RecruitingPhase 2Phase 3NCT07392892

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

Sponsor

Pfizer

Enrollment

840 participants

Start Date

Apr 28, 2026

Study Type

INTERVENTIONAL

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.

Eligibility

Min Age: 18 Years

Inclusion Criteria7

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 Criteria8

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

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Interventions

BIOLOGICALPF-08634404

Participants will receive PF-08634404 intravenously.

DRUGChemotherapy

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

BIOLOGICALNivolumab

Participants will receive Nivolumab intravenously.