Gastric/GEJ adenocarcinomas are aggressive tumors with a high probability of death. Current treatment guidelines include two-drug cytotoxic chemotherapy with a fluoropyrimidine (mFOLFOX6: capecitabine or fluorouracil) and a platinum-based agent (CapOx: oxaliplatin or cisplatin). In addition, the FDA has approved nivolumab, a PD-1 checkpoint inhibitor, in combination with chemotherapy as first line treatment for advanced or metastatic gastric/GEJ cancer. TST001 is a recombinant humanized monoclonal antibody against Claudin 18.2 (a tumor marker found in gastric/GEJ cancer. In this study, the combination therapy of chemotherapy or chemotherapy and pembrolizumab with and without TST001 could provide additional benefits to the management of these tumors.
1. ≥18 years of age on day of signing informed consent. 2. Histologically or cytologically confirmed diagnosis of previously untreated, unresectable locally advanced or metastatic G/GEJ adenocarcinoma.
Has received any prior systemic anticancer treatment (chemotherapy, immunotherapy, biologic therapy, or targeted therapy) for G/GEJ adenocarcinoma. Neo/adjuvant treatment is permitted as long as it was completed at least 6 months prior to randomization.
Has received prior radiotherapy within 2 weeks before randomization; Note: Subjects must have recovered from all radiation-related toxicities. A previously irradiated lesion can be used as measurable lesion as long as it progressed post radiation therapy.
Has received anti-CLDN18.2 agents at any time.
Has received any traditional Chinese medicine or proprietary Chinese medicine with anti-tumor effect within 7 days before randomization.