Study of APR-246 in Combination With Pembrolizumab in Subjects With Solid Tumor Malignancies
Phase: PHASE1
Conditions: Bladder Cancer, Gastric Cancer, Non Small Cell Lung Cancer, NSCLC, Urothelial Carcinoma, Advanced Solid Tumor
Sponsor: Aprea Therapeutics

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CLINICAL STUDY PROTOCOL 
 
Phase 1/2 study of APR-246 in Combination with Pembrolizumab in Subjects with 
Solid Tumor Malignancies 
 
Protocol No.: 
A20-11195  
 
IND No.: 
124841 
 
 
 
 
 
Sponsor: 
Aprea Therapeutics, Inc. 
 
 
 
 
 
 
 
Responsible Medical Officer: 
Eyal C. Attar, M.D. 
 
 
Medical Monitor: 
 
 
 
 
 
 
Protocol Version: 
1.0 
 
Replaces: 
 
n/a 
Date: 
13 March 2020 
 
 
 
 
 
 
 
 
CONFIDENTIAL 
 
This document contains strictly confidential information and cannot be disclosed or used, 
unless authorized in writing by Aprea Therapeutics. 
 

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Name: 
 
 
Telephone: 
 
 
 
 
 
 
Address: 
 
 
 
 
 
 
 
 
 
Signature: 
 
 
Date: 
 
 
Sponsor/Representative: 
 
Signature: 
 
 
Date: 
 
 
 
 
INVESTIGATOR’S STATEMENT 
1. 
I have carefully read this protocol entitled “Phase 1/2 Study of APR-246 in Combination 
with Pembrolizumab in Subjects with Solid Tumor Malignancies” and agree that it contains 
all the necessary information required to conduct the study. I agree to conduct this study 
as outlined in the protocol. 
2. 
I understand that this study will not be initiated without approval of the appropriate 
Institutional Review Board/Independent Ethics Committee (IRB/IEC), and that all 
administrative requirements of the governing body of the Institution will be complied with 
fully. 
3. 
Informed written consent will be obtained from all participants in accordance with 
institutional guidelines, Food and Drug Administration (FDA) requirements as specified in 
Title 21 Code of Federal Regulations, Part 50, the European Union Directive 
2001/20/European Commission (EC) and its associated Detailed Guidances, European 
Union Good Clinical Practice (GCP) Directive 2005/28/EC, the International Council for 
Harmonisation (ICH) Guideline for GCP, Section 4.8, and the terms of the Declaration of 
Helsinki (2013). 
4. 
I will enroll participants who meet the protocol criteria for entry. 
5. 
I understand that my signature on each completed electronic Case Report Form (eCRF) 
indicates that I have carefully reviewed the complete set of eCRFs and accept full 
responsibility for the contents thereof. 
6. 
I understand that the information presented in this study protocol is confidential, and I 
hereby assure that no information based on the conduct of the study will be released 
without prior consent from the Sponsor unless this requirement is superseded by the FDA, 
a Competent Authority of the European Union or another Regulatory Authority. 
 
Protocol Version 1.0: 13 March 2020 

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TABLE OF CONTENTS 
 
        Page No. 
 
INVESTIGATOR’S STATEMENT .................................................................................................. 2 
TABLE OF CONTENTS ............................................................................................................... 3 
CLINICAL STUDY SYNOPSIS ..................................................................................................... 7 
LIST OF ABBREVIATIONS ........................................................................................................ 18 
1.0 
GENERAL INFORMATION ......................................................................................... 21 
1.1 Protocol Number and Title of the Study .................................................................... 21 
1.2 Sponsor ........................................................................................................................ 21 
1.3 Monitor ......................................................................................................................... 21 
1.4 Signature Authorization .............................................................................................. 21 
2.0 
BACKGROUND INFORMATION ................................................................................ 22 
2.1 APR-246 ........................................................................................................................ 22 
2.2 APR-246 Preclinical Studies......................................................................................... 22 
2.2.1 Pharmacology and Mode of Action ............................................................... 22 
2.2.2 Safety Pharmacology ...................................................................................... 23 
2.2.3 Pharmacokinetics and Metabolism in Animals ............................................. 24 
2.2.4 Toxicology ........................................................................................................ 24 
2.3 APR-246 Clinical Studies .............................................................................................. 25 
2.3.1 Phase 1/2 Study in Solid and Hematological Malignancies ......................... 25 
2.3.2 Phase 1/1b Study in Refractory Hematologic Malignancies ........................ 26 
2.3.3 Phase 1/2 Study in TP53-Mutant Advanced Ovarian Cancer ....................... 26 
2.3.4 Phase 1b/2 Study in TP53-Mutant Myeloid Neoplasms ............................... 27 
2.3.5 APR-246 CNS Safety Overview........................................................................ 27 
2.3.6 APR-246 Cardiac Safety Overview .................................................................. 27 
2.4 Pembrolizumab ........................................................................................................... 28 
2.5 Rationale for Combination of APR-246 in with Pembrolizumab ............................. 29 
2.6 Rationale for Dose and Schedule of APR-246 in Combination with Pembrolizumab
 
31 
2.7 Potential Risks and Benefits ....................................................................................... 31 
2.7.1 Potential Risks ................................................................................................. 31 
2.7.2 Potential Benefits ............................................................................................ 32 
2.8 Characteristics of a Well-Conducted Trial .................................................................. 32 
2.9 Subject Population ...................................................................................................... 33 
3.0 
TRIAL OBJECTIVES AND PURPOSE ........................................................................... 33 
3.1 Primary objective: ........................................................................................................ 33 
3.2 Secondary objectives: .................................................................................................. 33 
3.3 Exploratory objectives: ................................................................................................ 33 

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4.0 
TRIAL DESIGN ............................................................................................................ 34 
4.1 Overview of Trial Design ............................................................................................. 34 
4.2 End of Study ................................................................................................................. 35 
4.3 Drug Products .............................................................................................................. 35 
4.3.1 APR-246 ............................................................................................................ 35 
4.3.2 Pembrolizumab ............................................................................................... 36 
4.4 Duration of Therapy .................................................................................................... 36 
4.5 Trial Discontinuation ................................................................................................... 36 
4.6 Drug Accountability/Disposition of Clinical Trial Supplies ....................................... 36 
4.7 Registration .................................................................................................................. 37 
5.0 
SELECTION AND WITHDRAWAL OF SUBJECTS ........................................................ 38 
5.1 Inclusion Criteria: ......................................................................................................... 38 
5.2 Exclusion Criteria ......................................................................................................... 39 
5.3 Inclusion of Women, Minorities and Children ........................................................... 40 
5.4 Withdrawal Criteria ...................................................................................................... 40 
5.4.1 Study Treatment Discontinuation .................................................................. 40 
5.4.2 Study Discontinuation ..................................................................................... 40 
5.4.3 Withdrawn Subjects ........................................................................................ 41 
5.5 Noncompliance ............................................................................................................ 41 
6.0 
TREATMENT OF SUBJECTS ........................................................................................ 41 
6.1 Drug Preparation and Administration ....................................................................... 41 
6.1.1 Dose-Limiting Toxicity ..................................................................................... 42 
6.1.2 Recommended Phase 2 Dose (RP2D) ............................................................ 43 
6.2 Dose Interruptions/Withholding ................................................................................ 44 
6.3 Supportive Management ............................................................................................ 44 
6.3.1 Cardiac Monitoring.......................................................................................... 44 
6.3.2 Management of CNS Adverse Events ............................................................ 45 
6.3.3 Management of Nausea and Vomiting.......................................................... 46 
6.3.4 Management of Infusion Reactions ............................................................... 47 
6.4 Concomitant Treatment .............................................................................................. 48 
6.5 Monitoring Subject Compliance ................................................................................. 48 
7.0 
STUDY EVALUATIONS ............................................................................................... 48 
7.1 Schedule of Study Evaluations ................................................................................... 48 
7.1.1 Screening ......................................................................................................... 52 
7.2 Pre-Study Assessments ............................................................................................... 52 
7.2.1 Cycle 1 .............................................................................................................. 53 
7.2.2 Cycle 2 and Onwards (Cycle 3+) Day 1 (±3 Days) .......................................... 53 
7.3 End of Treatment Visit ................................................................................................. 54 
7.4 Long-Term Follow-Up .................................................................................................. 55 
8.0 
STUDY ASSESSMENTS ............................................................................................... 55 
8.1 Safety Assessments ..................................................................................................... 55 

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8.1.1 Safety Analysis ................................................................................................. 55 
8.1.2 Reporting of Adverse Events .......................................................................... 55 
8.2 Efficacy Assessments ................................................................................................... 59 
8.2.1 Objective Response Rate ................................................................................ 60 
8.2.2 Disease Control Rate ....................................................................................... 61 
8.2.3 Duration of Response ..................................................................................... 61 
8.2.4 Durable Stable Disease Rate .......................................................................... 61 
8.2.5 Clinical Benefit Rate ........................................................................................ 61 
8.3 Progression-Free Survival (PFS) .................................................................................. 61 
8.4 Overall Survival ............................................................................................................ 61 
8.5 Pharmacokinetics ........................................................................................................ 61 
8.6 Electrocardiographic Assessment .............................................................................. 62 
8.7 Correlative Studies ...................................................................................................... 62 
9.0 
STATISTICS ................................................................................................................. 63 
9.1 Sample Size .................................................................................................................. 63 
9.2 Analysis Populations ................................................................................................... 64 
9.3 Data Summaries .......................................................................................................... 64 
9.4 Pharmacokinetic Analysis ........................................................................................... 65 
10.0 
QUALITY CONTROL AND QUALITY ASSURANCE PROCEDURES ............................ 66 
10.1 Monitoring of the Study and Regulatory Compliance .............................................. 66 
10.2 Curricula Vitae and Financial Disclosure of Investigators ........................................ 66 
10.3 Protocol Modifications ................................................................................................ 66 
10.4 Publication Policy ......................................................................................................... 66 
11.0 
ETHICAL CONSIDERATIONS ..................................................................................... 67 
11.1 Informed Consent ....................................................................................................... 67 
11.2 Institutional Review Board/Independent Ethics Committee .................................... 67 
11.3 Subject Privacy ............................................................................................................. 67 
12.0 
DATA HANDLING AND RECORD KEEPING .............................................................. 67 
12.1 Data to be Entered Directly in the electronic Case Report Form ............................ 67 
12.2 Recording of Data ........................................................................................................ 68 
12.3 Study Records .............................................................................................................. 68 
13.0 
REFERENCES .............................................................................................................. 69 
APPENDIX I - Cockcroft-Gault Equation .............................................................................. 71 
APPENDIX II - ECOG Performance Status ............................................................................ 72 
APPENDIX III - Acceptable Contraceptive Methods ........................................................... 73 
APPENDIX IV - New York Heart Association (NYHA) Classification ................................. 75 
APPENDIX V - Tumor Measurement Based on RECIST 1.1 ................................................. 76 
 
 

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List of In-text Tables 
Table 1. APR-246 Dose Levels ..................................................................................................... 35 
Table 2. Management of CNS Adverse Events (Dizziness, Dyskinesia and Ataxia) ................ 46 
Table 3. Medications for Managements of Nausea and Vomiting .......................................... 47 
Table 4. Study Calendar .............................................................................................................. 49 
Table 5. PK Blood Sampling Timepoints for APR-246 in Cycle 1 and Cycle 3 ......................... 61 
Table 6. ECG Assessment Requirements ................................................................................... 62 
Table 7. 2-sided 95% Confidence Interval for the ORR of 20% and 30% (20, 30 and 40 
sample sizes) ................................................................................................................................ 63 
 
List of In-text Figures 
Figure 1. Clinical Trial Schema ...................................................................................................... 7 
Figure 2. APR-246 Dose-Finding Study Design ............................................................................ 8 
Figure 3. Structure of APR-246 ................................................................................................... 22 
Figure 4. APR-246 enhances effects of PD-1 blockade in melanoma and colorectal 
carcinoma models ....................................................................................................................... 30 
 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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CLINICAL STUDY SYNOPSIS 
Title 
Phase 1/2 Study of APR-246 in Combination with Pembrolizumab in Subjects with 
Solid Tumor Malignancies 
Sponsor 
Aprea Therapeutics, Inc. 
Monitor/ 
Contract 
Research 
Organization 
(CRO) 
 
Number of 
Study Centers 
Multicenter 
Clinical Phase 
1/2 
Sample Size 
Up to 18 subjects in safety lead-in portion, up to 100 subjects in phase 2 expansion 
portion 
Investigational 
Agent 
APR-246 
Study Design 
This clinical trial is a phase 1/2, open-label, study to determine the safety and 
preliminary efficacy of APR-246 in combination with pembrolizumab in subjects with 
solid tumor malignancies. The study will include a safety lead-in portion followed by 
a phase 2 expansion portion in specific disease groups (Figure 1). 
 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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Figure 1. Clinical Trial Schema 
During the safety lead-in portion of the study, subjects with advanced solid tumor 
malignancies will receive pembrolizumab in combination with APR-246, as outlined 
in 
 
Figure 2.  
 
 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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Figure 2. APR-246 Dose-Finding Study Design  
 
Dosing will begin at the full dose of both drugs due to the well-established safety 
profiles of APR-246 and pembrolizumab, the non-overlapping mechanisms of action, 
and the desire to treat patients at doses shown to be effective in previous studies. 
Lower dose levels of APR-246 will be explored as necessary depending on observed 
toxicity. 
 
The initial cohort of subjects will receive APR-246 at 4.5 g/day administered as an 
intravenous (IV) infusion on Days 1–4 in combination with pembrolizumab at the 
approved dose of 200 mg on Day 3 of each 21-day cycle. This cohort will enroll up to 
a maximum of 6 subjects. Dose-limiting toxicity (DLT) will be assessed after three 
subjects have been enrolled in each respective cohort and the last enrolled subject 
has completed the 3-week safety assessment period (i.e., one cycle of combination 
regimen). A subject that discontinues therapy during Cycle 1 without DLT is 
considered evaluable for the purpose of safety only if at least 75% of scheduled 
doses of APR-246 were administered in the first cycle. At the first dose level of 
4.5 g/day of APR-246, if ≤ 1 subject out of 3 experiences a DLT, 3 additional subjects 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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will be enrolled. If ≤ 1 subject out of 6 experiences DLT, the dose level (4.5 g/day of 
APR-246) will be deemed the recommended phase 2 dose (RP2D) for that cohort. If 
≥ 2 subjects out of the total 3 – 6 subjects in the cohort experience DLT, the study will 
continue enrollment at Dose Level -1 (4.0 g/day of APR-246). If ≤ 1 subject out of 6 
experiences DLT at this dose level, the dose level (4.0 g/day of APR-246) will be 
deemed the RP2D for that cohort. If ≥ 2 subjects out of the total 3 – 6 subjects at that 
dose level experience DLT, the study will continue enrollment at Dose Level -2 
(3.5 g/day of APR-246). If ≤ 1 subject out of 6 experiences DLT at this dose level, the 
dose level (3.5 g/day of APR-246) will be deemed the RP2D for that cohort. If ≥ 2 
subjects out of the total 3 – 6 subjects at this dose level experience DLT, the trial will 
be halted and the Data Review Team (DRT) will consider potential future dosing 
modifications. No dose reductions in pembrolizumab are planned. 
 
The phase 2 portion will begin once the RP2D of APR-246 in combination with 
pembrolizumab has been determined and will assess the anti-tumor activity of this 
combination. Up to 100 subjects will be enrolled in three cohorts according to their 
underlying disease, as outlined in Figure 1. 
 
Study 
Objectives 
Primary objectives:   
1. To evaluate the safety and tolerability of APR-246 in combination with 
pembrolizumab in subjects with solid tumors. 
2. To determine and confirm the maximum tolerated dose (MTD) for APR-246 in 
combination with 200 mg IV, every 3 weeks (Q3W) pembrolizumab in subjects 
with solid tumor malignancies. 
 
Secondary objectives: 
1. Overall response rate (ORR) (Complete Response [CR] + Partial Response [PR]) of 
APR-246 in combination with pembrolizumab in subjects with solid tumor 
malignancies by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. 
2. Progression-free survival (PFS) by RECIST 1.1. 
3. Overall survival (OS). 
4. Duration of response (DOR) by RECIST 1.1. 
5. Disease control rate (DCR: CR + PR + stable disease [SD]) by RECIST 1.1 
6. Durable SD rate (durable SD [SD ≥23 weeks]) by RECIST 1.1 
7. Clinical benefit rate (CBR: CR, PR + durable SD) by RECIST 1.1. 
8. The pharmacokinetic (PK) profile of APR-246 during combination treatment with 
pembrolizumab. 
 
