city of hope national medical
untitled h2

DEPARTMENT OF MEDICAL ONCOLOGY AND THERAPEUTICS RESEARCH
TITLE: COMBINING PEMBROLIZUMAB AND PALLIATIVE RADIOTHERAPY IN
GASTROESOPHAGEAL CANCER TO ENHANCE ANTI-TUMOR T CELL RESPONSE AND AUGMENT THE ABSCOPAL EFFECT
city of hope national medical
city of hope protocol number

| COH Initial Submission:                                | Protocol dated 04/08/2016   | Version: 00   |
|--------------------------------------------------------|-----------------------------|---------------|
| COH Amendment 01                                       | Protocol dated 02/10/2017   | Version: 01   |
| COH Amendment 02                                       | Protocol dated 07/26/2017   | Version: 02   |
| COH Amendment 03                                       | Title Page dated 02/27/2018 | Version: 03   |
| COH Amendment 04                                       | Protocol dated 10/16/2019   | Version: 04   |
| COH Amendment 05 at Cont.Protocol dated 10/16/2019(tp) | Packet: 05                  |               |  
DISEASE SITE: Esophageal, gastric, and gastroesophageal cancers STAGE (if applicable): IV MODALITY: Intravenous PHASE/TYPE: Phase II/Prospective biomarker analysis DIAGNOSTIC RADIOLOGIST: .  
| PRINCIPAL INVESTIGATOR:       | Joseph Chao, MD                                                   |
|-------------------------------|-------------------------------------------------------------------|
| COLLABORATING INVESTIGATOR(S) | Yi-Jen Chen, MD,                                                  |
| PARTICIPATING CLINICIANS:     | Vincent Chung, MD, Marwan Fakih, MD,  Daneng Li, MD, Dean Lim, MD |  
STUDY STATISTICIAN: Paul Frankel, PhD
EXTERNAL COLLABORATING INVESTIGATOR(S): Greg Caporaso, Ph.D.,
Joanne Weidhaas, M.D., Ph.D.  
CITY OF HOPE NATIONAL MEDICAL CENTER
1500 E. DUARTE ROAD
DUARTE, CA 91010 DEPARTMENT OF MEDICAL ONCOLOGY AND THERAPEUTICS RESEARCH
TITLE: COMBINING PEMBROLIZUMAB AND PALLIATIVE RADIOTHERAPY IN
GASTROESOPHAGEAL CANCER TO ENHANCE ANTI-TUMOR T CELL RESPONSE AND AUGMENT THE ABSCOPAL EFFECT  
| CITY OF HOPE PROTOCOL NUMBER:                                                                                                                                                                                                                                                                                                                                                                  | 16099                                                                                                           | VERSION:    | 04   |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------|-------------|------|
| COH Initial Submission:                                                                                                                                                                                                                                                                                                                                                                        | Protocol dated 04/08/2016                                                                                       | Version: 00 |      |
| COH Amendment 01                                                                                                                                                                                                                                                                                                                                                                               | Protocol dated 02/10/2017                                                                                       | Version: 01 |      |
| COH Amendment 02                                                                                                                                                                                                                                                                                                                                                                               | Protocol dated 07/26/2017                                                                                       | Version: 02 |      |
| COH Amendment 03                                                                                                                                                                                                                                                                                                                                                                               | Title Page dated 02/27/2018                                                                                     | Version: 03 |      |
| COH Amendment 04                                                                                                                                                                                                                                                                                                                                                                               | Protocol dated 10/16/2019                                                                                       | Version: 04 |      |
| SPONSOR/IND NUMBER: 131134 DISEASE SITE: Esophageal, gastric, and gastroesophageal cancers  STAGE (if applicable): IV  MODALITY: Intravenous PHASE/TYPE: Phase II/Prospective biomarker analysis  PRINCIPAL INVESTIGATOR: Joseph Chao, M.D.  City of Hope COLLABORATING INVESTIGATOR(S) Peter Lee, M.D.  Yi-Jen Chen, MD., Ph.D.  City of Hope  PARTICIPATING CLINICIANS: Vincent Chung, M.D., | Marwan                                                                                                          |             |      |
| Fakih, M.D., Daneng Li, M.D., Dean  Lim, M.D., City of Hope                                                                                                                                                                                                                                                                                                                                    |                                                                                                                 |             |      |
| STUDY STATISTICIAN:                                                                                                                                                                                                                                                                                                                                                                            | Paul Frankel, Ph.D.  Department of Information Sciences                                                         |             |      |
| PARTICIPATING SITES:                                                                                                                                                                                                                                                                                                                                                                           | City of Hope - Duarte  Greg Caporaso, Ph.D. Northern Arizona University/TGen  Joanne Weidhaas, M.D., Ph.D. UCLA |             |      |
| STUDY SPONSOR AND MONITOR:                                                                                                                                                                                                                                                                                                                                                                     | City of Hope                                                                                                    |             |      |
| EXTERNAL COLLABORATING  INVESTIGATORS:                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                 |             |      |  
| TABLE OF CONTENTS                                                                                                 |                                                                                                                                                             |                                                                                                            |
|-------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------|
| TRIAL SUMMARY                                                                                                     |                                                                                                                                                             |                                                                                                            |
| 1.0                                                                                                               |                                                                                                                                                             |                                                                                                            |
| 2.0                                                                                                               | TRIAL DESIGN                                                                                                                                                |                                                                                                            |
| 2.1                                                                                                               | T Trial Design .                                                                                                                                            |                                                                                                            |
| 2.2                                                                                                               | Trial Diagram.                                                                                                                                              |                                                                                                            |
| 3.0                                                                                                               | OBJECTIVE(S) & HYPOTHESIS(ES)                                                                                                                               |                                                                                                            |
| 3.1                                                                                                               | Primary Objective(s) & Hypothesis(es) .......................................................................... 7                                          |                                                                                                            |
| 3.2                                                                                                               | Secondary Objective(s) & Hypothesis(es)                                                                                                                     |                                                                                                            |
| 3.3                                                                                                               | Exploratory Objective ................................................................................................................... 7                 |                                                                                                            |
| 4.0                                                                                                               | BACKGROUND & RATIONALE                                                                                                                                      |                                                                                                            |
| Background .                                                                                                      |                                                                                                                                                             |                                                                                                            |
| 4.1                                                                                                               | 4.1.1                                                                                                                                                       | Pharmaceutical and Therapeutic Background .............................................................. 8 |
| 4.1.2                                                                                                             | Preclinical and Clinical Trial Data                                                                                                                         |                                                                                                            |
| 4.2                                                                                                               | Rationale ............................................................................................................................................... 9 |                                                                                                            |
| 4.2.1                                                                                                             | Rationale for the Trial and Selected Subject Population ........................................... 9                                                       |                                                                                                            |
| 4.2.2                                                                                                             | Rationale for Dose Selection/Regimen/Modification .............................................. 10                                                         |                                                                                                            |
| 4.2.3                                                                                                             | Rationale for Endpoints                                                                                                                                     |                                                                                                            |
| 5.0                                                                                                               | METHODOLOGY                                                                                                                                                 |                                                                                                            |
| 5.1                                                                                                               | Entry Criteria .                                                                                                                                            |                                                                                                            |
| 5.1.1                                                                                                             | Inclusion Criteria .                                                                                                                                        |                                                                                                            |
| 5.1.2                                                                                                             | Exclusion Criteria .                                                                                                                                        |                                                                                                            |
| 5.2                                                                                                               | Trial Treatments .                                                                                                                                          |                                                                                                            |
| Table 1 Trial Treatment                                                                                           |                                                                                                                                                             |                                                                                                            |
| 5.2.1                                                                                                             | Dose Selection/Modification ......................................................................................................... 19                    |                                                                                                            |
| Table 2: Dose Modification Guidelines for Drug-Related Adverse Event .................. 20                        |                                                                                                                                                             |                                                                                                            |
| 5.2.2                                                                                                             | Timing of Dose Administration                                                                                                                               |                                                                                                            |
| 5.2.3                                                                                                             | External Beam Radiotherapy .                                                                                                                                |                                                                                                            |
| 5.3                                                                                                               | Concomitant Medications/Vaccinations (allowed & prohibited) ..................... 23                                                                        |                                                                                                            |
| 5.3.1                                                                                                             | Acceptable Concomitant Medications .                                                                                                                        |                                                                                                            |
| 5.3.2                                                                                                             | Prohibited Concomitant Medications                                                                                                                          |                                                                                                            |
| 5.4                                                                                                               | Rescue Medications & Supportive Care .................................................................................. 24                                  |                                                                                                            |
| 5.4.1                                                                                                             | Supportive Care Guidelines .                                                                                                                                |                                                                                                            |
| Table 3 Infusion Reaction Treatment Guidelines .                                                                  |                                                                                                                                                             |                                                                                                            |
| 5.5                                                                                                               | Diet/Activity/Other Considerations                                                                                                                          |                                                                                                            |
| 5.5.1                                                                                                             | Diet                                                                                                                                                        |                                                                                                            |
| 5.5.2                                                                                                             | Contraception                                                                                                                                               |                                                                                                            |
| 5.5.3                                                                                                             | Use in Pregnancy .                                                                                                                                          |                                                                                                            |
| 5.5.4                                                                                                             | Use in Nursing Women .                                                                                                                                      |                                                                                                            |
| Subject Withdrawal/Discontinuation Criteria .................................................................. 28 |                                                                                                                                                             |                                                                                                            |
| 5.6                                                                                                               |                                                                                                                                                             |                                                                                                            |
| 5.6.1                                                                                                             | Discontinuation of Study Therapy after CR .................................................................... 30                                           |                                                                                                            |
| 5.7                                                                                                               | Clinical Criteria for Early Trial Termination .......................................................... 30                                                 |                                                                                                            |
| STUDY CALENDAR .                                                                                                  |                                                                                                                                                             |                                                                                                            |
| 6.0                                                                                                               |                                                                                                                                                             |                                                                                                            |
| 6.1                                                                                                               | Initial Treatment Phase                                                                                                                                     |                                                                                                            |
| 6.2                                                                                                               | Second Course Phase                                                                                                                                         |                                                                                                            |
| IRB Protocol No. 16099                                                                                            | Version Date:  10/16/2019                                                                                                                                   |                                                                                                            |  
| 7.0                                                                                     | TRIAL PROCEDURES .                                                                                           |
|-----------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------|
| 7.1                                                                                     | Trial Procedures .                                                                                           |
| 7.1.1                                                                                   | Administrative Procedures                                                                                    |
| Clinical Procedures/Assessments                                                         |                                                                                                              |
| 7.1.2                                                                                   |                                                                                                              |
| Table 4  Imaging and Treatment after 1 st radiologic evidence of progressive disease    |                                                                                                              |
| (PD) .                                                                                  |                                                                                                              |
| Laboratory Procedures/Assessments                                                       |                                                                                                              |
| 7.1.3                                                                                   |                                                                                                              |
| Table 5  Laboratory Tests                                                               |                                                                                                              |
| 7.1.4                                                                                   | O OTHER Procedures                                                                                           |
| Visit Requirements                                                                      |                                                                                                              |
| 7.1.5                                                                                   |                                                                                                              |
| DATA AND SAFETY MONITORING PLAN                                                         |                                                                                                              |
| 8.0                                                                                     |                                                                                                              |
| 8.1                                                                                     | Definition of Risk Level .                                                                                   |
| 8.2                                                                                     | Monitoring and Personnel Responsible for Monitoring ........................................... 50           |
| 8.3                                                                                     | Adverse Events and Serious Adverse Events                                                                    |
| 8.4                                                                                     | Deviations and Unanticipated Problems                                                                        |
| 8.5                                                                                     | Definition of an Overdose for This Protocol and Reporting of Overdose to                                     |
| Merck                                                                                   |                                                                                                              |
| 8.6                                                                                     | Reporting of Pregnancy and Lactation to Merck ........................................................... 54 |
| 8.7                                                                                     | Reporting of Adverse Events to Merck                                                                         |
| STATISTICAL ANALYSIS PLAN                                                               |                                                                                                              |
| 9.0                                                                                     |                                                                                                              |
| 9.1                                                                                     | Primary Objective                                                                                            |
| 9.2                                                                                     | Secondary Objectives .                                                                                       |
| 10.0                                                                                    | LABELING, PACKAGING, STORAGE AND RETURN OF CLINICAL                                                          |
| SUPPLIES .                                                                              |                                                                                                              |
| 10.1                                                                                    | Investigational Product                                                                                      |
| Table 7  Product Descriptions                                                           |                                                                                                              |
| 10.2                                                                                    | Packaging and Labeling Information .                                                                         |
| 10.3                                                                                    | Clinical Supplies Disclosure .                                                                               |
| Storage and Handling Requirements                                                       |                                                                                                              |
| 10.4                                                                                    |                                                                                                              |
| 10.5                                                                                    | Returns and Reconciliation .                                                                                 |
| 1.0                                                                                     | DATA REPORTING .                                                                                             |
| 11.1                                                                                    | DATA Reporting                                                                                               |
| 1.1.1 Confidentiality and Storage of Records .                                          |                                                                                                              |
| 1.1.2 Subject Consent Form                                                              |                                                                                                              |
| 1.1.3  Data Collection Forms and Submission Schedule .                                  |                                                                                                              |
| HUMAN SUBJECT ISSUES .                                                                  |                                                                                                              |
| 12.0                                                                                    |                                                                                                              |
| 12.1                                                                                    | Institutional Review Board .                                                                                 |
| 12.2                                                                                    | Recruitment of Subjects                                                                                      |
| 12.3                                                                                    | Study location and Performance Sites .                                                                       |
| 12.4                                                                                    | Confidentiality                                                                                              |
| 12.5                                                                                    | Financial Obligations and Compensation                                                                       |
| Informed Consent Processes .                                                            |                                                                                                              |
| 12.6                                                                                    |                                                                                                              |
| REFERENCES                                                                              |                                                                                                              |
| APPENDIX 1: ECOG Perfomance Status                                                      |                                                                                                              |
| APPENDIX 2: Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 .............. 65 |                                                                                                              |
| IRB Protocol No. 16099                                                                  | Version Date:  10/16/2019                                                                                    |  
Version: 04
appendix 3 events of clinical
city of hope protocol number

