by NIH 2014 cGVHD criteria. 
The final boundary for efficacy will be re-calculated if there is over enrollment in the second 
stage of the design. For example, if the total number of randomized patients in a dose level is 80, 
 
At the final analysis, if 19 or more patients out of the total 70 patients experience a toxic event 
(the boundary will be re-calculated if there is over enrollment), this will indicate a 90% posterior 
probability of the toxicity rate exceeding 20% but the final determination of acceptability of a 
given dose will be based on the overall benefit/risk indicated by review of the totality of 
evidence. 

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Patients enrolled into a Q2W regimen may be eligible to change to a Q4W dosing during the 
study, as described in Section 6.3. Additional dosing modifications for already enrolled patients 
may be implemented following IDMC recommendation on closing enrollment to one or more 
dose level cohorts and are specified in Section 6.2.1.  
The on-treatment response criteria will be assessed every 4 weeks and at the EOT visit or 
discontinuation of the study intervention using 2014 NIH Consensus Development Project on 
Criteria for Clinical Trials in cGVHD: CR, PR, lack of response (unchanged, mixed or 
progression).
Disclosure Statement:  
 Stage 1 is to evaluate each dose regimen for efficacy and safety; with futility IA. 
 Stage 2 is to evaluate the efficacy and safety of axatilimab at the selected dose(s).
Number of Patients:
 In Stage 1, 27 patients will be enrolled into each treatment arm (0.3 mg/kg IV Q2W, 1 
mg/kg IV Q2W, and 3 mg/kg IV Q4W). 
 In Stage 2, an additional 43 patients will be enrolled into each of the treatment arms 
which have passed the futility and safety evaluations from Stage 1. 
Dosing Arms and Duration of Treatment:
There will be 3 dosing arms: 0.3 mg/kg IV Q2W, 1 mg/kg IV Q2W, and 3 mg/kg IV Q4W. Total 
study duration for each patient will be up to 28 months as follows:
Screening period:  
Up to 28 days (1 month) prior to the first dose of study 
intervention 
Treatment period:  
Until unequivocal disease progression or unacceptable 
toxicity up to a maximum period of 2 years. Patients who 
continue to derive benefit after 2 years of treatment, 
administration may continue following consultation with 
sponsor.
Safety Follow-up period:  
Up to 90 days (3 months) after the last administration of 
study intervention 
Overall Survival Follow-
up period:
After completing safety follow-up, patients will be contacted 
every 3 months to assess overall survival for up to 5 years.
End of Study 
The final contact with the last patient for survival follow-up.
Dosing Methods:
Patients will receive axatilimab IV at a dose and regimen according to the dosing cohort that they 
are randomized to as follows: 
 0.3 mg/kg IV Q2W 

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 1 mg/kg IV Q2W  
3 mg/kg IV Q4W
Independent Data Monitoring Committee: Yes

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1.3. 
Schedule of Activities (SoA)  
 
Table 1 
Schedule of Activities 
Study Procedure 
Screening
Treatment Period 
Safety 
Follow-Up
OS  
Follow-Up
Cycle (each cycle consists of 28-days)
Cycle 1 
Cycles 2 to 6 
Cycle 
7-241 
Cycle 25+ 
Days post last dose 
±7 days 
Up to 5 years after 
Cycle 1 day 1 
Day in Cycle
-28 to 0
1
8
15
22
1
15
1/15
1/15
+302 
(EOT) 
+60
+90
Every 3 months
Visit Window 
NA 
NA 
±1D 
±1D 
±1D 
±3D 
±3D 
±3D 
±3D 
±7D 
±7D 
±7D 
±15D 
Informed consent 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Demographics3
X
Eligibility criteria
X
Medical & disease 
history4 & prior 
medications 
X 
 
 
 
 
 
 
 
 
 
 
 
 
Karnofsky/Lansky 
Performance Scale 
X
X
X
X5
X
X
X
Complete physical 
examination 
X 
X6
X
X
X
Height
X
Randomization7
X
Symptoms-directed 
physical exam 
X
X
X
X
X
X
X
 
 
 
 
Vital signs9 and weight
X
X
X
X
X
X
X
X
X
X
X
X

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Study Procedure 
Screening
Treatment Period 
Safety 
Follow-Up
OS  
Follow-Up
Cycle (each cycle consists of 28-days)
Cycle 1
Cycles 2 to 6
Cycle 
7-241 
Cycle 25+
Days post last dose 
±7 days 
Up to 5 years after 
Cycle 1 day 1 
Day in Cycle 
-28 to 0 
1 
8 
15 
22 
1 
15 
1/15 
1/15 
+302 
(EOT)
+60 
+90 
Every 3 months 
Visit Window
NA
NA
±1D
±1D
±1D
±3D
±3D
±3D
±3D
±7D
±7D
±7D
±15D
Neurological examination
X
X
X
X5
X
X
X
12-Lead 
Electrocardiogram 
X 
As clinically indicated 
X 
 
 
 
Pulmonary Function 
Tests10 
X 
 
 
 
X 
 
X10
Safety Laboratory 
(hematology, & 
biochemistry)11
X 
X 
X 
X 
X 
X 
X 
X12 
X12
X 
X 
 
 
Coagulation factors
X
X13
HCV RNA15
X
HBV16
X
TB17
X
Urinalysis
X
As clinically indicated
X
 
 
 
Pregnancy testing18
X
X19
X19
X19
X19
X18
Axatilimab administration
X
X20
X
X20
X20
X20
Adverse events 
X
X
X
X
X
X
X
X
X
X
X
X
Concomitant medications
X
X
X
X
X
X
X
X
X
X
X
X

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Study Procedure 
Screening
Treatment Period 
Safety 
Follow-Up
OS  
Follow-Up
Cycle (each cycle consists of 28-days)
Cycle 1
Cycles 2 to 6
Cycle 
7-241 
Cycle 25+
Days post last dose 
±7 days 
Up to 5 years after 
Cycle 1 day 1 
Day in Cycle 
-28 to 0 
1 
8 
15 
22 
1 
15 
1/15 
1/15 
+302 
(EOT)
+60 
+90 
Every 3 months 
Visit Window
NA
NA
±1D
±1D
±1D
±3D
±3D
±3D
±3D
±7D
±7D
±7D
±15D
Physician-reported 
cGVHD global activity 
assessment21, 22 
X
X
X23
X
Patient cGVHD Self-
Assessment (mLSS) 
X
X
X23
X
Pharmacokinetics  
 
See Table 2 for collection times
Pharmacodynamics
See Table 2 for collection times
Tissue biopsy25
X
X26
Overall survival 
X27
Abbreviations: 
 HBV = hepatitis B virus; HCV RNA = hepatitis C 
virus ribonucleic acid; mLSS = modified Lee Symptom Scale; TB = tuberculosis 
1. Patients who meet the criteria detailed in Section 6.3 may change their dosing schedule. The Day 15 visit is only applicable for patients on a Q2W regimen. 
2. In case of early discontinuation, this visit (30 days after last dose of study intervention) will serve as end of study visit. 
3. Includes age, race, and ethnicity.
4. A complete medical history will be documented and updated prior to the administration of the first dose of study intervention. The medical history will include cancer history, 
including date of and stage at diagnosis, method of diagnosis, all previous treatments and response to such treatment, and any medical condition that might complicate the 
patient’s disease or affect the treatment outcome. 
5. Assessment to be performed on Day 1 of each cycle.
6. If the Screening complete physical exam was performed within 7 days before C1D1, a symptom-directed physical exam may be performed at randomization. 
7. Patients must be randomized within 3 days prior to C1D1. 

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9. Vital signs should be performed before every infusion. In addition, for the first 2 infusions, they should also be performed during and after the infusion. Thereafter (from the 
third infusion on), they should be performed during or after the infusion, if clinically indicated. 
10. Age-appropriate Pulmonary Function Tests (PFTs) performed within 4 weeks prior to the scheduled first dose for all patients. For patients with documented lung involvement, 
frequency beyond C1 will be every 3 cycles (±7 days) up to and including C24. 
11. For all patients, labs should be taken at each visit in Cycle 1, for Cycle 1 Day 1 labs may be drawn up to 2 days prior to dosing. From Cycle 2 on, labs should be taken up to 2 
days prior to each dose but within the visit window. In Cycle 2 for patients on the Q4W regimen, labs do not need to be drawn on Day 15 of each cycle. Refer to Appendix 2 
(Section 10.1) for full list of clinical laboratory tests. Maximum daily blood draw from a patient weighing 41-45 kg (equating to a patient of approximately 12 years of age) is 
160 mL (5% blood volume) and maximum blood draw over 8 weeks is 320 mL (10% blood volume). When adding up all blood draws, including those detailed in Table 
1/Table 2, the maximum blood volume to be drawn on any one day will be 63.5 mL and the total blood to be drawn over the first 60 days (through Cycle 3 Day 1) will be 284.5 
mL. If urea level is reported by the local site laboratory instead of blood urea nitrogen (BUN), BUN level should be calculated formulas detailed in Section 10.2 and entered in 
the appropriate field in the eCRF. 
12. Labs should only be taken on Day 15 of each cycle if clinically indicated. 
13. On Cycle 3 Day 1 only, if the patient is having a skin biopsy, the coagulation sample should be collected first (ie, before the skin biopsy). 
14. To be collected on C1D1, C3D1, C6D1, C12D1 and EOT, samples should be collected pre-dose. 
15. Polymerase chain reaction is required and must be negative for HCV RNA in patients positive for HCV antibody. 
16. Hepatitis B screening: hepatitis B surface antigen, hepatitis B surface antibody, hepatitis B core antibody, immunoglobulin G and M. 
17. Evidence of negative QuantiFERON test within 28 days prior to the first dose of axatilimab. 
18. For female patients of child-bearing potential, a serum pregnancy test is required to be performed during screening and within 3 days before the first study intervention dose if 
the screening pregnancy test is performed more than 3 days before the first study intervention dose. A serum pregnancy is also required at the end of study. During the study, 
either urine or serum pregnancy tests are performed. 
19. Pregnancy testing is to be repeated every 4 weeks from Cycle 1 Day 1. 
20. Patients receiving axatilimab on a Q4W regimen will only be administered study drug on Day 1 of each cycle (not on Day 15). 
21. Response evaluation will be according to 2014 NIH Consensus definitions; Window periods of ±3 days will be allowed for each response assessment (unless otherwise 
specified). 
22. It is preferred that all cGVHD assessments be done by the same health care provider who completed the C1D1 assessment. At minimum, the C7D1 assessment should be 
performed by the same health care provider who performed the C1D1 assessment. In addition, any assessments leading to changes in cGVHD therapy must be confirmed by 
the PI or primary treating physician. 
23. Assessments should be made D1 of each cycle C7-C12 inclusive. Cycle 13-24 assessments should be made every 12 weeks. 
 
25. Optional skin biopsy only in patients with skin cGVHD; optional lung biopsy only in patients with transbronchial lung cGVHD. 
26. Optional biopsy will be done on C3D1. 
27. After completing safety follow-up, patients will be contacted every 3 months to assess for any long-term safety signal such as secondary malignancies or chronic infection and 
overall survival for up to 5 years. 

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Table 2
PK Collection Schedule
C1
C2
C3
C4
C5 to C12
 
Day 1 
Day 8 
Day 15 
Day 221 
Day 1 
Day 1 
Day 1 
Day 1 
Sample 
PK 
PD 
PK 
PD 
PK2 
PD 
PK 
PD 
PK 
PD 
PK 
PK 
PD 
PK 
Predose3 
X
X
X4
X
X
X
X
X
X
X
X
X
X
X
30 min (immediately after the 
end of infusion) (+5 min) 
X
X
X
1 hour (after infusion start) (±5 
min) 
X 
 
X 
 
 
 
 
X 
 
 
6 hours (after infusion start) 
(±10 min) 
X
X
X
Total blood volume (mL)5
24
22
6
22
24
22
6
3
6
22
6
24
22
6
Abbreviations: PD = pharmacodynamics; PK = pharmacokinetics
1. For patients on a Q4W regimen.  
2. A single PK sample should be collected on Day 15 for patients on a Q4W regimen. 
3. On days patients receive an SNDX-6352 dose samples will be collected pre-dose. 
4. This sample may be taken ±24 hours. 
5. Maximum daily blood draw from a patient weighing 41-45 kg (equating to a patient of approximately 12 years of age) is 160 mL (5% blood volume) and maximum blood draw 
over 8 weeks is 320 mL (10% blood volume). When adding up all blood draws, including those detailed in Table 1/Table 2, the maximum blood volume to be drawn on any 
one day will be 63.5 mL and the total blood to be drawn over the first 60 days (through Cycle 3 Day 1) will be 284.5 mL. 

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2.
INTRODUCTION
2.1.
Study Rationale and Hypothesis
Chronic graft versus host disease (cGVHD) remains the major cause of morbidity and 
non-relapse mortality after allogeneic hematopoietic stem cell transplantation (HSCT). cGVHD 
typically manifests with multiorgan pathology which often occurs during the first-year 
post-HSCT but can also develop beyond the first year post-HSCT (Jagasia 2015). Treatment of 
cGVHD is currently based on steroid administration. While progress has been made with 
improvements in survival outcomes over time, current available therapies are associated with 
significant toxicities, and many currently available salvage therapies are associated with 
increased immunosuppression, infectious complications, and potential loss of the graft versus 
leukemia (GVL) effect. Thus, there is an unmet need for development of newer treatment 
strategies for cGVHD to improve long-term post-transplant outcomes and quality of life for 
HSCT recipients (Hill 2018).  
Based on nonclinical pharmacology studies in mouse models of interleukin (IL)-17 dependent 
skin and lung GVHD it was demonstrated that targeting CSF-1/CSF-1R signaling pathway 
prevents and treats cGVHD through depletion of donor-derived macrophages (Alexander 2014). 
These studies established that donor bone marrow derived macrophages were responsible for 
generating the fibrotic disease symptoms of cGVHD and that with blockade of colony 
stimulating factor 1 (CSF-1) dependent monocyte recruitment, differentiation and proliferation 
ameliorated and prevented the development of cGVHD. In these nonclinical models, depletion of 
macrophages using an anti-CSF-1R mAb markedly reduced cutaneous and pulmonary cGVHD. 
Taken together, these data support a key role for donor-derived macrophages in the development 
of cGVHD and suggest that targeting CSF-1 signaling after transplantation may prevent and treat 
cGVHD (reviewed in MacDonald, 2017). 
Axatilimab is a humanized IgG4 monoclonal antibody (mAb) with high affinity against CSF-1R. 
Axatilimab can affect the migration, proliferation, differentiation, and survival of circulating 
monocyte populations and monocyte derived macrophages by binding to CSF-1R and blocking 
activation by its two known ligands, colony stimulating factor-1 (CSF-1) and interleukin-34 (IL-
34).  
Currently, axatilimab is being evaluated in a Phase 1/2 study in patients with cGVHD who have 
received at least two lines of prior therapy (SNDX-6352-0504). A summary of the study 
including preliminary safety, pharmacokinetic (PK), pharmacodynamic, and clinical response 
data is provided in Section 2.2.1. 
 
 
  
These data support evaluation of axatilimab as described in the proposed registration enabling 
Phase 2 study, SNDX-6352-0504; a study evaluating the efficacy, safety, and tolerability of 
 of systemic therapy due to 
progression of disease, intolerability or toxicity. 