Exploratory objectives: 
1. To investigate the relationship between candidate efficacy biomarkers and anti-
tumor activity of APR-246 in combination with pembrolizumab based on analyses 
of blood, serum, and/or tumor tissue. 
Study 
Endpoints 
Primary endpoints: 
1. Occurrence of DLTs, classified and graded according to the National Cancer 
Institute’s Common Terminology Criteria for Adverse Events (NCI-CTCAE, version 
5.0). 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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2. Frequency of treatment-emergent adverse events (TEAEs), and serious adverse 
events (SAEs) related to APR-246 in combination with pembrolizumab. 
3. RP2D of APR-246, defined as the dose of APR-246 at which < 2 out of 6 subjects 
experience DLT during the 3-week safety assessment period after the start of 
APR-246 administration in combination with pembrolizumab using dose 
de-escalation of APR-246. 
 
Secondary endpoints: 
1. ORR, defined as the proportion of subjects who have BOR of CR or PR measured 
by RECIST 1.1 (see APPENDIX V). ORR is measured from the start date of the 
treatment period until date of death from any cause. Subjects who are lost to 
follow-up and the subjects who are alive at the date of data cutoff will be 
censored at the date the subject was last known alive. 
2. PFS, defined as the time from the first study dose date to the date of first 
documentation of confirmed disease progression or death (whichever occurs 
first). 
3. OS, measured from the date of initiating study treatment to the date of death.  
4. DOR, defined as the duration of CR or PR. 
5. DCR, defined as the proportion of subjects who have BOR of CR or PR or SD 
(duration of SD ≥ 5 weeks). 
6. Durable SD rate, defined as the proportion of subjects whose BOR is SD and the 
duration of SD is ≥ 23weeks. 
7. CBR, defined as the proportion of subjects who have BOR of CR or PR or durable 
SD (duration of SD ≥ 23 weeks). 
8. PK parameters: maximum concentration (Cmax), area under curve (AUC), volume 
of distribution (Vd) and clearance (CL) of APR-246 when administered 
concurrently with pembrolizumab. 
 
Exploratory endpoints: 
Exploratory molecular analyses may include but are not limited to: gene mutations 
by next generation sequencing (NGS, including TP53), mRNA expression, multiplex 
immunohistochemistry and transcriptomics in frozen biopsies before and on 
therapy, multiplex flow cytometry on peripheral blood mononuclear cells (PBMCs) 
and multiplex cytokines in serum.  
 
Analysis Sets: 
Safety Analysis Set will include all subjects who receive any amount of study drug. This 
will be the analysis set for all safety evaluations. 
 
MTD Analysis Set will include all subjects who complete Cycle 1 of treatment in the 
safety lead-in portion of the study or discontinue early due to DLT. This will be the 
analysis set to determine MTD. 
 
PK Analysis Set: All the subjects who receive at least 1 dose of APR-246 and have 
evaluable concentration data. 
 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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Pharmacodynamic Analysis Set will include all subjects who receive at least 1 dose of 
study drug (APR-246 or pembrolizumab) and have evaluable pharmacodynamic data. 
 
PK/Pharmacodynamic Analysis Set: All the subjects who receive at least 1 dose of study 
drug (APR-246 or pembrolizumab) and have evaluable pharmacodynamic and 
concentration data. 
Eligibility 
Criteria 
Inclusion Criteria: 
1. Signed informed consent form (ICF) and ability to comply with protocol 
requirements. 
2. Known tumor TP53 mutation status from recent or archival sample. 
3. Histologically and/or cytologically confirmed solid tumor malignancy:  
a. Safety lead-in portion:  
i. 
Patients with histologically and/or cytologically confirmed 
diagnosis of advanced non-central nervous system (CNS) 
primary tumors that have progressed after first line 
treatment, who are intolerant to first line treatment, or 
who are unable to receive first line treatment, and for 
whom pembrolizumab, or pembrolizumab-based therapy, 
is considered appropriate in the opinion of the 
investigator. Primary CNS tumors are excluded. Patients 
with clinically stable, known metastatic tumors to the CNS 
are eligible. CNS radiography is not required in the 
absence of suspicion for clinical involvement. 
b. Phase 2 Expansion portion:  
i. 
Patients with histologically and/or cytologically confirmed 
diagnosis of advanced gastric or gastroesophageal 
junction (GEJ) tumors that have progressed after first line 
treatment, who are intolerant to first line treatment, or 
who are unable to receive first line treatment. Patients 
with clinically stable, known metastatic tumors to the CNS 
are eligible with Medical Monitor approval. CNS 
radiography is not required in the absence of suspicion 
for clinical involvement. Prior treatment with anti-PD-
1/anti-PD-L1 therapy is prohibited. 
ii. 
Patients with histologically and/or cytologically confirmed 
diagnosis of advanced bladder/urothelial tumors that 
have progressed after first line treatment, or who are 
intolerant to first line treatment, or who are unable to 
receive first line treatment with cisplatin-based 
chemotherapy. Patients with clinically stable, known 
metastatic tumors to the CNS are eligible with Medical 
Monitor approval. CNS radiography is not required in the 
absence of suspicion for clinical involvement. Prior 
treatment with anti-PD-1/anti-PD-L1 therapy is prohibited. 
iii. 
Patients with histologically and/or cytologically confirmed 
diagnosis of advanced non-small cell lung cancer (NSCLC) 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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previously treated with anti-PD-1 or anti-PD-L1 therapy. 
Patients with clinically stable, known metastatic tumors to 
the CNS are eligible with Medical Monitor approval. CNS 
radiography is not required in the absence of suspicion 
for clinical involvement. 
4. Adequate organ function as defined by the following laboratory values: 
a. Creatinine clearance > 30 mL/min (by Cockcroft-Gault method, 
APPENDIX I), 
b. Total serum bilirubin < 1.5 × upper limit of normal (ULN) unless due to 
Gilbert’s syndrome, tumor involvement, hemolysis or considered an 
effect of regular blood transfusions, 
c. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) 
< 3 × ULN, unless due to involvement by the underlying malignancy. 
5. Age ≥ 18 years at the time of signing the ICF. 
6. Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2 
(APPENDIX II). 
7. Projected life expectancy of ≥ 12 weeks. 
8. In the expansion portion, measurable disease meeting the following criteria: 
a. At least 1 lesion of ≥10 mm in the longest diameter (LD) for a non-lymph 
node or ≥15 mm in the short-axis diameter for a lymph node that is 
serially measurable according to RECIST 1.1. 
b. Lesions that have had external beam radiotherapy or loco-regional 
therapies such as radiofrequency ablation must show subsequent 
evidence of substantial size increase (ex. 20% increase in LD) to be 
deemed a target lesion. 
9. Negative serum or urine pregnancy test prior to study treatment initiation in 
female subjects of childbearing potential. 
10. Women of childbearing potential and men with female partners of 
childbearing potential must be willing to use an effective form of 
contraception such as latex condom, hormonal birth control, intrauterine 
device or double barrier method (APPENDIX III) during chemotherapy 
treatment and for at least six months thereafter. 
 
Exclusion Criteria: 
1. Known history of untreated human immunodeficiency virus (HIV)/HIV with a 
detectable viral load or active hepatitis B or active hepatitis C infection. 
2. Any of the following cardiac abnormalities: 
a. Myocardial infarction within six months prior to registration; 
b. New York Heart Association Class III or IV (APPENDIX IV) heart failure or 
known left ventricular ejection fraction (LVEF) < 40%; 
c. A history of familial long QT syndrome; 
d. Symptomatic atrial or ventricular arrhythmias not controlled by 
medications; 
e. QTcF ≥ 470 msec, unless due to underlying bundle branch block and/or 
pacemaker and with approval of the Medical Monitor. 
3. Concomitant malignancies or previous malignancies with less than a 1-year 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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disease-free interval at the time of signing consent. Subjects with 
adequately treated basal or squamous cell carcinoma of the skin, or 
adequately treated carcinoma in situ (e.g. cervix) may enroll irrespective of 
the time of diagnosis. Patients with controlled, advanced prostate cancer 
are permitted. 
4. Pregnancy or lactation. 
5. Active uncontrolled systemic infection. 
6. An autoimmune condition requiring ≥ 10 mg (or equivalent corticosteroid) 
prednisone daily, or any other systemic immunosuppressive treatment 
within 28 days of first dose of study therapy. 
7. Known history of active tuberculosis. 
8. Current (non-infectious) pneumonitis, or a history of pneumonitis that 
required steroids. 
9. A live vaccine administered within 30 days of the first dose of study 
treatment. 
10. Receipt of any investigational product within 14 days or 5 half-lives prior to 
study treatment initiation, whichever is shortest. 
11. Prior intolerance to pembrolizumab or other anti-PD-1/PD-L1 agents. 
Treatment 
Plan 
This is a phase 1/2, open-label, safety and cohort expansion study to determine the 
safety and preliminary efficacy of APR-246 in combination with anti-PD1 monoclonal 
antibody (mAb) pembrolizumab in subjects with solid tumor malignancies including 
gastric/GEJ cancer, bladder/urothelial cancer, and NSCLC. The study will include a 
safety lead-in portion comprised of subjects with advanced non-CNS-primary solid 
tumors, followed by an expansion portion with separate cohorts for subjects with 
gastric/GEJ cancer, urothelial cancer and NSCLC.  
 
The safety lead-in portion of the study will follow a 3+3 dose de-escalation design. 
APR-246 will be given as a 6 h IV infusion once daily on Days 1–4 in 21-day cycles, with 
pembrolizumab administered as a 30-minute IV infusion at a standard dose of 
200 mg on Day 3 before the Day 3 infusion of APR-246. Each cohort will consist of 3-6 
subjects. The RP2D of APR-246 is the dose at which ≤ 1 of 6 subjects in a cohort has 
a DLT. Given the minimal overlap of adverse events (AEs) between APR-246 and 
pembrolizumab, and the absence of presumed drug-drug interactions (DDIs) based 
on disparate metabolism, the initial starting dose of APR-246 is 4.5 g/day. A Dose 
Level -1 cohort will use APR-246 at 4.0 g/day and a Dose Level -2 cohort will use APR-
246 at 3.5 g/day. No reduction in pembrolizumab dose is planned. 
 
A DRT consisting of the Medical Monitor, Site Principal Investigators, and other 
clinical research personnel that the Sponsor may deem appropriate, will hold Data 
Review Meetings (DRMs) on an interim basis at a frequency dependent on study 
accrual. At these meetings, the DRT will review AEs and DLTs and make 
recommendations regarding the RP2D. In the expansion portion of the study, the 
DRT will evaluate safety and tolerability after 5 subjects have completed 1 cycle of 
treatment in each cohort. All accumulated safety data will be discussed during DRMs. 
 
The expansion portion will begin once the RP2D of APR-246 in combination with 
pembrolizumab has been determined. 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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Subjects will be enrolled and stratified into one of three cohorts:  
 
• 
Patients with histologically and/or cytologically confirmed diagnosis of 
advanced gastric or GEJ tumors that have progressed after first line 
treatment, who are intolerant to first line treatment, or who are unable to 
receive first line treatment. Patients with clinically stable, known metastatic 
tumors to the CNS are eligible with Medical Monitor approval. CNS 
radiography is not required in the absence of suspicion for clinical 
involvement. Prior treatment with anti-PD-1/anti-PD-L1 therapy is 
prohibited. 
• 
Patients with histologically and/or cytologically confirmed diagnosis of 
advanced bladder/urothelial tumors that have progressed after first line 
treatment, or who are intolerant to first line treatment, or who are unable 
to receive first line treatment with cisplatin-based chemotherapy. Patients 
with clinically stable, known metastatic tumors to the CNS are eligible with 
Medical Monitor approval. CNS radiography is not required in the absence 
of suspicion for clinical involvement. Prior treatment with anti-PD-1/anti-PD-
L1 therapy is prohibited is prohibited. 
• 
Patients with histologically and/or cytologically confirmed diagnosis of 
advanced NSCLC previously treated with anti-PD-1 or anti-PD-L1 therapy. 
Patients with clinically stable, known metastatic tumors to the CNS are 
eligible with Medical Monitor approval. CNS radiography is not required in 
the absence of suspicion for clinical involvement. 
 
Duration of 
Follow-Up  
 
Subjects will be followed as per the Study Calendar. After a subject is removed or 
withdrawn from study treatment, the subject will be followed for up to 1 year or until 
death, whichever occurs first.  
Off-treatment data on OS will be updated every 6 months or until death, whichever 
occurs first. If a subject is removed from the study due to unacceptable AEs, the 
event(s) will be followed until resolution or stabilization of the AE(s). Subjects who 
respond and discontinue study treatment for reasons other than progressive disease 
(PD) should have response assessments and survival should be collected every 2 
months until disease progression or death, whichever occurs first. After disease 
progression, data for survival should be collected every 6 months until death. 
Criteria for Removal from Study Treatment 
Study treatment can continue for subjects receiving clinical benefit, unless one or 
more withdrawal criteria are met, or at the subject’s discretion, or if the study is 
terminated.  
1. Study Treatment Discontinuation 
Study treatment must be discontinued if: 
• 
There is evidence of disease progression. Subjects who have PD but who are 
continuing to derive clinical benefit in the opinion of the investigator may 
continue to receive study treatment. 

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Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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• 
A subject becomes pregnant. 
• 
A subject is significantly non-compliant with the requirements of the 
protocol.  
• 
A subject has an adverse experience that would, in the investigator’s 
judgment, make continued participation in the study an unacceptable risk. 
• 
The subject starts new treatment for their underlying disease. 
2. Subject Withdrawal from Study Treatment 
If the subject is permanently withdrawn from study treatment, but does not 
withdraw consent from the study, the investigator must make every effort to have 
the subject complete all withdrawal assessments at the time of withdrawal and 
complete all scheduled follow-up visits. 
3. Study Completion 
Subject must be taken off the study if: 
• 
The subject dies during the study. 
• 
The subject is lost to follow-up. 
• 
The subject withdraws consent. 
4. Subject Withdrawal from Study 
A subject may voluntarily withdraw from study treatment or withdraw consent from 
the study at any time. The investigator may also, at his or her discretion, discontinue 
a subject from participating in the study treatment at any time. The investigator 
and/or designated staff will record the date and the reason for subject withdrawal 
from the study. 
Statistics 
This is a phase 1/2, open-label, safety and efficacy study to determine the safety and 
preliminary efficacy of APR-246 in combination with pembrolizumab in subjects with 
solid tumor malignancies.  
In the safety lead-in part of study (phase 1), the safety and the RP2D of APR-246 will 
be investigated. The RP2D of APR-246 will be defined as the dose at which < 2 out of 
6 subjects experience DLT during the 3-week safety assessment period after the start 
of APR-246 administration in combination with pembrolizumab using dose de-
escalation of APR-246. 
In the expansion part of the study (phase 2), the combination therapy at the RP2D 
will be given to patients in the 3 cohorts. Both safety and efficacy will be further 
investigated.  
Determination of Sample Size 
In the safety lead-in portion of the study, up to 18 DLT-evaluable patients will be 
enrolled to determine RP2D. 
The dose expansion consists of 3 cohorts. The ORRs to pembrolizumab for the 
patients with the 3 types of cancer, who were relapsed/refractory R/R to previous 
chemotherapies, were 21.1% and 22,7% for urothelial cancer and gastric/GEJ 
adenocarcinoma, respectively. The ORR for patients with advanced NSCLC who have 
previously been treated with anti-PD-1/PD-L1 therapy is expected to be negligible 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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(i.e. <= 20%). As such, the expected response rate to the combination therapy across 
indications is 20% to 30%.  In order to increase the estimate precision, at least 20 
evaluable patients will be included in each of the 3 cohorts. 
Analysis Populations 
Safety population: Subjects will be evaluable for safety if they receive at least one 
dose of APR-246. The safety population will be used to summarize exposure and 
safety parameters. 
DLT-evaluable population: In the safety lead-in portion of the study, subjects who 
either experience a DLT during first the 3 weeks (Cycle 1) of the study treatment or 
receive ≥ 75% of scheduled Cycle 1 dose of APR-246 in combination with 
pembrolizumab and do not experience a DLT. Any individual subject who is not 
evaluable for DLT will be replaced by a new subject through additional subject 
enrollment. 
Efficacy evaluable (EE) population: All subjects who complete at least one treatment 
cycle of APR-246 in combination with pembrolizumab and who have at least one 
post-treatment clinical response assessment. Subjects who fail to complete one 
treatment cycle will also be considered EE if they show clear evidence of clinically 
significant disease progression. The EE population will be the secondary analysis 
population for efficacy. 
PK population: Subjects will be evaluable for PK if at least one post-dose sample for 
PK evaluation has been obtained. 
PK/Pharmacodynamic population: All the subjects who receive at least 1 dose of 
study drug (APR-246 pembrolizumab) and have evaluable pharmacodynamic and 
concentration data. 
Statistical analysis 
All the statistical analysis will be detailed in the statistical analysis plan.  
Generally, all the continuous variables will be summarized using n (number of 
subjects with available data), mean, standard deviation (StDev), median, and range 
(minimum and maximum). Categorical data will be summarized by frequency and 
percentage. Time to event data will be analyzed using Kaplan-Meier method, and the 
number and percentage of events, or censored, the first quartile at 25%, median with 
95% confidence, and third quartile at 75% of survival time will be presented. The 
survival rate at the 3, 6, 9, and 12 months, and then 2, 3 and 5 years will be presented. 
All the study data will be listed. 
Safety data including AEs, vital signs, laboratory data, electrocardiogram (ECG), 
physical exam, and ECOG performance status will be summarized in the safety 
population. AEs will be coded using the Medical Dictionary for Regulatory Activities 
(MedDRA) and graded using NCI-CTCAE v5.0 severity grade. 
The efficacy endpoints in the safety lead-in portion will be listed only. In the 
expansion phase, all the rates (ORR, DCR, durable SD, CBR) will be summarized with 
95% exact confidence intervals (Clopper and Pearson) by cohorts. The time to event 

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Protocol Number A20-11195  
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data (DOR, PFS, and OS) will be analyzed using Kaplan-Meier method and the 
corresponding survival plots will be produced.  
 
