NCT07392892|RecruitingPhase 2DMCFDA Drug

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

Pfizer ClinicalTrials.gov

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2 other identifiers

C64610162025-524717-86-00

Study Type

interventional

Target

840

Locations

6 countries

Sites

Timeline

RegisteredFeb 2026

StartedMay 2026

CompletionJul 2032

Brief 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. 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.

Trial Health

On Track

Trial Health Score

Automated assessment based on enrollment pace, timeline, and geographic reach

Enrollment

840

participants targeted

Target at P75+ for phase_2

Timeline

74mo left

Started May 2026

Longer than P75 for phase_2

Geographic Reach

6 countries

71 active sites

Status

recruiting

Health score is calculated from publicly available data and should be used for screening purposes only.

Trial Relationships

Click on a node to explore related trials.

Study Timeline

Key milestones and dates

6.2 years study duration

Study Progress1%

May 2026Jul 2032

First Submitted

Initial submission to the registry

January 30, 2026

Completed

7 days until next milestone

First Posted

Study publicly available on registry

February 6, 2026

Completed

3 months until next milestone

Study Start

First participant enrolled

May 14, 2026

Completed

5.2 years until next milestone

Primary Completion

Last participant's last visit for primary outcome

July 22, 2031

Expected

1 year until next milestone

Study Completion

Last participant's last visit for all outcomes

July 21, 2032

Last Updated

June 12, 2026

Status Verified

June 1, 2026

Enrollment Period

5.2 years

First QC Date

January 30, 2026

Last Update Submit

June 10, 2026

Conditions

Untreated Advanced or Metastatic Gastric, Gastroesophageal Junction , or Esophageal Adenocarcinoma Metastatic Gastric Cancer Gastroesophageal Junction Cancer Esophageal Adenocarcinoma

Keywords

gastric cancergastroesophageal junction canceresophageal adenocarcinoma

Outcome Measures

Primary Outcomes (4)

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.
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.
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.
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.
Approximately 4 years

Secondary Outcomes (19)

Phase 2: Duration of Response (DOR) using RECIST 1.1 as assessed by investigator
Approximately 4 years
Phase 2: Progression Free Survival (PFS) using RECIST 1.1 as assessed by investigator
Approximately 4 years
Phase 2: Overall Survival (OS)
Approximately 4 years
Phase 2: Number of participants with laboratory abnormalities
Through 90 days after the last study intervention; Approximately 4 years
Phase 2: Serum concentrations of PF-08634404
Approximately 21 months
+14 more secondary outcomes

Study Arms (3)

Phase 2 Portion

EXPERIMENTAL

PF-08634404 + Chemotherapy

Biological: PF-08634404Drug: Chemotherapy

Phase 3: Arm A

EXPERIMENTAL

PF-08634404 + Chemotherapy

Biological: PF-08634404Drug: Chemotherapy

Phase 3: Arm B

ACTIVE COMPARATOR

Nivolumab + Chemotherapy

Drug: ChemotherapyBiological: Nivolumab

Interventions

NivolumabBIOLOGICAL

Participants will receive Nivolumab intravenously.

Phase 3: Arm B

PF-08634404BIOLOGICAL

Participants will receive PF-08634404 intravenously.

Also known as: SSGJ-707

Phase 2 PortionPhase 3: Arm A

ChemotherapyDRUG

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

Phase 2 PortionPhase 3: Arm APhase 3: Arm B

Eligibility Criteria

Age18 Years+

Sexall

Healthy VolunteersNo

Age GroupsAdult (18-64), Older Adult (65+)

You may qualify if:

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

You may not qualify if:

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

Contact the study team to confirm eligibility.

Sponsors & Collaborators

Pfizerlead