Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction , or Esophageal AdenocarcinomaPhase 2/3NCT07392892
Symbiotic-GI-16: A Study to Learn About the Study Medicine Called PF-08634404 in Combination With Chemotherapy in Gastroesophageal Cancer
A Phase 2/3 study testing PF-08634404, Chemotherapy and Nivolumab in people with Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction , or Esophageal Adenocarcinoma and Metastatic Gastric Cancer, run by Pfizer at 102 sites in 10 countries.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction , or Esophageal Adenocarcinoma, Metastatic Gastric Cancer, Gastroesophageal Junction Cancer
- What is being tested?
- PF-08634404, Chemotherapy and Nivolumab
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 840 participants
- Where
- 102 sitesin 10 countries
- Study dates
- 14 May 2026to 21 Jul 2032
- Phase
- Phase 2/3
- 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
- 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
Who cannot join
- 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
Trial locations and contacts
102 sites in 10 countries. Contact the study team or a site near you to ask about taking part.
102 sites in 10 countries
United States83 sites, 83 recruiting
- Recruiting
Maryland Oncology Hematology, P.A.
Annapolis, Maryland, 21401
- Recruiting
Virginia Cancer Specialists, PC
Arlington, Virginia, 22201
- Recruiting
Illinois Cancer Specialists
Arlington Heights, Illinois, 60005
- Recruiting
UCLA Hematology/Oncology - Atascadero
Atascadero, California, 93422
- Recruiting
Rocky Mountain Cancer Centers, LLP
Aurora, Colorado, 80012
- Recruiting
Alliance Cancer Specialists, PC
Bensalem, Pennsylvania, 19020
- Recruiting
Maryland Oncology Hematology, P.A.
Bethesda, Maryland, 20817
- Recruiting
Illinois CancerCare - Bloomington
Bloomington, Illinois, 61704
- Recruiting
Rocky Mountain Cancer Centers, LLP
Boulder, Colorado, 80303
- Recruiting
Maryland Oncology Hematology, P.A.
Brandywine, Maryland, 20613
- Recruiting
UCLA Hematology/Oncology - Burbank
Burbank, California, 91505
- Recruiting
Rocky Mountain Cancer Centers, LLP
Centennial, Colorado, 80112
- Recruiting
Virginia Oncology Associates
Chesapeake, Virginia, 23320
- Recruiting
Illinois Cancer Specialists
Chicago, Illinois, 60631
- Recruiting
Oncology Hematology Care Clinical Trials, LLC
Cincinnati, Ohio, 45211
- Recruiting
Oncology Hematology Care Clinical Trials, LLC
Cincinnati, Ohio, 45242
- Recruiting
Oncology Hematology Care Clinical Trials, LLC
Cincinnati, Ohio, 45245
- Recruiting
Rocky Mountain Cancer Centers, LLP
Colorado Springs, Colorado, 80907
- Recruiting
Rocky Mountain Cancer Centers, LLP
Colorado Springs, Colorado, 80923
- Recruiting
Maryland Oncology Hematology, P.A.
Columbia, Maryland, 21044
- Not yet recruiting
Florida Cancer Specialists
Daytona Beach, Florida, 32117
- Recruiting
Rocky Mountain Cancer Centers, LLP
Denver, Colorado, 80218
- Recruiting
Rocky Mountain Cancer Centers, LLP
Denver, Colorado, 80220
- Recruiting
Alliance Cancer Specialists, PC
Doylestown, Pennsylvania, 18901
- Recruiting
UCLA Hematology/Oncology - Encino
Encino, California, 91436
- Recruiting
Rocky Mountain Cancer Centers, LLP
Englewood, Colorado, 80113
- Recruiting
Virginia Cancer Specialists, PC
Fairfax, Virginia, 22031
- Recruiting
Oncology Hematology Care Clinical Trials, LLC
Fairfield, Ohio, 45014
- Not yet recruiting
Florida Cancer Specialists
Fleming Island, Florida, 32003
- Recruiting
Illinois CancerCare - Galesburg
Galesburg, Illinois, 61401
- Recruiting
Maryland Oncology Hematology, P.A.
