PRIMARY OBJECTIVE:~I. To obtain an estimate of the proportion of patients' progression-free at 16 weeks (16 week progression free survival [PFS] rate) in patients with recurrent ovarian (including fallopian tube and primary peritoneal) or recurrent endometrial cancer following treatment with abemaciclib as a molecularly matched targeted therapy.~SECONDARY OBJECTIVE:~I. To assess objective response rate (ORR) as per Response Evaluation Criteria in Solid Tumors (RECIST), progression free survival (PFS) and safety following treatment with abemaciclib as a molecularly matched targeted therapy.~EXPLORATORY OBJECTIVES:~I. To explore the relationship between response to abemaciclib and somatic gene alterations that lead to CDK4/6 activation in ovarian cancer.~II. To explore the relationship between response to abemaciclib and hormone receptor expression levels as well as somatic gene alterations that lead to CDK4/6 activation in endometrial cancer.~OUTLINE:~Patients receive abemaciclib orally (PO) twice daily (BID) on days 1-28. Patients with tumors that are hormone receptor positive also receive anastrozole or letrozole per standard of care. Cycles repeat every 28 days in the absence of disease progression or unacceptable toxicity.~After completion of study treatment, patients are followed up for 30 days, and then every 12 weeks up to 1 year.
This phase II trial studies how well abemaciclib works in treating patients with ovarian or endometrial cancer that has an activation of the CDK4/6 pathway and that has come back (recurrent). Abemaciclib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Giving abemaciclib may work better for the treatment of recurrent ovarian and endometrial cancer.