Bevacizumab and/or Niraparib in Patients With Recurrent Endometrial and/or Ovarian Cancer With ARID1A Mutation

Patients will have tests and exams to see if they are eligible for the clinical trial. If found eligible, the patient will be randomized into one of two groups and receive treatment as follows: If patients are in the first group,they will receive niraparib alone, once daily taken by mouth. If patients are in the second group, they will receive niraparib once daily taken by mouth and infusion of bevacizumab once every 3 weeks. Patients will receive the study treatment as long as there is evidence that the tumor is not growing or spreading and they are not having any unacceptable, bad side effects. Patients will be monitored during treatment with tests and exams and after treatment completion for up to 3 years.