614O - Final results of the FAST study, an international, multicenter, randomized, phase II trial of epirubicin, oxaliplatin, and capecitabine (EOX) with or without the anti-CLDN18.2 antibody IMAB362 as first-line therapy in patients with advanced CLDN18.2+ gastric and gastroesophageal junction (GEJ) adenocarcinoma

Abstract

Background: IMAB362, a chimeric monoclonal antibody that mediates specific killing of cancer cells expressing the tight junction protein Claudin18.2 (CLDN18.2) by activation of immune effector mechanisms, has demonstrated single-agent activity and tolerability in patients ( pts) with heavily pretreated gastric cancer. Methods: Pts with advanced/recurrent gastric and GEJ cancer were centrally evaluated for CLDN18.2 expression by immunohistochemistry (CLAUDETECT® 18.2 Histology Kit). Eligible pts had a CLDN18.2 expression of ≥2+ in ≥40% tumor cells, an ECOG PS of 0–1 and were not eligible for trastuzumab. Pts were randomized 1:1 to first-line EOX (epirubicin 50 mg/m2 and oxaliplatin 130 mg/m2 d1, and capecitabine 625 mg/m2 bid, d1–21; qd22) with or without IMAB362 (loading dose 800 mg/m2, then 600 mg/m2 d1, qd21). An exploratory arm (N = 85) was added to investigate a higher dose IMAB362 (1000 mg/m2) plus EOX. The primary study endpoint was PFS (Arm1 vs 2,70% power, hazard ratio [HR] 0.72, 1-sided p = 0.1). Here we present the final study results.