Germantown, Maryland, 20876
- Recruiting
Virginia Oncology Associates
Hampton, Virginia, 23666
- Recruiting
Alliance Cancer Specialists, PC
Horsham, Pennsylvania, 19044
- Recruiting
US Oncology Investigational Products Center (IPC)
Irving, Texas, 75063
- Recruiting
Rocky Mountain Cancer Centers, LLP
Lakewood, Colorado, 80228
- Recruiting
Alliance Cancer Specialists, PC
Langhorne, Pennsylvania, 19047
- Recruiting
Maryland Oncology Hematology, P.A.
Largo, Maryland, 20774
- Recruiting
Rocky Mountain Cancer Centers, LLP
Littleton, Colorado, 80120
- Recruiting
Rocky Mountain Cancer Centers, LLP
Lone Tree, Colorado, 80124
- Recruiting
Memorial Sloan Kettering Cancer Center Pharmacy (IMP ship to address)
Long Island City, New York, 11101
- Recruiting
Memorial Sloan Kettering Cancer Center Pharmacy (IMP storage location)
Long Island City, New York, 11101
- Recruiting
Rocky Mountain Cancer Centers, LLP
Longmont, Colorado, 80504
- Recruiting
Virginia Cancer Specialists, PC
Manassas, Virginia, 20110
- Recruiting
UCLA Hematology/Oncology - Marina del Rey
Marina del Rey, California, 90292
- Recruiting
Alliance Cancer Specialists, PC
Media, Pennsylvania, 19063
- Not yet recruiting
Atlantic Health System
Morristown, New Jersey, 07960
- Recruiting
Memorial Sloan Kettering Cancer Center - David H. Koch Center for Cancer Care (74th Street).
New York, New York, 10021
- Recruiting
Rockefeller Outpatient Pavilion (53rd Street)
New York, New York, 10022
- Recruiting
Memorial Sloan Kettering Cancer Center - Main Campus
New York, New York, 10065
- Recruiting
Virginia Oncology Associates
Newport News, Virginia, 23606
- Recruiting
Illinois Cancer Specialists
Niles, Illinois, 60714
- Recruiting
Virginia Oncology Associates
Norfolk, Virginia, 23502
- Recruiting
Illinois CancerCare-Ottawa-Fox River Cancer Center
Ottawa, Illinois, 61350
- Not yet recruiting
Florida Cancer Specialists
Palm Beach Gardens, Florida, 33410
- Recruiting
Illinois CancerCare-Pekin
Pekin, Illinois, 61554
- Recruiting
Illinois CancerCare, P.C.
Peoria, Illinois, 61615
- Recruiting
Illinois CancerCare-Peru - Valley Regional Cancer Center
Peru, Illinois, 61354
- Recruiting
UCLA Hematology/Oncology - Porter Ranch
Porter Ranch, California, 91326
- Recruiting
Rocky Mountain Cancer Centers, LLP
Pueblo, Colorado, 81003
- Recruiting
Renown Health Medical Oncology
Reno, Nevada, 89502
- Recruiting
Renown Office of Clinical Research
Reno, Nevada, 89502
- Recruiting
Renown Regional Medical Center
Reno, Nevada, 89502
- Recruiting
Virginia Cancer Specialists, PC
Reston, Virginia, 20190
- Recruiting
Maryland Oncology Hematology, P.A.
Rockville, Maryland, 20850
- Not yet recruiting
UCSF Helen Diller Family Comprehensive Cancer Center
San Francisco, California, 94158
- Not yet recruiting
UCSF Investigational Drugs Pharmacy
San Francisco, California, 94158
- Recruiting
UCLA Hematology/Oncology - San Luis Obispo
San Luis Obispo, California, 93401
- Recruiting
UCLA Hematology/Oncology - Santa Barbara
Santa Barbara, California, 93101
- Recruiting
UCLA Hematology/Oncology - Santa Monica
Santa Monica, California, 90404
- Recruiting
Harborview Medical Center
Seattle, Washington, 98104
- Recruiting
Fred Hutchinson Cancer Center
Seattle, Washington, 98109
- Recruiting
University of Washington Medical Center
Seattle, Washington, 98195
- Not yet recruiting
Florida Cancer Specialists
Sebring, Florida, 33870
- Recruiting
Alliance Cancer Specialists, PC
Sellersville, Pennsylvania, 18960
- Recruiting
Maryland Oncology Hematology, P.A.
