LBA-06 IMAB362: a novel immunotherapeutic antibody targeting the tight-junction protein component CLAUDIN18.2 in gastric cancer

Abstract

Background: Claudin18.2 (CLDN18.2) is a tight junction protein expressed by several cancers including gastric and GEJ adenocarcinoma. IMAB362 is a chimeric monoclonal antibody that mediates specific killing of CLDN18.2-positive cancer cells by activation of immune effector mechanisms. Methods: Patients (pts) with advanced/recurrent gastric and GEJ cancer were centrally evaluated for CLDN18.2 expression by IHC (validated CLAUDETECT18.2 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). The study was extended by an exploratory Arm3 (N=85) to investigate a high dose IMAB362 (1000 mg/m2) plus EOX, (not subject here). The primary study endpoint was PFS. Results: 730 pts were consented, of whom 352 pts (48%) were tested CLDN18.2+ per protocol criteria. Of those, 161 pts (median age, 58 yrs; male 64%; gastric, 80%; GEJ, 16%; esophageal, 4%) were randomized into Arms1 and 2. IMAB362 plus EOX improved PFS (mPFS 4.8 v 7.9 mon; HR 0.47; p