A Phase 3 interventional study of Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil and Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil in Gastric Cancer, Gastroesophageal-junction Cancer and Advanced Cancer, sponsored by Transcenta Therapeutics (Hangzhou) Co., Ltd.. Not yet recruiting. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-29.
Sponsored by Transcenta Therapeutics (Hangzhou) Co., Ltd. · Phase 3, Interventional, and Treatment
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.
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.
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.
3. Must be willing and able to provide archival or fresh tissue sample, a formalin-fixed, paraffin-embedded (FFPE) block, or 151 or more unstained, freshly cut, serial sections (on slides) from an FFPE tumor specimen or fresh biopsy tissue from a tumor lesion (either primary or metastatic) not previously irradiated fixed in formalin solution. FFPE tissue blocks are preferred to slides. Notes: details pertaining to tumor tissue submission can be found in the Laboratory Manual. Fresh biopsies are not required for study entry and will not be covered as part of the study procedures. Handling of the fresh biopsy tissue is an alternative offered to investigators in case they plan to biopsy the subjects as part of their standard of care; the fresh sample can be sent directly to the central laboratory if it is more convenient to the sites.
4. Positive CLDN18.2 expression in tumor tissue confirmed by the central laboratory at screening using CTA (Claudin 18.2 IHC 14G11 pharmDx).
5. Must have at least one measurable lesion or evaluable disease by CT or MRI per RECIST 1.1 criteria as assessed locally by the investigator; radiographic tumor assessment should be performed within 28 days prior to randomization.
6. Subjects should be eligible to receive chemotherapy and pembrolizumab per the investigator judgement.
7. Known PD-L1 CPS Status (tested by central laboratory to provide CPS status by PD-L1 IHC 22C3 pharmDx).
8. Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 assessed within 14 days before randomization.
9. Subjects who have AEs due to previous anticancer therapies must have recovered to ≤Grade 1 or pre-treatment status. Subjects with endocrine-related AEs who are adequately treated with hormone replacement or subjects who have ≤Grade 2 neuropathy are eligible.
10. Have a life expectancy of greater than 12 weeks. 11. Demonstrate adequate organ function.
Exclusion Criteria
TST001 + Pembrolizumab + Chemotherapy (FOLFOX6 or CapOx)
Drug: Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil
Placebo + Pembrolizumab + Chemotherapy (FOLFOX6 or CapOx)
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.
Placebo will be administered i.v. Q3W along with standard prescribing dose of pembrolizumab Q3W + standard prescribed regimens for FOLFOX6 or CapOx.
Progression free survival (PFS) based on RECIST (v1.1)
Compare PFS of patients treated with TST001 or Placebo in combination with pembrolizumab and chemotherapy
Time frame: Date of randomization until the date of documented progression or date of death due to any cause, whichever comes first up to 24 months after last dose.
Overall Survival (OS) based on RESIST
Compare OS of patients treated with TST001 or Placebo in addition to CapOx or mFOLFOX6 and pembrolizumab or CapOx or mFOLFOX6
Time frame: Time from date of randomization until the date of death due to any cause, assessed up to 24 months after last dose.
Overall Response Rate (ORR) based on RESIST (v1.1)
Compare OOR patients treated with TST001 or Placebo in addition to CapOx or mFOLFOX6 and pembrolizumab or CapOx or mFOLFOX6.
Time frame: Date of randomization up to 24 months after last dose
Quality of Life (QOL) assessed on EuroQol EQ5D-5L
Change in QOL assessments from baseline of patients treated with TST001 or Placebo in addition to mFOLFOX6 and pembrolizumab or CapOx or mFOLFOX6. Assessments include Cancer QOL questionnaires (QLC-STO22, EQ5D-5L, and QLQ-C30)
Time frame: Date of randomization until the date of documented progression, assessed up to 24 months after last dose
Disease Control Rate (DCR) based on RESIST assessed as the percentage of subjects with measurable disease
Compare DCR of patients treated with TST001 or Placebo in addition to CapOx or mFOLFOX6 and pembrolizumab or CapOx or mFOLFOX6.
Time frame: Date of randomization up to 24 months after last dose
Duration of Response (DOR) based on RESIST (log-rank test)
Compare DOR of patients treated with TST001 or Placebo in addition to CapOx or mFOLFOX6 and pembrolizumab or CapOx or mFOLFOX6.
Time frame: From date of randomization up to 24 months after last dose
Time to Response (TTR) based on RESIST
Compare TTR of patients treated with TST001 or Placebo in addition to CapOx or mFOLFOX6 and pembrolizumab or CapOx or mFOLFOX6 based on CR or PR.
Time frame: Date of randomization up to 24 months after last dose
No study locations are listed for this record.
Plan to share: No — Summary of study results will be available through Clinicaltrials.gov
No publications or documents are linked to this record.
This study is not yet recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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Transcenta Therapeutics (Hangzhou) Co., Ltd.