Silver Spring, Maryland, 20904
- Not yet recruiting
Atlantic Health System / Overlook Medical Center
Summit, New Jersey, 07901
- Recruiting
Rocky Mountain Cancer Centers, LLP
Thornton, Colorado, 80260
- Recruiting
Virginia Oncology Associates
Virginia Beach, Virginia, 23456
- Recruiting
Illinois CancerCare-Washington
Washington, Illinois, 61571
- Not yet recruiting
Florida Cancer Specialists
Wellington, Florida, 33414
- Not yet recruiting
Florida Cancer Specialists
West Palm Beach, Florida, 33401
- Recruiting
Virginia Cancer Specialists, PC
Woodbridge, Virginia, 22191
- Recruiting
Alliance Cancer Specialists, PC
Wynnewood, Pennsylvania, 19096
China4 sites, 4 recruiting
- Recruiting
Sichuan Cancer hospital
Chengdu, Sichuan, 610041
- Recruiting
The Sixth Affiliated hospital, Sun Yat-sen University
Guangzhou, Guangdong, 510655
- Recruiting
Zhongshan Hospital,Fudan University
Shanghai, Shanghai Municipality, 200031
- Recruiting
Hubei Cancer Hospital
Wuhan, Hubei, 430079
Israel3 sites, 3 recruiting
- Recruiting
Rabin Medical Center
Petah Tikva, Central District, 4941492
- Recruiting
Sheba Medical Center
Ramat Gan, HA Merkaz, 5265601
- Recruiting
Sourasky Medical Center
Tel Aviv, TELL ABĪB, 6423906
Spain3 sites, 3 recruiting
- Recruiting
Hospital Universitari Vall d'Hebron
Barcelona, Barcelona [barcelona], 08035
- Recruiting
Hospital Universitario 12 de Octubre
Madrid, Madrid, Comunidad de, 28041
- Not yet recruiting
Complexo Hospitalario Universitario de Ourense
Ourense, Ourense [orense], 32005
Taiwan3 sites, 3 recruiting
- Recruiting
National Cheng Kung University Hospital
Tainan, 704302
- Recruiting
National Taiwan University Hospital
Taipei, 10002
- Recruiting
Taipei Veterans General Hospital
Taipei, 11217
Puerto Rico2 sites, 2 recruiting
- Recruiting
Pan American Center for Oncology Trials, LLC - Bayamón Office
Bayamón, 00959
- Recruiting
Pan American Center for Oncology Trials, LLC - Manati Office
Manati, United States, 00674
Canada1 site, 1 recruiting
- Not yet recruiting
London Health Sciences Centre - Verspeeten Family Cancer Centre
London, Ontario, N6A 5W9
France1 site, 1 recruiting
- Recruiting
Hôpital Européen Georges Pompidou
Paris, 75015
Italy1 site, 1 recruiting
- Recruiting
Istituto Europeo di Oncologia IRCCS
Milan, 20141
Japan1 site, 1 recruiting
- Recruiting
Aichi Cancer Center
Nagoya, Aichi-ken, 464-8681
About this study
Official 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
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:
Read more
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.
- Conditions
- Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction , or Esophageal Adenocarcinoma, Metastatic Gastric Cancer, Gastroesophageal Junction Cancer, Esophageal Adenocarcinoma
- Being tested
- PF-08634404, Chemotherapy, Nivolumab
- Keywords
- gastric cancer, gastroesophageal junction cancer, esophageal adenocarcinoma
- Medical subject headings
- Stomach Neoplasms, Adenocarcinoma Of Esophagus
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
PF-08634404Biological
Also called SSGJ-707
Participants will receive PF-08634404 intravenously.
ChemotherapyDrug
Participants will receive PF-08634404 intravenously in combination with Chemotherapy.
NivolumabBiological
Participants will receive Nivolumab intravenously.
| Study group | Role | What they receive |
|---|---|---|
| Phase 2 Portion | Experimental | PF-08634404 + Chemotherapy Receives: Biological: PF-08634404; Drug: Chemotherapy |
| Phase 3: Arm A | Experimental | PF-08634404 + Chemotherapy Receives: Biological: PF-08634404; Drug: Chemotherapy |
| Phase 3: Arm B | Active comparator | Nivolumab + Chemotherapy Receives: Drug: Chemotherapy; Biological: Nivolumab |
What is being measured
The primary outcome is the main question the study is designed to answer.
Phase 2: Confirmed Objective response rate (ORR) using RECIST 1.1 as assessed by investigator
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.
