The EAY191-N4 clinical study, A Randomized Trial of Selumetinib and Olaparib or Selumetinib Alone in Patientswith Recurrent or Persistent RAS Pathway Mutant Ovarian and Endometrial Cancers, part of the ComboMATCH precision medicine initiative, is open for women who have recurrent or persistent ovarian and endometrial with a RAS pathway mutation, including activating mutations in KRAS, NRAS, HRAS, BRAF, MEK1, and MEK2, or in activating mutations in NF1. The trial will be comparing the combination of the MEK inhibitor Selumetinib and the PARP inhibitor Olaparib to Selumetinib alone for this patient population. The study will be occurring in two different cohorts. Cohort 1 will consist of patients with ovarian cancer and Cohort 2 will include patients with endometrial cancer.