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NCT Number: NCT07392892

Symbiotic-GI-16: A Study to Learn About the Study Medicine Called PF-08634404 in Combination With Chemotherapy in Gastroesophageal Cancer

This study is being done to learn more about a new medicine called PF-08634404 and how well it works when given with chemotherapy to people with gastroesophageal cancer that is locally advanced (spread to nearby tissues) or has spread to other parts of the body.

To join the study, participants must meet the following conditions:

Be 18 years or older. Have locally advanced or metastatic gastric, gastroesophageal junction or esophageal adenocarcinoma Be treatment naïve for advanced or metastatic disease Be in good physical condition and have healthy organs based on medical tests.

The study has two parts:

* In the first part, researchers will check how safe the study medicine in combination with chemotherapy is and how well people respond to it. * In the second part, they will compare study medicine plus chemotherapy to another approved treatment (nivolumab plus chemotherapy) to see which works better.

The treatment will be given in repeated time periods called cycles.

Recruiting

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Key information

Conditions

Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction , or Esophageal Adenocarcinoma Adenocarcinoma Of Esophagus Digestive System Diseases Digestive System Neoplasms Esophageal Adenocarcinoma Gastroesophageal Junction Cancer Gastrointestinal Diseases Gastrointestinal Neoplasms Metastatic Gastric Cancer Neoplasms Neoplasms by Site Stomach Diseases Stomach Neoplasms

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 2 / Phase 3

Primary location

Zhongshan Hospital,Fudan University, Shanghai, Shanghai Municipality, China

Loading trial locations.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Histological or cytological confirmed gastric, gastroesophageal junction or esophageal adenocarcinoma.
  • Evidence of locally advanced or metastatic disease.
  • Eastern Cooperative Oncology Group performance status (ECOG) 0-1
  • No prior systemic therapy for advanced or metastatic disease.
  • Adequate hepatic, liver, and renal function
  • HER-2 negative status based on local testing
  • PD-L1 positive status based on local testing

Exclusion criteria

  • Participants with known active CNS metastases, including leptomeningeal, brainstem, meningeal, or spinal cord metastases or compression
  • Clinically significant risk of hemorrhage or fistula
  • Major surgery or severe trauma within 4 weeks prior to the first dose, or planned major surgery during the study
  • History of allogeneic organ transplantation and allogeneic hematopoietic stem cell transplantation.
  • Any Grade ≥3 bleeding/hemorrhage events within 28 days of Cycle 1 Day 1, or prior history of clinically significant bleeding events
  • Clinically significant cardiovascular disease, or other comorbidities, within 6 months prior to first dose
  • Participants with active autoimmune diseases requiring systemic treatment within the past 2 years
  • Evidence of non-infectious or drug-induced interstitial lung disease (ILD) pneumonitis

Treatment and study plan

PF-08634404

Biological

Participants will receive PF-08634404 intravenously.

Other names: SSGJ-707

Chemotherapy

Drug

Participants will receive PF-08634404 intravenously in combination with Chemotherapy.

Nivolumab

Biological

Participants will receive Nivolumab intravenously.

Primary outcomes

  1. Phase 2: Confirmed Objective response rate (ORR) using RECIST 1.1 as assessed by investigator

    Time frame: Approximately 4 years

    Confirmed ORR by investigator is defined as the proportion of participants with confirmed Complete Response (CR) or Partial Response (PR) per RECIST v1.1 as assessed by investigator.

  2. Phase 2: Number of participants with treatment-emergent adverse events

    Time frame: Through 90 days after the last study intervention; Approximately 4 years

    Adverse Events (AEs) as characterized by type, frequency, severity (as graded by NCI CTCAE version 5.0), timing, seriousness, and relationship to study intervention.

  3. Phase 3: Progression Free Survival (PFS) using RECIST 1.1 as assessed by BICR

    Time frame: Approximately 4 years

    PFS by BICR is defined as the time from the date of randomization to the date of first documented disease progression per RECIST 1.1 as assessed by BICR, or death due to any cause, whichever occurs first.

  4. Phase 3: Overall Survival (OS)

    Time frame: Approximately 4 years

    OS is defined as the time from the date of randomization to the date of death due to any cause.

Secondary outcomes

  1. Phase 2: Duration of Response (DOR) using RECIST 1.1 as assessed by investigator

    Time frame: Approximately 4 years

    DOR by investigator is defined as the time from the first documentation of objective response (CR or PR that is subsequently confirmed) to the date of first documented disease progression per RECIST 1.1 as assessed by investigator, respectively, or death due to any cause, whichever occurs first.

  2. Phase 2: Progression Free Survival (PFS) using RECIST 1.1 as assessed by investigator

    Time frame: Approximately 4 years

    PFS by investigator is defined as the time from the date of first dose to the date of first documented disease progression per RECIST 1.1 as assessed by investigator, or death due to any cause, whichever occurs first.

