Recruiting
Phase 3

PF-08634404 & Chemotherapy

Sponsor:

Pfizer

Code:

NCT07578649

Conditions

Endometrial Neoplasms

Endometrial Cancer

Eligibility Criteria

Sex: Female

Age: 18+

Healthy Volunteers: Not accepted

Interventions

PF-08634404

Pembrolizumab

Standard of Care Chemotherapy

Study Details

Brief 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 (with or without measurable disease) 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

Endometrial Neoplasms

Endometrial Cancer

Study ID

NCT07578649

Start date

Oct 14, 2026

Status verified date

Oct, 2026

Completion date

Jan 30, 2031

Anticipated

Primary completion date

Jun 1, 2029

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: Female

Age: 18+

Healthy Volunteers: Not accepted

Inclusion Criteria:

  • 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 Criteria:

  • 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.

Study Design

Enrollment

600 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: PF-08634404 plus Chemotherapy

PF-08634404 plus Chemotherapy, followed by PF-08634404 maintenance therapy

active comparator: Pembrolizumab plus Chemotherapy

Pembrolizumab plus Chemotherapy, followed by Pembrolizumab maintenance therapy

Interventions

PF-08634404

Solution for IV infusion

Pembrolizumab

Solution for IV infusion

Standard of Care Chemotherapy

Solution for IV infusion

Primary outcome measure

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

Central Contacts and Locations

Central contacts

Pfizer CT.gov Call Center

1-800-718-1021ClinicalTrials.gov_Inquiries@pfizer.com

Locations

Jupiter Medical Center/ Anderson Family Cancer Institute

Recruiting

Jupiter, Florida, United States, 33458

Orlando Health Ambulatory Care Center

Recruiting

Orlando, Florida, United States, 32806

Orlando Health Cancer Institute

Recruiting

Orlando, Florida, United States, 32806

Orlando Health Orlando Regional Medical Center

Recruiting

Orlando, Florida, United States, 32806

Orlando Health Winnie Palmer Hospital for Women & Babies

Recruiting

Orlando, Florida, United States, 32806

Minnesota Oncology Hematology, PA

Recruiting

Coon Rapids, Minnesota, United States, 55433

Minnesota Oncology Hematology, PA

Recruiting

Edina, Minnesota, United States, 55435

Minnesota Oncology Hematology, PA

Recruiting

Maple Grove, Minnesota, United States, 55369

Minnesota Oncology Hematology, PA

Recruiting

Maplewood, Minnesota, United States, 55109

Minnesota Oncology Hematology, PA

Recruiting

Woodbury, Minnesota, United States, 55125

The Center of Hope

Recruiting

Reno, Nevada, United States, 89511

White Plains Hospital

Recruiting

White Plains, New York, United States, 10601

Miami Valley Hospital South

Recruiting

Centerville, Ohio, United States, 45459

Northwest Cancer Specialists, P.C.

Recruiting

Happy Valley, Oregon, United States, 97015

Northwest Cancer Specialists, P.C.

Recruiting

Portland, Oregon, United States, 97227

Northwest Cancer Specialists, P.C.

Recruiting

Tigard, Oregon, United States, 97223

Sarah Cannon Research Institute- Pharmacy

Recruiting

Nashville, Tennessee, United States, 37203

SCRI Oncology Partners

Recruiting

Nashville, Tennessee, United States, 37203

Texas Oncology - West Texas

Recruiting

Abilene, Texas, United States, 79606

Texas Oncology-West Texas

Recruiting

Amarillo, Texas, United States, 79124

Texas Oncology - Central South

Recruiting

Austin, Texas, United States, 78731

Texas Oncology - Central South

Recruiting

Austin, Texas, United States, 78745

Texas Oncology - Central South

Recruiting

Austin, Texas, United States, 78758

Texas Oncology-West Texas

Recruiting

El Paso, Texas, United States, 79902

Texas Oncology - West Texas

Recruiting

El Paso, Texas, United States, 79915

Texas Oncology - West Texas

Recruiting

El Paso, Texas, United States, 79938

Texas Oncology - Central South

Recruiting

Harlingen, Texas, United States, 78550

US Oncology Investigational Products Center (IPC)

Recruiting

Irving, Texas, United States, 75063

Texas Oncology - Central South

Recruiting

McAllen, Texas, United States, 78503

Texas Oncology-West Texas

Recruiting

Midland, Texas, United States, 79701

Texas Oncology - West Texas

Recruiting

Odessa, Texas, United States, 79761

Texas Oncology - Central South

Recruiting

Waco, Texas, United States, 76712

Texas Oncology - Central South

Recruiting

Weslaco, Texas, United States, 78596

Texas Oncology-West Texas

Recruiting

Wichita Falls, Texas, United States, 76310

Virginia Oncology Associates

Recruiting

Chesapeake, Virginia, United States, 23320

Virginia Oncology Associates

Recruiting

Newport News, Virginia, United States, 23606

Virginia Oncology Associates

Recruiting

Norfolk, Virginia, United States, 23502

Virginia Oncology Associates

Recruiting

Suffolk, Virginia, United States, 23435

Virginia Oncology Associates

Recruiting

Williamsburg, Virginia, United States, 23188

Northwest Cancer Specialists, P.C.

Recruiting

Vancouver, Washington, United States, 98684

Minnesota Oncology Hematology, P.A.

Recruiting

Hudson, Wisconsin, United States, 54016

More Information

Sponsor

Pfizer

Last update posted

Oct 30, 2026

Last verified

Oct, 2026

Keywords

  • Recurrent Endometrial Carcinoma
  • Endometrial Neoplasms
  • Advanced Endometrial Carcinoma
  • Advanced or Recurrent Endometrial Cancer
  • pMMR

Trial information was received from ClinicalTrials.gov and was last updated on 2026-10-31. This information was provided to ClinicalTrials.gov by Pfizer on 2026-10-30. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.