Nivolumab, Ipilimumab and OTSGC-A24 Therapeutic Peptide Vaccine in Gastric Cancer - a Combination Immunotherapy Phase Ib Study.

Inclusion Criteria: 1. Histologically or cytologically confirmed inoperable or metastatic gastric cancer that has failed or demonstrated intolerance to standard therapy - which includes platinum or fluoropyrimidine or taxane based chemotherapy. 2. Patients must have measurable disease. 3. Age ≥ 21 years 4. ECOG performance status (PS) of 0 to 1 5. Life expectancy at least 3 months 6. Patients must have normal organ and marrow function as defined below: * Absolute neutrophil count (ANC) ≥ 1,500/mcL * Platelets ≥ 100,000/mcL * Total bilirubin within normal institutional limits * AST(SGOT)/ALT(SGPT) ≤ 2.5 X institutional upper limit of normal * Creatinine \<1.5x normal institutional limits 7. Patients must be HLA-A\*24:02 8. Patients must have recovered (\< grade 1) from all reversible treatment toxicity from prior chemotherapy, radiotherapy or surgery. 9. Ability to understand and the willingness to sign a written informed consent document. Exclusion Criteria: 1. Patients receiving any other investigational products 2. Patients who have previously received prior nivolumab or PD-/L1 blockade therapy 3. Active autoimmune disease requiring disease-modifying therapy. 4. Concurrent systemic steroid therapy higher than physiologic dose (equivalent of prednisolone 10mg daily) 5. Any form of active primary or secondary immunodeficiency. 6. History of significant gastrointestinal bleeding that required intervention within the prior 1 month is ineligible; inherited bleeding diathesis or coagulopathy. 7. Serious non healing wound and peptic ulcer disease 8. Previous history of intestinal perforation 9. Symptomatic central nervous system (CNS) metastasis 10. Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, uncontrolled hypertension (systolic \>160 mmHg and/or diastolic \>100 mmHg), symptomatic congestive heart failure, unstable angina pectoris, myocardial infarction/cerebrovascular event (≤ 6 months prior to study entry), cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements, long term systemic immunosuppressant or corticosteroid, and active viral hepatitis. 11. Women who are breast-feeding or pregnant are excluded from this study.