An Open-Label Phase 1a/1b Dose Escalation and Expansion Cohort Study of SL-172154 (SIRPα-Fc-CD40L) in Combination With Azacitidine or With Azacitidine and Venetoclax for the Treatment of Subjects With Higher-Risk Myelodysplastic Syndrome (MDS) or Acute Myeloid Leukemia (AML)
Phase: PHASE1
Conditions: Acute Myeloid Leukemia, Myelodysplastic Syndromes
Sponsor: Shattuck Labs, Inc.

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Protocol Title: An Open-Label Phase 1a/1b Dose Escalation and Expansion 
Cohort Study of SL-
-Fc-CD40L) in Combination with Azacitidine 
or with Azacitidine and Venetoclax for the Treatment of Subjects with Higher-Risk 
Myelodysplastic Syndrome (MDS) or Acute Myeloid Leukemia (AML) 
Short Title: Phase 1a/1b Study of SL-172154 in Subjects with Higher-Risk Myelodysplastic 
Syndrome or Acute Myeloid Leukemia 
 
Protocol Identifying Number: SL03-OHD-104
Version Number: v5.0 
Study Phase: 1a/1b
Legal Registered Address: 
Shattuck Labs, Inc.
21 Alexandria Way, Suite, 200 
Durham, North Carolina 27709 
Regulatory Agency Identifier Number(s)
IND: 154736 
EudraCT: 2021-003255-42
Effective Date:  14 Mar 2024 
This document is the confidential property of Shattuck Labs. It contains proprietary information and 
is submitted to the clinical trial site for the sole purpose of reviewing and conduct of the named clinical 
trial. Reproduction, disclosure, or use of the submission or information contained therein in whole or 
part otherwise than for this purpose is prohibited unless Shattuck Labs provides prior written 
authorization for such reproduction, disclosure or use.  
 

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TABLE OF CONTENTS 
TABLE OF CONTENTS ................................................................................................................ 2
LIST OF TABLES .......................................................................................................................... 8
LIST OF FIGURES ........................................................................................................................ 9
LIST OF ABBREVIATIONS....................................................................................................... 10
STATEMENT OF COMPLIANCE .............................................................................................. 15
KEY TRIAL CONTACTS ........................................................................................................... 16
STUDY SCHEMA 1..................................................................................................................... 17
STUDY SCHEMA 2..................................................................................................................... 18
PROTOCOL SYNOPSIS ............................................................................................................. 19
1. 
BACKGROUND AND STUDY RATIONALE ................................................................... 29
1.1 
Bridging Innate and Adaptive Immunity ....................................................................... 29
1.2 
Myelodysplastic Syndrome............................................................................................ 30
1.3 
Acute Myeloid Leukemia (AML) .................................................................................. 31
1.4 
CD47 and CD40 Targeting in MDS/AML..................................................................... 32
1.5 
SL-172154...................................................................................................................... 34
1.5.1 
Mechanism of Action .............................................................................................. 34
1.5.2 
Summary of Nonclinical Data ................................................................................ 35
1.5.2.1 
Pharmacology Studies ..................................................................................... 35
1.5.2.2 
Toxicology Studies in Non-Human Primates.................................................. 36
1.5.2.3 
Toxicokinetic Studies ...................................................................................... 37
1.6 
Summary of Clinical Data.............................................................................................. 37
1.7 
Study Rationale .............................................................................................................. 39
1.8 
Potential Risks and Benefits........................................................................................... 40
1.8.1 
Potential Risks ........................................................................................................ 40
1.8.2 
Potential Benefits .................................................................................................... 43
2. 
STUDY OBJECTIVES AND OUTCOME MEASURES..................................................... 44
3. 
DESCRIPTION OF STUDY DESIGN ................................................................................. 47
3.1 
Dose Escalation Cohorts ................................................................................................ 48
3.1.1 
SL-172154 Monotherapy Dose Escalation............................................................. 49
3.2 
SL-172154 Dose Escalation in Combination Treatment Arms ...................................... 50 
3.2.1 
SL-172154 Administered with Azacitidine ............................................................ 50 
3.2.2 
SL-172154 Administered with Azacitidine and Venetoclax (Safety Run-In) ........ 51 

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3.3 
Dose Expansion Cohorts ................................................................................................ 53 
3.3.1 
Part A: SL-172154 Administered with Azacitidine in Subjects with Higher-Risk 
MDS 
53 
3.3.2 
Part B: SL-172154 Administered with Azacitidine and Venetoclax in Subjects with 
AML 
53
3.3.3 
Part C: SL-172154 Administered with Azacitidine in AML Subjects with TP53 
Gene Mutation/Deletion ........................................................................................................ 53
3.3.4 
Part D (Randomized Cohorts): SL-172154 with Azacitidine vs Azacitidine 
monotherapy in HR-MDS Subjects ....................................................................................... 54
3.4 
Selection of Recommended Phase 2 Dose (RP2D)........................................................ 54
3.5 
Evaluation of a Less Frequent Dosing Schedule............................................................ 54
3.6 
Definition of Dose-Limiting Toxicity............................................................................ 54
3.7 
Concomitant Medications, Treatments and Procedures................................................. 55
3.7.1 
Prohibited Medications or Treatments .................................................................... 56
3.7.2 
Medications To Be Used With Caution .................................................................. 56
3.7.3 
Prophylactic Premedication for Infusion-Related Reactions (IRR) (All Subjects) 57
3.7.4 
Prophylactic Premedication for Cytokine Release Syndrome (CRS)..................... 57
3.7.5 
Recommendations for Prophylaxis and Management of Tumor Lysis Syndrome 
(Subjects Receiving Venetoclax) ........................................................................................... 57
3.8 
Toxicity Management Guidelines for SL-172154 ......................................................... 59
3.8.1 
Management of Infusion-Related Reactions........................................................... 61
3.8.2 
Management of Cytokine Release Syndrome (CRS) .............................................. 64
3.8.3 
Management of Hepatotoxicity............................................................................... 69
3.8.4 
Management of Non-hematologic and Hematologic AEs Not Specified ............... 71
3.9 
Toxicity Management Guidelines for Azacitidine ......................................................... 71
3.10 Toxicity Management Guidelines for Azacitidine and Venetoclax ............................... 72
3.11 Participant Withdrawal of Consent ................................................................................ 72
3.12 Lost to Follow-up........................................................................................................... 72
3.13 Premature Termination or Suspension of the Study....................................................... 73
3.14 Study Treatment Discontinuation Criteria ..................................................................... 73
3.15 Duration of Follow-Up................................................................................................... 74
3.16
End of Study Definition ................................................................................................. 74
3.17 COVID-19 Risk Assessment.......................................................................................... 74
4. 
STUDY POPULATION ........................................................................................................ 74

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4.1 
Inclusion Criteria ............................................................................................................ 75 
4.2 
Exclusion Criteria ........................................................................................................... 78 
4.3 
Screen Failures ............................................................................................................... 80 
5. 
PHARMACEUTICAL PRODUCT INFORMATION .......................................................... 80 
5.1 
Investigational Product (SL-172154) ............................................................................. 80 
5.1.1 
Investigational Product Description ........................................................................ 80 
5.1.2 
Preparation, Handling, and Storage of SL-172154 ................................................. 81 
5.1.2.1 
Preparation ....................................................................................................... 81 
5.1.2.2 
Handling .......................................................................................................... 81 
5.1.2.3 
Storage ............................................................................................................. 81 
5.1.3 
Dosing and Change in Weight ................................................................................ 81 
5.1.4 
Monitoring Dose Administration ............................................................................ 82 
5.1.5 
Treatment of SL-172154 Overdose ........................................................................ 82 
5.2 
Azacitidine ..................................................................................................................... 83 
5.3 
Venetoclax ...................................................................................................................... 83 
5.4 
Drug Accountability and Treatment Compliance .......................................................... 84 
6. 
STUDY ASSESSMENTS AND PROCEDURES ................................................................ 85 
6.1 
Schedule of Assessments: SL-172154 Monotherapy Dose Escalation Cohorts Only ... 87 
6.1.1 
PK, ADA, and Cytokines Sampling Schedule (SL-172154 Monotherapy Dose 
Escalation Cohorts)................................................................................................................ 90 
6.2 
Schedule of Assessments: SL-172154 Combination Cohorts, Dose Escalation or Dose 
Expansion (SL-172154 with Azacitidine or Azacitidine and Venetoclax) ............................... 91 
6.2.1 
PK, ADA, and Cytokines Sampling Schedule (SL-172154 Combination Dose 
Escalation or Dose Expansion Cohorts) ................................................................................ 95 
6.3 
Schedule of Assessments: Dose Expansion Cohort Part D (SL-172154 in Combination 
with Azacitidine in Previously Untreated HR-MDS Subjects) ................................................. 96 
6.3.1 
PK, ADA, Receptor Occupancy, Complement analysis and Cytokines Sampling 
Schedule for Dose Expansion Cohort Part D (SL-172154 in Combination with Azacitidine 
in Previously Untreated HR-MDS Subjects) ......................................................................... 99 
6.4 
Schedule of Assessments: Dose Expansion Cohort Part D (Azacitidine Monotherapy in 
Previously Untreated HR-MDS Subjects)............................................................................... 100 
6.4.1 
Immunophenotying, Complement analysis and Cytokines Sampling Schedule for 
Dose Expansion Cohort Part D (Azacitidine Monotherapy in Previously Untreated HR-MDS 
Subjects) .............................................................................................................................. 104
6.5 
Demographics, Medical History, and Screening Assessments .................................... 104

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6.5.1 
Informed Consent.................................................................................................. 104
6.5.2 
Eligibility Criteria ................................................................................................. 104
6.5.3 
Subject Demographics .......................................................................................... 104
6.5.4 
Medical History .................................................................................................... 104
6.5.5 
Concomitant Medications..................................................................................... 104
6.5.6 
Documentation of TP53 Gene Mutation/Deletion (Applicable as Entry Criterion for 
AML Subjects Enrolled to Part C Dose Expansion Cohort and for HR-MDS Subjects 
Enrolled to Part D Dose Expansion Cohort) ....................................................................... 104
6.5.7 
Randomization ...................................................................................................... 105
6.6 
Safety Evaluations........................................................................................................ 105
6.6.1 
Physical Examination............................................................................................ 105
6.6.2 
ECOG Performance Status ................................................................................... 105
6.6.3 
Pulse Oximetry...................................................................................................... 105
6.6.4 
Vital Signs ............................................................................................................. 105
6.6.5 
Electrocardiogram ................................................................................................. 105
6.6.6 
Echocardiogram/Multigated Acquisition (MUGA) scans .................................... 105
6.6.7 
Local and Central Laboratory Assessments.......................................................... 106
6.6.7.1 
Ad Hoc Labs for IRR or CRS AEs ................................................................ 109
6.6.7.2 
Pregnancy Testing ......................................................................................... 109
6.6.7.3 
Blood Type and Screen (ABO/Rh) and DAT (except in Part D) .................. 109
6.7 
Pharmacokinetics ......................................................................................................... 109
6.8 
Anti-Drug Antibody and Neutralizing Antibody Assessment ..................................... 110
6.9 
Pharmacodynamic Assessments in Blood.................................................................... 110
6.9.1 
Cytokine and Chemokine Analysis....................................................................... 110
6.9.2 
Complement activation Analysis.......................................................................... 110
6.9.3 
Receptor Occupancy ............................................................................................. 110
6.10 Bone Marrow Assessments.......................................................................................... 110
6.10.1 
Bone Marrow Aspirate Sample for Disease Assessment (Local Laboratory)...... 113
6.10.2 
Bone Marrow Aspirate Sample (Central Laboratory) .......................................... 114
6.10.2.1 
Bone Marrow Aspirate for MRD Assessment by Flow Cytometry .............. 114
6.10.2.2 
Bone Marrow Aspirate for Molecular Genetic Profiling............................... 114
6.10.2.3 
Bone Marrow Aspirates for Receptor Occupancy Analyses (Dose Escalation 
and Dose Expansion cohorts; Parts A, B and C) ............................................................. 114 

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6.10.2.4
Bone Marrow Aspirate for Translational or Biomarker Research ................ 115
6.11 Transformation to Acute Myeloid Leukemia (Only for MDS Subjects) ..................... 115
6.12 Transfusion Assessment............................................................................................... 115
6.13 Information Collected at Post Treatment Visit and During Survival Follow-Up Period
 
116 
6.14 Unscheduled Visit ........................................................................................................ 116
7. 
SAFETY ASSESSMENTS ................................................................................................. 116
7.1 
Definitions for Safety Parameters ................................................................................ 117
7.1.1 
Events Not Qualifying as AE or SAE................................................................... 118
7.1.2 
Adverse Events Commonly Associated with AML or MDS Study Population 
and/or Progression of Disease ............................................................................................. 119
7.2 
Classification of an Adverse Event .............................................................................. 119
7.2.1 
Assessment of Severity ......................................................................................... 119
7.2.2 
Assessment of Causality ....................................................................................... 120
7.2.3 
Expectedness ......................................................................................................... 120
7.3 
Timing for Event Assessment and Follow-Up............................................................. 120
7.4 
Procedures for Recording and Reporting of Adverse Events ...................................... 121
7.5 
Reporting of Pregnancy................................................................................................ 122
7.6 
Reporting of Overdose, Misuse of IP, or Suspected Transmission of Infectious Agent
 
122
7.7 
Study Halting Rules ..................................................................................................... 122
7.8 
Safety Oversight........................................................................................................... 122
8. 
EFFICACY ASSESSMENTS ............................................................................................. 123
8.1 
Bone Marrow Aspirate for Disease Assessment .......................................................... 123
8.1.1 
AML Response Criteria........................................................................................ 123
8.1.2 
MDS Response Criteria ........................................................................................ 125
9. 
DATA ANALYSIS AND STATISTICAL CONSIDERATIONS...................................... 128
9.1 
Study Design and Sample Size Determination ............................................................ 128
9.1.1 
Dose Escalation Cohorts and Safety Run-In Cohort............................................. 128
9.1.2 
Dose Expansion .................................................................................................... 131
9.1.3 
Sample Size Determination................................................................................... 133
9.2 
Statistical Analyses ...................................................................................................... 133
9.2.1 
Analysis Populations ............................................................................................. 134

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9.2.2 
Data Analysis During Dose Escalation and Safety Run-In .................................. 134
9.2.3 
General Data Analysis and Consideration ............................................................ 135
9.2.4 
Safety Analyses ..................................................................................................... 135
9.2.5 
Efficacy Analyses ................................................................................................. 135
9.2.6 
Pharmacokinetics .................................................................................................. 137
9.2.7 
Immunogenicity Analysis..................................................................................... 138
9.2.8 
Pharmacodynamics Analyses................................................................................ 138
10. CLINICAL MONITORING ................................................................................................ 138
11. SOURCE DOCUMENTS AND ACCESS TO SOURCE DATA AND DOCUMENTS ... 139 
11.1 Source Data .................................................................................................................. 139
11.2 Access to Data.............................................................................................................. 139
11.3 Data Recording and Record Keeping ........................................................................... 139
12. QUALITY ASSURANCE PROCEDURES........................................................................ 139
13. ETHICS / PROTECTION OF HUMAN SUBJECTS ......................................................... 140
13.1 Ethical Standard ........................................................................................................... 140
13.2 Institutional Review Board / Independent Ethics Committee...................................... 140
13.3 Informed Consent Process............................................................................................ 140
13.3.1 
Consent/Assent and Other Informational Documents Provided to the Subjects .. 140 
13.3.2 
Consent Procedures and Documentation .............................................................. 141 
13.4 Participant and Data Confidentiality ............................................................................ 141
13.4.1 
Research Use of Stored Human Samples, Specimens, or Specimen Data ............ 142
14. DATA HANDLING AND RECORD KEEPING............................................................... 142
14.1 Communication and Data Dissemination Plan............................................................. 142
14.2 Data Collection and Management Responsibilities ..................................................... 142
14.3 Study Record Retention ............................................................................................... 143
14.4 Protocol Deviations...................................................................................................... 143
14.5 Publications and Data Sharing Policy.......................................................................... 144
15. LITERATURE REFERENCES .......................................................................................... 145 
16. Appendices .......................................................................................................................... 151 
16.1 Revised International Prognostic Scoring System (IPSS-R) for MDS ........................ 151 
16.2 2017 ELN Risk Stratification by Genetics (AML) ...................................................... 152 
16.3 Contraception Requirements ........................................................................................ 153 

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16.4 Recommendations for Initial Management of Electrolyte Imbalances and Prevention of 
Tumor Lysis Syndrome (TLS) ................................................................................................ 155 
16.5 Recommendation for Toxicity Management of Cytopenias for Azacitidine Combination 
Regimen .................................................................................................................................. 157 
16.6 Recommendation for Toxicity Management of Cytopenias for Venetoclax and 
Azacitidine Combination Regimen ......................................................................................... 159 
16.7 Recommendation for the Management of Potential Venetoclax Interactions with 
CYP3A and P-gp Inhibitors .................................................................................................... 160 
16.8 ECOG Performance Status Criteria.............................................................................. 160 
16.9 Cockcroft-Gault Formula for Creatinine Clearance ..................................................... 161 
16.10 Summary of Changes for Protocol Amendment 01 ..................................................... 162 
16.11 Summary of Changes for Protocol Amendment 02 ..................................................... 173 
16.12 Summary of Changes for Protocol Amendment 03 ..................................................... 184 
16.13 Summary of Changes for Protocol Amendment 3.1 .................................................... 190 
16.14 Summary of Changes for Protocol Amendment 3.2 .................................................... 191 
16.15 Summary of Changes for Protocol Amendment 4.0 .................................................... 192 
16.16 Summary of Changes for Protocol Amendment 5.0 .................................................... 196 
 
LIST OF TABLES 
Table 1  
SL-172154 Monotherapy Dosing ............................................................................... 49 
Table 2  
SL-172154 Administered with Azacitidine ................................................................ 51 
Table 3 
SL-172154 Administered with Azacitidine and Venetoclax ...................................... 52 
Table 4 
Tumor Lysis Syndrome Classification ....................................................................... 59 
Table 5 
SL-172154 Dose Reduction for Management of Toxicities ....................................... 60 
Table 6 
ASTCT Consensus Grading Criteria for CRS ............................................................ 64 
Table 7 
Azacitidine Dosing During Cycles 1 and 2 ................................................................ 83 
Table 8 
Azacitidine Dosing During Cycle 3 and Thereafter ................................................... 83 
Table 9 
Venetoclax Dosing During Cycles 1 and 2 ................................................................ 84 
Table 10 
Venetoclax Dosing During Cycle 3 and Thereafter ................................................... 84 
Table 11 
PK, ADA, Blood Receptor Occupancy, and Cytokines Sampling Schedule 
(SL-172154 Monotherapy Cohorts) .............................................................................................. 90 
Table 12 
PK, ADA, Blood Receptor Occupancy, and Cytokines Sampling Schedule 
(SL-172154 Combination Cohorts) .............................................................................................. 95 

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Table 13 
PK, ADA, Receptor Occupancy, Complement analysis, and Cytokine Sampling 
Schedule Part D (SL-172154 in Combination with Azacitidine) ................................................. 99
Table 14 
Immunophenotyping, Complement analysis, and Cytokine Sampling Schedule Part D 
(Azacitidine monotherapy) ......................................................................................................... 104
Table 15 
Bone Marrow Assessment for SL-172154 Monotherapy......................................... 111
Table 16 
Bone Marrow Assessment Schedule for SL-172154 in Combination with Azacitidine 
or Azacitidine and Venetoclax (Dose Escalation and Dose Expansion cohorts; Parts A, B and C)
 
112 
Table 17 
Bone Marrow Assessment Schedule for SL-172154 in Combination with Azacitidine 
or Azacitidine Monotherapy Treatment (Dose Expansion cohorts and Part D)......................... 113
Table 18
Dose Escalation Decision Rules for Each Dose Level Based on mTPI-2................ 130
Table 19
Operating Characteristics of mTPI-2 Design Based on 10000 Simulations ............ 131
Table 20
Response Rate and 90% CI Out of 20 Subjects........................................................ 132
Table 21
Serum SL-172154 PK Parameters............................................................................ 137
LIST OF FIGURES
Figure 1 
SIRP -Fc-CD40L (SL-172154) Mechanism of Action ............................................. 34
Figure 2 
SL-172154 Monotherapy............................................................................................ 49
Figure 3 
SL-172154 in Combination with Azacitidine............................................................. 50
Figure 4 
SL-172154 in Combination with Azacitidine and Venetoclax................................... 51
Figure 5 
Hematologic Recovery Requirements for CR, CRh, and CRi ................................. 125

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Trademark Information
Trademarks of Shattuck Labs, Inc.
Trademarks not owned by Shattuck Labs, Inc.
Agonist Redirected Checkpoint (ARC™) FluroTec®
VIDAZA®
VENCLEXTA® 

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STATEMENT OF COMPLIANCE 
The trial will be conducted in accordance with the protocol and the International Council for 
Harmonisation (ICH) Good Clinical Practice (GCP) Guidelines, and applicable Federal 
Regulations on the Protection of Human Subjects, and consistent with the consensus ethical 
principles derived from international guidelines including the Declaration of Helsinki and Council 
for International Organizations of Medical Sciences International Ethical Guidelines. The 
Principal Investigator will assure that no deviation from, or changes to the protocol will take place 
without prior agreement from the Sponsor and documented approval from the Institutional Review 
Board (IRB)/Independent Ethics Committee (IEC), except where necessary to eliminate an 
immediate hazard(s) to the trial participants. All personnel involved in the conduct of this study 
have completed Human Subjects Protection Training.
I agree to ensure that all staff members involved in the conduct of this study are informed about 
their obligations in meeting the above commitments.
Principal Investigator:
________________________________       ___________________________________
Print/Type Name
Signature
Date: ______________
 

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KEY TRIAL CONTACTS
Medical Monitor Name and Contact Information is provided in the Study Contact List. 
Sponsor Signatory: 
Date
 

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a. morphologically confirmed diagnosis of MDS by 2016 WHO criteria [Arber, 2016] with <20% blasts in 
bone marrow per bone marrow biopsy/aspirate or peripheral blood. 
b. confirmation of intermediate, high or very high risk category by Revised International Prognostic 
Scoring System (IPSS-R).  
Subjects with a diagnosis of any of the following are excluded: Atypical CML, juvenile myelomonocytic 
leukemia (JMML), chronic myelomonocytic leukemia (CMML), and unclassifiable MDS/ 
myeloproliferative neoplasm (MPN). 
5. [Dose Escalation Cohort – SL-172154 Monotherapy] Subjects with AML must have relapsed/refractory 
disease ( 5% blasts by manual aspirate differential, flow cytometry, or immunohistochemistry) following 
at least 1 prior line of therapy but no more than 4 prior lines of therapy. Subjects with higher-risk MDS 
must have relapsed/refractory disease following at least 1 prior line but no more than 4 prior lines of 
therapy. 
a. Prior hydroxyurea or other supportive care in the form of transfusions or growth factors will not be 
considered prior therapy. 
b. Subjects who have undergone allogeneic-hematopoietic cell transplantation (HCT) are eligible if they 
are at least 6 months post-HCT, have relapsed AML or MDS as defined above, are not on treatment or 
prophylaxis for graft versus host disease (GVHD) for at least 6 weeks before administration of study 
treatment, and have no active GVHD. 
c. Subjects must not be eligible for rescue chemotherapy and allogeneic-HCT per local or institutional 
guidelines at the time of screening. 
6. [Dose Escalation Cohort – SL-172154 Administered with Azacitidine] Subjects with relapsed/refractory 
AML and MDS (as defined in Inclusion criterion 5) following at least 1 prior line of therapy but no more 
than 4 prior lines of therapy. 
a. Treatment for MDS preceding secondary AML will not be considered as a prior line of therapy for 
secondary AML. 
b. Prior hydroxyurea or other supportive care in the form of transfusions or growth factors will not be 
considered prior therapy. 
c. Subjects who have undergone allogeneic-HCT are eligible if they are at least 6 months post-HCT, have 
relapsed AML or MDS as defined above, are not on treatment or prophylaxis for GVHD for at least 6 
weeks before the first dose of study treatment, and have no active GVHD. 
d. Subjects must not be eligible for rescue chemotherapy and allogeneic-HCT per local or institutional 
guidelines at the time of screening. 
In addition, previously untreated subjects meeting either of the following criteria are eligible for this cohort: 
a. Previously untreated subjects with AML with known adverse cytogenetics who fall into the adverse 
ELN risk group and who are unlikely to benefit from standard intensive induction therapy or refuse 
intensive induction therapy at time of enrollment. 
b. Previously untreated subjects with MDS with documentation of at least one TP53 gene mutation or 
deletion based on a local test. Prior MDS therapy with lenalidomide or other supportive care in the form 
of transfusions or growth factors is allowed. 
7. [Dose Expansion Cohort Part A: SL-172154 Administered with Azacitidine] Subjects diagnosed with MDS 
must be previously untreated. Prior MDS therapy with lenalidomide, luspatercept or supportive care in the 
form of transfusions or growth factors is allowed. Up to 1 cycle of prior therapy with a hypomethylating 
agent is permitted. Subjects with newly diagnosed treatment-related MDS are also eligible for enrollment. 
8. [Dose Escalation – Safety Run-in Cohort AND Dose Expansion Cohort Part B: SL-172154 Administered 
with Azacitidine and Venetoclax] Subjects with AML must be previously untreated as defined by: 
a. Subject must be ineligible for induction therapy with a standard cytarabine and anthracycline induction 
regimen due to age or co-morbidities as defined by the following:  
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required by local prescribing information after the last dose of azacitidine (i.e., for sites in UK, at least 3 
months; for sites in Canada, at least 6 months).
16. [Dose Expansion Cohort Part D: SL-172154 with Azacitidine vs Azacitidine monotherapy]: Subjects 
diagnosed with MDS must be previously untreated. Prior MDS therapy with lenalidomide, luspatercept or 
supportive care in the form of transfusions or growth factors is allowed. No prior therapy with a 
hypomethylating agent is permitted. Subjects with newly diagnosed treatment-related MDS are also 
eligible for enrollment. TP53 mutation status results based on local test must be available prior to 
randomization. 
Exclusion Criteria
Participants are excluded from the study if any of the following criteria apply: 
1. [Monotherapy and Combination Regimen Dose Escalation Cohorts] Prior treatment with:  
 CAR-T cell therapy within 3 months from the first dose of the study drug. 
 Prior treatment with anti-CD47 targeting agent or CD40 agonist within 28 days prior to the first dose of 
study treatment.  
 Prior treatment with signal-
-targeting agent. 
 Other experimental therapies for AML or MDS within 14 days or at least 5 half-lives (whichever is 
shorter) prior to the first dose of study treatment. 
2. Evidence of active CNS involvement with leukemia. 
3. Subjects requiring agents other than hydroxyurea to control blast counts within 14 days prior to the first 
dose of study treatment. 
4. Evidence of active bleeding or bleeding diathesis or major coagulopathy (including familial). 
5. [Only for Cohorts Including Venetoclax in the Regimen] Subject has received strong and/or moderate 
CYP3A inducers within 7 days prior to the first dose of venetoclax. 
6. Use of systemic corticosteroids (>10 mg daily of prednisone or equivalent) or other non-steroidal 
immunosuppressive medication, current or within 14 days of the first dose of study treatment with the 
following exceptions (i.e., the following are allowed within 14 days of first dose): 
 Topical, intranasal, inhaled, ocular, intraarticular corticosteroids 
 Physiological doses of replacement steroid (e.g., for adrenal insufficiency)  
 Steroid premedication for hypersensitivity reactions (e.g., reaction to IV contrast) or a brief course of 
treatment of non-autoimmune conditions (e.g., transfusion reactions, delayed-type hypersensitivity 
reaction caused by contact allergen). 
7.
Receipt of live attenuated vaccine within 30 days of first dose of SL-172154 treatment.
8. Subject has active, uncontrolled infection (e.g., viral, bacterial, or fungal). Subjects are eligible if infection 
is controlled with antibiotics, antivirals and/or antifungals. 
9.
[Only for Cohorts Including Venetoclax in the Regimen] Subject has a malabsorption syndrome or other 
condition that precludes the enteral route of administration.  
10. Subjects with:  
 
Symptomatic peptic ulcer disease or gastritis,  
 
active diverticulitis,  
 
other serious gastrointestinal disease associated with diarrhea within 6 months of first dose of 
study treatment. 
11. Clinically significant or uncontrolled cardiac disease including any of the following: 
 Myocarditis 
 Unstable angina within 6 months from first dose of study treatment 
 Acute myocardial infarction within 6 months from first dose of study treatment  
 Uncontrolled hypertension 
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Clinically significant (symptomatic) cardiac arrhythmias (e.g., sustained ventricular tachycardia, 
second- or third- degree atrioventricular (AV) block without a pacemaker, circulatory collapse requiring 
vasopressor or inotropic support, or arrhythmia not stabilized on therapy) 
12. Subject has chronic respiratory disease that requires continuous oxygen, or significant history of renal, 
neurologic, psychiatric, endocrinologic, metabolic, immunologic, hepatic, cardiovascular disease, or any 
other medical condition that in the opinion of the Investigator would adversely affect his/her participation 
in the study. 
13. Subjects who have had any major surgical procedure within 14 days of first dose of study treatment.
14. Subject is a woman who is pregnant or breast feeding or planning to become pregnant or breast feed while 
enrolled in this study. 
15. Psychiatric illness/social circumstances that would limit compliance with study requirements and 
substantially increase the risk of AEs or compromised ability to provide written informed consent. 
16. Presence of another malignancy that requires active therapy and that in the opinion of the Investigator and 
Sponsor would interfere with the monitoring of disease assessments in this study.  
17. Known hypersensitivity to any of the study medications including excipients of azacitidine.  
18. Has undergone solid organ transplantation. 
19. Known or active human immunodeficiency virus (HIV) infection 
20. Known or active infection with hepatitis B (positive for hepatitis B surface antigen [HbsAg]) or hepatitis C 
virus ([HCV]; if HCV antibody (Ab) test is positive check for HCV ribonucleic acid [RNA]).  
NOTE: Hepatitis B virus (HBV): Subjects who are hepatitis B core antibody [HbcAb]-positive but HbsAg-
negative are eligible for enrollment. HCV: Subjects who are HCV Ab-positive but HCV RNA-negative are 
eligible for enrollment. 
Safety Oversight 
During the study while subjects are receiving treatment with SL-172154, SMC meetings will be held to review 
relevant data with the Investigators or designees. These meetings will be held once a month (or more frequently if 
required) to review and discuss safety data and communicate results of ongoing analyses during dose escalation 
and dose expansion provided subjects have been enrolled and data are available to be reviewed. All available 
safety, PK, PD, and clinical outcome data for all subjects at the time of the scheduled SMC meeting will be 
reviewed and summarized. Attendees of SMC meetings will include, but not limited to, clinical Investigators (or 
designees), the Sponsor Medical Monitor and Statistician. The SMC will operate in accordance with the SMC 
charter which will define roles and accountabilities and the process for safety review. All dose escalation or 
safety decisions made by the SMC will be documented in writing with copies maintained at each site and the 
Trial Master File at the Contract Research Organization. 
Statistical Analyses 
The safety evaluation will be based on the All-Treated Population defined as all subjects who received at least 
one dose of study treatment. Frequency tables by dose levels will be used to describe safety and tolerability 
parameters such as: AEs, serious adverse events (SAEs), fatal AEs, AEs leading to dose reduction of SL-172154, 
and AEs leading to discontinuation of SL-172154, azacitidine and venetoclax. Changes in toxicity grade for 
laboratory parameters will also be summarized. AEs will be mapped to a Medical Dictionary for Regulatory 
Activities (MedDRA) preferred term and system organ classification. All AEs except CRS will be graded 
according to the NCI CTCTAE v5.0. CRS will be graded per the ASTCT Consensus Grading Criteria for CRS. 
The DLT evaluation will be based on the DLT-evaluable population [defined as all subjects enrolled in the dose 
escalation cohorts (SL-172154 monotherapy or SL-172154/azacitidine combination) or safety run-in cohort (SL-
172154, azacitidine and venetoclax combination) who receive at least 2 of 4 scheduled doses of SL-172154 and at 
least 50% of the scheduled doses of the combination agent (azacitidine or venetoclax) and complete the safety 
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will be summarized by dose level for monotherapy dose escalation cohorts, combination dose escalation cohorts,
and the safety run-in cohort. The MTD will be estimated using isotonic regression.
For dose escalation and Part A, B and C of dose expansion, anti-tumor efficacy data will be summarized by dose 
level and overall for MDS and AML, respectively, in the All Treated population and Response-Evaluable 
population (defined as Subjects in the All Treated Population who have a baseline disease assessment and have at 
least one post-baseline disease assessment or have progressed or died before the first post-baseline disease 
assessment). For Part D of dose expansion, efficacy analysis will be based on Intent-to-treat (all randomized 
subjects regardless of whether or not treatment was administered), All Treated and response evaluable population. 
All efficacy data will be summarized by the treatment arm. The CR rate and 95% CI in each arm will be 
calculated and CR rate will be compared between SL-172154 1.0 m/g/kg or 3.0 mg/kg in combination with 
azacitidine and azacitidine monotherapy using Fisher’s exact test, 95% CIs for the difference in CR rate will be 
calculated. 
The primary analysis is based on Investigator-assessed response per 2006 IWG criteria for subjects with MDS or 
per 2017 ELN criteria for subjects with AML. The ORR, CR, composite CR, CR/CRh, RBC and platelet 
transfusion independence rate and MRD-negative response rate will be estimated along with a 95% confidence 
interval using the exact probability method. DOR and time to response will be evaluated, using the Kaplan-Meier 
method, for the subgroup of subjects with CR, composite CR, CR/CRh, or ORR. Duration of RBC and platelet 
transfusion independence will be evaluated, using the Kaplan-Meier method, for the subgroup of subjects with 
transfusion independence. The Kaplan-Meier method will be used to estimate the PFS/EFS/OS curve and 
PFS/EFS/OS rate at timepoint of interest. 
SL-172154 PK parameters will be summarized and analyzed using appropriate statistical methods. The 
relationship between PK exposure parameters and ADA, safety, efficacy, and PD outcome measures may be 
explored, as data permit, using appropriate graphical and statistical methods. PD biomarkers values will be 
summarized descriptively by dose level and visit. The effect of ADA on PK, PD, safety and efficacy will be 
explored, as data permit, using appropriate graphical and statistical methods. 
 

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1.
 BACKGROUND AND STUDY RATIONALE
1.1
Bridging Innate and Adaptive Immunity 
Cluster of differentiation (CD) 47 is expressed by many somatic and hematopoietic tissues and is 
an important protective mechanism to prevent red blood cell (RBC) and platelet destruction by 
macrophages and splenic CD4+ dendritic cells (DCs) [Oldenborg, 2000; Blazar, 2001; Yamao, 
2002; Olsson, 2005; Yi, 2015]. The anti-
of this axis as the macrophage ‘do not eat me’ signal. The ‘eat me’ signal which ultimately leads 
to red blood cell (RBC) destruction by splenic DCs is dependent upon a second activating signal, 
including CD18 containing integrins [Yi, 2015]. Uncoupling of the ‘do not eat me’ and ‘eat me’ 
signals likely increases the fitness of the host by providing improved regulation for erythrocyte 
Abundant expression of CD47 in many hematogenous and solid tumors led to investigation of 
whether tumor cells had co-opted this pathway as a protective mechanism against immune 
mediated destruction. Early studies hypothesized that the role of CD47 as a ‘do not eat me’ signal 
by macrophages for erythrocyte homeostasis would also explain the observed anti-tumor benefit 
-Fc fusion proteins [Chao, 2012; 
Willingham, 2012; Weiskopf, 2013]. More recent studies, however, have clarified that DCs are an 
[Liu, 2015]. 
phagocytosed tumor mitochondrial DNA, which initiates a cyclic guanine monophosphate – 
adenosine monophosphate synthase/stimulator of interferon genes (cGAS/STING) mediated type 
I interferon response that facilitates cross-presentation of tumor antigens to CD8+ T cells [Liu, 
2015; Xu, 2018]. Increased antigen priming of CD8 + DCs 
inhibition dramatically enhances tumor rejection in multiple preclinical tumor models, 
 
for anti-tumor immunity [Hildner, 2008]
-tumor immunity 
is due to the specialized ability of these antigen presenting cells (APC) to cross-present exogenous 
tumor antigens. Following phagocytosis, these tumor antigens gain entry to the DC cytosol and 
then are cross-presented to CD8+ T cells. CD40 ligation by CD40 ligand (CD40L), expressed by 
DCs 
-), is an important signal for enhancing the antigen cross-
presenting activity of exogenous antigen by DCs to CD8+ T cells [Bennett, 1998; Schoenberger, 
1998; O'Connell, 2000; Delamarre, 2003; Yasumi, 2004]. Interestingly, activation of tumor 
necrosis factor receptor-associated factor (TRAF) signaling downstream of CD40 ligation has also 
been shown to facilitate a type I interferon response via STING activation, but STING activation 
does not appear to be essential for the anti-tumor immune response to CD40 stimulation [Yao, 
2016]. Despite the potentially context-dependent role of a type I interferon response, anti-tumor 
immunity to CD40 agonists remained dependent upon batf3-positive DCs and CD8+ T cells . 