Measured: Approximately 4 years
Phase 2: Number of participants with treatment-emergent adverse events
Adverse Events (AEs) as characterized by type, frequency, severity (as graded by NCI CTCAE version 5.0), timing, seriousness, and relationship to study intervention.
Measured: Through 90 days after the last study intervention; Approximately 4 years
Phase 3: Progression Free Survival (PFS) using RECIST 1.1 as assessed by BICR
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.
Measured: Approximately 4 years
Phase 3: Overall Survival (OS)
OS is defined as the time from the date of randomization to the date of death due to any cause.
Measured: Approximately 4 years
Secondary outcomes (19)
Phase 2: Duration of Response (DOR) using RECIST 1.1 as assessed by investigator
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.
Measured: Approximately 4 years
Phase 2: Progression Free Survival (PFS) using RECIST 1.1 as assessed by investigator
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.
Measured: Approximately 4 years
Phase 2: Overall Survival (OS)
OS is defined as the time from the date of first dose to the date of death due to any cause.
Measured: Approximately 4 years
Phase 2: Number of participants with laboratory abnormalities
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.
Measured: Through 90 days after the last study intervention; Approximately 4 years
Phase 2: Serum concentrations of PF-08634404
Predose and postdose concentrations of PF-08634404
Measured: Approximately 21 months
Phase 2: Incidence of Anti-Drug Antibody (ADA) against PF-08634404
Measured: Approximately 21 months
Phase 3: ORR using RECIST 1.1 as assessed by BICR
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.
Measured: Approximately 4 years
Phase 3: ORR using RECIST 1.1 as assessed by investigator
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.
Measured: Approximately 4 years
Phase 3: Progression free survival (PFS) using RECIST 1.1 as assessed by investigator
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
Measured: Approximately 4 years
Phase 3: DOR using RECIST 1.1 as assessed by BICR
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.
Measured: Approximately 4 years
Phase 3: DOR using RECIST 1.1 as assessed by investigator
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.
Measured: Approximately 4 years
Phase 3: PFS2 (PFS after next-line therapy) by investigator
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
Measured: Approximately 4 years
Phase 3: Number of participants with treatment-emergent adverse events
AEs as characterized by type, frequency, intensity as graded by NCI CTCAE version 5.0, timing, seriousness, and relationship to study intervention(s)
Measured: Through 90 days after the last study intervention; Approximately 4 years
Phase 3: Number of participants with laboratory abnormalities
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.
Measured: Through 90 days after the last study intervention; Approximately 4 years
Phase 3: Serum concentrations of PF-08634404
Predose and postdose concentrations of PF-08634404
Measured: Approximately 21 months
Phase 3: Incidence of ADA against PF-08634404
Measured: Approximately 21 months
Phase 3: Change from baseline in Functional Assessment of Cancer Therapy - Gastric (FACT-Ga) Total score
Measured: Approximately 4 years
Phase 3: Time to definitive deterioration in FACT-Ga Total score
Measured: Approximately 4 years
Phase 3: Time to definitive deterioration in Gastric Cancer Subscale (GaCS) score
Measured: Approximately 4 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted6 Feb 2026
- Study start14 May 2026
- Primary completion22 Jul 2031 (estimated)
- Study completion21 Jul 2032 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction , or Esophageal AdenocarcinomaStudies of the same condition, open and under way.
- More trials run by PfizerThe sponsor's other registered studies.
- 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 2/3
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 840 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Pfizer
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
- Investigators
- Pfizer CT.gov Call Center, Study director, Pfizer
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07392892
- Sponsor's protocol ID
- C6461016
- Other IDs
- 2025-524717-86-00, 2025
- Status last verified
- Oct 2026
- First submitted
- 30 Jan 2026
- Last updated
- 13 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.
