Testing the Use of the Combination of Selumetinib and Olaparib or Selumetinib Alone Targeted Treatment for RAS Pathway Mutant Recurrent or Persistent Ovarian and Endometrial Cancers, A ComboMATCH Treatment Trial

PRIMARY OBJECTIVES: I. Compare progression free survival of combination of olaparib and selumetinib sulfate (selumetinib) to selumetinib alone in patients with RAS mutant ovarian cancer. (Cohort 1) II. Compare progression free survival of combination of olaparib and selumetinib to selumetinib alone in patients with RAS mutant endometrial cancer. (Cohort 2) SECONDARY OBJECTIVES: I. Determine safety of both arms per Common Terminology Criteria for Adverse Events (CTCAE) version (v)5.0. II. Compare objective response rate per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 between the two arms. III. Determine rate of objective response per RECIST 1.1 in those patients that crossover from the single agent arm to the combination arm. IV. Report duration of response of the two treatment arms. V. Collect tissue and provide it to the ComboMATCH Registration protocol to assess concordance between the diagnostic tumor mutation profile generated by the designated laboratories, the pre-treatment biopsy mutation profile, and the pre-treatment circulating tumor (ct)DNA mutation profile from plasma, as described in ComboMATCH Registration protocol. For this treatment substudy, the outcome objective will be to report the proportion of cases providing sufficient tissue for that integrated scientific activity in the ComboMATCH Registration protocol. TRANSLATIONAL OBJECTIVE: I. To assess association of baseline genomic and transcriptomic status with response and resistance to therapy. OUTLINE: Patients in both cohorts are randomized to 1 of 2 arms. ARM I: Patients receive selumetinib orally (PO) twice daily (BID) and olaparib PO BID on days 1-28. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients also undergo a tumor biopsy and blood collection during screening and on study, as well as echocardiogram (ECHO) or multigated acquisition (MUGA), and computed tomography (CT) scans throughout the trial. Patients may undergo bone marrow aspiration or biopsy as clinically indicated. ARM II: Patients receive selumetinib PO BID on days 1-28. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity. Patients who experience progression may elect to cross over to Arm I provided they have not had dose limiting toxicities to monotherapy selumetinib. Patients also undergo a tumor biopsy and blood collection during screening and on study, as well as ECHO or MUGA, and CT scans throughout the trial. Patients may undergo bone marrow aspiration or biopsy as clinically indicated. After completion of study treatment, patients are followed up every 3 months for 2 years and then every 6 months for 3 years.