A Study to Evaluate Dostarlimab Plus Carboplatin-paclitaxel Versus Placebo Plus Carboplatin-paclitaxel in Participants With Recurrent or Primary Advanced Endometrial Cancer

To join this study, you need to be a woman aged 18 or older with womb cancer that has been confirmed by doctors. Your cancer must either be advanced (Stage III or IV) or have come back after previous treatment (recurrent).

Specifically, if your cancer is advanced, it needs to be Stage IIIA to IIIC1 with clear signs of the disease that doctors can measure, or Stage IIIC1 with certain types of cancer cells like carcinosarcoma, clear cell, serous, or mixed types. If your cancer is Stage IIIC2 or Stage IV, you might also be eligible. If your cancer has come back, it must be the first time it's recurred, and you haven't had other cancer treatments yet for this recurrence, or it came back at least six months after your last treatment.

You also need to be generally well enough to take part, as assessed by your doctor, and your body's organs need to be working properly. For the second part of the study, your blood pressure needs to be normal or well-managed, and you must be able to take medicines by mouth.

If you decide to take part in this study, you will receive different medications depending on which study group you are assigned to. These medications will include specific doses of dostarlimab, carboplatin, paclitaxel, and potentially niraparib, or a placebo (dummy drug) that looks just like the study drugs. You will have regular visits to the clinic for assessments, which will likely include physical examinations, blood tests, and scans to monitor your health and how the treatment is working. The specific schedule of visits and treatments will vary depending on the part of the study you are in, but it will involve a period of active treatment followed by ongoing observation and follow-up. The total duration of your participation, including follow-up, will be clearly explained by the study team.