PK/safety relationships will be explored graphically and investigated by model-based 
analysis if appropriate. 
 
Pharmacokinetic Analysis 
The DDI between APR-246 and pembrolizumab will be evaluated using population 
PK (popPK) methods. The existing popPK model for APR-246 will be used to compare 
the observed plasma concentrations of APR-246 in presence of pembrolizumab with 
the predicted plasma concentrations assuming no DDI (visual predictive check). 
Additionally, the PK analysis dataset from this study will be integrated with the 
existing popPK dataset and the effect of pembrolizumab on APR-246 PK parameters 
will be tested as covariate in the model. 
 
Pharmacodynamic Analysis 
The effect of APR-246-pembrolizumab combination therapy on soluble, tissue, 
genetic and/or imaging biomarkers will be summarized using descriptive statistics 
using the PK/pharmacodynamic analysis set. PK/pharmacodynamic relationships will 
be explored graphically and may be investigated by model-based analyses. 

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Protocol Number A20-11195  
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LIST OF ABBREVIATIONS 
Abbreviation 
Definition 
AE 
Adverse event 
ADR 
Adverse drug reaction 
AML 
Acute myeloid leukemia 
ALT 
Alanine aminotransferase 
AST 
Aspartate aminotransferase 
AUC 
Area under curve 
AUCss 
Steady-state area under curve 
BUN 
Blood urea nitrogen 
CBR 
Clinical benefit rate 
CFR 
Code of Federal Regulations 
CHF 
Congestive heart failure 
CI 
Confidence interval 
CL 
Clearance 
CLL 
Chronic lymphocytic leukemia 
Cmax 
Maximum concentration 
Cmin 
Minimum concentration 
CNS 
Central nervous system 
CR  
Complete response 
CRO 
Contract Research Organization 
CT 
Computed tomography 
CTCAE 
Common Terminology Criteria for Adverse Events 
CYP450 
Cytochrome p450 
DCR 
Disease control rate 
DDI 
Drug-drug interaction 
DLT 
Dose-limiting toxicity 
DOR 
Duration of response 
DRM 
Data Review Meeting 
DRT 
Data Review Team 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
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eCRF 
Electronic case report form 
EC 
European Commission 
ECG 
Electrocardiogram 
ECOG 
Eastern Cooperative Oncology Group 
EE 
Efficacy evaluable 
EOI 
End of infusion 
ER 
Endoplasmic reticulum 
FDA 
Food and Drug Administration 
FFPE 
Formalin-fixed paraffin-embedded 
GEJ 
Gastroesophageal junction 
GCP 
Good Clinical Practice 
GLP 
Good Laboratory Practice 
HGSOC 
High grade serous ovarian cancer 
HIV 
Human immunodeficiency virus 
IB 
Investigator’s Brochure 
ICF 
Informed consent form 
ICH 
International Council for Harmonisation 
IEC 
Independent Ethics Committee 
IMP 
Investigational Medicinal Product 
IRB 
Institutional Review Board 
IV 
Intravenous 
LBM 
Lean body mass 
LD 
Longest diameter 
LVEF 
Left ventricular ejection fraction 
mAb 
Monoclonal antibody 
MQ 
2-methylene-quinuclidin-3-one 
MRI 
Magnetic resonance imaging 
MTD 
Maximum tolerated dose 
NCI 
National Cancer Institute 
NSCLC 
Non-small-cell lung cancer 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
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NGS 
Next-generation sequencing 
OS 
Overall survival 
ORR 
Overall response rate 
PBMC 
Peripheral blood mononuclear cell 
PD 
Progressive disease 
PD-1 
Programmed cell death protein 1 
PD-L1 
Programmed death-ligand 1 
PET 
Positron-emission tomography 
PFS 
Progression-free survival 
PK 
Pharmacokinetic(s) 
PLD 
Pegylated liposomal doxorubicin 
PO 
Orally (per os) 
PopPK 
Population pharmacokinetics 
PR 
Partial response 
QTcF 
Corrected QT interval by Fridericia 
Q3W 
Every 3 weeks 
RECIST 
Response Evaluation Criteria in Solid Tumors 
RNA 
Ribonucleic acid 
RP2D 
Recommended phase 2 dose 
R/R 
Relapsed/refractory 
SAE 
Serious adverse event 
SD 
Stable disease 
StDev 
Standard deviation 
TEAE 
Treatment-emergent adverse event 
tid 
Three times daily (ter in die) 
TrxR1 
Thioredoxin reductase 1 
T1/2 
Terminal half-life 
ULN 
Upper limit of normal 
USPI 
United States Prescribing Information 
Vd 
Volume of distribution 

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Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
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1.0 GENERAL INFORMATION 
1.1 
Protocol Number and Title of the Study 
Protocol No. A20-11195 
Protocol Title: Phase 1/2 Study of APR-246 in Combination with Pembrolizumab in Subjects 
with Solid Tumor Malignancies 
 
1.2 
Sponsor 
Aprea Therapeutics, Inc. 
 
 
 
1.3 
Monitor 
 
 
 
 
 
1.4 
Signature Authorization 
The protocol will be signed by Aprea Therapeutics. 
 
 

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Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
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2.0 BACKGROUND INFORMATION 
2.1 
APR-246 
 
 
 
 
 
 
  
 
2.2 
APR-246 Preclinical Studies 
2.2.1 Pharmacology and Mode of Action 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   
 
 
 
 
 
 
 
 
 
 
 
 
  
 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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2.2.3 Pharmacokinetics and Metabolism in Animals 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
2.3 
APR-246 Clinical Studies 
 
 
 
2.3.1 Phase 1/2 Study in Solid and Hematological Malignancies 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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2.3.2 Phase 1/1b Study in Refractory Hematologic Malignancies 
In 
 
 
 
 
 
 
 
 
 
 
2.3.3 Phase 1/2 Study in TP53-Mutant Advanced Ovarian Cancer 
 
 
 
 
 
 
 

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Protocol Number A20-11195  
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2.3.4 Phase 1b/2 Study in TP53-Mutant Myeloid Neoplasms 
 
 
 
  
 
 
 
 
 
 
2.3.5 APR-246 CNS Safety Overview 
 
 
 
 
 
 
 
 
 
 
 
 
 
2.3.6 APR-246 Cardiac Safety Overview 
 
 
   
 
 
 

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Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
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2.4 
Pembrolizumab 
The PD-1 receptor-ligand interaction is a major pathway hijacked by tumors to suppress 
immune control5. The normal function of PD-1, expressed on the cell surface of activated T 
cells under healthy conditions, is to down-modulate unwanted or excessive immune 
responses, including autoimmune reactions. PD-1 (encoded by the gene Pdcd1) is an Ig 
superfamily member related to CD28 and CTLA-4 which negatively regulates antigen 
receptor signaling upon engagement of its ligands (PD-L1 and/or PD-L2). The observed 
correlation of clinical prognosis with PD-L expression in multiple cancers suggests that the 
PD-1/PD-L1 pathway is involved in tumor immune evasion and is thus an attractive target 
for therapeutic intervention.  
 
Pembrolizumab is a potent and highly selective humanized monoclonal antibody (mAb) of 
the IgG4/kappa isotype which blocks the interaction between PD-1 and its ligands, PD-L1 
and PD-L2. Both pembrolizumab and the PD-1 inhibitor nivolumab contain the S228P 
stabilizing mutation and have no antibody-dependent cell-mediated cytotoxicity or 
complement-dependent cytotoxicity activity. Pembrolizumab enhances T lymphocyte 
immune responses in cultured blood cells from healthy human donors, cancer patients, 
and primates. Pembrolizumab also modulates levels of interleukin-2, tumor necrosis factor 
alpha, interferon gamma, and other cytokines. Importantly, pembrolizumab potentiates 
existing immune responses only in the presence of antigen and does not nonspecifically 
activate T cells. 
 
Pembrolizumab is approved by the Food and Drug Administration (FDA) for melanoma, 
non-small cell lung cancer (NSCLC), bladder cancer, renal cancer, gastric/gastroesophageal 
junction (GEJ) adenocarcinoma, and other malignancies. Across indications, the approved 
dose and schedule of pembrolizumab is 200 mg IV over 30-minute infusion every 3 weeks. 
Warnings and precautions include immune-mediate pneumonitis, colitis, hepatitis, 
endocrinopathies, skin reactions, and infusion-related reactions. The most common 
adverse reactions (reported in ≥ 20% of patients) were: fatigue, musculoskeletal pain, 
decreased appetite, pruritus, diarrhea, nausea, rash, pyrexia, cough, dyspnea, constipation, 
pain, and abdominal pain. In combination with chemotherapy, adverse drug reactions 
(ADRs) included fatigue/asthenia, nausea, constipation, diarrhea, decreased appetite, rash, 
vomiting, cough, dyspnea, pyrexia, alopecia, and peripheral neuropathy. In combination 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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with axitinib, ADRs included diarrhea, fatigue/asthenia, hypertension, hepatotoxicity, 
hypothyroidism, 
decreased 
appetite, 
palmar-plantar 
erythrodysesthesia, 
nausea, 
stomatitis/mucosal inflammation, dysphonia, rash, cough, and constipation. Table 1 in the 
United States Prescribing Information (USPI)6 provides recommended dose reductions of 
pembrolizumab in the setting of ADRs. 
 
The PK of pembrolizumab was characterized using a population PK (popPK) analysis with 
concentration data collected from 2,993 patients with various cancers who received 
pembrolizumab doses of 1 to 10 mg/kg every 2 weeks, 2 to 10 mg/kg every 3 weeks, or 
200 mg every 3 weeks. Steady-state concentrations of pembrolizumab were reached by 
16 weeks of repeated dosing with an every 3-week (Q3W) regimen and the systemic 
accumulation was 2.1-fold. The Cmax, minimum concentration (Cmin), and AUC at steady state 
(AUCss) of pembrolizumab increased dose proportionally in the dose range of 2 to 10 mg/kg 
every 3 weeks. 
 
Pembrolizumab CL% is approximately 23% lower [geometric mean, 195 mL/day (40%)] at 
steady state than that after the first dose [252 mL/day (37%)]; this decrease in CL with time 
is not considered clinically important. The terminal half-life (t1/2) is 22 days (32%). 
 
Regarding specific populations, the following factors had no clinically important effect on 
the CL of pembrolizumab: age (range: 15 to 94 years), sex, race (89% White), renal 
impairment (eGFR ≥ 15 mL/min/1.73 m2), mild hepatic impairment (total bilirubin ≤ upper 
limit of normal (ULN) and aspartate aminotransferase (AST) > ULN or total bilirubin 
between 1 and 1.5 times ULN and any AST), or tumor burden. The impact of moderate or 
severe hepatic impairment on the PK of pembrolizumab is unknown. 
 
2.5 
Rationale for Combination of APR-246 in with Pembrolizumab  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
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Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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2.6 
Rationale for Dose and Schedule of APR-246 in Combination with Pembrolizumab  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
utilized. 
 
2.7 
Potential Risks and Benefits 
2.7.1 Potential Risks 
 
   
 
 
 
 
 
 
 
 
 
 
  
 

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Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
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2.8 
Characteristics of a Well-Conducted Trial 
The following characteristics of an adequate and well-conducted trial will be implemented: 
 
1. The investigators will be well qualified by scientific training and experience. 
2. Detailed electronic Case Report Forms (eCRFs) will be completed for every subject.  
3. Requirements for institutional ethics review as set forth by the appropriate 
Institutional Review Board/Independent Ethics Committee (IRB/IEC), Title 21 Code of 
Federal Regulations (CFR) Part 56, the European Union Directive 2001/20/European 
Commission (EC) and its associated Detailed Guidances, European Union Good 
Clinical Practice (GCP) Directive 2005/28/EC, the International Council for 
Harmonisation (ICH) Guideline for GCP, Sections 3 and 4, and the terms of the 
Declaration of Helsinki (2013), will be followed.  
4. Requirements for informed consent in accordance with institutional guidelines, FDA 
requirements as specified in Title 21 CFR, Part 50, the European Union Directive 
2001/20/EC and its associated Detailed Guidances, European Union GCP Directive 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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2005/28/EC, the ICH Guideline for GCP, Section 4.8, and the terms of the Declaration 
of Helsinki (2013), will be followed.  
5. Safety data will be recorded and evaluated.  
6. Routine monitoring visits will be conducted by the Sponsor’s representative to ensure 
data accuracy.  
7. Drug accountability will be strictly maintained.  
8. This trial will be conducted according to GCP, the protocol and applicable regulatory 
requirements. 
 
2.9 
Subject Population 
This study will enroll adult male and female subjects of age ≥ 18 years with documented 
histologic diagnosis of solid tumor malignancies. Tumor TP53 mutation status is not required 
for enrollment. 
 
3.0 TRIAL OBJECTIVES AND PURPOSE 
3.1 
Primary objective:   
1. To evaluate the safety and tolerability of APR-246 in combination with 
pembrolizumab in subjects with solid tumors. 
2. To determine and confirm the maximum tolerated dose (MTD) for APR-246 in 
combination with 200 mg IV, Q3W pembrolizumab in subjects with solid tumor 
malignancies. 
 
3.2 
Secondary objectives: 
1. ORR of APR-246 in combination with pembrolizumab in subjects with solid tumor 
malignancies by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. 
2. Progression-free survival (PFS) by RECIST 1.1. 
3. Overall survival (OS). 
4. Duration of response (DOR) by RECIST 1.1. 
5. Disease control rate (DCR: CR + PR + stable disease [SD]) by RECIST 1.1 
6. Durable SD rate (durable SD [SD ≥23 weeks]) by RECIST 1.1 
7. Clinical benefit rate (CBR: CR, PR + durable SD) by RECIST 1.1. 
8. The PK profile of APR-246 during combination treatment with pembrolizumab. 
 
3.3 
Exploratory objectives: 
1. To investigate the relationship between candidate efficacy biomarkers and anti-
tumor activity of APR-246 in combination with pembrolizumab based on analyses of 
blood, serum, and/or tumor tissue. 
 