Study at a glance
From the registry record, last updated by the sponsor on 13 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official 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
- ClinicalTrials.gov ID
- NCT07392892
- Acronym / sponsor ID
- C6461016
- Conditions
- Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction , or Esophageal Adenocarcinoma, Metastatic Gastric Cancer, Gastroesophageal Junction Cancer, Esophageal Adenocarcinoma
- Keywords
- gastric cancer, gastroesophageal junction cancer, esophageal adenocarcinoma
- Phase
- Phase 2/3
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 840 participants (estimated)
- Lead sponsor
- PfizerIndustry (pharma, biotech, devices)
- Study start
- 14 May 2026 (actual)
- Primary completion
- 22 Jul 2031 (estimated)
- Study completion
- 21 Jul 2032 (estimated)
- First posted
- 6 Feb 2026 (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.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Phase 2 Portion | Experimental | Biological: PF-08634404, Drug: ChemotherapyPF-08634404 + Chemotherapy |
| Phase 3: Arm A | Experimental | Biological: PF-08634404, Drug: ChemotherapyPF-08634404 + Chemotherapy |
| Phase 3: Arm B | Active comparator | Drug: Chemotherapy, Biological: NivolumabNivolumab + Chemotherapy |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- 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
Key exclusion criteria (8 listed)
- 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
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 |
|---|---|---|
| PF-08634404Also: SSGJ-707Participants will receive PF-08634404 intravenously. | Biological | Phase 2 Portion, Phase 3: Arm A |
| ChemotherapyParticipants will receive PF-08634404 intravenously in combination with Chemotherapy. | Drug | Phase 2 Portion, Phase 3: Arm A, Phase 3: Arm B |
| NivolumabParticipants will receive Nivolumab intravenously. | Biological | Phase 3: Arm B |
Primary outcome
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.
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.
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.
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.
19 secondary outcomes
Phase 2: Duration of Response (DOR) using RECIST 1.1 as assessed by investigator
Time frame: Approximately 4 years
Phase 2: Progression Free Survival (PFS) using RECIST 1.1 as assessed by investigator
Time frame: Approximately 4 years
Phase 2: Overall Survival (OS)
Time frame: Approximately 4 years
Phase 2: Number of participants with laboratory abnormalities
Time frame: Through 90 days after the last study intervention; Approximately 4 years
Phase 2: Serum concentrations of PF-08634404
Time frame: Approximately 21 months
Phase 2: Incidence of Anti-Drug Antibody (ADA) against PF-08634404
Time frame: Approximately 21 months
Phase 3: ORR using RECIST 1.1 as assessed by BICR
Time frame: Approximately 4 years
Phase 3: ORR using RECIST 1.1 as assessed by investigator
Time frame: Approximately 4 years
Phase 3: Progression free survival (PFS) using RECIST 1.1 as assessed by investigator
Time frame: Approximately 4 years
Phase 3: DOR using RECIST 1.1 as assessed by BICR
Time frame: Approximately 4 years
Phase 3: DOR using RECIST 1.1 as assessed by investigator
Time frame: Approximately 4 years
Phase 3: PFS2 (PFS after next-line therapy) by investigator
Time frame: Approximately 4 years
Phase 3: Number of participants with treatment-emergent adverse events
Time frame: Through 90 days after the last study intervention; Approximately 4 years
Phase 3: Number of participants with laboratory abnormalities
Time frame: Through 90 days after the last study intervention; Approximately 4 years
Phase 3: Serum concentrations of PF-08634404
Time frame: Approximately 21 months
Phase 3: Incidence of ADA against PF-08634404
Time frame: Approximately 21 months
Phase 3: Change from baseline in Functional Assessment of Cancer Therapy - Gastric (FACT-Ga) Total score
Time frame: Approximately 4 years
Phase 3: Time to definitive deterioration in FACT-Ga Total score
Time frame: Approximately 4 years
Phase 3: Time to definitive deterioration in Gastric Cancer Subscale (GaCS) score
Time frame: Approximately 4 years
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 13 Oct 2026.
- To obtain contact information for a study center near you, click here.Link provided by the sponsor.
- Individual participant dataSharing planned: Yes. Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.
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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.
Pfizer CT.gov Call Center study director
Pfizer
102 sites in 10 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2/3 study testing PF-08634404, Chemotherapy and Nivolumab in people with Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction , or Esophageal Adenocarcinoma and Metastatic Gastric Cancer, run by Pfizer at 102 sites in 10 countries.
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 7 inclusion and 8 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: looking for participants now, as of the sponsor's last update on 13 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 102 sites in United States, China, Israel, Spain, Taiwan and 5 more countries. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this combined phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
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 Pfizer CT.gov Call Center (1-800-718-1021, ClinicalTrials.gov_Inquiries@pfizer.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Phase 2: Confirmed Objective response rate (ORR) using RECIST 1.1 as assessed by investigator (time frame: Approximately 4 years). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 13 Oct 2026.