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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

NCT07578649 · Status: NOT_YET_RECRUITING · Phase: PHASE3 · Type: INTERVENTIONAL · Enrollment: 600

Last updated 2026-05-19

No results posted yet for this study

Summary

This study is being conducted to assess whether the study medicine PF 08634404, given in combination with chemotherapy, improves outcomes compared with another medicine called pembrolizumab plus chemotherapy. Chemotherapy is a type of cancer treatment that uses medicines to destroy cancer cells or stop them from growing.

Our bodies have a built-in DNA "spell-checker," called the mismatch repair (MMR) system, that fixes genetic mistakes. In most endometrial cancers, this system works normally, and these cancers are called MMR-proficient (pMMR). However, pMMR tumors are harder for the immune system to recognize and attack. When endometrial cancer has spread beyond the uterus or comes back after previous treatment, it is called advanced or recurrent endometrial cancer. This study is for adults with mismatch repair-pMMR advanced or recurrent endometrial cancer.

Participants must meet key criteria, including:

* Women who are 18 years or older, and not pregnant at the time of joining the study
* pMMR endometrial cancer only
* Measurable Stage III disease, Stage IV disease (with or without measurable disease) per FIGO staging, a system doctors use to describe how far cancer has spread in the body, or recurrent endometrial cancer
* Has not received chemotherapy except for chemotherapy given after the main surgery and more than 6 months before relapse
* Be in good enough health to receive study treatment. Approximately 600 adult women will be enrolled. Each participant will be randomly assigned (like a flip of the coin) to one of two treatment groups, with about half in each group. The study is open, meaning both the doctors and participants know what treatment is being given. Participants will receive their assigned treatment through intravenous infusions (medicine is given directly into a vein). The treatment will be given in cycles.

Experimental Group will receive new study medicine called PF-08634404 plus chemotherapy. It will be followed by PF 08634404 alone for up to 2 years (35 cycles).

Control Group will receive an approved medicine called pembrolizumab plus chemotherapy. It will be followed by pembrolizumab alone for up to 2 years (20 cycles).

The study will include regular visits for:

* Participants will have regular visits to the study site for treatment, health checks, and tests.
* After stopping treatment, participants will come for a final visit within a month to check their health and review any reactions.
* Follow-up will continue every 12 weeks by phone or in person or by reviewing health records. This helps check health and any new treatments.
* Tests will be done every 9 weeks during the first 104 weeks to see how the cancer is responding. After that, tests will be done every 12 weeks.

Conditions

Interventions

BIOLOGICAL

PF-08634404

Solution for IV infusion

BIOLOGICAL

Pembrolizumab

Solution for IV infusion

DRUG

Standard of Care Chemotherapy

Solution for IV infusion

Sponsors & Collaborators

  • GOG Foundation

    collaborator NETWORK

  • Pfizer

    lead INDUSTRY

Principal Investigators

  • Pfizer CT.gov Call Center · Pfizer

Study Design

Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Model
PARALLEL

Eligibility

Min Age
18 Years
Sex
FEMALE
Healthy Volunteers
No

Timeline & Regulatory

Start
2026-10-09
Primary Completion
2029-06-01
Completion
2031-01-30
FDA Drug
Yes

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT07578649 on ClinicalTrials.gov