Gastric CancerPhase 3NCT06093425

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

A Phase 3 study testing Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil in people with Gastric Cancer and Gastroesophageal-junction Cancer, run by Transcenta Therapeutics (Hangzhou) Co., Ltd..

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts

Official record

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Trial summary

Who is it for?: Ages 18 years and older
Conditions the study is for: Gastric Cancer, Gastroesophageal-junction Cancer, Advanced Cancer
What is being tested?: Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil
Type of treatment: Injection or infusion
Could I receive a placebo?: Yes, some participants may receive a placebo
How many people: 820 participants
Where: No sites listed yet
Study dates: 30 Jun 2027to 31 Jan 2030
Phase: Phase 3
Are there results?: Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 years and older
All sexes
No healthy volunteers
Adult, Older adult

Who may be able to join

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).

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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.

Who cannot join

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.
Has received vaccines (live, attenuated, or research vaccines) within 30 days before randomization. Administration of killed vaccines is allowed.

Trial locations and contacts

No sites are listed yet. Contact the study team or a site near you to ask about taking part.

C Qi, MD contact

+86 57128279502

charlie.qi@transcenta.com

About this study

Official title: 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

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.

Read the 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
Being tested: Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil
Medical subject headings: Stomach Neoplasms

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

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

Study groups in NCT06093425
Study group	Role	What they receive
TST001 + PDL-1 + Chemotherapy	Active comparator	TST001 + Pembrolizumab + Chemotherapy (FOLFOX6 or CapOx) Receives: Drug: Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil
Placebo	Placebo comparator	Placebo + Pembrolizumab + Chemotherapy (FOLFOX6 or CapOx) Receives: Drug: Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil

What is being measured

The primary outcome is the main question the study is designed to answer.

Progression free survival (PFS) based on RECIST (v1.1)
Compare PFS of patients treated with TST001 or Placebo in combination with pembrolizumab and chemotherapy
Measured: 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.

Secondary outcomes (6)

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
Measured: 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.
Measured: 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)
Measured: 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.
Measured: 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.
Measured: 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.
Measured: Date of randomization up to 24 months after last dose

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

30 Jun 202731 Jan 2030

First posted23 Oct 2023
Study start30 Jun 2027 (estimated)
Primary completion1 Oct 2029 (estimated)
Study completion31 Jan 2030 (estimated)

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Other trials for Gastric CancerStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 3
Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Model description: Randomized, Double-Blind, Placebo-Controlled
Masking: Triple blind
Who is masked: Participant, Investigator, Outcomes assessor
Enrolment: 820 participants (estimated)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06093425
Sponsor's protocol ID: TST001-3001
Status last verified: Sep 2026
First submitted: 24 Sep 2023
Last updated: 29 Sep 2026
Results posted: No
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: No: Summary of study results will be available through Clinicaltrials.gov

Study at a glance

From the registry record, last updated by the sponsor on 29 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: 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
ClinicalTrials.gov ID: NCT06093425
Acronym / sponsor ID: TST001-3001
Conditions: Gastric Cancer, Gastroesophageal-junction Cancer, Advanced Cancer
Phase: Phase 3
Study type: Interventional
Recruitment status: Not yet recruiting
Enrolment: 820 participants (estimated)
Lead sponsor: Transcenta Therapeutics (Hangzhou) Co., Ltd.Industry (pharma, biotech, devices)
Study start: 30 Jun 2027 (estimated)
Primary completion: 1 Oct 2029 (estimated)
Study completion: 31 Jan 2030 (estimated)
First posted: 23 Oct 2023 (actual)
Results: Not posted in the source record

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Detailed description

Study design

Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Masking: Triple blind (participant, investigator, outcomes assessor)
Number of arms: 2
Model description: Randomized, Double-Blind, Placebo-Controlled

Arm	Type	Receives
TST001 + PDL-1 + Chemotherapy	Active comparator	Drug: Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracilTST001 + Pembrolizumab + Chemotherapy (FOLFOX6 or CapOx)
Placebo	Placebo comparator	Drug: Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracilPlacebo + Pembrolizumab + Chemotherapy (FOLFOX6 or CapOx)

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Adult, Older adult

Key inclusion criteria (9 listed)

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.

Key exclusion criteria (5 listed)

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.
Has received vaccines (live, attenuated, or research vaccines) within 30 days before randomization. Administration of killed vaccines is allowed.

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracilTST001 will be administered i.v. Q3W along with standard prescribing dose of pembrolizumab Q3W + standard prescribed regimens for FOLFOX6 or CapOx.	Drug	Placebo
Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracilPlacebo will be administered i.v. Q3W along with standard prescribing dose of pembrolizumab Q3W + standard prescribed regimens for FOLFOX6 or CapOx.	Drug	TST001 + PDL-1 + Chemotherapy

Primary outcome

Progression free survival (PFS) based on RECIST (v1.1)
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.
Compare PFS of patients treated with TST001 or Placebo in combination with pembrolizumab and chemotherapy

6 secondary outcomes

Overall Survival (OS) based on RESIST
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)
Time frame: Date of randomization up to 24 months after last dose
Quality of Life (QOL) assessed on EuroQol EQ5D-5L
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
Time frame: Date of randomization up to 24 months after last dose
Duration of Response (DOR) based on RESIST (log-rank test)
Time frame: From date of randomization up to 24 months after last dose
Time to Response (TTR) based on RESIST
Time frame: Date of randomization up to 24 months after last dose

Results and safety

This study is still under way. Results are not available in the source record yet.

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 29 Sep 2026.
Individual participant dataSharing planned: No. Summary of study results will be available through Clinicaltrials.gov

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.

C Qi, MD contact

+86 57128279502

charlie.qi@transcenta.com

Questions about this trial

What is this clinical trial studying?

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 9 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: opening soon, as of the sponsor's last update on 29 Sep 2026. Status can change between updates, so confirm with the study contact before making plans.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact C Qi, MD (+86 57128279502, charlie.qi@transcenta.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Progression free survival (PFS) based on RECIST (v1.1) (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.). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06093425.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Sep 2026.