| Abbreviated Title           | Pembrolizumab and palliative radiotherapy in metastatic gastroesophageal  cancer                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
|-----------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Trial Phase                 | II                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Clinical Indication         | SCC and/or adenocarcinoma of the esophagus, GEJ, and stomach                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Trial Type                  | Prospective; Biomarker analysis                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| Route of administration     | Intravenous                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Trial Blinding              | None                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Treatment Groups            | All patients will be assigned to the same therapy of palliative radiotherapy  of 30 Gy over 10 fractions for symptoms from their primary tumor or a  single target metastatic site in combination with pembrolizumab at a fixed  dose of 200 mg every 3 weeks.                                                                                                                                                                                                                                                                                                                                                                     |
| Number of trial subjects    | 14                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
| Estimated enrollment period | 24 months                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| Estimated duration of trial | 36 months from the first patient signing informed consent until the last  patient's last visit.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| Duration of Participation   | Patients will complete radiation therapy of 30 Gy in 10 fractions and will  continue pembrolizumab until confirmed disease progression, or  intolerable toxicity, or an initial 35 administrations (approximately 2  years). Patients who stop pembrolizumab with stable disease or better or  35 administrations of therapy without progression may be eligible at the  discretion of the investigator to receive up to an additional year of  pembrolizumab therapy. Patients with evidence of progressive disease  (PD) on imaging and are clinically stable may continue to be treated at the  discretion of the investigator. |
appendix 3 events of clinical
1.0 trial summary 2.0 trial

This is a single-arm, prospective, phase II, biomarker analysis trial of pembrolizumab in combination with palliative radiotherapy for patients with metastatic squamous cell or adenocarcinoma of the esophagus, stomach, or gastroesophageal junction (GEJ). We will enroll 14 patients within our institution who are in need of palliative radiation for symptoms related to their primary tumor including pain, dysphagia, and bleeding. Patients with a single metastatic site in need of palliative radiation (e.g., pain from a bony metastasis, enlarged lymph nodes, liver metastasis, etc.) will also be eligible provided they have other measurable metastatic sites outside of the radiation field. The exception will be patients who require palliative radiation to a symptomatic central nervous system (CNS) metastasis. The first dose of palliative radiation and first dose of pembrolizumab will commence on cycle 1, day 1. Participation in this trial will be dependent on patients having a metastatic site amenable to ultrasound and/or CT-guided biopsy, inclusive of patients with malignant ascites amenable to ultrasound-guided aspiration, and agreeing to provide pre- and post-treatment biopsies for the Version: 04 biomarker analysis primary endpoint of the study. Patients who are undergoing palliative radiation for a single target metastatic site, and only the primary tumor is amenable to biopsy are also eligible to participate if they consent to endoscopic pre- and post-treatment biopsies. Treatment will continue until documented clinical PD, unacceptable AE(s), intercurrent illness that prevents further administration of treatment, investigator's decision to withdraw the patient, patient withdraws consent, pregnancy of the subject, noncompliance with trial treatment or procedure requirements, completion of 35 administrations (approximately 2 years) of treatment with study medication or achievement of a complete response. 2.2 Trial Diagram
appendix 3 events of clinical
study schema

Pembrolizumab 200 mg every 3 weeks CT every 6 weeks for 18 weeks then every 9 weeks for RECIST1.1 assessment Blood sampling for PBMC coll
appendix 3 events of clinical
3.0 objective(s) & hypothesis(es) 3.1

(1) **Objective:** To establish that the combination of pembrolizumab and traditional external beam multifractionated RT to the primary tumor or a single target metastatic site of patients with metastatic gastric, esophageal, and/or GEJ cancers will lead to an increase in tumor infiltrating cytotoxic T-cells and circulating cytotoxic T cells and a reduction in immunosuppressive Tregs and MDSCs in metastatic sites. Hypothesis: The combination of pembrolizumab and traditional external beam multifractionated RT to the primary tumor or a single target metastatic site will lead to increased immune-mediated tumor cytoxicity via a demonstrable increase in tumor infiltrating and circulating cytotoxic T cells and a reduction in immunosuppressive Tregs and MDSCs within metastatic sites post-therapy.
appendix 3 events of clinical
3.2 secondary objective(s) & hypothesis(es)

(1) **Objective**: To establish that the combination of pembrolizumab and RT is feasible in this patient population and evaluate toxicities per NCI CTCAE ver.4.03.  
Hypothesis: The combination of pembrolizumab and RT will be feasible with an acceptable safety profile to warrant future studies.  
(2) **Objective**: To evaluate overall response rate (ORR) per RECIST1.1 and irRECIST in this treatment population and correlate with tumor T-cell response. Hypothesis: The combination of pembrolizumab and RT will demonstrate clinical efficacy with a promising response rate compared to historical controls to warrant future studies.  
(3) **Objective**: To evaluate progression-free (PFS) and overall survival (OS) in this treatment population. Hypothesis: The combination of pembrolizumab and RT will demonstrate promising PFS and OS to warrant future studies.
appendix 3 events of clinical
3.3 exploratory objectives

(1) **Objective:** To measure changes in whole genome serum miRNA signatures before and after protocol therapy and correlate with tumor/immune/stromal cell miRNA expression profiling determined by deep sequencing.  
(2) **Objective:** To measure changes in fecal and oral microbiomic diversity and correlate with ORR, PFS, and OS.  
(3) **Objective:** To assess germline mutations in a panel of miRNA regulatory genes using the MiraDx assay as predictors of response and toxicity to pembrolizumab and RT. Version: 04
4.0 background & rationale
4.1 background

Refer to the Investigator's Brochure (IB)/approved labeling for detailed background information on pembrolizumab (aka MK-3475).
4.0 background & rationale
4.1.1 pharmaceutical and therapeutic background

The importance of intact immune surveillance in controlling outgrowth of neoplastic transformation has been known for decades. Accumulating evidence shows a correlation between tumor-infiltrating lymphocytes (TILs) in cancer tissue and favorable prognosis in various malignancies. In particular, the presence of CD8+ T-cells and the ratio of CD8+ effector T-cells / FoxP3+ regulatory T-cells seems to correlate with improved prognosis and long-term survival in many solid tumors. The PD-1 receptor-ligand interaction is a major pathway hijacked by tumors to suppress immune control. The normal function of PD-1, expressed on the cell surface of activated Tcells 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 has been shown to negatively regulate antigen receptor signaling upon engagement of its ligands (PD-L1 and/or PD-L2). The structure of murine PD-1 has been resolved. PD-1 and family members are type I transmembrane glycoproteins containing an Ig Variable-type (V-type) domain responsible for ligand binding and a cytoplasmic tail which is responsible for the binding of signaling molecules. The cytoplasmic tail of PD-1 contains 2 tyrosine-based signaling motifs, an immunoreceptor tyrosine-based inhibition motif (ITIM) and an immunoreceptor tyrosine-based switch motif (ITSM). Following T-cell stimulation, PD-1 recruits the tyrosine phosphatases SHP-1 and SHP-2 to the ITSM motif within its cytoplasmic tail, leading to the dephosphorylation of effector molecules such as CD3ζ, PKCθ and ZAP70 which are involved in the CD3 T-cell signaling cascade. The mechanism by which PD-1 down modulates T-cell responses is similar to, but distinct from that of CTLA-4 as both molecules regulate an overlapping set of signaling proteins. PD-1 was shown to be expressed on activated lymphocytes including peripheral CD4+ and CD8+ T-cells, B-cells, T regs and Natural Killer cells. Expression has also been shown during thymic development on CD4-CD8- (double negative) T-cells as well as subsets of macrophages and dendritic cells. The ligands for PD-1 (PD-L1 and PD-L2) are constitutively expressed or can be induced in a variety of cell types, including nonhematopoietic tissues as well as in various tumors . Both ligands are type I transmembrane receptors containing both IgV- and IgC-like domains in the extracellular region and contain short cytoplasmic regions with no known signaling motifs. Binding of either PD-1 ligand to PD-1 inhibits T-cell activation triggered through the T-cell receptor. PD-L1 is expressed at low levels on various non-hematopoietic tissues, most notably on vascular endothelium, whereas PD-L2 protein is only detectably expressed on antigen-presenting cells found in lymphoid tissue or chronic inflammatory environments. PD-L2 is thought to control immune T-cell activation in lymphoid organs, whereas PD-L1 serves to dampen unwarranted T-cell function in peripheral tissues. Although healthy organs express little (if any) PD-L1, a variety Version: 04 of cancers were demonstrated to express abundant levels of this T-cell inhibitor. PD-1 has been suggested to regulate tumor-specific T-cell expansion in subjects with melanoma (MEL). This suggests that the PD-1/PD-L1 pathway plays a critical role in tumor immune evasion and should be considered as an attractive target for therapeutic intervention. Pembrolizumab is a potent and highly selective humanized monoclonal antibody (mAb) of the IgG4/kappa isotype designed to directly block the interaction between PD-1 and its ligands, PD-L1 and PD-L2. KeytrudaTM (pembrolizumab) has recently been approved in the United Stated for the treatment of patients with unresectable or metastatic melanoma and disease progression following ipilumumab and, if BRAF V600 mutation positive, a BRAF inhibitor.
4.0 background & rationale
4.2 rationale 4.2.1 rationale for