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innate and adaptive immunity; however, the two pathways appear to have distinct dependence 
upon a type I interferon response. 
1.2 
Myelodysplastic Syndrome 
Myelodysplastic syndromes (MDS) is a heterogeneous group of clonal stem cell disorders 
characterized by ineffective hematopoiesis resulting in cytopenias in at least one hematologic 
lineage and a risk of evolution to acute myeloid leukemia (AML) [Cazzola, 2020]. Variable 
degrees of cytopenias result in a high symptom burden with a risk of death from complications 
and transformation to AML. The median age at diagnosis of MDS is ~ 70 years. Based on the 
SEER–Medicare database the incidence of MDS is estimated as high as 75 per 100,000 persons 
aged 65 years [Cogle, 2011]. With the current demographic trend, both incidence and prevalence 
is expected to grow.
The Revised International Prognostic Scoring System (IPSS-R) is used to estimate the risk of 
evolution to AML and expected survival. IPSS-R considers the number and degree of cytopenias, 
proportion of blasts in the marrow, and the risk of specific cytogenetic abnormalities. IPSS-R 
defines 5 major prognostic categories: very low, low, intermediate, high, and very high risk. In 
clinical practice, a cut-off IPSS-R score of 3.5 distinguishes patients between lower-
median survival of 5.9 years) and higher-risk MDS (score > 3.5; median survival of 1.5 years). 
Lower-risk and higher-risk MDS accounts for approximately two-thirds and one-third, 
respectively, of all cases at onset of disease [Pfeilstocker, 2016].
Molecular profiling can improve risk stratification and substantially inform clinical decision 
making [Cazzola, 2020]. Mutations in SF3B1, TET2, SRSF2, ASXL1, DNMT3A, and RUNX1 
occur in at least 10% of patients who have MDS, with a long list of additional genes that are 
mutated less frequently. TP53, NRAS, ASXL1, and EZH2 mutations are consistently associated 
with poor outcomes while SF3B1 mutations are associated with more favorable outcomes. Patients 
with therapy-related MDS frequently have TP53 mutations or PPM1D mutations and a complex 
karyotype. Biallelic defects in TP53 predicts a risk of leukemic transformation and death 
independent of IPSS-R score. The deletion on the long arm of chromosome 5 is the initiating driver 
mutation that leads to haploinsufficiency of multiple genes and, in turn, to clinical manifestations. 
Some patients with MDS have features of myeloproliferative diseases associated with an over-
representation of mutations such as JAK2, SRSF2, SETBP1, CSF3R, and BCOR compared with 
those without these features. 
Not all MDS patients need to be treated immediately upon diagnosis. When treatment is required, 
the main objective is to ameliorate cytopenias, primarily anemia, and improve the quality of life. 
For patients with higher-risk MDS, treatment is aimed not only at ameliorating cytopenias but also 
at preventing evolution to AML and thus prolonging survival. Allogeneic-hematopoietic cell 
transplantation (HCT), is the only potentially curative treatment. However, the morbidity and 
mortality associated with the allogeneic-HCT in older adults with comorbid diseases precludes 
this as a viable option for many. Several drugs can modulate myelodysplastic hematopoiesis, but 
available treatments fail to eradicate it, mainly because selective pressure leads to the emergence 
of resistant subclones. The use of a hypomethylating agent, azacitidine or decitabine, currently 
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transplantation. About half the patients treated with azacitidine have a hematologic response, 
including some with a complete response. Treatment is associated with prolonged survival 
[Fenaux, 2009], although the survival benefit observed in real-life studies is on the order of a few 
months [Ozbalak, 2012]. 
1.3
Acute Myeloid Leukemia (AML) 
AML is a heterogeneous disease characterized by acquired genetic alterations in hematopoietic 
progenitor cells. AML is defined by the World Health Organization (WHO) as a myeloid neoplasm 
with 20% or more blasts in the peripheral blood or bone marrow [Vardiman, 2002]. The 
pathogenesis involves an abnormal proliferation and differentiation of a clonal population of 
myeloid stem cells. The estimated number of new cases in the United States is 19,940 and the 
number estimates deaths is 11,180. Per SEER database (accessed 18 January 2021, 
https://seer.cancer.gov/statfacts/html/amyl.html), the median age of diagnosis is 68 years with 
approximately one-third of patients being diagnosed over the age of 75. More than 70% of patients 
65 years or older will die of their disease within 1 year of diagnosis. 
Prognostic risk is defined at diagnosis based on certain cytogenetic and molecular aberrations 
[Dohner, 2017]. Well characterized chromosomal translocations result in the formation of chimeric 
proteins which alter the normal maturation process of myeloid precursor cells. In addition to 
chromosomal translocations, genetic mutations (e.g., NPM1, CEBPA, RUNX1, FLT3, IDH1, 
IDH2, K/NRAS, TP53, ASXL1, c-KIT) are identified often in the absence of translocations. 
Alterations in genes involved in epigenetic regulation (DNMT3A, ASXL1, TET2) and less 
frequently in splicing factor genes (SF3B1, SRSF2), have emerged as another class of mutations 
with downstream effects on cellular differentiation and proliferation.  
Although advances in the treatment of AML have led to significant improvements in outcome for 
younger patients, the prognosis in the elderly remains poor. Standard treatment for the medically 
fit, newly diagnosed AML patient consists of remission induction therapy with cytarabine 
combined with an anthracycline, usually daunorubicin or idarubicin (7 + 3). Induction therapy is
followed by consolidation therapy. Allogeneic stem cell transplantation can be curative for some 
patients with AML. A therapeutic graft-versus-leukemia effect ensues in which donor-derived T
cells recognize the minor histocompatibility antigens expressed on host leukemia cells. 
Unfortunately, only a minority of patients are candidates for stem cell transplantation, but the 
success of this procedure suggests that other immune strategies may be beneficial in AML. Higher 
proportion of unfavorable cytogenetics, higher frequency of antecedent hematologic disorders or 
prior therapy for previous malignancies, and more frequent expression of the multidrug resistance 
phenotype account for the poor outcomes associated with current therapy.  
AML in elderly patients is a biologically and clinically distinct disease. The presence and severity 
of comorbid conditions, compromised end organ function that enhance the toxicity of induction 
chemotherapy, and limitations in functional capacity all decrease the ability for the elderly patient 
to tolerate induction chemotherapy and survive life-threatening infections often associated with 
AML therapy. While some elderly patients are able to receive standard induction or intensive 
chemotherapy, the majority are treated with less intensive therapies such as hypomethylating 
agents or low dose cytarabine. In a recent clinical trial, overall survival (OS) was longer and the 

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incidence of remission was higher among AML patients who received azacitidine plus venetoclax 
compared to those who received azacitidine alone [DiNardo, 2020b]. This regimen is being 
adopted as the new standard of care in previously untreated patients who are ineligible for intensive 
chemotherapy.  
Nonetheless, the benefit of improved median OS from the combination of azacitidine and 
venetoclax has not been observed in TP53-mutated AML patients. No benefit in OS was observed 
in this poor prognostic subgroup although an increase in objective response rate (ORR) was 
observed (55% vs. 0% in patients treated by the combination of azacitidine and venetoclax vs. the 
combination of azacitidine and placebo, respectively) [DiNardo, 2020b; Cluzeau, 2021]. This is in 
line with other retrospective cohorts of TP53-mutant AML patients treated with decitabine, another 
hypomethylating agent, and venetoclax. Despite use of extended decitabine courses, these cohorts 
demonstrated a median OS of approximately 6 months regardless of venetoclax receipt [Maiti, 
2019; DiNardo, 2020b; Venugopal, 2021]. These clinical findings are supported by recent 
mechanistic observations identifying TP53 mutation to be a direct driver of venetoclax resistance 
[Nechiporuk, 2019; DiNardo, 2020c]. In total, these data demonstrate that the addition of 
venetoclax to azacitidine has not provided a significant improvement for AML patients with TP53 
mutation, and thus the investigation of novel agents in combination with azacitidine is warranted.
1.4
CD47 and CD40 Targeting in MDS/AML
CD47 is upregulated in hematopoietic stem cells and leukemia cells [Jaiswal, 2009]. Increased 
expression of CD47 is observed on CD34+CD38–CD90–Lin–leukemia stem cells compared to 
normal CD34+CD38–CD90+Lin– hematopoietic stem cell counterparts. The expression of CD47 
increases from low- to high-risk MDS and to AML and may represent a key event in the 
transformation from preleukemic to leukemic state [Pang, 2013]. In AML, high CD47 expression 
at diagnosis is associated with a significantly worse event-free and OS [Majeti, 2009]. 
Immune evasion is a barrier to effective immunotherapy in AML. Acute myeloid leukemia 
activates immune regulatory mechanisms to avoid immune mediated elimination. These 
mechanisms include the expression of checkpoint ligands, such as CD47, programmed cell death 
ligand-1 (PD-L1), and galectin 9 (Gal-9), poliovirus receptor and poliovirus receptor-related 2 
(PVR/PVRL2), T cell immunoreceptor with Ig and ITIM domains (TIGIT) on AML cells, and 
expansion of regulatory T cells and myeloid-derived suppressor cells [Vadakekolathu, 2017; 
Lamble, 2020; Vadakekolathu, 2020]. Immune-infiltrated and immune-depleted profiles in the 
Immune landscape of AML may also predict chemotherapy resistance and immunotherapy 
response [Vadakekolathu, 2020]. Additionally, TP53 mutated AML correlates with an immune-
infiltrated tumor microenvironment and high levels of actionable immune checkpoints [Sallman, 
2020b; Vadakekolathu, 2020].  
A number of leukemia-associated antigens have been identified in AML. These antigens, however, 
are typically expressed in other tissues including the thymus. T cells capable of recognizing these 
antigens are most likely deleted via mechanisms of central tolerance thus leaving behind low-
affinity T cells which elicit an ineffective immune response. AML also has a low mutational 
burden thus resulting in a paucity of neoantigens for presentation to T cells [Beyar-Katz, 2018].  

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In an AML animal model, leukemia specific CD8 T cells undergo abortive proliferation, leaving 
a small number of partially dysfunctional antigen-specific T cells [Zhang, 2013]. Deletional T cell 
tolerance in AML-bearing hosts appears to be regulated by host APCs especially CD8  DCs as it 
can be reversed in vivo following the administration of agonistic anti-CD40 antibody (Ab), which 
results in enhanced anti-leukemia T cell immunity and prolonged survival [Kline, 2013]. This body 
of data suggest that activation of innate immunity by enhancing phagocytosis of AML cells and 
inducing antigen presentation to CD8 T cells could overcome tolerance and promote clinically 
meaningful immunity against AML. 
Chemotherapeutic agents such as azacitidine, venetoclax, and anthracyclines, used in the treatment 
of AML and MDS, are known to induce endoplasmic reticulum stress and promote translocation 
of the chaperone protein, calreticulin, to the surface of cancer cells. Calreticulin stimulates 
phagocytosis by macrophages and DCs via their expression of CD91 (low-density lipoprotein- 
receptor related protein). Calreticulin expression has also been observed on viable malignant cells–
including leukemia blasts. Induction of calreticulin alone is not sufficient for stimulating 
macrophage phagocytosis. Calreticulin-mediated phagocytosis of cancer cells can be inhibited by 
increased expression of CD47, a mechanism co-opted by leukemic cells to promote survival 
through evasion of phagocytosis [Chao, 2010]. Additionally, it has been shown that AML cells 
engineered to express high-levels of calreticulin promoted enhanced anti-leukemia T cell 
responses and prolonged survival in mice, an effect that did not occur in Rag2-/- mice, or following 
in vivo T cell depletion [Chen, 2017]. This demonstrates the dependence on adaptive immunity. 
CD47 over-expression on leukemia cells is targetable through receptor blockade. Limited clinical 
response was reported in patients with AML receiving magrolimab (Hu5F9-G4), a CD47 targeting 
antibody as monotherapy [Vyas, 2018; Sallman, 2019b]. In contrast, promising clinical activity 
has recently been reported in patients with MDS and AML receiving magrolimab in combination
with azacitidine. Objective responses were reported in 91% (in 31/33 patients: 42% (complete 
remission [CR], 24% marrow CR, 3% partial remission [PR], 21% hematologic improvement (HI)
alone, 9% stable disease [SD]) of untreated patients with MDS [Sallman, 2019b]. Similarly, in 
treatment-naïve AML patients unfit for intensive chemotherapy, objective responses were reported 
in 63% (27/43) of the patients, including 42% CR, 12% marrow CR, 2% PR, and 7% morphologic 
leukemia-free state (MLFS) [Sallman, 2020a]. Common treatment-related adverse events (AEs)
included anemia (38%), fatigue (21%), neutropenia (19%), thrombocytopenia (18%) and infusion 
reactions (16%). In transfusion-dependent patients, 58% of MDS and 64% of AML patients
became transfusion-independent. 
Dysregulation of the apoptotic pathway has been well described in AML, including overexpression 
of BCL-2, which is an important anti-apoptotic protein. This has supported the development of 
BCL-2 inhibitors to promote the induction of apoptosis in AML cells, as evidenced in a Phase 3 
study of venetoclax administered with azacitidine in treatment-naïve AML patients [DiNardo, 
2020b]. Composite CR was achieved in 66.4% of treatment-naïve AML patients receiving 
venetoclax and azacitidine compared to 28.3% of those receiving azacitidine monotherapy. An 
improvement in median OS was also reported (14.7 months for the venetoclax-azacitidine group 
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BCL-2 inhibitor that has been Food and Drug Administration (FDA) approved in combination 
with azacitidine for the treatment of newly diagnosed AML. 
1.5
SL-172154 
1.5.1
Mechanism of Action 
The non-
cancer immunotherapy suggests that the two pathways could be complimentary or synergistic in 
combination and have the potential to improve survival in patients with MDS and AML. In an 
attempt to improve upon current paradigms, Shattuck Labs has developed a bifunctional fusion 
protein platform, capable of simultaneously blocking ‘checkpoints’ while activating tumor 
necrosis factor (TNF) receptor superfamily co-stimulators. Shattuck’s Agonist Redirected 
Checkpoint (ARC) platform adjoins the extracellular domain (ECD) of a select type 1 membrane 
protein to the ECD of a select type 2 membrane protein, via a central Fc domain. Using this 
approach, combination immunotherapy can be achieved by a single fusion protein. Superior 
preclinical activity has been observed compared to the separate administration of two individual 
antibodies against identical targets [de Silva, 2019]. As a result, Shattuck sought to develop a 
SIRP -Fc-CD40L ARC™ fusion protein, SL-172154, as a means to target these pathways with a 
single compound. Tumor-expressed CD47 can provide a “do not eat me” signal to APCs, including 
macrophages and DCs, through the binding of SIRP  [Figure 1A]. SIRP -Fc-CD40L (SL-172154) 
can relieve this inhibitory signal through blockade of CD47 with the SIRP
domain of the ARC, 
while simultaneously providing an “eat me” signal via co-stimulation of CD40 by CD40L
[Figure 1B]. This enhances tumor phagocytosis, APC activation, increased antigen 
processing/presentation, and induction of an antitumor antigen-specific CD8+ T cell response. 
Combination treatment of SIRP -Fc-CD40L with checkpoint blocking agents increases CD40 
target density which may stimulate a more potent and durable anti-tumor response. 
Figure 1 
SIRP -Fc-CD40L (SL-172154) Mechanism of Action 
(A) 
, macrophages and DCs). 

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(B) 
-Fc-CD40L directly induces APC activation through CD40 stimulating an antigen-specific CD8 T cell response. 
Combinations with checkpoint blocking agents increase target density for the ARC and may stimulate a more potent and 
durable anti-tumor response. 
1.5.2
Summary of Nonclinical Data 
A brief summary of the nonclinical data is provided in the following section. SIRP -Fc-CD40L 
has demonstrated functional activity both in vitro and in vivo [de Silva, 2019]. Detailed 
information is presented in the SL-172154 Investigator’s Brochure (IB).  
1.5.2.1 
Pharmacology Studies 
1.5.2.1.1
In Vitro Pharmacology 
In vitro, SL-172154 was shown to bind to its cognate targets, CD47 and CD40, both individually 
and simultaneously. High binding affinity for CD47 and CD40 was noted as well as a slow off rate 
(KD values of 0.628 nM and 4.74 nM, respectively), indicating a longer on target resident time. 
This longer resident time could be of benefit in the tumor microenvironment where CD47 is known 
to be expressed. CD40-mediated activity by SL-172154 was demonstrated in a NF B reporter 
system in which CD40-dependent signaling was stimulated in the absence of Fc receptor cross-
linking, and in cultured human peripheral blood mononuclear cells (PBMCs) in which dose-
dependent proliferation, an increase in the number of interleukin (IL)-2 secreting PBMCs, and the 
secretion of multiple cytokines were observed. 
Tumor-macrophage engulfment assays were performed to determine if SL-172154 similarly 
potentiates phagocytosis of tumor cells by macrophages in combination with antibody-dependent 
cell-mediated cytotoxicity (ADCC)-competent antibodies including rituximab, cetuximab, 
trastuzumab, an anti-CD38 antibody, an anti-SLAM-F7 antibody, and an anti-BCMA antibody. 
Generally, across the antibodies and tumor cell lines, macrophage-mediated phagocytosis was 
enhanced with the SL-172154/antibody combination in comparison to SL-172154 alone or 
antibody alone.  
In other tumor-macrophage engulfment assays, both calreticulin and Fc receptor engagement was 
demonstrated to be required for efficient phagocytosis of CD20+ B-cell lymphoma cells by the 
combination of SL-172154 and rituximab. Addition of a calreticulin-blocking peptide and 
blocking Fc-
combination with SL-172154.  
The combination of SL-172154 with the hypomethylating agent, azacitidine, enhanced 
phagocytosis of AML and chronic myeloid leukemia (CML) tumor cell lines (Kasumi-3 and K562, 
respectively). A similar effect was observed with the combination of SL-172154 with the BCL-2-
inhibitor, venetoclax. Upregulation of CD47, the target for SIRP  and induction of the 
prophagocytic protein, calreticulin, was observed with azacitidine. 
1.5.2.1.2 
In Vivo Pharmacology 
It has been previously reported that CD47 blockade in vivo leads to rapid upregulation of CD86 
and MHC-II on splenic CD8 + DCs [Yi, 2015]. In mice given a single intravenous (IV) injection 
of the murine surrogate of SL-172154 (
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proliferation of both CD4+ and CD8+ splenic DCs was observed, which matched the duration of 
activation observed with murine CD40 antibodies [de Silva, 2019]. Furthermore, CD40 
stimulation had a more prolonged effect on the same DC populations.  
In the murine CT26 colorectal tumor xenograft 
-Fc CD40L given via
intraperitoneal administration enhanced tumor control and rejection of both primary and 
rechallenge tumors, suggesting that a more robust memory response was generated, in comparison 
to murine anti CD47, murine anti CD40, or combination antibody therapy. Additionally, in two 
mouse CD20+ hematological tumor models (WEHI3 and A20), intraperitoneal administration of 
-Fc-CD40L in combination with murine anti-CD20 led to decreased tumor volumes in 
-Fc-CD40L or anti-CD20 monotherapy. This effect 
on tumor growth inhibition could be abrogated by blocking the type I interferon response.
1.5.2.2
Toxicology Studies in Non-Human Primates
In two repeat dose toxicology studies, cynomolgus monkeys received SL-172154 at 0 (vehicle), 
0.1, 1, 10, or 40 mg/kg by intravenous infusion (30 or 60 minutes) once weekly for up to 5 weeks. 
Dose-dependent receptor occupancy was observed with up to >90% CD40 receptor occupancy on 
PBMCs and up to ~80% CD47 receptor occupancy on erythrocytes. Following intravenous 
administration of SL-172154, transient and reversible decreases in platelets (minimal to moderate) 
and lymphocytes (mild) were observed. Additionally, the increased splenic weight and lymphoid 
cellularity observed in the Good Laboratory Practice (GLP) study are consistent with a 
pharmacological effect; these findings were reversed following the 4-week off-dose period. 
While SL-172154 was shown to bind to CD47 receptors on monkey erythrocytes in vivo, clinical 
hematology (erythrocyte count, hemoglobin, and hematocrit) and serum chemistry (lactate 
dehydrogenase and total bilirubin) evaluations at multiple timepoints in the study showed no 
evidence of hemolysis or anemia. Additionally, the in vitro incubation of SL-172154 with human 
whole blood did not result in any detectable hemolysis. SL-172154’s lack of hemolysis of 
erythrocytes is likely because it does not engage effector Fc gamma receptors unlike CD47 
targeting antibodies such as magrolimab [Sikic, 2019].
The principal SL-172154-related toxicity finding in the GLP toxicology study was the occurrence 
of dose-dependent infusion-related reactions at 10 mg/kg (2 of 6 animals) and 40 mg/kg (6 of 10 
animals) during the third or fourth doses of SL-172154. These infusion-related reactions (IRRs) 
were coincident with the emergence of anti-drug antibody (ADA) and complement activation. 
ADA was present in all SL-172154-treated monkeys by Day 15 (Dose 3) and complement 
activation is commonly associated with the presence of ADA. Emergence of ADA in the non-
human primate studies was expected given that SL-172154 is based on human amino acid 
sequences which have 82% identity to the corresponding cynomolgus sequences.  
In the GLP toxicity study in cynomolgus monkeys, there were no findings in the safety 
pharmacology endpoints assessing the central and peripheral nervous systems, respiratory system, 
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1.5.2.3 
Toxicokinetic Studies
In two studies in cynomolgus monkeys, systemic exposure, as evaluated by maximum observed 
concentration (Cmax) and area under the serum concentration-time curve (AUC), increased in a 
greater than dose-proportional manner on Day 1. Clearance of SL-172154 from serum decreased 
as the dose increased, suggesting a saturable clearance mechanism. In the GLP Study, the mean 
terminal elimination half-life (t½) on Day 1 was approximately 0.4 hour following a 1.0 mg/kg 
dose, and approximately 1 hour after the 10 and 40 mg/kg doses. Potential explanations for rapid 
drug clearance include an antigen sink due to the ubiquitous expression of CD47 on peripheral 
blood cells (i.e., RBC, platelets, and PBMCs), target-mediated uptake at early time points with 
trafficking of cells (e.g., PBMCs), and binding of drug to peripheral tissues. In both studies, 
compared to Day 1, systemic exposure to SL-172154 following multiple once-weekly intravenous 
infusions was reduced on Day 29, with the decrease appearing more marked in the GLP toxicity 
study compared to the dose-range finding study. As all monkeys were positive for ADA by Day 15 
(Dose 3) in both studies, the production of ADA to SL-172154 was likely the primary factor 
contributing to the lower serum SL-172154 concentrations observed on Day 29 compared to 
Day 1.
For further information, please refer to the SL-172154 IB.
1.6
Summary of Clinical Data
A brief summary of the clinical data is provided for SL-172154. Detailed information is presented 
in the current SL-172154 IB. As of 25 May 2023, SL-172154 has been administered IV to 79
subjects and intratumorally to 5 subjects with cancer. 
Study SL03-OHD-101 is a Phase 1, first-in-human, open-label, multicenter, dose escalation study 
to investigate the safety, pharmacokinetic (PK), pharmacodynamic (PD), and clinical activity of 
SL-172154 administered to subjects with platinum-ineligible ovarian, fallopian tube, or primary 
peritoneal cancers. SL-172154 was administered on two schedules. In dosing Schedule 1, 
SL-172154 was administered on Days 1, 8 and 15 of a 28-day cycle and then every 2 weeks 
(Days 1 and 15) in 28-day cycles starting at Cycle 2. In dosing Schedule 2, SL-172154 was
administered weekly (i.e., Days 1, 8, 15 and 22 in 28-day cycles). Twenty-seven subjects were 
enrolled into 7 dose cohorts where SL-172154 was administered as a 30, 60 or 120-minute infusion 
in ascending doses of 0.1 mg/kg (n=3, Schedule 1), 0.3 mg/kg (n=3, Schedule 1), 0.3 mg/kg (n=3, 
Schedule 2), 1.0 mg/kg (n=4, Schedule 2), 3.0 mg/kg (n=6, Schedule 2), 3.0 mg/kg (n=3, 
Schedule 1), and 10.0 mg/kg (n=5, Schedule 2). Subjects treated with IV SL-172154 at 3.0 mg/kg 
in Study SL03-OHD-101 cleared the 28-day dose-limiting toxicity (DLT) evaluation period with 
no DLTs. The maximum administered dose (MAD) level of SL-172154 evaluated in Study 
SL03-OHD-101 was 10.0 mg/kg given once weekly. One DLT (Grade 3 ALT increased) was 
reported in the 10.0 mg/kg cohort. A maximum tolerated dose (MTD) was not reached. 
All subjects (100%) reported AEs with the most frequently (>20% of subjects) reported AEs being 
IRR (18 subjects, 67%), fatigue (12 subjects, 44%), nausea (9 subjects, 33%), constipation 
(6 subjects, 22%), and diarrhea (6 subjects, 22%). AEs considered related to SL-172154 per 
Investigator assessment were reported in 24 subjects (89%), with the most common (>15% of 
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The most common Grade 3 or 4 TEAE (>5%) were AST increased, embolism, hypertension, IRR, 
lymphopenia and sepsis. Drug-related Grade 3 or 4 TEAEs were AST increased (n=2), 
lymphopenia (n=2), neutropenia, thrombocytopenia, back pain, muscular weakness, anemia, ALT 
increased and IRR each in one subject. Treatment-related Grade 3 ALT/AST elevations were 
reported in one subject treated at 10.0 mg/kg. The ALT/AST elevations normalized with 
withholding of treatment. 
Six subjects (22%) reported serious TEAEs (embolism n=2, sepsis n=2, large intestine infection 
n=1, lower gastrointestinal hemorrhage n=1, small intestinal obstruction n=1); all were Grade 3, 
and none were considered drug-related.
No Grade 5 AEs have been reported and no AEs led to permanent discontinuation of SL-172154. 
PK data for 27 subjects in Study SL03-OHD-101 (overall intravenous dose range, 0.1 to 10.0 
mg/kg) were estimated using noncompartmental analysis. Following a single and multiple IV 
infusions of 0.1 to 10 mg/kg SL-172154, mean serum SL-172154 Cmax was reached at the end 
of infusion and ranged from 118 ng/mL to 115536 ng/mL. Serum SL-172154 concentrations 
showed multi-phasic decline and were quickly cleared with a half-life generally below 1.3 hour 
for all dose levels. In general, the increase in serum SL-172154 Cmax and AUClast values with 
dose was greater than dose-proportional, a finding that is consistent with target-mediated drug 
disposition. There was a >500-fold increase for Cmax and AUC for a 100-fold increase in dose 
across the entire dose range (0.1 to 10 mg/kg). No accumulation of SL-172154 after multiple 
doses was observed (accumulation ratio, <1.56). 
In the current study, as of May 25, 2023, 37 subjects with higher-risk MDS or AML received 
SL-172154 either as monotherapy (19 subjects; doses of 1, 3, or 6 mg/kg) or in combination with 
AZA (18 subjects; doses of 1, 3, or 6 mg/kg). Sixteen subjects (84.2%) in the monotherapy 
cohorts and 12 subjects (66.7%) in the SL-172154 + AZA cohorts had at least one SL-172154-
related TEAE. Thirteen subjects (68.4%) in monotherapy cohorts and 8 subjects (44.4%) in SL-
172154 + AZA cohorts experienced an IRR. One subject that received 6.0 mg/kg SL-172154 + 
AZA experienced a DLT of Gr 3 IRR. Based on the SMC’s recommendation further enrollment 
into 6 mg/kg + AZA was stopped. SMC reviewed all the available safety data and selected 3
mg/kg SL-172154 as the dose for expansion cohorts. Enrollment is currently ongoing in the dose 
expansion cohorts.
SL-172154 is also being investigated in combination with either pegylated liposomal doxorubicin 
or mirvetuximab soravtansine in an ongoing Phase 1b Study in ovarian cancer. As of 25 May 2023, 
15 subjects have been enrolled onto this study. 
In summary, SL-172154 has demonstrated an AE profile that has been manageable and acceptable 
in the context of benefit-risk. No clinically significant findings were identified.  
Hematologic toxicities have been reported with Fc-
-Fc fusion 
proteins, while hepatotoxicity and cytokine release syndrome (CRS) have been reported with 
CD40 agonist antibodies. Transient decreases in hemoglobin (without evidence of hemolysis), 
platelets and lymphocytes has been observed following infusion of SL-172154. Overall, the 

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benefit-risk profile of SL-172154 supports the continued investigation of SL-172154 in subjects 
with advanced cancer. 
1.7
Study Rationale 
SL-172154 is a novel Fc-fusion protein consisting of human SIRP and CD40L 
(SIRP -Fc-CD40L). SL-172154 not only inhibits CD47/SIRP
axis but it also augments cross 
presentation of antigens by APC to T cells through the costimulatory role of CD40L, thus bridging 
innate and adaptive immunity. SL-172154 potentiates macrophage phagocytosis when combined 
with agents that induce immunogenic tumor cell death (see SL-172154 IB). In clinical trials, 
CD47-targeted agents have limited monotherapy activity, whereas combination with agents such 
as azacitidine or venetoclax that induce prophagocytic signals (e.g., calreticulin) in leukemic blasts 
have resulted in improved response rates [Vyas, 2018; Sallman, 2019a]. 
SL03-OHD-104 is designed as a Phase 1a/1b open-label trial to evaluate the safety, PK, PD, and 
preliminary efficacy of SL-172154 monotherapy as well as in combination with azacitidine or in 
combination with azacitidine and venetoclax. Azacitidine and venetoclax are commonly used in 
clinical practice in these patient populations, with well-described safety and PK profiles for the 
individual agents and the combination. This is the first clinical trial to investigate the combination 
of these agents with SL-172154. Each component is anticipated to have activity on distinct targets, 
and these agents combined with SL-172154 have the potential to further bridge innate and adaptive 
immunity, thus potentially improving treatment outcomes without increasing toxicity. No 
overlapping toxicities, other than fatigue, are anticipated with SL-172154. Hematologic toxicities 
(e.g., hemolysis, interference with crossmatch) have not been observed with SL-172154 in ongoing 
clinical trials. 
Study SL03-OHD-104 will initially enroll approximately 5 subjects with relapsed or refractory 
disease (MDS or AML) to SL-172154 monotherapy dose escalation cohort at the starting dose of 
1.0 mg/kg SL-172154. Subjects will be enrolled into sequential dose levels of SL-172154 and 
assessed for DLT during the first 28 days. This will inform the safety, tolerability, PK, PD, and 
preliminary anti-tumor activity profile of SL-172154 monotherapy by dose level. 
While clinical response is possible with SL-172154 monotherapy, limited clinical responses have 
been observed with other investigational agents targeting CD47 and CD40 administered as 
monotherapy [Vonderheide, 2007; Vyas, 2018; Sallman, 2019a; Sikic, 2019]. The mechanism of 
action of SL-172154 suggests that combination therapy is likely to provide greater benefit. In 
addition, subjects with higher-risk MDS or AML often have rapidly progressing disease.  
When the SL-172154 monotherapy cohort completes the DLT evaluation period in Dose Level 2 
(3.0 mg/kg), enrollment may begin in parallel to the dose escalation cohorts investigating 
SL-172154 (starting dose 1.0 mg/kg) administered with azacitidine to maximize the potential for 
clinical benefit to participating subjects. Once the selected dose of SL-172154 administered with 
azacitidine is identified in dose escalation, enrollment of treatment-naïve subjects with AML to a 
safety run-in cohort (n=8) of SL-172154 administered with azacitidine and venetoclax will 
commence using the same SL-172154 dose.  

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The 3 mg/kg dose of SL-172154 was selected for the SL-172154 and azacitidine combination 
regimen and dose expansion cohorts are enrolling additional subjects to further evaluate the safety 
and efficacy of the combination regimen. In the dose expansion part of the study, approximately 
20 treatment naïve subjects with higher-risk MDS will be enrolled to receive SL-172154 at the 
selected dose with azacitidine (Part A). In addition, approximately 20 treatment naïve AML 
subjects with at least one known TP53 gene mutation or deletion will be enrolled to receive SL-
172154 at the selected dose with azacitidine (Part C). Once the SL-172154 dose in combination 
with azacitidine and venetoclax is confirmed during the safety run-in, approximately 20 treatment 
naïve subjects with AML (including safety run-in cohort and dose expansion) will be enrolled to 
receive SL-172154 with azacitidine and venetoclax (Part B).
Safety and efficacy will be further explored in Part D (with randomized control arm of 
azacitidine monotherapy). Approximately 60 treatment naïve subjects with higher-risk MDS will 
be randomized to three arms (approximately 20 subjects per arm). The three arms consist of two 
experimental arms at two dose levels of SL-172154 (1.0 mg/kg and 3.0 mg/kg) in combination 
with azacitidine, and one control arm for azacitidine monotherapy. The three arms will be 
stratified based on TP53 mutation status (TP53m vs TP53wt) and bone marrow blasts at baseline 
(<5% vs 
This will further evaluate the safety, and efficacy of different doses of SL-
172154, and help determine the contribution of SL-172154 to the anti-leukemic activity in the 
azacitidine plus SL-172154 treatment.  
SL-172154 will be administered on a weekly schedule for the first two cycles of treatment and 
biweekly during the third cycle and beyond. Although the optimal SL-172154 dosing schedule has 
not been established, less frequent dosing in later cycles is a reasonable approach to avoid frequent 
CD40 stimulation that may lead to chronic activation of APC and exhaustion of T cells [Rüter, 
2010]. It is anticipated that the disease burden would be substantially reduced during the first two 
cycles (first 2 months of therapy) of treatment when SL-172154 is combined with azacitidine or 
azacitidine and venetoclax [DiNardo, 2020a]. Thus, when SL-172154 is combined with either 
regimen, biweekly dosing beyond this time frame could facilitate a continued anti-tumor immune 
response. 
1.8
Potential Risks and Benefits 
1.8.1
Potential Risks
Potential risks to participants in the study are addressed by vigilant monitoring and safety 
guidelines as outlined below. The risks (evaluation of safety and tolerability) and potential benefits 
(evaluation of anti-tumor activity) of SL-172154 administered intravenously as a monotherapy 
was assessed in the Phase 1 first-in-human clinical trial, SL03-OHD-101, in subjects with relapsed, 
refractory ovarian cancer. Although the risks and potential benefits of SL-172154 have not been 
previously assessed in AML or MDS in other studies, the safety results from SL03-OHD-101 
provide relevant safety information for this study. Therefore, the assessment of potential safety 
concerns is based on (1) the published safety profiles of other CD40 agonists and CD47-
targeting agents; (2) non-human primate (NHP) toxicology data; and (3) safety data from the 
SL03-OHD-101 study. 

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Adverse events reported with other CD47-SIRP
targeting agents and CD40 agonists:
Anti-CD47 monoclonal antibodies (mAbs) 
-Fc fusion proteins have been evaluated in 
patients with hematologic malignancies and solid tumors. Adverse events that have been observed 
include anemia, hemagglutination, hyperbilirubinemia, lymphopenia, thrombocytopenia, 
neutropenia, elevation of hepatic transaminases, fatigue, headache, fever, and IRRs [Chao, 2019; 
Sikic, 2019; Eladl, 2020]. A common AE reported with CD40 agonist mAbs was transient 
infusion-related CRS characterized by fevers, rigors, chills, and other symptoms such as headache 
and back pain. Other AEs include fatigue, rash, elevation of hepatic transaminases, lymphopenia, 
anemia, thrombocytopenia, neutropenia, thromboembolism, and inflammatory eye disorders 
(conjunctivitis and ocular hyperemia). Immune-mediated events, including dermatitis, colitis, 
hypophysitis and thyroiditis, have not been seen with CD40 antibodies but remain a potential 
concern [Vonderheide, 2001; Vonderheide, 2007; Vonderheide, 2013a; Vonderheide, 2013b; 
Nowak, 2015; Sanborn, 2019].
Toxicities observed with SL-172154 in nonclinical toxicology studies in NHP: The underlying 
etiology of the SL-172154-related effects in NHP is most likely due to a combination of both the 
pharmacologic activity of the molecule and to immunologic reactions to SL-172154 
administration. The following are potential contributory factors to the dose-dependent IRRs 
observed in NHP during or following the third to the fifth dose of SL-172154: (1) development of 
ADA and downstream complement activation; (2) elevations in serum cytokines; and (3) post-dose 
changes in peripheral blood lymphocyte counts. The emergence of ADA in the non-human primate 
studies was expected given that SL-172154 is based on human amino acid sequences which have 
82% identity to the corresponding cynomolgus sequences. SL-172154 has >99% identity to the 
corresponding human proteins and hence SL-172154 is considered to have a low risk of 
immunogenicity in humans. 
Safety profile of SL-172154 in the context of azacitidine and venetoclax: The combination of 
SL-172154 and azacitidine or SL-172154 with azacitidine and venetoclax has not previously been 
studied in humans. The AE profile reported for azacitidine or azacitidine and venetoclax in patients 
with AML has been reported in a Phase 3 study [DiNardo, 2020b]. Hematologic AEs reported in 
 20% of patients with AML receiving azacitidine or azacitidine with venetoclax included 
thrombocytopenia, 
neutropenia, 
febrile 
neutropenia, 
anemia, 
and 
leukopenia 
while 
non- 
of patients included infections, nausea, 
constipation, diarrhea, vomiting, hypokalemia, pyrexia. The incidence of neutropenia and febrile 
neutropenia was higher with the combination of azacitidine and venetoclax in comparison to 
azacitidine alone. In addition, fatigue, peripheral edema, and dec
patients treated with azacitidine and venetoclax while these same AEs were reported in <20% of 
patients in the azacitidine alone arm. Fatigue has been reported following administration with 
CD47-
mAbs. In addition, fatigue is a 
frequently reported treatment-related AE (Investigator attribution) associated with intravenous 
SL-172154 monotherapy in the SL03-OHD-101 study (Section 1.6). Anemia without evidence of 
hemolysis, and transient decreases in lymphocyte and platelet counts have been observed with SL-
172154. These hematologic effects are not a consequence of myelosuppression. The expression of 
CD40 on platelets and B cells may explain the hematologic effects observed with CD40 agonists. 

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Inwald et al. showed that the binding of sCD40L to CD40 induces P-selectin expression and 
IIb 3 without inducing platelet aggregation [Inwald, 2003]. We and others have 
shown that ligation of CD40 receptor on B cells by CD40 agonists lead to transient egress of B 
cells from the circulation [Vonderheide, 2007; Lakhani, 2021]. It is not expected that SL-172154 
would exacerbate the myelosuppression commonly observed with azacitidine alone or in 
combination with venetoclax.  
Potential risks of SL-172154 administration in SL03-OHD-104 study: 
The potential risks noted below are based on observations in the SL-172154 NHP studies, the 
Phase 1 clinical studies, or select toxicities reported with other CD47 or CD40-targeted agents. 
1) IRRs and CRS: In Study SL03-OHD-101, 45 treatment-related events of IRR were reported in 
18 subjects. Thirteen subjects (48.1%) had IRRs that led to infusion interruption. IRRs did not 
lead to study drug withdrawal in any subject. The median number of IRR events in subjects 
experiencing an IRR was 2, with a range of 1 to 9. All SL-172154-related IRRs were Grade 1 
or 2, except for 1 subject dosed with 3.0 mg/kg on Schedule 1 who had a Grade 3 event. No 
IRR was deemed to be serious. All IRRs resolved with no sequelae. Collectively, the frequency 
of subjects experiencing IRR events and the frequency of IRR events increased with increasing 
dose. Symptomatic manifestations of the IRR events variably include fever, chills, rigors, back 
pain and rash. Most of the IRRs were reported to be relatively short in duration and occurred
near the end of the infusion or immediately post-infusion. All of the IRR events were readily 
managed with temporary interruption of the infusion and/or treatment medications; several 
subjects received premedications (such as diphenhydramine, famotidine, and acetaminophen) 
prior to their next dose. In the current Study, Thirteen of the 19 subjects (68.4%) who received 
monotherapy had 32 IRR events. The median number of IRR events was 3 with a range of 1 
to 5. All IRR events were Grade 1 or 2, except for 1 subject each dosed with 3 mg/kg and 6 
mg/kg who had Grade 3 events.  All IRR events resolved with no sequelae. Most IRR events 
(68.8%) started during the SL-172154 infusion or less than 2 hours post-end-of-infusion 
(25.0%). Eight of the 18 subjects (44%) who received SL-172154 + AZA had 19 IRR events. 
The median number of IRR events was 1 with a range of 1 to 8. All IRR events were Grade 1 
or 2, except for 1 subject dosed with 6 mg/kg who had Grade 3 events. One Grade 3 IRR (6 
mg/kg SL-172154 + AZA) was deemed serious. All IRR events resolved with no sequelae. All 
IRR events started during the SL-172154 infusion. 
2) No CRS has been observed in the SL03-OHD-101 study and one Gr 1 CRS has been reported 
in the current Study in a subject with AML in the setting of sepsis. The steps taken to minimize 
the risks associated with IRRs and CRS include administration in an outpatient oncology clinic 
or inpatient setting by experienced health care providers, mandatory premedication prior to 
SL-172154 administration for IRR prophylaxis, management guidelines (e.g., SL-172154 
infusion adjustments/interruptions, rescue treatments), and extended monitoring when 
indicated. Recommendations to identify and manage infusion-related IRRs and CRS are
outlined in the Toxicity Management Guidelines section of the protocol (Section 3.8). 
3) Immunogenicity: SL-172154 has >99% identity to the corresponding human proteins and 
hence SL-172154 is considered to have a low risk of immunogenicity in humans. Subjects in 
the clinical trial SL03-OHD-104 will be monitored starting at baseline and serially for ADA. 