 

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Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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4.0 TRIAL DESIGN 
4.1 
Overview of Trial Design 
This is a phase 1/2, open-label, study to determine the safety and preliminary efficacy of 
APR-246 in combination with pembrolizumab in subjects with solid tumor malignancies.  
In the safety lead-in part of study (phase 1), the safety and the RP2D of APR-246 will be 
investigated. The RP2D of APR-246 will be defined as the dose at which < 2 out of 6 subjects 
experience DLT during the 3-week safety assessment period after the start of APR-246 
administration in combination with pembrolizumab using dose de-escalation of APR-246. 
In the expansion part of the study (phase 2), both safety and efficacy for the combination 
therapy will be investigated in the 3 cohorts.  
Study treatment may be administered on an outpatient basis. No investigational or 
commercial anti-tumor agents or therapies other than those described below may be 
administered with the intent to treat the patient's underlying malignancy.  
The study will include a safety lead-in dose-finding portion followed by expansion portion. 
During the safety lead-in portion of the study, subjects with (non-CNS primary) solid tumor 
malignancies will receive pembrolizumab in combination with APR-246 in a 3 + 3 dose de-
escalation design.  
Dosing will begin at the full dose of both drugs due to the well-established safety profiles of 
APR-246 and pembrolizumab, the non-overlapping mechanisms of action, and the intent to 
treat patients at doses shown to be effective in previous studies. Lower dose levels of 
APR-246 will be explored as necessary depending on observed AEs. 
The initial cohort of subjects will receive APR-246 at 4.5 g/day administered as an IV infusion 
on Days 1–4 in combination with pembrolizumab at the approved dose of 200 mg on Day 3 
of each 21-day cycle. This cohort will enroll up to a maximum or 6 subjects. DLT will be 
assessed after 3 subjects have been enrolled in each respective cohort and the last enrolled 
subject has completed the 3-week safety assessment period (i.e., one cycle of combination 
regimen). A subject that discontinues therapy during Cycle 1 without DLT is considered 
evaluable for the purpose of safety only if at least 75% of scheduled doses of APR-246 were 
administered in the first cycle. At the first dose level of 4.5 g/day of APR-246, if ≤ 1 subject 
out of 3 experiences a DLT, 3 additional subjects will be enrolled. If ≤ 1 subject out of 6 
experiences DLT, the dose level (4.5 g/day of APR-246) will be deemed the RP2D for that 
cohort. If ≥ 2 subjects out of the total 3 – 6 subjects in the cohort experience DLT, the study 
will continue enrollment at Dose Level -1 (4.0 g/day of APR-246) (see Table 1). If ≤ 1 subject 
out of 6 experiences DLT at this dose level, the dose level (4.0 g/day of APR-246) will be 
deemed the RP2D for that cohort. If ≥ 2 subjects out of 3 – 6 subjects at that Dose Level -1 
experience DLT, the study will continue enrollment at Dose Level -2 (3.5 g/day of APR-246). If 
≤ 1 subject out of 6 experiences DLT at this dose level, the dose level (3.5 g/day of APR-246) 
will be deemed the RP2D for that cohort. If ≥ 2 subjects out of 3 – 6 subjects at this dose level 

Aprea Therapeutics, Inc. 
Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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experience DLT, the trial will be halted and the Data Review Team (DRT) will consider 
potential future dosing modifications. No dose reductions in pembrolizumab are planned. 
Table 1. APR-246 Dose Levels 
Dose Modification 
APR-246 Dose 
Starting Dose Level 
(DL) 
APR-246 4.5 g/day 
1.5 g (for first 45 minutes) + 3.0 g (for 5 hours 15 minutes) 
Dose Level 
Reduction  
-1 (DL-1) 
APR-246 4.0 g/day  
1.33 g (for first 45 minutes) + 2.67 g (for 5 hours 15 minutes) 
Dose Level 
Reduction  
-2 (DL-2) 
APR-246 3.5 g/day  
1.17 g (for first 45 minutes) + 2.33 g (for 5 hours 15 minutes) 
 
Once the RP2D of APR-246 in combination with pembrolizumab has been determined, the 
expansion portion will begin in order to assess the anti-tumor activity of this combination in 
specific disease types. Up to 100 subjects will be enrolled in three cohorts of subjects with 
specific solid tumor malignancies as outlined in the schema. 
 
Throughout the study, subjects may study continue treatment as long as toxicity remains 
acceptable and the subject has not withdrawn consent. Response and progressive disease 
(PD) will be assessed based on RECIST 1.1 response criteria (APPENDIX V) as outlined in the 
Study Calendar. 
 
4.2 
End of Study 
The end of the study is defined as the date of the last visit of the last subject undergoing the 
trial. 
 
4.3 
Drug Products 
4.3.1 APR-246 
 
 
 
 
 
 

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4.3.2 Pembrolizumab 
Chemical Name: humanized X PD-1-mAb (H409A11) IgG4. 
 
Formulation, preparation, storage and stability: Please see pembrolizumab USPI6. 
 
Route of Administration: Pembrolizumab is administered by IV infusion over 30 minutes (±5 
minutes) at a dose of 200 mg every 3 weeks. 
 
4.4 
Duration of Therapy 
Subjects may remain on study treatment to the end of the trial while deriving clinical benefit, 
unless unacceptable toxicity, progression, death or subject withdrawal. Subjects may remain 
on protocol therapy after disease progression if they are continuing to derive clinical benefit 
in the opinion of the investigator. 
 
4.5 
Trial Discontinuation  
The Sponsor may terminate this study prematurely. Written notification of the termination 
is required. Conditions that may warrant termination include, but are not limited to: 
 
• 
The discovery of an unexpected, significant, or unacceptable risk to the subjects enrolled 
in the study. 
• 
Failure of the investigator to enter subjects at an acceptable rate. 
• 
Insufficient adherence to protocol requirements (non-compliance). 
• 
Lack of evaluable and/or complete data. 
• 
Decision to modify the developmental plan of the drug. 
• 
A decision on the part of the Sponsor to suspend or discontinue development of the drug. 
 
4.6 
Drug Accountability/Disposition of Clinical Trial Supplies 
The Investigator or designee will maintain accurate records of receipt and the condition of 
the study drug supplied for this study, including dates of receipt. In addition, accurate 
records will be kept of when and how much study drug is dispensed and administered to 

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each patient in the study. Any reasons for departure from the protocol dispensing regimen 
must also be recorded.  
 
At the completion of the study, there will be a final reconciliation of all study drugs. 
 
4.7 
Registration 
Prior to registration and any study-specific evaluations being performed, all subjects must 
have given written informed consent for the study and must have completed the pre-study 
evaluations (see Section 7.1). Subjects must meet all of the eligibility requirements listed in 
Section 5.0. Subjects will be registered on the study by using the
 Oncology 
Interactive Web Response System automated subject registration system. 
 

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5.0 SELECTION AND WITHDRAWAL OF SUBJECTS 
5.1 
Inclusion Criteria: 
1. Signed informed consent form (ICF) and ability to comply with protocol requirements. 
2. Known tumor TP53 mutation status from recent or archival sample. 
3. Histologically and/or cytologically confirmed solid tumor malignancy: 
a. Safety lead-in portion:  
i. 
Patients with histologically and/or cytologically confirmed diagnosis of 
advanced non-CNS primary tumors that have progressed after first line 
treatment, who are intolerant to first line treatment, or who are unable to 
receive first line treatment, and for whom pembrolizumab, or 
pembrolizumab-based therapy, is considered appropriate in the opinion 
of the investigator. Primary CNS tumors are excluded. Patients with 
clinically stable, known metastatic tumors to the CNS are eligible. CNS 
radiography is not required in the absence of suspicion for clinical 
involvement. 
b. Phase 2 Expansion portion:  
i. 
Patients with histologically and/or cytologically confirmed diagnosis of 
advanced gastric or GEJ tumors that have progressed after first line 
treatment, who are intolerant to first line treatment, or who are unable to 
receive first line treatment. Patients with clinically stable, known metastatic 
tumors to the CNS are eligible with Medical Monitor approval. CNS 
radiography is not required in the absence of suspicion for clinical 
involvement. Prior treatment with anti-PD-1/anti-PD-L1 therapy is 
prohibited.  
ii. 
Patients with histologically and/or cytologically confirmed diagnosis of 
advanced bladder/urothelial tumors that have progressed after first line 
treatment, or who are intolerant to first line treatment, or who are unable 
to receive first line treatment with cisplatin-based chemotherapy. Patients 
with clinically stable, known metastatic tumors to the CNS are eligible with 
Medical Monitor approval. CNS radiography is not required in the absence 
of suspicion for clinical involvement. Prior treatment with anti-PD-1/anti-
PD-L1 therapy is prohibited is prohibited. 
iii. 
Patients with histologically and/or cytologically confirmed diagnosis of 
advanced NSCLC previously treated with anti-PD-1 or anti-PD-L1 therapy. 
Patients with clinically stable, known metastatic tumors to the CNS are 
eligible with Medical Monitor approval. CNS radiography is not required in 
the absence of suspicion for clinical involvement.  
4. Adequate organ function as defined by the following laboratory values: 
a. Creatinine clearance > 30 mL/min (by Cockcroft-Gault method, APPENDIX I), 
b. Total serum bilirubin < 1.5 × ULN unless due to Gilbert’s syndrome, tumor 
involvement, hemolysis or considered an effect of regular blood transfusions, 

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c. Alanine aminotransferase (ALT) and AST < 3 × ULN, unless due to involvement 
by the underlying malignancy. 
5. Age ≥ 18 years at the time of signing the ICF. 
6. Eastern Cooperative Oncology Group (ECOG) performance status of 0, 1 or 2 (APPENDIX 
II). 
7. Projected life expectancy of ≥ 12 weeks. 
8. In the expansion portion, measurable disease meeting the following criteria: 
a. At least 1 lesion of ≥10 mm in the longest diameter (LD) for a non-lymph node 
or ≥15 mm in the short-axis diameter for a lymph node that is serially 
measurable according to RECIST 1.1. 
b. Lesions that have had external beam radiotherapy or loco-regional therapies 
such as radiofrequency ablation must show subsequent evidence of substantial 
size increase (ex. 20% increase in LD) to be deemed a target lesion. 
9. Negative serum or urine pregnancy test prior to study treatment initiation in female 
subjects of childbearing potential. 
10. Women of childbearing potential and men with female partners of childbearing potential 
must be willing to use an effective form of contraception such as latex condom, hormonal 
birth control, intrauterine device or double barrier method (APPENDIX III) during 
chemotherapy treatment and for at least six months thereafter. 
 
5.2 
Exclusion Criteria 
1. Known history of untreated human immunodeficiency virus (HIV)/HIV with a detectable 
viral load or active hepatitis B or active hepatitis C infection. 
2. Any of the following cardiac abnormalities: 
a. Myocardial infarction within six months prior to registration; 
b. New York Heart Association Class III or IV (APPENDIX IV) heart failure or known 
left ventricular ejection fraction (LVEF) < 40%; 
c. A history of familial long QT syndrome; 
d. Symptomatic atrial or ventricular arrhythmias not controlled by medications; 
e. QTcF ≥ 470 msec, unless due to underlying bundle branch block and/or 
pacemaker and with approval of the Medical Monitor. 
3. Concomitant malignancies or previous malignancies with less than a 1-year disease-free 
interval at the time of signing consent. Subjects with adequately treated basal or 
squamous cell carcinoma of the skin, or adequately treated carcinoma in situ (e.g. cervix) 
may enroll irrespective of the time of diagnosis. Patients with controlled, advanced 
prostate cancer are permitted. 
4. Pregnancy or lactation. 
5. Active uncontrolled systemic infection. 
6. An autoimmune condition requiring ≥ 10 mg (or equivalent corticosteroid) prednisone 
daily, or any other systemic immunosuppressive treatment within 28 days of first dose 
of study therapy. 
7. Known history of active tuberculosis. 

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8. Current (non-infectious) pneumonitis, or a history of pneumonitis that required steroids. 
9. A live vaccine administered within 30 days of the first dose of study treatment. 
10. Receipt of any investigational product within 14 days or 5 half-lives prior to study 
treatment initiation, whichever is shortest. 
11. Prior intolerance to pembrolizumab or other immune-oncology agents. 
 
5.3 
Inclusion of Women, Minorities and Children 
Both men and women and members of all races and ethnic groups are eligible for this study. 
Children are not eligible for this study because the safety and tolerability of the proposed 
dosing schedule has not been determined in adults. 
 
5.4 
Withdrawal Criteria 
Subjects are free to discontinue treatment or withdraw from the study at any time and for 
any reason, without penalty to their continuing medical care. Any discontinuation of 
treatment or withdrawal from the study must be fully documented in the eCRF and should 
be followed up by the Investigator. The Investigator may withdraw a patient at any time if 
this is considered to be in the patient’s best interest. 
 
5.4.1 Study Treatment Discontinuation 
Study treatment must be discontinued if: 
• 
There is evidence of disease progression. Subjects who have PD but who are 
continuing to derive clinical benefit in the opinion of the investigator may continue to 
receive study treatment. 
• 
A subject becomes pregnant. 
• 
A subject is significantly non-compliant with the requirements of the protocol.  
• 
A subject has an adverse experience that would, in the investigator’s judgment, make 
continued participation in the study an unacceptable risk. 
• 
The subject starts new treatment for their underlying disease. 
 
5.4.2 Study Discontinuation 
Subject is discontinued from the study if: 
• 
The subject dies during the study. 
• 
The subject is lost to follow-up. 
• 
The subject withdraws consent. 

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5.4.3 Withdrawn Subjects  
When a subject is removed from the study treatment, the investigator will clearly document 
the reason in the medical record and complete the appropriate eCRF page describing the 
reason for discontinuation. In addition, every effort should be made to complete the 
appropriate assessments listed in Section 7.3. 
 
5.5 
Noncompliance 
All instances of protocol deviations will be recorded according to guidelines per Sponsor’s 
Representative.  
 
6.0 TREATMENT OF SUBJECTS 
6.1 
Drug Preparation and Administration 
Study treatment may be administered on an outpatient basis. No investigational or 
commercial agents or therapies other than those described below may be administered with 
the intent to treat the subject’s disease. 
 
APR-246 
APR-246 is administered as a 6-hour IV infusion daily on Days 1–4 of each 21-day cycle. 
APR-246 fixed dose is 4.5 g. APR-246 is administered in a 2-step infusion: 
 
• 
Step 1: Loading dose of 1.5 g for the first 45 minutes (± 2 min) 
• 
Step 2: Maintenance dose of 3 g over 5 hours 15 minutes (± 30 min) 
 
The dose of APR-246 may be reduced (please consult Section 4.1 and Table 1) or treatment 
interrupted if the subject develops AEs. 
 
APR-246 vials are to be stored at 2 – 8C (35.6 – 46.4F). At the pharmacies and at the study 
centers, the prepared APR-246 study product (diluted in sodium chloride solution) is to be 
stored at no greater than 25ºC. The infusion should be completed within 24 hours from the 
time of preparation.  
 
Detailed instructions on vial concentration, preparation and dispensing can be found in the 
Pharmacy Binder. The infusion timing, including start/stop times and the time of rate change, 
must be recorded. 
 

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Pembrolizumab 
 
Pembrolizumab at a dose of 200 mg is to be administered on Day 3 ±1 day of each cycle 
before the Day 3 dose of APR-246.  
 
6.1.1 Dose-Limiting Toxicity 
A DLT is defined as any of the following: 
• 
Any of the hematological or nonhematological toxicities noted in the table below 
considered to be at least possibly related to APR-246 occurring during the 
3-week safety assessment period after the start of APR 246 administration in 
combination with pembrolizumab (Cycle 1 Day 1). 
• 
Failure to administer ≥75% of the planned dosage of APR-246 as a result of 
treatment-related toxicity during Cycle 1, unless reversible CNS-related effects 
previously described for APR-246. 
• 
Subjects who discontinue treatment due to treatment-related toxicity. 
• 
Greater than 4-week delay in starting Cycle 2 because of a treatment-related 
toxicity, even if the toxicity does not meet DLT criteria. 

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Dose-Limiting Toxicities 
Toxicity Category 
Toxicity CTCAE Grade 
Hematologic 
Grade 4 neutropenia for ≥ 7 days 
Grade 3 or Grade 4 febrile neutropenia a 
Thrombocytopenia <25,000/mm3 associated with bleeding and/or that 
requires platelet transfusion 
Other nonhematologic 
toxicity 
Any other Grade 4 or a Grade 5 toxicity 
Grade 3 toxicities lasting > 3 days excluding: 
Nausea, vomiting, fatigue and diarrhea controlled by medical 
intervention within 72 hours. 
Grade 3 rash in the absence of desquamation, no mucosal involvement, 
does not require steroids, and resolves to Grade 1 by the next 
scheduled dose of pembrolizumab. 
Grade 3 hypertension not able to be controlled by medication 
Grade 3 or above gastrointestinal perforation 
Grade 3 or above wound dehiscence requiring medical or surgical 
intervention 
Any grade thromboembolic event 
Any Grade 3 non-hematologic laboratory value if: Medical intervention is 
required to treat the subject, or the abnormality leads to hospitalization 
ANC = absolute neutrophil count, CTCAE = Common Terminology Criteria for Adverse Events v5.0. 
a Febrile neutropenia Grade 3 or Grade 4: 
Grade 3 is defined as ANC < 1000/mm3 with a single temperature of >38.3 °C (101 °F) or a sustained temperature of ≥ 38 °C 
(100.4 °F) for more than one hour. 
Grade 4 is defined as ANC < 1000/mm3 with a single temperature of >38.3 °C (101 °F) or a sustained temperature of ≥ 38 °C 
(100.4 °F) for more than one hour, with life-threatening consequences and urgent intervention indicated 
 
Only toxicities with a clear alternative explanation (e.g., due to disease progression) or 
transient (≤ 72 hours) abnormal laboratory values without associated clinically significant 
signs or symptoms based on investigator determination can be deemed a non-DLT.  
 
