NCT06093425

Combination of Osemitamab (TST001), Pembrolizumab and Chemotherapy as First-line Therapy in Advanced or Metastatic GC/GEJ Adenocarcinoma

A Phase 3, Randomized, Double-blind, Placebo-controlled Study Evaluating Combination of TST001, Pembrolizumab and Chemotherapy as First-Line Treatment in Subjects With Claudin18.2 Positive Locally Advanced or Metastatic Gastric or Gastroesophageal Junction (G/GEJ) Adenocarcinoma

• Status: Not Yet Recruiting
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 820 (estimated)
• Sponsor: Suzhou Transcenta Therapeutics Co., Ltd. · Industry
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

Summary

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.

Detailed description

This Phase 3, randomized, double-blind, placebo-controlled study is designed to evaluate the safety and efficacy of TST001 in combination with pembrolizumab and chemotherapy or chemotherapy alone in subjects with tumors that express markers (HER2 negative, Claudin18.2 positive, known PD-L1 CPS status) in locally advanced or metastatic gastric/GEJ adenocarcinoma. Patients will be randomized in a 1:1 ration to receive TST001 or placebo in combination with nivolumab and chemotherapy or with chemotherapy alone.

Conditions

• Gastric Cancer
• Gastroesophageal-junction Cancer
• Advanced Cancer

Interventions

Type	Name	Description
DRUG	Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil	TST001 will be administered i.v. Q3W along with standard prescribing dose of pembrolizumab Q3W + standard prescribed regimens for FOLFOX6 or CapOx.
DRUG	Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil	Placebo will be administered i.v. Q3W along with standard prescribing dose of pembrolizumab Q3W + standard prescribed regimens for FOLFOX6 or CapOx.

Timeline

• Start date: 2026-06-30
• Primary completion: 2029-10-01
• Completion: 2030-01-31
• First posted: 2023-10-23
• Last updated: 2025-12-17

Regulatory

• FDA-regulated drug study