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In the event of a positive ADA response, antibody titer will be measured, and antibody isotype 
will be characterized. A guideline for monitoring and management of IRR including 
hypersensitivity reactions (HSRs) is included in Section 3.8.1. 
4) Hematologic toxicity: Anemia and thrombocytopenia have been reported with CD47 targeted 
agents that have an active Fc-domain (e.g., magrolimab, TTI-621, TTI-622). Interference with 
crossmatch has been reported with some CD47 targeted agents (e.g., magrolimab, ALX-148). 
Treatment-related Grade 3 or 4 anemia (n=1), thrombocytopenia (n=1), neutropenia (n=1) and 
lymphopenia (n=2) were reported in SL03-OHD-101. In study SL03-OHD-104, complete 
blood counts will be assessed frequently on treatment to monitor for hematologic toxicity. 
Supportive therapy (growth factors, prophylactic antibiotics, and active treatment for 
infections) will be provided according to standard medical practice; dose modification for 
hematologic toxicity will follow recommendations provided in the protocol and product 
information for approved agents. To date, hemolysis has not been observed in SL03-OHD-
101; the absence of hemolysis is likely due to the inactive Fc domain of SL-172154 [Chow, 
2019]. To investigate the possible risk of interference with pre-transfusion testing due to SL-
172154, blood phenotyping, type and screen (ABO/Rh), and direct antiglobulin test (DAT) 
was performed before and following exposure to SL-172154 in SL03-OHD-101. No 
interference with crossmatch resolution has been observed in subjects treated to date in SL03-
OHD-101.  
5) Immune-Related Adverse Events (irAEs): As experience with CD47 and CD40 targeted agents 
has expanded, it has become apparent that the typical irAEs described with CTLA-4 and PD-
1 inhibitors are not being observed with these agents. irAEs have not been reported in the 
current safety profile of SL-172154. Nevertheless, it is unknown if irAEs resulting from a 
breakdown of self-tolerance could occur with SL-172154 administration alone or in 
combination with azacitidine or venetoclax.  
In summary, this Phase 1 study has taken the following precautions to minimize potential risks: 
(1) the study is being conducted at centers that have extensive experience with this class of 
agents and the management of associated toxicities; (2) the starting dose of SL-172154 is a 
dose that has been administered to patients with cancer; (3) patients treated at each SL-172154 
dose level would be followed for the duration of the DLT assessment period before escalating 
to the next higher dose level of SL-172154; (4) administration of SL-172154 in an oncology 
treatment center/hospital allows for close monitoring of subjects for AEs and for timely action; 
(5) guidelines for management of AEs based on established guidelines [Lee, 2014; Haanen, 
2017; Puzanov, 2017; Rosello, 2017; Brahmer, 2018; Porter, 2018] are provided in the 
protocol; and (6) a Safety Monitoring Committee (SMC) will meet at least monthly during 
dose escalation and every 2 months during dose expansion to review emerging toxicities and 
assess the impact of these toxicities on study conduct.  
1.8.2
Potential Benefits
The clinical benefits of SL-172154 in subjects with MDS and AML are unknown as no other 
clinical trials have been conducted to date. SL-172154 targets both the CD40/CD40L and the 
inhibitors in combination with CD40 agonists. High expression of CD47 is reported across 

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aspirate prior to, on-treatment and 
following treatment with SL-172154 
administered alone or with azacitidine 
OR azacitidine + venetoclax in subjects 
with higher-risk MDS or AML
Changes in T cells subsets, B cells, 
macrophages and DCs
 Evidence of SL-172154 localization (CD47 or 
CD40 receptor occupancy) on hematopoietic 
cells and/or leukemic cells in the bone marrow 
and peripheral blood
3.
DESCRIPTION OF STUDY DESIGN 
SL03-OHD-104 is an open label, multicenter, Phase 1a/1b trial in subjects with higher-risk (i.e., 
intermediate, high or very high risk by IPSS-R) MDS or AML as depicted in the Study Schema.
The study is designed to evaluate the safety, PK, PD effects, and preliminary anti-tumor activity 
of SL-172154 monotherapy and SL-172154 administered with either azacitidine or azacitidine and 
venetoclax. Throughout the treatment period (monotherapy as well as combination regimens) for 
all subjects, an ongoing review of available safety data will be undertaken by a SMC as described 
in Section 7.8. Subjects will receive SL-172154 as monotherapy or administered with azacitidine 
with or without venetoclax until documented disease progression, unacceptable toxicity or 
intolerance, withdrawal of consent, or the subject meets other criteria for discontinuation
(whichever occurs first) as defined in Section 3.14. 
The starting intravenous infusion dose of 1.0 mg/kg in Study SL03-OHD-104 is supported by 
safety data in the first-in-human, dose escalation Study SL03-OHD-101 in which SL-172154 was 
administered once weekly to 4 subjects at 1.0 mg/kg, 8 subjects at 3.0 mg/kg, and 5 subjects at 
10.0 mg/kg. One DLT was reported at the MAD of 10.0 mg/kg (Section 1.6). Further information 
on the safety profile of SL-172154 is provided in the SL-172154 IB. Based on safety data obtained 
to date, a SL-172154 dose of 1.0 mg/kg was chosen as the initial dose level for evaluation in 
subjects with higher-risk MDS or AML in Study SL03-OHD-104. 
In Study SL03-OHD-104, SL-172154 will be administered once weekly during Cycles 1 and 2 and 
biweekly during Cycle 3 and thereafter, in 28-day cycles; the first 28-day cycle will be the DLT 
evaluation period for each subject (Section 3.6). For all subjects in all cohorts, prophylactic 
premedication for IRR with dexamethasone, an antipyretic and antihistamines should be 
administered at least 30 minutes prior to each SL-172154 administration. For the dose and 
schedule of prophylactic premedications, please see Sections 3.7.3 and 3.7.4. Treatment will be 
administered in 28-day cycles until at least one of the study treatment discontinuation criteria is 
met.
The study will initially enroll sequential cohorts of approximately 5 subjects with relapsed or 
refractory disease (AML or higher-risk MDS) to the SL-172154 monotherapy dose escalation 
cohort. The planned dose escalation and duration of infusion for SL-172154 are outlined in 
Table 1; the starting SL-172154 monotherapy dose is 1.0 mg/kg.  
When the SL-172154 monotherapy cohort completes the DLT evaluation period in Dose Level 2 
(3.0 mg/kg), enrollment into the SL-172154 dose escalation in combination with azacitidine cohort 
may initiate in parallel (SL-172154 starting dose, 1.0 mg/kg). Sequential cohorts of approximately 
5 subjects with relapsed/refractory AML or higher-risk MDS will be enrolled; the planned dose 
escalation and duration of infusion for SL-172154 are outlined in Table 2. Additionally, previously 

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untreated subjects with AML and known adverse cytogenetics (e.g., ELN adverse risk group) as 
well as previously untreated subjects with MDS with at least one TP53 gene mutation/deletion
may be considered for enrollment into this cohort. Azacitidine (IV or SQ) will be administered at 
the standard dose and schedule. Dose escalation of SL-172154 administered with azacitidine will 
continue until a safe dose of SL-172154 is identified for the combination. 
Once the selected dose of SL-172154 administered with azacitidine is identified in dose escalation, 
enrollment into a safety run-in cohort (n=8) of SL-172154 administered with azacitidine and 
venetoclax will commence using the same SL-172154 dose and duration of infusion. Treatment-
naïve subjects with AML will be enrolled.
The following cohorts will utilize the modified toxicity probability interval (mTPI-2) design [Guo, 
2017] with a target DLT rate of 20% for the MTD: 
SL-172154 monotherapy dose escalation
SL-172154 and azacitidine dose escalation cohort
SL-172154, azacitidine and venetoclax safety run-in cohort
The dose escalation decision rules based on mTPI-2 model are outlined in Section 9.1.1. In 
selecting the dose of SL-172154 for the combination regimen(s) to be evaluated in the dose 
expansion cohorts, the totality of the data from the dose escalation phase, including the safety of 
the combination and PD activity will be considered. 
Upon identification of a selected dose for the SL-172154 and azacitidine combination regimen, a 
dose expansion cohort will enroll additional subjects to further evaluate the safety and efficacy of 
the combination regimen. In the dose expansion part of the study, approximately 20 treatment 
naïve subjects with higher-risk MDS will be enrolled to receive SL-172154 at the selected dose 
with azacitidine (Part A) and will include subjects with wild-type TP53 and TP53 gene 
mutation/deletion. Clinical outcomes are shown to be distinct between these patient populations 
[Daver, 2022]. In addition, approximately 20 treatment naïve AML subjects with a known TP53 
gene mutation/deletion will be enrolled to receive SL-172154 at the selected dose with azacitidine 
(Part C).  
Once the SL-172154 dose in combination with azacitidine and venetoclax is confirmed during the 
safety run-in, approximately 12 additional treatment-naïve subjects with AML will be enrolled 
into dose expansion (Part B) to have approximately 20 subjects receive SL-172154 with azacitidine 
and venetoclax. 
3.1 
Dose Escalation Cohorts 
During dose escalation (monotherapy or combination regimen), the following guideline should be 
followed if an event of CRS occurs on Cycle 1 Day 8 or later: 
Grade 2 CRS: SL-172154 dose should not be escalated by more than 50% between subsequent 
dose levels 
Grade 3 CRS: SL-172154 dose should not be escalated by more than 25% between subsequent 
dose levels 

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3.1.1
SL-172154 Monotherapy Dose Escalation
Figure 2
SL-172154 Monotherapy 
Subjects with AML or higher-risk MDS being treated in the relapsed/refractory setting will be 
enrolled in this cohort. SL-172154 (Dose Level 1, 1.0 mg/kg) will be administered once weekly 
by IV infusion on Days 1, 8, 15, and 22 during Cycles 1 and 2, and biweekly on Days 1 and 15
during Cycle 3 and thereafter (Figure 2). One cycle consists of 28 days. Premedication as 
prophylaxis for IRR with an antipyretic and antihistamines should be administered at least 
30 minutes prior to each SL-172154 administration, as described in Section 3.7.3. Subjects will be
enrolled in cohorts of approximately 5 subjects into sequential dose levels of SL-172154 and
assessed for DLTs during the first cycle (28 days) of treatment. DLT criteria are defined in 
Section 3.6. The planned dose escalation and duration of infusion of SL-172154 is outlined in
Table 1. At each dose level, a minimum 3-day stagger between dosing the first and second subject 
is required. Treatment will be administered in 28-day cycles until at least one of the study treatment 
discontinuation criteria is met (Section 3.14). Subjects will be followed according to the Schedule 
of Assessments in Section 6.1.
When the SL-172154 monotherapy cohort completes the DLT evaluation period in Dose Level 2 
(3.0 mg/kg), the SL-172154 dose escalation in combination with azacitidine cohort (starting 
SL-172154 dose, 1.0 mg/kg) will open and enroll subjects in parallel as outlined in Section 3.2.1.
Table 1
SL-172154 Monotherapy Dosing
Dose Level (DL)
IV Dose of SL-172154a,b
Duration of Infusion
DL -1c
0.3 mg/kg
30 minutes (± 10 minutes)
DL 1 (starting dose)
1.0 mg/kg
60 minutes (± 10 minutes)
DL 2
3.0 mg/kg
180 minutes (± 15 minutes)
DL 3
6.0 mg/kg
180 minutes (± 15 minutes)
DL 4
10.0 mg/kg
180 minutes (± 15 minutes)
a.
SL-172154 will be administered once weekly on Days 1, 8, 15, and 22 during Cycles 1 and 2 and biweekly on Days 1 and 15 
during Cycle 3 and thereafter. One cycle consists of 28 days.
b.
subjects with body weight >100 kg, the dose to be administered should be the same as that calculated for a subject weighing 
100 kg.
c.
Dose level -1 at 0.3 mg/kg will be evaluated if 1.0 mg/kg is not safe per mTPI-2.

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3.2
SL-172154 Dose Escalation in Combination Treatment Arms
3.2.1
SL-172154 Administered with Azacitidine
Figure 3
SL-172154 in Combination with Azacitidine 
*5-2-2 schedule (i.e., azacitidine administration on Days 1-5 and 8-9) is allowed for azacitidine to avoid administration during 
weekends. 
The subjects with higher-risk MDS or AML enrolled in SL-172154 dose escalation in combination 
with azacitidine cohorts will have relapsed/refractory disease; previously untreated subjects with 
AML and known adverse cytogenetics (e.g., ELN adverse risk group) and previously untreated 
subjects with higher-risk MDS with a TP53 gene mutation/deletion may also be eligible for this 
cohort.
When the SL-172154 monotherapy cohort completes the DLT evaluation period in Dose Level 2 
(3.0 mg/kg), enrollment may begin in the dose escalation cohorts investigating SL-172154 
administered with azacitidine. In this cohort, SL-172154 (starting dose, 1.0 mg/kg) will be
administered by IV infusion once weekly on Days 2, 9, 16 and 23 during Cycles 1 and 2 and 
biweekly on Days 2 and 16 during Cycle 3 andthereafter (Figure 3). One cycle consists of 28 days. 
To escalate the dose of SL-172154 in combination with azacitidine, the corresponding 
monotherapy dose level for SL-172154 will have been cleared for safety. For example, the 
SL-172154 monotherapy 6.0 mg/kg cohort must be cleared before opening the SL-172154 at
6.0 mg/kg in combination with azacitidine cohort. The planned dose escalation and duration of 
infusion of SL-172154 is outlined in Table 2. At each dose level, a minimum 3-day stagger 
between dosing the first and second subject is required. Prophylactic premedication for IRR with 
dexamethasone, an antipyretic and antihistamines should be administered at least 30 minutes prior 
to each SL-172154 administration as described in Section 3.7.3. 
Subjects will be enrolled in cohorts of approximately 5 subjects into sequential dose levels of 
SL-172154 administered with azacitidine (75 mg/m2, IV or SQ on Days 1 to 7 or alternative 5-2-2
schedule) and evaluated for DLTs during the 28-day DLT evaluation period which starts from the 
first dose of azacitidine. DLT criteria are defined in Section 3.6. Treatment will be administered 
in 28-day cycles until at least one of the study treatment discontinuation criteria is met 
(Section 3.14). During therapy, management of azacitidine-related toxicity should follow the 
guidelines provided in the country’s current prescribing information (e.g., US Prescribing 
Information (USPI), Summary of Product Characteristics (SmPC), or Product Monograph).
Subjects will be followed according to the Schedule of Assessments in Section 6.2.

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SL-172154 will be administered once weekly by IV infusion on Days 2, 9, 16 and 23 during Cycle 
1 and 2 and biweekly on Days 2 and 16 during Cycle 3 and thereafter (Figure 4 and Table 3). One 
cycle consists of 28 days. Prophylactic premedication for IRR with dexamethasone and antipyretic 
and antihistamines should be administered at least 30 minutes prior to each SL-172154 
administration as described in Section 3.7.3. Azacitidine (75 mg/m2, IV or SQ on Days 1 to 7 or 
alternative 5-2-2 schedule) and venetoclax (target dose of 400 mg, oral, once daily) will be 
administered as described (Section 5.2 and Section 5.3) in 28-day cycles. A ramp-up schedule for 
venetoclax will be used with 100 mg (Day 1), 200 mg (Day 2), 400 mg (Day 3), and 400 mg once 
daily thereafter. A modified ramp-up schedule is required when a strong CYP3A inhibitor is co-
administered (Section 16.7).
Subjects will be enrolled in cohorts of approximately 5 subjects to receive the selected dose level 
of SL-172154 administered with azacitidine and venetoclax, and evaluated for DLT during the 
28-day DLT evaluation period which starts from the first dose of azacitidine and venetoclax; DLT 
criteria are defined in Section 3.6. Approximately eight subjects, in total, will be enrolled at a given 
dose in the safety run-in cohort evaluating SL-172154 administered with azacitidine and 
venetoclax prior to moving into the dose expansion cohort with this combination regimen. 
Treatment will continue until at least one of the study treatment discontinuation criteria is met 
(Section 3.14). During therapy, management of azacitidine-related or venetoclax-related toxicity 
should follow the guidelines provided in the country’s current prescribing information (e.g., USPI, 
SmPC, or Product Monograph). Subjects will be followed according to the Schedule of 
Assessments in Section 6.2. Since this cohort is receiving venetoclax, additional safety assessment 
is required to monitor for tumor lysis syndrome (TLS) (Section 3.7.5 and Section 6.2 Schedule of 
Assessments).
The safety as well as the available PK, PD and efficacy data from these subjects will inform the 
dose of SL-172154 selected to be further evaluated in dose expansion (Part B) when administered 
in combination with azacitidine and venetoclax to treatment-naïve subjects with AML.  
Table 3 
SL-172154 Administered with Azacitidine and Venetoclax
Dose Level (DL)
SL-172154a,b
Combination Regimen 2
DL -1bc
1 dose level lower that was 
evaluated in the SL-172154 + 
azacitidine dose escalation 
portion of the study
Azacitidine (75 mg/m2) SQ or IV on Days 1 to 7 
or 5-2-2 schedule in each 28-day cycle.
On days when both are administered, azacitidine 
administration should be completed at least 30 
minutes prior to the start of the SL-172154 
infusion.
Venetoclax (target dose 400 mg) PO QD in each 
28-day cycle.
DL 1b 
Dose selected in combination 
with azacitidine in dose 
escalation 
a. 
SL-172154 will be administered once weekly on Days 2, 9, 16 and 23 during Cycles 1 and 2and biweekly on Days 2 and 16 
during Cycle 3and thereafter. One cycle consists of 28 days. 
b. 
The actual body weight in kilograms (kg) will be used for dose calculation in all subjects whose 
subjects with body weight >100 kg, the dose to be administered should be the same as that calculated for a subject weighing 
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c. 
Dose level -1 at 0.3 mg/kg will be evaluated if 1.0 mg/kg is not safe per mTPI-2.  
3.3
Dose Expansion Cohorts  
3.3.1
Part A: SL-172154 Administered with Azacitidine in Subjects with Higher-Risk 
MDS
Treatment-naïve subjects with higher-risk (intermediate, high, or very high per IPSS-R) MDS will 
be enrolled to receive SL-172154 and azacitidine at a dose and schedule identified in the dose 
escalation part of the study to further evaluate the safety, PD effects, and efficacy of this regimen. 
Prophylactic premedication for IRR with dexamethasone, an antipyretic and antihistamines should 
be administered at least 30 minutes prior to each SL-172154 administration, as described in 
Section 3.7.3. The goal is to enroll approximately 20 subjects with MDS at the potential RP2D for 
this
combination regimen, including
subjects with wild-type TP53
and TP53 gene 
mutation/deletion. Treatment will be administered in 28-day cycles until at least one of the study 
treatment discontinuation criteria is met (Section 3.14). Enrollment of subjects in Part A of dose 
expansion may occur in parallel with enrollment of subjects in Part B (SL-172154 administered 
with azacitidine and venetoclax) and Part C (SL-172154 administered with azacitidine to AML 
subjects with TP53 mutation/deletion) of dose expansion.
3.3.2 Part B: SL-172154 Administered with Azacitidine and Venetoclax in Subjects with 
AML 
Once the SL-172154 dose in combination with azacitidine and venetoclax is confirmed during the 
safety run-in, approximately 12 additional subjects will be enrolled in the dose expansion cohort 
with this triplet combination regimen. Treatment-naïve subjects with AML will be enrolled to 
receive SL-172154, azacitidine, and venetoclax at a dose and schedule identified in the safety 
run-in part of the study to further evaluate the safety, PD effects, and efficacy of this regimen. 
Prophylactic premedication for IRR with dexamethasone, an antipyretic and antihistamines should 
be administered prior to each SL-172154 administration as described in Section 3.7.3. The goal is 
to enroll approximately 20 subjects with AML at the potential RP2D for the combination regimen, 
including both safety run-in and dose expansion. Treatment will be administered in 28-day cycles 
until at least one of the study treatment discontinuation criteria are met (Section 3.14). Enrollment 
of subjects in Part B of dose expansion may occur in parallel with enrollment of subjects in Part A
and Part C (SL-172154 administered with azacitidine) of dose expansion. 
3.3.3
Part C: SL-172154 Administered with Azacitidine in AML Subjects with TP53 Gene 
Mutation/Deletion 
Treatment-naïve subjects with AML who have at least one TP53 mutation or deletion will be 
enrolled to receive SL-172154 and azacitidine at a dose and schedule identified in the dose 
escalation part of the study to further evaluate the safety, PD effects, and efficacy of this regimen. 
Prophylactic premedication for IRR with dexamethasone, an antipyretic and antihistamines should 
be administered at least 30 minutes prior to each SL-172154 administration as described in 
Section 3.7.3. The goal is to enroll approximately 20 treatment naïve subjects with TP53 mutant 
AML at the potential RP2D for the combination regimen. Treatment will be administered in 28-
day cycles until at least one of the study treatment discontinuation criteria are met (Section 3.14). 

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Enrollment of subjects in Part C of dose expansion may occur in parallel with enrollment of 
subjects in Part A (SL-172154 administered with azacitidine) and/or Part B (SL-172154 
administered with azacitidine and venetoclax) of dose expansion. 
3.3.4 Part D (Randomized Cohorts): SL-172154 with Azacitidine vs Azacitidine 
monotherapy in HR-MDS Subjects  
Approximately 60 previously untreated subjects with higher-risk (intermediate, high, or very high 
per IPSS-R) MDS will be randomized to three arms (approximately 20 subjects per arm): 3.0 
mg/kg of SL-172154 in combination with azacitidine, 1.0 mg/kg of SL-172154 in combination 
with azacitidine, or azacitidine monotherapy. Subjects will be stratified based on TP53 mutation 
status (TP53m vs TP53wt) and baseline bone marrow blast count
. Prophylactic 
premedication for IRR with dexamethasone, antipyretics and antihistamines should be 
administered at least 30 minutes prior to each SL-172154 administration, as described in Section 
3.7.3. Treatment will be administered in 28-day cycles until at least one of the study treatment 
discontinuation criteria is met (Section 3.14).
3.4
Selection of Recommended Phase 2 Dose (RP2D)
Selection of the RP2D for SL-172154 in combination with azacitidine or in combination with 
azacitidine and venetoclax will be based upon the totality of the safety, tolerability, PK, PD, and 
efficacy data in subjects treated with the respective regimen in dose escalation and dose expansion 
cohorts. The RP2D is a dose of SL-172154 that can be safely administered with azacitidine or 
azacitidine with venetoclax. In addition, preliminary efficacy of the combination regimens will be 
assessed to determine if the regimen warrants further evaluation in a Phase 2 study. 
3.5 
Evaluation of a Less Frequent Dosing Schedule 
If safety and PD data support exploration of a less intensive dosing schedule, then subsequent 
cohort enrollment on an alternative less frequent schedule may be instituted. For example, SL-
172154 may be administered once every two weeks in every cycle or once every 21 or 28 days. 
The starting dose on this less intensive schedule would be instituted at the current dose level of the 
selected schedule that is safe as defined by the mTPI-2 method [Guo, 2017] or a lower dose level
based on emerging safety data. Any such evaluation of alternative dosing schedule(s) will be done 
by protocol amendment. 
3.6 
Definition of Dose-Limiting Toxicity 
Protocol-defined DLT criteria are applicable to the dose escalation portion of the study. The 
determinant period for DLT is the first 28 days of treatment (i.e., Cycle 1). However, there is 
provision in the criteria below for AEs that occur beyond this period to be considered in the 
determination of DLTs and RP2D. All toxicities except for CRS will be graded as per NCI CTCAE 
v5. CRS will be graded per the ASTCT Consensus Grading Criteria for CRS (Section 3.8.2). AEs
clearly related to disease progression, intercurrent illness, or concomitant medications are not 
considered DLTs. Infection, bleeding, or other expected direct complication of cytopenias due to 
active underlying MDS or AML will not be considered a DLT. A DLT is defined as an event 
considered related or possibly related to SL-172154 and meets one of the following criteria: 

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 SL-172154 monotherapy cohorts: Grade 4 neutropenia or thrombocytopenia lasting 14 days 
from the start of the cycle in the absence of evidence of active AML or MDS. 
 SL-172154 in combination with azacitidine or azacitidine and venetoclax: Grade 4 neutropenia 
or thrombocytopenia lasting 
 in the absence of active AML 
or MDS.
Any death not clearly related to underlying disease or intercurrent illness.  
 Any Grade 3 elevations in AST, ALT, or total bilirubin. 
o Evidence of Hy’s Law (AST or ALT  3 x upper limit of normal (ULN) in the setting of 
total bilirubin  2 x ULN without evidence of cholestasis and no other reason can be found 
to explain the combination of increased aminotransferases and total bilirubin, such as viral 
hepatitis A, B or C, preexisting or acute liver disease, or another drug capable of causing 
the observed injury).  
Grade 3 or greater non-hematologic AE that requires permanent discontinuation of SL-172154. 
 Any Grade 3 or greater non-hematologic AE except for those listed below: 
o 
. 
o Grade 3 anorexia, nausea, vomiting or diarrhea provided that it does not require tube 
feeding, total parenteral nutrition, or require or prolong hospitalization. 
o Grade 3 laboratory abnormalities which resolve to Grade 1 or baseline within 72 hours 
with or without intervention.  
o
Grade 3 hypertension that can be controlled (i.e., systolic BP < 140 mmHg and diastolic 
BP < 90 mmHg) with medical therapy. 
o
Vitiligo or alopecia of any grade. 
Other toxicities may be considered a DLT as determined by the Investigator in conjunction with 
the SMC. The DLT-evaluable population is defined in Section 9.2.1. 
3.7
Concomitant Medications, Treatments and Procedures
Investigators may prescribe concomitant medications or treatments deemed necessary to provide 
supportive care except for prohibited medications described in Section 3.7.1. Best supportive care 
should be provided (including but not limited to antibiotics, bisphosphonates, receptor activator of 
nuclear factor kappa B ligand [RANKL] inhibitors, transfusions, growth factor support, nutritional 
support, correction of metabolic disorders, hydration, anti-hyperuricemics, optimal symptom 
control, and pain management including palliative radiotherapy) for all subjects when clinically 
indicated.  
Use of inhaled, topical, intranasal corticosteroids or local steroid injections (e.g., intra-articular 
injection) is permitted. Temporary use of systemic corticosteroids (e.g., prior to computed 
tomography [CT] to prevent contrast allergies) is acceptable. 
Vaccines for Coronavirus Disease 2019 (COVID-19) are permitted as they are not live attenuated 
vaccines. If administered, COVID-19 vaccines should not be administered on the same day as any 
of the study medications; please discuss with the Medical Monitor regarding the timing of 
COVID-19 vaccine administration during this study. 

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3.7.1
Prohibited Medications or Treatments
Subjects must be instructed not to take any medications, including over-the-counter products 
without first consulting with the Investigator. The following medications are prohibited during 
SL-172154 therapy:
Any investigational anti-cancer therapy not described in this protocol.
Any concurrent chemotherapy (other than study medications), radiotherapy, hormonal or 
hormonal suppression therapy, immunotherapy, or biologic therapy administered for anti-
cancer treatment.
 Non-steroidal immunosuppressive medications (except to treat a drug-related AE).
Systemic corticosteroids > 10 mg of daily prednisone or equivalent except that the following 
are permitted:
o
Topical, intranasal, inhaled, ocular, intraarticular corticosteroids.
o Physiological doses of replacement steroid (e.g., for adrenal insufficiency). 
o A brief course of corticosteroids for prophylaxis (e.g., contrast dye allergy) or for 
treatment of non-autoimmune conditions (e.g., transfusion reactions, delayed-type 
hypersensitivity reaction caused by contact allergen). 
o Treatment for a drug-related AE (Section 3.8). 
o Corticosteroids used as prophylactic premedication for IRR.  
 Live attenuated vaccines during the study through 30 days after the last dose of SL-172154. 
 Adalimumab (Humira) should be avoided when subjects receive azacitidine. 
 For venetoclax cohorts:  
o Use of P-gp substrates concomitantly with venetoclax. If concomitant use of P-gp 
substrate is unavoidable, separate dosing of the P-gp substrate by at least 6 hours before 
venetoclax administration.  
o When azole antifungals that are P-gp inhibitors must be used, they are permitted. If 
concomitant use of P-gp inhibitor is unavoidable, venetoclax dose should be reduced as 
described in Section 16.7, or follow country-specific prescribing information (e.g., USPI, 
SmPC, or Product Monograph).  
o When azole antifungals that are strong or moderate CYP3A inhibitors must be used, they 
are permitted. If strong or moderate CYP3A inhibitors must be used, the venetoclax dose 
should be reduced as described in Section 16.7 or follow the country’s current prescribing 
information (e.g., USPI, SmPC, or Product Monograph).  
o Concomitant use of strong or moderate CYP3A inducers is to be avoided throughout the 
study treatment period. Treatment with a strong or moderate CYP3A inducers should stop 
7 days prior to first dose of study treatment.  
3.7.2 Medications To Be Used With Caution 
SL-172154 is a therapeutic protein that may induce the transient release of cytokines including 
IL-6 which in turn, may inhibit the activity of cytochrome P450 (CYP450) enzymes including 
CYP3A4 activity [Evers, 2013]. Although not tested clinically, a drug-drug interaction may occur 
with the co-administration of medications that are CYP450 substrates. Drugs metabolized by 
CYP450 enzymes may have reduced clearance or an increase in half-life or peak plasma 

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concentration, therefore such drugs with a narrow therapeutic index should be used with caution. 
There may be an increased risk of side effects for drugs that are CYP450 substrates. Where 
possible consider substitutions for these medicinal products if therapeutic effects cannot be 
monitored. 
A list of drugs that are CYP450 substrates including CYP3A substrates is available at: https://drug-
interactions.medicine.iu.edu/Main-Table.aspx (Flockhart Table). 
For subjects receiving venetoclax, concomitant use with a P-gp inhibitor or a strong or moderate 
CYP3A inhibitor should be avoided and alternative medications should be considered. In situations 
where the use of strong and moderate CYP3A inhibitors or P-gp inhibitors is not avoidable, the 
venetoclax dose should be reduced as described in Section 16.7, or follow country-specific 
prescribing information.
Subjects receiving venetoclax should avoid grapefruit products, Seville oranges, and starfruit 
during treatment as they contain inhibitors of CYP3A. Refer to the country’s current prescribing 
information of venetoclax (e.g., USPI, SmPC, or Product Monograph) for contraindications and 
dose modifications for use with CYP3A inhibitors and inducers, and P-gp inhibitors.
3.7.3
Prophylactic Premedication for Infusion-Related Reactions (IRR) (All Subjects)
Prophylactic premedication for IRR with dexamethasone 8 mg IV, an antipyretic and 
antihistamines [e.g., acetaminophen 650 to 1000 mg PO; diphenhydramine 25 to 50 mg (or 
equivalent) PO or IV; famotidine 20 mg PO or IV (or equivalent)] should be administered at least 
30 minutes prior to each SL-172154 administration. The dose and administration method of 
prophylactic premedication can be modified at the Investigator’s discretion.  Premedication with 
dexamethasone 8 mg, IV or oral, one day prior to scheduled day of SL-172154 infusion is also 
allowed at the Investigator’s discretion. 
For subjects who experience IRR, see the toxicity management guidelines Section 3.8.1. If the 
measures implemented in study SL03-OHD-104 (prophylaxis noted above and extended duration 
of infusion) are not sufficient for prevention of IRRs, the SMC may recommend modifications of 
prophylactic premedication for IRR based on emerging safety.
3.7.4
Prophylactic Premedication for Cytokine Release Syndrome (CRS)
For subjects who experienced CRS, see the toxicity management guidelines of CRS in 
Section 3.8.2.  
3.7.5 Recommendations for Prophylaxis and Management of Tumor Lysis Syndrome 
(Subjects Receiving Venetoclax) 
There is a potential risk for TLS in subjects with AML who receive venetoclax, especially in those 
with elevated leukocyte count, circulating blasts, elevated pretreatment lactate dehydrogenase 
(LDH) levels, renal dysfunction, and dehydration. In addition, on-target effect of venetoclax could 
lead to rapid cell death and pose a risk for TLS. Subjects enrolled in the study who will receive 
venetoclax should be assessed for the risk of TLS, and to mitigate risk, TLS prophylaxis and 
monitoring may be implemented. Prophylactic reductions of potassium, inorganic phosphorus or 
uric acid above normal range are recommended prior to beginning study treatment and continue 

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based on the ongoing risk of TLS. Below are the minimum recommendations for TLS prophylaxis 
and management for subjects receiving venetoclax in this study. Prophylaxis and monitoring 
procedures for TLS should be implemented as per regional guidelines or institutional standards: 
Consider hospitalization on or before Cycle 1 Day1 prior to administration of the initial 
dose of venetoclax-containing study treatment regimen and remain in the hospital for at 
least 24 hours after reaching the final dose level of the concurrent administration of 
venetoclax/azacitidine in Cycle 1.
Administration of uric acid reducing agent, adequate oral and IV hydration while 
monitoring the fluid status of the subject prior to and during the ramp-up of venetoclax in 
the first cycle should be based on institutional guidelines.
 TLS chemistry tests may be drawn (calcium, inorganic phosphorus, potassium, uric acid 
and creatinine) on the first, second and third day of venetoclax dosing at predose (within 
4 hours prior to dosing), 6 to 8 hours post-dose, and 24 hours after reaching final dose. 
 Additional laboratory assessments may be performed, per Investigator discretion, 
post-dose during ramp-up and up to 48 hours after reaching the final dose (i.e., 400 mg) if 
clinically indicated. 
 Abnormal chemistry tests should be corrected promptly, 
 If a subject meets criteria for clinically significant laboratory of clinical TLS (Table 4), no 
additional venetoclax should be administered until resolution. 
For continued dosing of venetoclax, monitoring for evidence of TLS during treatment and 
managing abnormalities of serum creatinine, uric acid and electrolytes promptly is recommended. 
For subjects at higher risk (i.e., circulating blasts) more intensive measures should be considered.  
Refer to Section 16.4 for recommended guidelines on the management of TLS. 

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Table 4 
Tumor Lysis Syndrome Classification 
Metabolic 
Abnormality
Criteria for Classification of 
Laboratory of TLSa
Criteria for Classification 
of Clinical TLSb
Hyperuricemia 
Uric acid > 8.0 mg/dL (475.8 µmol/L)
N/A 
Hyperphosphatemia
Phosphorus > 4.5 mg/dL (1.5 
mmol/L)
N/A
Hyperkalemia 
Potassium > 6.0 mmol/L
Cardiac dysrhythmia or sudden death 
probably or definitely caused by 
hyperkalemia 
Hypocalcemia
Corrected calcium < 7.0 mg/dL (1.75 
mmol/L) or ionized calcium < 4.5
mg/dL (1.12 mmol/L)c
Cardiac dysrhythmia, sudden death, 
seizure, neuromuscular irritability (tetany, 
paresthesias, muscle twitching, 
carpopedal spasm, Trouseau’s sign, 
Chvostek’s sign, laryngospasm, 
bronchospasm), hypotension, or heart 
failure probably or definitely caused by 
hypocalcemia 
Acute kidney injuryd 
N/A
Increase in the serum creatinine level of 
0.3 mg/dL (26.5 µmol/L) or the presence 
of oliguria (average urine output of 
< 0.5 mL/kg/hr over a 6-hour period)
a.
Laboratory TLS requires two or more metabolic abnormalities must be present during the same 24-hour period within 3 
days before the start of therapy or up to 7 days afterward. 
b. 
Clinical TLS requires the presence of laboratory TLS plus one or more findings from clinical TLS column. 
c. 
Corrected calcium = measure calcium level in mg/dL + 0.8 x(4-albumin in g/dL). 
d. 
Acute kidney injury, unless attributable to another cause, represents clinical TLS even if criteria for laboratory TLS are not 
satisfied. 
Abbreviations: TLS = tumor lysis syndrome; N/A = not applicable 
Source: [Howard, 2011]  
3.8
Toxicity Management Guidelines for SL-172154 
The toxicity management guidelines provided in this section represent general guidance for AEs 
that are considered by the Investigator to be possibly related or related to treatment with 
SL-172154. These guidelines are not meant to be prescriptive, and Investigators should always use 
clinical judgement in the determination of dosing. Investigators should always err on the side of 
caution if treatment-related toxicity is suspected. Subjects should be thoroughly evaluated to rule 
out any alternative etiology (e.g., disease progression, concomitant medications, infections). In the 
absence of a clear alternative etiology, the possibility of an immune-related AE should be 
considered.  
Table 5 describes the dose reductions to be used for AEs that are considered by the Investigator to 
be possibly related or related to treatment with SL-172154. Only one level dose reduction is 

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If further symptoms are not experienced for the next 2 doses of SL-172154, the dose of SL-172154 (if decreased to one dose level 
lower) may be re-escalated to the original dose and the infusion rate may be escalated at intervals and increments as clinically 
appropriate. The investigator may discontinue SL-172154 in the event of recurrent IRR based on the severity of the symptoms.
 
 

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Grade 2 
Interrupt SL-172154.
Vital signs should be measured approximately every 15 minutes for the first hour after discontinuation of SL-172154 infusion and 
then approximately every 30 minutes for the second hour. Monitor subjects with close observation in an outpatient or inpatient 
setting for a minimum of 12 hours or until recovery from symptoms. Consider admission to hospital for management of symptoms,
organ dysfunction or administration of therapy. 
 Closely monitor cardiac and other organ functions. 
 Monitor subjects with continuous cardiac telemetry and pulse oximetry. 
 Start IV infusion with normal saline. Administer oxygen if needed. Treat with an antipyretic, H1/H2 antagonists (diphenhydramine 
50 mg IV plus famotidine 20 mg IV), and/or methylprednisolone 1-2 mg/kg or equivalent dose of corticosteroid every 6 hours and 
manage per institutional guidelines. 
o
If corticosteroids are initiated, continue corticosteroids for at least 3 doses or until complete resolution of symptoms, and
consider corticosteroid taper. 
Consider opioids (e.g., meperidine) for rigors. 
 Consider tocilizumab use for subjects with persistent signs and symptoms after interrupting SL-172154 and after corticosteroid 
treatment for CRS. 
o Administer tocilizumab at a dose of 8 mg/kg over 1 hour (not to exceed 800 mg).  
o Repeat tocilizumab every 8 hours as needed if not responsive to intravenous fluids or increasing supplemental oxygen.  
o Limit to a maximum of 3 doses in a 24-hour period; maximum total of 4 doses. 
 Subjects with extensive comorbidities or those of older age should be treated as for Grade 3. Subjects with worsening symptoms 
should be treated as for Grade 3. 
Resume SL-172154 at one dose level lower when all symptoms/ clinical features for CRS resolved and follow the guidelines below: 
Subjects who have experienced Grade 2 CRS with C1D1 should be hospitalized for C1D8 and C1D15 dosing [SL-172154 
monotherapy cohort] or those who have experienced Grade 2 CRS with C1D2 should be hospitalized for C1D9 and C1D16 
dosing [Combination cohorts], or next two subsequent infusions of SL-172154 after the first event of Grade 2 CRS. Subjects 
should be under prolonged observation for a minimum of 12 hours after the completion of the infusion.
For subsequent infusions, infuse SL-172154 for at least twice the infusion time (± 15 minutes) Premedicate with 
dexamethasone 20 mg, antipyretic, H1/H2 antihistamines, and manage per institutional guidelines.

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Grade 3 
Interrupt SL-172154.
o Permanently discontinue SL-172154 if CRS does not resolve within 72 hours with management. 
 Vital signs should be measured approximately every 15 minutes for the first hour after discontinuation of SL-172154 infusion 
and then approximately every 30 minutes for the second hour. Hospitalization required for management of symptoms related 
to organ dysfunction: admit to the hospital for close monitoring and management. 
 Monitor subjects with continuous cardiac telemetry and pulse oximetry.  
 Consider performing an echocardiogram to assess cardiac function.  
 Treat hypotension with IV fluid for blood pressure support and/or pressers. Administer oxygen for treatment of hypoxia. 
Cryoprecipitate or fresh frozen plasma may be required for coagulopathy. Manage per institutional guidelines. 
 Implement additional management per institutional standards (e.g., epinephrine, diphenhydramine, famotidine, 
corticosteroids, bronchodilators, oxygen, fluids, meperidine for rigors, etc.). Epinephrine is the drug of choice in an 
anaphylactic reaction and its administration should not be delayed. 
 Administer tocilizumab at a dose of 8 mg/kg over 1 hour (not to exceed 800 mg).  
o Repeat tocilizumab every 8 hours as needed if not responsive to intravenous fluids or increasing supplemental 
oxygen. 
o
Limit to a maximum of 3 doses in a 24-hour period; maximum total of 4 doses. 
Second-line therapies: 
o
Methylprednisolone 2 mg/kg/day IV. If corticosteroids are initiated, continue corticosteroids for at least 3 doses or 
until complete resolution of symptoms, and consider corticosteroid taper. For subjects with severe neurologic 
symptoms, consider using dexamethasone due to more efficient penetration of the blood-brain barrier.  
o anti-TNF-
-
-1R-based inhibitors (anakinra). 
Resume SL-172154 at one dose level lower only when all symptoms/ clinical features for CRS resolve within 72 hours and follow the 
guidelines below: 
Subjects who have experienced Grade 3 CRS with C1D1 should be hospitalized for C1D8 and C1D15 dosing [SL-172154 
monotherapy cohort], or those who have experienced Grade 3 CRS with C1D2 should be hospitalized for C1D9 and C1D16 
dosing [Combination cohorts],or next two subsequent infusions of SL-172154 after the first event of Grade 3 CRS. Subjects 
should be under prolonged observation for a minimum of 12 hours after the completion of the infusion.
For subsequent infusions, infuse SL-172154 for at least twice the infusion time (± 15 minutes) (Premedicate with 
dexamethasone 20 mg, antipyretic, H1/H2 antihistamines, and manage per institutional guidelines.