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2.2.
Background
cGVHD is an immune-mediated serious and life-threatening complication after allogeneic 
HSCT, occurring in 30% to 70% of patients (Jagasia 2015, Merkel 2016). The prevalence and 
severity of cGVHD have increased during the past 2 decades in association with the increasing 
use of hematopoietic HSCT, the widespread use of mobilized blood cells instead of marrow for 
grafting, and improvements in survival during the first several months after allogeneic HSCT 
(Flowers and Martin 2015). 
The disease has a wide range of pleomorphic manifestations, and many complications can 
emerge from both the disease and its treatment. It is a chronic illness that can have devastating 
effects on quality of life. Clinical manifestations can impair activities of daily living and often 
linger for years. Manifestations of chronic GVHD can resemble autoimmune or other immune-
mediated disorders such as scleroderma, Sjögren syndrome, primary biliary cirrhosis, 
bronchiolitis obliterans, immune cytopenias, and chronic immunodeficiency. cGVHD generally 
involves several organs or sites, patients frequently have erythematous rash, enteritis, or hepatic 
involvement characterized by transaminase elevation or hyperbilirubinemia at initial presentation 
and intermittently afterward during the course of the disease. Manifestations typically appear 
within the first year after HSCT, most often when doses of immunosuppressive medications are 
weaned. The disease can begin as early as 2 months and as late as 7 years after HSCT, although 
onset at >1 year from HSCT occurs in <10% of cases (Flowers and Martin 2015).  
The 2005 National Institutes of Health (NIH) Consensus Conference developed a framework for 
characterizing the pleomorphic manifestations of chronic GVHD. The consensus project defined 
minimal criteria for the clinical diagnosis, established criteria for scoring the severity of clinical 
manifestations in affected organs and proposed new categories for describing overall disease 
severity and indications for treatment. The consensus project also proposed measures for 
monitoring disease progression and response to therapy. It provided guidance for clinical trials to 
support bringing forward therapies that will provide a durable meaningful difference to patients’ 
clinical symptoms and quality of life. In 2014, the NIH Conference was reconvened and the 
proposed revisions, based on ongoing clinical evaluation of the disease, were incorporated. The 
NIH guidance has been supported by the US Food and Drug Administration (FDA) as an 
appropriate means to measure disease and response to therapy. 
While the pathophysiological understanding of cGVHD is emerging, there has been little 
meaningful development of therapies for patients with cGVHD. Currently, there remains a long-
standing reliance on prednisone as the mainstay of treatment. Steroid administration can relieve 
symptoms and delay disease progression; however, this approach is associated with significant 
toxicity and emergence of resistance (Flowers and Martin 2015, MacDonald 2017). An effort to 
decrease corticosteroid doses has led to their use in combination with other immunosuppressants, 
such as cyclosporine, tacrolimus, and sirolimus, in frontline or second-line settings, despite a 
lack of clinical evidence supporting additional efficacy after combining these agents with 
corticosteroids (Miklos 2017). 
Approximately 50% to 60% of patients with cGVHD require secondary treatment within 2 years 
after initial systemic treatment. Despite no consensus with respect to optimal choice of agent, 
they have typically included rituximab or imatinib (Flowers and Martin 2015). In 2017 
Imbruvica® (ibrutinib), a BTK inhibitor, became the first FDA approved therapy for the 

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therapy. The side effects of ibrutinib are significant with 38% of patients discontinuing due to an 
adverse event and 31% of patients dose reducing in the pivotal evaluation of ibrutinib in patients 
with cGVHD. Additionally, investigators have noted that they do not give ibrutinib to a large 
proportion of their cGVHD patients due to the organ system involvement of the patients that 
participated in the clinical development program.  
Based on recent insights into the molecular mechanisms involved in the disease-related 
inflammatory process, interventions targeting kinases involved in signaling pathways such as 
BTK, JAK1/2, Syk, and ROCK2 have been investigated and have shown promising results in 
nonclinical and patient sample correlative studies (MacDonald 2017); BTK and ROCK2 
inhibition have shown evidence of efficacy in Phase 1/2 clinical studies (Miklos 2017). 
2.2.1. 
Clinical Experience with Axatilimab in Patients with cGVHD 
SNDX-6352-0503 is a Phase 1 dose-finding and Phase 2 dose-expansion study evaluating the 
safety, tolerability, PK/pharmacodynamic, and efficacy of axatilimab in patients with active 
cGVHD whose disease has progressed after having received at least 2 prior lines of therapy. As 
of 22 October 2021, 40 patients had received at least 1 dose of study drug: 17 patients in the 
Phase 1 dose-escalation portion and 23 in a Phase 2 dose-expansion cohort. A summary of these 
patients as of the data cutoff is provided below. 
The 17 patients in the Phase 1 portion of the study have been dosed IV across four Q2W dose 
levels (0.15 mg/kg and 0.5 mg/kg [1 patient, each], 1 mg/kg [3 patients], 3 mg/kg [6 patients]) 
and one Q4W dose level (3 mg/kg [6 patients]). The 23 patients in the Phase 2 portion have been 
dosed IV at 1 mg/kg Q2W. As of the data cutoff, 17 patients were still receiving study drug 
including 5 patients in Phase 1 (1 mg/kg IV Q2W [1 patient], 3 mg/kg IV Q2W [2 patients] and 
3 mg/kg IV Q4W [2 patients]) and 12 patients in Phase 2. 
Ninety-eight percent of patients experienced at least 1 treatment emergent adverse event (TEAE) 
as of the data cutoff. One patient in 1 mg/kg IV Q2W (Phase 2) had not reported any TEAEs. 
Two patients reported 1 event each that was considered a dose limiting toxicities (DLT) both 
dosed with axatilimab 3 mg/kg IV Q2W (creatine phosphokinase [CPK] increase and an increase 
in amylase and lipase which required a 3-week delay in the patient’s third dose). Eight patients 
blood CPK increased (3 mg/kg Q2W, 
2 patients and 3 mg/kg IV Q4W, 1 patient); aspartate aminotransferase (AST) increased 
(0.15 mg/kg and 3 mg/kg Q2W, 1 patient each); gamma-glutamyl transferase (GGT) increased 
(0.15 mg/kg and 3 mg/kg Q2W, 1 patient each); lipase increased (3 mg/kg IV Q2W and 3 mg/kg 
IV Q4W, 1 patient each); hypersensitivity (1 mg/kg IV Q2W, 1 patient); periorbital oedema (3 
mg/kg IV Q4W, 1 patient); and septic arthritis staphylococcal (1 mg/kg IV Q2W, 1 patient). Four 
patients reported 7 serious related TEAEs as follows: abdominal distension, face oedema, 
hypersensitivity, neuropathy peripheral, oedema peripheral, and septic arthritis staphylococcal (1 
mg/kg IV Q2W, 1 patient each); and pyrexia (3 mg/kg IV Q2W, 1 patient)

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Biochemical elevations reflect a consequence of CSF-1R blockade on Kupffer cells leading to an 
inhibition in the clearance of these enzymes, consistent with the mechanism of action of 
axatilimab and when asymptomatic have not been associated with clinical manifestations of 
hepatitis, pancreatitis, or rhabdomyolysis. Periorbital edema was observed in 2
2); no additional CSF-1Ri class-effect associated TEAEs were observed.
Preliminary PK data are available from 7 of the 11 patients enrolled in the study as of 
30 March 2020. 
 
 A dose-dependent increase in exposure was observed in 
groups given 0.15 to 3 mg/kg of drug. The Cmax followed this trend and was consistent with other 
studies evaluating axatilimab. 
 
 
As of 22 October 2021, all but 12 patients had received at least 16 weeks of study treatment 
including 23 patients who had completed at least 24 weeks of study treatment. Of the 12 patients 
who had not received 16 weeks of study treatment, 6 came off study due to progressive disease 
or investigator decision and 6 discontinued treatment due to an adverse event or other reason. Of 
the 23 patients who had completed at least 24 weeks of study treatment, 17 were ongoing at the 
data cutoff. Duration of treatment and patient responses are shown in Figure 1. 
Figure 1
Swimmer Lane Plot by Phase and Cohort Showing Duration on Study Drug 
and Responses as of 22 October 2021
As of 22 October 2021, all overall responses were partial response (PR) according to the 
2014 NIH Consensus Development Project on Criteria for Clinical Trials in cGVHD (NIH 
Consensus Criteria). PRs or complete responses (CRs) have been observed in the esophagus, 
eyes, skin, joints/fascia, and mouth. 
0
8
16
24
32
40
48
56
64
72
80
88
96
104
112
120
128
136
Time on Study (Weeks)
1
1
3
2
2
2
1
2
1
2
5
3
4
2
4
2
6
6
1
2
4
5
1
1
1
3
8
2
3
9
3
0
2
5
6
4
3
4
1
Dose Limiting Toxicities
Progressive Disease
Adverse Event
Investigator Decision
Other [1]
Withdrawal Of Consent
Ongoing at Data Cutoff
CR/PR
0.15 mg/kg q2w Phase 1
0.5 mg/kg q2w Phase 1
1 mg/kg q2w Phase 1
1 mg/kg q2w Phase 2
3 mg/kg q4w Phase 1
3 mg/kg q2w Phase 1

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2.3.
Benefit and Risk Analysis
To date, available axatilimab nonclinical and clinical data support clinical investigation in 
patients with cGVHD. The axatilimab IB provides a summary of known and expected benefits 
and risks of axatilimab. 
 
  
Due to the axatilimab mechanism of action (pharmacological inhibition of CSF-1R), axatilimab 
may induce dose-dependent and reversible increases in circulating levels of CPK, AST, alanine 
aminotransferase (ALT), glutamate dehydrogenase (GLDH), amylase and lipase (see IB for 
details). Kupffer cells in the liver (which are involved in the clearance of these enzymes) are in 
the macrophage lineage and susceptible to axatilimab inhibition of CSF-1R. The expected 
increases in these enzyme levels are related to decreased clearance from the blood, rather than 
from drug-induced liver injury and are not associated with any histopathological change. 
Laboratory assessments (ie, clinical chemistries, including tests for liver function) will be 
performed as specified in protocol to monitor patient’s safety. Similarly, prolonged anti–CSF-1R 
blockade eliminates osteoclasts and is associated with increased levels of bone turnover markers, 
with preclinical studies supporting an overall positive impact on bone density and trabecular 
bone volume (Sauter 2014; Ambrosi 2021). 
 
  
Given the mechanism of action and clinical experience with axatilimab thus far, there are no 
ongoing or planned toxicity studies in animal models, including juvenile animal models. 
Responses have been observed across all axatilimab dose levels evaluated in a pretreated 
cGVHD population (Figure 1). Three dose levels have been selected for evaluation across a 
range of doses which to date have been tolerable and manageable. This study will seek to address 
the fact that the minimum efficacious dose has not yet been identified. The study design aims to 
provide patients with maximal benefit from axatilimab and reduced unnecessary risk, by 
monitoring all potential risks and incorporating early stopping rules for futility and safety.  
Given the underlying scientific basis for testing CSF-1R targeted therapy in cGVHD, the lack of 
treatment options in this cGVHD population, a study design which includes interim evaluation of 
doses for safety and futility and preliminary PK, pharmacodynamics, safety and evidence of 
clinical activity seen in the ongoing study SNDX-6352-0503, the risk of axatilimab in the 
proposed patient population is justified.  

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3.
OBJECTIVES AND ENDPOINTS
Objectives
Endpoints
Primary
To evaluate the overall 
response rate (ORR) of 
axatilimab at 0.3 mg/kg IV 
Q2W, 1 mg/kg IV Q2W, and 
3 mg/kg IV Q4W in patients 
with cGVHD after failure of 
least 2 prior lines of therapy. 
 
ORR in the first 6 cycles as defined by the 2014 NIH 
Consensus Development Project on Criteria for Clinical 
Trials in cGVHD. 
Key Secondary – Efficacy 
To evaluate key secondary 
measures of clinical benefit 
Proportion of patients with a clinically significant
improvement in modified Lee Symptom Scale score (mLSS). 
Secondary – Efficacy  
 
To evaluate secondary 
measures of clinical benefit. 
 
ORR on study as defined by the 2014 NIH Consensus 
Development Project on Criteria for Clinical Trials in 
cGVHD. 
 
DOR defined as the time from initial response of PR or CR 
until documented progression of cGVHD, start of new 
therapy, or death for any reason. 
 
Sustained response rate (SRR) 
 
Organ-specific response rate based on 2014 NIH Consensus 
Development Project on Criteria for Clinical Trials in 
cGVHD  
 
Joints and fascia response rate based on refined NIH response 
algorithm for cGVHD (Inamoto 2020) 
 
Percent reduction in average daily dose (or equivalent) of 
corticosteroids  
 
Proportion of patients who discontinue corticosteroid use 
after study entry. 
 
Percent reduction in average daily dose (or equivalent) of 
calcineurin inhibitors  
 
Proportion of patients who discontinue calcineurin inhibitors 
use after study entry 

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Objectives 
Endpoints 
Secondary – Safety 
 
To evaluate the safety and 
tolerability of axatilimab in 
patients with cGVHD 
Frequency and severity of AEs and serious adverse events 
(SAEs) 
 
Change from baseline in values for vital signs, safety 
laboratory parameters, physical and neurological 
examination, ECG and Karnofsky/Lansky performance scale 
Secondary – PK/Pharmacodynamic
To assess the plasma 
population PK (pop PK) 
profile of axatilimab in 
patients with cGVHD 
Axatilimab PK parameters and patient factors that may 
explain variability in drug exposure 
 
To assess pharmacodynamic 
profile of axatilimab 
 
Change from baseline in colony stimulating factor 1 (CSF-1), 
interleukin 34 (IL-34) levels and its association with cGVHD 
response 
 
To determine or assess the 
changes in monocyte level 
with response 
 
Change from baseline in circulating monocyte number and 
phenotype (CD14/16) 
 
To determine or assess the 
baseline in monocyte level 
with response 
 
Baseline circulating monocyte number and phenotype 
(CD14/16) 
Secondary – Immunogenicity 

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Objectives 
Endpoints 
Exploratory – Efficacy 
 
To explore possible additional 
evidence of clinical benefit. 
 
 
 
Proportion of patients with Failure Free Survival (FFS) at 
Cycle 7 Day 1 and 1 year. FFS is defined as the time from 
randomization to addition of another systemic immune 
suppressive therapy for cGVHD, relapse of underlying 
malignancy, or death whichever is earlier. 
 
Overall survival (OS) 

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4.
STUDY DESIGN
4.1.
Overall Study Design
AGAVE-201 is a Phase 2, open-label, randomized, multicenter study to evaluate the efficacy, 
safety and tolerability of axatilimab at 3 different dose levels, in patients with recurrent or 
refractory active cGVHD who have received at least 2 prior lines of systemic therapy due to 
progression of disease, intolerability or toxicity. Disease progression is defined 1) by the NIH 
2014 consensus criteria, either in terms of organ specific algorithm or global assessment or, 2) as 
active, symptomatic cGVHD for whom the physician believes that a new line of systemic 
therapy is required.
The study will consist of 3 periods: Screening, Treatment, and Follow-up. Throughout the study, 
patients will be evaluated as specified in the Schedule of Activities (SoA) (Section 1.2).  
After signing informed consent, potential candidates will undergo screening procedures to 
determine eligibility. At enrollment, eligible patients will be randomized to one of 3 dose cohorts 
(axatilimab 0.3 mg/kg IV every 2 weeks [Q2W], 1 mg/kg IV Q2W, or 3 mg/kg IV Q4W). 
Patients must begin treatment (Cycle 1 Day 1) within 3 days of randomization/enrollment and 
will receive axatilimab from Cycle 1 Day 1, in 4-week (28-day) treatment cycles, until disease 
progression (as defined by the NIH 2014 consensus criteria), lack of efficacy by 9 months 
(Section 6.7.2), withdrawal of consent, or unacceptable toxicity. Following treatment 
discontinuation, patients will receive an End of Treatment (EOT) visit 30 days after the last dose 
of study drug and 2 further safety and disease evaluation visits at 60 and 90 days post last dose of 
study drug. 
Simon’s optimal 2-stage design will be implemented within each dose cohort. In the first stage 
27 patients will be randomized to each of the 3 dose cohorts. To limit the potential exposure of 
patients to an inefficacious dose and obviate the need for a pause in accrual, the initial futility 
analysis will be based on an early endpoint (ie, overall response in the first 3 cycles). Each dose 
will be evaluated for futility and unacceptable toxicity as follows: 
 IA #1: Futility assessment based on responses in the first 3 cycleswill be conducted. 
This assessment will occur when the first 27 patients in each cohort have had the 
first 3 cycles of axatilimab (up to and including cycle 4, day 1 assessment), the 
randomization to this dose level may be stopped for futility. Safety assessment will 
first 27 patients having a toxic event defined as any s
 3) 
TEAE that is attributed to study drug. Grade 2 events that are considered treatment-
related and result in medical intervention or hospitalization will be counted as a toxic 
event. 
 IA #2: IA #2 will consist of an overall evaluation of available clinical data. It will be 
conducted when the first 27 patients in each cohort have had the opportunity to 
randomization to this dose level will be stopped for futility. For IA#2, given the full 
enrollment of the study as of this amendment, the rate of toxicity events will be 
provided for all treated patients and will be reviewed as part of the overall benefit/risk 

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assessment. For the overall benefit/risk assessment, a comprehensive safety and 
efficacy analysis will be provided to the IDMC: 
Safety for all participants. 
 Efficacy for all participants who have had the opportunity to receive 3 cycles of 
axatilimab. 
Study randomization will not pause while data from the interim analyses are being evaluated. 
An Independent Data Monitoring Committee will evaluate all data that are available at the time 
of the data cut for the interim analyses, and provide a recommendation on continued use of the 
available axatilimab dose levels.  
A final efficacy analysis will be performed when all patients have had the opportunity to 
patients have had a response to axatilimab (PR or CR), as defined by NIH 2014 cGVHD criteria. 
The final boundary for efficacy will be re-calculated if there is over enrollment in the second 
stage of the design. For example, if the total number of randomized patients in a dose level is 80, 
e had a response to axatilimab.  
At the final analysis, if 19 or more patients out of the total 70 patients experience a toxic event 
(the boundary will be recalculated if there is over enrollment), this will indicate a 90% posterior 
probability of the toxicity rate exceeding 20% and the final determination of acceptability of a 
given dose will be based on the overall benefit/risk indicated by review of the totality of 
evidence.  
Patients enrolled into a Q2W regimen may be eligible to change to a Q4W dosing during the 
study, as described in Section 6.3. Additional dosing modifications for already enrolled patients 
may be implemented following IDMC recommendation on closing enrollment to one or more 
dose level cohorts and are specified in Section 6.2.1.  
The on-treatment response criteria will be assessed every 4 weeks and at the EOT visit or 
discontinuation of the study intervention using 2014 NIH Consensus Development Project on 
Criteria for Clinical Trials in cGVHD: CR, PR, lack of response (unchanged, mixed or 
progression). 
4.2. 
Dose Justification 
The doses selected for this Phase 2 study of axatilimab in patients with cGVHD are 0.3 mg/kg IV 
Q2W, 1 mg/kg IV Q2W, and 3 mg/kg IV Q4W. 

