Interim safety and clinical activity in patients (pts) with advanced gastric or gastroesophageal junction (G/GEJ) adenocarcinoma from a multicohort phase 1 study of ramucirumab (R) plus pembrolizumab (P).

Abstract

102 Background: 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% had ECOG PS of 1, 48% were PD-L1 positive, and 70% received study treatment as third or subsequent regimen. Median duration of treatment was 2.1 mo and 4.1 mo for Cohort A and B, respectively. All grades treatment-related AEs (TRAE) occurred in 31 (78%) pts and similar between cohorts; TRAEs in ≥10% of pts were fatigue (30%), infusion related reaction (12.5%), decreased appetite (12.5%), pruritus (10%), maculopapular rash (10%), and hypertension (10%). Ten (25%) pts had grade 3-4 TRAEs, most commonly colitis (7.5%) and hypertension (7.5%). One treatment-related death occurred (pneumocystis pneumonia and pulmonary sepsis). Preliminary efficacy data showed 3 of 40 (7.5%) pts (PD-L1 negative, n=1; PD-L1 positive, n=2) have responded (1 confirmed and 2 unconfirmed PR) to treatment with a 45% disease control rate. Median PFS was 2.10 mo (95% CI, 1.18 to 4.04) and 2.60 mo (1.38, NR) for Cohorts A and B, respectively. Fifteen (37.5%) pts, including all responders, remain on treatment. Conclusions: R+P generated no new safety signals and demonstrated antitumor activity in pts with previously treated advanced G/GEJ adenocarcinoma. Clinical trial information: NCT02443324.