GEN-001 in Combination With Avelumab for Patients With PD-L1 Positive Gastric Cancer

Inclusion Criteria: * Histologically confirmed unresectable, recurrent, locally advanced or metastatic GC/Gastroesophageal Junction Adenocarcinoma * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Have adequate organ functions as defined in the protocol * Negative childbearing potential * Have experienced documented objective radiographic or clinical disease progression after 2 or above previous lines of standard therapy. * PD-L1 positive * Measurable disease as per RECIST v1.1 defined as at least 1 lesion * Estimated life expectancy of at least 3 months * Have ability to swallow and retain oral medication and no clinically significant gastrointestinal abnormalities Exclusion Criteria: * Previously received T-cell coregulatory protein inhibitors * Has clinically significant evidence of ascites by physical exam * Known prior severe hypersensitivity reactions to monoclonal antibodies or any component in their formulation * Has active autoimmune disease that has required systemic treatment in the past 2 years * Current use of immunosuppressive medication * Have an active infection requiring antibiotics, antifungal or antiviral agents or have received a course of antibiotics within 4 weeks * Has received a live vaccine within 4 weeks * Known history or any evidence of active for non-infectious pneumonitis * Prior solid organ or allogeneic stem cell transplantation * Has had any investigational or anti-tumor treatment within 4 weeks or 5 half-life periods of starting study treatment, had any major surgeries within 4 weeks * Has received proton pump inhibitors (PPIs) within 2 weeks * Has known active central nervous system (CNS) metastases and/or carcinomatous meningitis * Has clinically significant (i.e., active) cardiovascular disease * Has other persisting toxicities * Has other severe acute or chronic medical conditions including immune colitis, inflammatory bowel disease, or psychiatric conditions