All subjects enrolled in the safety lead-in portion will be assessed for DLTs during the 3-week 
DLT assessment period of Cycle 1. Subjects who discontinue study treatment prior to 
completing Cycle 1 of study treatment for any reason other than DLT will be replaced. 
 
Additionally, AEs that meet the above criteria, but occur after the DLT evaluation period will 
not be defined as DLTs, but will be reported as AEs/SAEs and will be reviewed across all 
cohorts during the study to help determine the AE profile. 
 
6.1.2 Recommended Phase 2 Dose (RP2D)  
The RP2D of APR-246 will be defined as the dose at which < 2 out of 6 subjects experience 
DLT during the 3-week safety assessment period after administration of APR-246 in 
combination with pembrolizumab. 
 

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A DRT consisting of the Medical Monitor, Site Principal Investigators, and other clinical 
research personnel that the Sponsor may deem appropriate, will hold Data Review Meetings 
(DRM) on an interim basis at a frequency dependent upon study accrual. At these meetings, 
the DRT will review AEs and DLTs and make recommendations regarding the RP2D. In the 
expansion portion of the study, the DRT will evaluate safety and tolerability after 5 subjects 
have completed 1 cycle of treatment in each cohort. All accumulated safety data will be 
discussed during DRMs. 
 
6.2 
Dose Interruptions/Withholding  
Study treatment may be withheld from a subject based on the investigator‘s decision in the 
event of intercurrent illness, AE, administrative reasons, or other reasons. If the subject’s 
condition subsequently improves, or the situation that resulted in withholding study drug 
rectifies itself, the investigator may resume dosing as soon as possible, unless the delay is 
more than 4 weeks. 
 
Dosing should be delayed for any DLT-equivalent toxicity and possible National Cancer 
Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) > Grade 2 AEs 
considered related to study medication. At the investigator’s discretion, dosing may 
recommence when the toxicity has resolved to Grade 2 or less. Immune-related reactions or 
allergy should resolve to ≤ Grade 1. 
 
Treatment will be discontinued if a treatment-emergent AE (TEAE) has not resolved (to 
acceptable grade) after ≤ 3 weeks. 
 
6.3 
Supportive Management 
6.3.1 Cardiac Monitoring 
This section outlines the requirements for proceeding with treatment with APR-246, and the 
protocol rules for APR-246 dose modification due to AEs.  
 
At screening, 12-lead ECGs should be collected in triplicate to confirm QT interval does not 
exceed 470 msec. QT interval must be calculated from a mean of all three ECG readings using 
Fridericia’s correction (QTcF = QT/RR0.33). 
 
During Cycle 1, ECG should be collected in triplicate prior to infusion of APR-246 and at the 
end of infusion (EOI) of APR-246 (6 hours after start of infusion, ± 30 min) on Days 1–4. QTcF 
must be calculated from a mean of all three ECG readings to confirm it does not exceed 
470 msec.  
 
If a pre-dose ECG shows QTcF ≥ 470 msec, the QTc reading should be confirmed by manual 
assessment using Fridericia’s correction (QTcF = QT/RR0.33). Serum concentrations of 

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electrolytes should be monitored and corrected, if necessary. Additionally, concomitant 
medication should be reviewed and adjusted, if necessary. ECG may be repeated at any time, 
including the same day. APR-246 may only be administered when QTcF has returned to 
< 470 msec. If APR-246 is given on the same day, procedures outlined in the Schedule of 
Study Evaluations (Table 4) must be followed. If APR-246 cannot be administered on the 
same day, that dose must be omitted from the cycle. 
 
If there is a significant change in QTcF, defined as either: a) increase > 60 msec from baseline 
(or pre-dose), or b) increase to an absolute value ≥ 501 msec, i.e. consistent with NCI-CTCAE 
Grade 3 QTc prolongation, QTc prolongation must be confirmed by a manual assessment of 
the ECG, and using Fridericia’s correction (QTcF = QT/RR0.33). If confirmed, the therapy should 
be interrupted until a cause (electrolyte disorders or an effect of a concomitant medication) 
has been identified and addressed, and QTcF has returned to < 470 msec. If all other causes 
for clinically significant QT interval prolongation are excluded, APR-246 must be permanently 
discontinued. 
 
During subsequent cycles, ECG should be collected in triplicate prior to infusion of APR-246 
on Day 1 of each cycle. QTcF must be calculated from a mean of all three ECG readings to 
confirm it does not exceed 449 msec. If pre-dose QTcF is 450-469 msec, APR-246 may be 
administered, and additional triplicate ECG should be performed at the EOI (6 hours after 
start of infusion, ± 30 min). If post-dose ECG shows a significant change in QTcF, defined as 
either: a) increase > 60 msec from baseline (or pre-dose), or b) increase to an absolute value 
≥ 501 msec, i.e. consistent with NCI-CTCAE Grade 3 QTc prolongation, QTc prolongation must 
be confirmed by a manual assessment of the ECG, and using Fridericia’s correction (QTcF = 
QT/RR0.33). If confirmed, the therapy should be interrupted until a cause (electrolyte disorders 
or an effect of a concomitant medication) has been identified and addressed, and QTcF has 
returned to < 470 msec. If all other causes for clinically significant QT interval prolongation 
are excluded, APR-246 must be permanently discontinued. If QTcF is unchanged or there is 
no significant change, additional ECG is not required during that cycle. 
 
If repeated QTcF measurements show a stable QTcF < 450 msec, or if QTcF remains stable 
within the interval of 450 – 469 msec with no significant change at the EOI during several 
cycles of treatment, reducing the number of ECGs performed in the study may be discussed 
with the Medical Monitor. 
 
If a subject starts treatment with another medication known to prolong QT interval at any 
time during the study therapy, an additional pre- and post-dose (6 hours after start of 
infusion, ± 30 min) ECG should be performed on the next treatment day.  
 
6.3.2 Management of CNS Adverse Events  
If, during the administration period of APR-246, a subject experiences an AE that could be 
considered to originate from the CNS (e.g. dizziness, vertigo, nausea), medical management 

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is recommended as per institutional standard of care. Prompt discussion with the Medical 
Monitor is recommended. 
 
Treatment with prochlorperazine 10 mg orally three times daily (tid) PRN has been reported 
to effectively treat CNS AE. Prochlorperazine may also be used prophylactically. When 
prochlorperazine is used prophylactically, it is recommended that treatment start the day 
prior to the Day 1 and continue at 10 mg tid through Day 4 as needed. It is important to 
record the dose and time of prochlorperazine administration in the eCRF. 
 
In addition, dose modifications have been successfully used to manage CNS AEs occurring 
during the infusion (Table 2). For any clinical AE Grade ≥ 3, the infusion should be interrupted 
and if the AE resolves to CTCAE ≤ Grade 1 within 2 hours, the infusion may be resumed at 
the same infusion rate. If similar symptoms recur during re-challenge the infusion should be 
interrupted. 
 
If an AE lasts longer than 2 hours, then the APR-246 infusion should be discontinued for that 
day, the remaining drug should be discarded. 
 
Table 2. Management of CNS Adverse Events (Dizziness, Dyskinesia and Ataxia) 
 
Worst toxicity  
Dose Modifications for APR-246 
Grade 1 
Maintain dose level 
Grade 2 
If resolved to ≤ Grade 1 with medical therapy, continue same dose level. 
If not resolved despite treatment interruption and maximal medical therapy, 
stop infusion and  1 dose level for subsequent dose 
Grade ≥ 3 
Stop infusion and give medical therapy. If resolved (to ≤ Grade 1) with medical 
therapy, infusion may continue at the investigator’s discretion. 
  1 dose level for subsequent dose  
Grade 4 
Permanently discontinue subject from APR-246. 
 
 
6.3.3 Management of Nausea and Vomiting  
For subjects who experience nausea and/or vomiting in association with APR-246, treatment 
with anti-emetics is recommended per institutional guidelines. Use of medications that 
prolong the cardiac QT interval is discouraged. For subjects who receive medications known 
to cause QT prolongation, the QT must be monitored via ECG before and after the APR-246 
infusion. 
 
• 
If QTc > 501 msec is observed in a subject concomitantly treated with another QT 
interval prolonging drug, this drug should be stopped and treatment with APR-246 
may be restarted when QTc < 470 msec (refer to Section6.3.1). 
 

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A list of suggested rescue medications is provided below in Table 3. 
Table 3. Medications for Managements of Nausea and Vomiting 
Drug 
Dosage 
QT Prolongationa 
Ondansetron 
8 mg orally (PO) administered 30 minutes before 
the start of infusion or per label 
Yes 
Dolasetron 
100 mg PO administered within one 
hour before start of infusion or per label 
Yes 
Palonosetron 
0.5 mg PO administered approximately one 
hour prior to the start of infusion or per label 
No 
Prochlorperazine 
10 mg PO three times daily. Continue until the 
end of Day 4 of the cycle. When used 
prophylactically in subsequent cycles, start the 
day prior to Day 1 administration of APR-246 
No 
a Please refer to Section 6.3.1 for details on concurrent administration of medications known to cause QTc 
interval prolongation. 
 
6.3.4 Management of Infusion Reactions 
6.3.4.1 APR-246 
If a subject experiences an infusion reaction considered related to APR-246, the infusion 
should be immediately interrupted and appropriate medical care (e.g., epinephrine, oxygen, 
H1 and H2 antagonists, and/or corticosteroids) administered9. 
 
6.3.4.2 Pembrolizumab 
Pembrolizumab is to be administered only under the care of a physician experienced in the 
use of pembrolizumab in treating subjects with solid tumor malignancies. 
 
Dose Modification and Toxicity Management for Immune-related AEs Associated with 
Pembrolizumab 
 
AEs associated with pembrolizumab exposure may represent an immunologic etiology. 
These immune-related AEs may occur shortly after the first dose or several months after the 
last dose of pembrolizumab treatment and may affect more than one body system 
simultaneously. Therefore, early recognition and initiation of treatment is critical to reduce 
complications. In clinical studies, most AEs were reversible and could be managed with 
interruptions of pembrolizumab, administration of corticosteroids and/or other supportive 
care. For suspected AEs, ensure adequate evaluation to confirm etiology or exclude other 
causes. Additional procedures or tests such as bronchoscopy, endoscopy, skin biopsy may 
be included as part of the evaluation. Based on the severity of AEs, withhold or permanently 
discontinue pembrolizumab and administer corticosteroids. Dose modification and toxicity 
management guidelines for ARs associated with pembrolizumab are provided in the USPI6. 

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Dose Modification and Toxicity Management of Infusion Reactions Related to Pembrolizumab 
 
Pembrolizumab may cause severe or life-threatening infusion-reactions including severe 
hypersensitivity or anaphylaxis. Signs and symptoms usually develop during or shortly after 
drug infusion and generally resolve completely within 24 hours of completion of infusion. 
Dose modification and toxicity management guidelines on pembrolizumab associated 
infusion reaction are provided in the USPI6. 
 
6.4 
Concomitant Treatment  
Subjects must not receive any other concurrent anti-cancer therapy, including investigational 
anti-cancer agents, while on study treatment.  
 
Subjects may continue their baseline medication(s) as long as they are not prohibited. 
Prohibited mediations include systemic immunosuppressive treatment [ex. prednisone ≥ 10 
mg/day (or equivalent corticosteroid)], live vaccines and investigational anti-tumor products. 
Palliative and supportive care (e.g., anti-emetics, bisphosphonates) for disease-related 
symptoms may be utilized according to institutional practices. AEs will be treated as clinically 
indicated. All concomitant medications should be recorded in the eCRF. 
 
If the subject develops an acute infusion reaction ( Grade 2), the infusion must be 
interrupted until the reaction is resolved to ≤ Grade 1. Premedication (e.g., systemic 
corticosteroids) may be used as required. 
 
6.5 
Monitoring Subject Compliance 
This study will be monitored by Aprea Therapeutics, Inc. or its Contract Research 
Organization (CRO) according to ICH E6 guidelines of GCP. The study site monitor will 
regularly visit the study sites to ensure that the study is conducted according to the protocol 
and GCP principles. All instances of protocol deviations will be entered and reviewed by the 
investigator, Sponsor and appropriate 
 designee.  
 
 
7.0 STUDY EVALUATIONS 
 
7.1 
Schedule of Study Evaluations 
Study evaluations are summarized in Table 4 and described in Sections 7.2 through 7.4. 
 

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Table 4. Study Calendar 
Study Calendar 
Evaluation a 
Screening a 
(28 days) 
Cycle 1 (21 days) 
Cycle 2 and Subsequent Cycles 
End of 
Treatment r 
Long-
Term 
Follow-
up s 
D1 
D2 
D3 
D4 
D8 b, e 
D15 b, e 
D1c 
D2 
D3 
D4 
 
Informed consent 
× 
 
 
 
 
 
 
 
 
 
 
 
 
Medical history d 
× 
 
 
 
 
 
 
 
 
 
 
 
 
Physical examination e 
× 
× 
 
 
 
 
 
× 
 
 
 
× 
 
Height 
× 
 
 
 
 
 
 
 
 
 
 
 
 
Weight 
× 
× 
 
 
 
 
 
× 
 
 
 
× 
 
Vital signs e 
× 
× 
× 
× 
× 
 
 
× 
× 
× 
× 
× 
 
ECOG PS 
× 
× 
 
 
 
 
 
× 
 
 
 
× 
 
APR-246 f 
 
× 
× 
× 
× 
 
 
× 
× 
× 
× 
 
 
Pembrolizumab g 
 
 
 
× 
 
 
 
 
 
× 
 
 
 
Disease assessment h 
× 
 
 
 
 
 
 
× h 
 
 
 
× 
 
Hematology i 
× 
× 
 
 
 
× 
× 
× 
 
 
 
× 
 
Serum chemistry j 
× 
× 
 
 
 
× 
× 
× 
 
 
 
× 
 
Pregnancy test k 
× 
 
 
 
 
 
 
 
 
 
 
 
 
ECG l 
× 
×l 
×l 
×l 
×l 
 
 
×l 
 
 
 
 
 
APR-246 PK sample m 
 
× 
× 
× 
× 
 
 
× 
× 
× 
× 
 
 
Archival tissue collection n 
× 
 
 
 
 
 
 
 
 
 
 
 
 
Fresh tissue biopsy o 
× 
 
 
 
 
 
 
× 
 
 
 
 
 
Blood for biomarkers p 
× 
× 
 
 
 
 
 
× 
 
 
 
× 
 
Blood for PBMC q 
× 
× 
 
 
 
 
 
× 
 
 
 
× 
 
Clinical toxicity assessment 
 
Starting at the time of study treatment initiation through 30 days after last dose t 
 
Concomitant medications 
Reviewed throughout study 
 
Survival 
 
 
 
 
 
 
 
 
 
 
 
× 
× 
 

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Footnotes to Study Calendar 
 
a. All screening/baseline evaluations are performed within 28 days prior to the start of study 
treatment. In the event that a visit or test cannot be scheduled on the exact visit day, a window of 
±3 days is allowable. 
b. A window of ±3 days applies to this study visit. 
c. After the first cycle, Day 1 evaluations of subsequent cycles are to be done within 3 days prior to 
next cycle drug administration. 
d. Full medical history is obtained at screening for safety and eligibility purposes; this will include any 
clinically significant findings from 28 days prior to screening date. 
e. Physical exam and vital signs (including blood pressure, heart rate, respiration rate and 
temperature) are completed for safety purposes and clinically significant items are recorded as 
AEs where appropriate. Vital signs are collected prior to APR-246 infusion, 2 hours into infusion 
and at EOI (±30 minutes at all time points). 
f. 
APR-246 is administered IV on Days 1–4 of each 21-day cycle. 
g. Pembrolizumab at a dose of 200 mg is to be administered on Day 3 ±1 day of each cycle before 
the Day 3 dose of APR-246. 
h. Disease assessment should be conducted every 9 weeks (±3 days) after initiating study treatment, 
prior to initiation of each odd treatment cycle starting at Week 9, then every 6 weeks through the 
first year and then every 9 weeks, thereafter. Magnetic resonance imaging (MRI) may be used 
instead of computed tomography (CT) for head, neck, abdomen, and pelvis; however, the chest 
must be assessed using CT. Chest disease may not be followed using chest x-ray. 
Positron-emission tomography (PET) scanning should not be used, but PET/CT may be used if CT 
component is with contrast enhancement and of diagnostic quality. The same modality (CT, MRI, 
and/or PET) that is used for baseline disease assessment should be used throughout the study.  
i. 
Hematology must include complete blood count with differential. 
j. 
Serum chemistry must include sodium, potassium, chloride, CO2, blood urea nitrogen (BUN), 
creatinine, glucose, calcium, albumin, total protein, total bilirubin, AST, ALT, alkaline phosphatase, 
Thyroid Stimulating Hormone (TSH) and free T4. 
k. Serum or urine βhCG must be performed within 7 days prior to study treatment initiation in 
female subjects of childbearing potential. 
l. 
Standard 12-lead ECGs in triplicate at screening, on Days 1–4 of Cycle 1 and on Days 1 of each 
subsequent cycle with subject in a semi-recumbent position. Please consult Table 6 for ECG 
collection schedule.  
m. Please consult Section 8.5 for PK collection schedule. 
n. Tumor block or 20 unstained, 4-µm thick, paraffine-embedded tumor slides from an archival 
tissue sample, if available. 

