Pembrolizumab and Sunitinib Malate in Treating Participants With Refractory Metastatic or Unresectable Thymic Cancer

This phase II trial studies how well pembrolizumab and sunitinib malate work in treating participants with thymic cancer that has spread to other places in the body or cannot be removed by surgery and does not respond to treatment. Monoclonal antibodies, such as pembrolizumab, may interfere with the ability of tumor cells to grow and spread. Sunitinib malate may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Giving pembrolizumab and sunitinib malate may work better in treating thymic cancer.

PRIMARY OBJECTIVES: I. To evaluate the efficacy of pembrolizumab and sunitinib malate (sunitinib) for the treatment of patients with thymic carcinoma that have progressed on prior treatment as measured by objective response rate. SECONDARY OBJECTIVES: I. To evaluate the safety profile and toxicity of combination pembrolizumab and sunitinib malate as per Common Terminology Criteria for Adverse Events (CTCAE) version (v) 4.0. II. To evaluate the progression free survival (PFS) and overall survival (OS) of patients treated with combination pembrolizumab and sunitinib. EXPLORATORY OBJECTIVES: I. To determine objective response rate (ORR), PFS, and OS by PD-L1 expression \> 50% tumor proportion score (TPS) (by 22C3 assay) II. To determine whether sunitinib treatment leads to increase in PD-L1 expression and tumor infiltrating lymphocytes and decrease in myeloid-derived suppressor cells (MDSC) in both tumor and peripheral blood. OUTLINE: Participants receive pembrolizumab intravenously (IV) over 30 minutes on day 1 and sunitinib malate orally (PO) daily on days 1-14. Courses repeat every 21 days for 24 months in the absence of disease progression or unacceptable toxicity. After completion of the study treatment, participants are followed up for 30 days, every 6 weeks for 1 year, and every 9 or 12 weeks thereafter.