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Grade 4 
Permanently discontinue SL-172154.
Hospitalization required for management of symptoms related to organ dysfunction: admit to the hospital for close monitoring and 
management.
 Vital signs should be measured approximately every 15 minutes for the first hour after discontinuation of SL-172154 infusion and 
then approximately every 30 minutes for the second hour.
 Consider intensive-care supportive therapy. 
 Monitor subjects with continuous cardiac telemetry and pulse oximetry.  
 Consider performing an echocardiogram to assess cardiac function.  
 Treat hypotension with IV fluid for blood pressure support and/or pressers. Administer oxygen for treatment of hypoxia. 
Cryoprecipitate or fresh frozen plasma may be required for coagulopathy. Manage per institutional guidelines. 
 Implement additional management per institutional standards (e.g., epinephrine, diphenhydramine, famotidine, corticosteroids, 
bronchodilators, oxygen, fluids, meperidine for rigors, etc.). Epinephrine is the drug of choice in an anaphylactic reaction and its 
administration should not be delayed. 
Administer tocilizumab at a dose of 8 mg/kg over 1 hour (not to exceed 800 mg). 
o
Repeat tocilizumab every 8 hours as needed if not responsive to intravenous fluids or increasing supplemental oxygen. 
o Limit to a maximum of 3 doses in a 24-hour period; maximum total of 4 doses. 
 Second-line therapies:  
o Methylprednisolone 2 mg/kg/day IV. If corticosteroids are initiated, continue corticosteroids for at least 3 doses or until 
complete resolution of symptoms, and consider corticosteroid taper. For subjects with severe neurologic symptoms, 
consider using dexamethasone due to more efficient penetration of the blood-brain barrier.  
o
anti-TNF-
-
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Grade 4 
Permanently discontinue SL-172154.
Consider hospitalization; obtain hepatology consult; assessments as above; monitor liver function daily; consider liver biopsy. 
If an immune etiology is suspected, immediately start methylprednisolone 1-2 mg/kg (start with 2 mg/kg for Grade 4) or equivalent.
 If refractory after 3 days, consider mycophenolate mofetil (MMF). Avoid the use of infliximab in immune mediated hepatitis.
 

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3.10
Toxicity Management Guidelines for Azacitidine and Venetoclax  
When toxicity is considered to be attributed to the combination of azacitidine and venetoclax, 
dosage modification should follow the current country’s prescribing information (e.g., USPI, 
SmPC, or Product Monograph). Recommendations for management of cytopenias are outlined in 
Section 16.6; if the country-specific prescribing information is different, those current guidelines 
should be used. Please also see Management of Tumor Lysis Syndrome in Section 3.7.5. 
3.11 
Participant Withdrawal of Consent 
A participant may withdraw consent for participation in this study at any time at his/her own 
request; or may be withdrawn at any time at the discretion of the Investigator for safety, 
behavioral, compliance, or administrative reasons. The latter is expected to be uncommon. The 
subject may withdraw consent from further treatment on the study and continue in the survival 
follow-up portion of the study or may withdraw consent from further participation in the study 
(e.g., permanently discontinue study treatment, any follow-up study procedures, no longer be 
contacted for survival). 
At the time of withdrawal of consent for further treatment with study medication, a Post
Treatment visit should be conducted, as shown in the Schedule of Assessments (SOA) in 
Section 6. See SOA for data to be collected at the time of discontinuation of study treatment 
and for any further evaluations that need to be completed. Every effort must be made to 
continue follow-up of participants for protocol-specified safety follow-up procedures to 
capture AEs, SAEs, and unanticipated problems. 
 If the participant withdraws consent for disclosure of future information, the Sponsor may 
retain and continue to use any data collected before such a withdrawal of consent. 
 If a participant withdraws from the study, he/she may request destruction of any samples taken 
and not tested, and the Investigator must document this in the site study records. 
3.12 
Lost to Follow-up 
A participant 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 should be taken if a participant fails to return to the clinic for a required 
study visit: 
o The site must attempt to contact the participant and reschedule the missed visit as soon as 
possible and counsel the participant on the importance of maintaining the assigned visit 
schedule and ascertain whether the participant wishes to and/or should continue in the 
study. 
o Before a participant is deemed lost to follow-up, the Investigator or designee should make 
every effort to regain contact with the participant (where possible, 3 telephone calls and, if 
necessary, a certified letter sent to the participant’s last known mailing address or local 
equivalent methods). These contact attempts should be documented in the participant’s 
medical record. 
o Should the participant continue to be unreachable, he/she will be considered as lost to 
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3.13
Premature Termination or Suspension of the Study 
The Sponsor reserves the right to close the study site or terminate the study at any time for any 
reason. Written notification, documenting the reason for study suspension or termination, will be 
provided by the Sponsor to Investigators and the country regulatory agencies as required. If the 
study is prematurely terminated or suspended, the Investigator will promptly inform the 
Institutional Review Board/Independent Ethics Committee (IRB/IEC) and will provide the 
reason(s) for the termination or suspension. Study sites will be closed upon study completion. A 
study site is considered closed when all required documents and study supplies have been collected 
or destroyed 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 participants by the Investigator 
 Discontinuation of further development of the investigational product (IP) 
 Determination of unexpected, significant, or unacceptable risk to participants 
3.14
Study Treatment Discontinuation Criteria
Subjects will receive the assigned study treatment (e.g., SL-172154 monotherapy or SL-172154
and azacitidine administered with or without venetoclax, or azacitidine monotherapy) until any of 
the following events occur during the study:
Documented disease progression
A subject suffers an AE that, in the judgement of the Investigator, Sponsor, or medical 
monitor, presents an unacceptable risk to the subject
General or specific changes in the subject’s condition (e.g., a significant intercurrent illness 
or complication) that, in the judgement of the Investigator, are unacceptable for further 
administration of study treatment
Subject decision to withdraw from further treatment on the study
Subject becomes eligible for and consents to transplant
Occurrence of pregnancy
Significant noncompliance with protocol requirements
Death
Termination of the study by the Sponsor
A subject meeting the response criteria of relapsed or progressive disease, or determination of 
clinical progression is considered a sufficient reason to discontinue study drug treatment. 
However, if the determination of progression is equivocal for a subject with AML, the 
Investigator may continue study drug treatment when a subject with transfusion dependence at 
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is defined by transfusion requirement during the 4-week period prior to the first dose of study 
drug treatment.  Post-
days at any time point after the first dose of study drug treatment. When the determination of 
progression is equivocal for a subject with MDS, the investigator may continue study drug 
treatment until relapse/ disease progression is confirmed after 4 weeks from an initial finding 
unless there is clinical deterioration.
In the event of study treatment discontinuation, subjects should be strongly encouraged to 
complete all scheduled assessments at the Post Treatment visit and the Survival Follow-up 
contacts.
3.15
Duration of Follow-Up
Subjects who are withdrawn from study treatment for unacceptable AE(s) should be followed until 
the event(s) are resolved, the subject is lost to follow-up, the AE is otherwise explained, or further 
recovery is not deemed to be feasible. Data on these events should be collected on the AE eCRF.
Participants who permanently discontinue IP for reasons other than progression will continue with 
disease assessments until progression or start of another anti-cancer therapy. 
Participants who discontinue IP for any reason other than withdrawal of consent will be followed 
for survival and will be contacted approximately every 3 months until death or the end of the study, 
whichever occurs first. During Survival Follow-up, relevant information regarding subsequent 
anticancer therapy(ies) for AML or MDS will be collected and entered in the eCRF.
In addition, for subjects that proceed to HCT, HCT-relevant information will be collected and 
entered in the eCRF. Refer to Section 6.13 for additional details. 
3.16 
End of Study Definition 
The end of study is defined as the point of final data capture (e.g., the point at which all required 
data has been collected to answer the research questions in the protocol) or date the study is closed 
by the Sponsor, whichever occurs first. 
After the end of study, subjects who are still on study treatment will receive standard of care 
treatment as determined by their health care provider after completion of the study.
3.17
COVID-19 Risk Assessment
Shattuck Labs has developed a separate COVID-19 risk assessment policy to address conduct of 
clinical trials during the COVID-19 pandemic to ensure subject safety as well as management of 
potential implications to data integrity. A copy of this document is available upon request. 
4. 
STUDY POPULATION  
Participants with higher-risk MDS or AML described below may be considered for enrollment in 
the study if they meet all the eligibility criteria stated in Sections 4.1 and 4.2. Prospective approval 
of protocol deviations to recruitment and enrollment criteria, also known as protocol waivers or 
exemptions, is not permitted.  

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4.1
Inclusion Criteria
Participants must meet the following criteria:
1. Subject has voluntarily agreed to participate by giving written informed consent in 
accordance with ICH/GCP guidelines and applicable local regulations. 
2. Age  18 years.  
3. For subjects with AML, confirmation of AML diagnosis by 2016 WHO criteria [Arber, 
2016] (WHO classification, excluding acute promyelocytic leukemia [APL]).  
4. Subjects with MDS must have: 
a.
morphologically confirmed diagnosis of MDS by 2016 WHO criteria [Arber, 2016]
with <20% blasts in bone marrow per bone marrow biopsy/aspirate or peripheral 
blood.  
b. confirmation of intermediate, high or very high risk category by IPSS-R.  
Subjects with a diagnosis of any of the following are excluded: Atypical CML, juvenile 
myelomonocytic leukemia (JMML), chronic myelomonocytic leukemia (CMML), and 
unclassifiable MDS/myeloproliferative neoplasm (MPN). 
5. [Dose Escalation Cohort – SL-172154 Monotherapy] Subjects with AML must have 
relapsed/refractory disease (>5% blasts by manual aspirate differential, flow cytometry, or 
immunohistochemistry) following at least 1 prior line of therapy but no more than 4 prior 
lines of therapy. Subjects with higher-risk MDS must have relapsed/refractory disease 
following at least 1 prior line of therapy but no more than 4 prior lines of therapy.  
a. Prior hydroxyurea or other supportive care in the form of transfusions or growth 
factors will not be considered prior therapy. 
b. Subjects who have undergone allogeneic-HCT are eligible if they are at least 6 months 
post-HCT, have relapsed AML or MDS as defined above, are not on treatment or 
prophylaxis for graft versus host disease (GVHD) for at least 6 weeks before the first 
dose of study treatment, and have no active GVHD. 
c.
Subjects must not be eligible for rescue chemotherapy and allogeneic-HCT per local 
or institutional guidelines at the time of screening.
6. [Dose Escalation Cohort – SL-172154 Administered with Azacitidine] Subjects with
relapsed/refractory AML and MDS (as defined in Inclusion criterion 5) following at least 
1 prior line of therapy but no more than 4 prior lines of therapy.  
a. Treatment for MDS preceding secondary AML will not be considered as a prior line 
of therapy for secondary AML. 
b. Prior hydroxyurea or other supportive care in the form of transfusions or growth 
factors will not be considered prior therapy.  
c.
Subjects who have undergone allogeneic-HCT are eligible if they are at least 6 months 
post-HCT, have relapsed AML or MDS as defined above, are not on treatment or 
prophylaxis for GVHD for at least 6 weeks before the first dose of study treatment, 
and have no active GVHD. 
d. Subjects must not be eligible for rescue chemotherapy and allogeneic-HCT per local 
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In addition, previously untreated subjects meeting either of the following criteria are 
eligible for this cohort: 
a. Previously untreated subjects with AML with known adverse cytogenetics who fall 
into the adverse ELN risk group and who are unlikely to benefit from standard 
intensive induction therapy or refuse intensive induction therapy at time of 
enrollment. 
b. Previously untreated subjects with MDS with documentation of at least one TP53 
gene mutation or deletion based on local test. Prior MDS therapy with lenalidomide
or other supportive care in the form of transfusions or growth factors is allowed. 
7. [Dose Expansion Cohort Part A: SL-172154 Administered with Azacitidine]: Subjects 
diagnosed with MDS must be previously untreated. Prior MDS therapy with lenalidomide, 
luspatercept or other supportive care in the form of transfusions or growth factors is 
allowed. Up to 1 cycle of prior therapy with a hypomethylating agent is permitted. Subjects 
with newly diagnosed treatment-related MDS are also eligible for enrollment. 
8. [Dose Escalation – Safety Run-in Cohort AND Dose Expansion Cohort Part B: SL-172154 
Administered with Azacitidine and Venetoclax]: Subjects with AML must be previously 
untreated as defined by: 
a. Subject must be ineligible for induction therapy with a standard cytarabine and 
anthracycline induction regimen due to age or co-morbidities as defined by the 
following: 
 
 75 years of age  
 
-morbidities:
o Eastern Cooperative Oncology Group (ECOG) Performance Status of 2  
o History of congestive heart failure (CHF) requiring treatment 
o 
 
o Chronic stable angina 
o 
 
o
o
Documented contraindication to anthracycline or cytarabine based therapy
b. Subjects with AML with known adverse cytogenetics who fall into the adverse 
ELN risk group and who are unlikely to benefit from standard intensive induction 
therapy or refuse intensive induction therapy at time of enrollment are also eligible. 
c.
Subjects with newly diagnosed secondary AML and who are unlikely to benefit 
from standard intensive induction therapy or refuse intensive induction therapy at 
time of enrollment are eligible for enrollment. Subjects with secondary AML after 
MDS must not have received prior chemotherapy or no more than 2 cycles of prior 
hypomethylating agent for MDS. 
9. [Dose Expansion Cohort Part C: SL-172154 Administered with Azacitidine]: Subjects with 
previously untreated de novo AML or secondary AML with TP53 gene mutation or 
deletion and who are unlikely to benefit from standard intensive induction therapy or refuse 
intensive induction therapy at time of enrollment are eligible. All subjects must have 

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16. [Dose Expansion Cohort Part D: SL-172154 Administered with Azacitidine vs azacitidine 
monotherapy]: Subjects diagnosed with MDS must be previously untreated. Prior MDS 
therapy with lenalidomide, luspatercept or supportive care in the form of transfusions or 
growth factors is allowed. No prior therapy with a hypomethylating agent is permitted. 
Subjects with newly diagnosed treatment-related MDS are also eligible for enrollment. 
TP53 mutation status results based on local test must be available prior to randomization. 
4.2 
Exclusion Criteria 
Participants are excluded from the study if any of the following criteria apply: 
1. [Monotherapy and Combination Regimen Dose Escalation Cohorts]: Prior treatment with: 
 CAR-T cell therapy within 3 months from the first dose of the study drug.  
 Prior treatment with anti-CD47 targeting agent or CD40 agonist within 28 days prior 
to first dose of study treatment.  
 Prior treatment with signal-
-targeting agent. 
 Other experimental therapies for AML or MDS within 14 days or at least 5 half-lives
(whichever is shorter) prior to first dose of study treatment. 
2. Evidence of active CNS involvement with leukemia. 
3. Subjects requiring agents other than hydroxyurea to control blast counts within 14 days 
prior to first dose of study treatment. 
4. Evidence of active bleeding or bleeding diathesis or major coagulopathy (including 
familial). 
5. [Only for Cohorts Including Venetoclax in the Regimen] Subject has received strong and/or 
moderate CYP3A inducers within 7 days prior to the first dose of venetoclax. 
6. Use of systemic corticosteroids (>10 mg daily prednisone equivalent) or other non-
steroidal immunosuppressive medication, current or within 14 days of the first dose of 
study treatment with the following exceptions (i.e., the following are allowed within 14 
days of first dose): 
 Topical, intranasal, inhaled, ocular, intraarticular corticosteroids 
 Physiological doses of replacement steroid (e.g., for adrenal insufficiency)  
 Steroid premedication for hypersensitivity reactions (e.g., reaction to IV contrast) or 
a brief course of treatment of non-autoimmune conditions (e.g., transfusion reactions, 
delayed-type hypersensitivity reaction caused by contact allergen). 
7. Receipt of live attenuated vaccine within 30 days of first dose of SL-172154 treatment. 
8. Subject has active, uncontrolled infection (e.g., viral, bacterial, or fungal). Subjects are 
eligible if infection is controlled with antibiotics, antivirals and/or antifungals. 
9. [Only for Cohorts Including Venetoclax in the Regimen] Subject has a malabsorption 
syndrome or other condition that precludes enteral route of administration.  
10. Subject with: 

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 Symptomatic peptic ulcer disease or gastritis,  
 active diverticulitis, or  
 other serious gastrointestinal disease associated with diarrhea within 6 months of first 
dose of study treatment. 
11. Clinically significant or uncontrolled cardiac disease including any of the following: 
 Myocarditis
 Unstable angina within 6 months from first dose of study treatment
 Acute myocardial infarction within 6 months from first dose of study treatment  
 Uncontrolled hypertension 
 NYHA Class III or IV congestive heart failure
 Clinically significant (symptomatic) cardiac arrhythmias (e.g., sustained ventricular 
tachycardia, second- or third- degree atrioventricular (AV) block without a 
pacemaker, circulatory collapse requiring vasopressor or inotropic support, or 
arrhythmia not stabilized on therapy) 
12. Subject has chronic respiratory disease that requires continuous oxygen, or significant 
history of renal, neurologic, psychiatric, endocrinologic, metabolic, immunologic, hepatic, 
cardiovascular disease, or any other medical condition that in the opinion of the 
Investigator would adversely affect his/her participation in the study. 
13. Subjects who have had any major surgical procedure within 14 days of first dose of study 
treatment. 
14. Subject is a woman who is pregnant or breast feeding or planning to become pregnant or 
breast feed while receiving study treatment in this study.
15. Psychiatric illness/social circumstances that would limit compliance with study 
requirements and substantially increase the risk of AEs or compromise ability to provide 
informed consent. 
16. Presence of another malignancy that requires active therapy and that in the opinion of the 
Investigator and Sponsor would interfere with the monitoring of disease assessments in 
this study.  
17. Known hypersensitivity to any of the study medications including excipients of azacitidine. 
18. Has undergone solid organ transplantation.
19. Known or active human immunodeficiency virus (HIV) infection 
20. Known or active infection with hepatitis B (positive for hepatitis B surface antigen 
[HBsAg]) or hepatitis C virus ([HCV]; if HCV antibody (Ab) test is positive check for 
HCV ribonucleic acid [RNA]).  
NOTE: Hepatitis B virus (HBV): Subjects who are hepatitis B core antibody (HbcAb)-
positive, but HbsAg-negative are eligible for enrollment. HCV: Subjects who are HCV Ab-
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Secondary packaging / Quality / Label 
type
This is an open label study. Each vial of SL-172154 will be 
supplied in a single vial carton. See SPM for details.
Manufacturer / Source of procurement
Manufactured for Shattuck Labs by 
 
SL-172154 will be provided to sites by the Sponsor. The contents of the label will be in accordance 
with all applicable regulatory requirements.
5.1.2
Preparation, Handling, and Storage of SL-172154
5.1.2.1
Preparation
Standard aseptic technique, including preparation of doses in a laminar flow hood, is required. 
SL-172154 solution 10 mg/mL is supplied as a frozen liquid. Before use, thaw each vial of 
SL-172154 solution 10 mg/mL overnight under refrigerated conditions, protected from light, or at 
room temperature until completely thawed. Following thawing, gently swirl the vial to ensure 
uniformity. Only sterile normal saline (0.9%) should be used to dilute SL-172154. See the SPM 
for further details on the preparation of SL-172154.
5.1.2.2
Handling
Under normal conditions of handling and administration, SL-172154 is not expected to pose 
significant safety risks to site staff. A Safety Data Sheet (describing the occupational hazards and 
recommended handling precautions) will be provided to site staff if required by local laws or will 
otherwise be available from the Sponsor upon request. 
In the case of unintentional occupational exposure notify the Sponsor and consult the SPM. 
Refer to the SPM for detailed procedures for the disposal and/or return of unused SL-172154. 
5.1.2.3 
Storage 
SL-172154 must be stored in a secure area under the appropriate physical conditions for the 
product. Access to and administration of SL-172154 drug product will be limited to the 
Investigator and authorized site staff. SL-172154 must be dispensed or administered only to 
subjects enrolled in the study and in accordance with the protocol.  
SL-172154 drug product vials are to be stored frozen at a temperature -75°C ± 10°C. Please see 
SPM for guidance on temperature excursions outside of this range. Maintenance of a temperature 
log is required. The drug product should be stored protected from light. 
The expiry date will be on the single vial carton label, if required. 
5.1.3 Dosing and Change in Weight 
The actual body weight in kg will be used for SL-172154 dose calculation in all subjects whose 
body weight** is less than or equal to 100 kg. For subjects with body weight >100 kg, the dose to 
be administered should be the same as that calculated for a subject weighing 100 kg. The subject 
should be dosed according to their Cycle 1 Day 1 weight throughout the study (mg/kg) if there is 
no significant change in their weight from the weight recorded at the Cycle 1 Day 1 visit. A change 

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in weight (i.e., increase or decrease) of the subject by 10% OR greater will require re-calculation 
of dose (mg/kg).  
**Subject weight should be per the institutional standard but no less precise than rounded to a 
whole number prior to calculating the dose to be administered (e.g., 72.5 kg should be rounded up 
to 73 kg, 72.4 kg should be rounded down to 72 kg). 
5.1.4 Monitoring Dose Administration 
SL-172154 must be administered in an outpatient oncology treatment center or inpatient unit to 
enable close monitoring of subjects and proactive management of AEs. The risks associated with 
administration of SL-172154 include infusion reactions and CRS as described in Section 1.8.1. 
Therefore, appropriate drugs and medical equipment to treat acute HSRs and monitoring and 
management of CRS must be immediately available, and study personnel must be trained to 
recognize and treat these toxicities. In case an event of CRS should occur, ensure that at least 2 
doses of tocilizumab are available prior to each infusion of SL-172154 (see Section 3.8.2 for 
toxicity management recommendations). When tocilizumab is not available, consider using a drug 
with similar mechanism of actions such as anti-IL-6 receptor mAbs (e.g. sarilumab) or anti-IL-6 
mAbs (e.g., siltuximab).
Subjects will be monitored prior to, during, and for at least 4 hours after the completion of each
SL-172154 infusion. Monitoring time may be shortened to 2 hours at Cycle 4 Day 1 and beyond 
if no IRR or CRS was observed with the last four consecutive doses. Monitoring time after the 
completion of each SL-172154 infusion can be further shortened to 1 hour at Cycle 6 Day 1 and 
beyond if no IRR or CRS was observed with the last four consecutive doses. Vital signs will be 
measured as outlined in the SOA in Section 6 as needed. 
Subjects who are administered azacitidine monotherapy in the control arm of Part D will be 
monitored according to institutional standard of procedures.  
 
5.1.5
Treatment of SL-172154 Overdose
An overdose of SL-172154 is defined as the administration of a dose and/or schedule greater than 
the dose and/or schedule that had been studied to date. If an overdose is suspected, the Investigator 
should contact the Sponsor to confirm the highest dose and schedule tested to date. In the event of 
an overdose of SL-172154, the Investigator should: 
 Closely monitor the subject for AEs/SAEs and laboratory abnormalities for at least 2 weeks 
following the infusion. No information on treatment of overdose of SL-172154 is currently 
available. General supportive measures should be used as appropriate. The appropriate AE 
management guideline should be followed (Section 3.8) where applicable. Pharmacologic 
effect could persist even after SL-172154 is no longer detectable in the serum. Subject 
should have recovered from toxicities that occurred because of the excess dose before the 
next scheduled dose is administered. 
 Overdose itself is not typically considered an AE or SAE. However, if the overdose results 
in an AE, the AE must also be recorded on the AE eCRF. Overdose does not automatically 

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make an AE serious, but if the consequences of the overdose meet the definition of a serious 
event, for example death or hospitalization, the event must be reported as an SAE 
(Section 7.6). 
Obtain a serum sample for PK analysis within 24 hours of the event if requested by the 
Sponsor (determined on a case-by-case basis)
Document the planned and actual dose in the eCRF
Decisions regarding dose interruptions for overdose of SL-172154 will be made by the Investigator 
in consultation with the Sponsor Medical Monitor based on the clinical evaluation of the subject.
5.2
Azacitidine
Azacitidine 75 mg/m2 will be administered either IV (10-40 minute infusion) or subcutaneously 
once daily for 7 days (Days 1 to 7 or alternative 5-2-2 schedule) in 28-day cycles (Table 7 and 
Table 8). Azacitidine is to be administered beginning on Day 1 of each cycle for all subjects, 
regardless of combination regimen cohort assignment. When SL-172154 is to be administered on 
the same day as azacitidine, the azacitidine administration should be completed at least 30 minutes 
prior to the start of the SL-172154 infusion. Refer to the country’s current prescribing information 
of azacitidine (e.g., USPI, SmPC, or Product Monograph). for details regarding preparation, 
handling, administration, storage, instructions, and precautions; subjects should be premedicated 
with anti-emetics for nausea and vomiting. 
Table 7
Azacitidine Dosing During Cycles 1 and 2 
28-day Cycles
D1
D2 
D3 
D4 
D5 
D6 
D7 
D8 
D9 
D16
D23 
SL-172154 dosing 
X 
X 
X
X
Azacitidine dosing (7-day 
schedule) 
X
X 
X 
X 
X 
X 
X 
 
Azacitidine dosing (5-2-2 schedule)
X 
X 
X 
X 
X 
 
 
X
X
On days when both SL-172154 and azacitidine are administered, azacitidine administration should be completed at least 30 
minutes prior to the start of the SL-172154 infusion. 
Table 8 
Azacitidine Dosing During Cycle 3 and Thereafter  
28-day Cycles
D1
D2 
D3 
D4 
D5 
D6 
D7 
D8 
D9 
D16
D23 
SL-172154 dosing 
X 
X
 
Azacitidine dosing (7-day 
schedule) 
X
X
X
X
X
X
X
Azacitidine dosing (5-2-2 schedule)
X 
X 
X 
X 
X 
 
 
X
X
On days when both SL-172154 and azacitidine are administered, azacitidine administration should be completed at least 30 
minutes prior to the start of the SL-172154 infusion. 
5.3
Venetoclax
Venetoclax 400 mg will be administered orally, once daily, with food (Table 9 and Table 10). A 
3-day ramp-up dosing during Cycle 1 will be performed, with the dose of venetoclax 100 mg on 
Day 1 and 200 mg on Day 2; on Day 3, the target dose of 400 mg will be administered and 

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continued until Day 28. In all subsequent 28-day cycles, the dose of venetoclax will be 400 mg 
daily. Subjects will self-administer venetoclax by mouth once daily. Tablets must be swallowed 
whole and must not be broken, chewed, or crushed. Refer to the country’s current prescribing 
information of venetoclax (e.g., USPI, SmPC, or Product Monograph) for details regarding 
preparation, handling, administration, storage, instructions and precautions.  
Table 9 
Venetoclax Dosing During Cycles 1 and 2  
28-Day Cycles 
D1
D2 
D3
D4 D5
D6
D7
D8 
D9 D16
D23
SL-172154 dosing
X
X
X
X
Azacitidine dosing (7-day 
schedule)
X
X
X
X
X
X
X
Azacitidine dosing (5-2-2 
schedule)
X
X 
X
X 
X
 
 
X
X 
Venetoclax PO administration 
3-day ramp-upa,b 
Once daily 
100 
mg 
200 mg
400 
mg 
400 mg
Venetoclax PO administration 
when a strong CYP3A inhibitor is 
co-administered
4-day ramp-upa, b
Once daily 
On days when both SL-172154 and azacitidine are administered, azacitidine administration should be completed at least 30 
minutes prior to the start of the SL-172154 infusion.  
a. 
Chemistry tests should be drawn at predose (within 4 hours prior to dosing of venetoclax), 6 to 8 hours after each new dose 
during ramp-up, and 24 hours after reaching final dose.  
b. 
Note ramp-up is only in Cycle 1.  
Table 10 
Venetoclax Dosing During Cycle 3 and Thereafter
28-Day Cycles
D1
D2 
D3 
D4 
D5 
D6 
D7 
D8 
D9 
D16
D23 
SL-172154 dosing
X
X
Azacitidine dosing (7-day 
schedule) 
X
X
X
X
X
X
X
Azacitidine dosing (5-2-2 schedule)
X 
X 
X 
X 
X 
X 
X 
 
Venetoclax PO administration 
Once daily 
On days when both SL-172154 and azacitidine are administered, azacitidine administration should be completed at least 30 
minutes prior to the start of the SL-172154 infusion. 
5.4
Drug Accountability and Treatment Compliance
Product accountability records must be maintained throughout the course of the study. The 
Investigator or designee is responsible for keeping accurate records of all study drug supplies 
received from the Sponsor, the amount of SL-172154, azacitidine or venetoclax dispensed for 
administration to the subjects and the amount of unused or partially used SL-172154 remaining at 
the conclusion of the trial. An accurate and current accounting of study agents administered to 
each subject must be maintained on an ongoing basis by a member of the study site staff in the 

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Drug Accountability Record throughout the course of the study. Treatment compliance will be 
monitored by drug accountability as well as the subject’s medical record and eCRF. Refer to the 
SPM for further detailed instructions on product accountability. 
When subjects self-administer venetoclax, compliance will be assessed through review of a dosing 
diary. The Investigator or designee should query the subject during clinic visits and document in 
the source documents. A record of the number of tablets dispensed to, taken and returned by each 
subject is to be maintained and reconciled with study treatment and compliance records. The 
Investigator must make every effort to bring non-compliant subjects into compliance. Treatment 
start and stop dates, including dates for treatment delays and/or dose modifications will be recorded 
in the eCRF.
Handling and Disposal: Local requirements for disposal of hazardous drugs should be followed 
at each participating clinical site. It is the Investigator’s responsibility to arrange for disposal of all 
partially used or empty containers, provided that procedures for proper disposal have been 
established according to applicable federal, state, local and institutional guidelines and procedures, 
and provided that appropriate records of disposal are kept. 
Prior to the return or destruction of SL-172154, the Sponsor Study Monitor must have performed 
a complete reconciliation of all drug ensuring accountability records are complete and accurate 
and are retained in the Investigator’s site file or pharmacy file. Study drugs that are returned to the 
supplier or destroyed on site must be documented in the accountability documentation.
Arrangements for the return of SL-172154 or other study agents will be made by the responsible 
Study Monitor.
Refer to the SPM for SL-172154 for further instructions on requirements.
6.
STUDY ASSESSMENTS AND PROCEDURES  
 Study procedures and their timing are summarized in the SOA. Protocol waivers or 
exemptions are not allowed. 
Adherence to the study design requirements, including those specified in the SOA, is 
essential and required for study conduct.
All screening evaluations must be completed and reviewed by the Investigator to confirm 
that potential subjects meet all eligibility criteria. The Investigator will maintain a 
screening log to record details of all subjects screened and to confirm eligibility or record 
reasons for screening failure, as applicable.
Procedures conducted as part of the participant’s routine clinical management (e.g., blood 
count) and obtained before signing of the informed consent form (ICF) may be utilized for 
screening or baseline purposes provided the procedures met the protocol-specified criteria 
and were performed within the timeframe defined in the SOA.  
In the SL-172154 plus azacitidine arm or azacitidine and venetoclax arm, if SL-172154 
dose is held, then the next scheduled dose of azacitidine (and venetoclax) can be 
administered per the schedule, without any delay.
Beginning with Cycle 2, if the start of a subsequent cycle (e.g., Day 1) is delayed due to 
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should also be delayed. Consequently, the current cycle length is extended (i.e., the cycle 
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f. Cardiac Assessments: 12-lead electrocardiogram (ECG) and an echocardiogram (ECHO) or multigated acquisition (MUGA) scan must be performed at screening to serve as a baseline for 
comparison in the event of a cardiac AE/SAE. ECHO/MUGA scan or ECG performed within 30 days of first dose in this study does not need to be repeated during Screening.
g. Blood phenotyping (ABO/Rh) and DAT: will be performed at local laboratories according to the laboratory’s normal procedures. At screening, the following tests will be performed: a) ABO and D 
group (ABO/Rh) type and antibody screen and antibody identification if required, b) DAT, and c) phenotype/genotype for, at a minimum, the minor antigens Rh C/c, E/e, K, Jk, Fy, and MNS. If 
assessment was performed within 21 days and all requested information is available, this can be used for baseline assessment. 
h. Vital Signs: Blood pressure (BP), heart rate (HR), temperature (T) and respiratory rate (RR) must be measured after the subject has been at rest (a semi-supine or sitting position) for at least 5 
minutes (min). Pulse oximetry will be collected to coincide with vital sign time points noted below.
1) Collect vital signs/pulse oximetry during Cycle 1 on D1, D8, D15, D22: Predose (within 30 min of starting the infusion), at the end of infusion (EOI) and then 0.5 hour [hr] (± 5 min), 2 hr (± 10 
min), 4 hr (± 10 min) after the EOI for SL-172154. 
2) Collect vital signs/pulse oximetry dosing days 
: Predose (within 30 min of starting the infusion) and at the end of infusion (EOI) (± 5 min) of SL-172154. 
3) For subjects experiencing any grade IRR,  vital signs should be measured after the onset of an IRR approximately every 15 minutes through the end of the infusion followed by approximately 
every 15 minutes for one hour after end of the SL-172154 infusion and then approximately every 30 minutes for the second hour after end of the SL-172154 infusion. 
i. Pregnancy Test: A serum pregnancy test (beta-
-hCG]) or urine pregnancy test must be performed at screening for all FCBP within 72 hrs of first dose of any study 
drug on Cycle 1 Day 1. FCBP must start using a highly effective method of contraception (i.e., <1% failure rate) at least 14 days prior to initiation of study treatment and continue use during treatment 
and for 30 days (which exceeds 5 half-lives) after the last dose of SL-172154.  
1) Repeat this test every 8 weeks during SL-172154 treatment (i.e., C3D1, C5D1, C7D1, etc. for every 8 weeks; C2D1, C3D1, C4D1, etc.. 
j. Pharmacokinetic (PK)/anti-drug antibody (ADA)/Receptor occupancy (RO): Blood sample collection timings for PK/ADA/RO measurement are outlined in Section 6.1.1 in supplementary Table 
11. Blood volumes required will be provided in the Study Laboratory Manual (SLM). PK/ADA samples should not be collected from infusion port for drug delivery i.e., recommend having a separate 
line in the opposite arm for sample collection.
1) If subject has a positive or unknown ADA test at the Post Treatment visit, an additional blood sample should be collected for ADA and PK assessment within 45-90 days of last dose of study 
treatment. 
k. Cytokines: Blood sample collection timing for cytokine assessments are outlined in Section 6.1.1 in supplementary Table 11. Blood volumes required will be provided in the SLM. Cytokines samples 
should not be collected from infusion port for drug delivery i.e., recommend having a separate line in the opposite arm for sample collection.  
l. Bone marrow aspirate: See Section 8.1 for details regarding bone marrow aspirates for disease assessment during the study. See 6.10 and Table 15 for bone marrow assessment schedule for 
SL-172154 monotherapy for research. 
1) Alternative dates for C2D1, C3D1, C5D1 bone marrow aspirate are available in Table 15 (Section 6.10).
m. SL-172154 administration: Subjects will be monitored prior to, during, and for at least 4 hours after the completion of each SL-172154 infusion. Monitoring time may be shortened to 2 or 1 hours 
in later cycles. See Section 5.1.4 for details. SL-172154 should be administered according to the prescribed dosing schedule in cycle 1 to align with the safety DLT assessment and sample (PK, 
ADA, etc.) collection schedules. Beginning on Cycle 1 Day 9, a window of ± 2 days is allowed for scheduled dosing days for drug administration (NOTE: each dose must be administered at least 5 
days apart from the previous dose). If the start of a subsequent cycle (e.g., Day 1) is delayed, the current cycle length is extended (e.g., the cycle lasts longer than 28 days). 
n. AE Monitoring: After signing of informed consent, but prior to initiation of study medications, only AEs (both serious or nonserious) caused by a protocol-mandated procedure will be collected (e.g., 
AEs related to invasive procedures such as biopsies). Subjects will be followed continuously for AEs during the study and for 30 days after the last dose of SL-172154. After a subject is discontinued 
from SL-172154 due to progressive disease or for other reasons, any ongoing AE should be followed until resolution (or return to baseline) and documented in the eCRF. If another anti-cancer agent 
is started within 30 days after the last dose of SL-172154, only SAEs and AEs that occur prior to the start of the new anticancer therapy should be recorded. In the event of a continuing SAE, the 
subject will be asked to return for follow-up until the SAE has resolved or is deemed to be continuing indefinitely. AEs will be characterized per NCI-CTCAE criteria v5.0 and events recorded in the 
eCRF.  
o. Survival Follow-Up (SFU): All subjects will be contacted after discontinuing study therapy to collect survival status. Subjects should be contacted every 3 months (± 14 days) until death, withdrawal 
of consent, lost to follow-up or end of study. Contact may include clinic visit, telephone contact, email or mail to document survival status. Initiation of any subsequent anti-cancer therapy should 
also be reported. For subjects who proceed to HCT, HCT-relevant information should also be collected and entered in the eCRF. Should the subject be followed by another physician, the study 
Investigator should contact the subject’s hematologist/oncologist/transplant physician to obtain this information. See Section 6.13 for details.

