Study Comparing Pembrolizumab to Chemotherapy in Advanced or Recurrent Endometrial Cancer with Mismatch Repair Deficiency

Inclusion Criteria

• Diagnosed with advanced or recurrent endometrial cancer that cannot be surgically removed and has a specific genetic feature called mismatch repair deficiency (dMMR).
• Cancer must be visible on scans, either as measurable or non-measurable disease.
• No previous systemic chemotherapy for endometrial cancer, except:
  • One prior line of platinum-based chemotherapy if the cancer returned at least 6 months after the last dose.
  • Previous radiation therapy is allowed if completed more than 2 weeks before starting the study treatment.
  • Previous hormonal therapy is allowed if stopped at least 1 week before starting the study treatment.
• Good overall health with an ECOG performance status of 0 or 1.
• Not pregnant or breastfeeding and willing to use effective birth control during and after the study.
• Negative pregnancy test before starting the study treatment.
• Provide a tumor sample for genetic testing.
• If positive for Hepatitis B, must have undetectable viral load after treatment.
• If previously infected with Hepatitis C, must have undetectable viral load.

Exclusion Criteria

• Have a different type of uterine cancer, such as sarcomas or neuroendocrine tumors.
• Have endometrial cancer without the mismatch repair deficiency (pMMR).
• Eligible for surgery or radiation with the intent to cure.
• Previously treated with certain immunotherapy drugs targeting PD-1, PD-L1, or similar pathways.
• Received prior systemic treatment for advanced or metastatic endometrial cancer.
• Not fully recovered from a major surgery.
• Received a live vaccine within 30 days before starting the study.
• Participating in another clinical trial or using an investigational device recently.
• Have an immune system deficiency or taking long-term steroids or immunosuppressive drugs.
• Have another active cancer requiring treatment in the past 3 years, except for certain skin cancers.
• Have active cancer spread to the brain or spinal cord.
• Allergic to any study medications.
• Have an autoimmune disease needing treatment in the past 2 years.
• Have lung disease or pneumonitis needing steroids.
• Have an active infection needing treatment.
• Have HIV infection.
• Have had an organ transplant.