This study compares two treatments for ovarian, fallopian tube, or peritoneal cancer. The first treatment uses a new medicine called Mirvetuximab Soravtansine (MIRV) that targets and kills cancer cells. It is combined with a drug called Bevacizumab. The second treatment uses only Bevacizumab. The study checks if the new combination is safe and works better as a maintenance therapy, which means it helps keep the cancer from coming back after initial treatment. Participants must have a type of cancer that responds to platinum-based chemotherapy and have a specific protein called FRα on their cancer cells. The study requires tests to confirm these conditions.

• The study is open to adults aged 18 and older who meet specific health criteria.
• Participants must be willing to provide tissue samples and undergo necessary tests.
• The study involves regular visits and tests, but participants may benefit from the new treatment.