Metastatic squamous cell carcinomas (SCC) and adenocarcinomas of the esophagus, stomach, and gastroesophageal junction (GEJ) account for a high proportion of worldwide cancerrelated mortality. While some progress has been made for HER2 and VEGFR2 targeted therapies in adenocarcinomas,1,2 options for metastatic SCC remain dismal. Evidence for cytotoxic agents in SCC typically stem from a small proportion of patients enrolled in large phase III trials predominated by patients with adenocarcinoma histologies.3 Novel targeted therapeutic approaches for both subtypes are desperately needed. Pembrolizumab has demonstrated encouraging preliminary evidence of activity in small cohorts of gastric and esophageal cancer patients within the KEYNOTE-012 and KEYNOTE028 trials, respectively.4,5 Both trials selected for patients with evidence of PD-L1 expression within tumor stroma and/or tumor cells. KEYNOTE-012 reported a 22.2% overall response rate by central review, while KEYNOTE-028 noted a 30.4% overall response rate when assessed by investigator review. The activity of pembrolizumab in gastroesophageal cancer patients without tumor PD-L1 expression remains unknown, though lack of PD-L1 expression does not necessarily translate to an absolute lack of response to immune checkpoint inhibitors in pooled analyses of patients with melanoma, NSCLC, and genitourinary malignancies.6 Given the promising early evidence of clinical efficacy in gastroesophageal cancers, strategies should be further developed to enhance the potency of immune checkpoint inhibitors, even in patients whose tumors are currently not considered to have detectable PD-L1 expression. The abscopal effect is a rarely observed though well annotated clinical phenomenon in cancer radiotherapy (RT), in which non-irradiated metastatic lesions distant from the primary tumor site directly subjected to radiation are noted to regress. This phenomenon has been attributed to immune-mediated effects in preclinical models,7 and provides rationale that immune checkpoint inhibition and RT could act synergistically. In a recent preclinical study, PD-1 was reported to suppress RT antitumor response, though delivery of a PD-1 blocking antibody Version: 04 enhanced antitumor response at the primary radiated site as well as non-irradiated metastatic lesions.8 Furthermore, radiation therapy has been shown to drive up the expression of PD-L1 tumor expression in preclinical models.8,9,10 Mounting evidence also supports that mutational load in tumors correlate with clinical benefit from immune checkpoint inhibition.11 Results from The Cancer Genome Atlas (TCGA) have demonstrated both esophageal SCC and gastric adenocarcinomas demonstrate a high rate of somatic mutations.12,13 Furthermore, the development of esophageal SCC is commonly attributed to tobacco smoking, a risk factor shared with NSCLC in which anti-PD-1 strategies have been successful. It is not uncommon for patients with metastatic disease to undergo palliative, traditional external beam multifractionated RT to their primary tumor for the treatment of dysphagia, pain, or gastrointestinal bleeding or a single metastatic site such as a bone metastasis for the treatment of pain. The concordant delivery of pembrolizumab during palliative RT thus serves as an attractive window-of-opportunity trial to determine if the abscopal effect may be augmented with immune checkpoint blockade. We propose a prospective trial to assess pre- and post-treatment biopsies of patients' metastatic sites with the hypothesis that tumor cytotoxic T cells will be increased with combining pembrolizumab and palliative RT with corresponding improvement in clinical activity. As we will only be radiating a single target lesion in this study population, assessment of response among non-irradiated metastatic sites will serve as a true measure of the abscopal effect. Toxicities are not anticipated to be overlapping for these two modalities, though safety should still be assessed in this early cohort of patients to ensure immune-mediated or radiationinduced toxicities are not exacerbated by the combination. At City of Hope where patients will be solely recruited for this trial, we have extensive experience in the conduct of pre- and post-treatment biopsy studies having completed accrual to a pilot trial of the novel nanopharmaceutical CRLX101 in this disease subset (Clinicaltrials.gov, NCT01612546). We also have a broad gastroesophageal cancer patient population evaluating more than 60 new cases per year due to our institution serving the diverse, multicultural population of the San Gabriel Valley in Los Angeles County. Dr. Peter Lee, MD, Chair of the Department of Immuno-Oncology, will serve as a collaborating investigator on this study given his laboratory's expertise in translational analyses of tumor/immune/stromal cell interactions.
4.0 background & rationale
4.2.2 rationale for dose selection/regimen/modification

An open-label Phase I trial (Protocol 001) is being conducted to evaluate the safety and clinical activity of single agent MK-3475. The dose escalation portion of this trial evaluated three dose levels, 1 mg/kg, 3 mg/kg, and 10 mg/kg, administered every 2 weeks (Q2W) in subjects with advanced solid tumors. All three dose levels were well tolerated and no dose-limiting toxicities were observed. This first in human study of MK-3475 showed evidence of target engagement and objective evidence of tumor size reduction at all dose levels (1 mg/kg, 3 mg/kg and 10 mg/kg Q2W). No MTD has been identified to date. 10.0 mg/kg Q2W, the highest dose tested in PN001, will be the dose and schedule utilized in Cohorts A, B, C and D of this protocol to test for initial tumor activity. Recent data from other clinical studies within the MK-3475 program has shown that a lower dose of MK-3475 and a less frequent schedule may be sufficient for target engagement and clinical activity. Version: 04 PK data analysis of MK-3475 administered Q2W and Q3W showed slow systemic clearance, limited volume of distribution, and a long half-life (refer to IB). Pharmacodynamic data (IL2 release assay) suggested that peripheral target engagement is durable (>21 days). This early PK and pharmacodynamic data provides scientific rationale for testing a Q2W and Q3W dosing schedule. A population pharmacokinetic analysis has been performed using serum concentration time data from 476 patients. Within the resulting population PK model, clearance and volume parameters of MK-3475 were found to be dependent on body weight. The relationship between clearance and body weight, with an allometric exponent of 0.59, is within the range observed for other antibodies and would support both body weight normalized dosing or a fixed dose across all body weights. MK-3475 has been found to have a wide therapeutic range based on the melanoma indication. The differences in exposure for a 200 mg fixed dose regimen relative to a 2 mg/kg Q3W body weight based regimen are anticipated to remain well within the established exposure margins of 0.5 - 5.0 for MK-3475 in the melanoma indication. The exposure margins are based on the notion of similar efficacy and safety in melanoma at 10 mg/kg Q3W vs. the proposed dose regimen of 2 mg/kg Q3W (i.e. 5-fold higher dose and exposure). The population PK evaluation revealed that there was no significant impact of tumor burden on exposure. In addition, exposure was similar between the NSCLC and melanoma indications. Therefore, there are no anticipated changes in exposure between different indication settings. The rationale for further exploration of 2 mg/kg and comparable doses of pembrolizumab in solid tumors is based on: 1) similar efficacy and safety of pembrolizumab when dosed at either 2 mg/kg or 10 mg/kg Q3W in melanoma patients, 2) the flat exposure-response relationships of pembrolizumab for both efficacy and safety in the dose ranges of 2 mg/kg Q3W to 10 mg/kg Q3W, 3) the lack of effect of tumor burden or indication on distribution behavior of pembrolizumab (as assessed by the population PK model) and 4) the assumption that the dynamics of pembrolizumab target engagement will not vary meaningfully with tumor type. The choice of the 200 mg Q3W as an appropriate dose for the switch to fixed dosing is based on simulations performed using the population PK model of pembrolizumab showing that the fixed dose of 200 mg every 3 weeks will provide exposures that 1) are optimally consistent with those obtained with the 2 mg/kg dose every 3 weeks, 2) will maintain individual patient exposures in the exposure range established in melanoma as associated with maximal efficacy response and 3) will maintain individual patients exposure in the exposure range established in melanoma that are well tolerated and safe. A fixed dose regimen will simplify the dosing regimen to be more convenient for physicians and to reduce potential for dosing errors. A fixed dosing scheme will also reduce complexity in the logistical chain at treatment facilities and reduce wastage.
4.0 background & rationale
4.2.3 rationale for endpoints 4.2.3.1

The clinical efficacy of combining pembrolizumab and palliative radiotherapy will be measured by assessing overall response rate by RECIST 1.1 and irRECIST. To truly measure the abscopal effect, patients will be required to have metastatic disease sites outside the field of palliative radiation that are considered measurable by RECIST 1.1.
4.0 background & rationale
4.2.3.2 biomarker research analysis of

Radiology-guided biopsies will utilize 20-gauge core biopsy needles. Biopsies obtained via an endoscopic approach will utilize standard endoscopic biopsy forceps in which specimens are typically 3-6 mm in diameter. As such tissue samples will be composed of both tumor cells and associated tumor stroma. Fresh tumor samples will be immediately delivered to the laboratory of Dr. Peter Lee for both ex vivo tumor/immune/stromal cell culture and expansion as well as histologic analyses. Patients with fresh malignant ascites collected will also be immediately delivered to the lab for ex vivo tumor/immune/stromal cell culture and expansion alone. Dr. Lee's lab will utilize quantitative spatial image analysis to examine changes in tumor cell-stromal interactions including CD4, CD8, Treg, and MDSC populations pre- and post-therapy. PD-L1 expression within the tumor, on cancer cells and stromal cells, will be analyzed by immunohistochemistry (IHC). PD-1 expression on tumor infiltrating T cells and circulating peripheral blood mononuclear cell (PBMC) T cells will be analyzed by a combination of IHC and flow cytometry. Immune cell populations will be further analyzed via high dimensional flow cytometry to measure levels of Tregs and MDSCs, which will allow us to calculate the ratio of effector T cells to Tregs and MDSCs, respectively. Ex vivo isolated T cells will also be analyzed for proliferative capacity (CFSE dilution) and cytokine production (IFN-γ and IL-17) after stimulation with anti-CD3 and/or PMA and Ionomycin. Furthermore, by use of multi-color IHC we will determine influences of pembrolizumab+RT treatment on the magnitude and proximity of CD8 T cells to cancer cells within the tumor. Lastly, we will analyze changes in the diversity of T cell repertoire in both PD-1 positive and PD-1 negative T cell populations following pembrolizumab+RT treatment via deep sequencing of the TCR Vβ CDR3 region. Such changes in T cell repertoire can be suggestive of potential epitope spreading for anti-tumor antigens and reversal of tumor antigen-specific T cell anergy. Genomic analyses utilizing City of Hope's Integrative Genomics Core will also be performed on the corresponding cancer/stromal/immune cell populations via total RNA-seq for coding and non-coding RNAs (including miRNAs). Performance of these studies will require several highly developed techniques that have been routinely conducted in Dr. Peter Lee's lab. A prototype BD microfluidic FACS instrument allows for 12-color analysis of low cell numbers, thereby allowing maximal data acquisition out of small sample sizes. A powerful quantitative, spatial image analysis system will enable Version: 04 us to analyze immune and cancer cells in tissues via 8-color histology. Lastly, Dr. Lee's lab has considerable expertise in TCR repertoire analysis via deep sequencing, which can yield information on T cell specificity to unknown antigens.
4.0 background & rationale
serum circulating mirna sequencing

10 mL of whole blood will be collected from each patient at prespecified time points and serum separated per standard procedures. Total RNA will be extracted using Trizol and sent to the Integrative Genomics Core at City of Hope for miRNA-seq. The Integrative Genomics Core is a shared resource at City of Hope and is equipped with all major state-of-the-art microarray and sequencing platforms for genomic studies, including Illumina's Hiseq 2500 and Life Technology's Ion Proton sequencers, Illumina's Hiscan Beadchip system, Affymetrix's GeneChip system, and Agilent's microarray system. With a highly experienced team of bioinformaticians integrated within the core, efficient genomic data analysis services will be provided to convert high throughput data into biologically interpretable results. They have extensive expertise in utilizing both commercial and open-source software tools for sequencing data analysis including but not limited to R/Bioconductor, IGV, Bowtie, TopHat, Cufflinks, Novoalign, MACS, MEME, Transfac, BWA, GATK, Samtools, Gene Set Enrichment Analysis (GSEA), Ingenuity Pathway Analysis and DAVID. Sequence reads that match human miRNAs in Sanger mirBase will be calculated and analyzed. Circulating whole genome miRNA signatures will be compared to miRNAs sequenced from total RNA-seq from the corresponding tumor biopsy timepoints to aid in biomarker discovery of serum miRNAs that may predict for immunotherapy response or resistance. miR-23a will be of particular interest given its description as a gastric cancer oncomir and function as a repressor of T cell cytotoxicity in preclinical miRNA screens.14,15 miR-34a and miR-200 will be other miRNAs of interest to measure given reporting of their ability to suppress PD-L1 expression in other experimental systems.16,17
4.0 background & rationale
5.0 methodology 5.1 entry criteria