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4.3.
Rationale for Study Design
This randomized, Phase 2 study is designed to further evaluate axatilimab at 3 dose levels 
(0.3 mg/kg IV Q2W, 1 mg/kg IV Q2W and 3 mg/kg IV Q4W) in patients with cGVHD. 
 
 
  
This study is designed to reflect standard Phase 2 studies evaluating investigational agents in 
patients with cGVHD, at each of the dose levels selected. It incorporates interim analyses to limit 
patients’ exposure to doses that do not provide sufficient efficacy or acceptable toxicity. The 
primary endpoint, ORR by Day 169 or Cycle 7, Day 1 (whichever is later), has been selected 
based on its use in other cGVHD studies and its apparent correlation with overall survival 
(Jagasia 2018, Jagasia 2019).  
Based on data from SNDX-6352-0503, evaluation of axatilimab at the 3 selected dose levels to 
identify a minimum efficacious axatilimab dose or maximum acceptable dose is warranted. 
Furthermore, the primary endpoint selected for the study will enable robust evaluation of the 
efficacy data from patients dosed at the selected dose level(s). This approach will enable 
thoughtful development of axatilimab in an orphan population of high unmet medical need.

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4.4.
End of Study Definition
There will be 3 dosing arms: 0.3 mg/kg IV Q2W, 1 mg/kg IV Q2W, and 3 mg/kg IV Q4W. Total 
study duration for each patient will be up to 28 months (excluding survival follow-up) as 
follows: 
Screening period:  
Up to 28 days (1 month) prior to the first dose of study 
intervention 
Treatment period: 
Until unequivocal disease progression or unacceptable 
toxicity up to a maximum period of 2 years. Patients who 
continue to derive benefit after 2 years of treatment, 
administration may continue following consultation with 
sponsor. 
Safety Follow-up period:  
Up to 90 days (3 months) after the last administration of 
study intervention 
Overall survival follow-up 
period:
After completing safety follow-up, patients will be contacted 
every 3 months to assess overall survival for up to 5 years.
End of Study:
The final contact with the last patient for survival follow-up.

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5.
STUDY POPULATION
5.1.
Inclusion Criteria
To be eligible for participation in this study, participants must meet all the following: 
Age
1. Patient must be 2 years of age or older, at the time of signing the informed consent. 
Type of Participant and Disease Characteristics 
2. Patients who are allogeneic HSCT recipients with active cGVHD requiring systemic 
immune suppression. 
Active cGVHD is defined as the presence of signs and symptoms of cGVHD per 2014 
NIH Consensus Development Project on Criteria for Clinical trials in cGVHD (Jagasia 
2015).  
3. Patients with refractory or recurrent active cGVHD despite at least 2 lines of systemic 
therapy.
 Refractory disease defined as meeting any of the following criteria:
- The development of 1 or more new sites of disease while being treated for 
cGVHD. 
- Progression of existing sites of disease despite at least 1 month of standard or 
investigation therapy for cGVHD. 
- Patients who have not achieved a response within 3 months on their prior therapy 
for cGVHD and for whom the treating physician believes a new systemic therapy 
is required. 
 Recurrent cGVHD is active, symptomatic disease (after an initial response to prior 
therapy) as defined, based on the NIH 2014 consensus criteria, by organ-specific or 
global assessment or for which the physician believes that a new line of systemic 
therapy is required.  
4. Patients may have persistent, active acute and cGVHD manifestations (overlap 
syndrome), as defined by 2014 NIH Consensus Development Project on Criteria for 
Clinical trials in cGVHD. 
Diagnostic Assessments 
5. 
6. Adequate organ and bone marrow functions evaluated during the 14 days prior to 
randomization as follows: 
 
× 109/L (without growth factors within 1 week of 
study entry)
 
 × 109/L (without growth factor or transfusion within 2 weeks of 
study entry)
 ALT and AST  2.5 × upper limit of normal (ULN) and total bilirubin 
. 

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 × ULN 
7. 
-Gault formula in adult 
patients and Schwartz formula in pediatric patients. 
Sex
8. Male and/or female participants.
Contraceptive use by men or women should be consistent with local regulations 
regarding the methods of contraception for those participating in clinical studies. 
 Adolescent and adult male patients capable of fathering a child who are non-sterilized 
and who are not abstinent and intend to be sexually active with a female partner of 
childbearing potential must use a male condom plus spermicide from the time of
screening throughout the total duration of the study intervention treatment period and 
90 days after the last dose of study intervention. However, periodic abstinence, the 
rhythm method, and the withdrawal method are not acceptable methods of 
contraception. Male patients should refrain from sperm donation throughout this 
period. 
 Female patients, post-menarche, must provide evidence of either post-menopausal 
status or negative urinary or serum pregnancy test. Women will be considered post-
menopausal if they have been amenorrheic for 12 months without an alternative 
medical cause. The following age-specific requirements apply: 
 Menarche, regardless of age, is defined as having had the first occurrence of 
menstruation. 
 Women <50 years of age would be considered post-menopausal if they have been 
amenorrheic for 12 months or more following cessation of exogenous hormonal 
treatments and if they have luteinizing hormone and follicle-stimulating hormone 
levels in the post-menopausal range for the institution or underwent surgical 
sterilization (bilateral oophorectomy or hysterectomy). 
 
-menopausal if they have been 
amenorrheic for 12 months or more following cessation of all exogenous 
hormonal treatments, had radiation-induced menopause with last menses >1 year 
ago, had chemotherapy-induced menopause with last menses >1 year ago, or 
underwent surgical sterilization (bilateral oophorectomy, bilateral salpingectomy 
or hysterectomy). 
 Female patients of childbearing potential who are not abstinent and intend to be 
sexually active with a nonsterilized male partner must use at least 1 highly 
effective method of contraception from 14 days prior to randomization throughout 
the total duration of the study intervention treatment period and 90 days after the 
last dose of study intervention. Non-sterilized male partners of a female patient of 
childbearing potential must use male condom plus spermicide throughout this 
period. Cessation of birth control after this point should be discussed with a 
responsible physician. Periodic abstinence, the rhythm method, and the 

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withdrawal method are not acceptable methods of birth control. Female patients 
should also refrain from breastfeeding throughout this period.
9. Concomitant use a of systemic corticosteroid is allowed but not required. Topical and 
inhaled corticosteroid agents are allowed. If a patient is taking corticosteroids at study 
randomization, the following criteria must be met:  
 Be on a stable dose of corticosteroids for at least 2 weeks prior to Cycle 1 Day 1.  
10. Concomitant use of CNI or mTOR inhibitors (sirolimus or everolimus) is allowed but not 
required. The CNI or mTOR inhibitors may have been started either for prophylaxis or 
for treatment of cGVHD the reason for initiating treatment must be recorded in the 
database). If a patient is taking either a CNI or mTOR inhibitor at study randomization, 
the following criteria must be met:   
 Be on a stable dose of CNI or mTOR inhibitor for at least 2 weeks prior to 
randomization. 
 The dose of the CNI or mTOR inhibitor must be within the therapeutic range. 
Informed Consent 
11. Capable of giving signed informed consent which includes compliance with the 
requirements and restrictions listed in the informed consent form (ICF) and in this 
protocol. A parent/guardian should provide consent for pediatric patients unable to 
provide consent themselves; in addition, where applicable pediatric patients should sign 
their own assent form. 
5.2. 
Exclusion Criteria 
Patients are excluded from the study if any of the following criteria apply: 
Medical Conditions 
1. Has acute GVHD without manifestations of cGVHD.
2. Any evidence (histologic, cytogenetic, molecular, hematologic, or mixed) of relapse of 
the underlying cancer or post-transplant lymphoproliferative disease at the time of 
screening. 
3. History of acute or chronic pancreatitis  
4. History of myositis.
5. History or other evidence of severe illness, uncontrolled infection, allergy to excipients 
(see formulation details in Investigator Brochure), or any other conditions that would 
make the patient, in the opinion of the Investigator, unsuitable for the study. 
6. Patients with acquired immune deficiency syndrome (AIDS).
7. Hepatitis B (defined as hepatitis B virus [HBV] surface antigen positive and HBV core 
antibody positive, with positive HBV deoxyribonucleic acid [DNA], or HBV positive 
core antibody alone with positive HBV DNA. Hepatitis C (defined as positive hepatitis C 
[HCV] antibody with positive HCV ribonucleic acid [RNA]).

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8. Diagnosed with another malignancy (other than malignancy for which transplant was 
performed) within 3 years of randomization, unless previously treated with curative intent 
and approved by Sponsor’s Medical Monitor (eg, completely resected basal cell or 
squamous cell carcinoma of the skin, resected in situ cervical malignancy, resected breast 
ductal carcinoma in situ, or low-risk prostate cancer after curative resection). 
9. Female patient who is pregnant or breastfeeding
Prior/Concomitant Therapy 
10. Previous exposure to CSF-1R–targeted therapies.
11. Taking agents for treatment of cGVHD other than corticosteroids or either a CNI or 
mTOR inhibitor is prohibited. See Inclusion Criteria 9 and 10 for guidelines regarding the 
appropriate use of corticosteroids, CNI, and mTOR inhibitor in combination with study 
treatment. 
12. For approved or commonly used agents, other than corticosteroids, CNI and mTOR 
inhibitor, a washout of 2 weeks or 5 half-lives, whichever is shorter, is required at study 
enrollment. 
Prior/Concurrent Clinical Study Experience 
13. Receiving an investigational treatment within 28 days of randomization. 
Concurrent Studies 
14. Patients should not be participating in any other interventional study. Pediatric patients 
are encouraged to also participate in the ongoing developmental studies of the Pediatric 
cGVHD Symptom Scale (PCSS). 
Additional Medical Conditions
15. Patients with a of history of latent or active tuberculosis (TB) before screening; signs or 
symptoms suggestive of active TB upon medical history and/or physical examination; 
recent close contact with a person with active TB; positive QuantiFeron TB test at 
screening.  
 

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6.
STUDY INTERVENTION
Study intervention is defined as any investigational intervention(s), marketed product(s), 
placebo, or medical device(s) intended to be administered to a study patient according to the 
study protocol.
6.1. 
Study Intervention(s) Administered 
Table 3
Study Intervention 
Intervention Name 
Axatilimab (SNDX-6352) 
Type 
Biologic
Dose Formulation
Solution for infusion
Drug Product 
Strength 
 mg/mL 
Unit Dose Strength(s) 
mg/kg 
Original Dosage 
Level(s) 
0.3 mg/kg IV Q2W, 1 mg/kg IV Q2W (Day 1 and 15 of each 4-week cycle) 
or 3 mg/kg IV Q4W (Day 1 of each 4-week cycle) 
Route of 
Administration 
IV infusion via an infusion pump over 
; time windows of 
 
 are permitted (ie, infusion time is 
). 
The exact duration of infusion should be recorded in both source documents 
and electronic case report forms (eCRFs). 
IMP definition 
A new drug or biological drug that is used in a clinical investigation (FDA). 
Sourcing 
Study intervention will be provided to the site centrally by the Sponsor or 
designated representative. 
Packaging and 
Labeling 
Axatilimab is supplied as a 
 sterile, 
preservative free solution in 
, colorless, 
 closed with a 
rubber stopper and sealed with an aluminum overseal and flip-off cap. The 
 are single use only and contain no preservatives. 
Label text for the axatilimab vial will at a minimum include the protocol 
number, the contents of the vial (eg, axatilimab 
 mg/mL), lot number, 
storage conditions, and Sponsor name and address. Labels comply with 
regulatory requirements for investigational products. 
Former Name(s) or 
Alias(es) 
UCB-6352, SNDX-6352 
6.2. 
Intrapatient Dose Escalation  
Intrapatient dose escalation is not permitted. Dose adjustment(s) related to change in dosing 
schedule (Section 6.3.) are not considered dose escalations as the dose intensity remains 
unchanged.

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6.3. 
Changes to Dosing Schedule 
Patients enrolled into Q2W regimens may have their dosing regimens changed to Q4W if they 
meet the criteria provided in Section 6.3.1, 6.3.2 or 6.3.3. Changes to dosing schedule are not 
considered dose escalations as the dose intensity remains unchanged.
If, following a change in schedule from Q2W to Q4W, a patient progresses, they may return to a 
Q2W schedule. At the time of change from a Q2W to Q4W schedule and vice versa, the dose 
intensity must remain the same (ie, the dose intensity immediately before the change must equate 
to the dose intensity immediately after the change). 
6.3.1.
Patients Enrolled into the 1 mg/kg IV Q2W Dose Schedule
Patients who have had their Cycle 7 assessment and have achieved a PR/CR that has been 
sustained for at least 20 weeks or have not progressed may change their dose schedule from 
Q2W to Q4W. 
6.3.2.
Patients Enrolled into the 0.3 mg/kg IV Q2W Dose Schedule
Patients who have had their Cycle 7 assessment and have achieved a PR/CR that has been 
sustained for at least 20 weeks or have not progressed may change their dose schedule from 
Q2W to Q4W. 

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6.3.3.
Patients Who Have Escalated to the 1 mg/kg IV Q2W Dose Schedule from 
0.3 mg/kg Q2W
If a patient has experienced a PR/CR or has not progressed following dose escalation to 1 mg/kg 
IV Q2W (Section 6.2) and their best response is maintained for 20 weeks, they may change their 
dose schedule from Q2W to Q4W. 
 
6.3.4. 
Patients Who Have Previously Dose Reduced for Reasons of Toxicity
Patients who have previously dose reduced for a reason of toxicity, have had their Cycle 7 
assessment, and have achieved a PR/CR that has been sustained for at least 20 weeks or have not 
progressed may change their dose schedule from Q2W to Q4W. 
 
6.4.
Randomization to Axatilimab Dose Level
All patients will be centrally assigned to axatilimab dose in a 1:1:1 randomization ratio using an 
Interactive Response Technology (IRT). Patient assignments will be stratified for severity of 
cGVHD (mild/moderate vs. severe) by the 4-point scale and prior use of at least one of the 
following therapies: ibrutinib, ruxolitinib and belumosudil (prior therapy vs. no prior therapy). 
Before the study is initiated, the log-in information and directions for the IRT will be provided to 
each site. This study will be an open-label study.
6.5. 
Preparation/Handling/Storage/Accountability 
1. The Investigator or designee must confirm appropriate temperature conditions have been 
maintained during transit for all study intervention received and any discrepancies are 
reported and resolved before use of the study intervention. 
2. Only patients enrolled in the study may receive study intervention and only authorized 
site staff may supply or administer study intervention. All study intervention must be 
stored in a secure, environmentally controlled, and monitored (manual or automated) area 
in accordance with the labeled storage conditions with access limited to the Investigator 
and authorized site staff.
3. SNDX-6352 drug product must be diluted to 
 
 supplied in an infusion bag. No other drugs should be added to the 
solution for infusion containing SNDX-6352. 
4. The dose amount required to prepare the SNDX-6352 infusion solution will be based on 
the patient’s weight in kilograms (kg). All patients should be weighed within 3 days prior 
to dosing. If the patient experiences either a weight loss or gain >10% compared to the 
weight used for the last dose calculation, the amount of study intervention must be 
recalculated. For weight change <10%, the decision to recalculate the SNDX-6352 dose 
can be in accordance with institutional practice. There is no dose cap or need for adjusted 
weight when calculating the dose for patients with a high BMI.

