102Background: Angiogenesis and immunosuppression are hallmarks of tumor growth. This is the first study to combine R (anti-VEGFR2) with P (anti-PD-1) to simultaneously target both processes in the tumor microenvironment. Methods: This ongoing, multi-cohort, phase 1a/b trial (NCT02443324) enrolled pts with confirmed G/GEJ adenocarcinoma with prior progression on systemic therapy, measurable disease, ECOG PS 0-1, and baseline tumor tissue. PD-L1 was classified as positive (≥1%) or negative using the DAKO PD-L1 22C3 IHC pharmDx assay. Two dosing regimens were evaluated, Cohort A (R 8 mg/kg on Days 1&8) and Cohort B (R 10 mg/kg on Day 1), given with P 200 mg on Day 1 q3W. The primary objective was to assess safety and tolerability of adding R to P; preliminary efficacy will be examined. Results: As of 23-Jun-2016, 40 G/GEJ pts have been enrolled (Cohort A: n=23; Cohort B: n=17). First pt treated in Cohorts A and B were on 29-Feb-2016 and 26-Oct-2015, respectively. The median age was 59 y, 75% were male, 65% ...