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a. Assessment Window: With the exception of Screening assessments and 
-week intervals will have a ± 3-day window and assessments 
performed at > 4-week intervals will have a ± 1-week window. Laboratory tests can be performed up to 3 days prior to the scheduled dose.
b. Screening: Screening Period extends from Day -21 to Day -1 for routine clinical assessments unless otherwise specified; subjects may complete Screening and initiate dosing on the same day 
provided all Screening assessments are completed and confirmed to meet eligibility requirements prior to receipt of any of the study drugs. The following screening assessments do not need to be 
repeated on Cycle 1 Day 1 if performed within 72 hours of the first dose of study treatment: hematology, clinical chemistry, ECOG status, and physical exam.  
c. Post Treatment visit (PTV): visit should occur 30 days (± 7 days) from the last dose of study treatment. In addition to the assessments to be performed at the Post Treatment Visit, additional 
information, if available, should be collected regarding the subject. Beginning at the Post Treatment Visit and during Survival Follow-up. Initiation of any subsequent anti-cancer therapy should 
also be reported. For subjects who proceed to HCT, HCT-relevant information should also be collected and entered in the eCRF. Should the subject be followed by another physician, the study 
Investigator should contact the subject’s hematologist/oncologist/transplant physician to obtain this information. See Section 6.13for details. 
d. Eligibility evaluation: Subjects must meet all eligibility criteria prior to first dose of any study drug. 
e. Hematology/Clinical Chemistry/Coagulation/Thyroid Function (TSH, free T4)/Antiviral Testing: will be performed at local laboratories according to the laboratory’s normal procedures. See 
Section 6.6.7 for list of laboratory tests required. For subjects receiving venetoclax, chemistry tests to monitor for TLS should also be performed (calcium, inorganic phosphorus, potassium, uric acid 
and creatinine) on the first, second and third day of venetoclax dosing at predose (within 4 hours prior to dosing), 6 to 8 hours after each new dose during ramp-up, and 24 hours after reaching final 
dose. If the modified ramp-up schedule is used with strong CYP3A inhibitors, a uric acid test is required on fourth day of venetoclax dosing. 
1. Additional hematology sample will be collected at 2 hrs after the end of infusion in Cycle 1 on D2, D9 and D16 and on Cycle 2 D2. Microscopic examination of peripheral blood smear per local 
assessment is strongly encouraged for 2 hour-post EOI hematology samples.
2. Hematology will be performed on Day 16 of Cycles 1, 2, 3, 4, 5 and 6 only. 
f. Cardiac Assessments: 12-lead electrocardiogram (ECG) and an echocardiogram (ECHO) or multigated acquisition (MUGA) scan must be performed at screening to serve as a baseline for 
comparison in the event of a cardiac AE/SAE. ECHO/MUGA scan or ECG performed within 30 days of first dose in this study does not need to be repeated during Screening. 
g. Blood phenotyping (ABO/Rh) and DAT: will be performed at local laboratories according to the laboratory’s normal procedures. At screening, the following tests will be performed: a) ABO and D 
group (ABO/Rh) type and antibody screen and antibody identification if required, b) DAT, and c) phenotype/genotype for, at a minimum, the minor antigens Rh C/c, E/e, K, Jk, Fy, and MNS. If 
assessment was performed within 21 days and all requested information is available, this can be used for baseline assessment. 
h. Vital Signs: Blood pressure (BP), heart rate (HR), temperature (T) and respiratory rate (RR) must be measured after the subject has been at rest (a semi-supine or sitting position) for at least 5 
minutes (min). Pulse oximetry will be collected to coincide with vital sign time points noted below. 
1) 
Collect vital signs/pulse oximetry during Cycle 1 on D2, D9, D16, D23: Predose (approximately 30 min of starting the infusion),  then every 15 min (±5 min) during the first hour of infusion, 
every 30 min (±10 min) from second hour onwards through one hour post end of SL-172154 infusion, and 2 hr (± 10 min), 4 hr (± 10 min) after the EOI for SL-172154. 
2) 
 Predose (approximately 30 min of starting the infusion), then every 15 min (±5 min) during the first hour of infusion and every 30 
min (±10 min) from second hour onwards through one hour post end of SL-172154 infusion. 
3) 
For subjects experiencing any grade IRR, vital signs should be measured after the onset of an IRR approximately every 15 minutes through the end of the infusion followed by approximately 
every 15 minutes for one hour after end of the SL-172154 infusion and then approximately every 30 minutes for the second hour after end of the SL-172154 infusion. 
i. Pregnancy Test: A serum pregnancy test (beta-
-hCG]) or urine pregnancy test must be performed at screening for all FCBP within 72 hrs of first dose of any study 
drug on Cycle 1 Day 1. FCBP must start using a highly effective method of contraception (i.e., <1% failure rate) at least 14 days prior to initiation of study treatment, and continue use during treatment 
and for 30 days (which exceeds 5 half-lives) after the last dose of SL-172154, or for the duration required by local prescribing information after the last dose of azacitidine (i.e., for sites in UK, at 
least 6 months after the last dose of azacitidine in either combination regimen).  
1) Repeat this test every 8 weeks during SL-172154 treatment (i.e., C3D1, C5D1, C7D1, etc. for every 8 weeks). 
j. Pharmacokinetic (PK)/anti-drug antibody (ADA)/Receptor Occupancy (RO): Blood sample collection timings for PK/ADA/RO measurement are outlined in Section 6.2.1 in Table 12. Blood 
volumes required will be provided in the SLM. PK/ADA samples should not be collected from infusion port for drug delivery i.e., recommend having a separate line in the opposite arm for sample 
collection. 
1) All subjects should have an additional blood sample collected for ADA assessment within 45-90 days of the last dose of study treatment. 
k. Cytokines: Blood sample collection timing for cytokine assessments are outlines in Section 6.2.1 in Supplementary Table 12. Blood volumes will be provided in the SLM. Cytokines samples should 
not be collected from infusion port for drug delivery i.e., recommend having a separate line in the opposite arm for sample collection. 

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l. Bone marrow aspirate: See Section 8.1 for details regarding bone marrow aspirates for disease assessment during the study. See Section 6.10 and Table 16 for details of the schedule for bone 
marrow assessments for SL-172154 in combination with azacitidine or azacitidine + venetoclax. If a baseline bone marrow sample could not be collected, an archival bone marrow sample (if 
available) should also be provided. In addition, a peripheral blood sample should be collected during screening and submitted for translational or biomarker research. If a peripheral blood sample 
was submitted during screening, on-study peripheral blood samples should also be collected for translational or biomarker research at the time of on-study bone marrow collection (Table 16).
1) Bone marrow aspirate on Day 1 in Cycle 8 and thereafter. 
2) Bone marrow aspirate on Day 2 in Cycle 3 and Cycle 5. 
3) Alternative dates for C2D2, C3D2, C5D2 bone marrow aspirate are available in  Table 16 (Section 6.10). 
m. SL-172154 administration: Subjects will be monitored prior to, during, and for at least 4 hours after the completion of each SL-172154 infusion. Monitoring time may be shortened to 2 or 1 hour in 
later cycles. See Section 5.1.4 for details. SL-172154 should be administered according to the prescribed dosing schedule in Cycle 1 to align with the safety DLT assessment and sample (PK, ADA, 
etc.) collection schedules. Beginning on Cycle 1 Day 9, a window of ± 2 days is allowed for scheduled dosing days for drug administration (NOTE: each dose must be administered at least 5 days 
apart from the previous dose. If the start of a subsequent cycle (e.g., Day 2) is delayed, the current cycle length is extended (e.g., the cycle lasts longer than 28 days). On days when both SL-172154 
and azacitidine study drugs are administered, azacitidine administration should be completed at least 30 minutes prior to the start of the SL-172154 infusion.  
n. AE Monitoring: After signing of informed consent, but prior to initiation of study medications, only AEs (both serious or nonserious) caused by a protocol-mandated procedure will be collected (e.g., 
AEs related to invasive procedures such as biopsies). Subjects will be followed continuously for AEs during the study and for 30 days after the last dose of study medications (SL-172154 and/or 
azacitidine or venetoclax). After a subject is discontinued from SL-172154 or study therapy due to progressive disease or for other reasons, any ongoing AE should be followed until resolution (or 
return to baseline) and documented in the eCRF. If another anti-cancer agent is started within 30 days after the last dose of SL-172154, only SAEs and AEs that occur prior to the start of the new 
anticancer therapy should be recorded. In the event of a continuing SAE, the subject will be asked to return for follow-up until the SAE has resolved or is deemed to be continuing indefinitely. AEs 
will be characterized per NCI-CTCAE criteria v5.0 and events recorded in the eCRF.  
o. Survival Follow-Up (SFU): All subjects will be contacted after discontinuing study therapy to collect survival status. Subjects should be contacted every 3 months (± 14 days) until death, withdrawal 
of consent, lost to follow-up or end of study. Contact may include clinic visit, telephone contact, email or mail to document survival status. Initiation of any subsequent anti-cancer therapy should 
also be reported. For subjects who proceed to HCT, HCT-relevant information should also be collected and entered in the eCRF. Should the subject be followed by another physician, the study 
Investigator should contact the subject’s hematologist/oncologist/transplant physician to obtain this information. See Section 6.13 for details. 
p. Physical Examination: full physical exam is only required at screening and PTV, on treatment physical exams should be performed per standard of care. 
 
 

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be reported. For subjects who proceed to HCT, HCT-relevant information should also be collected and entered in the eCRF. Should the subject be followed by another physician, the study 
Investigator should contact the subject’s hematologist/oncologist/transplant physician to obtain this information. See Section 6.13 for details.
d. Eligibility evaluation: Subjects must meet all eligibility criteria prior to first dose of any study drug.
e. Hematology/Clinical Chemistry/Coagulation/Thyroid Function (TSH, free T4)/Antiviral Testing: will be performed at local laboratories according to the laboratory’s normal procedures. See 
Section 6.6.7 for list of laboratory tests required.  
1. Hematology will be performed on Day 16 of Cycles 1, 2, 3, 4, 5 and 6 only. 
f. Cardiac Assessments: 12-lead electrocardiogram (ECG) and an echocardiogram (ECHO) or multigated acquisition (MUGA) scan must be performed at screening to serve as a baseline for 
comparison in the event of a cardiac AE/SAE. ECHO/MUGA scan or ECG performed within 30 days of first dose in this study does not need to be repeated during Screening. 
g. Vital Signs: Blood pressure (BP), heart rate (HR), temperature (T) and respiratory rate (RR) must be measured after the subject has been at rest (a semi-supine or sitting position) for at least 5 
minutes (min). Pulse oximetry will be collected to coincide with vital sign time points noted below. 
1) 
Collect vital signs/pulse oximetry during Cycle 1 on D2, D9, D16, D23: Predose (approximately 30 min of starting the infusion),  then every 15 min (±5 min) during the first hour of 
infusion, every 30 min (±10 min) from second hour onwards through one hour post end of SL-172154 infusion, and 2 hr (± 10 min), 4 hr (± 10 min) after the EOI for SL-172154. 
2) 
 Predose (approximately 30 min of starting the infusion), then every 15 min (±5 min) during the first hour of infusion and every 
30 min (±10 min) from second hour onwards through one hour post end of SL-172154 infusion. 
3) 
For subjects experiencing any grade IRR, vital signs should be measured after the onset of an IRR approximately every 15 minutes through the end of the infusion followed by approximately 
every 15 minutes for one hour after end of the SL-172154 infusion and then approximately every 30 minutes for the second hour after end of the SL-172154 infusion. 
h. Pregnancy Test: A serum pregnancy test (beta-
-hCG]) or urine pregnancy test must be performed at screening for all FCBP within 72 hrs of first dose on Cycle 1 
Day 1. FCBP must start using a highly effective method of contraception (i.e., <1% failure rate) at least 14 days prior to initiation of study treatment, and continue use during treatment and for 30 
days (which exceeds 5 half-lives) after the last dose of SL-172154, or for the duration required by local prescribing information after the last dose of azacitidine (i.e., for sites in UK, at least 6 months 
after the last dose of azacitidine).  
1) Repeat this test every 8 weeks during SL-172154 treatment (i.e., C3D1, C5D1, C7D1, etc. for every 8 weeks). 
i. Pharmacokinetic (PK)/anti-drug antibody (ADA)/Receptor Occupancy (RO): Blood sample collection timings for PK/ADA/RO measurement are outlined in Section 6.3.1 in Table 13. Blood 
volumes required will be provided in the SLM. PK/ADA samples should not be collected from infusion port for drug delivery i.e., recommend having a separate line in the opposite arm for sample 
collection. 
1) All subjects should have an additional blood sample collected for ADA assessment within 45-90 days of the last dose of study treatment. 
j. Cytokines/Complement Analysis: Blood sample collection timing for cytokine assessments and complement analysis are outlined in Section 6.3.1 in Supplementary Table 13. Blood volumes will 
be provided in the SLM. Cytokines samples should not be collected from infusion port for drug delivery i.e., recommend having a separate line in the opposite arm for sample collection. 
k. Bone marrow aspirate: See Section 8.1 for details regarding bone marrow aspirates for disease assessment during the study. See Section 6.10 and Table 17 for details of the schedule for bone 
marrow assessments. If a baseline bone marrow sample could not be collected, an archival bone marrow sample (if available) should also be provided. In addition, a peripheral blood sample should 
be collected during screening and submitted for translational or biomarker research. If a peripheral blood sample was submitted during screening, on-study peripheral blood samples should also be 
collected for translational or biomarker research at the time of on-study bone marrow collection (Table 17). 
l. SL-172154 administration: Subjects will be monitored prior to, during, and for at least 4 hours after the completion of each SL-172154 infusion. Monitoring time may be shortened to 2 or 1 hour in 
later cycles. See Section 5.1.4 for details. SL-172154 should be administered according to the prescribed dosing schedule in Cycle 1 to align with the safety DLT assessment and sample (PK, ADA, 
etc.) collection schedules. Beginning on Cycle 1 Day 9, a window of ± 2 days is allowed for scheduled dosing days for drug administration (NOTE: each dose must be administered at least 5 days 
apart from the previous dose. If the start of a subsequent cycle (e.g., Day 2) is delayed, the current cycle length is extended (e.g., the cycle lasts longer than 28 days). On days when both SL-172154 
and azacitidine study drugs are administered, azacitidine administration should be completed at least 30 minutes prior to the start of the SL-172154 infusion.  
m. AE Monitoring: After signing of informed consent, but prior to initiation of study medications, only AEs (both serious or nonserious) caused by a protocol-mandated procedure will be collected (e.g., 
AEs related to invasive procedures such as biopsies). Subjects will be followed continuously for AEs during the study and for 30 days after the last dose of study medications (SL-172154 and/or 
azacitidine). After a subject is discontinued from SL-172154 or study therapy due to progressive disease or for other reasons, any ongoing AE should be followed until resolution (or return to baseline) 
and documented in the eCRF. If another anti-cancer agent is started within 30 days after the last dose of SL-172154, only SAEs and AEs that occur prior to the start of the new anticancer therapy 
should be recorded. In the event of a continuing SAE, the subject will be asked to return for follow-up until the SAE has resolved or is deemed to be continuing indefinitely. AEs will be characterized 
per NCI-CTCAE criteria v5.0 and events recorded in the eCRF.  

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Abbreviations: ADA = anti-drug antibody; aPTT = activated partial thromboplastin time; C = cycle; D = day; ECHO = echocardiogram; ECG = electrocardiogram; ECOG = Eastern Cooperative Oncology Group; FCBP = 
females of childbearing potential; INR = international normalized ratio; HBV = hepatitis B virus; HCV = hepatitis C virus; IV = intravenous; MDS = myelodysplastic syndrome; MUGA = multigated acquisition; PO = oral 
administration; PT = prothrombin time; PTV = Post Treatment Visit; SCRN = screening visit; SFU = Survival Follow-up; SQ = subcutaneous administration; TSH = thyroid stimulating hormone; q = every 
a)
Assessment Window:
-week intervals will have a ± 3-day window and 
assessments performed at > 4-week intervals will have a ± 1-week window. Laboratory tests can be performed up to 3 days prior to the scheduled dose. 
1) 
Day 8 assessments can be performed within ±3 days 
b) 
Screening: Screening Period extends from Day -21 to Day -1 for routine clinical assessments unless otherwise specified; subjects may complete Screening and initiate dosing on the same day 
provided all Screening assessments are completed and confirmed to meet eligibility requirements prior to receipt of the study drug. The following screening assessments do not need to be 
repeated on Cycle 1 Day 1 if performed within 72 hours of the first dose of study treatment: hematology, clinical chemistry, ECOG status, and physical exam.  
c) 
Post Treatment visit (PTV): visit should occur 30 days (± 7 days) from the last dose of study treatment. In addition to the assessments to be performed at the Post Treatment Visit, additional 
information, if available, should be collected regarding the subject. Beginning at the Post Treatment Visit and during Survival Follow-up, initiation of any subsequent anti-cancer therapy should 
also be reported. For subjects who proceed to HCT, HCT-relevant information should also be collected and entered in the eCRF. Should the subject be followed by another physician, the study 
Investigator should contact the subject’s hematologist/oncologist/transplant physician to obtain this information. See Section 6.13 for details. 
d) 
Eligibility evaluation: Subjects must meet all eligibility criteria prior to first dose of study drug. 
e) 
Hematology/Clinical Chemistry/Coagulation/Thyroid Function (TSH, free T4)/Antiviral Testing: will be performed at local laboratories according to the laboratory’s normal procedures. See 
Section 6.6.7 for list of laboratory tests required.  
1) Hematology should be performed on Day 15 of Cycles 1 through 4. If hematology assessment is performed on Day 15 of Cycle 5 or later, please provide the results.  
f) 
Cardiac Assessments: 12-lead electrocardiogram (ECG) and an echocardiogram (ECHO) or multigated acquisition (MUGA) scan must be performed at screening to serve as a baseline for 
comparison in the event of a cardiac AE/SAE. ECHO/MUGA scan or ECG performed within 30 days of first dose in this study does not need to be repeated during Screening. 
g) 
Vital Signs and Pulse Oximetry: Blood pressure (BP), heart rate (HR), temperature (T) and respiratory rate (RR) must be measured after the subject has been at rest (a semi-supine or sitting 
position) for at least 5 minutes (min). Collect vital signs/pulse oximetry predose (approximately 30 min of administration of azacitidine). 
h) 
Pregnancy Test: A serum pregnancy test (beta-
-hCG]) or urine pregnancy test must be performed at screening for all FCBP within 72 hrs of first dose of any 
study drug on Cycle 1 Day 1. FCBP must start using a highly effective method of contraception (i.e., <1% failure rate) at least 14 days prior to initiation of azacitidine and continue use during 
treatment and for the duration required by local prescribing information after the last dose of azacitidine (i.e., for sites in UK, at least 6 months after the last dose of azacitidine).  
1) Repeat this test every 8 weeks during azacitidine treatment (i.e., C3D1, C5D1, C7D1, etc. for every 8 weeks). 
i) 
Immunophenotying/Cytokines/Complement Analysis: Blood sample collection timing for immunophenotying, cytokine assessments and complement analysis are outlined in Section 6.4.1 in 
Supplementary Table 14. Blood volumes will be provided in the SLM. Cytokines samples should not be collected from infusion port for drug delivery i.e., recommend having a separate line in 
the opposite arm for sample collection. 
j) 
Bone marrow aspirate: See Section 8.1 for details regarding bone marrow aspirates for disease assessment during the study. See Section 6.10 for details of the schedule for bone marrow 
assessments for azacitidine. If a baseline bone marrow sample could not be collected, an archival bone marrow sample (if available) should also be provided. In addition, a peripheral blood 
sample should be collected during screening and submitted for translational or biomarker research. If a peripheral blood sample was submitted during screening, on-study peripheral blood 
samples should also be collected for translational or biomarker research at the time of on-study bone marrow collection Table 17. 
1) 
Bone marrow assessment is performed on C3D1 only. 
k) 
AE Monitoring: After signing of informed consent, but prior to initiation of study medications, only AEs (both serious or nonserious) caused by a protocol-mandated procedure will be collected 
(e.g., AEs related to invasive procedures such as biopsies). Subjects will be followed continuously for AEs during the study and for 30 days after the last dose of azacitidine. After a subject is 
discontinued from azacitidine due to progressive disease or for other reasons, any ongoing AE should be followed until resolution (or return to baseline) and documented in the eCRF. If another 
anti-cancer agent is started within 30 days after the last dose of SL-172154, only SAEs and AEs that occur prior to the start of the new anticancer therapy should be recorded. In the event of a 
continuing SAE, the subject will be asked to return for follow-up until the SAE has resolved or is deemed to be continuing indefinitely. AEs will be characterized per NCI-CTCAE criteria v5.0 and 
events recorded in the eCRF.  
l) 
Survival Follow-Up (SFU): All subjects will be contacted after discontinuing study therapy to collect survival status. Subjects should be contacted every 3 months (± 14 days) until death, 
withdrawal of consent, lost to follow-up or end of study. Contact may include clinic visit, telephone contact, email or mail to document survival status. Initiation of any subsequent anti-cancer 

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therapy should also be reported. For subjects who proceed to HCT, HCT-relevant information should also be collected and entered in the eCRF. Should the subject be followed by another 
physician, the study Investigator should contact the subject’s hematologist/oncologist/transplant physician to obtain this information. See Section 6.13 for details.
m)
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Results of TP53 gene mutation/deletion based on local evaluation must be available prior to 
randomization in Part D of the dose expansion cohort. 
6.5.7
Randomization
Following review of eligibility by the Investigator and Sponsor, sites will obtain a unique 
randomization number from the Randomization and Trial Supply Management (RTSM) system. 
Any completed randomization will be treated as an irreversible event and all randomized subjects 
will be included in study analyses and reports. Randomization codes cannot be reused once 
assigned via the study randomization system. 
6.6
Safety Evaluations 
6.6.1
Physical Examination
A complete physical examination should be performed by a qualified physician or their designee
per the schedule described in Section 6. The exam should include, at a minimum, assessments of 
the head and neck, eyes, ears, nose throat, skin, thyroid, cardiovascular, respiratory, 
gastrointestinal and neurological systems, lymph nodes and extremities. Height (at screening) and 
weight will also be measured and recorded. Investigators should pay special attention to clinical 
signs related to previous serious illnesses. Physical exams should be performed per standard of 
care during the on-treatment period.
6.6.2
ECOG Performance Status
Participant’s performance status will be assessed using the ECOG performance status tool 
(Section 16.8).
6.6.3 Pulse Oximetry 
Oxygen saturation will be measured with a pulse oximeter at room air without supplementation. 
Refer to SOA tables for details on when to collect pulse oximetry (Section 6). 
6.6.4 Vital Signs 
Vital signs should be assessed in a semi-supine or sitting position at rest and will include 
temperature (T), systolic and diastolic blood pressure (BP), heart rate (HR), and respiratory rate 
(RR). BP and RR measurements should be preceded by at least 5 min of rest for the participant in 
a quiet setting without distractions. Refer the SOA tables for details on when to collect vital signs 
(Section 6). 
6.6.5 Electrocardiogram 
A single, screening 12-lead ECG will be obtained as outlined in the SOA using an onsite standard 
of care ECG machine that automatically calculates HR and measures PR, QRS, QT, and corrected 
QT (QTc) intervals. ECGs should be performed as clinically indicated during the conduct of the 
study. Any treatment emergent abnormalities of clinical consequence should be reported as AEs. 
6.6.6 Echocardiogram/Multigated Acquisition (MUGA) scans 
A screening ECHO or MUGA scan will be obtained as outlined in the SOA to assess left 
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during the conduct of the study. Any treatment emergent abnormalities of clinical consequence 
should be reported as AEs. 
6.6.7
Local and Central Laboratory Assessments
Refer to the SOA in Section 6 for the timing and frequency of local laboratory tests performed. 
For subjects receiving venetoclax, the following additional laboratory assessments should be 
performed:
Blood samples for serum chemistry tests to monitor for TLS should be drawn (calcium, 
inorganic phosphorus, potassium, uric acid and creatinine) on the first, second and third 
day of venetoclax dosing at predose (within 4 hours prior to dosing) and 6 – 8 hours post-
dose during ramp-up, and 24 hours after reaching final dose. If the modified venetoclax 
ramp-up is used with strong CYP3A inhibitors (Section 16.7), samples should be drawn on 
the fourth day of venetoclax dosing.
International normalized ratio (INR) should be monitored more frequently in subjects using 
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Refer to the SOA in Section 6 for the timing and frequency of central laboratory tests performed 
on peripheral blood samples. A separate SLM detailing the preparation, storage, and shipping 
requirements for these samples collected during the study will be provided. 
Central Laboratory Tests on Peripheral Blood Samplesa 
Pharmacokinetics
SL-172154 serum concentration 
Immunogenicity
Anti-drug antibodies (ADA) to SL-172154
Protein analysis (serum)
Assessment of potential immune regulators such 
as cytokines/chemokines and complement 
activation proteins 
Receptor occupancy  
Flow cytometry-based measurement for receptor 
occupancy of SL-172154 on CD47 and CD40 in 
select subsets of peripheral blood mononuclear 
cells 
a. Samples in this table will be analyzed at a Central Lab. Refer to the SLM for details for sample collection procedures, handling, 
storage, and shipment instructions. 
Refer to the SOA in Section 6 for the timing and frequency of central laboratory tests performed 
on peripheral blood and bone marrow aspirates. A separate SLM detailing the preparation, storage, 
and shipping requirements for these samples collected during the study will be provided.
Central Laboratory Tests on Bone Marrow Aspiratesa 
Minimal Residual Disease (MRD) Assessment
(exploratory research)
Monitor MRD in subjects that attain CR/CRi/MLFS 
by multiparametric flow cytometry and/or NGS 
Immune Profiling
Lymphoid and myeloid subsets will be evaluated 
for activation and function
Evidence of SL-172154 localization on 
hematopoietic cells and/or malignant cells in the 
bone marrow by multiparametric flow cytometry
Receptor Occupancy (except in Part D) 
Flow cytometry-based measurement for receptor 
occupancy of SL-172154 on CD47 and CD40 
expressing cells in bone marrow mononuclear cells 
a.
Samples in this table will be analyzed at a Central Lab. Refer to the SLM for details for sample collection procedures, 
handling, storage and shipment instructions.

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6.6.7.1 
Ad Hoc Labs for IRR or CRS AEs
Ad hoc labs should be collected as noted if IRR or CRS events occur. 
Ad Hoc Labsa,b
Local Clinical Labs 
Central Labs
Complete blood count with differential
Chemistry Panel
D-Dimer
Coagulation panel
C-Reactive Protein
Ferritin 
Pharmacokinetics (SL-172154 serum 
concentration) 
Anti-drug antibodies
Cytokines and Chemokines 
All protocol-required central laboratory assessments must be conducted in accordance with the SLM.
a. 
Refer to the SLM for sample collection procedures, handling, storage and shipment instructions. PK will be measured with 
each corresponding ADA sample. 
b.
Specific biomarker, PK, ADA, and local clinical samples should be collected as soon as possible if an event of CRS or IRR 
occurs. 
6.6.7.2 
Pregnancy Testing
All FCBP subjects must have a negative pregnancy test (serum or urine) at Screening. A separate 
assessment is required if a negative Screening pregnancy test is obtained more than 72 hours before 
the first dose of SL-172154. Subjects with a positive pregnancy test must be excluded from the 
study. Subjects with a negative pregnancy test result must agree to use an effective contraception 
method as described in Section 16.3. 
6.6.7.3 
Blood Type and Screen (ABO/Rh) and DAT (except in Part D)
SL-172154 does bind RBCs but has not been shown to cause hemolysis in NHPs. However, 
treatment with SL-172154 may make phenotyping difficult due to expected coating of the RBC 
membrane. Thus, blood phenotyping, type and screen (ABO/Rh), and DAT should be performed 
at screening before exposure to SL-172154. At screening, the following testing should be 
performed: 1) ABO and D group (ABO/Rh) type and antibody screen and antibody identification 
if required; 2) DAT; 3) phenotype/genotype for, at a minimum, the minor antigens Rh C/c E/e, K, 
Jk, Fy and MNSs. If the subject has had transfusion within 21 days of C1D1 (e.g., Screening 
period) and the type/screen/DAT information is known, this information can be reported in the 
eCRF as baseline and the assessment does not need to be repeated. However, if the requested
information is unknown to the Investigator/site staff, then the assessment is to be performed during 
the Screening period.
6.7
Pharmacokinetics
The sampling schedule for PK of SL-172154 was determined based on observed PK in the Phase 
1 trial of SL-172154 monotherapy administered to subjects with ovarian cancer. The sampling 
schedule for PK assessment of SL-172154 is outlined in the Tables in Section 6

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6.8
Anti-Drug Antibody and Neutralizing Antibody Assessment 
The presence of ADA for SL-172154 will be assessed in samples collected according to the SOA 
(Section 6). Blood samples will also be collected for ADA/neutralizing antibody assessment within 
45 to 90 days of last dose of study treatment. 
6.9 
Pharmacodynamic Assessments in Blood 
6.9.1 Cytokine and Chemokine Analysis 
Levels of serum cytokines or chemokines have been shown to increase following administration 
immune modulating therapies and some chemotherapy agents including azacitidine. The 
assessment of cytokines or chemokines production after administration of SL-172154 in 
combination with azacitidine or azacitidine monotherapy may provide context to AEs observed in 
subjects following administration of SL-172154 or azacitidine as monotherapy or SL-172154
administered in combination with azacitidine with or without venetoclax and may act as PD
markers of activity. Refer to Tables in Section 6 for the schedule of the sample collection for these 
analyses.
6.9.2
Complement activation Analysis
The infusion-related reactions associated with the administration of immunotherapies and certain 
cancer drugs have been shown to involve the activation of the complement system, in a process 
called Complement activation-related pseudoallergy (CARPA). The concentration of the 
complement activation proteins (C3a, C4a, C5a, sC5b-9) may provide context to AEs in subjects 
following administration of SL-172154 administered with azacitidine in combination. To 
ascertain that complement activation is due to SL-172154 only and not because of the 
combination with azacitidine, samples will be collected in the azacitidine monotherapy control 
arm albeit in the minimum time point.  Refer to Tables in 6 for the schedule of the sample 
collection for these analyses. 
6.9.3 Receptor Occupancy and Immunophenotype 
Receptor occupancy of SL-172154 on CD47 and CD40 in peripheral blood cells will be measured 
by multiparameter flow cytometry. This analysis will provide evidence that SL-172154 is engaging 
the expected targets on different cell subsets and allows receptor occupancy to be calculated and 
assessed across SL-172154 dosing groups. In addition, activation markers will be assessed on 
different immune cell subsets across all dose groups. Refer to Tables in Section 6 for the schedule 
of the sample collection for these analyses. 
6.10 
 Bone Marrow Assessments 
Bone marrow aspirates must be performed for all subjects for diagnostic evaluation (includes 
response assessment) and biomarker analysis (includes exploratory research) at designated 
timepoints throughout the study as outlined in Section 6 Any results for bone marrow aspirates 
performed in addition to those required per protocol should also be captured in the eCRF. Further 
details on sample collection, processing, and shipping procedures will be provided in the SLM.  
A portion of the aspirate must be processed according to the institutional standard procedures for 
diagnostic evaluation; however, a sample of the bone marrow aspirate should also be collected for 

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6.10.2 Bone Marrow Aspirate Sample (Central Laboratory) 
6.10.2.1 
Bone Marrow Aspirate for MRD Assessment by Flow Cytometry  
Multiparameter flow cytometry (MFC), for detecting leukemia-associated immunophenotypes 
(LAIPs) is the current standard method for MRD assessment. The CD markers in line with the 
consensus recommendations from European Leukemia Network AML working party [Schuurhuis, 
2018] will be selected for MFC. This is an exploratory analysis and would not be used to guide 
treatment decisions. 
6.10.2.2 
Bone Marrow Aspirate for Molecular Genetic Profiling 
Molecular profiling may be performed to assess genetic aberrations in the bone marrow aspirate 
collected at Screening and during disease assessment from subjects with AML or MDS. These 
molecular genetic markers may be the basis for MRD evaluation in subjects with AML who 
achieve CR/CRi/MLFS or subjects with MDS who achieve CR/marrow CR. In addition, a 
peripheral blood sample may also be collected at the same timepoints for similar molecular 
profiling of genetic aberrations. These are exploratory analyses and would not be used to guide 
treatment decisions.
6.10.2.3
Bone Marrow Aspirates for Receptor Occupancy Analyses (Dose 
Escalation and Dose Expansion cohorts; Parts A, B and C)
Receptor occupancy of SL-172154 on CD47 and CD40 on bone marrow cells will be measured by 
flow cytometry, using bone marrow aspirate specimens collected in the SL-172154 monotherapy 
cohorts, on Cycle 2 Day 1, Cycle 3 Day 1 (if a bone marrow aspirate is required), and 
Cycle 5 Day 1, and in the combination cohorts, on Cycle 2 Day 2, Cycle 3 Day 2 (if a bone marrow 
aspirate is required), and Cycle 5 Day 2.  
If this timepoint designated above is not feasible, make every effort to perform a bone marrow 
aspirate within 24 hours from the completion of a SL-172154 dose (as an example for SL-172154 
monotherapy, the bone marrow aspirate should be performed on Cycle 2 Day 2 within 24 hours 
after the SL-172154 dose was completed on Cycle 2 Day 1; as an example for the combination 
therapy, the bone marrow aspirate should be performed on Cycle 2 Day 3 within 24 hours after 
SL-172154 dose was completed on Cycle 2 Day 2). 
Alternatively, a bone marrow aspirate can be performed on the day of a prior dose (e.g.,
Cycle 1 Day 22 for monotherapy; Cycle 1 Day 23 for combination therapy) or on the day of a 
subsequent dose (e.g., Cycle 2 Day 8 for monotherapy; Cycle 2 Day 9 for combination therapy); 
in these cases, the bone marrow aspirate must be performed after completion of that day’s 
SL-172154 infusion.  
If this is still not feasible, make every effort to perform bone marrow aspirate within 24 hours from 
the completion of a SL-172154 dose (as an example for SL-172154 monotherapy, bone marrow 
aspirate should be performed on Cycle 1 Day 23 within 24 hours after SL-172154 dose was 
completed on Cycle 1 Day 22; as an example for the combination therapy, bone marrow aspirate 
should will be performed on Cycle 1 Day 24 within 24 hours after from the completion of when 
SL-172154 dose was completed on Cycle 1 Day 23). 

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6.10.2.4 
Bone Marrow Aspirate for Translational or Biomarker Research
Translational or biomarker research may be performed on bone marrow aspirates collected on-
study to better understand AML and MDS, and mechanism of action of and response to SL-172154 
(monotherapy or in combination regimen).  
These analyses include but are not limited to cytogenetics and molecular genetic testing, immune 
profiling, and MRD status assessment. Comparative examination of pre-dosing profiles of 
participants may uncover known or novel candidate biomarkers/profiles which could be used to 
predict response to treatment with SL-172154 or provide new insights into AML/MDS and 
medically related conditions. Comparative examination of post-dosing profiles in conjunction with 
pre-dosing profiles may yield known and novel candidate biomarkers/profiles and new insights 
which relate to the action of SL-172154. Performance of these investigations may be conditional 
on the results of the clinical trial principally, but not exclusively, on the primary measures of the 
clinical trial outcome, and samples may be selected for analysis on the basis of the clinical 
outcome. Unless stated otherwise, these investigations may be performed irrespective of whether 
a response to SL-172154 (monotherapy or in combination regimen) is observed.
6.11
Transformation to Acute Myeloid Leukemia (Only for MDS Subjects)
Transformation to AML will be monitored in subjects who enter the study with a diagnosis of 
MDS, and will be included as part of the safety assessment throughout the course of the study. 
Transformation to AML should be reported if documented at any time from signing of ICF through 
death, lost to follow-up, withdrawal of consent for further data collection, or study closure 
(whichever is later), whether or not it is thought to be related to treatment with study drugs. 
Documentation supporting the diagnosis of transformation to AML (e.g., confirmatory histology 
or cytology results) should be collected and documented on the appropriate eCRFs. MDS subjects 
with transformation to AML will discontinue study treatment on this trial and enter the follow-up 
part of the study; any subsequent anti-cancer therapy initiated for these subjects should be collected 
in the eCRF. 
6.12
Transfusion Assessment
The following should be recorded for all transfusions the subject received within 4 weeks (subjects 
with AML) or 8 weeks (subjects with MDS) prior to first dose of study treatment, during study 
treatment, and until 30 days after the last dose of study treatment or at the time of the Post
Treatment Visit, whichever occurs later:
 Type of blood product transfusion (e.g., RBC or platelets) 
 Number of units
 Reason for transfusion
 Date of transfusion
 Hemoglobin value for which each RBC transfusion is given 
 Platelet value for which each platelet transfusion is given
RBC transfusions administered for surgical procedures, significant hemorrhagic events, or other 
reasons documented as unrelated to disease-associated anemia will not be counted in the 
assessment of baseline transfusion burden, efficacy, or progressive disease status. 