Diagnostic or laboratory studies performed exclusively to determine eligibility for this trial will be done only after obtaining written informed consent. Studies or procedures that were for clinical indications (not exclusively to determine study eligibility) may be used for baseline values and/or to determine pre-eligibility, even if the studies were done before informed consent was obtained. The informed consent process is to be fully documented, and the prospective participant must receive a copy of the signed informed consent document. All screening procedures and their respective windows are detailed in the Study Activity Calendar.
4.0 background & rationale
participant enrollment coh dcc availability

Eligible subjects will be registered on the study centrally by the Data Coordinating Center (DCC) at City of Hope. DCC staff are available between the hours of 8.00 am and 5.00 pm PST, Monday through Friday (except holidays). DCC contact information is as follows:
o Phone: (626) 256-4673 ext. 83968 o E-mail: DCC@coh.org Eligible subjects must be registered **prior** to start of protocol therapy. Issues that would cause treatment delays should be discussed with the Principal Investigator. If a subject does not receive protocol therapy following registration, the subject's registration on the study may be canceled after discussion with the PI. The Data Coordinating Center should be notified of cancellations as soon as possible.
4.0 background & rationale
registration process

To register a participant the subsequent procedure is to be followed:
1. The study team should contact the DCC via telephone or email to provide notification regarding the pending registration and communicate desired timeline of the registration, especially if it must be completed promptly to meet the registration window.  
2. The protocol nurse or CRC will email a copy of the following documents to the DCC:
o Completed eligibility checklist (printed from Section 5.1 of the protocol)
o Signed Informed Consent o Signed subject's bill of Rights o Signed HIPAA authorization form and o Provide copies of source documentation only if not readily available as a finalized record in the COH Electronic Medical Record (EMR).  
3. After having received all transferred documentation, the DCC will complete the review the documents to verify eligibility, working with the study team as needed to resolve any missing required source elements. A participant failing to meet all protocol eligibility requirements will not be registered.  
4. Once eligibility has been confirmed, DCC staff will register the participant by:
assigning a subject accession number, register the subject on study centrally into a COH clinical trials management system (e.g. MIDAS), and enter the subject into the eCRF system, Medidata RAVE.  
5. Once registration has been completed, DCC staff will send a Confirmation of Registration Form within 24 hours, including the participant study number to:
o The site study team: Principal Investigator, treating physician, protocol statistician, protocol nurse, CRC and COH IDS Pharmacy.  
o the COH sponsor team designees
4.0 background & rationale
screen failures and registered participants

The DCC is to be notified of all participants who sign consent but do not meet eligibility criteria or do not initiate protocol therapy.
4.0 background & rationale
5.1.1 inclusion criteria

Participants must meet all of the following criteria on screening examination to be eligible to participate in the study:  
Patient MRN: Patient Initials: (F,M,L):  
Informed Consent and Willingness to Participate
___ 1. Documented informed consent of the participant ___ 2. Willing to provide tumor tissue amenable to ultrasound or CT-guided biopsy for biomarker analyses.  
Patients with malignant ascites are permitted to participate and provide ascites samples for biomarker analyses.  
Patients receiving radiation to a single metastatic site in which only the primary tumor is accessible for biopsy by endoscopy will also be eligible.  
Age Criteria, Performance Status and Life Expectancy
___ 3. Age: t 18 years  
___ 4. ECOG performance status of ≤ 1 ___ 5. Life expectancy of ≥ 3 months
4.0 background & rationale
nature of illness and treatment

___ 6. Diagnosis of metastatic squamous cell carcinoma and/or adenocarcinoma of the esophagus, gastroesophageal junction, or stomach in need of palliative radiotherapy to the primary tumor or a single metastatic site for symptoms such as pain, dysphagia, and/or gastrointestinal bleeding.  
Patients with adenocarcinoma histology and known HER2overexpressing disease are permitted to participate if they progressed or are intolerant of prior trastuzumab-containing therapy.  
___ 8. Have no limits on prior lines of therapy or may be treatment-naïve if in need of palliative RT provided the patient has not received prior anti-PD-1, anti-PD-L1, or anti-PD-L2 therapy.
Laboratory Criteria (within 10 days of treatment initiation unless indicated otherwise)  
Version: 04  
___ 7. Measurable metastatic sites of disease outside of the target lesion  
undergoing palliative radiation based on RECIST 1.1 as assessed by the investigator.  
| ___ 9.                                                                                                                                                            | ANC ≥ 1,500/mm3                                                                                                                                   | ANC:         | Date:   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------|--------------|---------|
| ___ 10.                                                                                                                                                           | Platelets ≥ 100,000/mm3                                                                                                                           | Plts:        | Date:   |
| ___ 11.                                                                                                                                                           | Hemoglobin ≥ 9 g/dL                                                                                                                               | Hgb:         | Date:   |
| ƒ                                                                                                                                                                   | May receive transfusion to meet this goal as it is anticipated a subset of  patient will require palliative radiation to a bleeding primary tumor |              |         |
| ___ 12.                                                                                                                                                           | Total serum bilirubin ≤ 1.5 x ULN                                                                                                                 |              |         |
| OR                                                                                                                                                                | Direct bilirubin ≤ ULN if total                                                                                                                   |              |         |
| bilirubin levels > 1.5 x ULN                                                                                                                                      | ULN:  Bil:                                                                                                                                        | Date:        |         |
| Direct Bil:                                                                                                                                                       |                                                                                                                                                   |              |         |
| ___ 13.                                                                                                                                                           | Albumin ≥ 2.5 mg/dL                                                                                                                               | Albumin:     | Date:   |
| ___ 14.                                                                                                                                                           | AST and ALT ≤ 2.5 x ULN OR ≤                                                                                                                      | ULN:         | Date:   |
| 5.0 x ULN if liver metastases present                                                                                                                             | ALT:  ULN:                                                                                                                                        | Date:        |         |
| AST:                                                                                                                                                              |                                                                                                                                                   |              |         |
| ___ 15.                                                                                                                                                           | Serum creatinine ≤ 1.5 x ULN OR                                                                                                                   |              |         |
| Creatinine clearancea                                                                                                                                             | ≥                                                                                                                                                 | 60 mL/min if |         |
| creatinine levels > 1.5 x ULN  ƒ GFR can also be used in place of  creatinine or CrCl                                                                                                                                                                   |                                                                                                                                                   |              |         |
| a If measured or calculated per institutional standard                                                                                                            | ULN:                                                                                                                                              | Date:        |         |
| Serum Cr: Cr Cl:                                                                                                                                                  |                                                                                                                                                   |              |         |
| ___ 16.                                                                                                                                                           | If not receiving anticoagulants:                                                                                                                  |              |         |
| International Normalized Ratio (INR)  OR Prothrombin (PT) ≤ 1.5 x ULN                                                                                             | ULN:  INR:  PT:                                                                                                                                   | Date:        |         |
| If on anticoagulant therapy: PT must  be within therapeutic range of intended  use of anticoagulants                                                              |                                                                                                                                                   |              |         |
| ___ 17.                                                                                                                                                           | If not receiving anticoagulants:                                                                                                                  |              |         |
| Activated Partial Thromboplastin Time  (aPTT) ≤ 1.5 x ULN  If on anticoagulant therapy: aPTT  must be within therapeutic range of  intended use of anticoagulants | ULN:                                                                                                                                              | Date:        |         |
| aPTT:                                                                                                                                                             |                                                                                                                                                   |              |         |  
___ 18. Negative urine or serum pregnancy  
test (female of childbearing potential  
only)  
If the urine test is positive or cannot  
be confirmed as negative, a serum pregnancy test will be required  
| Urine test:  Serum test:   |
|----------------------------|  
Contraception  
| Date:   |
|---------|  
___ 19. Female of childbearing potential: willing to use 2 methods of birth control or be surgically sterile, or abstain from heterosexual activity for the course of the study through 120 days after the last dose of study medication.  
Childbearing potential defined as not being surgically sterilized or have not been free from menses for > 1 year.  
___ 20. Male: Use an adequate method of contraception starting with the first dose of study therapy through 120 days after the last dose of study therapy.
4.0 background & rationale
5.1.2 exclusion criteria prior therapy

___ 1. Anti-PD-1, anti-PD-L1, or anti-PD-L2 agents ___ 2. Prior radiation therapy within the field of the target lesion that in the opinion of the treating radiation oncologist would preclude further palliative radiation to a dose of 30 Gy.  
___ 3. Anti-cancer monoclonal antibody (mAb) within 4 weeks prior to study Day 1 or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to agents administered more than 4 weeks earlier.  
___ 4. Chemotherapy, targeted small molecule therapy, or radiation therapy within 2 weeks prior to study Day 1 or who has not recovered (i.e., ≤ Grade 1 or at baseline) from adverse events due to a previously administered agent.  
Note: Subjects with ≤ Grade 2 neuropathy are an exception to this criterion and may qualify for the study.  
Note: If subject received major surgery, they must have recovered adequately from the toxicity and/or complications from the intervention prior to starting therapy.  
___ 5. Live vaccine within 30 days of planned start of study therapy.  
Note: Seasonal influenza vaccines for injection are generally inactivated flu vaccines and are allowed; however intranasal influenza vaccines (e.g., Flu-Mist®) are live attenuated vaccines, and are not allowed.  
___ 6. Immunosuppressive therapy within 7 days prior to the first dose of trial treatment.
4.0 background & rationale
concomitant therapy

___ 8. Currently receiving an investigational agent ___ 9. About to undergo palliative radiation for a symptomatic CNS metastasis ___ 10. Systemic steroid therapy Other Illnesses and Conditions
___ 11. Hypersensitivity to pembrolizumab or any of its excipients  
___ 12. Diagnosis of immunodeficiency ___ 13. Active autoimmune disease that has required systemic treatment in the past 2 years (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs).  
Replacement therapy (e.g. thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment.
___ 14. Known history of, or any evidence of active, non-infectious pneumonitis.  
___ 15. Current active infection requiring systemic therapy ___ 16. Known history of active TB, HIV 1/2, Hepatitis B or Hepatitis C ___ 17. Known additional malignancy that is progressing or requires active treatment.  
Exceptions include basal cell carcinoma of the skin or squamous cell carcinoma of the skin that has undergone potentially curative therapy or in situ cervical cancer.
___ 18. Known active central nervous system (CNS) metastases and/or carcinomatous meningitis.  
Subjects with previously treated brain metastases may participate provided they are stable (without evidence of progression by imaging for at least four weeks prior to the first dose of trial treatment and any neurologic symptoms have returned to baseline), have no evidence of new or enlarging brain metastases, and are not using steroids for at least 7 days prior to trial treatment. This exception does not include carcinomatous meningitis which is excluded regardless of clinical stability.  
Version: 04
___ 7. Investigational device within 4 weeks of the first dose of treatment ___ 19. History or current evidence of any condition, therapy, or laboratory abnormality that might confound the results of the trial, interfere with the subject's participation for the full duration of the trial, or is not in the best interest of the subject to participate, in the opinion of the treating investigator.
___ 21. Pregnant or breastfeeding (female only).
4.0 background & rationale
5.2 trial treatments

The treatment to be used in this trial is outlined below in Table 1.  
Version: 04  
___ 20. Known psychiatric or substance abuse disorders that would interfere  
with cooperation with the requirements of the trial.  
| Drug            | Dose/Potenc                              | Dose                                      |             |                 |             |
|-----------------|------------------------------------------|-------------------------------------------|-------------|-----------------|-------------|
| y               | Frequenc y                               | Route of                                  |             |                 |             |
| Administratio n | Regimen/Treatmen                         | Use                                       |             |                 |             |
| t Period        |                                          |                                           |             |                 |             |
| Pembrolizuma    | 200 mg                                   | Q3W                                       | IV infusion | Day 1 of each 3 | Experimenta |
| b               | week cycle                               | l                                         |             |                 |             |
| Radiotherapy    | 3 Gy                                     | Daily                                     | External    | Daily except    |             |
| Beam            | weekends and  holidays for 10  fractions | Standard of  care and  combination  agent |             |                 |             |  
Trial treatment should begin as close as possible to the date on which treatment is allocated/assigned. The first dose of pembrolizumab on cycle 1, day 1 should occur on the same day after the first fraction of radiation therapy.
4.0 background & rationale
5.2.1 dose selection/modification 5.2.1.1 dose