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o. Optional: Percutaneous or endoscopic biopsy of a tumor lesion will be only performed at baseline 
(within 2 weeks prior to treatment initiation) and at Cycle 2 Day 1 (±5 days). Biopsy samples will 
be formalin-fixed, paraffin embedded and snap frozen.  
p. Blood for serum analysis is collected on specific 5-mL dry tubes at screening, prior to treatment 
initiation at Cycle 1 Day 1, and at the time of second tumor biopsy/or prior to Cycle 2 Day 1 
treatment if no biopsy is done. 
q. Blood for PBMC isolation is collected in four 10-mL CPT tubes (total, 40 mL) at screening, prior to 
treatment initiation at Cycle 1 Day 1, and at the time of second tumor biopsy/or prior to Cycle 2 
Day 1 treatment, if no biopsy is done. Additional PBMCs will be collected prior to Cycle 5 Day 1 
treatment and 30 days after treatment discontinuation. 
r. 
Subjects discontinuing treatment should complete their end of treatment visit 30 days after their 
last dose of APR-246. Physical exam, vital signs, clinical toxicity assessment, hematology, serum 
chemistry and disease assessment should be performed, if feasible.  
s. Long-term follow up can be done remotely (e.g. via telephone, via local practitioner or via review 
of medical records). Assuming there is no withdrawal of consent, subjects who stop study 
treatment for any reason (e.g. toxicity, PD) will continue long-term follow-up (see Section 7.4). If a 
subject is removed from the study due to unacceptable AEs, the event(s) will be followed until 
resolution or stabilization of the AE. 
t. 
AE description, grade and start date and resolution date should be documented. 

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7.1.1 Screening 
All screening evaluations are to be performed within approximately 28 days of study 
treatment initiation, unless otherwise noted. 
• 
Signed written informed consent  
• 
Medical history  
• 
Physical examination 
• 
Height 
• 
Weight  
• 
ECOG performance status (APPENDIX II) 
• 
Vital signs, including blood pressure, heart rate, respiration rate and temperature 
• 
Hematology, including complete blood count with white blood cell differential.  
• 
Serum chemistry, including sodium, potassium, chloride, CO2, BUN, creatinine, 
glucose, calcium, albumin, total protein, total bilirubin, AST, ALT, alkaline 
phosphatase, TSH and free T4 
• 
Creatinine clearance (Cockcroft-Gault method; APPENDIX I) 
• 
Serum or urine βhCG must be performed within 7 days prior to study treatment 
initiation for female subjects of childbearing potential. 
• 
ECG: standard 12-lead ECGs with subject in a semi-recumbent position in triplicate. 
• 
Concomitant medication review 
• 
Optional: Archival tissue collection  
• 
Optional: Fresh tissue biopsy 
• 
Blood for biomarkers 
• 
Blood for PBMC 
• 
Baseline disease assessment at a minimum must include imaging of chest, abdomen 
and pelvis (CT, MRI, and/or PET) for subjects with gastric/GEJ adenocarcinoma, 
urothelial cancer and non-small cell lung cancer. The same modality should be used 
throughout the study. 
 
7.2 
Pre-Study Assessments 
Prior to performing any procedures or assessments, the nature of the study and the 
potential risks associated with the trial will be explained to all subject candidates and written 
informed consent will be obtained. Subjects who choose to participate will have to consent 
to the biobanking program and will be asked to sign the mandatory section in the main study 
consent form related to biobank samples. Evaluations obtained as part of routine medical 
care and performed during the screening period may be used in place of the study specific 
evaluations. Subjects will acknowledge and agree to the possible use of this information for 
the study by giving informed consent.  
 

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7.2.1 Cycle 1 
7.2.1.1 Cycle 1 Days 1–4 
Day 1 examinations marked * do not need to be repeated if already performed within 3 days 
prior to Day 1 Cycle 1.   
 
• 
Clinical toxicity assessment 
• 
Concomitant medications review 
• 
Physical examination: Day 1*  
• 
Weight: Day 1* 
• 
ECOG performance status (Day 1*; APPENDIX II) 
• 
Vital signs, including blood pressure, heart rate, respiration rate and temperature, 
collected 2 hours into APR-246 infusion (± 30 min) and at EOI (± 30 min) 
• 
Hematology (Day 1*), including complete blood count with white blood cell 
differential 
• 
Serum chemistry (Day 1*), including sodium, potassium, chloride, CO2, BUN, 
creatinine, glucose, calcium, albumin, total protein, total bilirubin, AST, ALT, alkaline 
phosphatase, TSH and free T4 
• 
Blood for biomarkers (Day 1*) 
• 
Blood for PBMC (Day 1*) 
• 
ECG: standard 12-lead ECG with subject in a semi-recumbent position; pre-dose (prior 
to the APR-246 PK blood draw before the infusion) and at the EOI, per Table 6 
• 
APR-246 administration: Days 1–4 
• 
Blood sample for APR-246 pharmacokinetics: on Days 1, 2, 3 and 4, per Table 5 
• 
Pembrolizumab at a dose of 200 mg is to be administered on Day 3 ±1 day of each 
cycle before the Day 3 dose of APR-246 
 
7.2.1.2 Cycle 1 Days 8 and 15 (±3 Days)  
• 
Clinical toxicity assessment 
• 
Concomitant medications review 
• 
Hematology, including complete blood count with white blood cell differential  
• 
Serum chemistry, including sodium, potassium, chloride, CO2, BUN, creatinine, 
glucose, calcium, albumin, total protein, total bilirubin, AST, ALT, alkaline 
phosphatase, TSH and free T4 
 
7.2.2 Cycle 2 and Onwards (Cycle 3+) Day 1 (±3 Days) 
These tests should be performed prior to first dose 
• 
Clinical toxicity assessment 
• 
Concomitant medications review 
• 
Physical examination: Day 1*  

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• 
Weight  
• 
ECOG performance status (Day 1;  APPENDIX II) 
• 
Vital signs 
• 
APR-246 administration: Days 1–4 
• 
Hematology (Day 1*), including complete blood count with white blood cell differential 
• 
Serum chemistry (Day 1*), including sodium, potassium, chloride, CO2, BUN, 
creatinine, glucose, calcium, albumin, total protein, total bilirubin, AST, ALT, alkaline 
phosphatase, TSH and free T4 
• 
Blood for biomarkers (Cycle 2) 
• 
Blood for PBMC (Cycle 2 and Cycle 5) 
• 
Fresh tissue biopsy 
• 
ECG: standard 12-lead ECGs with subject in semi-recumbent position before APR-246 
infusion on Day 1 see Table 6 
• 
Cycle 3 and onwards, prior to each odd cycle: disease assessment  
 
7.2.2.1 Cycle 2 and Onwards Days 2–4  
• 
Clinical toxicity assessment 
• 
Concomitant medications review 
• 
Vital signs, including blood pressure, heart rate, respiration rate and temperature, 
collected 2 hours into APR-246 infusion (± 30 min) and at EOI (± 30 min) 
• 
Pembrolizumab at a dose of 200 mg is to be administered on Day 3 ±1 day of each 
cycle before the Day 3 dose of APR-246 
• 
APR-246 administration: Days 1–4 
• 
Only Cycle 3: Blood sample for APR-246 pharmacokinetics: on Days 1, 2, 3 and 4, per 
Table 5 
 
 
7.3 
End of Treatment Visit 
This visit should take place 30 days after the last dose of study treatment, if treatment is 
stopped early for any reasons.   
 
• 
Physical examination 
• 
Weight  
• 
Vital signs 
• 
Disease assessment 
• 
ECOG performance status (APPENDIX II) 
• 
Hematology, including complete blood count with white blood cell differential 
• 
Serum chemistry, including sodium, potassium, chloride, CO2, BUN, creatinine, 
glucose, calcium, albumin, total protein, total bilirubin, AST, ALT, alkaline 
phosphatase, TSH and free T4 
• 
Blood for biomarkers 

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• 
Blood for PBMC 
• 
Clinical toxicity assessment up to 30 days after the last dose 
• 
Survival follow-up 
 
7.4 
Long-Term Follow-Up 
Long-term follow-up can be done remotely (e.g. via telephone, via local practitioner or via 
review of medical records). After a subject is removed or withdrawn from the study, the 
subject will be followed for 1 year or until death, whichever occurs first. Off-treatment data 
on OS will be updated every 6 months or until death, whichever occurs first. If a subject is 
removed from the study due to unacceptable AEs, the event(s) will be followed until 
resolution or stabilization of the AE(s). Subjects who respond and discontinue study 
treatment for reasons other than PD should have response assessments and survival should 
be collected every 2 months until disease progression or death, whichever occurs first. After 
disease progression, data for survival should be collected every 6 months until death. 
 
8.0 STUDY ASSESSMENTS 
8.1 
Safety Assessments 
8.1.1 Safety Analysis 
Safety data will be tabulated for all subjects and include vital signs, laboratory parameters, 
and AEs. 
 
8.1.2 Reporting of Adverse Events 
8.1.2.1 Adverse Events 
An AE is any untoward medical occurrence in a subject or clinical investigation subject 
administered a pharmaceutical product that does not necessarily have a causal relationship 
with the treatment. An AE can be any unfavorable and unintended sign (including a 
laboratory finding), symptom or disease temporally associated with the use of a medicinal 
(investigational) product, whether or not related to the medicinal (investigational) product.  
 
The AE reporting period starts at study treatment initiation. At each evaluation, subjects 
should be interviewed in a non-directed manner to elicit potential adverse reactions from 
the subject. The occurrence of an AE will be based on changes in the subject’s physical 
examination, laboratory results, and/or signs and symptoms. 
 
All AEs (except Grade 1 and 2 laboratory abnormalities that do not require an intervention), 
regardless of causal relationship, are to be recorded in the eCRF and source documentation. 
The investigator must determine the intensity of any AEs according to the NCI-CTCAE version 

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5.0 and their causal relationship. Those AEs not covered by these criteria will be graded as 
follows:  
 
1. 
Mild: Discomfort noticed, but no disruption of normal daily activity. Prescription drug 
not ordinarily needed for relief of symptom but may be given because of personality 
of subject. 
2. 
Moderate: Discomfort sufficient to reduce or affect normal daily activity. Subject is 
able to continue in study; treatment for symptom may be needed. 
3. 
Severe: Incapacitating, severe discomfort with inability to work or to perform normal 
daily activity. Severity may cause cessation of treatment with test drug; treatment for 
symptom may be given and/or subject hospitalized. 
4. 
Life-Threatening: Symptom(s) place the subject at immediate risk of death from the 
reaction as it occurred; it does not include a reaction that, had it occurred in a more 
serious from, might have caused death. 
5.  
Fatal: Event caused the death of the subject.  
 
AEs will be followed until resolution or stabilization while the subject remains on-study. Once 
the subject is removed from study, events thought to be related to the study medication will 
be followed until resolution or stabilization, unless, in the investigator’s opinion the event is 
unlikely to resolve due to the subject’s underlying disease, or until the subject starts a new 
treatment regimen or the subject is lost to follow-up. 
 
8.1.2.2 Attribution Definitions 
The relationship of each AE to study treatment should be evaluated by the Investigator using 
the following criteria: 
 
Definitely related: A clinical event, including laboratory test abnormality, occurring in a 
plausible time relationship to the medication administration, and which cannot be explained 
by concurrent disease or other drugs or chemicals. The response to withdrawal of the drug 
should be clinically plausible.  
 
Possibly related: A clinical event, including laboratory test abnormality, with a reasonable 
time sequence to the medication administration, but which could also be explained by 
concurrent disease or other drugs of chemicals. Information on the drug withdrawal may be 
lacking or unclear.  
 
Unlikely related: A clinical event, including laboratory test abnormality, with a little or no 
temporal relationship to medication administration, and which other drugs, chemicals or 
underlying disease provide plausible explanations.  
 
Not related: A clinical event, including laboratory test abnormality that has no temporal 
relationship to the medication or has more likely alternative etiology. 

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8.1.2.3 Definition of an Unexpected Adverse Event 
An unexpected AE is defined as any adverse drug experience, the specificity or severity of 
which is not consistent with the current IB; or, if an IB is not available, the specificity or 
severity of which is not consistent with the risk information described in this protocol or in 
the regulatory agency study authorization application.   
 
Unexpected, as used in this definition, refers to an adverse drug experience that has not 
been previously observed (e.g., included in the IB) rather than from the perspective of such 
experience not being anticipated from the pharmacological properties of the pharmaceutical 
product. 
 
8.1.2.4 Serious Adverse Event (SAE) 
An SAE is defined as any untoward medical occurrence that at any dose: 
 
1. 
Results in death, 
2. 
Is life-threatening (i.e., the subject was at risk of death at the time of the event. It does 
not refer to an event which hypothetically might have caused death if it was more 
severe), 
3. 
Requires inpatient hospitalization or prolongation of existing hospitalization 
excluding that for pain management, disease staging/re-staging procedures, or 
catheter placement unless associated with other serious events, 
4. 
Results in persistent or significant disability/incapacity, or 
5. 
Is a congenital anomaly/birth defect. 
 
Important medical events that may not result in death, be life-threatening, or require 
hospitalization may be considered serious adverse drug events when, based on appropriate 
medical judgment, they may jeopardize the subject and may require medical or surgical 
intervention to prevent one of the outcomes listed above. 
 
8.1.2.5 Pregnancy 
Any pregnancy detected during the study, or that occurs within 30 days after stopping study 
medication, must be reported immediately to the investigator. Pregnancy, in and of itself, is 
not regarded as an AE, unless there is suspicion that study medication may have interfered 
with the effectiveness of a contraceptive medication. If the subject becomes pregnant while 
on-study, the study drug should be immediately discontinued. Pregnancy information about 
a female subject or a female partner of a male subject should be reported immediately from 
the time the investigator first becomes aware of a pregnancy or its outcome. This will be 
performed by the investigator per instructions from the Sponsor’s monitoring CRO.  
 

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Any pregnancy complication, spontaneous abortion, elective termination of a pregnancy for 
medical reasons, outcome of stillbirth, congenital anomaly/birth defect, or SAE in the mother 
will be recorded as an SAE and will be reported as described in Section 8.1.2.6.  
 
8.1.2.6 Reporting of Serious Adverse Events 
AEs classified as serious require expeditious handling and reporting to Sponsor’s monitoring 
CRO to comply with regulatory requirements. 
 
For any SAE that occurs while a subject is on-study; within 30 days of the last study treatment 
administration, regardless of any opinion as to the relationship of the SAE to the study 
treatment; or if any SAE that the investigator feels is related to the study treatment occurs 
later than 30 days after the last study treatment administration, the Sponsor’s monitoring 
CRO must be notified immediately (within 24 hours of becoming aware of the event) by 
email, fax or telephone. Notification by email is preferred. The email address, fax and 
telephone numbers listed below may be used during both business and non-business hours. 
During non-business hours a recorded message will provide the telephone caller with the 
contact information for the on-call monitor. 
 
All SAEs require that a Serious Adverse Event Report Form be completed and forwarded 
either via facsimile or as a PDF via email to Sponsor’s monitoring CRO at the fax number or 
email listed below within 24 hours of becoming aware of the event.  
 
SAEs will be reported to: 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
8.1.2.7 Safety Monitoring Plan  
The Medical Monitor is responsible for ongoing safety monitoring for the study per the 
detailed safety plan. This monitoring will include a review of all SAEs as they are reported by 
the study site. The Medical Monitor will also be in contact with site monitors and will be 
available to discuss any issues concerning safety with site staff. Safety data will be reviewed 
periodically by the 
 and the Sponsor’s Medical Officer. 
 