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6.13
Information Collected at Post Treatment Visit and During Survival Follow-Up Period
In addition to the assessments noted in the Schedule of Assessment table (Section 6) to be 
performed at the Post Treatment Visit (PTV), additional information should be collected regarding 
the subject. Beginning at the PTV and during Survival Follow-up, the start date and agent name 
of subsequent anticancer therapy(ies) for AML or MDS will be collected and entered in the eCRF. 
The PTV should occur 30 days (±7 days) from the last dose of study treatment. If the PTV occurs
earlier than 30 days after the last dose of study treatment, safety information up to 30 days after 
the last dose of study treatment will be collected during Survival Follow-up. In addition, for 
subjects that proceed to HCT, HCT-relevant information (e.g., type of transplant, GVHD and 
transplant-related complications) may also be collected and entered in the eCRF. Should the 
subject be followed by another physician, the study Investigator should contact the subject’s 
hematologist/oncologist/transplant physician to obtain this information.
6.14
Unscheduled Visit
Additional visits can be performed as appropriate and at the discretion of the Investigator. 
Assessments completed during unscheduled visits will be captured in the eCRF. Clinical 
hematology and chemistry labs may be collected if considered necessary for subject assessment. 
All AEs or SAEs reported by the subject or observed by the Investigator should be documented 
and reported; this includes relevant medical information gathered during the unscheduled visit 
related to clinical assessment of AEs or SAEs (Section 7.4).
7.
SAFETY ASSESSMENTS
Safety surveillance reporting of adverse events (AEs) commences when a subject has signed the 
ICF, throughout the course of treatment, and up to 30 days after the last dose of investigational 
drug. After signing of informed consent, but prior to initiation of study medications, only AEs 
(both serious or nonserious) caused by a protocol-mandated procedure will be collected (e.g., AEs 
related to invasive procedures such as biopsies). All observed or volunteered AEs (serious or non-
serious) and abnormal laboratory test findings, if applicable, whether suspected to have a causal 
relationship to study treatment or not will be recorded in the subject medical record and in the 
eCRF. For all AEs, sufficient information will be pursued and/or obtained to permit an adequate 
determination of seriousness and outcome of the event (i.e., whether it should be classified as a 
SAE or not) and an assessment of the causal relationship between the AE and each of the study 
drugs (SL-172154, azacitidine, or venetoclax). All AEs (both serious and nonserious) will be 
followed in accordance with good medical practice until resolution, return to baseline, subject is 
lost to follow-up, the AE is otherwise explained, or it is deemed that further recovery is unlikely. 
Following the Post Treatment Visit, subjects with ongoing drug-related AEs and SAEs should be 
followed until resolution to baseline or stabilization of these events, unless the subject withdraws 
from the study or starts another anti-cancer treatment. Follow-up will stop when the subject begins 
another anti-cancer treatment. Refer to Section 7.4 for documentation and reporting of adverse 
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Event
Definition
with the underlying disease, unless judged by the Investigator to be more 
severe than expected for the participant’s condition.
All laboratory tests with clinically significant abnormal values during 
participation in the study should be repeated until the values return to 
normal or baseline or are no longer considered clinically significant by the 
Investigator. 
If such values do not return to normal/baseline within a period judged 
reasonable by the Investigator, the etiology should be identified, and the 
results must be recorded in the eCRF. 
If laboratory values from non-protocol specified laboratory assessments 
performed at the institution’s local laboratory require a change in subject 
management or are considered clinically significant by the Investigator 
(e.g., AE, SAE or dose interruption), then the results must be recorded in 
the eCRF 
Unexpected Adverse 
Reaction
An adverse reaction (causality related Adverse Event), the nature, severity 
or outcome of which is not consistent with the reference safety information 
section of the SL-172154 IB. Product reference safety information is 
contained in the current Guidance for Investigators in Section 6.0 of the 
Investigator’s Brochure provided to the Investigator by the Sponsor.
Suspected Unexpected 
Serious Adverse Reaction 
(SUSAR)
Suspected Adverse Reaction (causality related AE) that is serious and 
unexpected. 
7.1.1
Events Not Qualifying as AE or SAE
The following are not considered to be AEs or SAEs:
 Medical or surgical procedures (e.g., endoscopy, appendectomy). The condition that leads 
to the procedure is considered the AE.
 Elective procedures, planned hospitalizations, and procedures for treatment of conditions 
noted in the subject’s medical history (present prior to signing the ICF) that have not 
worsened are not considered AEs.  
 Situations where an untoward medical occurrence did not occur (i.e., admission to hospital 
for social circumstances). 
 Anticipated day-to-day fluctuations of pre-existing medical conditions that were present at 
start of study. These conditions are considered part of the subject’s medical history and 
must be adequately documented on the appropriate page of the CRF. 
 Clear progression of disease under study should not be reported as an AE or SAE (unless 
the Investigator considers the progression of underlying neoplasia to be atypical in its 
nature, presentation or severity from the normal course of the disease in a particular 
subject). Signs and symptoms that are clearly consistent with the expected progression of 
the underlying cancer should not be reported as an adverse event, and hospitalizations due 

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to the progression of cancer do not necessarily qualify for an SAE. Deaths that are clearly 
determined to be due to disease progression should not be reported as AEs/SAEs. 
In the case where the medical condition is known when the participant enters the trial, only 
worsening (increased frequency or intensity of the episodes or attacks) will be documented 
as an AE. If the medical condition is detected during the trial, and if repeated episodes 
enable diagnosis of a chronic disease, the episodes will be grouped together in the CRF, 
and the diagnosis will be clearly described. 
Laboratory abnormalities: An isolated, out-of-range laboratory result in the absence of any 
associated, clinical finding may or may not be considered an AE. The Investigator’s 
evaluation should be based on a consideration of the overall clinical context. 
7.1.2
Adverse Events Commonly Associated with AML or MDS Study Population and/or 
Progression of Disease
Certain AEs are anticipated to occur in the study population (AML or higher-risk MDS) at some 
frequency independent of drug exposure. These are discussed as AEs commonly associated with 
the disease or progression of disease. Such events include known consequences of the underlying 
disease under investigation (e.g., symptoms, disease progression).
Cytopenias (anemia, neutropenia, or thrombocytopenia) are part of the natural history of AML and 
MDS. Persistent cytopenias at the same CTCAE grade as at baseline are not to be reported as 
adverse events, unless they fulfill a seriousness criteria, result in permanent discontinuation of a 
study drug, or the Investigator had an identifiable cause other than the underlying disease. Any 
clinically relevant abnormal laboratory assessment between screening and prior to administration 
of the first dose of study treatment will be recorded in the subject’s medical history. 
7.2 
Classification of an Adverse Event 
All measures required for AE management and the ultimate outcome of the event will be recorded 
in the source document and reported to the Sponsor. 
7.2.1 Assessment of Severity 
The descriptions and grading scales found in the revised NCI-CTCAE version 5.0 will be utilized 
for AE reporting. A copy of these criteria can be downloaded from the website: 
https://ctep.cancer.gov/protocoldevelopment/electronic applications/ctc.htm. 
For AEs not included in the NCI-CTCAE v5.0 grading system, the following guidelines will be 
used to describe severity: 
 Grade 1: mild
 Grade 2: moderate 
 Grade 3: severe 
 Grade 4: life-threatening 
 Grade 5: death  
NOTE: A distinction should be drawn between serious and severe AEs. Severity is an estimate or 
measure of the intensity of an AE, while the criteria for serious AEs are indications of adverse 

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subject outcomes for regulatory reporting purposes. A severe AE need not necessarily be 
considered serious and a serious AE need not be considered severe.
7.2.2 Assessment of Causality 
The clinician’s assessment of an AE’s relationship to study treatment is part of the documentation 
process, but it is not a factor in determining what is or is not reported in the study. If there is any 
doubt as to whether a clinical observation is an AE, the event should be reported. All AEs must 
have their relationship to study treatment (SL-172154, azacitidine, or venetoclax) assessed. In a 
clinical trial, the IP must always be suspect. To help assess causality, the following guidelines are 
used. 
Related – There is reasonable causal relationship between the study drug and the AE. The 
event responds to interruption of study drug and recurs with re-challenge, when clinically 
feasible. 
Possibly Related – There is reasonable causal relationship between the study drug and the 
AE. Information on whether the event responds to interruption of study drug and/or re-
challenge is lacking or unclear. 
Unlikely Related – There is a temporal relationship to study drug administration, but there 
is not a reasonable causal relationship between the study drug and the AE (i.e., the AE is 
doubtfully related to study drug). 
 Not Related – There is not a temporal relationship to study drug administration (e.g., too 
early, too late, or study drug not taken), or there is a reasonable causal relationship between 
another drug, concurrent disease, or circumstance and the AE. 
7.2.3 Expectedness 
The Sponsor will be responsible for determining whether an AE is expected or unexpected. 
 Unexpected – An AE will be considered unexpected if the nature, severity, or frequency 
of the event is not consistent with the safety information in the Guidance for Investigators,
Section 6 of the current SL-172154 IB. “Unexpected,” as used in this definition, also refers 
to AEs or Ars that are mentioned in the IB as occurring with a class of drugs or as 
anticipated from the pharmacological properties of the drug not specifically mentioned as 
occurring with the IP under investigation.  
 Expected – AEs that are common and known to occur for the IP being studied. 
Expectedness refers to the awareness of AEs previously observed, not on what might be 
anticipated from the properties of the IP.
7.3
Timing for Event Assessment and Follow-Up
All AEs occurring while on-study must be documented appropriately regardless of relationship. 
All AEs will be followed to adequate resolution. The occurrence of an AE or SAE may come to 
the attention of study personnel during study visits and interviews of a study subject presenting for 
medical care, or upon review of source documents by a study monitor. 
Any medical condition that is present at the time that the subject is screened will be considered as 
baseline (e.g., medical history) and not reported as an AE.  

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7.4
Procedures for Recording and Reporting of Adverse Events 
Event
Reporting Procedure
Adverse Event
Subjects will be followed continuously for AEs during the study and for 30 days 
after the last dose of IP. After a subject is discontinued from IP due to 
progressive disease or for other reasons, any ongoing AE should be followed 
until resolution (or return to baseline) and documented in the eCRF, regardless 
of whether the event(s) is attributed to trial medication. If another anti-cancer 
agent is started within 30 days of the last dose of SL-172154, only SAEs and 
AEs that occur before the new anticancer therapy should be recorded. The 
following information will be recorded: description, date of onset and end date, 
severity, assessment of relatedness to trial medication, and action taken. Follow-
up information should be provided, as necessary. AEs will be followed either 
until resolution, or the event is considered stable. 
It will be left to the Investigator’s clinical judgment to decide if an AE is of 
sufficient severity to require the subject’s removal from treatment. A subject may 
also voluntarily withdraw from treatment due to what he or she perceives as an 
intolerable AE. If either of these occurs, the subject must undergo an end of 
treatment assessment and be given appropriate care under medical supervision 
until symptoms cease, or the condition becomes stable. 
Serious Adverse Event
An SAE Form should be completed within the following timelines: 
 All deaths and immediately life-threatening events meeting the SAE 
criteria (as outlined in Section 7.1), whether related or unrelated, will be 
recorded on the SAE Form and submitted to the study Sponsor or 
designee within 24 hours of site awareness.  
 Other SAEs regardless of relationship, will be submitted to the study 
Sponsor or designee within 24 hours of site awareness.  
All SAEs will be followed until satisfactory resolution or until the site Investigator 
deems the event to be chronic or the adherence to be stable. Other supporting 
documentation of the event may be requested by the Sponsor and should be 
provided as soon as possible. The Sponsor will be responsible for notifying 
Regulatory Authorities of any unexpected fatal or life-threatening suspected 
adverse reaction (AR) as soon as possible but in no case later than 7 calendar 
days after the Sponsor’s initial receipt of the information. The Sponsor will be 
responsible for notifying Regulatory Authorities of any other serious unexpected 
suspected adverse reaction as soon as possible but in no case later than 15 
calendar days after the Sponsor’s initial receipt of the information.
 
Sponsor Contact Information for SAE Reporting 
 
Email: 
eFax number: 
 

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7.5
Reporting of Pregnancy 
Although not an AE in and of itself, pregnancy as well as its outcome must be documented via the 
Pregnancy Report Form provided by the Sponsor. Any pregnancy occurring in a participant or 
participant’s partner from the time of consent to 30 days after the last dose of IP must be reported 
and then followed for outcome. Newborn infants born to the subject or subject’s partner should be 
followed until 30 days old. 
A FCBP must discontinue study treatment immediately if they become pregnant during the study. 
To ensure subject safety, each pregnancy must be reported to the Sponsor within two weeks of 
learning of its occurrence. The pregnancy must be followed to determine outcome (including 
premature termination) and status of mother and child. Pregnancy complications and elective 
terminations for medical reasons must be reported as an SAE. Spontaneous abortions must be 
reported as an SAE.
Any SAE occurring in association with a pregnancy brought to the Investigator’s attention after 
the subject has discontinued study treatment must be promptly reported to the Sponsor.
7.6
Reporting of Overdose, Misuse of IP, or Suspected Transmission of Infectious Agent
The following events should also be reported to the Sponsor within 24 hours of knowledge of the 
event:
An overdose of SL-172154 
Suspected transmission of an infectious agent due to contamination of drug product
Other events related to misuse of IP
7.7
Study Halting Rules
Administration of IP will be halted if a fatal SAE related to SL-172154 is reported to the Sponsor. 
The Sponsor will inform the Investigators immediately if such an event is reported. Screening and 
new study enrollment will be stopped. The Sponsor will convene an ad hoc meeting of the SMC 
to review the SAE and overall safety profile and provide recommendations. The study Sponsor 
will inform the regulatory authorities (i.e., FDA, European Medicines Agency, etc.) of the 
temporary halt and the disposition of the study.
7.8
Safety Oversight
An SMC will be implemented in this study and will consist of Investigators and Sponsor 
representatives. SMC meetings will be conducted monthly (or more frequently if required) during 
dose escalation and approximately every 2 months during dose expansion to review and discuss 
safety data and communicate results of ongoing analyses during dose escalation and dose 
expansion provided subjects have been enrolled and data are available to be reviewed. The SMC 
will operate in accordance with the SMC charter which will define roles and accountabilities and 
the process for safety review. Throughout the conduct of the study, safety data will be reviewed 
by the Sponsor for each subject on an ongoing basis. Additionally, periodic safety reviews will be 
undertaken by the SMC as defined in the SMC charter. As dose escalation proceeds, the SMC will 
consider data from Study SL03-OHD-104 as well as other knowledge obtained for SL-172154, 
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Safety and pharmacokinetic data from Study SL03-OHD-101 will be shared with the SMC for 
SL03-OHD-104. All dose escalation or safety decisions made by the SMC will be documented in 
writing with copies maintained at each site and the Trial Master File at the Contract Research 
Organization. Based on the severity of the DLTs, indicators of potential anti-tumor activity, and 
other factors, a recommendation on whether to modify the dose and/or study design or continue 
enrollment will be made by the Sponsor collaboratively with input from the SMC. Regulatory 
authorities and IRBs/IECs will be notified of any decisions to prematurely halt the study or subject 
enrollment. See Section 14.1 for details on safety meetings. 
8.
EFFICACY ASSESSMENTS
Disease evaluations will include bone marrow examinations, MRD assessment, hematologic 
parameters (e.g., hemoglobin, ANC, platelet counts), and physical examination of extramedullary 
disease of AML. Survival status will also be collected. 
All efficacy assessments must be performed until relapse/progression, discontinuation of study 
treatment for a subsequent HCT, or withdrawal of consent, even if the subject is discontinued from 
study therapy. If a subject discontinues study treatment for reasons other than relapse/progression, 
disease assessments should continue until disease relapse/progression or the initiation of a 
subsequent AML or MDS anti-cancer therapy. Disease assessment will be performed as outlined 
in the Schedule of Assessments (Section 6).
8.1
Bone Marrow Aspirate for Disease Assessment
Bone marrow aspirates must be performed at screening for all subjects. The bone marrow aspirate 
during screening should be performed after all other eligibility criteria have been met. Refer to 
Section 6.1 and Section 6.2 for the schedule of additional bone marrow aspirates obtained during 
the study.  
A sufficient bone marrow aspirate must be collected for clinical disease assessment and biomarker 
assessments. Bone marrow aspirate samples must be collected for all subjects. If a bone marrow 
aspirate sample is not evaluable, another aspirate sample should be performed within 7 days. Any 
results for bone marrow assessments performed as standard of care throughout the study should 
also be captured in the eCRF. A portion of bone marrow aspirate performed for disease assessment 
at selected timepoints (see Section 6.10) will be sent to a central lab for exploratory research 
outcome measures.  
8.1.1 AML Response Criteria 
Response will be evaluated based on guidelines by the 2017 ELN Response Criteria in AML
[Dohner, 2017]. Subject’s response is based on the most recent bone marrow results and recent 
hematology values. Hematology values for up to 2 weeks from the bone marrow evaluation can 
be used to determine the response. As a significant number of subjects in this study might have 
antecedent hematologic illness, hematologic response including transfusion independence will 
also be evaluated.  
All subjects who completed at least one cycle of study treatment will be assessed by the 
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And any of the following:
At least 50% decrement from maximum remission/response in granulocytes or 
platelets
 Transfusion dependence
Response assessment for HI will be performed at each cycle beginning in Cycle 2 regardless of 
whether a bone marrow test is performed. HI will be assessed according to the IWG 2006 MDS 
criteria. Responses must last at least 8 weeks. The transfusion policy for the individual subject 
prior to therapy should be maintained on treatment if not otherwise clinically indicated. A
maximum variation between pre- and on-study practice of 1 g/dL (or 0.6 mmol/L) in terms of 
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subjects, the posterior unit probability for subintervals will be calculated based on a 
noninformative prior distribution for the DLT rate (Beta (1,1)) and the total number of subjects 
with DLTs and DLT-evaluable subjects for the current dose. A dose escalation/stay/de-escalation 
decision that corresponds to the subinterval with the highest unit probability mass will be selected. 
A minimum of 3 DLT-evaluable subjects will be enrolled to a dose level and evaluated for DLT 
before a dose escalation/stay/de-escalation decision can be made unless unacceptable toxicity is 
observed prior to the enrollment of 3 subjects e.g., two subjects experience DLT before the third
subject enrolls. A dose level will be considered unsafe, with unacceptable toxicity and no 
additional subjects enrolled at that dose level and above, if it has an estimated 95% or more 
probability of exceeding the target DLT rate of 20%. The maximum number of subjects evaluated 
for DLT for each dose level will be 15 subjects (about 3 cohorts of 5 subjects) if the dose escalation 
decision is to stay at the current dose from the first 2 cohorts. Based on the above design, the dose 
escalation decision rules for each dose level are:
Dose escalate if the observed DLT rate <14%;
Stay at the current dose if the observed DLT rate between 14%-24%;
Dose de-escalate if the observed DLT rate 25%
See Table 18 for dose escalation decision rules based on the total number of subjects evaluable for 
DLT and the number of subjects with DLT observed. The operating characteristics of the mTPI-2 
design based on 10,000 simulations are in Table 19. 

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Table 19 
Operating Characteristics of mTPI-2 Design Based on 10000 Simulations
Dose 1
Dose 2
Dose 3
Dose 4
Dose 5
Number of 
Patients 
% Early 
Stopping 
Scenario1
 
True DLT rate 
0.2
0.35
0.43 
0.48 
0.54 
Selection % 
76.32 
12.23
0.96 
0.13 
0
10.36
# Pts treated
14
5.57
0.65
0.04
0
20.3
Scenario2
 
True DLT rate 
0.07 
0.2
0.35 
0.46 
0.57 
Selection % 
23.78 
59.72
15.07
1.07 
0.03 
0.33
# Pts treated
10.34 
12.19
4.38 
0.44 
0.01 
27.4 
Scenario3
 
True DLT rate
0.01
0.04
0.08
0.2
0.35
Selection % 
0.08 
2.48
31.41
53.52
12.51
0
# Pts treated
5.36 
6.56
8.55 
7.34 
2.01 
29.8 
Scenario4
 
True DLT rate 
0.05 
0.1
0.2
0.4
0.55 
Selection % 
4.2
29.52
56.36
9.54 
0.26 
0.12
# Pts treated
7.18 
9.95
8.94 
2.6
0.13 
28.8 
9.1.2
Dose Expansion
For Part A dose expansion cohort, the goal is to enroll approximately 20 previously untreated HR-
MDS subjects treated at the potential RP2D in dose escalation and dose expansion.  For Part B
dose expansion cohort, the goal is to enroll approximately 20 previously untreated AML subjects 
treated at the potential RP2D in dose expansion or safety run-in. For the Part C dose expansion 
cohort, the goal is to enroll approximately 20 subjects with TP53 mutated or deleted AML treated 
at the potential RP2D of SL-172154 and azacitidine in dose expansion. The sample size of 20 is
primarily chosen to obtain a preliminary assessment of the anti-tumor activity with a certain degree 
of precision. Table 20 provides the 90% confidence interval (CI) based on exact probability 
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Table 20 
Response Rate and 90% CI Out of 20 Subjects 
# Responses / 20 
Subjects
Response rate
90% CI 
2 
10%
1.8%, 28.3% 
4
20%
7.1%, 40.1%
6
30%
14.0%, 50.8%
8
40%
21.7%, 60.6%
10
50%
30.2%, 69.8%
12
60%
39.4%, 78.3%
14
70%
49.2%, 86.0%
16
80%
59.9%, 92.9%
18
90%
71.7%, 98.2%
For the Part D dose expansion cohort, 60 previously untreated subjects with higher-risk 
(intermediate, high, or very high per IPSS-R) MDS will be randomized 1:1:1 to three arms: 3.0 
mg/kg of SL-172154 in combination with azacitidine (n=20), 1.0 mg/kg of SL-172154 in 
combination with azacitidine (n=20), or azacitidine monotherapy (n=20). Subjects will be 
similar distribution for these 2 stratification factors across treatment arms. The sample size 
calculation was performed using nQuery version 9.3.1. A sample size of 20 in each arm provides 
71% power to detect difference in CR rate between SL-172154 in combination with azacitidine 
(either 3mg/kg or 1mg/kg) and azacitidine monotherapy based on the following assumptions:
CR is 22% for azacitidine monotherapy
CR rate is 55% for SL-172154 in combination with azacitidine (either SL-172154 3.0
mg/kg or 1.0 mg/kg)
One-sided type one error is 0.1
Each dose expansion cohort will allow further characterization of the safety profile of SL-172154 
in combination with azacitidine or azacitidine and venetoclax, with particular emphasis on 
toxicities leading to discontinuation of SL-172154 and the combination agents, SAEs and 
Grade
. The SMC will meet monthly during dose escalation, provided that subjects have 
been enrolled and data are available, to review and discuss safety data and communicate results of 
ongoing analyses throughout the conduct of dose expansion. Continuous toxicity monitoring based 
on the Pocock-type stopping boundary [Ivanova, 2005] will be used for the rate of AEs leading to 
treatment discontinuation (e.g., prolonged neutropenia lasting past cycle day 42 in the absence of 
AML or MDS, high-grade non-hematologic adverse events, treatment-related deaths) within the 
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When determining the RP2D, the totality of the safety, tolerability, PK, PD and efficacy data is 
taken into consideration. 
9.2.1
Analysis Populations
The populations defined for analysis will include the following:
Enrolled population: all subjects who have signed the main study informed consent. 
Screen failures: all subjects who have signed the main study informed consent but have not 
received any dose of study treatment.
 All Treated Population: all subjects who receive at least one dose of any study drug(s). 
Safety data will be evaluated based on this population.  
 Intent-to-treat (ITT) population for Part D cohort of dose expansion: all randomized 
subjects regardless of whether or not treatment was administered. This population will be 
based on the treatment to which the subject was randomized. Any subject who receives a 
treatment randomization number will be considered to have been randomized.  
 DLT-Evaluable Population: all subjects enrolled in the dose escalation cohorts (SL-172154
monotherapy, or SL-172154 and azacitidine combination) or in the safety run-in cohort 
(SL-172154, azacitidine and venetoclax) who receive at least 2 of 4 scheduled doses of 
SL-172154 and at least 50% of the scheduled doses of the combination agent (azacitidine 
or venetoclax) and complete the safety follow-up through the DLT evaluation period or 
experience any DLT during the DLT evaluation period. DLT-evaluable subjects will be 
used to guide dose escalation and to determine the MTD or MAD. 
 Pharmacokinetic Population: subjects in the All Treated Population from whom at least 
one PK sample is obtained and analyzed. 
 Response-Evaluable Population: subjects in the All Treated Population who have at least 
one post-baseline disease assessment or who have progressed or died before the first post-
baseline disease assessment.  
 ADA Analysis Population: subjects in the All Treated Population for whom at least one 
ADA sample is obtained and analyzed.
 Pharmacodynamic Population: subjects in the All Treated Population for whom at least 
one PD sample is obtained and analyzed.
9.2.2
Data Analysis During Dose Escalation and Safety Run-In 
During the dose escalation and safety run-in, the number of subjects with DLTs will be determined 
after each cohort of approximately 5 subjects has been evaluated for DLT. The summary of DLTs 
will be based on the DLT-evaluable population; the number of subjects with DLTs will be 
summarized by dose level. Selected AE summary tables and listings may be provided during dose 
escalation to support dose escalation decisions.  

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9.2.3
General Data Analysis and Consideration
Tabular summaries will be presented by dose levels/cohorts and total number of subjects in the 
corresponding population. Categorical data will be summarized by the number and percentage of 
subjects in each category. Continuous variables will be summarized by descriptive statistics.  
As it is anticipated that accrual will be spread across centers and summaries of data by center 
would be unlikely to provide valuable information, data from all participating centers will be 
pooled prior to analysis. All data up to the time of study completion/withdrawal from study will 
be included in the analysis for each subject, regardless of duration of treatment. 
9.2.4 Safety Analyses 
The safety evaluation will be based on the All Treated Population and the DLT evaluation will be 
based on the DLT-evaluable population.
DLTs will be summarized by dose level/regimen for combination dose escalation cohorts and by 
dose level for the monotherapy cohort. Frequency tables by dose levels will be used to describe 
safety and tolerability parameters such as: AEs, SAEs, fatal AEs AEs leading to dose reduction of 
SL-172154, and AEs leading to discontinuation of SL-172154, azacitidine and venetoclax. 
Changes in toxicity grade for safety assessments (e.g., laboratory parameters, etc.) will also be 
summarized. Figures may also be presented where appropriate. AEs will be mapped to a Medical 
Dictionary for Regulatory Activities (MedDRA) preferred term and system organ classification. 
AEs will be graded according to the NCI CTCTAE v5.0. CRS will be graded per the ASTCT 
Consensus Grading Criteria for CRS. Concomitant medications will be coded using the WHO
Drug Dictionary.  
Maximum Tolerated Dose:  
The MTD will be estimated using isotonic regression (based on the DLTs observed in DLT-
evaluable subjects). Specifically, the MTD is the dose for which the isotonic estimate of the DLT 
rate is closest to the target DLT rate of 20% among all dose with the isotonic estimate of DLT rate 
15%. If two or more doses tie for the smallest difference, the following rules will be performed:
If the estimated DLT rate < 20% for all doses, then select the higher dose among the tied 
doses;
If the estimated DLT rate for the tied doses are a combination of < 20% and > 20% for all 
doses, then select the higher dose among the tied doses;
If the estimated DLT rate > 20% for all doses, then select the lower dose among the tied 
doses;
An MAD will be reported if the isotonic estimate of DLT rate is less than 15% for all dose levels. 
Otherwise, an MTD will be reported. 
9.2.5
Efficacy Analyses
For dose escalation and Parts A, B and C of dose expansion, efficacy analysis will be based on the 
All Treated population and Response-Evaluable populations. All efficacy data will be summarized 
by treatment regimen, dose level, prior treatment status (treatment naïve or relapsed/refractory 

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disease), TP53 mutation or deletion (Yes or No for subjects with AML), and overall for MDS and 
AML, respectively.  
For Part D of dose expansion, efficacy analysis will be based on the ITT, All Treated and response 
evaluable population. All efficacy data will be summarized by the treatment arm. The CR rate and 
95% CI in each arm will be calculated and CR rate will be compared between SL-172154 1 mg/kg 
or 3mg/kg in combination with azacitidine and azacitidine monotherapy using Fisher’s exact test, 
95% CIs for the difference in CR rate will be calculated. If data warrant, the CR rate will be 
compared using Cochran-Mantel-Haenzszel (CMH) test stratified by stratification factors used in 
randomization.  There is no adjustment for multiple comparisons. The primary efficacy analysis 
will include the following outcome measures: 
 CR is defined as the proportion of subjects who reach CR prior to the initiation of any new 
therapy for AML or MDS.  
Duration of CR is measured from the date when the CR criteria are first met to the date of 
relapse or death, whichever occurs first. 
 Time to CR is defined as the time from the first dose of study treatment to the date of CR 
criteria are first met.  
 CR/CRh is defined as the proportion of subjects who reach CR or CRh prior to the initiation 
of any new therapy for AML. 
 Duration of CR/CRh is measured from the date when the CR or CRh criteria are first met 
to the date of relapse or death, whichever occurs first. 
 ORR is defined as the proportion of subjects who reach objective response prior to the 
initiation of any new therapy for AML or MDS. The objective response is defined as CR, 
PR, marrow CR, or HI based on IWG criteria for MDS, and CR, CRi, PR, or (MLFS based 
on ELN criteria for AML. 
 Duration of response (DOR) is measured from the date when the objective response criteria 
are first met to the date of relapse, disease progression or death, whichever occurs first. 
 Time to objective response is defined as the time from the first dose of study treatment to 
the date of objective response criteria are first met.  
 Composite CR rate is the proportion of subjects who reach composite CR prior to initiation 
of any new therapy for AML. The composite CR includes CR and CRi per ELN for AML.
 Duration of composite CR is measured from the date when the composite CR criteria are 
first met to the date of relapse or death, whichever occurs first. 
 Time to composite CR is defined as the time from the first dose of study treatment to the 
date of composite CR criteria are first met. 
 Progression free survival (PFS) is defined as the time from the first dose of study treatment 
to the date of documented disease progression, relapse, or death from any cause, whichever 
occurs first.
 Event free survival (EFS) is defined as the time from the first dose of study treatment to 
the date of documented treatment failure, disease progression, relapse, or death from any 
cause, whichever occurs first. 

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 RBC transfusion independence rate is the proportion of subjects who have a 56-day or 
longer period with no RBC transfusions. 
 Duration of RBC transfusion independence: the duration of RBC transfusion independence 
is measured from the date on which measurement criteria are first met for RBC transfusion 
independence to the first date of RBC transfusion prior to initiation of any new therapy for 
AML or MDS. 
Platelet transfusion independence rate is the proportion of subjects who have a 56-day or 
longer period with no platelet transfusions. 
Duration of platelet transfusion independence: the duration of platelet transfusion 
independence is measured from the date on which measurement criteria are first met for 
platelet transfusion independence to the first date of platelet transfusion prior to initiation 
of any new therapy for AML or MDS. 
 MRD-negative response rate is defined as the proportion of subjects who achieve MRD 
negativity and CR, CRi, or MLFS (subjects with AML) or CR or marrow CR (subjects 
with MDS). Subjects who have no MRD assessment will be considered as non-responder 
for the calculation of MRD-negative response rate.
 Overall survival (OS) is defined as the time from the first dose of study treatment to the 
date of death from any cause. 
The ORR, CR, composite CR, CR/CRh, RBC and platelet transfusion independence rate, and 
MRD-negative response rate will be estimated along with a 95% confidence interval using the 
exact probability method. DOR and time to response will be evaluated, using the Kaplan-Meier 
method, for the subgroup of subjects with a CR, composite CR, CR/CRh, and ORR, respectively. 
Duration of RBC and platelet transfusion independence will be evaluated, using the Kaplan-Meier 
method, for the subgroup of subjects with transfusion independence. The Kaplan-Meier method 
will be used to estimate the PFS/EFS/OS curve and PFS/EFS/OS rate at time of point of interest.  
 
Supplementary analysis may be conducted by applying the IWG 2023 MDS response criteria to 
understand preliminary efficacy further [Zeidan, 2023]. 
9.2.6
Pharmacokinetics 
Plasma concentrations for SL-172154 will be summarized using tabular and graphical format. 
SL-172154 PK parameters (Table 21) will be derived from the plasma concentration vs. time curve 
(using actual dose and collection times) using Phoenix WinNonlin version 6.3 or later (Pharsight 
Corp.), as data permits. SL-172154 PK parameters will be summarized and analyzed using 
appropriate statistical methods. The relationship between PK exposure parameters and ADA, 
safety, efficacy and PD outcome measures may be explored using appropriate graphical and 
statistical methods. 
Table 21 
Serum SL-172154 PK Parameters 

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monitoring will be done, at what level of detail monitoring will be performed, and the 
distribution of monitoring reports. 
Independent audits will be conducted by the Sponsor or designee of the Sponsor to ensure 
GCP and monitoring practices are performed consistently across all participating sites and 
that monitors are following the CMP.
11.
SOURCE DOCUMENTS AND ACCESS TO SOURCE DATA AND DOCUMENTS
11.1
Source Data
Source documents are where data are first recorded, and from which subjects’ eCRF data are 
obtained. These include, but are not limited to, hospital records (from which medical history and 
previous and concurrent medication may be summarized into the eCRF), clinical and office charts, 
laboratory and pharmacy records, diaries, microfiches, radiographs, and correspondence.
11.2
Access to Data
The study monitor, other authorized representatives of the Sponsor, representatives of the IRB/IEC 
or regulatory authorities may inspect all documents and records required to be maintained by the 
Investigator, including but not limited to, medical records (office, clinic, or hospital) and pharmacy 
records for the participants in this study. The clinical trial site will permit access to such records 
to permit study-related monitoring, audits and inspections.  
The study subject’s contact information will be securely stored at each clinical site for Internal use 
during the study. At the end of the study, all records will continue to be kept in a secure location 
for as long a period as dictated by local IRB/IEC and Institutional regulations.  
Study subject research data, which is for purposes of statistical analysis and scientific reporting, 
will be transmitted to and stored by the Sponsor. This will not include the subject’s contact or 
identifying information. Rather, individual subject’s and their research data will be identified by a 
unique study identification number. The study data entry and study management systems used by 
clinical sites and by Sponsor research staff will be secured and password protected. At the end of 
the study, all study databases will be de-identified and archived by the Sponsor. 
11.3 
Data Recording and Record Keeping 
All trial data will be entered on electronic data entry systems that are validated and are maintained 
in accordance with Standard Operating Procedures. The subjects will be identified by a unique 
trial-specific number and/or code in any database. Subject name and any other identifying detail 
will NOT be included in any trial data electronic file. 
12. 
QUALITY ASSURANCE PROCEDURES 
The trial will be conducted in accordance with the current approved protocol, GCP, relevant 
regulations and standard operating procedures. Regular monitoring will be performed according 
to GCP. Data will be evaluated for compliance with the protocol, GCP, and accuracy in relation to 
source documents. Following written standard operating procedures, the monitors will verify that 
the conduct of the clinical trial and data generated, are documented and reported in compliance 
with the protocol, GCP and the applicable regulatory requirements. 

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13.
ETHICS / PROTECTION OF HUMAN SUBJECTS
13.1
Ethical Standard
The Investigator will ensure that this study is conducted in full conformity with Regulations for 
the Protection of Human Subjects of Research codified in 45 Code of Federal Regulations (CFR) 
Part 46, 21 CFR Part 50, 21 CFR Part 56, and/or the International Council for Harmonisation (ICH) 
E6 and consistent with the consensus ethical principles derived from international guidelines 
including the Declaration of Helsinki and Council for International Organizations of Medical 
Sciences International Ethical Guidelines for Biomedical Research Involving Human Subjects 
(2002), or ethical policy statement specific to the country, whichever provides the most protection 
to human subjects.
13.2
Institutional Review Board / Independent Ethics Committee
The protocol, ICF(s), recruitment materials, and all subject materials will be submitted to the 
IRB/IEC for review and approval. Approval of both the protocol and the consent form must be 
obtained before any subject is screened and enrolled. Any amendment to the protocol will require 
review and approval by the IRB/IEC before the changes are implemented to the study. All changes 
to the consent form will be IRB/IEC approved; a determination will be made regarding whether 
previously consented subjects need to be re-consented.
13.3
Informed Consent Process
13.3.1 Consent/Assent and Other Informational Documents Provided to the Subjects
The Investigator or his/her representative will explain the nature of the study to the subject or 
his/her legally authorized representative and answer all questions regarding the study. Subjects 
will be required to sign and date a study consent form prior to any study-related procedures are 
performed if they meet eligibility requirements of the protocol and wish to participate in the trial. 
If applicable, it will be provided in a certified translation of the local language.  
 Subjects must be informed that their participation is voluntary. Subjects or their legally 
authorized representative [defined as an individual or judicial or other body authorized 
under applicable law to consent on behalf of a prospective subject to the subject’s 
participation in the procedure(s) involved in the research] 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 requirements, where 
applicable, and the IRB/IEC or study center. 
 The medical record must include a statement that written informed consent was obtained 
before the subject 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. 
 Subjects must be re-consented to the most current version of the ICF(s) while receiving 
study treatment. 
 A copy of the signed and dated ICF(s) must be provided to the subject or the subject’s 
legally authorized representative. 
 Subjects who are rescreened are required to sign a new ICF.

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The ICF may contain a separate section or a separate ICF may be used for optional exploratory 
research. The Investigator or authorized designee will explain to each subject the objectives of the 
exploratory research. Subjects will be informed that they are free to refuse to participate and may 
withdraw their consent at any time and for any reason during the study period. 
13.3.2 Consent Procedures and Documentation
Informed consent is a process that is initiated prior to the individual’s agreeing to participate in the 
study and continues throughout the individual’s study participation. Extensive discussion of risks 
and possible benefits of participation will be provided to the participants. Consent forms will be 
IRB/IEC approved and the participant and/or the legally authorized representative will be asked to 
read and review the document. The Investigator and/or his/her authorized designee will explain 
the research study to the participant and answer any questions that may arise. All participants will 
receive a verbal explanation in terms suited to their comprehension of the purposes, procedures, 
and potential risks of the study and of their rights as research participants. Participants will have 
the opportunity to carefully review the written consent form and ask questions prior to signing. 
The participants should have the opportunity to discuss the study with their surrogates or think 
about it prior to agreeing to participate. The participant will sign and date the informed consent 
document prior to any procedures being done specifically for the study. The participants may 
withdraw consent at any time throughout the course of the trial. A copy of the signed and dated
informed consent document will be given to the participants for their records. The rights and 
welfare of the participants will be protected by emphasizing to them that the quality of their 
medical care will not be adversely affected if they decline to participate in this study. 
13.4
Participant and Data Confidentiality
Participant confidentiality is strictly held in trust by the participating Investigators, their staff, and 
the Sponsor(s) and their agents. This confidentiality is extended to cover testing of biological 
samples in addition to the clinical information relating to participants. Therefore, the study 
protocol, study documentation, data, and all other study-related information generated will be held 
in strict confidence. No information concerning the study, or the data will be released to any 
unauthorized third party without prior written approval of the Sponsor. 
The study monitor, auditors, other authorized representatives of the Sponsor including the contract 
research organization (CRO), if applicable, representatives of the IRB/IEC or the Sponsor 
supplying study product, the Federal government or its designee and applicable regulatory 
authorities will be granted direct access to the study participants’ original medical records 
(including but not limited to office, clinic, hospital, or pharmacy records), all documents required 
to be maintained by the Investigator, for verification of clinical trial procedures and/or data, 
without violating the confidentiality of the participants, to the extent permitted by the law and 
regulations.  
All documents will be stored safely in a secure location to protect confidentiality. On all trial-
specific documents, other than the signed consent, the participant will be referred to by the trial 
participant identification number/code, not by name. At the end of the study, all records will 
continue to be kept in a secure location for as long a period as dictated by local IRB/IEC and 
Institutional regulations. 

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Study participant research data, which is for purposes of statistical analysis and scientific reporting, 
will be transmitted to and stored at a Sponsor location. This will not include the participant’s 
contact or identifying information. Rather, individual participants and their research data will be 
identified by a unique study identification number. The study data entry and study management 
systems used by research staff at the clinical sites and by authorized representatives of the Sponsor 
will be secured and password protected. At the end of the study, all study databases will be de-
identified and archived at a Sponsor location. 
13.4.1 Research Use of Stored Human Samples, Specimens, or Specimen Data 
Intended Use: Samples and data collected under this protocol may be used to study the 
effects of the investigational drug on how one’s immune system reacts and how the body 
responds to this type of treatment in treating different types of cancers. 
 Storage: Access to stored samples will be limited to specified study personnel/vendor 
personnel. Samples will be identified by unique subject identification codes. Samples and 
data will be stored using subject ID assigned by the Sponsor and Investigators. An 
individual subject may choose to withdraw their consent at any time; however, the Sponsor 
will retain all data previously analyzed and will retain and continue to use any data or 
biological samples collected prior to the consent withdrawal, unless the subject specifically 
requests disposal of their samples. 
14. 
DATA HANDLING AND RECORD KEEPING 
14.1 
Communication and Data Dissemination Plan 
During the study while subjects are receiving treatment with SL-172154, SMC meetings will be 
held to review relevant data with the Investigators or designees. These meetings will be held once 
a month (or more frequently if required) to share safety data and communicate results of ongoing 
analyses. All available safety, PK, PD, and clinical outcome data for all subjects at the time of the 
scheduled SMC Meeting will be reviewed and summarized. Attendees of SMC meetings will 
include but not be limited to clinical Investigators (or designees), the Sponsor Medical Monitor 
and Statistician. The SMC will operate in accordance with the SMC charter which will define roles 
and accountabilities and the process for safety review.  
The Sponsor will remain in constant contact with the clinical sites during the enrollment period to 
ensure that cohort enrollment during the dose escalation of this study is completed as per protocol. 
All dose escalation or safety decisions made by the SMC will be documented in writing with copies 
maintained at each site and the Trial Master File at the Contract Research Organization. 
14.2 
Data Collection and Management Responsibilities 
An eCRF will be used to record all subject data specified by this protocol. The eCRF must be 
completed by designated and trained study personnel. The eCRF will be electronically signed by 
the Principal Investigator or a Sub-investigator listed on the Form FDA 1572 or equivalent. Data 
collection is the responsibility of the clinical trial staff at the site under the supervision of the site 
Investigator. The Investigator is responsible for ensuring the accuracy, completeness, legibility, 
and timeliness of the data reported. All source documents should be completed in a neat, legible 

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manner to ensure accurate interpretation of data. Source documents may include but are not limited 
to, study progress notes, e-mail correspondence, computer printouts, laboratory data, and drug 
accountability records. 
Data reported in the eCRF derived from source documents should be consistent with the source 
documents or the discrepancies should be explained and captured in a progress note and 
maintained in the subject’s official electronic study record.  
Clinical data (including but not limited to AEs, concomitant medications, and expected Ars data) 
and clinical laboratory data will be entered into the study database, a 21 CFR Part 11-compliant 
data capture system provided by the Sponsor. The data system includes password protection and 
internal quality checks, such as automatic range checks, to identify data that appear inconsistent, 
incomplete, or inaccurate. Clinical data will be entered into an electronic data capture system 
directly from the source documents. 
Study data will be entered into eCRFs at the study site. Prior to database lock, programmed 
computer edit checks and manual checks will be performed to check for discrepancies and 
reasonableness of the data. All issues resulting from the computer-generated checks are to be 
resolved as quickly as possible with clarification from study sites.
14.3
Study Record Retention
The Sponsor follows US regulations and ICH guidelines in its retention policy.
US Investigational New Drug (IND) regulations (21CFR 312.62c) require that records and 
documents pertaining to the conduct of this study and the distribution of investigational drug(s) 
including eCRFs, consent forms, laboratory test results, and medication inventory records be kept 
on file by the Principal Investigator for 2 years following the date a marketing application is 
approved for the drug for the indication for which it is being studied. If no application is to be filed 
or if the application is not approved for such indication, these records must be kept until 2 years 
after the investigation has been discontinued and regulatory authorities (i.e., FDA, European 
Medicines Agency, etc.) have been notified. ICH guidelines indicate that study documents should 
be retained until at least 2 years after the last approval of a marketing application in an ICH region 
and until there are no pending or contemplated marketing applications in an ICH region, or at least 
2 years have elapsed since the formal discontinuation of clinical development of the IP. If there is 
a country or institutional policy that specific records and documents be retained for a longer period 
than described above, the applicable sites must comply with those policies in addition to US and 
ICH policies.  
No study records should be destroyed without prior written authorization from The Sponsor, if 
applicable. It is the responsibility of the Sponsor to inform the Investigator when these documents 
no longer need to be retained. 
14.4 
Protocol Deviations 
A protocol deviation is any noncompliance with the clinical trial protocol or GCP requirements. 
The noncompliance may be either on the part of the subject, the Investigator, or the study site staff. 

