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

Zolbetuximab is being studied as a treatment for people with cancer in and around the stomach or cancer where the food pipe (esophagus) joins the stomach (gastroesophageal junction cancer). Most people with this type of cancer have a protein called Claudin 18.2 in their tumor. Zolbetuximab is thought to work by attaching to Claudin 18.2 in their tumor. This switches on the body's immune system to attack the tumor. There is an unmet medical need to treat people with advanced cancer in and around the stomach or gastroesophageal junction cancer. This study will provide more information on zolbetuximab given by itself and in combination with other treatments in adults with advanced stomach or gastroesophageal junction cancer. The study is currently ongoing globally. People in this study will either be treated with zolbetuximab by itself, with zolbetuximab and chemotherapy, with zolbetuximab and a medicine called pembrolizumab, or zolbetuximab with chemotherapy and a medicine called nivolumab. This study is ongoing, but enrollment in any of the treatment options has been completed. In addition, at this stage of the study, treatment in some of these treatment options has completed. The main aim of this study is to check how well zolbetuximab controls tumors when given by itself. Adults with cancer in and around the stomach or gastroesophageal junction cancer can take part. Their cancer is locally advanced unresectable or metastatic and has the CLDN18.2 marker in a tumor sample. Locally advanced means the cancer has spread to nearby tissue. Unresectable means the cancer cannot be removed by surgery. Metastatic means the cancer has spread to other parts of the body. They may have been previously treated with standard therapies. People cannot take part if they need to take medicines to suppress their immune system, have blockages or bleeding in their gut, have specific uncontrollable cancers such as symptomatic or untreated cancers in the nervous system, have a specific heart condition or infections. There are different treatments in the study. People who take part will receive just 1 of the treatments. Treatment will be given in cycles. The treatment is given through a vein; this is called an infusion. Some people with advanced disease will have 1 infusion in 3 week (21-day) cycles. Some people will have several infusions in 6 week (42-day) cycles. Some people with cancer in and around the stomach or gastroesophageal junction who have surgery for their cancer will have a few infusions in 2-week (14-day) cycles. This will happen before and after they have surgery for their cancer. People may receive chemotherapy for up to 6 months. Some people enrolled to received zolbetuximab and pembrolizumab, may have received pembrolizumab for up to 2 years. People will visit the clinic on certain days during their treatment; there may be extra visits during the first cycle of treatment. The study doctors will check if people had any medical problems from zolbetuximab and the other study treatments. Also, people in the study will have a health check including blood tests. On some visits they will also have scans to check for any changes in their cancer. Tumor samples will be taken at certain visits with the option of giving a tumor sample after treatment has finished. People will visit the clinic after they stop treatment. They will be asked about any medical problems and will have a health check including blood tests. After the clinic visits end some people will have a telephone health check every 3 months. The number of visits and checks done at each visit will depend on the health of each person and whether they completed their treatment or not.

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.