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5. The solution for infusion should be used immediately to limit microbial growth in case of 
potential accidental contamination. If not used immediately, the solution can be stored at 
room temperature for a maximum of 4 hours.  
6. Drug should be administered via an infusion pump.
7. The Investigator, institution, or the head of the medical institution (where applicable) is 
responsible for study intervention accountability, reconciliation, and record maintenance 
(ie, receipt, reconciliation, and final disposition records). 
8. Further guidance and information for the final disposition of unused study interventions 
are provided in the Pharmacy Manual. 
6.6.
Study Intervention Compliance
Administration of axatilimab will be supervised by the Investigator or sub-Investigator. Any 
delegation of this responsibility must follow the standard procedures. Records of treatment 
administration for each patient will be kept during the study. Clinical research associates will 
review study intervention administration records and verify compliance with the Pharmacy 
Manual during site visits and at the completion of the study. Deviation(s) from the prescribed 
dosage regimen should be recorded in the eCRF.
For the first 2 axatilimab infusions, a mandatory 2-hour observation period for potential 
infusion-related reactions is required. For subsequent infusions and per the discretion of the 
investigator, patients who have had no infusion reactions may be observed for a shorter period of 
at least 30 minutes. Patients who experience an infusion-related reaction at any time, must 
continue to undergo the mandatory 2-hour observation period after each infusion. 
6.7. 
Stopping Rules and Dose Modifications 
Dose delays and dose reductions (Table 4) will be allowed as described in Section 6.7.1. Patients 
who do not tolerate therapy after 2 dose level reductions from starting dose must withdraw from 
the study. Once the axatilimab dose has been reduced for reasons of toxicity, it cannot be 
re-escalated, however the dose schedule may be adjusted as provided in Section 6.3.4. Dose 
interruptions for reason(s) other than toxicity, such as surgical procedures, may be allowed with 
Sponsor approval. The acceptable length of interruption will depend on agreement between the 
Investigator and the Sponsor.
All dose modifications should be documented appropriately. Investigators may take a more 
conservative approach than the guidelines outlined in the protocol if, based on their clinical 
judgment, that is in the best interest of the patient. Such instances should be reported to the 
Sponsor’s Medical Monitor. 

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6.7.1.
Guidelines for Toxicity Management
The guidelines for the management of toxicities are outlined as follows with each toxicity graded 
by the Investigator according to the NCI CTCAE, version 5.0. 

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6.7.1.2. 
Other Non-hematologic Toxicity  
The rules for the management of other non-hematologic toxicities are outlined as follows in 
Table 6 with toxicities graded by the Investigator according to the NCI CTCAE, version 5.0. 
Table 6
Other Non-hematologic Toxicity: Dose Modification Guidelines for 
Axatilimab
Toxicity 
Dose modifications 
Grade 4 
Administer symptomatic remedies/start prophylaxis. 
Any Grade 4 events require permanent treatment discontinuation from 
axatilimab. 
Grade 3 
Administer symptomatic remedies/start prophylaxis. Hold axatilimab 
dose until recovery to Grade 2 under the following directions: 
1. 
axatilimab at the 
next lower dose (Table 4). 
2. If the axatilimab dose is held for more than 4 weeks, 
permanently discontinue axatilimab. 
Grade 2 
Administer symptomatic remedies/start prophylaxis. 
Do not hold axatilimab dose. 
Note: Grade is per CTCAE 5.0 
6.7.1.3. 
Hematologic Toxicity  
The guidelines in Table 7 will be followed for determining the dose modifications based on 
hematologic status at the time of planned dosing. 

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Table 7 
Hematologic Toxicity: Dose Modification Guidelines for Axatilimab 
Toxicity
Dose Modifications
Grade 3 to 4 neutropenia, 
Febrile neutropenia or 
neutropenic infection 
Grade 3 to 4 
uncomplicated 
thrombocytopenia, or 
Grade 2 complicated 
thrombocytopenia 
Hold axatilimab dose until recovery to Grade 1 or study baseline under the 
following directions. 
1. 
lower dose (Table 4).  
2. If the axatilimab dose is held for more than 4 weeks, permanently 
discontinue axatilimab. 
Recurrence of the same 
hematologic toxicity
If the same hematologic toxicity recurs: 
1. Administer symptomatic remedies/start prophylaxis. Hold 
axatilimab dose until recovery to Grade 1 or baseline. 
2. If recovered within 7 days, resume axatilimab at next lower dose 
(Table 4). 
3. If the episode is not recovered within 14 days despite axatilimab 
dose reduction to next lower dose, as described above, 
permanently discontinue axatilimab. 
4. If the 3rd episode, permanently discontinue axatilimab. 
Note: Grade is per CTCAE 5.0 
6.7.1.4. 
Axatilimab Infusion-Related Reaction
Monitor patients for signs and symptoms of infusion-related reactions (eg, fever and/or shaking 
chills, flushing and/or itching, alterations in heart rate and blood pressure, dyspnea or chest 
discomfort, or skin rashes) and anaphylaxis (eg, generalized urticaria, angioedema, wheezing, 
hypotension, or tachycardia).  
Patients experiencing an infusion-related reaction should be managed per institutional standard 
of care. Treatment recommendations for axatilimab infusion-related reactions are outlined in 
Table 8.
If a patient experiences an axatilimab infusion-related reaction, they may continue on study 
intervention treatment per guidance presented in Table 8. Patients who previously experienced 
an infusion-related reaction will receive a premedication regimen of 25 to 50 mg IV or oral 
equivalent diphenhydramine and acetaminophen/paracetamol (dosed per institutional guidelines) 
approximately 30 to 60 minutes prior to each subsequent dose of axatilimab. Prophylactic 
administration in the absence of prior infusion-related reaction is permitted as described in 
Section 6.9. Prophylactic corticosteroids are not permitted. 

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Table 8 
Guidance for Treatment of Infusion-related Reactions  
NCI-CTCAE 
Grade 
Dose Modification 
Toxicity Management 
Grade 1 or 2
For Grade 1:
The infusion rate of study 
drug/study regimen should be 
decreased by 50% or temporarily 
interrupted until resolution of the 
event. 
For Grade 2: 
The infusion rate of study 
drug/study regimen should be 
decreased 50% or temporarily 
interrupted until resolution of the 
event. Subsequent infusions should 
be given at 50% of the initial 
infusion rate. 
For Grade 1 or 2: 
 
Acetaminophen and/or antihistamines 
may be administered per institutional 
standard at the discretion of the 
investigator. 
 
Consider premedication per institutional 
standard prior to subsequent doses. 
 
Steroids should not be used for routine 
reactions. 
Grade 3 or 4  
For Grade 3 or 4: 
Permanently discontinue study 
drug/study regimen 
For Grade 3 or 4: 
 
Manage severe infusion-related reactions 
per institutional standards (eg, IM 
epinephrine, followed by IV 
diphenhydramine and ranitidine, and IV 
glucocorticoid). 
CTCAE Common Terminology Criteria for Adverse Events; IM intramuscular; IV intravenous; NCI National 
Cancer Institute 
Note: Grade is per CTCAE 5.0
If a Grade 2 infusion-related reaction does not improve or worsens after implementation of the 
modifications indicated in Table 8 (including reducing the infusion rate by 50%), the Investigator 
may consider treatment with corticosteroids, and the infusion should be stopped for that day. At 
the next cycle, administration of oral premedication with antihistamine and anti-pyretic is 
required. Prophylactic steroids are NOT permitted. If the patient has a second infusion-related 
reaction of Grade 2 or higher on the slower 50% infusion rate, with or without the addition of 
further medication to the mandatory premedication, the infusion should be stopped, and the 
patient removed from axatilimab treatment.
6.7.2.
Discontinuation of Study Treatment for Lack of Efficacy
Study treatment should be discontinued if a patient does not achieve a PR within 9 months of 
initiating therapy. However, a patient may continue on study treatment if the PI/treating 
physician believes that the patient is deriving clinical benefit AND if the patient reports clinically 
meaningful symptomatic improvement (that may not be captured by the NIH criteria).  
Any patient dosed at 0.3 mg/kg Q2W, 1 mg/kg Q2W or 3 mg/kg Q4W (or per dose adjustments) 
who experiences an unequivocal progression of cGVHD (initiation of new systemic therapy for 
cGVHD; increase in corticosteroid and/or CNI/mTOR inhibitor dose beyond those allowed by 
protocol) at any time should have their treatment discontinued.  

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6.8.
Rescue Medications and Supportive Care
Participants should receive appropriate supportive care measures as deemed necessary by the 
treating Investigator.  
6.9. 
Concomitant Medication 
Any medication or vaccine (including over the counter or prescription medicines, vitamins, 
and/or herbal supplements) that the patient is receiving within 28 days of randomization or 
receives during the study must be recorded along with:
 Reason for use 
 Dates of administration including start and end dates. 
Dosage information including dose and frequency.
Vaccines, other than live vaccines, which are prohibited (Section 6.9.2), should be taken on a 
week when the axatilimab infusion is not administered.
Biologic therapies (intravenous immunoglobulins, monoclonal antibodies) used for non-
antineoplastic and non-cGVHD causes are permitted. However, they should be administered on a 
week when the axatilimab infusion is not given.  
Topical therapies (including topical corticosteroids) that the Investigator considers necessary for 
a patient’s plan of care may be administered concomitantly with axatilimab at the Investigator’s 
discretion per standard of care. Other supportive medications in accordance with standard 
clinical practice (such as for prophylaxis for encapsulated bacteria, viral, or fungal infections) are 
permitted per institutional policy. 
Premedication with 25 to 50 mg IV or oral equivalent diphenhydramine and 
acetaminophen/paracetamol approximately 30 to 60 minutes prior to each dose of axatilimab 
may be administered in accordance with standard site practice in the absence of prior infusion 
related reactions. Use of corticosteroids for infusion reaction prophylaxis is not permitted. 
Use of systemic corticosteroids to treat acute non cGVHD conditions eg, anaphylaxis, adrenal 
crisis, etc. is allowed as clinically indicated, provided that the steroid dose can be tapered to 
baseline within 14 days. 
The Medical Monitor should be contacted if there are any questions regarding concomitant or 
prior therapy.  
6.9.1. 
Corticosteroids, CNI and mTOR inhibitors 
Adjustments to concomitant medications such as corticosteroids and/or CNI/mTOR inhibitors 
should be made as follows:   
6.9.1.1. 
Corticosteroids 
Patients may be taking a corticosteroid on study entry. The dose of corticosteroids may be 
tapered after the first 4 weeks of study intervention administration in patients who have achieved 
either a PR or CR, at the discretion of the Investigator. However, it is strongly recommended that 

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they are tapered at a rate of no more than 25% of the daily dose every 4 weeks and that they are 
tapered prior to discontinuation of any concomitant CNI or sirolimus. 
For patients whose steroid dose has been tapered, one re-escalation of corticosteroids (up to 
starting dose) is allowed at the discretion of Investigator, up to 6 months from start of axatilimab.  
In the case of exacerbation of cGVHD, patients may have one increase in corticosteroid dose of 
up to a maximum total daily dose of 0.9 mg/kg prednisone dose equivalent for a period of no 
longer than 8 weeks.
6.9.1.2. 
CNI or mTOR inhibitors
Patients may be taking a CNI or an mTOR inhibitor (sirolimus or everolimus) on study entry. 
The dose on Cycle 1 Day 1 must have been stable for at least 2 weeks (Inclusion Criterion 9). 
After the first post-baseline assessment a patient’s CNI or mTOR inhibitor dose may be adjusted. 
Reasons for adjustment are as follows:
 To maintain a therapeutic dose - in this case the CNI or mTOR inhibitor dose may be 
increased above the dose at Cycle 1 Day 1.  
 For a cGVHD flare – in this case the dose of CNI or mTOR inhibitor may be increased 
once above the dose at Cycle 1 Day 1.  
 If patient is receiving a fixed dose of a CNI or an mTOR inhibitor and a new medication 
is started that significantly changes their metabolism. In such case, dose adjustment may 
be pursued following established evidence (eg, decrease in tacrolimus dose by 1/3 upon 
initiation of voriconazole). Reason for this change must be documented in the eCRF
A substitute CNI or mTOR inhibitor cannot be started unless change is indicated by toxicity or 
intolerance of previously used agent; reason for this change must be documented in the eCRF. 
If after 4 weeks of study intervention the patient achieves a PR or CR, the dose of CNI or mTOR 
inhibitor may be reduced or discontinued; for such cases, doses may be increased subsequently 
for flare of cGVHD to no more than the dose at Cycle 1 Day 1. At the discretion of the treating 
physician and aligned with institutional policy, whenever possible it is recommended that the 
concomitant CNI or mTOR inhibitor be tapered after tapering of any concurrent corticosteroid.   
6.9.2. 
Prohibited Medications
 Except for systemic corticosteroid, an mTOR inhibitor or a CNI, any other immune 
suppressive agents for treatment of chronic GVHD are not permitted. 
 This does not include agents for treatment of acute GVHD or the acute 
manifestations of overlap syndrome. 
 Live virus vaccinations 
 Antineoplastic systemic chemotherapy or biological therapy.
Concomitant use of medications indicated for maintenance therapy targeting the 
patient’s previously treated underlying malignancy is allowed, including but not 

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limited to the use of proteasome inhibitors (e.g. ixazomib), endocrine therapies 
(e.g. tamoxifen, exemestane), and tyrosine kinase inhibitors (e.g. sorafenib, 
imatinib).
 Investigational agents other than axatilimab 
 Radiation therapy 
 Traditional herbal medicines: these therapies are not fully studied, and it is unknown 
whether their use may result in unanticipated drug-drug-interactions that may cause or 
confound the assessment of toxicity 

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7.
DISCONTINUATION OF STUDY DRUG AND PATIENT 
DISCONTINUATION/WITHDRAWAL 
7.1. 
Discontinuation of Study Drug 
It may be necessary for a patient to permanently discontinue study intervention prior to planned 
completion of treatment regimen (see Section 6.7 for dose modification and toxicity 
management). If study intervention is permanently discontinued, the patient will remain in the 
study to be evaluated for up to 90 days post last dose of study intervention. See the Schedule of 
Activities (Section 1.2) for data to be collected at the time of discontinuation of study 
intervention (30 days post last dose of study intervention). 
7.2. 
Patient Discontinuation/Withdrawal from the Study 
Patients have the right to withdraw partially or fully from the study at any time and for any 
reason without prejudice to their future medical care by the physician or at the institution. 
Partial withdrawal of consent means that the patient does not wish to take study intervention any 
longer but is still willing to collaborate in providing further data by continuing on study (eg, 
participate in all subsequent study visits or procedures or follow-up contact). Full withdrawal of 
consent for a study means that the patient does not wish to receive further investigational 
treatment and does not wish to, or is unable to, continue further study participation. Any patient 
may fully or partially withdraw consent to participate in the study at any time during the study. 
The level of study withdrawal is to be noted in the source documentation.
In the event of discontinuation of all treatment or full withdrawal from the study, the Investigator 
will complete the End of Treatment form and indicate the date and the appropriate reason. To the 
greatest extent possible, the Investigator will attempt to complete all protocol-required tests and 
evaluations listed for the End of Treatment visit, Safety Follow-up visits, and Overall Survival 
Follow-up. If a patient fails to return for the necessary visits, every effort must be made to 
contact the patient and determine the reason(s); this should be recorded on the eCRF. 
Reasons for permanently discontinuing study therapy and/or observation might include: 
 Withdrawal of consent 
 Progressive disease or exacerbation of any of the signs or symptoms of the disease 
assessed by Investigator. 
Administrative decision by the Investigator or Sponsor. 
Pregnancy 
Significant protocol deviation or patient noncompliance. 
 Unacceptable toxicity 
 A study treatment delay >4 weeks due to AEs. 
 Need for intervention or therapy determined by the Investigator to be medically 
necessary that is precluded by protocol. 