The rationale for selection of the dose to be used in this trial is provided in Section 4.0 - Background and Rationale.  
Details on preparation and administration of pembrolizumab (aka MK-3475) are provided in the Pharmacy Manual.
4.0 background & rationale
5.2.1.2 dose modification

Adverse events (both non-serious and serious) associated with pembrolizumab exposure may represent an immunologic etiology. These adverse events may occur shortly after the first dose or several months after the last dose of treatment. Pembrolizumab must be withheld for drugrelated toxicities and severe or life-threatening AEs as per Table 2 below. See Section 5.4.1 and Events of Clinical Interest Guidance Document for supportive care guidelines, including use of corticosteroids.  
| Table 2: Dose Modification Guidelines for Drug-Related Adverse Event  Hold                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                 |                                                                                                                                            |                                                                                                                                                                      |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Toxicity                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | Treatment                                                       | Timing for Restarting Treatment                                                                                                            | Discontinue Subject                                                                                                                                                  |
| For Grade  2-3                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Toxicity resolves to Grade 0-1.                                 | Toxicity does not resolve within 12 weeks of last dose or inability  to reduce corticosteroid to 10 mg or less of prednisone or equivalent |                                                                                                                                                                      |
| Diarrhea/Colitis                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | per day within 12 weeks.                                        |                                                                                                                                            |                                                                                                                                                                      |
| 4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | Permanently discontinue                                         | Permanently discontinue                                                                                                                    |                                                                                                                                                                      |
| 2                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | Toxicity resolves to Grade 0-1                                  | Toxicity does not resolve within 12 weeks of last dose.                                                                                    |                                                                                                                                                                      |
| AST, ALT, or                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                 |                                                                                                                                            |                                                                                                                                                                      |
| Increased Bilirubin                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 3-4                                                             | Permanently discontinue  (see exception below)1                                                                                            | Permanently discontinue                                                                                                                                              |
| Hold pembrolizumab for new onset Type 1  diabetes mellitus or Grade 3-4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | Resume pembrolizumab when patients are clinically and           |                                                                                                                                            |                                                                                                                                                                      |
| hyperglycemia associated with evidence of                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | metabolically stable.                                           |                                                                                                                                            |                                                                                                                                                                      |
| beta cell failure.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |                                                                 |                                                                                                                                            |                                                                                                                                                                      |
| Type 1 diabetes  mellitus (if new  onset) or  Hyperglycemia                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | T1DM or  3-4                                                    |                                                                                                                                            |                                                                                                                                                                      |
| Hypophysitis                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 2-3                                                             | Toxicity resolves to Grade 0-1                                                                                                             | Toxicity does not resolve within 12 weeks of last dose or inability  to reduce corticosteroid to 10 mg or less of prednisone or equivalent  per day within 12 weeks. |
| 4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | Permanently discontinue                                         | Permanently discontinue                                                                                                                    |                                                                                                                                                                      |
| Toxicity does not resolve within 12 weeks of last dose or inability                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                 |                                                                                                                                            |                                                                                                                                                                      |
| Hyperthyroidism                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 3                                                               | Toxicity resolves to Grade 0-1                                                                                                             | to reduce corticosteroid to 10 mg or less of prednisone or equivalent  per day within 12 weeks.                                                                      |
| 4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | Permanently discontinue                                         | Permanently discontinue                                                                                                                    |                                                                                                                                                                      |
| Therapy with pembrolizumab can be                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | Therapy with pembrolizumab can be continued while treatment for |                                                                                                                                            |                                                                                                                                                                      |
| Hypothyroidism                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 2-4                                                             | continued while treatment for the thyroid                                                                                                  | the thyroid disorder is instituted.                                                                                                                                  |
| disorder is instituted                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |                                                                 |                                                                                                                                            |                                                                                                                                                                      |
| Infusion Reaction                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | 3-4                                                             | Permanently discontinue                                                                                                                    | Permanently discontinue                                                                                                                                              |
| Toxicity does not resolve within 12 weeks of last dose or inability                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                 |                                                                                                                                            |                                                                                                                                                                      |
| Pneumonitis                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 2                                                               | Toxicity resolves to Grade 0-1                                                                                                             | to reduce corticosteroid to 10 mg or less of prednisone or equivalent  per day within 12 weeks.                                                                      |
| 3-4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | Permanently discontinue                                         | Permanently discontinue                                                                                                                    |                                                                                                                                                                      |
| Toxicity does not resolve within 12 weeks of last dose or inability                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                 |                                                                                                                                            |                                                                                                                                                                      |
| Renal Failure or                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 2                                                               | Toxicity resolves to Grade 0-1                                                                                                             | to reduce corticosteroid to 10 mg or less of prednisone or equivalent                                                                                                |
| Nephritis                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | per day within 12 weeks.                                        |                                                                                                                                            |                                                                                                                                                                      |
| 3-4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | Permanently discontinue                                         | Permanently discontinue                                                                                                                    |                                                                                                                                                                      |
| Toxicity does not resolve within 12 weeks of last dose or inability                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                 |                                                                                                                                            |                                                                                                                                                                      |
| All Other DrugRelated Toxicity2                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 3 or Severe                                                     | Toxicity resolves to Grade 0-1                                                                                                             | to reduce corticosteroid to 10 mg or less of prednisone or equivalent  per day within 12 weeks.                                                                      |
| 4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | Permanently discontinue                                         | Permanently discontinue                                                                                                                    |                                                                                                                                                                      |
| Note: Permanently discontinue for any severe or Grade 3 drug-related AE that recurs or any life-threatening event. 1 For patients with liver metastasis who begin treatment with Grade 2 AST or ALT, if AST or ALT increases by greater than or equal to 50% relative to baseline  and lasts for at least 1 week then patients should be discontinued.  2 Patients with intolerable or persistent Grade 2 drug-related AE may hold study medication at physician discretion. Permanently discontinue study drug for  persistent Grade 2 adverse reactions for which treatment with study drug has been held, that do not recover to Grade 0-1 within 12 weeks of the last dose. |                                                                 |                                                                                                                                            |                                                                                                                                                                      |  
Dosing interruptions are permitted in the case of medical / surgical events or logistical reasons not related to study therapy (e.g., elective surgery, unrelated medical events, patient vacation, and/or holidays). Subjects should be placed back on study therapy within 3 weeks of the scheduled interruption, unless otherwise discussed with the Sponsor. The reason for interruption should be documented in the patient's study record. Dose reductions of pembrolizumab are not permitted.
4.0 background & rationale
5.2.2 timing of dose administration

Trial treatment should be administered on Day 1 of each cycle after all procedures/assessments have been completed as detailed on the Study Calendar (Section 6.0). Trial treatment may be administered up to 3 days before or after the scheduled Day 1 of each cycle due to administrative reasons. All pembrolizumab treatment will be administered on an outpatient basis. Palliative radiotherapy is permitted to be delivered as an inpatient if in line with patient standard-of-care and after discussion with the study PI. Pembrolizumab 200 mg will be administered as a 30 minute IV infusion every 3 weeks. Sites should make every effort to target infusion timing to be as close to 30 minutes as possible. However, given the variability of infusion pumps from site to site, a window of -5 minutes and +10 minutes is permitted (i.e., infusion time is 30 minutes: -5 min/+10 min). The Pharmacy Manual contains specific instructions for the preparation of the pembrolizumab infusion fluid and administration of infusion solution.
4.0 background & rationale
5.2.3 external beam radiotherapy 5.2.3.1

The intent of treatment is to deliver a palliative course of radiotherapy to a total dose of 30 Gy in 10 fractions to the symptomatic primary disease sites in the esophageal, GE junction, or gastric areas or one of the metastases. Both 3D conformal radiotherapy and IMRT are allowed. Megavoltage equipment with effective photon energies ≥6MV is required. Technique: 3D conformal using opposed AP-PA portals or multifield techniques, such as AP, PA and opposed lateral fields or IMRT are recommended. ICRU-50 and ICRU-62 prescription methods and nomenclature shall be used in this trial. Tightly contoured targets should be used to spare as much bone marrow, small bowel, liver, heart, lung and kidney as possible. The prescription volume is the planning target volume (PTV). The total dose is 30 Gy in 10 fractions. A minimum of 90% of the PTV will receive 30 Gy. No more than 10% of the PTV shall receive greater than 35 Gy.
4.0 background & rationale
5.2.3.2 localization simulation and immobilization

Prior to the simulation, all pertinent radiographs, operative notes, and other diagnostic procedures such as endoscopic findings should be reviewed. This will allow an informed determination of target volume and treatment field borders. Simulation is required for all patients and should be performed with the patient positioned in an individualized immobilization device in the treatment position on a flat hard table and it is better in the supine position. Simulation must be performed on a diagnostic quality radiation Version: 04 therapy simulator, which reproduces the geometry of the treatment machine. Oral contrast can be used to help outlining the target volume in the esophageal/GE junction/gastric areas. CTbased treatment planning is required for this study. The planning CT should encompass the entire thoracic cavity for esophageal/GE junction cancer and the abdominal to a level below the bottom of the kidneys for gastric cancer. A maximum slice thickness of 3-5 mm is required through regions of the gross tumor volume (GTV).
4.0 background & rationale
5.2.3.3 treatment planning and target

Gross Target Volume (GTV): The GTV is defined as the primary tumor in the esophageal/GE junction/gastric areas, the grossly enlarged lymph nodes, or the gross metastatic sites requiring a palliative course of radiotherapy. Clinical Target Volume (CTV): Since the intent of radiotherapy is for palliation, there is no need to define a CTV for treatment. Planning Target Volume (PTV): Margins shall be added to the GTV for set up error and movement as PTV. This expansion could be 0.5 to 2 cm and does not need to be uniform in all dimensions. 4DCT scan is allowed to customize PTV expansion. 3D conformal radiotherapy or IMRT should be planned to optimize the PTV coverage and a minimum of 90% of the PTV shall receive 30 Gy. No more than 10% of the PTV shall receive greater than 35 Gy. IMRT can be delivered by tomotherapy or TrueBeam using RapidArc technique.
4.0 background & rationale
5.2.3.4 critical structures and compliance

Organs at risk including lungs, liver, heart, kidneys and spinal cord shall be contoured. Dose constraints must follow the standard guidelines. The treating physician must carefully consider the tolerance dose/volume to each critical normal structure. It is recommended to reduce doses to lung and heart as much as possible.  
x Lung: mean dose ≤ 20 Gy, V30 ≤ 20%, V20 ≤ 25%, V10 ≤ 40% and V5 ≤ 50% x Heart: mean dose ≤ 25 Gy, V30 ≤ 30%
x Kidney: V20 ≤ 30% x Liver: mean dose ≤ 20 Gy, V30 ≤ 30%
4.0 background & rationale
5.2.3.5 radiotherapy adverse events

Adverse effects related to radiation therapy will be recorded. These include nausea/vomiting, diarrhea, poor appetite, weight loss, fatigue, skin erythema, esophagitis, carditis, pneumonitis, myelosuppression, myelitis, late pulmonary fibrosis, and esophageal stricture.
4.0 background & rationale
5.3 concomitant medications/vaccinations (allowed &

Medications or vaccinations specifically prohibited in the exclusion criteria are not allowed during the ongoing trial. If there is a clinical indication for one of these or other medications or vaccinations specifically prohibited during the trial, discontinuation from trial therapy or vaccination may be required. The investigator should discuss any questions regarding this with the Merck Clinical team. The final decision on any supportive therapy or vaccination rests with the investigator and/or the subject's primary physician.
4.0 background & rationale
5.3.1 acceptable concomitant medications

