A phase 3 randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of GS-5745 combined with mFOLFOX6 as first-line treatment in patients with advanced gastric or gastroesophageal junction adenocarcinoma.

Abstract

TPS217 Background: GS-5745 is a monoclonal antibody that inhibits matrix metalloproteinase 9 (MMP9), an extracellular enzyme involved in matrix remodeling, tumor growth, and metastasis. Inhibiting MMP9 is expected to block paracrine signaling and metastasis and to alter the immune microenvironment within the tumor. GS-5745 (800 mg every 2 weeks) with mFOLFOX6 was examined in a Phase 1b study in 40 patients with gastric and GEJ adenocarcinoma (GS-US-296-0101), and demonstrated encouraging activity without added toxicity. Additionally, decreased serum biomarkers suggested inhibition of MMP9 enzymatic activity by these agents. These data support the hypothesis that GS-5745 treatment inhibits MMP9 activity and that the inhibition may lead to improved clinical outcomes. Methods: This phase 3, randomized, double-blind, multicenter study investigates the efficacy and safety of GS-5745 combined with mFOLFOX6 in subjects with untreated gastric and GEJ adenocarcinoma. Total of 430 eligible subjects with advanced gastric and GEJ cancer will be randomized in a 1:1 manner to mFOLFOX6 plus GS-5745 or mFOLFOX6 plus placebo. Stratification factors include ECOG status (0 v 1), geographic region (Latin America v All other countries), and primary tumor site (gastric v GEJ). CT or MRI scans will be performed every 8 weeks to evaluate response to treatment. mFOLFOX6 will be administered on Days 1 and 15 of each 28-day treatment cycle for a total of 6 cycles followed thereafter by leucovorin (LV) and 5-fluorouracil (5-FU) dosing on Days 1 and 15 of each 28-day treatment cycle until disease progression. GS-5745/placebo 800 mg will be infused on Days 1 and Day 15 of each 28 day cycle until disease progression. Primary endpoint is OS, and secondary endpoints include PFS, ORR (RECIST 1.1), and safety. The study is designed to have an 85% power to detect clinically meaningful improvement in overall survival at the one-sided significance level of 0.025. The association of exploratory biomarkers with study drug response will also be evaluated. Enrollment opened Oct. 2015. Clinical trial information: NCT02545504.