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As a result of deviations, corrective actions are to be developed by the site and implemented 
promptly.  
It is the responsibility of the site to use continuous vigilance to identify and report deviations to 
the Sponsor Medical Monitor or designee as soon as protocol deviation is identified. All 
documentation regarding protocol deviations will be maintained in the regulatory file. All 
deviations must be addressed in study source documents and reported to Sponsor. Protocol 
deviations must be sent to the local IRB/IEC per their guidelines. The site Principal Investigator 
is responsible for ensuring all study staff understands the local IRB/IEC reporting guidelines and 
adhere to all related requirements and documentation.
14.5
Publications and Data Sharing Policy
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 the International Committee of Medical Journal Editors authorship 
requirements.

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16.3
Contraception Requirements
Definition of Female of Childbearing Potential (FCBP) 
A female subject who is not sterile due to surgery (i.e., from bilateral tubal ligation/occlusion, 
bilateral oophorectomy, bilateral salpingectomy or complete hysterectomy) or who does not have 
a congenital or acquired condition that prevents childbearing or who is not naturally post-
menopausal for at least 12 consecutive months.  
Definition of Female of Non-Reproductive Potential  
Female subjects will be considered of non-reproductive potential if they:  
1. Are post-menopausal if defined as amenorrheic for 12 consecutive months without an 
alternative medical cause. In women < 50 years of age and/or perimenopausal, a high 
follicle stimulating hormone (FSH) level in the post-menopausal range may be used to 
confirm a post-menopausal state in women not using hormonal contraception or hormonal 
replacement therapy. In the absence of 12 consecutive months of amenorrhea, a single FSH 
measurement is insufficient.
OR
2. Have had a hysterectomy and/or bilateral oophorectomy, bilateral salpingectomy or 
bilateral tubal ligation/occlusion, at least 6 weeks prior to screening. 
OR
3. Have a congenital or acquired condition that prevents childbearing. 
Definition of Male of Non-Reproductive Potential 
Male subjects will be considered of non-reproductive potential if they have azoospermia (whether 
due to having had a vasectomy or due to an underlying medical condition).  
Highly Effective Methods of Contraception (<1% failure rate)
A highly effective method of contraception is defined as one that results in a low failure rate (i.e., 
less than 1% per year) when used consistently and correctly. For contraception, subjects should 
comply with one of the following: 
1. Practice abstinence† from heterosexual activity 
OR
2. Use (or have their partner use) a highly effective contraception during heterosexual 
activity. 
Highly effective methods of contraception are‡: 
Single method (one of the following is acceptable): 
intrauterine device (IUD)
vasectomy of a female subject’s male partner
contraceptive rod implanted into the skin 

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 Combination methods 
o Female subjects: the following hormonal contraceptive methods (stable dose at least 3 
months prior to first dose of study treatment) may be used by female subjects and 
requires use of a male condom for the male partner: 
oral contraceptive pill (estrogen/progestin pill or progestin-only pill) 
subcutaneous contraceptive injection  
contraceptive skin patches
vaginal contraceptive rings 
o Male subjects: the following contraception methods may be used by female partners 
and requires use of a male condom for the male subject: 
diaphragm with spermicide  
cervical cap with spermicide (nulliparous women only)  
contraceptive sponge (nulliparous women only)
hormonal contraceptives including oral contraceptive pill (estrogen/progestin-
only pill), contraceptive skin patch, vaginal contraceptive ring, subcutaneous 
contraceptive injection 
†Abstinence (relative to heterosexual activity) can be used as the sole method of contraception if 
it is: (1) consistently employed during the entire period of risk associated with the study drug; (2) 
consistent with the subject’s preferred and usual lifestyle; and (3) considered acceptable by local 
regulatory agencies and IRBs/IECs. Periodic abstinence (e.g., calendar, ovulation, sympto-
thermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception.  
‡If a contraceptive method listed above is restricted by local regulations/guidelines, then it does 
not qualify as an acceptable method of contraception for subjects participating at sites in this 
country/region.
Subjects should be informed that taking the study medication may involve unknown risks to the 
fetus (unborn baby) if pregnancy were to occur during the study. To participate in the study, female
subjects of childbearing potential must use a highly effective method of contraception (i.e., <1% 
failure rate), as described above, at least 14 days prior to initiation of study treatment, and continue 
use during treatment and for 30 days (which exceeds 5 half-lives) after the last dose of SL-172154, 
or for the duration required by local prescribing information after the last dose of azacitidine (i.e., 
for sites in UK at least 6 months after the last dose of azacitidine in either combination regimen). 
Male subjects with female partners of childbearing potential must have azoospermia from a prior 
vasectomy, an underlying medical condition, or agree to use a highly effective method of 
contraception (i.e., <1% failure rate), as described above, during treatment and for 30 days (which 
exceeds 5 half-lives) after the last dose of SL-172154, or for the duration required by local 
prescribing information after the last dose of azacitidine (i.e., for sites in UK at least 3 months; for 
sites in Canada, at least 6 months). 
Pregnancy Status: I
-hCG is elevated as a tumor marker, pregnancy should 
-hCG measurements and 
ultrasound to exclude pregnancy. 
 

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If a nadir as defined in the table above has occurred, give the next course 28 days after the start 
of the preceding course, provided that both the WBC and the platelet counts are greater than 25% 
above the nadir and rising. If a greater than 25% increase above the nadir is not seen by Day 28, 
reassess counts every 7 days. If a 25% increase is not seen by Day 42, reduce the scheduled dose 
by 50%. 
 

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16.6
Recommendation for Toxicity Management of Cytopenias for Venetoclax and 
Azacitidine Combination Regimen 
Recommendations are provided in the following table. If the country-specific prescribing 
information is different, the current local guidelines should be used.  
Beginning with Cycle 2, if the start of a subsequent cycle (e.g., Day 1) is delayed due to venetoclax-
related toxicities (e.g., cytopenia), SL-172154 dose should also be delayed. Consequently, the 
current cycle length is extended (i.e., the cycle lasts longer than 28 days). 
Adverse Reaction
Occurrence
Recommended Action
Grade 4 neutropenia 
with or without fever 
or infection; 
OR
Grade 4 
thrombocytopenia
Prior to achieving 
remissiona
In most instances, do not interrupt venetoclax in 
combination with azacitidine due to cytopenias prior to 
achieving remission 
First occurrence after 
achieving remission and 
lasting at least 7 days 
Delay subsequent cycle of venetoclax in combination 
with azacitidine and monitor blood counts.  
Upon resolution to Grade 1 or 2, resume venetoclax 
at the same dose in combination with azacitidine. 
Note: venetoclax and azacitidine will resume on the 
same day after the interruption to allow for count 
recovery. 
Subsequent 
occurrences in cycles 
after achieving 
remission and lasting 
7 days or longer 
Delay subsequent cycle of venetoclax in combination 
with azacitidine and monitor blood counts.  
Upon resolution to Grade 1 or 2, resume venetoclax 
at the same dose in combination with azacitidine and 
reduce venetoclax duration by 7 days during each of 
the subsequent cycles, such as 21 days instead of 28 
days. 
Note: venetoclax and azacitidine will resume on the 
same day after the interruption to allow for count 
recovery. 
a Recommend bone marrow evaluation.
Source: [VENCLEXTA-USPI, 2020] 
If cytopenia occurs in cycles with reduced venetoclax duration, delay subsequent cycle of 
venetoclax in combination with azacitidine and monitor blood counts. If a 25% increase in nadir
(mid-cycle) has not been achieved within 21 days, consider azacitidine dose adjustment on next 
cycle based on bone marrow cellularity using the most recent value.  

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16.7
Recommendation for the Management of Potential Venetoclax Interactions with 
CYP3A and P-gp Inhibitors
Recommendations from the venetoclax USPI [VENCLEXTA-USPI, 2020] is provided as an 
example in the following table. If the country-specific prescribing information is different, the 
current local guidelines should be used. Please see the country’s current prescribing information 
(e.g., SmPC, or Product Monograph) for additional information.  
Co-administered Drug
Initiation and Ramp-up 
Phase
Steady Daily Dose (After Ramp-up Phase)
Posaconazole
Day 1 – 10 mg
Day 2 –   20 mg 
Day 3 –   50 mg 
Day 4 – 70 mg
Reduce venetoclax dose to 70 mg
Other strong CYP3A inhibitor
Day 1 – 10 mg
Day 2 – 20 mg 
Day 3 –   50 mg 
Day 4 – 100 mg 
Reduce venetoclax dose to 100 mg
Moderate CYP3A inhibitor
Reduce venetoclax dose by at least 50% 
P-gp inhibitor
Source:[VENCLEXTA-USPI, 2020]  
16.8
ECOG Performance Status Criteria
Grade
Description
0 
Normal activity. Fully active, able to carry on all pre-disease performance without restriction 
1 
Symptoms but ambulatory. Restricted in physically strenuous activity, but ambulatory and able 
to carry out work of a light or sedentary nature (e.g., light housework, office work) 
2 
In bed < 50% of the time. Ambulatory and capable of all self-care, but unable to carry out any 
work activities. Up and about more than 50% of waking hours
3 
In bed > 50% of the time. Capable of only limited self-care, confined to bed or chair more than 
50% of waking hours 
4 
100% bedridden. Completely disabled. Cannot carry on any self-care. Totally confined to bed or 
chair.
5 
Dead 
Source: [Oken, 1982]
 

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16.9
Cockcroft-Gault Formula for Creatinine Clearance 
Creatinine clearance (mL/min)1 =  Q x (140 – age [yr]) x ideal body weight [kg]2 
 
 
 
 
 
72 x serum creatinine [mg/dL] 
Q = 0.85 for females 
Q = 1.0 for males 
OR
Creatinine clearance (mL/min)2 =  K x (140 – age [yr]) x ideal body weight [kg]1 
serum creatinine [µmol/L] 
K = 1.0 for females 
K = 1.23 for males 
1. Creatinine clearance has a maximum value of 125 mL/min.  
2. Use ideal body weight (IBW) if body weight > 30% of IBW. Otherwise, use bodyweight 
Calculation of IBW using the Devine Formula [Devine, 1974]: 
Males = 50.0 kg + (2.3 x each inch over 5 ft) or 50.0 kg + (0.906 kg x each cm over 152.4 cm) 
Females = 45.5 kg + (2.3 x each inch over 5 ft) or 45.5 kg + (0.906 kg x each cm over 152.4 cm) 
Example: 
Male, actual body weight = 90.0 kg; height = 68 inches; IBW = 50 + (2.3) (68 – 60) = 68.4 kg 
This subject’s actual body weight is >30% over IBW. Therefore, in this case, the subject’s IBW 
of 68.4 kg should be used in calculating the estimated creatinine clearance 
References:
[McCarron, 1974; Levey, 2006; Levey, 2009] 
 

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16.10 Summary of Changes for Protocol Amendment 01 
This amendment applies to all Investigator sites participating in this study. Text revisions resulting 
from this amendment are incorporated in the body of Protocol Amendment 1.  
Minor editorial changes (including protocol version number and approval date, table of contents) 
as well as minor clarification edits to text are incorporated in this amendment.
This protocol was amended to include the following: 
1. The study design has been revised as follows: 
Monotherapy dose escalation has been incorporated. The option to add azacitidine 
beginning in Cycle 2 for subjects in monotherapy dose escalation cohort has been removed.
o
Study Schema 
o
Section 1.7, Study Rationale 
o
Section 3.0, Study Design 
o
Section 3.1.1, SL-172154 Monotherapy Dose Escalation 
Deleted text in these sections: For those subjects who do not achieve a response (e.g., CR, Cri or 
MLFS in subjects with AML or CR, PR or marrow CR in subjects with MDS) at the end of Cycle 
1, and at the discretion of the investigator, SL 172154 monotherapy may be continued or 
azacitidine may be administered with SL 172154 beginning in Cycle 2 and continued for the 
duration of the treatment period in this study. Subjects who have azacitidine added must follow 
the schedule for SL 172154 dosing and all assessments per the SOA for the SL 172154 and 
azacitidine regimen as described in Section 3.2.1 and Section 6.2. 
If azacitidine was added to SL 172154 for any subject in the monotherapy cohort, safety data from 
Cycle 1 (SL-172154 monotherapy) as well as from Cycle 2 (first cycle with SL-172154 
administered with azacitidine) will be reviewed by the study’s SMC and considered in the 
determination of the SL 172154 starting dose for each of the combination regimen dose escalation 
cohorts (see Section 7.8). Enrolment to the dose escalation combination regimen cohorts will not 
begin until the SMC review and decision is documented. 
Starting dose (1.0 mg/kg) rationale has been updated to indicate that the 3.0 mg/kg dose 
has cleared the DLT evaluation period without a DLT reported in the SL-172154 
monotherapy dose escalation in subjects with ovarian cancer in the ongoing Study SL03-
OHD-104. 
Sec 1.6, Summary of Clinical Data 
Sec 3.0, Description of Study Design 
New text (italics): Of note, following the safety data cut-off date, a third subject initiated 
treatment with SL-172154 at 3 mg/kg and has completed the DLT evaluation period with 
no DLT reported. The next planned dose level in study SL03-OHD-101 is 10 mg/kg. 
Proposed dose levels have been modified from half-log increments to the following SL-
172154 doses: 1 mg/kg, 3 mg/kg, 6 mg/kg, and 10 mg/kg. Should it be needed to better 
define the SL-172154 MTD or maximum administered dose (MAD), dose exploration 

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Deleted text: The planned dose escalation of SL-172154 will not exceed half-log 
increments as outlined in Table 2; additional doses and/or schedules or intermediate doses 
may be explored based on emerging safety, PK and PD data. 
New text (italics): If safety and pharmacodynamic data support exploration of a less 
intensive dosing schedule, then subsequent cohort enrollment on an alternative less 
frequent schedule may be instituted in lieu of the weekly schedule for SL-172154 dosing…. 
Any such evaluation of alternative dosing schedule(s) will be done by protocol amendment. 
A staggered parallel design has been incorporated to explore the combination of SL-
172154 and azacitidine in parallel with the monotherapy dose escalation. The starting dose 
of this combination regimen dose escalation cohort will be one dose level lower than tested 
in the monotherapy dose escalation arm of the study. 
o
Study Schema 
o
Section 3.2.1, SL-172154 Administered with Azacitidine (Dose Escalation) 
Subjects with relapsed/refractory disease (AML or higher-risk MDS) with no more than 4 
(revised from 2) prior therapies for their disease will be enrolled in monotherapy and SL-
172154 + azacitidine Dose Escalation cohorts. Treatment-naïve subjects will not be eligible 
to enroll in these cohorts, with the exception of subjects with subtypes of AML that respond 
very poorly to conventional drugs, such as those with high-risk genetic abnormalities (per 
FDA Guidance, AML: Developing Drugs and Biological Products for Treatment).
o Section 1.7, Study Rationale 
o Section 3.0, Description of Study Design 
o Section 3.1.1, SL-172154 Monotherapy Dose Escalation 
o Section 3.2.1, SL-172154 Administered with Azacitidine (Dose Escalation) 
o Section 4.1, Inclusion Criteria 5 and 6 
 A recommended dose of SL-172154 administered with azacitidine will be identified prior 
to initiation of enrollment to a safety run-in cohort to explore the SL-172154, azacitidine 
and venetoclax combination regimen. Subjects with AML not previously treated will be 
enrolled to this cohort. 
o Section 3.0, Description of Study Design 
o Section 3.2.2, SL-172154 Administered with Azacitidine and Venetoclax (Safety 
run-in) 
o Section 3.3.2, SL-172154 Administered with Azacitidine and Venetoclax in 
Subjects with AML (Dose Expansion)  
 Once a recommended dose of SL-172154 administered with azacitidine is identified in 
dose escalation, enrollment to expansion cohorts of either (1) subjects with higher-risk 
MDS, or (2) AML subjects with at least one TP53 mutation or deletion. Subjects in these 
expansion cohorts will not have previously received treatment for their disease. 
o Section 3.3.1, SL-172154 Administered With Azacitidine in Subjects with Higher-
risk MDS  

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o Section 3.3.3, SL-172154 Administered with Azacitidine in AML Subjects with 
TP53 gene mutation/deletion  
The projected planned sample size, enrollment duration, and study duration has been 
revised based on the revised study design.
o
Synopsis
o
Section 3.1.1, SL-172154 Monotherapy Dose Escalation
o
Section 3.2.1, SL-172154 Administered with Azacitidine (Dose Escalation)
o
Section 3.2.2, SL-172154 Administered with Azacitidine and Venetoclax (Safety 
run-in)
o
Section 9.1.3, Sample Size Determination
2. SL-172154 administration
 Observation of subjects for 4 hours after each SL-172154 administration has been 
added. Longer periods of observation for subjects experiencing IRR or CRS remains 
as previously described in the recommended toxicity management guidelines for each.
o Section 5.1.4, Monitoring Dose Administration 
o Section 6.1 (footnote k), Schedule of Assessments: SL-172154 Monotherapy 
Dose Escalation Cohorts Only 
o Section 6.2 (footnote k), Schedule of Assessments: SL-172154 Combination 
Cohorts, Dose Escalation or Dose Expansion (SL-172154 with azacitidine or 
azacitidine and venetoclax)
 Premedication for primary prophylaxis of IRR with SL-172154 administration is 
already defined in Section 5.1. For further clarification, this information is detailed 
elsewhere in the protocol with this amendment. 
o Synopsis
o Section 3, Description of Study Design
o Section 3.1.1, SL-172154 Monotherapy Dose Escalation 
o Section 3.2.1, SL-172154 Administered with Azacitidine (Dose Escalation)
o Section 3.2.2, SL-172154 Administered with Azacitidine and Venetoclax 
(Safety run-in) 
o Section 3.3.1, SL-172154 Administered With Azacitidine in Subjects with 
Higher-risk MDS 
o Section 3.3.2, SL-172154 Administered with Azacitidine and Venetoclax in 
Subjects with AML (Dose Expansion) 
o Section 3.3.3, SL-172154 Administered with Azacitidine in AML Subjects with 
TP53 gene mutation/deletion (Dose Expansion) 
 Recommendation to have 2 doses of tocilizumab available at the time of SL-172154 
has been added in case of CRS. Provisional plan for alternative management of CRS 
when tocilizumab is not available has been included. 
New text (italics): In case an event of CRS should occur, ensure that at least 2 doses of 
tocilizumab are available prior to each infusion of SL-172154 (see Section 3.8.2 for 
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• 
Grade 3 or greater non-hematologic AE that requires permanent discontinuation of 
SL-172154 
• 
Any Grade 3 or greater non-hematologic AE except for those listed below: 
o 
o Grade 3 anorexia, nausea, vomiting or diarrhea provided that it does not require tube 
feeding, total parenteral nutrition, or require or prolong hospitalization. 
O Grade 3 electrolyte abnormalities that are not associated with clinical signs/symptoms and 
are reversed with appropriate medical intervention
o Grade 3 laboratory abnormalities which resolve to Grade 1 or baseline within 72 hours 
with or without intervention that are not deemed clinically significant by the Safety Monitoring 
Committee (SMC). 
O Indirect/unconjugated hyperbilirubinemia without significant clinical consequences 
o Grade 3 amylase and/or lipase laboratory abnormalities which resolve to Grade 1 or 
baseline within 72 hours with or without intervention that are not associated with clinical 
signs/symptoms or finding on imaging consistent with pancreatitis 
o Grade 3 vomiting and/or Grade 3 nausea that resolves within 72 hours with appropriate 
clinical management
o Grade 3 hypertension that can be controlled (ie, systolic BP < 140 mmHg and diastolic BP 
< 90 mmHg) with medical therapy. 
O Grade 3 diarrhea with no evidence of colitis that resolves within 72 hours with appropriate 
clinical management
o Vitiligo or alopecia of any grade 
4. Concomitant medications section has been modified to reflect additional details regarding 
venetoclax (based on US prescribing information, 2020) 
 Section 3.7.1, Prohibited Medications or Treatments 
o New text (italics): 
• 
For venetoclax cohorts: Use of P-gp substrates concomitantly with 
venetoclax. When azole antifungals that are P-gp inhibitors must be used, they 
are permitted. ;I if concomitant use of P-gp substrate is unavoidable, separate 
dosing of P-gp substrate by at least 6 hours before venetoclax administration. 
If concomitant use of P-gp inhibitor is unavoidable, venetoclax dose should be 
reduced per the prescribing information described in Section 16.6. 
• 
For venetoclax cohorts: Concomitant use of strong or moderate CYP3A4 
inducers at least 14 days or 5 half-lives (whichever is longer) prior to first dose 
of study treatment and throughout the study treatment period. When azole 
antifungals that strong and moderate CYP3A4 inhibitors must be used, they are 
permitted. If strong or moderate CYP3A4 inhibitors must be used, the 
venetoclax dose should be reduced per the prescribing information described 
in Section 16.6 
Section 3.7.2, Medications to be Used with Caution 
o
New text (italics): For subjects receiving venetoclax, concomitant use with a P-
gp inhibitor or a strong or moderate CYP3A inhibitor should be avoided and 
alternative medications should be considered. In the presence of unavoidable 

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strong and moderate CYP3A4 inhibitors or P-gp inhibitor, the venetoclax dose 
should be reduced per the prescribing information described in Section 16.6. 
5. Recommendations for management of IRR has been updated as follows (Section 3.8.1): 
Recommendation for additional monitoring of vital signs with any grade of IRR (also 
included for any grade of CRS in Section 3.8.2), new text (italics): 
Vital signs should be measured every 15 minutes for the first hour of SL-172154 
infusion and then every 30 minutes for the second hour and through 1 hour after the 
end of the SL-172154 infusion (NOTE: this timing allows for variable durations of SL-
172154 infusions). 
o
Also included in Schedule of Assessments (footnote d), Section 6.1 and Section 
6.2 
 Reference to CRS management has been removed from Section 3.8.1 and is now 
included as a separate toxicity management table in Section 3.8.2. 
6. Recommendations for management of CRS has been added
 Section 3.8.2, new section in Protocol Amendment 1 
 Section 3.1, new text (italics) added to allow for reduced increments of SL-172154 
dose escalation in the event that Grade 2 or 3 event of CRS is reported in the study: 
During dose escalation, the following guideline should be followed if an event of CRS 
occurs on Cycle 1 Day 8 or later:
o 
Grade 2 CRS: SL-172154 dose should not be escalated by more than 50% 
between subsequent dose levels 
o 
Grade 3 CRS: SL-172154 dose should not be escalated by more than 25% 
between subsequent dose levels 
 Section 5.1.1, new text (italics) 
o Premedication with corticosteroid will be given to all subsequent subjects 
following the first case of 
7. Recommendations for management of hepatotoxicity has been modified (Section 3.8.3) 
 Definition of Hy’s Law has been revised; in addition, the requirement for Grade 3 
elevations to be evaluated for potential DLT has been included and reflects the updates 
to the DLT criteria [new text (italics)]: Discontinue SL-172154 for Hy’s Law as 
follows: 
concomitant AST or ALT > 3 x ULN and total bilirubin > 2 x ULN; or in subjects who 
enroll with AST/ALT/total bilirubin > ULN who experience concomitant AST or ALT 
> 3 x baseline and total bilirubin > 2 x baseline
found to explain the combination of increased aminotransferases and total bilirubin, 
such as viral hepatitis A, B or C, preexisting or acute liver disease, or another drug 
capable of causing the observed injury. Grade 3 ALT/AST or bilirubin will be evaluated 
to determine if events meet the DLT criteria. 
 Modification made to recommendation for Grade 2 events (new text in italics):  
 Hold SL 172154 Dose reduce SL-172154 by one dose level

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 Assessments as above, Monitor liver function ~every 3 days. If persistent or rising 
liver chemistries or significant clinical symptoms, interrupt SL-172154. 
 Consider hepatology consult and liver biopsy is optional.  
 If persistent or rising liver chemistries or significant clinical symptoms and If an 
immune etiology is suspected, start oral prednisone 0.5-1.0 mg/kg/day (or 
equivalent of methylprednisolone) with 4-week taper.
 Resume SL-
prednisone or equivalent 
8. Recommended dose modification of SL-172154 has been added  
Section 3.8.4, Management of Non-hematologic and Hematologic AEs Not Specified 
o
New table describing SL-172154 dose reduction recommendations 
o
Deleted text: No SL 17215 dose modification (dose reduction) will be permitted. 
Dose delay is recommended as the only method or managing SL-172154 related 
toxicities. 
 Section 3.8, Toxicity Management for SL-172154 
o New text (italics): Table 5 describes the dose reductions to be used for AEs that are 
considered by the Investigator to be possibly related or related to treatment with 
SL-172154. Only one level dose reduction is permitted for AE management and 
then SL-172154 administration should be interrupted. Investigators always have 
the option to perform a more conservative dose modification if clinically indicated 
(i.e. dose interruption as opposed to dose reduction). Any adverse event deemed to 
be related to SL-172154 that requires a dose hold of more than 28 days will result 
in permanent discontinuation of SL-172154.
Table 5  SL-172154 Dose Reduction for Management of Toxicities 
STARTING DOSE 
LEVEL (mg/kg) 
DOSE LEVEL REDUCTION (mg/kg)
0.3 
Interrupt SL-172154 until toxicity resolves to </= 
grade 1 or baseline and then restart at same dose 
level.
1.0
0.3
3.0
1.0
6.0
3.0
10
6.0
9. A sample for SL-172154 PK has been added at 0.5h after the end of SL-172154 infusion on 
Cycle 1 Day 1 
 Section 6.1.1, PK, ADA, and Cytokines Sampling Schedule – Peripheral Blood (SL-
172154 Monotherapy Dose Escalation Cohorts Only) 
 Section 6.1.2, PK, ADA, and Cytokines Sampling Schedule – Peripheral Blood (SL-
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10. Additional safety monitoring for subjects receiving venetoclax, based on US Prescribing 
Information (2020), has been included (new text, italics): 
For subjects receiving venetoclax, the following additional laboratory assessments should be 
performed:  
chemistry tests to monitor for TLS should be drawn (calcium, inorganic phosphorus, 
potassium, uric acid and creatinine) on the first, second and third day of venetoclax 
dosing at predose (within 4 hours prior to dosing) and 6 – 8 hours post-dose during 
ramp-up, and 24 hours after reaching final dose 
INR should be monitored more frequently in subjects using warfarin concomitantly 
with venetoclax
Section 6.4.7, Local and Central Laboratory Assessments 
Section 6.2, Schedule of Assessments: SL-172154 Combination Cohorts, Dose Escalation or 
Dose Expansion (SL-172154 with azacitidine or azacitidine and venetoclax) 
11. Clarification that the collection timepoints of bone marrow aspirates to send to central 
laboratory for research purposes is at select timepoints and not with every bone marrow 
performed for disease assessment during this study. 
 Section 6.8, Bone Marrow Assessments 
 Section 6.1 and Section 6.2, Schedule of Assessments (footnote n) 
A sufficient bone marrow aspirate must be collected for clinical disease assessment and biomarker 
assessments Bone marrow aspirate samples must be collected for all subjects from the bone 
marrow performed at the following timepoints: 
 Screening (baseline) 
 End of Cycle 1. 
 End of Cycle 4
 End of Cycle 13 
If a bone marrow is performed for subjects with a CR, marrow CR, or MLFS at any unscheduled 
timepoint prior to the end of Cycle 13, a portion of the bone marrow aspirate should also be sent 
to the central laboratory for exploratory research. 
12. Allowance to monitor either blood urea nitrogen or urea as well as either bicarbonate or CO2
has been added to allow flexibility of standard analytes as local laboratories. 
 Section 6.4.7 (Clinical Chemistry in Local Clinical Labs table; new text in italics) 
o Blood urea nitrogen or Urea 
o Bicarbonate or CO2
13. ELN response criteria for AML table was modified to incorporate description of relapse 
(hematologic and molecular relapse); language was previously included as text following the 
table.
 Section 8.1.1 

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7 days. If a 25% increase is not seen by day 42, reduce the scheduled dose by 
50%. 
17. Recommendation for management of potential venetoclax interactions with CYP3A and P-gp 
inhibitors has been added as Appendix 16.6 (new section); reflects US Prescribing Information 
(2020).
 

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16.11 Summary of Changes for Protocol Amendment 02 
This amendment applies to all Investigator sites participating in this study. Text revisions resulting 
from this amendment are incorporated in the body of Protocol Amendment 2.  
Minor editorial changes (including protocol version number and approval date, table of contents) 
as well as minor clarification edits to text are incorporated in this amendment.
This protocol was amended to include the following: 
1) Reference to stem cell transplantation (SCT) has been revised to hematopoietic cell 
transplantation (HCT) throughout the document. Hematopoietic cell transplantation (HCT), 
hematopoietic stem cell transplantation (HSCT), or stem cell transplantation (SCT) have been 
interchangeably used to refer to the same therapeutic modality. The Center for International 
Blood and Marrow Transplant Research (CIBMTR) and the American Society for 
Transplantation and Cellular Therapy (ASTCT) has recently started to standardize the wording 
to HCT. Thus, the protocol will follow the standardized word. 
2) Rationale for exploring novel agent in combination with azacitidine for AML subjects with 
TP53m has been included. 
 Sec 1.3
New text: Nonetheless, the benefit of improved median OS from the combination of azacitidine 
and venetoclax has not been observed in TP53-mutated AML patients. No benefit in OS was 
observed in this poor prognostic subgroup although an increase in ORR was observed (55% vs. 
0% in patients treated by the combination of azacitidine and venetoclax vs. the combination of 
azacitidine and placebo, respectively) [DiNardo, 2020a; Cluzeau, 2021]. This is in line with other 
retrospective cohorts of TP53-mutant AML patients treated with decitabine, another 
hypomethylating agent, and venetoclax. Despite use of extended decitabine courses, these cohorts 
demonstrated a median OS of approximately 6 months regardless of venetoclax receipt [Maiti, 
2019; DiNardo, 2020a; Venugopal, 2021]. These clinical findings are supported by recent 
mechanistic observations identifying TP53 mutation to be a direct driver of venetoclax resistance 
[Nechiporuk, 2019; DiNardo, 2020b]. In total, these data demonstrate that the addition of 
venetoclax to azacitidine has not provided a significant improvement for AML patients with TP53 
mutation, and thus the investigation of novel agents in combination with azacitidine is warranted. 
3) Summary of study design description that was available in other sections of the protocol in 
Amendment 1 has also been added to the Study Rationale (Sec 7.1) 
Study SL03-OHD-104 will initially enroll approximately 5 subjects with relapsed or refractory 
disease (MDS or AML) to SL-172154 monotherapy dose escalation cohort at the starting dose of 
1 mg/kg SL-172154. Subjects will be enrolled into sequential dose levels of SL-172154 and 
assessed for DLT during the first 28 days. This will inform the safety, tolerability, efficacy, PK, 
PD, and preliminary anti-tumor activity profile of SL-172154 monotherapy by dose level. 
While clinical response is possible with SL-172154 monotherapy, limited clinical responses have 
been observed with other investigational agents targeting CD47 and CD40 administered as 
monotherapy [Vonderheide, 2007; Vyas, 2018; Sallman, 2019a; Sikic, 2019]. The mechanism of 

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b. Prior hydroxyurea or other supportive care in the form of transfusions or growth factors 
will not be considered prior therapy.  
c. Subjects who have undergone allo-SCT HCT are eligible if they are at least 6 months 
post-SCT HCT, have relapsed AML or MDS as defined above, are not on treatment or 
prophylaxis for GVHD for at least 6 weeks before administration the first dose of study 
treatment, and have no active GVHD.  
In addition, previously untreated subjects are eligible for this cohort when the following 
criteria are met:
a.
Previously untreated subjects with AML with known adverse cytogenetics who fall into 
the adverse ELN risk group and who are unlikely to benefit from standard intensive 
induction therapy or refuse intensive induction therapy at time of enrollment are also 
eligible. 
b. Previously untreated subjects with MDS with documentation of at least one TP53 gene 
mutation or deletion based on local test. Prior lenalidomide or other supportive care 
in the form of transfusions or growth factors is allowed. 
7) Language has been added regarding administration of COVID-19 vaccinations.
 Sec 3.7.1 Prohibited Medications or Treatments 
 Sec 4.2 (exclusion criterion 7) 
(Prohibited Medications or Treatments) Live attenuated vaccines during the study through 30 
days after the last dose of SL-172154, the exception is that vaccines for COVID-19 are 
permitted. 
8) Language has been added to allow potential for continuation of study treatment with equivocal 
disease progression. 
 Sec 3.12 (new text) 
A subject meeting the response criteria of relapsed or progressive disease, or determination 
of clinical progression is considered a sufficient reason to discontinue study drug treatment. 
However, if the determination of progression is equivocal, the Investigator may continue study 
drug treatment until it is considered to be no longer beneficial to the subject. 
9) Collection of transplant information has been added for subjects that discontinue study 
treatment when (s)he becomes eligible for and agrees to transplant.  
 Sec 3.13 
 Sec 6.1 (footnotes m, o) 
 Sec 6.2 (footnotes m, o) 
 Sec 6.11 
(Sec 3.13) New text 
In addition, for subjects that proceed to hematopoietic cell transplantation (HCT), HCT-
relevant information, will be collected and entered in the EDC. 
(Sec 6.11) New Section 
In addition to the assessments noted in the Schedule of Assessment table (Section 6.1 or Section 
6.2) to be performed at the Post Treatment Visit, additional information should be collected 

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regarding the subject. Beginning at the Post Treatment Visit and during Survival Follow-up, 
the start date and agent name of subsequent anticancer therapy(ies) for AML or MDS will be 
collected and entered in the EDC.  
In addition, for subjects that proceed to HCT, HCT-relevant information (e.g., type of 
transplant, GVHD and transplant-related complications) may also be collected and entered in 
the EDC. Should the subject be followed by another physician, the study Investigator should 
contact the subject’s hematologist/oncologist/transplant physician to obtain this information. 
10) To address patient safety as well as the integrity of the study data in clinical trials performed 
during the COVID-19 pandemic, Shattuck Labs has developed a COVID-19 Risk Assessment 
Policy. This policy is a separate, living document outside of individual clinical study protocols. 
 Sec 3.15 (New Section: COVID-19 Risk Assessment) 
Shattuck Labs has developed a separate COVID-19 risk assessment policy to address conduct 
of clinical trials during the Coronavirus Disease 2019 (COVID-19) pandemic to ensure patient 
safety as well as management of potential implications to data integrity. A copy of this 
document can be made available upon request. 
11) Therapies not considered a prior line of therapy for the previously untreated subjects with MDS 
enrolled to the SL-172154 + azacitidine dose escalation cohort has been revised. Hydroxyurea 
is typically used for myeloproliferative disorders (MDS/MPN) and high blast count and not 
generally used in patients with MDS. As patients who have developed MDS as a result of MPN 
are excluded in this study, it would be appropriate to remove the allowance for prior 
hydroxyurea in relation to MDS. 
 Synopsis (inclusion criterion 7) 
 Sec 4.2 (inclusion criterion 7) 
[Dose Expansion Cohort Part A: SL-172154 Administered With Azacitidine]: Subjects 
diagnosed with MDS must be previously untreated. Prior MDS therapy with lenalidomide, 
hydroxyurea or other supportive care in the form of transfusions or growth factors is allowed
will not be considered prior therapy. Up to 1 cycle of prior therapy with a hypomethylating 
agent is permitted. Subjects with newly diagnosed treatment-related MDS are also eligible for 
enrollment 
12) Blood sample that was planned for exploratory MRD analysis is now being collected for 
exploratory assessment of T cell repertoire. Although there is a scientific interest as to how 
MRD detection differs between using bone marrow and peripheral blood samples, this study 
will assess MRD only in bone aspirate. TCR analysis will provide how T cell repertoire 
changes and T cells clonally expand during SL-172154-based treatment, which may provide 
the relevant information relating to the MOA of SL-172154. 
 Synopsis  
 Sec. 2 
 Sec 6.1 
 Sec 6.2 
 Sec 6.4.7 

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 Sec 6.2 and 6.2.1  
16) As confirmation of TP53 gene mutation/deletion for subjects enrolled in Dose Escalation (SL-
172154 + azacitidine) or Dose Expansion (Part C) is performed by the Investigator using 
historical information and not a study-specific procedure, it has been removed from the 
Schedule of Assessment table in Section 6.2. 
Additionally, clarification regarding local confirmation of TP53m has been added in Section 
6.8.1: 
Documentation of TP53 gene mutation/deletion by local testing will serve as entry criterion 
for subject with previously untreated MDS with TP53m enrolled in the Dose Escalation Cohort 
of SL-172154 administered with azacitidine and for subjects with AML enrolled in Part C 
Cohort of Dose Expansion. 
17) The collection of a subject’s transfusion history prior to enrollment on this study has been 
modified to better reflect the AML or MDS populations. 
 Sec 6.1 
 Sec 6.2  
 Sec 6.10 
From 8 weeks (subjects with MDS) or from 4 weeks (subjects with AML) prior to the first dose 
throughout end of treatment date. 
18) The protocol-specified schedule of bone marrow for disease assessments has been modified to 
allow less frequent procedures for subjects that continue on study treatment for longer than 
approximately 1 year as these subjects are anticipated to have better disease control. Although 
bone marrow aspirate (or biopsy) is essential to evaluate disease assessment, the procedure is 
invasive and painful for patients. Thus, flexibility of mandatory bone marrow examination to 
accommodate institutional/regional standard practice has been added. 
 Sec 6.8 
 Sec 6.1 
 Sec 6.2 
Bone marrow for disease assessments should be performed at the following timepoints: 
 Screening (baseline)  
 End of Cycle 1 (performed -7 days of Cycle 2 Day 1 and resulted prior to the administration 
of treatment for Cycle 2)  
o For AML subjects with resistant disease at end of Cycle 1, a repeat bone marrow 
must be performed at the end of Cycle 2 (performed ±7 days of Cycle 3 Day 1) 
based on the hematologic recovery to confirm response 
 End of every 3 Cycles thereafter until Cycle 13 (e.g., End of Cycle 4, Cycle 7, etc. Cycle 
10, Cycle 13) 
 End of every 6 Cycles beyond Cycle 13 (e.g., End of Cycle 19, Cycle 25, etc.) 
 At time of relapse/progression: if clinically feasible  

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 A bone marrow assessment is strongly encouraged when a subject discontinues study 
treatment as (s)he becomes eligible for and is planned to proceed to HCT. 
 In the event that a subject experiences prolonged response or stable disease beyond 
Cycle 7, less frequent bone marrow assessment is permitted after consultation with the 
Sponsor Medical Monitor. 
19) The protocol-specified schedule of collection of bone marrow aspirate for exploratory research 
has been modified. Submission requirements of bone marrow specimen has been changed to 
add timepoints at the end of Cycle 2 (select AML subjects only), end of Cycle 7, end of Cycle 
10, and every 6 cycles (e.g., 6 months) beyond Cycle 13, which is the second year of the study 
treatment. Assessing minimal residual disease (MRD) is clinically meaningful in the patients 
who are experiencing “good” disease control such as CR because these patients may have 
deeper response typically represented by negative MRD.  
Sec 6.8
Sec 6.1
Sec 6.2
Submission of a sufficient bone marrow aspirate for central laboratory analysis must should be 
collected for clinical disease assessment and exploratory research biomarker assessments from the 
bone marrow performed at the following timepoints (each with a 7 day window): 
 Screening (baseline) 
 End of Cycle 1 (e.g., performed -7 days of Cycle 2 Day 1) 
o 
End of Cycle 2 for AML subjects with resistant disease at end of Cycle 1 (performed 
±7 days of Cycle 3 Day 1) 
 End of Cycle 4 
 End of Cycle 7
 End of Cycle 10 
 End of Cycle 13 
 Every 6 cycles (e.g. 6 months) thereafter 
 When a subject discontinues study treatment as (s)he becomes eligible for and is planned 
to proceed to HCT if a bone marrow assessment is performed 
If a bone marrow is performed at any unscheduled timepoint prior to the end of Cycle 13 for 
subjects with AML who achieve CR, marrow CR Cri, or MLFS, or for subjects with MDS who 
achieve CR or marrow CR at any unscheduled timepoint prior to the end of Cycle 13, a portion 
of the bone marrow aspirate should also be sent to the central laboratory for exploratory 
research. 
20) Assessment of cyotogenetic CR per 2003 IWG AML response criteria has been added for the 
response evaluation of subjects with AML. Cytogenetic CR was included as a part of 2003 
IWG AML response criteria. Due to the nature of a phase 1 study, the locally assessed 
cytogenetic information will help to obtain insight of efficacy signal from SL-172154 or its 
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Sec 8.1.1 
All subjects who completed at least one cycle of study treatment will be assessed by the 
Investigators using the 2017 ELN Response Criteria for AML as described below. Assessments 
will be performed at the end of Cycle 1 and every 3 cycles thereafter for response assessment 
as described in Section 6.8. For subjects with resistant disease at end of Cycle 1, a repeat bone 
marrow will be performed at the end of Cycle 2. Additionally, for subjects with cytogenetic 
abnormalities at the baseline bone marrow test, cytogenetic CR should be reported per 2003 
IWG AML response criteria [Cheson, 2003] when the result is available. Cytogenetic CR is 
defined as reversion to a normal karyotype at CR. 
Sec 8.1.2 
Cytogenetic CR has been included in the IWG response criteria table
Cytogenetic 
CR
Disappearance of the chromosomal abnormality without appearance of 
new ones in subjects who achieve CR
21) Assessment of CRh (complete remission with partial hematologic recovery) has been added 
for the response evaluation of subjects with AML Some patients who achieved less than CR 
derive benefit from particular types of AML therapy. CRh (complete remission with partial 
hematologic recovery) is an emerging concept in the management of AML. 
Sec 8.1.1 (new text) 
Additionally, CRh (complete remission with partial hematologic recovery) will be evaluated 
separately from the ELN response criteria. CRh is defined as all CR criteria except for partial 
hematological recovery of peripheral blood counts (e.g., platelets >50 x 10^9/L and ANC >0.5 
x 10^9/L), as described in Figure 2. 
Figure 2 Hematologic Recovery Requirements for CR, CRh, and Cri 
ANC: absolute neutrophil count; CR: complete remission; Cri: complete remission with incomplete hematologic 
recovery; MLFS: morphologic leukemia-free state; CRh: complete remission with partial hematologic recovery

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To determine transfusion dependence or independence, RBC transfusion history should be 
collected for 4 weeks prior to initiating study treatment for AML subjects regardless of 
hemoglobin level. 
22) Based on the revisions described in Amendment 2 that are related to efficacy assessment, the 
following changes have been made to the efficacy analyses descriptions in the statistical 
analysis section of the protocol.  
Section 9.2.5 
The primary efficacy analysis will include the following endpoints: 
 CR is defined as the proportion of subjects who reach CR prior to the initiation of any 
new therapy for AML or MDS.  
 Duration of CR is measured from the date when the CR criteria are first met to the date of 
relapse or death, whichever occurs first. 
 Time to CR is defined as the time from the first dose of study treatment to the date of CR 
criteria are first met. 
 CR/CRh is defined as the proportion of subjects who reach CR or CRh prior to the 
initiation of any new therapy for AML. 
 Duration of CR/CRh is measured from the date when the CR or CRh criteria are first met 
to the date of relapse or death, whichever occurs first. 
 ORR is defined as the proportion of subjects who reach objective response prior to the 
initiation of any new therapy for AML or MDS. The objective response is defined as CR, 
Partial Remission (PR), marrow CR, or hematologic improvement based on IWG criteria 
for MDS, and CR, CR with incomplete hematologic recovery (CRi), PR, or morphologic 
leukemia-free state (MLFS) based on ELN criteria for AML.
 Duration of Response (DOR) is measured from the date when the objective response 
criteria are first met to the date of relapse, disease progression or death, whichever occurs 
first. 
 Time to objective response is defined as the time from the first dose of study treatment to 
the date of objective response criteria are first met.  
 Composite CR rate is the proportion of subjects who reach composite CR prior to initiation 
of any new therapy for AML. The composite CR includes CR and marrow CR per IWG 
for MDS and CR and CRi per ELN for AML. Partial remission rate is the proportion of 
subjects who achieve a PR as the best response prior to initiation of any new therapy. 
 Duration of composite CR is measured from the date when the composite CR criteria are 
first met to the date of relapse or death, whichever occurs first. 
 Time to composite CR is defined as the time from the first dose of study treatment to the 
date of composite CR criteria are first met. 
 Progression Free Survival (PFS) is defined as the time from the first dose of study 
treatment to the date of documented disease progression, relapse, or death from any cause, 
whichever occurs first.