All treatments that the investigator considers necessary for a subject's welfare may be administered at the discretion of the investigator in keeping with the community standards of medical care. All concomitant medication will be recorded on the case report form (CRF) including all prescription, over-the-counter (OTC), herbal supplements, and IV medications and fluids. If changes occur during the trial period, documentation of drug dosage, frequency, route, and date may also be included on the CRF. All concomitant medications received within 28 days before the first dose of trial treatment and 30 days after the last dose of trial treatment should be recorded. Concomitant medications administered after 30 days after the last dose of trial treatment should be recorded for SAEs and ECIs as defined in Section 8.0.
4.0 background & rationale
5.3.2 prohibited concomitant medications

Subjects are prohibited from receiving the following therapies during the Screening and Treatment Phase (including retreatment for post-complete response relapse) of this trial:
x Antineoplastic systemic chemotherapy or biological therapy  
x Immunotherapy not specified in this protocol
x Chemotherapy not specified in this protocol x Investigational agents other than pembrolizumab x Radiation therapy outside of the clinical target volume of the index target lesion o Note: Radiation therapy to a symptomatic lesion other than the index target lesion or to the brain may be allowed at the investigator's discretion if the radiation course occurs after radiation has completed to the index target lesion.  
x Live vaccines within 30 days prior to the first dose of trial treatment and while participating in the trial. Examples of live vaccines include, but are not limited to, the following: measles, mumps, rubella, varicella/zoster, yellow fever, rabies, BCG, and typhoid vaccine.  
x Systemic glucocorticoids for any purpose other than to modulate symptoms from an event of clinical interest of suspected immunologic etiology. The use of physiologic doses of corticosteroids may be approved after consultation with the Sponsor.
Subjects who, in the assessment by the investigator, require the use of any of the aforementioned treatments for clinical management should be removed from the trial. Subjects may receive other medications that the investigator deems to be medically necessary. The Exclusion Criteria describes other medications which are prohibited in this trial. There are no prohibited therapies during the Post-Treatment Follow-up Phase.
4.0 background & rationale
5.4 rescue medications & supportive

Subjects should receive appropriate supportive care measures as deemed necessary by the treating investigator. Suggested supportive care measures for the management of adverse events with potential immunologic etiology are outlined below and in greater detail in the ECI guidance document. Where appropriate, these guidelines include the use of oral or intravenous treatment with corticosteroids as well as additional anti-inflammatory agents if symptoms do not improve with administration of corticosteroids. Note that several courses of steroid tapering may be necessary as symptoms may worsen when the steroid dose is decreased. For each disorder, attempts should be made to rule out other causes such as metastatic disease or bacterial or viral infection, which might require additional supportive care. The treatment guidelines are intended to be applied when the investigator determines the events to be related to pembrolizumab. Note: if after the evaluation the event is determined not to be related, the investigator is instructed to follow the ECI reporting guidance but does not need to follow the treatment guidance (as outlined in the ECI guidance document). Refer to Section 5.2.1 for dose modification. It may be necessary to perform conditional procedures such as bronchoscopy, endoscopy, or skin photography as part of evaluation of the event. Suggested conditional procedures, as appropriate, can be found in the ECI guidance document.
4.0 background & rationale
x pneumonitis

o For **Grade 2 events**, treat with systemic corticosteroids. When symptoms improve to Grade 1 or less, steroid taper should be started and continued over no less than 4 weeks.  
o For **Grade 3-4 events**, immediately treat with intravenous steroids.  
Administer additional anti-inflammatory measures, as needed.  
o Add prophylactic antibiotics for opportunistic infections in the case of prolonged steroid administration.
4.0 background & rationale
x diarrhea/colitis

Subjects should be carefully monitored for signs and symptoms of enterocolitis (such as diarrhea, abdominal pain, blood or mucus in stool, with or without fever) and of bowel perforation (such as peritoneal signs and ileus).  
o All subjects who experience diarrhea/colitis should be advised to drink liberal quantities of clear fluids. If sufficient oral fluid intake is not feasible, fluid and electrolytes should be substituted via IV infusion. For Grade 2 or higher diarrhea, consider GI consultation and endoscopy to confirm or rule out colitis.  
o For **Grade 2 diarrhea/colitis** that persists greater than 3 days, administer oral corticosteroids.  
o For **Grade 3 or 4 diarrhea/colitis** that persists > 1 week, treat with intravenous steroids followed by high dose oral steroids.  
o When symptoms improve to Grade 1 or less, steroid taper should be started and continued over no less than 4 weeks.  
x **Type 1 diabetes mellitus (if new onset, including diabetic ketoacidosis [DKA]) or**
≥ Grade 3 Hyperglycemia**, if associated with ketosis (ketonuria) or metabolic** acidosis (DKA)
o For T1DM or **Grade 3-4** Hyperglycemia Insulin replacement therapy is recommended for Type I diabetes mellitus and for Grade 3-4 hyperglycemia associated with metabolic acidosis or ketonuria.  
Evaluate patients with serum glucose and a metabolic panel, urine ketones, glycosylated hemoglobin, and C-peptide.
4.0 background & rationale
x hypophysitis

o For **Grade 2** events, treat with corticosteroids. When symptoms improve to Grade 1 or less, steroid taper should be started and continued over no less than 4 weeks. Replacement of appropriate hormones may be required as the steroid dose is tapered.  
o For **Grade 3-4** events, treat with an initial dose of IV corticosteroids followed by oral corticosteroids. When symptoms improve to Grade 1 or less, steroid taper should be started and continued over no less than 4 weeks. Replacement of appropriate hormones may be required as the steroid dose is tapered.
4.0 background & rationale
x hyperthyroidism or hypothyroidism

Thyroid disorders can occur at any time during treatment. Monitor patients for changes in thyroid function (at the start of treatment, periodically during treatment, and as indicated based on clinical evaluation) and for clinical signs and symptoms of thyroid disorders.  
o **Grade 2** hyperthyroidism events (and **Grade 2-4** hypothyroidism):
In hyperthyroidism, non-selective beta-blockers (e.g. propranolol) are suggested as initial therapy.  
In hypothyroidism, thyroid hormone replacement therapy, with levothyroxine or liothyroinine, is indicated per standard of care.  
o **Grade 3-4** hyperthyroidism Treat with an initial dose of IV corticosteroid followed by oral corticosteroids. When symptoms improve to Grade 1 or less, steroid taper should be started and continued over no less than 4 weeks. Replacement of appropriate hormones may be required as the steroid dose is tapered.  
x **Hepatic**:
o For **Grade 2** events, monitor liver function tests more frequently until returned to baseline values (consider weekly).  
Treat with IV or oral corticosteroids o For **Grade 3-4** events, treat with intravenous corticosteroids for 24 to 48 hours.  
o When symptoms improve to Grade 1 or less, a steroid taper should be started and continued over no less than 4 weeks.
4.0 background & rationale
x renal failure or nephritis

o For **Grade 2** events, treat with corticosteroids. o For **Grade 3-4** events, treat with systemic corticosteroids.  
o When symptoms improve to Grade 1 or less, steroid taper should be started and continued over no less than 4 weeks.  
x **Management of Infusion Reactions**: Signs and symptoms usually develop during or shortly after drug infusion and generally resolve completely within 24 hours of completion of infusion. Table 3 below shows treatment guidelines for subjects who experience an infusion reaction associated with administration of pembrolizumab (MK-3475).  
| NCI CTCAE Grade                                                                                                                                 | Treatment                                                                                                                                         | Premedication at subsequent  dosing                                                                  |
|-------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------|
| Grade 1  Mild reaction; infusion interruption  not indicated; intervention not  indicated                                                       | Increase monitoring of vital signs as medically  indicated until the subject is deemed medically  stable in the opinion of the investigator.      | None                                                                                                 |
| Grade 2  Requires infusion interruption but  responds promptly to symptomatic  treatment (e.g., antihistamines,  NSAIDS, narcotics, IV fluids); | Stop Infusion and monitor symptoms.  Additional appropriate medical therapy may  include but is not limited to: IV fluids  Antihistamines  NSAIDS | Subject may be premedicated 1.5h  (± 30 minutes) prior to infusion of  pembrolizumab (MK-3475) with: |
| IRB Protocol No. 16099                                                                                                                          | Version Date: 10/16/2019                                                                                                                          |                                                                                                      |
| Version: 04                                                                                                                                     |                                                                                                                                                   |                                                                                                      |
4.0 background & rationale
table 3 infusion reaction treatment

| NCI CTCAE Grade                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | Treatment                                                                                                                                                                                                                                                        | Premedication at subsequent  dosing   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------|
| prophylactic medications indicated for                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | Acetaminophen                                                                                                                                                                                                                                                    |                                       |
| < =24 hrs                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | Narcotics                                                                                                                                                                                                                                                        |                                       |
| Increase monitoring of vital signs as medically  indicated until the subject is deemed medically  stable in the opinion of the investigator. If symptoms resolve within one hour of stopping  drug infusion, the infusion may be restarted at  50% of the original infusion rate (e.g., from 100  mL/hr to 50 mL/hr). Otherwise dosing will be  held until symptoms resolve and the subject  should be premedicated for the next scheduled  dose. Subjects who develop Grade 2 toxicity despite  adequate premedication should be  permanently discontinued from further trial  treatment administration. | Diphenhydramine 50 mg po or IV  (or equivalent dose of  antihistamine).  Acetaminophen 500-1000 mg po  (or equivalent dose of antipyretic).                                                                                                                      |                                       |
| Grades 3 or 4                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | Stop Infusion.  Additional appropriate medical therapy may  include but is not limited to:  IV fluids  Antihistamines  NSAIDS  Acetaminophen  Narcotics  Oxygen  Pressors  Corticosteroids  Epinephrine                                                          | No subsequent dosing                  |
| Grade 3: Prolonged (i.e., not rapidly responsive  to symptomatic medication and/or  brief interruption of infusion);  recurrence of symptoms following  initial improvement; hospitalization  indicated for other clinical sequelae  (e.g., renal impairment, pulmonary  infiltrates) Grade 4: Life-threatening; pressor or ventilatory  support indicated                                                                                                                                                                                                                                                | Increase monitoring of vital signs as medically  indicated until the subject is deemed medically  stable in the opinion of the investigator. Hospitalization may be indicated. Subject is permanently discontinued from  further trial treatment administration. |                                       |
| Appropriate resuscitation equipment should be available in the room and a physician readily available during the period of drug administration.                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                  |                                       |
4.0 background & rationale
5.5 diet/activity/other considerations 5.5.1 diet

Subjects should maintain a normal diet unless modifications are required to manage an AE such as diarrhea, nausea or vomiting.
4.0 background & rationale
5.5.2 contraception

Pembrolizumab may have adverse effects on a fetus in utero. Furthermore, it is not known if pembrolizumab has transient adverse effects on the composition of sperm. Non-pregnant, nonbreast-feeding women may be enrolled if they are willing to use 2 methods of birth control or are considered highly unlikely to conceive. Highly unlikely to conceive is defined as 1) surgically sterilized, or 2) postmenopausal (a woman who is ≥45 years of age and has not had menses for greater than 1 year will be considered postmenopausal), or 3) not heterosexually active for the duration of the study. The two birth control methods can be either two barrier Version: 04 methods or a barrier method plus a hormonal method to prevent pregnancy. Subjects should start using birth control from study Visit 1 throughout the study period up to 120 days after the last dose of study therapy. The following are considered adequate barrier methods of contraception: diaphragm, condom (by the partner), copper intrauterine device, sponge, or spermicide. Appropriate hormonal contraceptives will include any registered and marketed contraceptive agent that contains an estrogen and/or a progestational agent (including oral, subcutaneous, intrauterine, or intramuscular agents). Subjects should be informed that taking the study medication may involve unknown risks to the fetus (unborn baby) if pregnancy were to occur during the study. In order to participate in the study they must adhere to the contraception requirement (described above) for the duration of the study and during the follow-up period defined in section 8.6-Reporting of Pregnancy and Lactation to Merck. If there is any question that a subject will not reliably comply with the requirements for contraception, that subject should not be entered into the study.
4.0 background & rationale
5.5.3 use in pregnancy