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 The Investigator believes it is no longer in the patient’s best interest to continue study 
therapy. 
In addition, the Sponsor may decide to discontinue the trial prematurely for any reason. 
7.3. 
Lost to Follow up 
A patient will be considered lost to follow-up if he or she repeatedly fails to return for scheduled 
visits and is unable to be contacted by the study site. 
The following actions must be taken if a patient fails to return to the clinic for a required study 
visit:
 The site must attempt to contact the patient and reschedule the missed visit as soon as 
possible and counsel the patient on the importance of maintaining the assigned visit 
schedule and ascertain whether or not the patient wishes to and/or should continue in 
the study. 
 Before a patient is deemed lost to follow up, the Investigator or designee must make 
every effort to regain contact with the patient (where possible, 3 telephone calls and, if 
necessary, a certified letter to the patient’s last known mailing address or local 
equivalent methods). These contact attempts should be documented in the patient’s 
medical record. 
 Should the patient continue to be unreachable, he/she will be considered to have 
withdrawn from the study. 
Discontinuation of specific sites or of the study as a whole are handled as part of Appendix 1 in 
Section 10.1. 

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8.
STUDY ASSESSMENTS
Planned timepoints for all study assessments are provided in the SoA (Table 1) and the PK and 
pharmacodynamic sample collection table (Table 2). Details required to carry out each 
assessment in addition to what is provided in the SoA, Sample Collection table and the footnotes 
is provided in the sections below. 
8.1.
Efficacy Assessments
It is preferred that all cGVHD assessments be done by the same health care provider who 
completed the C1D1 assessment. At minimum, the C7D1 assessment should be performed by the 
same health care provider who performed the C1D1 assessment. In addition, any assessments 
leading to changes in cGVHD therapy must be confirmed by the PI or primary treating 
physician. 
8.1.1. 
Response Determination according to 2014 NIH Consensus definitions 
Overall physician-assessed responses will be evaluated as defined by the 2014 NIH Consensus 
Development Project on Criteria for Clinical trials in cGVHD (Lee 2015). CR is defined as 
resolution of all manifestations in each organ or site, and PR is defined as improvement in at 
least 1 organ or site without progression in any other organ or site. Table 9 contains the Working 
Group proposed consensus definitions of CR, PR and progression for assessment of organ- 
specific responses as well as a global response determination. 
Table 9
Response Determination for Chronic GVHD Clinical Studies based on 
Clinician Assessments
Organ 
Complete Response 
Partial Response 
Progression 
Skin 
NIH Skin Score 0 after 
previous involvement 
Decrease in NIH Skin Score 
by 1 or more points 
Increase in NIH Skin Score 
by 1 or more points, except 
0 to 1 
Eyes 
NIH Eye Score 0 after 
previous involvement 
Decrease in NIH Eye Score 
by 1 or more points 
Increase in NIH Eye Score 
by 1 or more points, except 
0 to 1 
Mouth 
NIH Modified OMRS 0 
after previous involvement 
Decrease in NIH Modified 
OMRS of 2 or more points 
Increase in NIH Modified 
OMRS of 2 or more points 
Esophagus 
NIH Esophagus Score 0 
after previous involvement 
Decrease in NIH Esophagus 
Score by 1 or more points 
Increase in NIH Esophagus 
Score by 1 or more points, 
except 0 to 1 
Upper GI 
NIH Upper GI Score 0 
after previous involvement 
Decrease in NIH Upper GI
Score by 1 or more points 
Increase in NIH Upper GI 
Score by 1 or more points, 
except 0 to 1 
Lower GI 
NIH Lower GI Score 0 
after previous involvement 
Decrease in NIH Lower GI 
Score by 1 or more points 
Increase in NIH Lower GI 
Score by 1 or more points, 
except from 0 to 1 

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Organ
Complete Response
Partial Response
Progression
Liver 
Normal ALT, alkaline 
phosphatase, and total 
bilirubin after previous 
elevation of 1 or more 
Decrease by 50% 
Increase by 2 × ULN
Lungs 
Normal %FEV1 after 
previous involvement
If PFTs not available, NIH 
Lung Symptom Score 0 
after previous involvement 
Increase by 10% predicted 
absolute value of %FEV1
If PFTs not available, 
decrease in NIH Lung 
Symptom Score by 1 or 
more points 
Decrease by 10% predicted 
absolute value of %FEV1
If PFTs not available, 
increase in NIH Lung 
Symptom Score by 1 or 
more points, except 0 to 1 
Joints and 
fascia 
Both NIH Joint and Fascia
Score 0 and P-ROM score 
25 after previous 
involvement by at least 1 
measure 
Decrease in NIH Joint and 
Fascia Score by 1 or more 
points or increase in P-ROM 
score by 1 point for any site 
Increase in NIH Joint and 
Fascia Score by 1 or more 
points or decrease in P-
ROM score by 1 point for 
any site 
Global 
Clinician overall severity 
score 0 
Clinician overall severity 
score decreases by 2 or 
more points on a 0-10 scale 
Clinician overall severity 
score increases by 2 or more 
points on a 0-10 scale 
Source: Lee, 2015. 
8.1.2. 
Response Determination for Pediatric Patients 
No special assessments will be performed for pediatric patients. However, for younger patients, 
or those unable to comply, PFT assessments will include pulse oximetry and as clinically 
indicated, CT scan with inspiratory and expiratory phases to assess air trapping. 
8.1.3. 
Physician-Reported Global and Organ Specific cGVHD Activity Assessment 
Changes in cGVHD severity as defined by the NIH 2014 Consensus Criteria will be evaluated 
using physician reported global and organ-specific cGVHD activity assessment form 
(Section 10.5). The clinicians will provide a subjective assessment of current overall chronic 
GVHD severity on a 10-point category scale (no chronic GVHD, mild, moderate, severe)
independent of the recorded NIH global severity score (Table 9, last line), and their evaluations 
of cGVHD changes since the last assessment. Key organ assessments include skin, mouth, liver, 
upper and lower GI, esophagus, lung, eye, and joint/fascia (Jagasia 2015, Lee 2015).
8.1.4.
Patient-Reported cGVHD Activity Assessment (mLSS)
Changes in patient-reported symptom activity will be evaluated using the cGVHD mLSS 
(Lee 2002, Teh 2020) which has been recommended for use by the 2005 and 2014 NIH 
Consensus Conferences to capture cGVHD symptoms.
The cGVHD mLSS questionnaire asks patients to indicate the degree of “bother” that they 
experienced during the past 7 days due to symptoms in 7 domains potentially affected by chronic 
GVHD (skin, eyes and mouth, breathing, eating and digestion, muscles and joints, energy, 

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emotional distress) (Lee 2002). Published evidence supports its validity, reliability, and 
sensitivity to cGVHD severity (Lee 2015, Merkel 2016, Teh 2020).  
8.2. 
Safety Assessments  
8.2.1.
Physical Examinations
A complete physical examination will include, at a minimum, assessments of the head, 
ears, eyes, nose and throat (HEENT), dermatological, respiratory, cardiovascular, 
gastrointestinal, neurological, and lymphatic, and musculoskeletal systems. Height 
will also be measured and recorded. 
 Symptom-directed physical examination will be conducted as clinically indicated. 
 Weight will be measured when complete or symptom-directed physical examinations 
are performed. 
 Investigators should pay special attention to clinical signs related to previous serious 
illnesses. 
8.2.2. 
Neurological Examinations 
A neurological examination will include general appearance, posture and gate, motor activity, 
assessment of mental status, cranial nerves, sensory and neuromuscular function, and reflexes.
8.2.3. 
Vital Signs 
 Vital signs, systolic and diastolic blood pressure (mmHg), pulse rate (beats per 
minute), respiration rate (breaths per minute), and temperature ºF or C; collection 
method per site practice), will be measured as per standard practice. If initial blood 
pressure measurement is abnormal, repeat blood pressure measurement while the 
patient is in a semi-supine position after resting 5 minutes. 
The same units and mode should be used for a patient across all measurements.
8.2.4.
Electrocardiograms
Triplicate 12-lead ECG will be obtained using an ECG machine that automatically 
calculates the heart rate and measures PR, QRS, QT, and QTc intervals. 
 Each time at which triplicate ECGs are clinically indicated, 3 individual ECG tracings 
should be obtained as closely as possible in succession, but no more than 2 minutes 
apart. The full set of triplicates should be completed in less than 4 minutes. 
 ECGs will be recorded after the patient has rested in a supine position for at least 
10 minutes.
 If a clinically significant abnormal ECG (Grade 3 or above by CTCAE v5.0) is 
reported, the ECG needs to be reviewed by a cardiologist. 

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8.2.5.
Karnofsky/Lansky Performance Status
The Karnofsky/Lansky Performance Status allows patients to be classified as to their functional 
impairment on a scale from 0 to 100. The lower the score, the worse the survival for most serious 
illnesses. The score can be used to compare effectiveness of different therapies and to assess the 
prognosis in individual patients. The Karnofsky Scale is designed for patients aged 16 years and 
older, and the Lansky scale is designed for patients less than 16 years old (Lansky 1987). The 
Karnofsky scale is widely used validated tool in oncology settings, especially HSCT (Schag 
1984, Crooks 1991, O'Toole and Golden 1991). 
The Karnofsky and Lansky performance status are presented in Table 10.
Table 10 
Karnofsky/Lansky Performance Status  
Score 
 
Lansky (for patients < 16 years) 
Able to carry on normal activity; no special 
care is needed  
Able to carry on normal activity; no 
special care is needed 
100 
Normal, no complaints, no evidence of disease 
Fully active 
90
Able to carry on normal activity, minor signs or 
symptoms of disease. 
Minor restriction in physically strenuous 
play 
80
Normal activity with effort, some signs or 
symptoms of disease 
Restricted in strenuous play, tires more 
easily, otherwise active 
Unable to work, able to live at home, cares for 
most personal needs, a varying amount of 
assistance is needed 
Mild to moderate restriction 
70
Cares for self, unable to carry on normal activity 
or do active work 
Both greater restrictions of, and less time 
spent in active play 
60
Requires occasional assistance, but is able to 
care for most of his/her needs 
Ambulatory up to 50% of time, limited 
active play with assistance/supervision 
50
Requires considerable assistance and frequent 
medical care 
Considerable assistance required for any 
active play, fully able to engage in quiet 
play 
Unable to care for self, requires equivalent of 
institutional or hospital care, disease may be 
progressing rapidly 
Moderate to severe restriction 
40
Disabled, requires special care and assistance 
Able to initiate quite activities 
30
Severely disabled, hospitalization indicated; 
Death not imminent 
Needs considerable assistance for quiet 
activity 
20
Very sick, hospital indicated, death not 
imminent 
Limited to very passive activity initiated by 
others (eg, TV) 
10
Moribund, fatal processes progressing rapidly 
Completely disabled, not even passive play 
0 
Death 
Death 

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8.2.6.
Clinical Safety Laboratory Assessments
See Appendix 10.1 for the list of clinical laboratory tests to be performed and to the 
SoA for the timing and frequency.
The Investigator must review the laboratory report, document this review, and record 
any clinically relevant changes occurring during the study in the AE section of the 
eCRF. The laboratory reports must be filed with the source documents. Clinically 
significant abnormal laboratory findings are those which are not associated with the 
underlying disease, unless judged by the Investigator to be more severe than expected 
for the patient's condition. 
 All laboratory tests with values considered clinically significantly abnormal during 
participation in the study or within 30 days after the last dose of study intervention 
should be repeated until the values return to normal or baseline or are no longer 
considered clinically significant by the Investigator or Medical Monitor.
If such values do not return to normal/baseline within a period of time judged reasonable by the 
Investigator, the etiology should be identified, and the Sponsor notified. 
If laboratory values from non-protocol specified laboratory assessments performed at the 
institution’s local laboratory require a change in patient management or are considered clinically 
significant by the Investigator (eg, SAE or AE or dose modification), then the results must be 
recorded in the eCRF. 
8.3. 
Adverse Events and Serious Adverse Events 
The definitions of an AE or SAE can be found in Appendix 3 (Section 10.3). 
AE will be reported by the patient (or, when appropriate, by a caregiver, surrogate, or the 
patient's legally authorized representative). 
The Investigator and any qualified designees are responsible for detecting, documenting, and 
recording events that meet the definition of an AE or SAE and remain responsible for following 
up AEs that are serious, considered related to the study intervention or study procedures, or that 
caused the patient to discontinue the study intervention and/or the study (Section 7).
8.3.1.
Time Period and Frequency for Collecting AE and SAE Information
Table 11 summarizes the different observation periods for AEs, SAEs, and adverse event of 
special interest (AESI).

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Table 11 
Adverse Event Observation Periods
Type of 
Event 
Adverse Event 
Serious Adverse Event 
AESI with study drug 
Reporting 
period 
From consent 
until 90 days 
after the end of 
treatment 
From consent until 90 days after 
the last dose of study treatment 
for all SAEs, and any time after 
the end of study for SAEs 
believed to be related to study 
intervention 
From consent until 90 days after 
the last dose of study treatment, 
or 30 days after the initiation of a 
new anti-cancer therapy or any 
new therapy for GVHD, 
whichever is earlier 
Reporting 
Timelines to 
the Sponsor  
Entered into the 
clinical 
database on an 
ongoing basis   
Within 24 hours  
IRR Within 24 hours 
 
Infections: Entered into the 
clinical database on an ongoing 
basis 
 
Medical occurrences that begin before the start of study drug but after obtaining informed 
consent will be recorded on the Medical History/Current Medical Conditions section of the 
eCRF not the AE section.
The Investigator is responsible for ensuring that all AEs observed by the Investigator or reported 
by patients are properly captured in the patient’s medical records and reported in the eCRF.
Investigators are not obligated to actively seek AE or SAE after conclusion of the study 
participation. However, if the Investigator learns of any SAE, including a death, at any time after 
a patient has been discharged from the study, and he/she considers the event to be reasonably 
related to the study drug or study participation, the Investigator must promptly notify the 
Sponsor. 
If a patient has an AE recorded as COVID-19, the date of the positive COVID test should also be 
recorded, if the patient subsequently has a negative COVID test, the date of this test should also 
be recorded.
8.3.2. 
Method of Detecting AEs and SAEs
The method of recording, evaluating, and assessing causality of AE and SAE and the procedures 
for completing and transmitting SAE reports are provided in Appendix 3 (Section 10.3).
Care will be taken not to introduce bias when detecting AEs and/or SAEs. Open-ended and 
non-leading verbal questioning of the patient is the preferred method to inquire about 
AE occurrences. 
8.3.3. 
Follow-up of AEs and SAEs 
After the initial AE/SAE report, the Investigator is required to proactively follow each patient at 
subsequent visits/contacts. All SAEs, and non-serious AEs of special interest (as defined in 
Sections 10.3.2 and 10.3.3, respectively), will be followed until resolution, stabilization, the 
event is otherwise explained, or the patient is lost to follow-up (as defined in Section 7.3). 
Further information on follow-up procedures is given in Appendix 3 (Section 10.3.5). 

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8.3.4.
Regulatory Reporting Requirements for SAEs
Prompt notification by the Investigator to the Sponsor of a SAE is essential so that 
legal obligations and ethical responsibilities towards the safety of patient and the 
safety of a study intervention under clinical investigation are met.
The Sponsor has a legal responsibility to notify both the local regulatory authority and 
other regulatory agencies about the safety of a study intervention under clinical 
investigation. The Sponsor will comply with country-specific regulatory requirements 
relating to safety reporting to the regulatory authority, Institutional Review Boards 
(IRB)/Independent Ethics Committees (IEC), and investigators. 
 Investigator safety reports must be prepared for suspected unexpected serious adverse 
reactions (SUSAR) according to local regulatory requirements and Sponsor policy and 
forwarded to investigators, as necessary. 
 An Investigator who receives an Investigator safety report describing a SAE or other 
specific safety information (eg, summary or listing of SAEs) from the Sponsor will 
review and then file it along with the Investigator Brochure and will notify the 
IRB/IEC, if appropriate, according to local requirements. 
8.3.5. 
Pregnancy 
 Details of all pregnancies in female patients, and female partners of male patients, will 
be collected after the start of study intervention and until 90 days after the last dose of 
study intervention. 
 If a pregnancy is reported, the Investigator should inform the Sponsor within 24 hours 
of learning of the pregnancy and should follow the procedures outlined in Appendix 4 
(Section 10.4). 
 All female patients, and female partners of male patients becoming pregnant must be 
followed to completion/termination of the pregnancy. 
 Abnormal pregnancy outcomes (eg, spontaneous abortion, fetal death, stillbirth, 
congenital anomalies, ectopic pregnancy) are considered SAEs. 
8.3.6. 
Disease-Related Events and/or Disease-Related Outcomes Not Qualifying as AEs 
or SAEs
The following disease-related events (DREs) are common in patients with cGVHD and can be 
serious/life threatening: 
 Disease progression: if disease progression occurs, record the date first documented in 
the EOT visit eCRF. Signs and symptoms related to PD should be reported in the 
appropriate cGVHD eCRF (if changed from baseline and meet progression criteria) or 
as an SAE if the event in question meets the criteria for seriousness. 
Because these events are typically associated with the disease under study, they will not be 
reported to health authorities according to the standard process for expedited reporting of SAEs 
even though the event may meet the definition of a SAE. These events will be recorded on the 
corresponding cGVHD eCRF in the patient’s CRF within the appropriate time frame. 

