Study of Suratadenoturev (OBP-301) in Combination With Pembrolizumab in Esophagogastric Adenocarcinoma

Inclusion Criteria:

• Histologically or cytologically confirmed advanced or metastatic gastric,gastroesophageal junction, or esophageal adenocarcinoma amenable to intra-tumoralinjection (i.e. at least 1 cm in size)

• Tumor must be PD-L1 positive as defined by a combined positive score (CPS), i.e. CPS ≥ 1 by approved, commercial diagnostic assay

• Tumor must be HER2 negative as determined by a CLIA-approved laboratory

Exclusion Criteria:

• Is currently participating and receiving study therapy or has participated in astudy of an investigational agent and received study therapy within 3 weeks of studyDay 1.

• Has an active autoimmune disease that has required systemic treatment in past 2years except replacement therapy (eg., thyroxine, insulin, or physiologiccorticosteroid)

• Has a diagnosis of immunodeficiency or is receiving systemic steroid therapy (greater than equivalent of 20 mg/day) or any other form of immunosuppressivetherapy within 7 days prior to study Day 1.

• Has known active central nervous system metastases and/or carcinomatous meningitis.

• Has had prior anti-cancer monoclonal antibody chemotherapy, targeted small moleculetherapy, or radiation therapy within 2 weeks prior to study Day 1, who has notrecovered from adverse events due to a previously administered agent.

• Has a known additional malignancy within 3 years before the first OBP-301administration that is progressing or requires active treatment, with the exceptionof prostate cancer controlled with androgen deprivation therapy.

• Has received a live vaccine or live-attenuated vaccine within 30 days before thefirst dose of study intervention. Administration of killed vaccines is allowed.

• Is known to have acute or chronic active hepatitis B virus (HBV), hepatitis C virus (HCV) or human immunodeficiency virus (HIV)

• Has a history of (non-infectious) pneumonitis/interstitial lung disease thatrequired steroids or has current pneumonitis/interstitial lung disease.

• Has an active infection requiring systemic therapy within 2 weeks of Day 1.

• Is unable to comply with protocol procedures

• Previous severe hypersensitivity (≥ Grade 3) to any monoclonal antibody

• Has not adequately recovered from major surgery or has ongoing surgicalcomplications.

• Has had an allogenic tissue/solid organ transplant

• Has certain uncontrolled illnesses

• Is pregnant or breastfeeding or planning to become pregnant or start breast feedingduring the study time period

• Is expecting to get someone else pregnant during the study time period