If a subject inadvertently becomes pregnant while on treatment with pembrolizumab, the subject will immediately be removed from the study. The site will contact the subject at least monthly and document the subject's status until the pregnancy has been completed or terminated. The outcome of the pregnancy will be reported to the Sponsor and to Merck without delay and within 24 hours to the Sponsor and within 2 working days to Merck if the outcome is a serious adverse experience (e.g., death, abortion, congenital anomaly, or other disabling or life-threatening complication to the mother or newborn). The study investigator will make every effort to obtain permission to follow the outcome of the pregnancy and report the condition of the fetus or newborn to the Sponsor. If a male subject impregnates his female partner the study personnel at the site must be informed immediately and the pregnancy reported to the Sponsor and to Merck and followed as described above and in Section 8.6.
4.0 background & rationale
5.5.4 use in nursing women

It is unknown whether pembrolizumab is excreted in human milk. Since many drugs are excreted in human milk, and because of the potential for serious adverse reactions in the nursing infant, subjects who are breast-feeding are not eligible for enrollment.
4.0 background & rationale
5.6 subject withdrawal/discontinuation criteria

Subjects may withdraw consent at any time for any reason or be dropped from the trial at the discretion of the investigator should any untoward effect occur. In addition, a subject may be withdrawn by the investigator or the Sponsor if enrollment into the trial is inappropriate, the trial plan is violated, or for administrative and/or other safety reasons. Specific details regarding discontinuation or withdrawal are provided in Section 7.1.4 - Other Procedures. Version: 04 A subject must be discontinued from the trial for any of the following reasons:  
x The subject or legal representative (such as a parent or legal guardian) withdraws consent.  
x Confirmed radiographic disease progression
Note: For unconfirmed radiographic disease progression, please see Section 5.2.2 Note: A subject may be granted an exception to continue on treatment with confirmed radiographic progression if clinically stable or clinically improved, please see Section 7.1.2.6.2 x Unacceptable adverse experiences as described in Section 5.2.1.2 x Intercurrent illness that prevents further administration of treatment x Investigator's decision to withdraw the subject x The subject has a confirmed positive serum pregnancy test x Noncompliance with trial treatment or procedure requirements x The subject is lost to follow-up  
x Completed 24 months of uninterrupted treatment with pembrolizumab or 35 administrations of study medication, whichever is later.
Note: 24 months of study medication is calculated from the date of first dose. Subjects who stop pembrolizumab after 24 months may be eligible for up to one year of additional study treatment if they progress after stopping study treatment provided they meet the requirements detailed in Section 7.1.5.5
4.0 background & rationale
x administrative reasons

The End of Treatment and Follow-up visit procedures are listed in Section 6.0 (Study Calendar) and Section 7.1.5 (Visit Requirements). After the end of treatment, each subject will be followed for 30 days for adverse event monitoring (serious adverse events will be collected for 90 days after the end of treatment as described in Section 8.0). Subjects who discontinue for reasons other than progressive disease will have post-treatment follow-up for disease status until disease progression, initiating a non-study cancer treatment, withdrawing consent or becoming lost to follow-up. After documented disease progression each subject will be followed by telephone for overall survival until death, withdrawal of consent, or the end of the study, whichever occurs first.
4.0 background & rationale
5.6.1 discontinuation of study therapy

Discontinuation of treatment may be considered for subjects who have attained a confirmed CR that have been treated for at least 24 weeks with pembrolizumab and had at least two treatments with pembrolizumab beyond the date when the initial CR was declared. Subjects who then experience radiographic disease progression may be eligible for up to one year of additional treatment with pembrolizumab via the Second Course Phase at the discretion of the investigator if no cancer treatment was administered since the last dose of pembrolizumab, the subject meets the safety parameters listed in the Inclusion/Exclusion criteria, and the trial is open. Subjects will resume therapy at the same dose and schedule at the time of initial discontinuation. Additional details are provided in Section 7.1.5.5.
4.0 background & rationale
5.7 clinical criteria for early

Early trial termination will be the result of the criteria specified below: 1. Quality or quantity of data recording is inaccurate or incomplete 2. Poor adherence to protocol and regulatory requirements  
3. Incidence or severity of adverse drug reaction in this or other studies indicates a potential health hazard to subjects
4. Plans to modify or discontinue the development of the study drug In the event of Merck decision to no longer supply study drug, ample notification will be provided so that appropriate adjustments to subject treatment can be made.  
  
Version: 04 6.0 STUDY CALENDAR 6.1 Initial Treatment Phase **Trial Period:**  
  
Version: 04
IRB Protocol No. 16099 Version Date: 10/16/2019  
  
  
  
At time of Discon  
| Safety  Followup                    | 30 days  post  discon  At time  of  Discon   |
|--------------------|----------------------------------------------|
| End of  Treat ment |                                              |  
| a. Patients will continue pembrolizumab for a maximum of 35 cycles for first course of therapy if no evidence of disease progression or intolerable toxicity.  b. In patients who discontinue study therapy without documented disease progression, every effort should be made to continue monitoring disease status by radiologic imaging  every 6 weeks (± 7 days) until 1) the start of new anti-cancer treatment, 2) disease progression on imaging, 3) death, or 4) the end of the study, whichever occurs first.   | c. After the start of new anti-cancer treatment or documented disease progression by imaging, the patient should be contacted by telephone every 12 weeks to assess for survival  status.   | d. Laboratory tests and ECOG PS are to be performed within 10 days prior to the first dose of trial treatment.   | e. Palliative radiotherapy to a total dose of 30 Gy to the primary tumor will be delivered in 3 Gy fractions daily with the exception of weekends and holidays. The first fraction  of radiation should be given on C1D1 prior to administration of pembrolizumab. Radiation may continue into cycle 2 if delayed for management of toxicity or administrative  reasons.   | f. For women of reproductive potential, a urine pregnancy test will be performed within 72 hours prior to the first dose of trial treatment. A serum test may be considered if  urine test is not appropriate or inconclusive.   | g. Thyroid function tests should be collected at screening and every 6 weeks in concordance with day 1 of even-numbered cycles.  h. Serum CEA should be collected at screening and every 6 weeks in concordance with day 1 of odd-numbered cycles.  i. Tumor imaging should be performed every 6 weeks through the first 6 cycles, then subsequently performed every 9 weeks thereafter. For patients who complete 35 cycles of  therapy or 2 years of follow up without evidence of progression, scans can be spaced out to every 12-24 weeks at the discretion of the treating physician. The exception will  be patients who demonstrate PD, PR, or CR by RECIST 1.1, in which event the next imaging will be performed at 6 weeks for confirmation. Refer to Section 7.1.2.6.2 for  details.   | j. Tumor biopsies will be performed prior to cycle 1/day 1, and at 21 days (± 3 days) after completion of palliative radiotherapy. Biopsies will be performed of metastatic sites  amenable to access by CT or ultrasound-guidance. Malignant ascites accessible by ultrasound guidance will also be eligible as tumor biopsy specimens. For patients receiving  RT to a metastatic site and only the primary tumor is accessible to biopsy, these will be obtained by endoscopy.  k. Blood/stool/oral swab collection for correlative studies will be collected at screening assessment, at 21 days (± 3 days) after completion of palliative radiotherapy, at timepoint  of first progression by RECIST (if applicable and continued on protocol therapy), and at end of treatment.   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|  
Version: 04  
Version Date: 10/16/2019 IRB Protocol No. 16099  
  
6.2 **Second Course Phase**  
| Survival  FollowUpc Follow  Up  Visitsb Safety  Followup Last  Dose  Treatment Cycle: C1/D1 C2/D1 C3/D1 C4D1 C5D1 C6+D1a                                                                                                                         | a. Patients will continue pembrolizumab for a maximum of 17 cycles for second course of therapy if no evidence of disease progression or intolerable toxicity.  b. In patients who discontinue study therapy without documented disease progression, every effort should be made to continue monitoring disease status by  radiologic imaging every 6 weeks (± 7 days) until 1) the start of new anti-cancer treatment, 2) disease progression on imaging, 3) death, or 4) the end of the  study, whichever occurs first.   | c. After the start of new anti-cancer treatment or documented disease progression by imaging, the patient should be contacted by telephone every 12 weeks to  assess for survival status.   | d. Thyroid function tests should be collected at C1/D1 and every 6 weeks in concordance with day 1 of odd-numbered cycles.   | e. Serum CEA should be collected at C1D1 and every 6 weeks in concordance with day 1 of odd-numbered cycles.  f. Tumor imaging should be performed every 6 weeks through the first 6 cycles, then subsequently performed every 9 weeks thereafter. For patients who  complete 35 cycles of second course therapy or 2 years of follow up without evidence of progression, scans can be spaced out to every 12-24 weeks at the  discretion of the treating physician. The exception will be patients who demonstrate PD, PR, or CR by RECIST 1.1, in which event the next imaging will be  performed at 6 weeks for confirmation. Refer to Section 7.1.2.6.2 for details.   |
|-------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Every  12  weeks                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                             |                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Every 6  weeks  post  discon  30 days  post  discon  At time  of  Discon  Scheduling Window (Days): ± 3 ± 3 ± 3 ± 3 ± 3 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                             |                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Post-Treatment                                                                                                          | X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | Xd X                                                                                                                                                                                        |                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| End of  Treat ment                                                                                                      | X X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | Xe                                                                                                                                                                                          | Xf                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| X                                                                                                                       | X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | X                                                                                                                                                                                           | X                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Treatment Cycles                                                                                                        | X X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | X                                                                                                                                                                                           | X                                                                                                                            | Efficacy Measurements  Tumor Imagingf X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| X X                                                                                                                     | X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | T3, FT4 and TSHd X                                                                                                                                                                          | Serum carcinoembryonic antigen (CEA)e X                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Comprehensive Serum Chemistry Panel                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                             |                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Trial Period:                                                                                                           | Urinalysis                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                             |                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |  
IRB Protocol No. 16099 Version Date: 10/16/2019
4.0 background & rationale
7.0 trial procedures 7.1 trial

The Study Calendar - Section 6.0 summarizes the trial procedures to be performed at each visit.  
Individual trial procedures are described in detail below. It may be necessary to perform these procedures at unscheduled time points if deemed clinically necessary by the investigator. Furthermore, additional evaluations/testing may be deemed necessary by the Sponsor and/or Merck for reasons related to subject safety. In some cases, such evaluation/testing may be potentially sensitive in nature (e.g., HIV, Hepatitis C, etc.), and thus local regulations may require that additional informed consent be obtained from the subject. In these cases, such evaluations/testing will be performed in accordance with those regulations.
4.0 background & rationale
7.1.1 administrative procedures 7.1.1.1 informed

The Investigator must obtain documented consent from each potential subject prior to participating in the clinical trial. Consent must be documented by the subject's dated signature or by the subject's legally acceptable representative's dated signature on a consent form along with the dated signature of the person conducting the consent discussion. A copy of the signed and dated consent form should be given to the subject before participation in the trial. The initial informed consent form, any subsequent revised written informed consent form and any written information provided to the subject must receive the IRB's approval/favorable opinion in advance of use. The subject or his/her legally acceptable representative should be informed in a timely manner if new information becomes available that may be relevant to the subject's willingness to continue participation in the trial. The communication of this information will be provided and documented via a revised consent form or addendum to the original consent form that captures the subject's dated signature or by the subject's legally acceptable representative's dated signature. Specifics about a trial and the trial population will be added to the consent form template at the protocol level. The informed consent will adhere to IRB requirements, applicable laws and regulations and COH requirements.
4.0 background & rationale
7.1.1.2 inclusion/exclusion criteria

All inclusion and exclusion criteria will be reviewed by the investigator or qualified designee to ensure that the subject qualifies for the trial.
4.0 background & rationale
7.1.1.3 medical history

A medical history will be obtained by the investigator or qualified designee. Medical history will include all active conditions, and any condition diagnosed within the prior 10 years that are considered to be clinically significant by the Investigator. Details regarding the disease for which the subject has enrolled in this study will be recorded separately and not listed as medical history.
4.0 background & rationale
7.1.1.4 prior and concomitant medications