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 EFS is defined as the time from the first dose of study treatment to the date of documented 
treatment failure, disease progression, relapse, or death from any cause, whichever occurs 
first.
 RBC transfusion independence rate is the proportion of subjects who have a 56-day or 
longer period with no RBC transfusions. 
Duration of RBC transfusion independence: the duration of RBC transfusion 
independence is measured from the date on which measurement criteria are first met for 
RBC transfusion independence to the first date of RBC transfusion prior to initiation of 
any new therapy for AML or MDS. 
Platelet transfusion independence rate is the proportion of subjects who have a 56-day or 
longer period with no platelet transfusions. 
 Duration of platelet transfusion independence: the duration of platelet transfusion 
independence is measured from the date on which measurement criteria are first met for 
platelet transfusion independence to the first date of platelet transfusion prior to initiation 
of any new therapy for AML or MDS. 
 MRD Negative response rate is defined as the proportion of subjects who achieve MRD 
negativity and composite CR, CRi, or MLFS (subjects with AML) or CR or marrow CR 
(subjects with MDS). Subjects who have no MRD assessment will be considered as non-
responder for the calculation of MRD negative response rate. 
 Overall Survival (OS) is defined as the time from the first dose of study treatment to the 
date of death from any cause. 
The ORR, CR, composite CR, CR/CRh, RBC and platelet transfusion independence rate, and 
MRD negative response rate will be estimated along with a 95% confidence interval using the 
exact probability method. Duration of response and time to response will be evaluated, using the 
Kaplan-Meier method, for the subgroup of subjects with a CR, composite CR, CR/CRh, and ORR, 
respectively. Duration of RBC and platelet transfusion independence will be evaluated, using the 
Kaplan-Meier method, for the subgroup of subjects with transfusion independence. The Kaplan-
Meier method will be used to estimate the PFS/EFS/OS curve and PFS/EFS/OS rate at time of 
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16.12 Summary of Changes for Protocol Amendment 03 
This amendment applies to all Investigator sites participating in this study. Text revisions resulting 
from this amendment are incorporated in the body of Protocol Amendment 03.  
Minor editorial changes (including protocol version number and approval date, table of contents) 
as well as minor clarification edits to text are incorporated in this amendment.
This protocol was amended to include the following: 
 Protocol Synopsis – all changes as noted below are included in synopsis, as needed. 
 Study Schema was revised to better reflect the current study design. 
 Section 1.6 Summary of Clinical Data was updated with data as of 12 September 2022. 
Additional details are available in the SL-172154 IB. Incorporation of this data is also in 
Section 1.81, Section 3. 
 Section 1.8.1 Potential Risks – additional explanation has been added to the Safety profile of 
SL-172154 in the context of azacitidine and venetoclax: 
“Anemia without evidence of hemolysis, and transient decreases in lymphocyte and platelet counts 
have been observed with SL-172154. These hematologic effects are not a consequence of 
myelosuppression. The expression of CD40 on platelets and B cells may explain the hematologic 
effects observed with CD40 agonists. Inwald et al. showed that the binding of sCD40L to CD40 
induces P-
IIb 3 without inducing platelet aggregation 
[Inwald 2003]. We and others have shown that ligation of CD40 receptor on B cells by CD40 
agonists lead to transient egress of B cells from the circulation [Lakhani 2021; Vonderheide 
2007]. Thus, other than fatigue, It is not expected that SL-172154 would exacerbate the 
myelosuppression toxicities commonly observed with azacitidine alone or in combination with 
venetoclax.”
 Contraception requirement has been clarified and country-specific requirements have been 
included: 
Inclusion Criteria #14) “Females of childbearing potential (FCBP) must have a negative serum or 
urine pregnancy test within 72 hours of the first dose of study treatment. NOTE: females are 
defined as being of childbearing potential unless they are surgically sterile (i.e., have undergone 
a complete hysterectomy, bilateral tubal ligation/occlusion, bilateral oophorectomy or bilateral 
salpingectomy), have a congenital or acquired condition that prevents childbearing or are 
naturally post-menopausal for at least 12 consecutive months. Documentation of post-menopausal 
status must be provided. To avoid pregnancy, FCBP must start using a highly effective method of 
contraception (i.e., <1% failure rate), as described in Section 16.3, at least 14 days prior to 
initiation of study treatment, and continue use during treatment and for 30 days (which exceeds 5 
half-lives) after the last dose of SL-172154, or for the duration required by local prescribing 
information after the last dose of azacitidine (i.e., for sites in UK and Spain, at least 6 months after 
the last dose of azacitidine in either combination regimen).” 
Inclusion criteria #14) “Male subjects with female partners must have azoospermia from a prior 
vasectomy, an underlying medical condition, or agree to use a highly effective method of 
contraception (i.e., <1% failure rate) during treatment and for 30 days (which exceeds 5 half-
lives) after the last dose of SL-172154, or for the duration required by local prescribing 
information after the last dose of azacitidine (i.e., for sites in UK and Spain, at least 3 months; for 
sites in Canada, at least 6 months).” 

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 Peripheral blood collection for receptor occupancy analysis has been added: 
“Receptor occupancy of SL-172154 on CD47 and CD40 in peripheral blood cells will be measured 
by flow cytometry. This analysis will provide evidence that SL-172154 is engaging the expected 
targets and allows receptor occupancy to be calculated and assessed across dose groups.” 
o Section 6.1, Section 6.1.1, Section 6.2, Section 6.2.1, Section 6.4.7, Section 6.7.2. 
 Peripheral blood collection for hematology and clinical chemistry analysis has been added.
 SL-172154 Monotherapy Dose Escalation Cohorts  
Hematology has been added on Cycle 1 Day 3. 
o Table 6.1 
Hematology and clinical chemistry have been added on Cycle 2 Day 2.  
o Table 6.1 
Blood sample collection for cytokines has been moved from Cycle 1 Day 4 (72 hour 
post-EOI) to Cycle 1 Day 2 (24 hour post-EOI).  
o Tables 6.1 and 6.1.1 
Blood sample collection for cytokines has been moved from Cycle 2 Day 3 (48 hour 
post-EOI) to Cycle 2 Day 2 (24 hour post-EOI).  
o
Tables 6.1 and 6.1.1 
 SL-172154 Combination Cohorts, Dose Escalation or Dose Expansion (SL-172154 with 
Azacitidine or Azacitidine and Venetoclax) 
Hematology has been added on Cycle 1 Day 4, Cycle 2 Day 4, Cycle 2 Day 9 and 
Cycle 2 Day 23.  
o Table 6.2 
Hematology and clinical chemistry have been added on Cycle 2 Day 3.  
o Table 6.2 
Blood sample collection for cytokines has been moved from Cycle 1 Day 5 (72 hour 
post-EOI) to Cycle 1 Day 3 (24 hour post-EOI).  
o Tables 6.2 and 6.2.1 
Blood sample collection for cytokines has been moved from Cycle 2 Day 4 (48 hour 
post-EOI) to Cycle 2 Day 3 (24 hour post-EOI).  
o Tables 6.2 and 6.2.1 
 Monitoring time after completion of SL-172154 infusion has been shortened at Cycle 4 Day 1 
and beyond when subjects meet required criteria (Section 5.1.4).  
 An alternative schedule of azacitidine, 4-2-3 schedule (i.e. azacitidine administration on Days 
1-4 and 7-9), has been added.  
 The condition to initiate the enrollment of the dose escalation cohort of the combination of 
SL-172154 and azacitidine has been clarified.  
“When the SL-172154 monotherapy cohort completes the DLT evaluation period in Dose Level 2 
(3.0 mg/kg), enrollment may begin in parallel to the dose escalation cohorts investigating 
SL-172154 (starting dose 1.0 mg/kg) administered with azacitidine to maximize the potential for 
clinical benefit to participating subjects.” 

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o Study Schema footnote, Section 1.7, Section 3, Section 3.3.1, Section 3.2.1 
 The following sentence has been removed because the dose of 6.0 mg/kg is not currently 
included in the study, SL03-OHD-101.  
Doses explored in SL03 OHD 104 will not exceed the highest dose cleared for safety in SL03
OHD-101. 
o study schema footnote, section 1.8.1, 3.1.1, 3.2.1, 3.2.2, 7.8 
The following rule has been added to SL03-OHD-104: 
“To escalate the dose of SL-172154 in combination with azacitidine, the corresponding 
monotherapy dose level for SL-172154 will have been cleared for safety.” 
o study schema footnote, section 3.2.1 
 Washout period of CYP3A inducers in Section 3.7.1 (Prohibited Medications or Treatments) 
has been updated to be consistent with the washout period defined in the Exclusion Criterion 
6 in Section 4.2. 
 Clarifications have been added to Section 3.7.1 for use of immunosuppressive medications and 
systemic corticosteroids:  
“Immunosuppressive medications for primary prophylaxis against IRRs are not permitted. 
Subjects who require immunosuppressive medications (e.g., corticosteroids) for management of 
IRRs should be managed per Toxicity Management Guidelines in Section 3.8. 
o Immunosuppressive medications (except to treat a drug-related AE). 
o Systemic corticosteroids > 10 mg daily prednisone equivalent except that the followings are 
permitted.  
o Topical, intranasal, inhaled, ocular, intraarticular corticosteroids. 
o Physiological doses of replacement steroid (e.g., for adrenal insufficiency). 
o A brief course of corticosteroids for prophylaxis (e.g., contrast dye allergy) or for 
treatment of non-autoimmune conditions (e.g., transfusion reactions, delayed-type 
hypersensitivity reaction caused by contact allergen). 
o Treatment for a drug-related AE (See Section 3.8).” 
 Clarification of permitted and prohibited steroid use has also been updated in Section 4.2 
(Exclusion Criterion 6): 
o “Physiological doses of replacement steroid (e.g., for adrenal insufficiency) not to 
exceed 10 mg/day of prednisone or equivalent 
o Steroid premedication for hypersensitivity reactions (e.g., reaction to IV contrast) or a 
brief course of treatment of non-autoimmune conditions (e.g., transfusion reactions, 
delayed-type hypersensitivity reaction caused by contact allergen).” 
 Removed blood sample collection for TCR analysis as this will no longer be done. 
o Section 6.1, 6.2, and 6.4.7 
 Recommendations for Initial Management of Electrolyte Imbalances and Prevention of Tumor 
Lysis Syndrome (Section 16.4) has been updated.  
 Table 4 TLS Classification was corrected and updated: 

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o Corrected value of phosphorus for hyperphosphatemia. The original version of Howard’s 
paper (N Engl J Med 2011) included incorrect values. The values here should correct to 
be consistent with the values after erratum of Howard’s paper. 
o Updated value of ionized calcium for hypocalcemia was corrected to <4.5 mg/dL (1.12 
mmol/L) in TLS classification Table 4 per ref 
(https://www.nejm.org/doi/full/10.1056/NEJMx180018?query=recirc_curatedRelated_ar
ticle) 
 A minimum 3-day stagger between dosing the first and second subject at each SL-172154 
dose level has been added.  
“…At each dose level, a minimum 3-day stagger between dosing the first and second subject 
is required.” 
o Section 3.1.1, 3.2.1 
 Revised conditions for exclusion of CAR-T therapy.  
“CAR-T cell therapy within 3 months from the first dose of the study drug.”  
o Section 4.2, Exclusion 1  
 Step-up dose schedule of SL-172154 at 6.0 or 10.0 mg/kg has been included in the following 
sections:  
o Section 3.1, Section 3.2, Section 16.10  
 Multigated Acquisition (MUGA) scans are included as an assessment method for left 
ventricular ejection fraction.
o Table 6.1, Table 6.2, Section 6.4.6  
Country-Specific Revisions:
 Edits have been incorporated to clarify that, for newly diagnosed secondary AML, 
enrollment is restricted to the subjects who are unlikely to benefit from standard intensive 
induction therapy or refuse intensive induction therapy at the time of enrollment 
o Section 4.1 (Inclusion criterion 8c)
“Subjects with newly diagnosed secondary AML and who are unlikely to benefit from standard 
intensive induction therapy or refuse intensive induction therapy at time of enrollment are 
eligible for enrollment.” 
 Clarification has been added to exclude subjects who are eligible for rescue chemotherapy 
and allogeneic-hematopoietic cell transplantation (HCT) at the time of screening.  
o Section 4.1 (Inclusion criteria 5 and 6) 
“Subjects must not be eligible for rescue chemotherapy and allogeneic-HCT per local or 
institutional guidelines at the time of screening.” 
 Exception for Covid-19 regarding use of live attenuated vaccine has been removed and 
clarification added: 
“Receipt of live attenuated vaccine within 30 days of first dose of SL-172154 treatment, the 
exception is that vaccines for COVID 19 are permitted.” 
o Section 3.7.1, Section 4.2 (exclusion criterion 7) 

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“Live attenuated vaccines during the study through 30 days after the last dose of SL-172154, the 
exception is that vaccines for COVID 19 are permitted.” 
o
Section 3.7.1 Prohibited Medications or Treatments 
“Vaccines for COVID-19 are permitted as they are not live attenuated vaccines. If administered, 
COVID-19 vaccines should not be administered on the same day as any of the study medications; 
please discuss with the Medical Monitor regarding the timing of COVID-19 vaccine 
administration during this study.” 
o Section 3.7 Concomitant Medications, Treatments and Procedures 
 Edits have been incorporated to indicate that the marketed agents azacitidine and venetoclax are 
included in this study in combination regimens under investigation.  
Section 1.7: “…Azacitidine and venetoclax are commonly used in clinical practice standard of 
care (SOC) therapies in these patient populations, with well-described safety and PK profiles 
for the individual agents and the combination. This is the first clinical trial to investigate the 
combination of these agents with SL-172154. Each component is anticipated to have activity on 
distinct targets, and these SOC agents combined with SL-172154 have the potential to further 
bridge innate and adaptive immunity, thus potentially improving treatment outcomes without 
increasing toxicity.” 
Section 3.2.2: “Azacitidine (75 mg/m2, IV or SQ on Days 1 to 7 or alternative 5-2-2 or 4-2-3
schedule) and venetoclax (target dose of 400 mg, oral, once daily) will be administered at their 
standard dose and schedule as described (Section 5.2 and Section 5.3) in 28-day cycles.”
Section 3.4: The RP2D is a dose of SL-172154 that can be safely administered with standard of 
care doses of azacitidine or azacitidine with venetoclax. 
 Reference has also been added to the current country’s prescribing information for guidance on 
use and toxicity management for azacitidine-related or venetoclax-related toxicities. 
Section 3.2.1: During therapy, management of azacitidine-related toxicity should follow the 
guidelines provided in the country’s current prescribing information (e.g., USPI, SmPC, or 
Product Monograph) current USPI or local guidelines in other countries. 
Section 3.2.2: During therapy, management of azacitidine-related or venetoclax-related toxicity 
should follow the guidelines provided in the country’s current prescribing information (e.g., 
USPI, SmPC, or Product Monograph)current USPI or local guidelines in other countries. 
 Use of “prescribing information” has been amended to “the country’s current prescribing 
information (e.g., USPI, SmPC, or Product Monograph)” in the following locations: 
 Section 3.7.1, Section 3.7.2, Section 3.9, Section 3.10, Section 5.2, Section 5.3 
 

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16.14 Summary of Changes for Protocol Amendment 3.2 
This amendment was done to address FDA’s comments on previous amendments and it applies 
to all Investigator sites participating in this study. In addition, this amendment includes added 
assessments of post-infusion hematology to evaluate hemoglobin level changes immediately 
after infusion. Text revisions resulting from this amendment are incorporated in the body of 
Protocol Amendment 3.2. 
Minor editorial changes (including protocol version number and approval date, table of contents) 
as well as minor clarification edits to text are incorporated in this amendment. 
This protocol was amended to include the following: 
In Section 3.14: Study Treatment Discontinuation Criteria. The following text was modified 
for clarification.
A subject meeting the response criteria of relapsed or progressive disease, or determination 
of clinical progression is considered a sufficient reason to discontinue study drug treatment. 
However, if the determination of progression is equivocal for a subject with AML, the 
Investigator may continue study drug treatment when a subject with transfusion 
independence at baseline remains post treatment transfusion independent or when a subject 
with transfusion dependence at baseline become post-treatment transfusion independent.  
Transfusion independence at baseline is defined as no by transfusion requirement during the 
4-week period prior to the first dose of study drug treatment.   
 Step-up dose was removed from the Protocol. Sections 3.1.1, 3.2.1 and 3.2.2 were updated 
to reflect this change. Appendix 6.10 (Step-up dose schedule of SL-172154) was removed.  
 Schedule of assessments 6.1: A post-infusion hematology sample 2 hours from the end of 
infusion was added on C1D1, C1D8, C1D15 and C2D1 for monotherapy cohorts. 
 Schedule of assessments 6.2: A post-infusion hematology sample 2 hours from the end of 
infusion was added on C1D2, C1D9, C1D16 and C2D2 for combination cohorts. A 
hematology sample prior to SL-172154 infusion was also added on C2D2 for evaluation of 
baseline counts. 
Schedule of assessment 6.1.1: C1D1 and C2D1 blood sample for receptor occupancy 
assessment was changed from 1.5hr post-EOI to 2.0hr post-EOI time point. In addition, 
C1D15 blood sample time point was changed from 1.5hr post-EOI to 2.0hr post-EOI. 
Schedule of assessment 6.2.1: C1D2 and C2D2 blood sample for receptor occupancy 
assessment was changed from 1.5hr post-EOI to 2.0hr post-EOI time point. In addition, 
C1D16 blood sample time point was changed from 1.5hr post-EOI to 2.0hr post-EOI.

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16.15 Summary of Changes for Protocol Amendment 4.0 
This amendment applies to all Investigator sites participating in this study. The purpose of this 
amendment is to update prophylactic premedication for infusion related reactions, update IRR 
management guidelines, update enrollment numbers and clarify schedule of assessments. Minor 
editorial changes as well as minor clarification edits to the text are incorporated in this 
amendment. 
Section: Study Schema
Description of change: Updated the subject numbers for Part A and Part C.
Rationale: To be consistent with the changes made in the protocol
Section: Synopsis
Description of change: Updated the synopsis with the changes made in the protocol.
Rationale: To be consistent with the body of the protocol 
 Section: Throughout the Protocol  
 Description of change: ‘patient’ was updated to ‘subject’.
 Rationale: For consistency 
 Section: Throughout the Protocol  
Description of change: Reference to Spain was removed throughout the protocol.
Rationale: The study will not be conducted in Spain due to regulatory approval challenges 
 Section: Throughout the Protocol
Description of change: Updated number of subjects to be enrolled in Part A from 
approximately 20 subjects to approximately 30 subjects and the number of subjects to be 
enrolled in Part C from approximately 10 subjects to up to 20 subjects. 
Rationale:  
Increasing 30 treatment naïve subjects with higher-risk MDS in Part A will allow enrollment
and analysis of response data for subjects with wild-type TP53 and TP53 gene 
mutation/deletion. Clinical outcomes are shown to be distinct between these patient 
populations.  
In Dose Expansion Cohort Part C, subjects with previously untreated de novo AML or 
secondary AML with TP53 gene mutation or deletion are eligible. The recent AML 
classification defines AML with mutated TP53 as disease with somatic TP53 mutation (variant 
allele frequency: Variant Allele Frequency, VAF, > 10%). Nonetheless, it is not currently 
feasible to obtain the results of VAF and further details of TP53 alterations during screening, 
which make it challenging to know how many subjects will have VAF > 10% or multi-hit TP53 
alterations. Thus, increasing the size to up to 20 subjects could provide scientifically 
meaningful interpretation by conducting VAF and further details of TP53 alterations later.  The 
enrolment of up to 20 subjects will also provide a narrow confidence interval. 

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 Section 1.6 Summary of Clinical Data 
Description of change: Updated the section with data available as of 25May2023. Updated 
the summary of data for SL03-OHD-101, a Phase 1 first-in-human study. 
Rationale: To provide updated clinical information to the investigators.  
 Section 1.8.1 Potential risks 
Description of change: Added updated data from SL03-OHD-101, a Phase 1 first-in-human 
study. 
Rationale: To provide updated clinical information to the investigators.  
Section 3.1 Description of Study Design (Table 1, Table 2); Section 6 Study assessments 
and procedures (Table 11, Table 12)
Description of change: Duration of infusion for 3 mg/kg SL-172154 was updated from 120 
minutes (± 15 minutes) to 180 minutes (± 15 minutes)
Rationale: Based on the available data from SL-172154 studies, decreasing the rate of 
infusion has been shown to help in reducing the incidence of infusion related reactions.
Section 3.7.1 Prohibited Medications or Treatments
Description of change: Corticosteroids use as prophylactic premedication was added under 
permitted exceptions.
Rationale: Dexamethasone will be given as a premedication prior to each SL-172154 
administration 
Section 3.7.3 Prophylactic Premedication for Infusion-Related Reactions (IRR) (All 
Subjects) and throughout the protocol  
Description of change: Added Dexamethasone (8 mg IV, administered at least 30 minutes 
prior to each SL-172154 administration) as a prophylactic premedication.
Rationale: The safety monitoring committee reviewed emerging data from the current study 
and recommended dexamethasone as premedication as it may reduce the IRR incidence and 
symptoms.
Description of change: changed ranitidine 50 mg PO or IV (or equivalent) to famotidine 20 
mg PO or IV (or equivalent) as an example of a histamine-2 blocker. 
Rationale: Ranitidine is no longer available.  
 Section 3.8.1 Management of Infusion Related Reactions  
Description of change: Added text to clarify that ad-hoc labs should be collected in the 
event of an IRR; clarified text for vital signs collection; updated guidance for SL-172154 
administration for subsequent cycles in the event of Grade 2 IRR.  
 Rationale: The safety monitoring committee reviewed emerging data from the current study 
and agreed with the Sponsors recommendation that SL-172154 may be administered at one 

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dose level lower, OR if the original dose is administered, the infusion must be administered 
at 50% of the rate in mg/min at which the reaction occurred. 
Section 3.8.2 Management of Cytokine Release Syndrome
Description of change: Added text to clarify that ad-hoc labs should be collected in the 
event of a CRS; clarified text for vital signs collection; deleted examples for subsequent 
infusions.
Rationale: Clarification purpose
Section 6: Study Assessments and Procedures; Appendix 16.5, Appendix 16.6
Description of change: Clarified text that if SL-172154 dose is held, then the next scheduled 
dose of azacitidine (and venetoclax) can be administered per the schedule, without any delay; 
also clarified that if the start of a subsequent cycle (e.g., Day 1) is delayed due to azacitidine-
related or venetoclax-related toxicities, SL-172154 dose should also be delayed and 
consequently, the current cycle length is extended. 
Rationale: Clarification purpose
 Section 6: Study Assessments and Procedures 6.2
Description of change: PK sample was removed from C3 onwards.  
Rationale: Based on the available data from SL-172154 studies, it was determined that these 
samples are not needed. 
Description of change: footnote was added for submission of previously collected bone 
marrow sample (if available) and collection of peripheral blood for biomarker research when 
bone marrow sample could not be collected. 
Rationale: To provide an option to assess biomarkers in case bone marrow sample could not 
be collected 
Description of change: The following footnotes were clarified.  
Footnote a: Added text to clarify that laboratory tests can be performed up to 3 days prior 
to the scheduled dose.  
Footnote h3: vital signs collection recommendation in the event of an IRR 
Footnote j: clarified that additional blood sample should be collected for ADA within 45-
90 days of the last dose of study treatment. 
Rationale: Clarification purpose 
 Section 6.5.7: Local and Central laboratory assessments 
Description of change: Updated the local clinical labs by adding the liver panel lab 
assessments under clinical chemistry labs. 
Rationale: To match the case report forms in EDC and avoid confusion  
Description of Change: Deleted ‘automated’ from WBC differential.  

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Rationale: Automated methodology may not always be used for WBC differential
 Section 6.8: Bone Marrow Assessments; 6.8.2.4 Bone Marrow Aspirate for 
Translational or Biomarker Research and Table 14
Description of change: Added text that a previously collected bone marrow sample (if 
available) should be provided or peripheral blood can be submitted if a baseline bone marrow 
sample could not be collected during screening or is inadequate for analysis. 
Changes were also made to Table 14 for providing bone marrow samples for biomarker 
research (if collected).
Rationale: When a baseline bone marrow sample is not available, archival bone marrow 
sample and or peripheral blood samples may be useful for translational or biomarker 
research.
 Section 7.8: Safety Oversight 
Description of change: Clarified the frequency of safety monitoring committee meetings 
during dose expansion. 
Rationale: Clarification purpose 
 Section 9.1.2 Dose Expansion; Section 9.2.1 Analysis Populations 
Description of change: Response Rate and 90% CI out of 30 subjects was added to Table 
18. ADA analysis population was defined in Section 9.2.1.  
Rationale: To show the 90% CI for 30 subjects in Part A. ADA analysis population was 
added for clarification. 
 Section 9.2.5 Efficacy Analysis 
Description of change: Text was added that supplementary analysis may be conducted by 
applying the IWG 2023 MDS response criteria to understand preliminary efficacy further.
Rationale: For optional analysis of efficacy data with updated MDS response criteria  
 Section 9.2.5 Research Use of Stored Human Samples, Specimens, or Specimen Data 
Description of change: Text added to clarify that subjects may choose to withdraw their 
consent at any time; however, the Sponsor will retain all data previously analyzed and will 
retain and continue to use any data or biological samples collected prior to the consent 
withdrawal, unless the subject specifically requests disposal of their samples. 
Rationale: Clarification purpose 
 Section 13.5 Future use of Stored Specimens 
Description of change: Section was deleted. 
Rationale: Samples will not be stored for future use. 

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16.16 Summary of Changes for Protocol Amendment 5.0 
This amendment was done to address FDA’s comments on amendment 4.0 and it applies to all 
Investigator sites participating in this study. Text revisions resulting from this amendment are 
incorporated in the body of Protocol Amendment 5.0. 
Minor editorial changes (including protocol version number and approval date, table of contents) 
as well as minor clarification edits to text are incorporated in this amendment.
This protocol was amended to include the following: 
Section: Study Schema
Description of change: Updated the subject numbers for Part A, added Schema for Part D
Rationale: To be consistent with the changes made in the protocol
Section: Synopsis
Description of change: Updated the synopsis with the changes made in the protocol. 
Rationale: To be consistent with the body of the protocol 
 Section: Throughout the Protocol
Description of change: Updated number of subjects to be enrolled in Part A from 
approximately 30 subjects to approximately 20 subjects. 
Rationale:  
In amendment 4.0, the number of treatment naïve subjects with higher-risk MDS in Part A was 
increased from approximately 20 subjects to approximately 30 subjects. Upon review of 
amendment 4.0, FDA informed the Sponsor that a control arm should be included when more 
than 20 subjects are enrolled in dose expansion in the study. Thus, the number of subjects in 
Part A was changed back to approximately 20 subjects. Instead, Part D was added into 
amendment 5.0 to include a control arm in which patients with HR-MDS will be treated with 
azacitidine monotherapy (the current standard of care).   
Section 1.7 Study Rationale 
Description of change: Part D design was summarized, and rationale was provided.  
Approximately 60 treatment naïve subjects with higher-risk MDS will be randomized to three 
arms (approximately 20 subjects per arm). The three arms consist of two experimental arms at 
two dose levels of SL-172154 (1.0 mg/kg and 3.0 mg/kg) in combination with azacitidine, and 
one control arm for azacitidine monotherapy. The three arms will be stratified based on TP53 
 
Rationale: Safety and efficacy will be further explored in Part D (with randomized control 
arm of azacitidine monotherapy). This will help evaluate the safety, and efficacy of different 
doses of SL-172154, and help determine the contribution of SL-172154 to the anti-leukemic 
activity in the azacitidine plus SL-172154 treatment. 
Section 2.0 Study Objectives and Outcome Measures 

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Description of change: Primary objectives were added to evaluate safety and efficacy in Part 
D, a randomized cohort with untreated higher risk MDS subjects with two doses of SL-172154
in combination with azacitidine compared to control group treated with azacitidine 
monotherapy. Part D specific secondary objective was added to assess preliminary antitumor 
activity in subjects treated with SL-172154 and azacitidine compared to azacitidine 
monotherapy. Part D specific exploratory objectives were added to assess platelet transfusion 
independence and MRD (minimal residual disease) in SL-172154 and azacitidine treated 
higher risk MDS subjects compared to azacitidine monotherapy treated subjects. Overall 
survival was moved from exploratory objectives to secondary objectives.
Rationale: Part D was added in this amendment to evaluate additional safety and efficacy of 
SL-172154 and azacitidine combination compared to azacitidine monotherapy in previously 
untreated higher risk MDS subjects. The objectives and outcomes were updated to reflect Part 
D specific aims.
Section 3.3.4 Part D (Randomized Cohorts): SL-172154 with Azacitidine vs Azacitidine 
monotherapy in HR-MDS Subjects  
Description of change: Study design was summarized. Approximately 60 treatment naïve 
subjects with higher-risk MDS will be randomized equally into three arms: 1.0 mg/kg or 3.0 
mg/kg SL-172154 in combination with azacitidine, and a control arm with azacitidine 
monotherapy. Subjects will be stratified based on TP53 mutation status (TP53m vs TP53wt) 
Rationale: Data from Part D will help evaluate the safety, and efficacy of two different doses 
of SL-172154 and help determine the contribution of SL-172154 to the anti-leukemic activity 
in the azacitidine plus SL-172154 treatment. 
Section 4.1 Inclusion Criteria, Section 4.2 Exclusion Criteria
Description of change: 
Part D specific inclusion criteria were added. Prior luspatercept was added as an allowed 
supportive care for clarification.
Rationale: To confirm that it is safe for subjects to receive SL-172154 and azacitidine 
combination treatment.
Section 6.2 (Schedule of Assessments: SL-172154 Combination Cohorts, Dose 
Escalation or Dose Expansion (SL-172154 with Azacitidine or Azacitidine and 
Venetoclax) 
Description of change: Per FDA’s request, more frequent vital sign monitoring during 
infusion and post-infusion was added in amendment 5 for every SL-172154 infusion.
Rationale: 
After reviewing amendment 4.0, FDA recommended more frequent monitoring of vital signs 
during each SL-172154 infusion. 

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Section 6.2 Schedule of Assessments: SL-172154 Combination Cohorts, Dose Escalation 
or Dose Expansion (SL-172154 with Azacitidine or Azacitidine and Venetoclax); Section 
6.6.1 Physical Examination 
Description of change:  
Added physical examination for PTV visit.
Added a footnote to clarify that full physical exam is required only at screening and 
PTV. On-treatment physical exams should be performed per standard of care. 
Wording in Section 6.6.1 was also clarified.
Rationale: 
 Full physical examination during PTV was added for complete safety assessment. Full 
physical examination during PTV was also included in Part D. 
 The wording in Section 6.6.1 was unclear. Added text for clarification.  
 
Schedule of Assessments: Section 6.3 [Dose Expansion Cohort Part D (SL-172154 in 
Combination with Azacitidine in Previously Untreated HR-MDS Subjects)]; Section 
6.3.1 [PK, ADA, Receptor Occupancy, Complement Analysis and Cytokines Sampling 
Schedule for Dose Expansion Cohort Part D (SL-172154 in Combination with 
Azacitidine in Previously Untreated HR-MDS Subjects)]; Section 6.4 [Dose Expansion 
Cohort Part D (Azacitidine monotherapy in Previously Untreated HR-MDS Subjects)]; 
Section 6.4.1 [Immunophenotyping, Complement Analysis and Cytokines Sampling 
Schedule for Dose Expansion Cohort Part D (Azacitidine Monotherapy in Previously 
Untreated HR-MDS Subjects) 
Description of change:  
 Schedules for assessments including safety monitoring, efficacy and administration of 
study drugs are provided for Part D arms.  
 Sample collection schedules for assessing PK, ADA, cytokines, complement analysis 
and receptor occupancy/immunophenotyping are provided.  
Rationale:  
Data from Part D will help evaluate the safety, and efficacy of two different doses of SL-
172154 and help determine the contribution of SL-172154 to the anti-leukemic activity in the 
azacitidine plus SL-172154 treatment.  
Identification of a potential biomarker that may support the mechanism of action or the 
pharmacology of the SL-172154 blood samples will be collected in Part D which includes SL-
172154+ azacitidine combination arms and a randomized controlled group with the azacitidine 
alone. Samples in the azacitidine alone group will be collected at the minimum timepoints 
required for comparison with the combination arms. 
Section 6.5.7 Randomization  
Description of change: Randomization process was summarized. 

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Rationale: Using the Randomization and Trial Supply Management system, subjects will be 
randomized equally into three arms: 1.0 mg/kg or 3.0 mg/kg SL-172154 in combination with 
azacitidine, and a control arm with azacitidine monotherapy. 
Section 6.6.7 Local and Central Laboratory Assessments, Section 6.6.7.1 Ad Hoc Labs 
for IRR or CRS AEs 
Description of change: Ferritin and C-Reactive Protein samples were added for screening 
visit and ad hoc labs. 
Rationale: Screening sample will serve as baseline sample in case of an infusion related 
reaction (IRR) or cytokine release syndrome (CRS). Ad hoc labs are collected to assess safety 
in case of an IRR or CRS.
Section 6.9 Pharmacodynamic assessments in blood
Description of change: Section was updated with the description of pharmacodynamic 
markers included in Part D.
Rationale: Identification of a potential biomarker that may support the mechanism of action 
or the pharmacology of the SL-172154 blood samples will be collected in Part D which 
includes SL-172154+ azacitidine combination arms and a randomized controlled group with 
the azacitidine alone. 
Section 6.10 Table 17 Bone Marrow Assessment Schedule for SL-172154 in Combination 
with Azacitidine or Azacitidine Monotherapy Treatment (Dose Expansion cohort Part 
D)
Description of change: Bone marrow sample collection schedule for disease assessment and 
biomarker analysis has been added. 
Rationale: Specified sample collection schedule 
Section 7.1.1 Events not qualifying as AE or SAE
Description of change: Deaths that are clearly determined to be due to disease progression 
should not be reported as AEs/SAEs.
Rationale: Clarification purpose
Section 9 Data Analysis and Statistical Considerations: Section 9.1.2 Dose Expansion, 
Section 9.1.3 Sample Size Determination
Description of change: 
Revised the text and Tables to reflect changing of number of subjects in Part A to 
approximately 20 (from approximately 30 in amendment 4.0)
Added Statistical assumptions and considerations for sample sizes in Part D arms
Rationale: Description of statistical analysis plan for Part D
Section 9.2.1 Analysis Populations; 9.2.4 Safety Analyses; Section 9.2.5 Efficacy Analyses
Description of change: 
Intent to treat population for Part D was defined.

CONFIDENTIAL 
SL03-OHD-104
Compound: SL-172154 
Version no: 5.0
Page 200 of 200
 Safety and efficacy analyses Sections were updated with analyses plans for Part D.
Rationale: Described populations to be analyzed in Part D and added safety and efficacy 
analyses plans for Part D.