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Not yet recruitingNCT06093425Updated Sep 29, 2026

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

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

Updated Sep 29, 2026Start date movedSponsor changedGo to Updates ↓

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Phase
Phase 3
Study type
Interventional
Enrollment
820
Allocation
Randomized
Ages
18 Years and older
Sex
All
01

Study 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.

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.

02

Conditions studied

  • Gastric Cancer
  • Gastroesophageal-junction Cancer
  • Advanced Cancer

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03

In context

Stomach Neoplasms

3,401 studies on the registry are indexed under Stomach Neoplasms; 993 are open to participants now.

This study's planned enrollment of 820 is above the median of 66 across 2,500 interventional studies indexed under Stomach Neoplasms.

Browse Stomach Neoplasms studies →

Lead sponsor

Transcenta Therapeutics (Hangzhou) Co., Ltd. is the lead sponsor of 5 studies on the registry; 2 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
All
Accepts healthy volunteers
No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  • 1. ≥18 years of age on day of signing . 2. or cytologically confirmed diagnosis of previously untreated, unresectable locally advanced or 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 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 or evaluable disease by CT or MRI per 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 CPS Status (tested by central laboratory to provide CPS status by PD-L1 IHC 22C3 pharmDx).

    8. Have an (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 of greater than 12 weeks. 11. Demonstrate adequate organ function.

Exclusion criteria

Exclusion Criteria

  1. Has received any prior systemic anticancer treatment (chemotherapy, immunotherapy, biologic therapy, or targeted therapy) for G/GEJ adenocarcinoma. Neo/ treatment is permitted as long as it was completed at least 6 months prior to randomization.
  2. 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 as long as it progressed post radiation therapy.
  3. Has received anti-CLDN18.2 agents at any time.
  4. Has received any traditional Chinese medicine or proprietary Chinese medicine with anti-tumor effect within 7 days before randomization.
  5. Has received vaccines (live, attenuated, or research vaccines) within 30 days before randomization. Administration of killed vaccines is allowed.
Terms in these criteria, in plain language(10)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

Histologically or cytologically confirmed

The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).

Your pathology report is the document that shows this.

Metastases

Cancer that has spread from where it began to other parts of the body. “Metastatic” cancer is cancer that has spread this way.

Biopsy and archival tissue

A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.

Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.

Measurable disease

The amount of disease can be tracked with a defined measurement, so the study can see whether it shrinks or grows. It might be a tumour measured on a scan or, in some blood cancers such as myeloma, a marker measured in blood or urine.

The criteria or the study team say which measurement counts — having no tumour visible on a scan does not by itself rule you out.

RECIST

The standard rules for measuring tumours on CT or MRI scans, to tell whether a cancer is shrinking, stable or growing during treatment.

“Measurable disease per RECIST 1.1” usually means at least one tumour 10 mm or more at its longest on a CT scan, or a lymph node 15 mm or more across its short axis.

PD-1, PD-L1 and checkpoint inhibitors

PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.

PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.

ECOG performance status

A scale of how much an illness limits everyday activity. For people being assessed to join a study, scores run from 0 (fully active) to 4; lower is more active.

0
Fully active, no restrictions.
1
Limited in strenuous activity, but walking and able to do light work, such as housework or office work.
2
Walking and able to look after yourself, but unable to work; up and about more than half of waking hours.
3
Able to look after yourself only in part; in bed or a chair more than half of waking hours.
4
Unable to look after yourself at all; in bed or a chair all day.

Studies most often ask for 0–1 or 0–2. Your doctor gives the score; the WHO scale uses the same steps. The full scale also has 5, which records death.

Life expectancy

The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.

Adjuvant and neoadjuvant

Neoadjuvant treatment is given before the main treatment (usually surgery), often to shrink a tumour. Adjuvant treatment is given after it, to lower the chance of the cancer coming back.

05

Study design

Phase
Phase 3
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Triple (Participant, Investigator, Outcomes assessor)
Enrollment
820 participants (estimated)

Study arms

  • Active comparator
    TST001 + PDL-1 + Chemotherapy

    TST001 + Pembrolizumab + Chemotherapy (FOLFOX6 or CapOx)

    Drug: Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil

  • Placebo comparator
    Placebo

    Placebo + Pembrolizumab + Chemotherapy (FOLFOX6 or CapOx)

    Drug: Pembrolizumab and either Capcecitabine + Oxaliplatin or Oxaliplatin+Leucovorin + 5-fluorouracil

Interventions

  • DrugPembrolizumab 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.

  • DrugPembrolizumab 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.

This study also gives Pembrolizumab. No intervention listed here names it: that was found by reading the record.

06

What researchers measure

Primary outcomes

  1. 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.

Secondary outcomes

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

07

Study locations

No study locations are listed for this record.

08

References and documents

Individual participant data

Plan to share: No — Summary of study results will be available through Clinicaltrials.gov

No publications or documents are linked to this record.

09

Timeline

1 registry update since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reachedDate before it movedWhere the date was before it movedSimilar studies: half by the dot; the band is the middle halfHalf of similar studies reached it by the dot; the band is the middle half, from a quarter to three quarters

Start is estimated for Jun 2027; primary completion for Oct 2029, 27 months later.

Of 45 industry-sponsored phase 3 interventional studies under Stomach Neoplasms, half reached primary completion within 45 months of starting (the median), counting those still running; a quarter within 32 and three quarters within 55. This study's planned 27 months is below that.

Counting every sponsor, half of 118 studies reached it within 52 months; a quarter within 39 and three quarters within 96.

Start moved once since we started tracking on Sep 25, 2026: Jun 2026 → Jun 2027, on Sep 29, 2026.

Earlier changes are on the record history on ClinicalTrials.gov ↗

How these figures are worked out, and which studies are left out of them.

Registered
Sep 24, 2023
First posted
Oct 23, 2023
StartEst.
Jun 30, 2027was Jun 2026
Primary completionEst.
Oct 1, 2029
CompletionEst.
Jan 31, 2030
Last update
Sep 29, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
Start date
Jun 30, 2026→Jun 30, 2027
Sep 29, 2026
Sponsor
Suzhou Transcenta Therapeutics Co., Ltd.→Transcenta Therapeutics (Hangzhou) Co., Ltd.
Sep 29, 2026
Show all 1 update
  1. Sep 29, 2026
    Start date Jun 30, 2026→Jun 30, 2027
    Sponsor Suzhou Transcenta Therapeutics Co., Ltd.→Transcenta Therapeutics (Hangzhou) Co., Ltd.
    + 2 other changes: identifiers and verification date

From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗

10

Registry details

Key details

Study ID
NCT06093425
Lead sponsor
Transcenta Therapeutics (Hangzhou) Co., Ltd.
Responsible party
Sponsor
First posted
Oct 23, 2023
Start date
Jun 30, 2027 (estimated)
Primary completion
Oct 1, 2029 (estimated)
Completion
Jan 31, 2030 (estimated)
Last update
Sep 29, 2026

Study contacts

C Qi, MD
Contact
charlie.qi@transcenta.com
+86 57128279502

Oversight

FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

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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