DRT consisting of the Medical Monitor, Site Principal Investigators, and other clinical research 
personnel that the Sponsor may deem appropriate, will hold DRMs on an interim basis at a 
frequency dependent on study accrual. At these meetings, the DRT will review AEs and DLTs 
and make recommendations regarding the RP2D. In the expansion portion of the study, the 
DRT will evaluate safety and tolerability after 5 subjects have completed 1 cycle of treatment 
in each cohort. All accumulated safety data will be discussed during DRMs. 

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The DRT will produce summaries or minutes of these meetings. These summaries will be 
available for inspection when requested by any of the regulatory bodies charged with the 
safety of human subjects and the integrity of data. 
 
8.2 
Efficacy Assessments 
Tumor assessments will be performed by the investigators based on RECIST 1.1, which will 
also guide treatment decisions. All scans for tumor assessments performed during the study 
should be archived in accordance with the standard local practice. The scans must be 
accessible in the event of a Sponsor request to submit them for central review. 
Tumor assessments will be carried out every 9 weeks (±3 days) after initiating study 
treatment, prior to initiation of each odd treatment cycle starting at Week 9, then every 6 
weeks through the first year and then every 9 weeks, thereafter. CT/MRI scans of chest, 
abdomen, and pelvis and of other known sites of disease will be obtained at screening (within 
28 days prior to Cycle 1 Day 1), at all tumor assessment time points, and as indicated 
clinically. Color photographs containing a millimeter scale must be taken of all skin lesions 
being used as target lesions. Historical standard of care scans that are performed with 
scanning parameters consistent with the requirements for this protocol within 28 days prior 
to dosing are acceptable. Subjects with squamous cell carcinoma of the head and neck must 
also have head and neck scans performed. 
MRI may be used instead of CT for head, neck, abdomen, and pelvis; however, the chest must 
be assessed using CT. Chest disease may not be followed using chest x-ray. PET scanning 
should not be used, but PET/CT may be used if CT component is with contrast enhancement 
and of diagnostic quality. 
A brain scan (CT with contrast or MRI pre- and post-gadolinium) must be performed at 
screening to assess potential CNS disease and/or metastases for patients with predilections 
to develop CNS metastases. For subjects with previously treated eligible brain metastases, a 
brain scan must be performed at all tumor assessment time points. For all subjects, a follow-
up brain scan must be performed to confirm CR within 1 week of response confirmation, or 
if clinically indicated. 
The tumor assessment schedule should not be affected by interruptions in study treatment. 
Subjects taken off study treatment without disease progression will also undergo tumor 
assessments per the Study Calendar (Table 4) until disease progression is documented or 
another anticancer therapy is initiated. 
The same method of assessment must be used at all time points as was used at screening. 
Throughout the study it is critical that the same imaging methodology be applied, and 
contrast be consistently provided unless IV contrast becomes medically contraindicated 
during the course of treatment or the dose of contrast needs to be adjusted based on the 
subject’s health status. 

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In order for SD to be considered the BOR, it must occur ≥ 5 weeks following the first dose of 
study drug. 
The first radiological assessment of tumor response status will be performed at Week 9 (±3 
days), unless there is clinical indication warranting earlier radiologic imaging. If imaging at 
Week 9 shows SD, treatment will be continued and tumor assessments will be conducted at 
the next regularly scheduled imaging time point, i.e., every 6 weeks through the first year, 
then every 9 weeks, thereafter. Responses (PR or CR) should be confirmed no less than 4 
weeks after the initial response, but generally at the next scheduled tumor assessment time 
point. 
 
If the time point tumor assessment is PD, treatment may be continued and tumor 
assessments be repeated at least 4 weeks later, but generally at the next scheduled tumor 
assessment time point in order to confirm PD. If repeat imaging shows a reduction in the 
tumor burden compared to the initial tumor assessment demonstrating PD, treatment may 
be continued as per treatment schedule. If repeat imaging confirms PD, subjects will be 
considered for discontinuation from study treatment. In determining the tumor time point 
response, investigators should consider all target lesions as well as non-target lesions and 
new lesions. The decision to continue study treatment after the first evidence of PD is at the 
investigator’s discretion based on the clinical status of the subject. However, subjects may 
continue to receive study treatment in the setting of PD if they are deriving clinical benefit in 
the opinion of the investigator. 
Subjects may continue receiving study treatment while waiting for confirmation of PD if they 
are clinically stable as defined by the following criteria: 
• 
Absence of signs and symptoms (including worsening of laboratory values) indicating 
disease progression 
• 
No decline in ECOG performance status 
• 
Absence of rapid progression of disease 
• 
Absence of progressive tumor at critical anatomical sites (e.g., cord compression) 
requiring urgent alternative medical intervention 
If PD is confirmed and the subject is experiencing clinical benefit, the site may continue study 
treatment. 
 
8.2.1 Objective Response Rate 
ORR is defined as the proportion of subjects who have BOR of CR or PR as measured by 
RECIST 1.1 (see APPENDIX V). 
 
ORR is measured from the start date of the treatment period until date of death from any 
cause. Subjects who are lost to follow-up and the subjects who are alive at the date of data 
cutoff will be censored at the date the subject was last known alive. 
 

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8.2.2 Disease Control Rate 
DCR is defined as the proportion of subjects who have BOR of CR or PR or SD (duration of 
SD ≥ 5 weeks). 
 
8.2.3 Duration of Response 
DOR is defined as the duration of CR or PR. 
 
8.2.4 Durable Stable Disease Rate 
Durable SD rate is defined as the proportion of subjects whose BOR is SD and the duration 
of SD is ≥ 23 weeks. 
 
8.2.5 Clinical Benefit Rate 
CBR is defined as the proportion of subjects who have BOR of CR or PR or durable SD 
(duration of SD ≥ 23 weeks). 
 
8.3 
Progression-Free Survival (PFS) 
PFS is defined as the time from the first study dose date to the date of first documentation of 
confirmed disease progression or death (whichever occurs first). 
 
8.4 
Overall Survival 
OS is measured from the date of initiating study treatment to the date of death. 
 
8.5 
Pharmacokinetics  
Plasma concentrations of APR-246 will be measured in Cycle 1 and again in Cycle 3, at the 
timepoints provided in Table 5.  
Table 5. PK Blood Sampling Timepoints for APR-246 in Cycle 1 and Cycle 3 
APR-246 plasma collection timepoints 
a 
D1 
D2 
D3 
D4 
Prior to APR-246 infusion 
× 
× 
× 
× 
At the end of APR-246 infusion 
× 
 
× 
 
1 hour after the end of APR-246 infusion 
× 
 
× 
 
3 hours after the end of APR-246 
infusion 
× 
 
 
 
a A window of ±15 min applies to each time point. 

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The data will be evaluated using population pharmacokinetics (see section below). 
8.6 
Electrocardiographic Assessment 
Table 6 describes the routine ECG requirements from screening through Cycle 4: 
Table 6. ECG Assessment Requirements 
Time Point 
ECG, number 
Timing 
Baseline/Screening Triplicate 
Must be within 28 days of C1D1 
Cycle 1, Days 1-4 
Triplicate 
Pre-dose; Post dose (at the end of infusion; ± 10 
min)  
Cycles 2+, Day 1 
Triplicate 
Pre-dose 
 
If repeated QTcF measurements show a stable QTcF < 450 msec, or if QTcF remains stable 
within the interval of 450 – 469 msec with no significant change at the EOI during several 
cycles of treatment, reducing the number of ECGs performed in the study may be discussed 
with the Medical Monitor. 
If a subject starts treatment with another medication known to prolong QT interval at any 
time during the study therapy, an additional pre- and post-dose (6 hours after start of 
infusion, ± 30 min) ECG should be performed on the next treatment day. 
Please consult Section 6.3.1 for additional requirements for proceeding with treatment with 
APR-246. 
8.7 
Correlative Studies 
Blood and serum biomarkers 
Peripheral blood samples will be collected at specified time points for all enrolled subjects. 
Peripheral blood mononuclear cells (PBMCs) will be isolated and stored for future flow 
cytometry analyses. Serum samples will be stored for future cytokine analyses. 
Archived, formalin-fixed paraffin-embedded (FFPE) tissue 
Optional archived FFPE tumor tissue samples will be collected from all subjects for potential 
assessment of mutations and other genetic alterations and/or proteins including PD-1/PD-L1 
status and other relevant biomarkers (e.g., tumor infiltrating lymphocytes, T cell repertoire, 
ribonucleic acid [RNA] signature profiles) which may be important in the development and 
progression of cancer as well as for potential use in diagnostic development. Appropriate 
technology/methodologies will be used based on the amount of tumor tissue available. 
Fresh tissue 
For all tumor types, optional fresh tumor biopsies will be collected at baseline and on 
treatment to examine markers of target engagement, relevant pharmacodynamic 
biomarkers, and potential markers of response. Fresh biopsies should be limited to readily 

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accessible tumor lesions (e.g., skin, peripheral lymph nodes, liver metastases that can be 
readily accessed using CT guidance). Subjects should have the biopsy before administration 
of the first dose of study drug and at a time point 3 weeks after the first dose (if they have 
recovered adequately from the biopsy taken prior to starting therapy).  
Instructions for the processing, storage, and shipping of samples will be provided in the 
Laboratory Manual. 
Pharmacokinetic-Pharmacodynamic Analyses: 
Data from both safety lead-in and exploratory portions of the study will be used to explore 
PK/PD relationships for effects of APR-246 in combination with pembrolizumab on ORR, 
other efficacy-related parameters including PFS and OS, AEs/dose reductions, and Phase 2 
blood and tumor biomarkers. Exploratory/graphical analyses will be conducted for PK/PD 
evaluations and may be followed by model-based analyses. 
 
9.0 STATISTICS 
9.1 
Sample Size 
In the safety lead-in portion of the study, up to 18 DLT-evaluable patients will be enrolled to 
determine the RP2D. 
The dose expansion consists of 3 cohorts. The ORRs to pembrolizumab for the patients with 
the 3 types of cancer, who were R/R to previous chemotherapies, were 21.1% and 22,7% for 
urothelial cancer and gastric/GEJ adenocarcinoma, respectively. The ORR for patients with 
advanced NSCLC who have previously been treated with anti-PD-1/PD-L1 therapy is expected 
to be negligible (i.e. <= 20%). As such, the expected response rate to the combination therapy 
across indications is 20% to 30%. In order to increase the estimate precision, at least 
20 evaluable patients will be included in each of the 3 cohorts. 
Table 7 summarizes the 95% CI of response rates of 20% and 30% by the sample size. For 
example, if the sample size is 20 patients, at least 2 responders are needed to be over the 
lower boundary of 95% CI of 20% response rate.  
Table 7. 2-sided 95% Confidence Interval for the ORR of 20% and 30% (20, 30 and 40 
sample sizes) 
 
95% CI for 20% ORR  
95% CI for 30% ORR 
N=20 
(5.7%, 43.7%) 
(11.9%, 54.3%) 
N=30 
(7.7 %, 38.6%) 
(14.7 %, 49.4%) 
N=40 
(9.1 %, 35,6%) 
(16.6 %, 46.5%) 
 

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9.2 
Analysis Populations 
Safety population: Subjects will be evaluable for safety if they receive at least one dose of 
APR-246. The safety population will be used to summarize exposure and safety parameters. 
DLT-evaluable population: All subjects who either experience a DLT during first the 3 weeks 
(Cycle 1) of the study treatment or receive ≥ 75 % of scheduled Cycle 1 dose of APR-246 in 
combination with pembrolizumab and do not experience a DLT. Any individual subject who 
is not evaluable for DLT will be replaced by a new subject through additional subject 
enrollment. 
Efficacy evaluable (EE) population: All subjects who complete at least one treatment cycle of 
APR-246 in combination with pembrolizumab and who have at least one post-treatment 
clinical response assessment. Subjects who fail to complete one treatment cycle will also be 
considered EE if they show clear evidence of clinically significant disease progression. The EE 
population will be the secondary analysis population for efficacy. 
PK population: Subjects will be evaluable for PK if at least one post-dose sample for PK 
evaluation has been obtained.  
 
PK/Pharmacodynamic population: All subjects who receive at least 1 dose of study drug (APR-
246 pembrolizumab) and have evaluable pharmacodynamic and concentration data. 
 
9.3 
Data Summaries 
Generally, all the continuous variables will be summarized using n (number of subjects with 
available data), mean, standard deviation (StDev), median, and range (minimum and 
maximum). Categorical data will be summarized by frequency and percentage. Time to event 
data will be analyzed using Kaplan-Meier method, and the number and percentage of events, 
or censored, the first quartile at 25%, median with 95% confidence, and third quartile at 75% 
of survival time will be presented. The survival rate at the 3, 6, 9, and 12 months, and then 2, 
3 and 5 years will be presented. All the study data will be listed. 
The following general study data, demographic, baseline characteristics and disease history 
will be summarized: 
• 
Subject disposition 
• 
Protocol deviation 
• 
Demographics 
• 
Cancer disease diagnosis and history 
• 
Prior cancer treatments 
• 
Medical history 
• 
Prior/concomitant medications 
 

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Safety data including AEs, vital signs, laboratory data, ECG, physical exam, ad ECOG 
performance status will be summarized in the safety population. AEs will be coded using 
MedDRA and graded using NCI-CTCAE v5.0 severity grade. 
 
The efficacy endpoints in the safety lead-in portion will be listed only. In the expansion phase, 
all the rates will be summarized with 95% exact CI (Clopper and Pearson) by cohorts. The 
time to event data will be analyzed using Kaplan-Meier method and the corresponding 
survival plots will be produced.  
 
To assess any DDI between APR-246 and pembrolizumab, the primary PK parameters of 
APR-246 will be compared graphically and via descriptive statistics with historical data using 
the PK analysis set. If warranted, additional analyses may be performed. A popPK model for 
APR-246 will be developed. The model will be parameterized in terms of CL and Vd. 
 
The effect of APR-246-pembrolizumab combination therapy on soluble, tissue, genetic 
and/or imaging biomarkers will be summarized using descriptive statistics using the 
PK/pharmacodynamic analysis set. PK/pharmacodynamic relationships will be explored 
graphically and may be investigated by model-based analyses. 
 
Descriptive statistics/results from exploratory molecular analyses will be written and may 
include but are not limited to: TP53 variant allele frequency by next-generation sequencing 
(NGS), p53 immunohistochemistry, mutations in other genes by NGS, RNA expression.  
 
9.4 
Pharmacokinetic Analysis 
Pharmacokinetic Analysis 
The DDI between APR-246 and pembrolizumab will be evaluated using popPK methods. The 
existing popPK model for APR-246 will be used to compare the observed plasma 
concentrations of APR-246 in presence of pembrolizumab with the predicted plasma 
concentrations assuming no DDI (visual predictive check). Additionally, the PK analysis 
dataset from this study will be integrated with the existing popPK dataset and the effect of 
pembrolizumab on APR-246 PK parameters will be tested as covariate in the model. 
 
Pharmacodynamic Analysis 
The effect of APR-246-pembrolizumab combination therapy on soluble, tissue, genetic 
and/or imaging biomarkers will be summarized using descriptive statistics using the 
PK/pharmacodynamic analysis set. PK/pharmacodynamic relationships will be explored 
graphically and may be investigated by model-based analyses. 
 
 

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10.0 QUALITY CONTROL AND QUALITY ASSURANCE PROCEDURES 
10.1 Monitoring of the Study and Regulatory Compliance 
The project manager, or designee, will make an initiation site visit to each institution to 
review the protocol and its requirements with the investigator(s), inspect the drug storage 
area, fully inform the investigator of his/her responsibilities and the procedures for assuring 
adequate and correct documentation. During the initiation site visit the eCRFs will be 
reviewed. Other pertinent study materials will also be reviewed with the investigator’s 
research staff. During the course of the study, the monitor will make regular site visits in 
order to review protocol compliance, examine eCRFs and individual subject’s medical records 
and assure that the study is being conducted according to pertinent regulatory 
requirements. All eCRF entries will be verified with source documentation. The review of 
medical records will be done in a manner to assure that subject confidentiality is maintained.  
 
10.2 Curricula Vitae and Financial Disclosure of Investigators  
All Principal Investigators will be required to provide a current signed and dated curriculum 
vitae, a completed FDA Form 1572 and a financial disclosure statement to Sponsor’s 
monitoring CRO. All Sub-Investigators will be required to provide a current curriculum vitae 
and a financial disclosure statement to Sponsor’s monitoring CRO. 
 
10.3 Protocol Modifications 
No modification of the protocol should be implemented without the prior written approval 
of the Sponsor or the Sponsor’s representative. Any such changes which may affect a 
subject’s treatment or informed consent, especially those increasing potential risks, must 
receive prior approval by the IRB/IEC. The exception to this is where modifications are 
necessary to eliminate an immediate hazard to trial subjects, or when the change involves 
only logistical or administrative aspects of the trial (e.g., change in monitor, change in 
telephone number). Other administrative revisions which may impact the clinical portion of 
a study will be duly reported to the IRB/IEC by the Principal Investigator. 
 
