A Study of Zolbetuximab (IMAB362) in Adults With Gastric Cancer

This is a study to assess the antitumor activity of zolbetuximab, an Immunoglobulin (IgG1) chimeric monoclonal antibody directed against CLDN18.2, in subjects with recurrent locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma and locoregional gastric or GEJ adenocarcinoma whose tumors are CLDN18.2 positive. For each cohort, the study consists of the following periods: pre-screening; screening; treatment; and follow-up for disease progression (or post-treatment follow-up for disease recurrence, which will be conducted for Cohort 5). In addition, there will be a survival follow-up period for Cohorts 1A, 4B, and 5 participants only. Tolerability of zolbetuximab in combination with pembrolizumab in Japanese participant(s) will be evaluated in Cohort 3A DLT assessment. Tolerability of zolbetuximab in combination with mFOLFOX6 and nivolumab in Japanese subject(s) will be evaluated in Cohort 4B, if Japanese subjects are not enrolled in the Cohort 4A DLT assessment.