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8.4.
Treatment of Overdose
Any overdose or incorrect administration of study intervention should be noted on the 
Study Drug Administration eCRF (including quantity of the excess dose and the duration of the 
overdose). AEs associated with an overdose or incorrect administration of study intervention 
should be recorded on the AE eCRF.
For this study, a study intervention overdose will be defined as a dose 
 mg/kg. No specific 
information is available on the treatment of overdose of SNDX-6352. 
The overdose will not be considered an SAE unless the outcome of the overdose meets 
seriousness criteria. All reports of overdose with and without an adverse experience must be 
reported within 24 hours to one of the individuals listed on the Sponsor contact information page 
found in the Administrative Binder. The patient should be carefully monitored for potential 
adverse reactions and symptomatic treatment instituted as per institutional standards of care.
Decisions regarding dose interruptions or modifications will be made by the Investigator in 
consultation with the Medical Monitor based on the clinical evaluation of the patient. 
8.5. 
Pharmacokinetics 
Axatilimab levels in plasma samples will be determined using a validated enzyme-linked 
immunosorbent assay (ELISA). 

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Refer to the Study Laboratory Manual for instructions on sample collection and shipment to the 
central laboratories. 
Other samples may be used for research to develop methods, assays, prognostics and/or 
companion diagnostics related to immune modulation, disease processes and pathways 
associated with disease state, and/or mechanism of action of axatilimab. 
Samples may be stored for a maximum of 10 years (or according to local regulations) following 
the last patient’s last visit for the study at a facility selected by the Sponsor to enable further 
analysis of biomarker responses to axatilimab. 

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9.
STATISTICAL CONSIDERATIONS
9.1.
Statistical Hypothesis
There are three randomized arms in the study with three different dose levels. The primary 
objective in each arm is to determine the efficacy of axatilimab with respect to ORR in the first 6 
cycles. In each arm, the study will test the null hypothesis that the ORR in the first 6 cycles is 
 
9.2.
Sample Size Determination
The sample size was calculated to provide adequate power for testing the statistical hypotheses 
regarding the primary endpoint of ORR in the first 6 cycles. Based on Simon’s optimal 2-stage 
design, a total of 70 patients in each arm will provide approximately 90% power to detect a true 
ORR in the first 6 cycles of 50% with a 1-sided significance level of 0.025 in the arm.  
The study will enroll patients in each arm in two stages, with 27 patients enrolled in the first 
stage. An IA in each arm will be conducted when the first 27 patients have had the opportunity to 
complete 3 cycles of therapy, and the dose will be evaluated for futility or unacceptable toxicity. 
In addition, a futility assessment may also be conducted at the time when each patient has had 
the opportunity to complete 6 cycles of therapy. Details of the IA are described in Section 9.4.5.   
A final efficacy analysis will be performed when all patients have had the opportunity to 
patients have had a response to axatilimab (PR or CR), as defined by NIH 2014 cGVHD criteria. 
The final boundary for efficacy will be re-calculated if there is over enrollment in the second 
stage of the design. For example, if the total number of randomized patients in a dose level is 80, 
will be recalculated if there is over enrollment), this will indicate a 90% posterior probability of 
the toxicity rate exceeding 20%, and the final determination of acceptability of a given dose will 
be based on the overall benefit/risk indicated by review of the totality of evidence.  
 
9.3. 
Population for Analyses 
For purposes of analysis, the following populations are defined:
Population 
Description 
Intent-to-treat 
Analysis Set (ITT) 
ITT Analysis Set for each dose level consists of all patients randomized to the 
dose level.  
Response Evaluable 
Analysis Set  
Response Evaluable Analysis Set for each dose level consists of all patients 
who were randomized to the dose level, received at least one dose of study 
drug and had at least one post-baseline assessment.  
Safety Analysis Set 
Safety Analysis Set consists of all enrolled patients who received at least one 
dose of study drug during the study. 

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PK Analysis Set 
PK Analysis Set consists of all patients who receive at least one dose of 
axatilimab and have at least one valid plasma concentration of axatilimab 
determined. 
Pharmacodynamic 
Analysis Set 
Pharmacodynamic Analysis Set consists of patients who are exposed to 
axatilimab and have sufficient post-baseline samples collected to permit 
pharmacodynamic analyses. 
9.4. 
Statistical Methods 
Detailed methodology for summary and statistical analyses of the data collected in this study will 
be documented in a statistical analysis plan (SAP), which will be maintained by the Sponsor. The 
SAP may modify the plans outlined in the protocol; however, any major modifications will also 
be reflected in a protocol amendment. The SAP will be finalized before database lock and will 
describe the analysis populations to be included in the analyses, and procedures for accounting 
for missing, unused, and spurious data. This section is a summary of the planned statistical 
analyses. 
In general, summary tabulations will be presented that display the number of observations, mean, 
standard deviation, median, 25th percentile (first quartile), 75th percentile (third quartile), 
minimum, and maximum for continuous variables, and the number and percent (of non-missing 
values) per category for categorical data. Time-to-event data will be analyzed using the Kaplan-
Meier method and results will be summarized by 25th, 50th (median) and 75th percentiles with 
associated 2-sided 95% CIs, as well as the percentage of censored observations.  
The statistical analyses will be performed using SAS® version 9.4 or later (SAS Institute Inc, 
Cary NC). Programming specifications will be prepared that describe the datasets and variables 
created for this study. The datasets will be prepared using the most recent version of CDISC’s 
Study Data Tabulation Model (SDTM) and Analysis Dataset Model (ADaM). The source 
datasets from which a statistical analysis is performed (including interim reviews) will be 
archived with the Sponsor.
9.4.1.
Efficacy Analysis
Efficacy analyses will be performed on the ITT analysis set.
Endpoint 
Statistical Analysis Methods 
Primary 
The primary efficacy endpoint is overall response rate (ORR) in the first 6 cycles, 
defined as the proportion of patients with objective response (OR) during the first 6 
cycles, where the first 6 cycles is defined as the time from randomization up to Day 
169 or the beginning of Cycle 7, whichever is later; and OR is defined as CR or PR 
as defined by the NIH Consensus Development Project on Clinical trials in cGVHD. 
Exact 95% confidence intervals using binomial distribution will be provided. 
Key Secondary 
Proportion of patients with a clinically significant improvement in normalized score 
using the cGVHD mLSS will be calculated along with exact 95% CIs.  

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Endpoint 
Statistical Analysis Methods 
Secondary 
 
ORR on study is defined as proportion of patients with OR anytime on study 
as defined by the 2014 NIH Consensus Development Project on Criteria for 
Clinical Trials in cGVHD. Exact 95% confidence intervals using binomial 
distribution will be provided. 
 
The DOR is defined as the time of initial response of PR or CR until 
documented progression of cGVHD, or start of new therapy, or death for 
any reason. DOR will be summarized descriptively using the Kaplan-Meier 
method.  
 
SRR defined as proportion of patients with sustained response. The 
sustained response is defined as OR lasting for at least 20 weeks (140 days) 
from the time of initial response. Responses by organ system will be 
assessed based on the 2014 NIH Consensus Development Project on Clinical 
Trials in cGVHD.  
 
Organ-specific response rate defined as the proportion of patients with OR 
for the nine individual organs based on 2014 NIH Consensus Development 
Project on Criteria for Clinical Trials in cGVHD (Skin, Eyes, Mouth, 
Esophagus, Upper GI, Lower GI, Liver, Lungs and Joints and Fascia) will be 
summarized with exact 95% CIs.  
 
Joints and fascia response rate defined as the proportion of patients with 
Joints and Fascia response based on refined NIH response algorithm for 
cGVHD will be calculated along with 95% CIs.  
 
Percent reductions in average daily doses (or equivalent) of corticosteroid 
after study entry will be summarized descriptively along with 95% CIs. 
 
Proportion of patients who discontinue corticosteroid use after study entry 
will be summarized along with exact 95% CIs.  
 
Percent reductions in average daily doses (or equivalent) of calcineurin 
inhibitors after study entry will be summarized descriptively along with 95% 
CIs. 
 
Proportion of patients who discontinue calcineurin inhibitors after study 
entry will be summarized along with exact 95% CIs.  

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Endpoint 
Statistical Analysis Methods 
Exploratory  
 
FFS is defined as the time from randomization to addition of another 
systemic immune suppressive therapy for cGVHD, relapse of underlying 
malignancy, or death whichever is earlier. The proportion of patients with 
FFS at Cycle 7 Day 1 (Day 168) and Cycle 14 Day 1 (1 year) will be 
calculated along with 95% CIs.  
 
Overall survival is defined as time from randomization to the date of death 
(due to any cause). Patients who are alive or lost to follow-up (as of the data 
analysis cutoff date) will be censored. The duration of OS will be 
summarized descriptively using the Kaplan-Meier method along with 95% 
CIs. 
 
Time to response will be calculated for patients who achieve a CR or PR. 
For such patients, TTR is defined as time from randomization to the first 
date the patient achieved a PR or CR. The duration of TTR will be 
summarized descriptively.  
9.4.2. 
Safety and Tolerability Analysis
All safety analyses will be performed on the Safety Analysis Set. Safety will be assessed by 
clinical review of all relevant parameters including vital sign measurements, Karnofsky/Lansky 
performance status, AEs, SAEs, physical and neurological examinations, ECG results, and 
laboratory values. Summary tables and listings will be provided for all reported TEAEs, defined 
as AEs that start on or after the first administration of study treatment. The reported AE term will 
be assigned a standardized preferred term using the current version of the Medical Dictionary for 
Regulatory Activities (MedDRA). Treatment-emergent adverse event will be summarized based 
on the numbers and percentages of patients experiencing the event by MedDRA system organ 

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class and preferred term. If a patient experiences repeat episodes of the same AE, then the event 
with the highest severity grade and strongest causal relationship to study treatment will be used 
for purposes of incidence tabulations. 
Tabular summaries will be provided for the following:
 All TEAEs 
 TEAEs by relationship to study drug treatment and maximum severity grade
 TEAEs with action of study intervention treatment delayed, dose skipped, or dose 
reduced 
 TEAEs with action of study treatment discontinued 
 SAEs 
 Changes in Karnofsky/Lansky performance status score
 Changes in chemistry and hematology parameters 
 Changes in vital signs, weight and ECGs
9.4.3. 
Pharmacokinetic Analyses
Plasma samples for population PK assessment will be analyzed for concentrations of axatilimab. 
A population PK modeling approach will be used to describe the PK of axatilimab in the target 
patient population. PK parameters such as clearance and volume of distribution will be defined 
for patients receiving axatilimab. In the analysis, a number of covariates, including patient 
demographic variables (eg, age, gender, body weight, and race) clinical laboratory parameters 
(eg, AST, ALT, CrCL) and concomitant medications will be evaluated to determine if they 
contribute to differences in PK estimates among individuals.
A separate PK analysis plan will be prepared prior to data analysis. Data from other studies of 
axatilimab may be pooled for this analysis, if necessary, for robust model identification.  

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9.4.5.
Interim Analysis
Interim analyses will occur when the first 27 patients in each cohort have had the opportunity to 
complete 3 (IA #1) and 6 (IA #2) cycles of therapy. The addition of the first IA to the Simon’s 2-
stage design does not inflate Type I error. With the assumption that 70% of responses occur in 
the first 3 cycles, adding this futility assessment slightly reduces the overall study power from 
90% to 83% but provides a 67% probability of early stopping under the null to reduce potential 
over-randomization to a futile dose.   
Toxicity evaluation will coincide with the futility assessments. Toxic event is defined as any 
considered treatment-related and result in medical intervention or hospitalization will be counted 
as a toxic event. 
For IA #1, the stopping rules for unacceptable toxicity are established using Bayesian method 
probability of 90%. The operating characteristics of this design are calculated using Bayesian 
Toxicity Monitoring Software (BTM) by The University of Texas MD Anderson Cancer Center. 
Further details will be provided in the SAP.  
Simon’s optimal 2-stage design will be implemented within each dose cohort. In the first stage 
27 patients will be randomized to each of the 3 dose cohorts. To limit the potential exposure of 
patients to an inefficacious dose and obviate the need for a pause in accrual, the initial futility 
analysis will be based on an early endpoint (ie, overall response in the first 3 cycles). Each dose 
will be evaluated for futility and unacceptable toxicity as follows: 
 IA #1: Futility assessment based on responses in the first 3 cycleswill be conducted. 
This assessment will occur when the first 27 patients in each cohort have had the 
first 3 cycles of axatilimab (up to and including cycle 4, day 1 assessment), the 
randomization to this dose level may be stopped for futility. Safety assessment will 
3) 
TEAE that is attributed to study drug. Grade 2 events that are considered treatment-
related and result in medical intervention or hospitalization will be counted as a toxic 
event. 
 IA #2: IA #2 will consist of an overall evaluation of available clinical data. It will be 
conducted when the first 27 patients in each cohort have had the opportunity to 
randomization to this dose level will be stopped for futility. For IA#2, given the full 
enrollment of the study as of this amendment, the rate of toxicity events will be 
provided for all treated patients and will be reviewed as part of the overall benefit/risk 
assessment. For the overall benefit/risk assessment, a comprehensive safety and 
efficacy analysis will be provided to the IDMC: 
 Safety for all participants. 
 Efficacy for all participants who have had the opportunity to receive 3 cycles of 
axatilimab. 

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Study randomization will not pause while data from the interim analyses are being evaluated. 
An Independent Data Monitoring Committee will evaluate all data that are available at the time 
of the data cut for the interim analyses, and provide a recommendation on continued use of the 
available axatilimab dose levels.  
A final efficacy analysis will be performed when all patients have had the opportunity to 
patients have had a response to axatilimab (PR or CR), as defined by NIH 2014 cGVHD criteria. 
The final boundary for efficacy will be re-calculated if there is over enrollment in the second 
stage of the design. For example, if the total number of randomized patients in a dose level is 80, 
 
At the final analysis, if 19 or more patients out of the total 70 patients experience a toxic event 
(the boundary will be recalculated if there is over enrollment), this will indicate a 90% posterior 
probability of the toxicity rate exceeding 20% and the final determination of acceptability of a 
given dose will be based on the overall benefit/risk indicated by review of the totality of 
evidence.  
Table 12 
Interim Analysis #1 Toxicity Stopping Boundaries (Rate = 0.20 with Prior 
[1,1] and Posterior Prob. of 0.90)
Total Number of Patients 
Number of Patients with Toxicities 
Considered Unacceptable 
27 
 

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10.
APPENDICES
10.1.
Appendix 1: Regulatory, Ethical, and Study Oversight 
Considerations 
10.1.1.
Regulatory and Ethical Considerations
This study will be conducted in accordance with the protocol and with the following:
Consensus ethical principles derived from international guidelines including the 
Declaration of Helsinki and Council for International Organizations of Medical 
Sciences (CIOMS) International Ethical Guidelines
Applicable ICH Good Clinical Practice (GCP) Guidelines
Applicable laws and regulations
The protocol, protocol amendments, ICF, Investigator Brochure, and other relevant 
documents (eg, advertisements) must be submitted to an IRB/IEC by the Investigator 
and reviewed and approved by the IRB/IEC before the study is initiated.
 Any amendments to the protocol will require IRB/IEC approval before 
implementation of changes made to the study design, except for changes necessary to 
eliminate an immediate hazard to study patients.
The Investigator will be responsible for the following:
 Providing written summaries of the status of the study to the IRB/IEC annually or 
more frequently in accordance with the requirements, policies, and procedures 
established by the IRB/IEC
 Notifying the IRB/IEC of SAEs or other significant safety findings as required by 
IRB/IEC procedures
 Providing oversight of the conduct of the study at the site and adherence to 
requirements of 21 CFR, ICH guidelines, the IRB/IEC, European regulation 
536/2014 for clinical studies (if applicable), and all other applicable local 
regulations
10.1.2. 
Informed Consent Process
 The Investigator or his/her representative will explain the nature of the study to the 
patient or his/her legally authorized representative and answer all questions regarding 
the study. 
 Patients must be informed that their participation is voluntary. Patients or their legally 
authorized representative will be required to sign a statement of informed consent that 
meets the requirements of 21 CFR 50, local regulations, ICH guidelines, Health 
Insurance Portability and Accountability Act (HIPAA) requirements, where 
applicable, and the IRB/IEC or study center. 

