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A Study of PF-08634404 for Advanced or Recurrent Endometrial Cancer

This study is for women with advanced or recurrent endometrial cancer where the DNA "spell-checker" (MMR system) is working normally (MMR-proficient). It aims to see if a medicine called PF-08634404, when given with chemotherapy, works better than another medicine called pembrolizumab plus chemotherapy. The main goal is to measure how long people live without their cancer growing or spreading, over about 36 months. You may be able to join if you are at least 18 years old and have this type of endometrial cancer that has spread or come back. The study plans to enroll 600 participants, but its current status is unclear.

Study design
This interventional study is comparing two treatment combinations in about 600 participants. It is testing PF-08634404 plus chemotherapy against pembrolizumab plus chemotherapy.
What's involved
Not specified in the trial record.
Compensation
Not stated in the trial record.
Follow-up
Participants will be followed for approximately 36 months to assess how long they live without their cancer progressing.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT07578649

Symbiotic-GYN-18: A Study to Learn About the Study Medicine Called PF-08634404 in Combination With Chemotherapy in Adult Participants With Advanced or Recurrent MMR-proficient Endometrial Cancer

Not Yet Recruiting
PHASE3Ages 18+InterventionalTreatment
Pfizer
~600 participants
Updated 2026-08-17 on ClinicalTrials.gov
What's tested:PF-08634404PembrolizumabStandard of Care Chemotherapy

At a glance

Recruiting sites
0 of 1 listed site is recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Progression-Free Survival (PFS) using RECIST v1.1 as assessed by Blinded Independent Central Review (BICR)
Measured over Approximately 36 months

Conditions

Endometrial Neoplasms
Endometrial Cancer

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Endometrial CarcinomaEndometrial carcinosarcomaMRC1 wt Allele

Where it's being run

1 sites across 1 states
Saitama1

Study leadership

  • Pfizer CT.gov Call Center · STUDY_DIRECTOR · Pfizer

Who to contact

Pfizer CT.gov Call Center
[email protected]
1-800-718-1021
Email the study team

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Eligibility criteria

Inclusion

Women ≥18 years of age who are confirmed not pregnant at screening.
Histologically or cytologically confirmed endometrial cancer that is recurrent or advanced; carcinosarcomas are eligible but pure sarcomas are excluded.
Newly diagnosed FIGO Stage III disease with measurable disease per RECIST v1.1, newly diagnosed FIGO Stage IV disease with or without measurable disease, or recurrent disease with or without measurable disease for which curative treatment with surgery and/or radiotherapy is unlikely.
For participants with recurrent disease, prior adjuvant systemic anti-cancer therapy is allowed if relapse occurred more than 6 months after the last dose.
Must provide tumor tissue for prospective central assessment of MMR and p53 status.
Proficient mismatch repair (pMMR) endometrial cancer as determined by central testing.
Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.
Life expectancy of at least 12 weeks.
Adequate organ function as defined in the protocol.

Exclusion

Prior systemic therapy for first-line advanced or recurrent endometrial cancer.
Prior immunotherapy or anti-angiogenic therapy.
Deficient mismatch repair (dMMR) endometrial cancer by central testing.
Active or untreated central nervous system (CNS) metastases; participants with previously treated and clinically stable brain metastases may be eligible if not requiring steroids and without evidence of progression.
Clinically significant risk of bleeding or fistula, including a history of severe bleeding disorders.
History of another malignancy within 3 years, except for cancers with negligible risk of recurrence or death.
History of allogeneic organ or hematopoietic stem cell transplantation; active autoimmune disease requiring systemic treatment within the past 2 years; or history of immunodeficiency
Interstitial lung disease, pneumonitis, or clinically significant pulmonary disease
Uncontrolled or significant cardiovascular, metabolic, renal, hepatic, or vascular disease
Active or uncontrolled infection.
Recent major surgery or severe trauma within protocol-defined washout periods.

What this trial measures

  • Progression-Free Survival (PFS) using RECIST v1.1 as assessed by Blinded Independent Central Review (BICR)Approximately 36 months

    PFS by BICR is defined as the time from the date of randomization to the date of first documented disease progression per RECIST v1.1 as assessed by BICR, or death due to any cause, whichever occurs first.