  3. Phase 2: Overall Survival (OS)

    Time frame: Approximately 4 years

    OS is defined as the time from the date of first dose to the date of death due to any cause.

  4. Phase 2: Number of participants with laboratory abnormalities

    Time frame: Through 90 days after the last study intervention; Approximately 4 years

    Laboratory abnormalities as characterized by type, frequency, severity (as graded by NCI CTCAE version 5.0), and timing. For laboratory tests without CTCAE grade definitions, results will be categorized as normal, high, low, or not done and be listed.

  5. Phase 2: Serum concentrations of PF-08634404

    Time frame: Approximately 21 months

    Predose and postdose concentrations of PF-08634404

  6. Phase 2: Incidence of Anti-Drug Antibody (ADA) against PF-08634404

    Time frame: Approximately 21 months

  7. Phase 3: ORR using RECIST 1.1 as assessed by BICR

    Time frame: Approximately 4 years

    ORR by BICR is defined as the proportion of participants with a Best Overall Response (BOR) of confirmed CR or confirmed PR per RECIST 1.1 as assessed by BICR.

  8. Phase 3: ORR using RECIST 1.1 as assessed by investigator

    Time frame: Approximately 4 years

    ORR by investigator is defined as the proportion of participants with a BOR of confirmed CR or confirmed PR per RECIST 1.1 as assessed by investigator.

  9. Phase 3: Progression free survival (PFS) using RECIST 1.1 as assessed by investigator

    Time frame: Approximately 4 years

    PFS by investigator is defined as the time from the date of randomization to the date of first documented disease progression per RECIST 1.1 as assessed by investigator, or death due to any cause, whichever occurs first

  10. Phase 3: DOR using RECIST 1.1 as assessed by BICR

    Time frame: Approximately 4 years

    DOR is defined as the time from the first documentation of objective response (CR or PR that is subsequently confirmed) to the date of first documented disease progression per RECIST 1.1 as assessed by BICR, respectively, or death due to any cause, whichever occurs first.

  11. Phase 3: DOR using RECIST 1.1 as assessed by investigator

    Time frame: Approximately 4 years

    DOR is defined as the time from the first documentation of objective response (CR or PR that is subsequently confirmed) to the date of first documented disease progression per RECIST 1.1 as assessed by investigator, respectively, or death due to any cause, whichever occurs first.

  12. Phase 3: PFS2 (PFS after next-line therapy) by investigator

    Time frame: Approximately 4 years

    PFS2 is defined as the time from the date of randomization to the date of second objective disease progression or death due to any cause, whichever occurs first

  13. Phase 3: Number of participants with treatment-emergent adverse events

    Time frame: Through 90 days after the last study intervention; Approximately 4 years

    AEs as characterized by type, frequency, intensity as graded by NCI CTCAE version 5.0, timing, seriousness, and relationship to study intervention(s)

  14. Phase 3: Number of participants with laboratory abnormalities

    Time frame: Through 90 days after the last study intervention; Approximately 4 years

    Laboratory abnormalities as characterized by type, frequency, severity (as graded by NCI CTCAE version 5.0), and timing. For laboratory tests without CTCAE grade definitions, results will be categorized as normal, high, low, or not done and be listed.

  15. Phase 3: Serum concentrations of PF-08634404

    Time frame: Approximately 21 months

    Predose and postdose concentrations of PF-08634404

  16. Phase 3: Incidence of ADA against PF-08634404

    Time frame: Approximately 21 months

  17. Phase 3: Change from baseline in Functional Assessment of Cancer Therapy - Gastric (FACT-Ga) Total score

    Time frame: Approximately 4 years

  18. Phase 3: Time to definitive deterioration in FACT-Ga Total score

    Time frame: Approximately 4 years

  19. Phase 3: Time to definitive deterioration in Gastric Cancer Subscale (GaCS) score

    Time frame: Approximately 4 years

Study contacts

Contact information is provided by the study sponsor or research team.

Pfizer CT.gov Call Center

CONTACT

[email protected]

1-800-718-1021

Sponsors and collaborators

Lead sponsor

Pfizer

Industry

Registry information

Official study title

A PHASE 2/3 INTERVENTIONAL STUDY OF PF-08634404 IN COMBINATION WITH CHEMOTHERAPY IN TREATMENT-NAÏVE PARTICIPANTS WITH LOCALLY ADVANCED OR METASTATIC GASTRIC, GASTROESOPHAGEAL JUNCTION, OR ESOPHAGEAL ADENOCARCINOMA

Important dates

Study start
2026
Primary completion
2031
Study completion
2032
First posted
Feb 6, 2026
Registry last updated
Jul 24, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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