The investigator or qualified designee will review prior medication use, including any protocol-specified washout requirement, and record prior medication taken by the subject within 28 days before starting the trial. Treatment for the disease for which the subject has enrolled in this study will be recorded separately and not listed as a prior medication.
4.0 background & rationale
concomitant medications

The investigator or qualified designee will record medication, if any, taken by the subject during the trial. All medications related to reportable SAEs and ECIs should be recorded as defined in Section 8.0.
4.0 background & rationale
7.1.1.5 disease details and treatments

The investigator or qualified designee will obtain prior and current details regarding disease status.
4.0 background & rationale
prior treatment details

The investigator or qualified designee will review all prior cancer treatments including systemic treatments, radiation and surgeries.
4.0 background & rationale
subsequent anti-cancer therapy status

The investigator or qualified designee will review all new anti-neoplastic therapy initiated after the last dose of trial treatment. If a subject initiates a new anti-cancer therapy within 30 days after the last dose of trial treatment, the 30 day Safety Follow-up visit must occur before the first dose of the new therapy. Once new anti-cancer therapy has been initiated the subject will move into survival follow-up.
4.0 background & rationale
7.1.1.6 assignment of screening number

All consented subjects will be given a unique City of Hope screening number that will be used to identify the subject for all procedures that occur prior to treatment allocation. Each subject will be assigned only one screening number. Screening numbers must not be re-used for different subjects. Any subject who is screened multiple times will retain the original screening number assigned at the initial screening visit.
4.0 background & rationale
7.1.1.7 trial compliance (medication/diet/activity/other)

Interruptions from the protocol specified treatment for greater than 12 weeks between treatments require consultation between the investigator and the Sponsor and written documentation of the collaborative decision on subject management. Administration of trial medication will be witnessed by the investigator and/or trial staff. The total volume of pembrolizumab infused will be compared to the total volume prepared to determine compliance with each dose of pembrolizumab administered. The instructions for preparing and administering pembrolizumab are provided in the Pharmacy Manual. Treatment with standard of care palliative radiotherapy will be prepared and administered as per the approved Department of Radiation Oncology and institutional guidelines.
4.0 background & rationale
7.1.2 clinical procedures/assessments 7.1.2.1 adverse

The investigator or qualified designee will assess each subject to evaluate for potential new or worsening AEs as specified in the Study Calendar and more frequently if clinically indicated.  
Adverse experiences will be graded and recorded throughout the study and during the followup period according to NCI CTCAE Version 4.0. Toxicities will be characterized in terms regarding seriousness, causality, toxicity grading, and action taken with regard to trial treatment. For subjects receiving treatment with pembrolizumab all AEs of unknown etiology associated with pembrolizumab exposure should be evaluated to determine if it is possibly an event of clinical interest (ECI) of a potentially immunologic etiology (termed immune-related adverse events, or irAEs); see the separate ECI guidance document in the Appendix regarding the identification, evaluation and management of potential irAEs. Please refer to Section 8.0 for detailed information regarding the assessment and recording of AEs.
4.0 background & rationale
7.1.2.2 full physical exam

The investigator or qualified designee will perform a complete physical exam during the screening period. Clinically significant abnormal findings should be recorded as medical history. A full physical exam should be performed during screening,
4.0 background & rationale
7.1.2.3 directed physical exam

For cycles that do not require a full physical exam per the Study Calendar, the investigator or qualified designee will perform a directed physical exam as clinically indicated prior to trial treatment administration.
4.0 background & rationale
7.1.2.4 vital signs

The investigator or qualified designee will take vital signs at screening, prior to the administration of each dose of trial treatment and at treatment discontinuation as specified in the Study Calendar (Section 6.0). Vital signs should include temperature, pulse, respiratory rate, weight and blood pressure. Height will be measured at screening only.
4.0 background & rationale
7.1.2.5 eastern cooperative oncology group

The investigator or qualified designee will assess ECOG status (see Appendix 1) at screening, prior to the administration of each dose of trial treatment and discontinuation of trial treatment as specified in the Study Calendar.
4.0 background & rationale
7.1.2.6 tumor imaging and assessment

Tumor imaging may be performed by computed tomography (CT; preferred) or magnetic resonance imaging (MRI), but the same imaging technique should be used in a subject throughout the trial. CT scan is the more commonly used modality and is preferred for the majority of patients. An MRI can be utilized if clinically appropriate.
4.0 background & rationale
7.1.2.6.1 initial tumor imaging

To meet screening criteria, initial tumor imaging must be performed within 21 days prior to start of cycle 1, day 1. This scan will be considered the baseline assessment for the study. The site study team must review pre-trial images to confirm the subject has at least one target lesion (i.e. meets measurability requirements) per RECIST 1.1. Scans performed as part of routine clinical management are acceptable for use as the baseline scan if they are of diagnostic quality, include all required anatomy, and performed within 21 days prior to start of treatment.
4.0 background & rationale
7.1.2.6.2 tumor imaging on study

The first on-study imaging assessment should be performed at 6 weeks (42 days ± 7 days) after the first dose of trial treatment. Subsequent imaging should be performed every 6 weeks (42 days ± 7 days) through the first 6 cycles. After 6 cycles, imaging will be pursued every 9 weeks (63 days ± 7 days) until demonstration of PD, PR, or CR, in which event imaging will be performed in 6 weeks for confirmation. RECIST 1.1 may not provide an accurate assessment of immunotherapeutic agents such as pembrolizumab. Immune-related RECIST (irRECIST) is RECIST 1.1 adapted as described below to account for the unique tumor response seen with immunotherapeutics.  
Patients with 1st radiologic assessment of PD by RECIST 1.1 may continue treatment if clinically stable as per Table 4. If the repeat scan confirms PD, patients will be discontinued from treatment. Exception can be made if the Investigator feels the patient is deriving benefit from treatment and after discussion with the study PI and Sponsor. Subsequent imaging should be pursued every 6 weeks until demonstration of confirmed PR or CR in which event imaging will then be conducted every 9 weeks if a patients has completed at least 6 cycles of pembrolizumab. Imaging may be more frequent if clinically indicated.  
Clinically stable is defined by the following criteria:
x Absence of signs and symptoms indicating disease progression x No decline in ECOG performance status x Absence of rapid progression of disease x Absence of progressive tumor at critical anatomical sites (e.g., cord compression)
requiring urgent alternative medical intervention
4.0 background & rationale
table 4 imaging and treatment

| Clinically Stable                              | Clinically Unstable                       |                                                                                                      |                                                          |                        |
|------------------------------------------------|-------------------------------------------|------------------------------------------------------------------------------------------------------|----------------------------------------------------------|------------------------|
| Imaging                                        | Treatment                                 | Imaging                                                                                              | Treatment                                                |                        |
| 1st radiologic  evidence of PD  per RECIST 1.1 | Repeat imaging  at 6 weeks to  confirm PD | May continue  study treatment at  the Investigator's  discretion while  awaiting  confirmatory  scan | Repeat imaging  at ≥ 4 weeks to  confirm PD if  possible | Discontinue  treatment |
| Repeat scan                                    | No additional                             | Discontinue                                                                                          |                                                          |                        |
| confirms PD                                    | imaging required                          | treatment  (exception is  possible after  discussion with                                            | No additional                                            | N/A                    |
| imaging required                               |                                           |                                                                                                      |                                                          |                        |  
| the PI and  Sponsor)              |                                                                                                       |                                                              |                                                                                                       |                                                                                                                    |
|-----------------------------------|-------------------------------------------------------------------------------------------------------|--------------------------------------------------------------|-------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------|
| Repeat scan  shows SD, PR, or  CR | Continue  regularly  scheduled  imaging  assessments  every 6-9 weeks  dependent on  cycle of therapy | Continue study  treatment at the  Investigator's  discretion | Continue  regularly  scheduled  imaging  assessments  every 6-9 weeks  dependent on  cycle of therapy | May restart study  treatment if  condition has  improved and/or  clinically stable  per Investigator's  discretion |
4.0 background & rationale
7.1.2.7 tumor tissue collection and

Tumor biopsies will be performed during the Screening Phase and 21 days after completion of palliative radiotherapy. CT or ultrasound-guided biopsies will utilize 20-gauge core biopsy needles. As such tissue samples will be composed of both tumor cells and associated tumor stroma. Fresh tumor samples will be immediately delivered to the laboratory of Dr. Peter Lee for both ex vivo tumor/immune/stromal cell culture and expansion as well as histologic analyses. Patients with fresh malignant ascites collected by ultrasound guidance will also be immediately delivered to the lab for ex vivo tumor/immune/stromal cell culture and expansion alone.  
Dr. Lee's lab will utilize quantitative spatial image analysis to examine changes in tumor cellstromal interactions including CD4, CD8, Treg, and MDSC populations pre- and posttherapy.  
PD-L1 expression within the tumor, on cancer cells and stromal cells, will be analyzed by immunohistochemistry (IHC) locally in Dr. Lee's lab, as well as centrally through QualTek Laboratories. PD-1 expression on tumor infiltrating T cells will be analyzed by a combination of IHC and flow cytometry. Immune cell populations will be further analyzed via high dimensional flow cytometry to measure levels of Tregs and MDSCs. Dr. Lee's lab will also pursue multi-color IHC to determine influences of pembrolizumab+RT treatment on the magnitude and proximity of CD8 T cells to cancer cells within the tumor. Changes in the diversity of the T cell repertoire in both PD-1 positive and PD-1 negative T cell populations following pembrolizumab+RT treatment will be analyzed via deep sequencing of the TCR Vβ CDR3 region. Such changes in T cell repertoire can be suggestive of potential epitope spreading for anti-tumor antigens and reversal of tumor antigen-specific T cell anergy. Genomic analyses utilizing City of Hope's Integrative Genomics Core will also be performed on the corresponding cancer/stromal/immune cell populations via total RNA-seq for coding and non-coding RNAs (including miRNAs). Performance of these studies will require several highly developed techniques that have been routinely conducted in Dr. Peter Lee's lab. A prototype BD microfluidic FACS instrument allows for 12-color analysis of low cell numbers, thereby allowing maximal data acquisition out of small sample sizes. A powerful quantitative, spatial image analysis system will enable analysis of immune and cancer cells in tissues via 8-color histology. Lastly, Dr. Lee's lab has considerable expertise in TCR repertoire analysis via deep sequencing, which can yield information on T cell specificity to unknown antigens.
4.0 background & rationale
7.1.2.7.2 correlative studies blood sampling

Blood samples will be collected from an indwelling venous catheter or by venipuncture into three 7 mL green-top tubes (sodium or lithium heparin) at three timepoints: (1) Screening visit, (2) 21 days after completion of palliative radiotherapy, and (3) at the time of first progression by traditional RECIST1.1 (to capture potential pseudoprogression and only applicable for patients continued on treatment beyond progression), and at end of treatment. To prevent blood clotting, tubes will be inverted several times and then immediately placed on ice for transportation to the CICSL (Clinical Immunobiology Correlative Studies) processing laboratory. The whole blood should be processed within 4 hours of collection. While awaiting processing, the blood should be kept on a rocker set at low speed to mimic circulation and avoid clot formation.
4.0 background & rationale
sample processing in cicsl plasma

x For plasma preparation, anti-coagulated whole blood (two 7 mL green-top tubes) will be processed by centrifugation for 10 minutes at 1000 x g at 4OC. The resulting upper plasma layer from each tube will be drawn up sequentially into a sterile 5 mL syringe and pushed through a sterile 0.2/0.8 micron disposable filter (PALL Acrodisc PF, Cat. 4658). The filtered plasma will then be transferred in 500 μL aliquots into multiple appropriately-labeled Starstedt microfuge tubes (Starstedt Cat 72.692.005). To one aliquot, add 0.5 mL glycerol/0.02% sodium azide solution to dilute the plasma 50/50 v/v. Keep the diluted plasma sample at -20˚**C and do not freeze**. All the remaining plasma aliquots will be stored frozen at -80˚C until ready for testing.