Dostarlimab is a type of medication known as an immune checkpoint inhibitor. It works by helping your immune system recognize and attack cancer cells. In this trial, dostarlimab is being tested to see if it can help treat metastatic or recurrent endometrial or ovarian carcinosarcoma when used in combination with another medication.

Niraparib is a medication that belongs to a class of drugs called PARP inhibitors. It works by blocking a protein that cancer cells need to repair themselves, which can help stop the cancer from growing. In this study, niraparib is being used both on its own and in combination with dostarlimab to see how effective it is in treating certain types of cancer.

Endometrial Carcinosarcoma – Endometrial carcinosarcoma is a rare and aggressive form of cancer that arises from the uterus. It contains both carcinomatous (epithelial) and sarcomatous (mesenchymal) components. The disease typically begins in the lining of the uterus and can invade deeper tissues. It may spread to other parts of the body, including the lymph nodes, lungs, and liver. The progression of the disease can vary, but it often involves rapid growth and spread. Symptoms may include abnormal uterine bleeding, pelvic pain, and a noticeable mass in the pelvic area.

Ovarian Carcinosarcoma – Ovarian carcinosarcoma is a rare and aggressive cancer that originates in the ovaries. It is characterized by the presence of both carcinomatous and sarcomatous tissue. The disease often progresses quickly, with potential spread to the abdominal cavity, lymph nodes, and distant organs. Symptoms can include abdominal swelling, pain, and changes in bowel or bladder habits. The disease may also cause unexplained weight loss and fatigue. Its progression is marked by the rapid growth of tumors and potential metastasis.