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 A parent/guardian should provide consent for pediatric patients unable to provide 
consent themselves; in addition, where applicable pediatric patients should sign their 
own assent form.
 The medical record must include a statement that written informed consent was 
obtained before the patient was enrolled in the study and the date the written consent 
was obtained. The authorized person obtaining the informed consent must also sign the 
ICF. 
 Patients must be re-consented to the most current version of the ICF(s) during their 
participation in the study.
 A copy of the ICF(s) must be provided to the patient or the patient’s legally authorized 
representative. 
A patient who is rescreened is not required to sign another ICF if the rescreening occurs within 
(28) days from the previous ICF signature date. 
The ICF will contain a separate section that addresses the use of blood samples for optional 
future research. The Investigator or authorized designee will explain to each patient the 
objectives of the future research. Patients will be told that they are free to refuse to participate 
and may withdraw their consent at any time and for any reason during the storage period. A 
separate signature will be required to document a patient's agreement to allow any remaining 
specimens to be used for future research. Patients who decline to participate in this optional 
research will not provide this separate signature. 
10.1.3. 
Data Protection 
 Patients will be assigned a unique identifier by the Sponsor. Any patient records or 
datasets that are transferred to the Sponsor will contain the identifier only; patient 
names or any information which would make the patient identifiable will not be 
transferred. 
 The patient must be informed that his/her personal study-related data will be used by 
the Sponsor in accordance with local data protection law. The level of disclosure must 
also be explained to the patient. 
 The patient must be informed that his/her medical records may be examined by 
Clinical Quality Assurance auditors or other authorized personnel appointed by the 
Sponsor, by appropriate IRB/IEC members, and by inspectors from regulatory 
authorities. 
10.1.4. 
Independent Data Monitoring Committee
An IDMC has been established for this study and specific guidelines on the operation and 
purpose of the IDMC is documented in a Charter. The committee includes at least three 
members, including a statistician and medical oncologists experienced in the treatment of 
cGVHD. Safety review meetings will be held as per the IDMC charter and as needed if any 
unexpected safety signals emerge during the course of the study. The IDMC will be responsible 
for independently evaluating safety data of patients enrolled to the study. Decisions on study 

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termination, amendment of the protocol, or cessation of patient recruitment will be made after 
recommendations from the IDMC have been assessed by the Sponsor. 
10.1.5. 
Dissemination of Clinical Study Data 
A clinical study report will be developed by the Sponsor at completion of data analysis. This 
report will be a clinical and statistical integrated report, according to the ICH E3 guidelines. 
Sponsor will register the study and post study results regardless of outcome on a publicly 
accessible website in accordance with the applicable laws and regulations. 
10.1.6. 
Data Quality Assurance
 All patient data relating to the study will be recorded on printed or electronic CRF 
unless transmitted to the Sponsor or designee electronically (eg, laboratory data). The 
Investigator is responsible for verifying that data entries are accurate and correct by 
physically or electronically signing the CRF. 
 The Investigator must maintain accurate documentation (source data) that supports the 
information entered in the CRF.
 The Investigator must permit study-related monitoring, audits, IRB/IEC review, and 
regulatory agency inspections and provide direct access to source data documents. 
 Monitoring details describing strategy (eg, risk-based initiatives in operations and 
quality such as Risk Management and Mitigation Strategies and Analytical Risk-Based 
Monitoring), methods, responsibilities and requirements, including handling of 
noncompliance issues and monitoring techniques (central, remote, or on-site 
monitoring) are provided in the Monitoring Plan. 
 The Sponsor or designee is responsible for the data management of this study 
including quality checking of the data. 
 The Sponsor assumes accountability for actions delegated to other individuals (eg, 
Contract Research Organizations). 
 Study monitors will perform ongoing source data verification to confirm that data 
entered into the CRF by authorized site personnel are accurate, complete, and 
verifiable from source documents; that the safety and rights of patients are being 
protected; and that the study is being conducted in accordance with the currently 
approved protocol and any other study agreements, ICH GCP, and all applicable 
regulatory requirements. 
 Records and documents, including signed ICFs, pertaining to the conduct of this study 
must be retained by the Investigator per ICH-GCP and local regulations or institutional 
policies. No records may be destroyed during the retention period without the written 
approval of the Sponsor. No records may be transferred to another location or party 
without written notification to the Sponsor. 

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10.1.7.
Source Documents
Source documents provide evidence for the existence of the patient and substantiate 
the integrity of the data collected. Source documents are filed at the Investigator’s site.
Data entered in the eCRF that are transcribed from source documents must be 
consistent with the source documents or the discrepancies must be explained. The 
Investigator may need to request previous medical records or transfer records, 
depending on the study. Also, current medical records must be available. 
 Source documents are original documents, data, and records from which the patient’s 
eCRF data are obtained. These include but are not limited to hospital records, clinical 
and office charts, laboratory and pharmacy records, diaries, microfiches, radiographs, 
and correspondence. 
10.1.8. 
Study and Site Closure 
The Sponsor designee reserves the right to close the study site or terminate the study at any time 
for any reason at the sole discretion of the Sponsor. Study sites will be closed upon study 
completion. A study site is considered closed when all required documents and study supplies 
have been collected and a study-site closure visit has been performed. 
The Investigator may initiate study-site closure at any time, provided there is reasonable cause 
and sufficient notice is given in advance of the intended termination. 
Reasons for the early closure of a study site by the Sponsor or Investigator may include but are 
not limited to: 
 Failure of the Investigator to comply with the protocol, the requirements of the 
IRB/IEC or local health authorities, the Sponsor's procedures, or GCP guidelines 
 Inadequate recruitment of patients by the Investigator 
 Discontinuation of further study intervention development 
10.1.9.
Publication Policy
The results of this study may be published or presented at scientific meetings. If this is 
foreseen, the Investigator agrees to submit all manuscripts or abstracts to the Sponsor 
before submission. This allows the Sponsor to protect proprietary information and to 
provide comments.
The Sponsor will comply with the requirements for publication of study results. In 
accordance with standard editorial and ethical practice, the Sponsor will generally 
support publication of multicenter studies only in their entirety and not as individual 
site data. In this case, a coordinating Investigator will be designated by mutual 
agreement. 
 Authorship will be determined by mutual agreement and in line with International 
Committee of Medical Journal Editors authorship requirements. 

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10.2.
Appendix 2: Clinical Laboratory Tests
The tests detailed in Table 13 will be performed by the local laboratory.
In addition to the scheduled assessments (specified in SoA), clinical laboratory 
evaluations may be repeated during the treatment period per the Investigator’s clinical 
judgment.
Protocol-specific requirements for inclusion or exclusion of patients are detailed in 
Section 5 of the protocol. 
Laboratory assessments will be done as specified in SoA (Section 1.3). Additional 
laboratory assessments may be performed at any time during the study as determined 
necessary by the Investigator or required by local regulations. 
Table 13 
Protocol-Required Safety Laboratory Assessments 
Hematology 
White blood cell count (WBC) with 
differential (Neutrophils, Lymphocytes, 
Monocytes, Eosinophils, Basophils) 
Hematocrit
 
Hemoglobin 
 
Red blood cell (RBC) 
 
Platelet count 
 
Clinical Chemistriesa 
 
Alanine Aminotransferase (ALT) 
 
Aspartate Aminotransferase (AST) 
 
Alkaline phosphatase 
 
Gamma-glutamyl transferase (GGT) 
 
Total bilirubin (fractionated) 
 
Albumin 
 
Calcium 
 
Blood urea nitrogen (BUN)b 
 
Sodium 
 
Creatinine 
 
Chloride 
 
Potassium 
 
Glucose 
 
Bicarbonate 
 
Phosphorus/phosphates 
 
Lactic dehydrogenase 
 
Uric acid 
 
Total protein 
 
Amylase 
 
Magnesium (Screening only, unless clinically 
indicated) 
 
Lipase 
 
CPK 

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Urinalysis 
 
Basic Urinalysis (dipstick, including 
macroscopic appearance, bilirubin, blood, 
color, glucose, ketones, leukocyte esterase, 
nitrite, pH, protein, specific gravity, 
urobilinogen; prior to each administration of 
study intervention treatment after C1 if 
clinically indicated) 
Full urinalysis (dipstick plus microscopic 
evaluation) to be performed only at the 
Screening and EOT visits). 
Other Laboratory Assessments
Coagulation factors, including PT or 
International Normalized Ratio (INR) and 
aPTT (Screening only) 
Human chorionic gonadotropin (hCG) 
pregnancy test (as needed for women of 
childbearing potentialc 
 
HCV RNAd
 
a Details of liver chemistry stopping criteria and required actions and follow-up assessments after liver stopping or 
monitoring event are given in Section 6.7 (stopping rules and dose modification). 
b If urea level is reported by the local site laboratory instead of blood urea nitrogen (BUN), BUN level should be 
calculated formulas detailed in Section 10.2 and entered in the appropriate field in the eCRF. 
c For female patients of child-bearing potential, a serum pregnancy test is required to be performed during screening 
and within 3 days before the first study intervention dose if the screening pregnancy test is performed more than 3 
days before the first study intervention dose. A serum pregnancy is also required at the end of study. During the 
study, either urine or serum pregnancy tests are performed. Pregnancy testing is to be repeated every 4 weeks. 
d Polymerase chain reaction is required and must be negative for HCV RNA in patients positive for HCV antibody. 

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10.3.
Appendix 3: Adverse Events: Definitions and Procedures for 
Recording, Evaluating, Follow-up, and Reporting 
10.3.1.
Definition of AE
AE Definition
 
An AE is any untoward medical occurrence in a patient or clinical investigation patient 
administered a pharmaceutical product and that does not necessarily have a causal relationship 
with this treatment (ICH E6:1.2). 
 
NOTE: An AE can therefore be any unfavorable and unintended sign (including an abnormal 
laboratory finding), symptom, or disease (new or exacerbated) temporally associated with the use 
of study intervention. 
Events Meeting the AE Definition 
Any abnormal laboratory test results (hematology, clinical chemistry, or urinalysis) or other safety 
assessments (eg, ECG, radiological scans, vital signs measurements), including those that worsen 
from baseline, considered clinically significant in the medical and scientific judgment of the 
Investigator (ie, not related to progression of underlying disease). 
 
Worsening of a pre-existing medical condition, (ie, diabetes, migraine headaches, gout) should be 
considered an AE if there is either an increase in severity, frequency, or duration of the condition or 
an association with significantly worse outcomes. 
 
New conditions detected or diagnosed after study intervention administration even though it may 
have been present before the start of the study. 
 
Signs, symptoms, or the clinical sequelae of a suspected drug-drug interaction. 
 
Signs, symptoms, or the clinical sequelae of a suspected overdose of either study intervention or a 
concomitant medication. Overdose per se will not be reported as an AE/SAE unless it is an 
intentional overdose taken with possible suicidal/self-harming intent. Such overdoses should be 
reported regardless of sequelae. 
Events NOT Meeting the AE Definition  
 
Any clinically significant abnormal laboratory findings or other abnormal safety assessments which 
are associated with the underlying disease, unless judged by the Investigator to be more severe than 
expected for the patient’s condition. 
 
The disease/disorder being studied or expected progression, signs, or symptoms of the 
disease/disorder being studied, unless more severe than expected for the patient’s condition. 
 
Medical or surgical procedure (eg, endoscopy, appendectomy): the condition that leads to the 
procedure is the AE. 
 
Situations in which an untoward medical occurrence did not occur (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. 

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10.3.2.
Definition of SAE
If an event is not an AE per definition above, then it cannot be an SAE even if serious conditions 
are met (eg, hospitalization for signs/symptoms of the disease under study, death due to 
progression of disease). 
A SAE is defined as any untoward medical occurrence that, at any dose: 
1. Results in death 
2. Is life-threatening (ie, places the patient at immediate risk of death) 
The term 'life-threatening' in the definition of 'serious' refers to an event in which the patient was at risk 
of death at the time of the event. It does not refer to an event, which hypothetically might have caused 
death, if it were more severe. 
3. Requires inpatient hospitalization or prolongation of existing hospitalization 
In general, hospitalization signifies that the patient has been detained (usually involving at least an 
overnight stay) at the hospital or emergency ward for observation and/or treatment that would not have 
been appropriate in the physician’s office or outpatient setting. Complications that occur during 
hospitalization are AEs. If a complication prolongs hospitalization or fulfills any other serious criteria, 
the event is serious. When in doubt as to whether “hospitalization” occurred or was necessary, the AE 
should be considered serious. 
Hospitalization for elective treatment of a pre-existing condition that did not worsen from baseline is 
not considered an AE. 
4. Results in persistent or significant disability/incapacity 
 
The term disability means a substantial disruption of a person’s ability to conduct normal life 
functions. 
 
This definition is not intended to include experiences of relatively minor medical significance such 
as uncomplicated headache, nausea, vomiting, diarrhea, influenza, and accidental trauma (eg, 
sprained ankle) which may interfere with or prevent everyday life functions but do not constitute a 
substantial disruption. 
5. Is a congenital anomaly/birth defect 
6.
Is an important medical event that although may not result in death, be life-threatening, or require 
hospitalization, may be considered a serious adverse drug experience when, based upon appropriate 
medical judgment, may jeopardize the patient and may require medical or surgical intervention to 
prevent one of the outcomes listed in this definition. 
 
Examples of such events include invasive or malignant cancers, intensive treatment in an 
emergency room or at home for allergic bronchospasm, blood dyscrasias or convulsions that do 
not result in hospitalization, or development of drug dependency or drug abuse. 
10.3.3. 
Definition of Adverse Events of Special Interest (AESI) 
Adverse Events of Special Interest for SNDX-6352 are by the Sponsor defined as: 
 
Infusion-related reactions including hypersensitivity reactions 
 
Infections   

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10.3.4.
Definition of Suspected and Unexpected Adverse Reaction
Suspected adverse reactions are defined as: 
any AE for which there is a reasonable possibility that the study intervention caused the AE. For 
the purposes of Sponsor regulatory safety reporting, “reasonable possibility” means there is 
evidence to suggest a causal relationship between the study intervention and the AE.  
Unexpected Adverse events are defined as:
AE which is not listed in the reference safety information of the IB of the study intervention or is 
not listed at the specificity or severity that has been observed.  
10.3.5. 
Recording, Assessment, and Follow-Up of AE and/or SAE 
AE and SAE Recording 
 
When an AE/SAE occurs, it is the responsibility of the Investigator to review all documentation 
(eg, hospital progress notes, laboratory reports, and diagnostics reports) related to the event. 
 
The Investigator will then record all relevant AE/SAE information in the eCRF/SAE form.  
 
It is not acceptable for the Investigator to send photocopies of the patient’s medical records to the 
Medical Monitor/Syndax in lieu of completion of the AE/SAE CRF/SAE form. 
 