10.4 Publication Policy 
The publication of the results of the study will be subject to the terms and conditions of the 
clinical trial agreement between the Sponsor and Investigators. Sponsor approval is required 
for publication of any data from this trial.  
 

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11.0 ETHICAL CONSIDERATIONS 
11.1 Informed Consent 
The investigator will obtain written informed consent from each subject, or their authorized 
representative, participating in the study. The form must be signed, witnessed and dated. 
The ICF will contain all the Essential Elements of Informed Consent set forth in 21 CFR, 
Part 50, the European Union Directive 2001/20/EC and its associated Detailed Guidances, 
European Union GCP Directive 2005/28/EC, the ICH Guideline for GCP, Section 4.8, and the 
terms of the Declaration of Helsinki (2013). Copies of the signed document should be given 
to the subject and filed in the investigator’s study file, as well as the subject’s medical record 
if in conformance with the institution’s Standard Operating Procedures.  
 
11.2 Institutional Review Board/Independent Ethics Committee 
The study will not be initiated without approval of the appropriate IRB/IEC and compliance 
with all administrative requirements of the governing body of the institution. This protocol, 
consent procedures, and any amendments must be approved by the IRB/IEC in compliance 
with current regulations of the FDA and the European Union as applicable and in accordance 
with ICH/GCPs. A letter of approval will be sent to the Sponsor prior to initiation of the study 
and when any subsequent modifications are made. The IRB/IEC will be kept informed by the 
investigator, Sponsor’s monitoring CRO or the Sponsor, as required by national regulations, 
as to the progress of the study as well as to any serious and unexpected AEs.  
 
11.3 Subject Privacy  
In order to maintain subject confidentiality, all eCRFs, study reports and communications 
relating to the study will identify subjects by initials and assigned subject numbers; subjects 
should not be identified by name. In accordance with local, national or federal regulations, 
the investigator will allow the Sponsor or designee personnel access to all pertinent medical 
records in order to verify the data gathered on the eCRFs and to audit the data collection 
process. Regulatory agencies such as the U.S. FDA may also request access to all study 
records, including source documentation for inspection. Clinical information will not be 
released without the written permission of the subject as outlined in the subject consent 
form. 
 
12.0 DATA HANDLING AND RECORD KEEPING 
12.1 Data to be Entered Directly in the electronic Case Report Form 
The eCRF will be the source record. 
 

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12.2 Recording of Data 
Data collected during the study will be entered in the subject’s eCRF by the investigational 
site staff. The staff will keep records of the subject’s visit in the files considered as source 
documents for the site, e.g., hospital chart, research chart. The investigator will be 
responsible for the recording of all data on the eCRF and for submitting the data to the 
Sponsor or their designee in a timely manner. Should any value be significantly different 
from normal, the investigator will comment in the appropriate sections provided in the eCRF.  
The investigator will provide access to his/her original records to permit a representative 
from the Sponsor to verify the proper transcription of data.  
 
12.3 Study Records 
U.S. Federal laws require that an investigator maintain all study records for the indication 
under investigation for two years following the date a Product Licensing Application is 
approved or, if no application is to be filed or if the application is not approved for such 
indication, until two years after the investigation is discontinued and the FDA is notified. 
 
 

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13.0 REFERENCES 
1.  
Aprea Therapeutics. APR-246 Investigator’s Brochure v10.1. 2019:168. 
2.  
Lehmann S, Bykov VJN, Ali D, et al. Targeting p53 in Vivo: A First-in-Human Study With 
p53-Targeting Compound APR-246 in Refractory Hematologic Malignancies and 
Prostate Cancer. J Clin Oncol. 2012;30(29):3633-3639. doi:10.1200/JCO.2011.40.7783 
3.  
European Medicines Agency. ICH E9 (R1) addendum on estimands and sensitivity 
analysis in clinical trials to the guideline on statistical principles for clinical trials - 
Step 2b. 2017;44(August):1-23. 
4.  
Deneberg S, Cherif H, Lazarevic V, et al. An open-label phase I dose-finding study of 
APR-246 in hematological malignancies. Blood Cancer J. 2016;6(7):e447. 
doi:10.1038/bcj.2016.60 
5.  
Garon EB, Hellmann MD, Rizvi NA, et al. Five-year overall survival for patients with 
advanced non-small-cell lung cancer treated with pembrolizumab: Results from the 
phase i KEYNOTE-001 study. J Clin Oncol. 2019;37(28):2518-2527. 
doi:10.1200/JCO.19.00934 
6.  
Merck, Corp. S& D. Pembrolizumab Injection Highlights of Prescribing Information. 
2020. https://www.merck.com/product/usa/pi_circulars/k/keytruda/keytruda_pi.pdf. 
7.  
Sharma MD, Rodriguez PC, Koehn BH, et al. Activation of p53 in Immature Myeloid 
Precursor Cells Controls Differentiation into Ly6c+CD103+ Monocytic Antigen-
Presenting Cells in Tumors. Immunity. 2018;48(1):91-106.e6. 
doi:10.1016/j.immuni.2017.12.014 
8.  
Ghosh A, Richardson CA. Abstract 2571: Role of XRCC4 downregulation in 
bioflavonoid-induced chromosomal translocations. In: Molecular and Cellular Biology / 
Genetics. American Association for Cancer Research; 2019:2571-2571. 
doi:10.1158/1538-7445.AM2019-2571 
9.  
Roselló S, Blasco I, García Fabregat L, Cervantes A, Jordan K, ESMO Guidelines 
Committee. Management of infusion reactions to systemic anticancer therapy: ESMO 
Clinical Practice Guidelines†. Ann Oncol. 2017;28(suppl_4):iv100-iv118. 
doi:10.1093/annonc/mdx216 
10.  
Eisenhauer EA, Therasse P, Bogaerts J, et al. New response evaluation criteria in solid 
tumours: Revised RECIST guideline (version 1.1). Eur J Cancer. 2009;45(2):228-247. 
doi:10.1016/j.ejca.2008.10.026 
11.  
Seymour L, Bogaerts J, Perrone A, et al. iRECIST: guidelines for response criteria for 
use in trials testing immunotherapeutics. Lancet Oncol. 2017;18(3):e143-e152. 

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doi:10.1016/S1470-2045(17)30074-8 
 

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APPENDIX I - Cockcroft-Gault Equation 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Males: 
 
 
Creatinine CL 
(mL/min) 
= 
Weight (kg) × (140 – Age) 
72 × serum creatinine (mg/dL) 
Females: 
 
 
Creatinine CL 
(mL/min) 
= 
Weight (kg) × (140 – Age)  
× 0.85 
72 × serum creatinine (mg/dL) 

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APPENDIX II - ECOG Performance Status 
 
 
 
       Grade 
 
 
0 
 
Fully active, able to carry on all pre-disease performance without 
restriction. 
 
 
1 
 
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 
 
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 
 
Capable of only limited self-care, confined to bed or chair more 
than 50% of waking hours. 
 
 
4 
 
Completely disabled. Cannot carry on any self-care. Totally 
confined to bed or chair. 
 
 
5 
 
Dead. 
 
 
 
 

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APPENDIX III - Acceptable Contraceptive Methods 
● Male or female condom with or without spermicide 
● Cervical cap, diaphragm or sponge with spermicide 
Highly Effective Contraceptive Methods That Are User Dependent a  
Failure rate of <1% per year when used consistently and correctly. 
● Combined (estrogen- and progesterone-containing) hormonal contraception b 
○ Oral  
○ Intravaginal  
○ Transdermal  
○ Injectable 
● Progestogen-only hormonal contraception b 
○ Oral  
○ Injectable  
Highly Effective Methods That Have Low User Dependency  
Failure rate of <1% per year when used consistently and correctly. 
● Progesterone-only contraceptive implant b, c  
● Intrauterine hormone-releasing system (IUS) b  
● Intrauterine device (IUD) 
● Bilateral tubal occlusion 
● Vasectomized partner  
A vasectomized partner is a highly effective contraception method provided that the 
partner is the sole male sexual partner of the female of childbearing potential and the 
absence of sperm has been confirmed. If not, an additional highly effective method of 
contraception should be used.  
● Sexual abstinence  
Sexual abstinence is considered a highly effective method only if defined as refraining 
from heterosexual intercourse during the entire period of risk associated with the study 
treatment. (The reliability of sexual abstinence needs to be evaluated in relation to the 
duration of the study and the preferred and usual lifestyle of the participant.)  
Notes:  
Use should be consistent with local regulations regarding the use of contraceptive 
methods for participants of clinical studies. 
a) Typical use failure rates are lower than perfect-use failure rates (i.e., when used 
consistently and correctly).  
b) If hormonal contraception efficacy is potentially decreased due to interaction with 
study treatment, condoms must be used in addition to the hormonal contraception 
during the treatment period and for at least 120 days, (corresponding to time needed to 

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eliminate study treatment plus 30 days for study treatments with genotoxic potential) 
after the last dose of the study treatment. 
c) If locally required, in accordance with Clinical Trial Facilitation Group (CTFG) guidelines, 
acceptable hormonal contraceptives are limited to those which inhibit ovulation.  
 
 
 

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APPENDIX IV - New York Heart Association (NYHA) Classification 
 
NYHA Grading 
MET* 
Class I 
No limitations. Ordinary physical activity does not 
cause undue fatigue, dyspnea or palpitations 
(asymptomatic LV dysfunction) 
>7 
Class II 
Slight limitation of physical activity. Ordinary physical 
activity results in fatigue, palpitation, dyspnea or 
angina pectoris (mild Congestive Heart Failure (CHF)). 
5 
Class III 
Marked limitation of physical activity. Less than 
ordinary physical activity leads to symptoms 
(moderate CHF) 
2 – 3 
Class IV 
Unable to carry on any physical activity without 
discomfort. Symptoms of CHF present at rest (severe 
CHF). 
1.6 
 
*MET (metabolic equivalent) is defined as the resting VO2 for a 40-year-old 70kg man.  
1 MET = 3.5 mL O2/min/kg body weight. 
 
 
 
 
 
 

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APPENDIX V - Tumor Measurement Based on RECIST 1.1 
See the international criteria proposed by the RECIST Committee, version 1.110 for 
additional details on RECIST1.1. 
 
Measurable disease will be defined as the presence of at least one measurable lesion 
that can be accurately measured in at least one dimension with the LD a minimum 
size of: 
• 
> 10mm by CT scan (CT scan slice thickness no greater than 5 mm) 
• 
10mm caliper measurement by clinical exam (lesions which cannot be 
accurately measured with calipers should be recorded as non-
measurable). 
• 
20 mm by chest x-ray. 
 
For malignant lymph nodes to be considered pathologically enlarged and 
measurable, a lymph node must be ≥ 15mm in short axis when assessed by CT scan 
(CT scan slice thickness recommended to be no greater than 5mm). At baseline and 
in follow-up, only the short axis will be measured and followed.   
 
All other lesions, including small lesions (LD < 10 mm or pathological lymph nodes 
with ≥ 10 to < 15 mm short axis) as well as truly non-measurable lesions, will be 
considered non-measurable.  Lesions considered truly non-measurable include: 
leptomeningeal disease; ascites; pleural/pericardial effusion; inflammatory breast 
disease; lymphangitic involvement of skin or lung, abdominal masses/abdominal 
organomegaly identified by physical exam that is not measurable by reproducible 
imaging techniques. 
 
All measurements should be recorded in metric notation, using calipers if clinically 
assessed. All baseline evaluations should be performed as close as possible to the 
treatment start and never more than 4 weeks before the beginning of the treatment.  
The same method of assessment and the same technique should be used to 
characterize each identified and reported lesion at baseline and during follow-up.  
Imaging based evaluation should always be done rather than clinical examination 
unless the lesion(s) being followed cannot be imaged but are assessable by clinical 
exam.  Clinical lesions will only be considered measurable when they are superficial 
and ≥10 mm diameter as assessed using calipers (e.g. skin nodules). For the case of 
skin lesions, documentation by color photography including a ruler to estimate the 
size of the lesions is recommended. 
 
Baseline Documentation of Target and Non-Target Lesions 

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All measurable lesions up to a maximum of 5 lesions total (and a maximum of two 
lesions per organ) representative of all involved organs should be identified as target 
lesions and will be recorded and measured at baseline.   
 
Target lesions should be selected on the basis of their size (lesions with the longer 
diameter), be representative of all involved organs, but in addition should be those 
that lend themselves to reproducible repeated measurements.  
 
A sum of the diameters (longest for non-nodal lesions, short axis for nodal lesions) 
for all target lesions will be calculated and reported as the baseline sum diameters. If 
lymph nodes are to be included in the sum, only the short axis is added into the sum. 
The baseline sum diameters will be used as reference to further characterize the 
objective tumor response of the measurable dimension of the disease. 
 
All other lesions (or sites of disease) including pathological lymph nodes should be 
identified as non-target lesions and should also be recorded at baseline. 
Measurements are not required, and these lesions should be followed as “present” 
or “absent”, or in rare cases “unequivocal progression”.   
 
Evaluation of Target Lesions using RECIST 1.1 Criteria 
NOTE: In addition to the information below, also see section 4.3.2 in the international 
criteria proposed by the RECIST Committee, version 1.110 for special notes on the 
assessment of target lesions.  
 
Complete response (CR) − Disappearance of all target lesions. Any pathological lymph 
node (LN) (whether target or non-target) must have decreased in short axis to < 10 
mm. 
 
Partial response (PR) − At least a 30% decrease in the sum of the LD of the target 
lesions taking as reference the baseline sum LD. 
 
Progressive Disease (PD) − At least a 20% increase in the sum of the LD of the target 
lesions taking as reference the smallest sum LD recorded since the treatment started 
including baseline if that is the smallest on study.  In addition to the relative increase 
of 20%, the sum must also demonstrate an absolute increase of at least 5mm.  The 
appearance of one or more new lesions also constitutes PD. 
 
Stable disease (SD) − Neither sufficient shrinkage to qualify for PR nor sufficient 
increase to qualify for PD taking as references the smallest sum LD since the 
treatment started. 
 

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Evaluation of Non-Target Lesions using RECIST 1.1 Criteria 
Complete response (CR) − Disappearance of all non-target lesions and normalization 
of tumor marker levels.  All LN must be non-pathological in size (< 10 mm short axis).   
 
Non-complete response (non-CR)/non-progression (non-PD) − Persistence of one or 
more non-target lesion(s) or/and maintenance of tumor marker level above the 
normal limits. 
 
Progressive disease (PD) − Appearance of one or more new lesions and/or 
unequivocal progression of existing non-target lesions. 
 
Evaluation of Best Overall Response using RECIST 1.1 Criteria 
The best overall response is the best response recorded from the start of the study 
treatment until the end of treatment provided the confirmation criteria are met.  To 
be assigned a status of PR or CR, changes in tumor measurements must be confirmed 
by repeat studies that should be performed > 4 weeks after the criteria for response 
are first met. If a CR/PR cannot be confirmed the original "response" should be 
considered stable disease. The best overall response will be defined according to the 
following table: 
 
Overall 
Response 
First 
Time 
Point 
Overall 
Response 
Subseque
nt Time 
Point 
BEST Overall Response 
CR 
CR 
CR 
CR 
PR 
SD, PD, or PR1 
CR 
SD 
SD provided minimum criteria for SD duration met, otherwise, 
PD 
CR 
PD 
SD provided minimum criteria for SD duration met, otherwise, 
PD 
CR 
NE2 
SD provided minimum criteria for SD duration met, otherwise, 
NE2 
PR 
CR 
PR 
PR 
PR 
PR 
PR 
SD 
SD 
PR 
PD 
SD provided minimum criteria for SD duration met, otherwise, 
PD 
PR 
NE2 
SD provided minimum criteria for SD duration met, otherwise, 
NE2 
NE 
NE2 
NE2 
1 If a CR is truly met at first time point, then any disease seen at a subsequent time point, even disease 
meeting PR criteria relative to baseline, makes the disease PD at that point (since disease must have 

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Protocol Number A20-11195  
Phase 1/2 Study of APR-246 in Combination with 
Pembrolizumab in Subjects with Solid Tumor Malignancies 
 
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reappeared after CR).  Best response would depend on whether minimum duration for SD was met.  
However, sometimes ‘CR’ may be claimed when subsequent scans suggest small lesions were likely still 
present and in fact the subject had PR, not CR at the first time point.  Under these circumstances, the 
original CR should be changed to PR and the best response is PR.  
 
2  NE=inevaluable