Participants who join the study will first have samples of their blood and tumor tissue collected for biomarker testing. The testing will involve a method called sequencing. This test will look for changes in the genes of your tumor. The results of the testing will be what is called the participant's molecular profile.~All participants will first receive bevacizumab and niraparib for 3 cycles. A cycle will be 21-days in length.~Once the participant's molecular profile has been determined, the study doctor will discuss the results with the participants and they may be referred to a genetic counsellor.~Participants will then be assigned to a study cohort (group) and receive a combination of the study drugs based on the results of their genetic testing:~Cohort A: Participants who do not have the required gene changes will be assigned to receive niraparib, bevacizumab, and dostarlimab~Cohort B: Participants who have certain gene changes will receive paclitaxel, bevacizumab, and dostarlimab.~Cohort C: If the participant and the study doctor think that the participant is benefitting from the combination of bevacizumab and niraparib, or the molecular profile shows that bevacizumab and niraparib is the most suitable, the participant may continue to receive this drug combination.~Participants will receive the study drug combination until disease worsening or they meet the criteria for discontinuation.
The purpose of this research study is to see how useful it is to look at biomarkers in the blood and tumor tissue of participants with ovarian, fallopian tube or primary peritoneal cancer who have previously received treatment with a drug called a PARP inhibitor, and using the results to determine the best treatment for these participants. Biomarkers are molecules such as genes (molecules that contain instructions for the development and function of cells in the body) and proteins that may be used to see how well a body responds to certain treatments.