There may be instances when copies of medical records for certain cases are requested by the 
Medical Monitor/Syndax. In this case, all patient identifiers, with the exception of the patient 
number, will be redacted on the copies of the medical records before submission. The Investigator 
will attempt to establish a diagnosis of the event based on signs, symptoms, and/or other clinical 
information. Whenever possible, the diagnosis (not the individual signs/symptoms) will be 
documented as the AE/SAE. 
Assessment of Intensity 
AE severity will be evaluated by the Investigator in accordance with the NCI CTCAE v5.0. For AEs 
that are not adequately addressed in the NCI CTCAE, the Investigator should classify the intensity of 
the AE using the following guidelines: 
 
Grade 1:  Mild:  Aware of sign or symptom, but easily tolerated; no intervention needed 
 
Grade 2:  Moderate:  Discomfort enough to cause interference with usual activity, minimal 
non-invasive intervention indicated (eg, short course of antibiotics) 
 
Grade 3:  Severe:  Medically significant but not immediately life-threatening; incapacitation 
with inability to work or do usual activity 
 
Grade 4:  Life-threatening:  Refers to an event in which the patient was at risk of death at the 
time of the event, as judged by the Investigator; urgent/emergent intervention indicated. This 
category should not be used for an event that hypothetically might have caused death if it were 
more severe. 
 
Grade 5:  Fatal outcome. 
It will be left to the Investigator’s clinical judgment to determine whether an AE is of sufficient 
severity to require the patient’s removal from treatment or from the study. A patient may also 
voluntarily withdraw consent from treatment due to what she/he perceives as an intolerable AE. If 
either of these situations arises, the patient should be strongly encouraged to undergo an end-of-study 
assessment and be under medical supervision until symptoms cease or the condition becomes stable. 

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An event is defined as ‘serious’ when it meets at least 1 of the predefined outcomes as described in the 
definition of an SAE, NOT when it is rated as severe.
Assessment of Causality 
The Investigator must make a judgment regarding whether or not the AE was related to the study drug. 
The Investigator will also review laboratory test results and determine whether an abnormal value in an 
individual patient represents a clinically significant change from baseline and whether or not the 
change is related to study intervention. Guidelines for assessing relationship to study intervention are as 
follows: 
The study intervention relationship will be assessed by means of the question: “Is there a reasonable 
possibility that the event may have been caused by study intervention?” The causal relationship 
between an AE and the study intervention will be determined by the following definitions: 
Definitely Related – There is clear evidence to suggest a causal relationship, and other possible 
contributing factors can be ruled out. The clinical event, including an abnormal laboratory test result, 
occurs in a plausible time relationship to study intervention administration and cannot be explained by 
concurrent disease or other drugs or chemicals. The response to withdrawal of the study intervention 
(dechallenge) should be clinically plausible. The event must be pharmacologically or 
phenomenologically definitive, with use of a satisfactory rechallenge procedure if necessary. 
Probably Related – There is evidence to suggest a causal relationship, and the influence of other 
factors is unlikely. The clinical event, including an abnormal laboratory test result, occurs within a 
reasonable time after administration of the study intervention, is unlikely to be attributed to concurrent 
disease or other drugs or chemicals, and follows a clinically reasonable response on withdrawal 
(dechallenge). Rechallenge information is not required to fulfill this definition. 
Possibly Related – There is some evidence to suggest a causal relationship (eg, the event occurred 
within a reasonable time after administration of the trial medication). However, other factors may have 
contributed to the event (eg, the participant’s clinical condition, other concomitant events). Although 
an AE may rate only as “possibly related” soon after discovery, it can be flagged as requiring more 
information and later be upgraded to “probably related” or “definitely related”, as appropriate. 
Unlikely to be related – A clinical event, including an abnormal laboratory test result, whose temporal 
relationship to study intervention administration makes a causal relationship improbable (eg, the event 
did not occur within a reasonable time after administration of the study intervention) and in which 
other drugs or chemicals or underlying disease provides plausible explanations (eg, the participant’s 
clinical condition, other concomitant treatments). 
Not Related - The AE is completely independent of study intervention administration, and/or evidence 
exists that the event is definitely related to another etiology. There must be an alternative, definitive 
etiology documented by the clinician. 
When assessing the relationship between administration of the study drugs and the AE, the following 
should be considered: 
 
Follows a temporal sequence from administration of investigational product 
 
Is a known response to the investigational product based on clinical or preclinical data 
 
Could not be explained by the known characteristics of the patient’s clinical state, 
environmental or toxic factors, or other therapy administered to the patient 
 
Disappears or decreases upon cessation or reduction of dose of investigational product 
 
Reappears or worsens when investigational product is reinstated 
The Investigator must continue to follow all AEs until resolution or the Investigator assesses them as 
chronic or stable. This follow-up may extend after the end of the study. The Investigator must promptly 
report to his or her IRB/EC all unanticipated problems involving risks to patients, per institutional 

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requirements. This includes death from any cause and all SAEs reasonably or possibly associated with 
the use of study drug according to IRB/EC procedures.
Follow-up of AEs and SAEs 
The Investigator is obligated to perform or arrange for the conduct of supplemental 
measurements and/or evaluations as medically indicated or as requested by Medical 
Monitor/Syndax to elucidate the nature and/or causality of the AE or SAE as fully as possible. 
This may include additional laboratory tests or investigations, histopathological examinations, or 
consultation with other health care professionals. 
 
[If a patient dies during participation in the study or during a recognized follow-up period, the 
Investigator will provide Medical Monitor/Syndax with a copy of any post-mortem findings 
including histopathology. 
 
New or updated information will be recorded in the originally completed CRF. 
 
The Investigator will submit any updated SAE data to the Sponsor within 24 hours of receipt of 
the information. 
10.3.6. 
Reporting of SAEs and AESI
SAE/AESI Reporting to Syndax via email or facsimile 
 
On discovery, all SAEs and infusion-related reactions, including hypersensitivity reactions AESIs 
should be immediately reported (latest within 24 hours of knowledge of the event) to Syndax by 
completing the SAE report. Infusion-related reactions, including hypersensitivity reactions 
AESIs, regardless of seriousness, are reported via an SAE report form. If the AESI does not meet 
the criteria for seriousness, the form should be completed, but no criteria for seriousness should 
be checked on the SAE form. The completed SAE form and supporting documents should be 
emailed to:  
SyndaxSAEReporting@syndax.com 
Please note that this email address is for the reporting of SAE, AESI, and pregnancy information 
only. 
Back-up reporting method: 
 
Back-up reporting method to Syndax is fax of SAE form to 1-888-529-3580. 
 
Contacts for SAE reporting can be found in Investigational Site File 

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10.4.
Appendix 4: Contraceptive Guidance and Collection of Pregnancy 
Information 
Definitions:
Woman of Childbearing Potential (WOCBP)
A woman is considered fertile following menarche and until becoming post-menopausal unless 
permanently sterile (ie, bilateral salpingectomy, bilateral oophorectomy, or complete 
hysterectomy).
If fertility is unclear (e.g., amenorrhea in adolescents or athletes) and a menstrual cycle cannot be 
confirmed before first dose of study intervention, additional evaluation should be considered. 
Women in the following categories are not considered WOCBP 
Women will be considered postmenopausal if they have been amenorrheic for 12 months without 
an alternative medical cause. The following age-specific requirements apply: 
 Women <50 years of age would be considered post-menopausal if they have been 
amenorrheic for 12 months or more following cessation of exogenous hormonal 
treatments and if they have luteinizing hormone and follicle-stimulating hormone 
levels in the post-menopausal range for the institution. 
 
d post-menopausal if they have been 
amenorrheic for 12 months or more following cessation of all exogenous hormonal 
treatments, had radiation-induced menopause with last menses >1 year ago, had 
chemotherapy-induced menopause with last menses >1 year ago. 
Note: Females on hormone replacement therapy (HRT) and whose menopausal status is 
in doubt will be required to use one of the non-estrogen hormonal highly effective 
contraception methods if they wish to continue their HRT during the study. Otherwise, 
they must discontinue HRT to allow confirmation of postmenopausal status before study 
randomization. 
Other conditions: 
1. Premenarchal 
2. Premenopausal female with 1 of the following: 
Documented hysterectomy 
Documented bilateral salpingectomy 
 Documented bilateral oophorectomy 
For individuals with permanent infertility due to an alternative medical cause other than 
the above (eg, Mullerian agenesis, androgen insensitivity), Investigator discretion should 
be applied to determining study entry. 
Note: Documentation can come from the site personnel’s: review of the patient’s medical 
records, medical examination, or medical history interview. 

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Contraception Guidance: 
Female patients of childbearing potential should be informed that taking study intervention may 
involve unknown risks to the fetus (unborn baby) if a pregnancy were to occur during the study. 
Specifically, the study intervention may have adverse effects on a fetus in utero. 
See Inclusion Criterion 9 in Section 5.1 for study requirements for female and male patients. 
Patients with childbearing potential should use highly effective methods of contraception, 
defined as one that results in a low failure rate (ie, less than 1% per year) when used consistently 
and correctly are described in Table 14. These contraceptive methods must be used from 14 days 
prior to randomization and for at least 90 days after the last dose of study intervention. Patients 
must adhere to the contraception requirement for the duration of the study and during the follow-
up period to participate in the study. If there is any question that a patient will not reliably 
comply with the requirements for contraception, that patient should not be entered into the study. 
Note that some contraception methods are not considered highly effective (eg, male or female 
condom with or without spermicide; female cap, diaphragm, or sponge with or without 
spermicide; non-copper containing intrauterine device; progestogen-only oral hormonal 
contraceptive pills where inhibition of ovulation is not the primary mode of action [excluding 
Cerazette/desogestrel which is considered highly effective]; and triphasic combined oral 
contraceptive pills). 
Table 14 
Highly Effective methods of contraception (<1% failure rate) 
Barrier/Intrauterine methods 
Hormonal Methods 
 
Copper T intrauterine device 
 
Levonorgestrel-releasing intrauterine system 
(eg, Mirena®)a 
 
Implants: Etonogestrel-releasing implants: eg, 
Implanon® or Norplant® 
 
Intravaginal Devices: 
Ethinylestradiol/etonogestrel-releasing 
intravaginal devices: eg, NuvaRing® 
 
Injection: Medroxyprogesterone injection: eg, 
Depo-Provera® 
 
Combined Pill: Normal and low dose 
combined oral contraceptive pill 
 
Patch: Norelgestromin/ethinylestradiol-
releasing transdermal system: eg, Ortho 
Evra® 
 
Minipill: Progesterone based oral 
contraceptive pill using desogestrel: 
Cerazette® is currently the only highly 
effective progesterone-based pill 
a This is also considered a hormonal method 

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Collection of Pregnancy Information in female patients who become pregnant, and female 
partners of male patients 
 Please refer to the Study Manual for details on the pregnancy reporting procedure and 
associated report form
 The Investigator will collect pregnancy information on any female patient or partner of 
a male patient who becomes pregnant while participating in this study. Information 
will be recorded on the appropriate form and submitted to the Sponsor within 24 hours 
of learning of a patient's pregnancy.
 The patient will be followed to determine the outcome of the pregnancy. The 
Investigator will collect follow-up information on the patient and the neonate and the 
information will be forwarded to the Sponsor. Generally, follow-up will not be 
required for longer than 6 to 8 weeks beyond the estimated delivery date. Any 
termination of pregnancy will be reported, regardless of fetal status (presence or 
absence of anomalies) or indication for the procedure. 
 While pregnancy itself is not considered to be an AE or SAE, any pregnancy 
complication or elective termination of a pregnancy will be reported as an AE or SAE. 
A spontaneous abortion is always considered to be an SAE and will be reported as 
such. Any post-study pregnancy related SAE considered reasonably related to the 
study intervention by the Investigator will be reported to the Sponsor as described in 
Section 8.3.4. While the Investigator is not obligated to actively seek this information 
in former study patients, he or she may learn of an SAE through spontaneous 
reporting. 
 Any female patient who becomes pregnant while participating in the study will 
discontinue study intervention or be withdrawn from the study 

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10.5.
Appendix 5: Rating Scales
10.5.1.
Global cGVHD Activity Assessment – Clinician Report

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Source: Lee, 2015.

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10.5.2.
cGVHD mLSS
Please let us know if you have been bothered by any of the following problems in the last 7 days.
Subscale 
Name 
Items 
Not at 
all 
Slightly 
Moderately 
Quite a 
bit 
Extremely 
Skin
a.
Abnormal skin color
0
1
2
3
4
b.
Rashes
0
1
2
3
4
c.
Thickened skin
0
1
2
3
4
d.
Sores on skin
0
1
2
3
4
e.
Itchy skin
0
1
2
3
4
Eye
f.
Dry eyes
0
1
2
3
4
g.
Need to use eye drops 
frequently 
0 
1 
2 
3 
4 
h. Difficulty seeing clearly 
0 
1 
2 
3 
4 
Mouth 
i. 
Need to avoid certain foods due 
to mouth pain 
0 
1 
2 
3 
4 
j. 
Ulcers in mouth 
0 
1 
2 
3 
4 
Lung 
k. Frequent cough 
0 
1 
2 
3 
4 
l. 
Colored sputum 
0 
1 
2 
3 
4 
m. Shortness of breath at rest 
0 
1 
2 
3 
4 
n. Fevers 
0 
1 
2 
3 
4 
Nutrition 
o. Difficulty swallowing solid 
foods 
0 
1 
2 
3 
4 
p. Difficulty swallowing liquids 
0 
1 
2 
3 
4 
q. Vomiting 
0 
1 
2 
3 
4 
r.
Weight loss
0
1
2
3
4
Energy
s.
Shortness of breath with 
exercise 
0
1
2
3
4
t. 
Joint and muscle aches 
0 
1 
2 
3 
4 
u. Limited joint movement 
0 
1 
2 
3 
4 
v. Muscle cramps 
0 
1 
2 
3 
4 
w. Weak muscles 
0 
1 
2 
3 
4 
x. Loss of energy 
0 
1 
2 
3 
4 
y. Need to sleep more/take naps 
0 
1 
2 
3 
4 
Psych 
z. 
Depression 
0 
1 
2 
3 
4 
aa. Anxiety 
0 
1 
2 
3 
4 
bb. Difficulty sleeping 
0 
1 
2 
3 
4 
Source: Lee, 2002, Teh, 2020.

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10.6.
Appendix 6: Abbreviations
Abbreviation Term 
Description 
AE
Adverse Event
AIDS
Acquired Immune Deficiency Syndrome
ALP 
Elevation of Alkaline Phosphatase  
ALT 
Alanine Aminotransferase  
AST 
Aspartate Aminotransferase  
 
BUN 
Blood Urea Nitrogen  
cGVHD 
Graft Vs. Host Disease  
CPK 
Creatine Phosphokinase  
CNI 
Calcineurin Inhibitor 
CR 
Complete Response  
CrCl 
Creatinine Clearance  
CRF 
Case Report Form  
 
 
CSF-1 
Colony stimulating factor 1 
CSF-1R 
Colony stimulating factor 1 receptor 
DLT 
Dose Limiting Toxicity  
DOR 
Duration of Response  
ECG 
Electrocardiogram 
ECP 
Extracorporeal photopheresis 
ELISA 
Enzyme-linked immunosorbent assay 
EOT 
End of treatment 
FDA 
Food and Drug Administration  
FFS 
Failure Free Survival 
GGT 
Gamma-Glutamyl Transferase  
GLDH 
Glutamate Dehydrogenase  
GVL 
Graft versus leukemia 
HBV 
Hepatitis B Virus  
hCG 
Human Chorionic Gonadotropin  
HCV 
Hepatitis C Virus  
HEENT 
Head, Ears, Eyes Nose and Throat  

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Abbreviation Term 
Description 
HSCT 
Hematopoietic Stem Cell Transplantation  
IA
Interim analysis
ICF
Informed Consent Form 
IDMC 
Independent Data Monitoring Committee 
IHC 
Evaluated by Immunohistochemistry  
IL
Interleukin
INR
International Normalized Ratio 
ITT 
Intent-to-Treat  
IV 
Intravenous  
kg
Kilograms  
mAb 
IgG4 Monoclonal Antibody  
mTOR 
Mammalian target of rapamycin 
NIH 
National Institutes of Health  
NK 
Natural Killer  
ORR 
Overall Response Rate  
PCSS 
Pediatric cGVHD Symptom Scale 
PFT 
Pulmonary Function Test 
PK 
Plasma Pharmacokinetics  
PR 
Partial Response  
Q2W 
Every 2 weeks 
Q4W 
Every 4 weeks  
RBC 
Red Blood Cell  
SAE
Serious Adverse Event 
SAP 
Statistical analysis plan 
SoA 
Schedule of Activities  
TEAE 
Treatment Emergent Adverse Event 
TB 
Tuberculosis 
ULN 
Upper Limit of Normal  
WBC 
White Blood Cell 

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11.
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Product: Axatilimab
05 April 2023
Protocol Number: SNDX-6352-0504 Amendment 4.0 GLOBAL
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