Pembrolizumab in Treating Patients With Advanced Merkel Cell Cancer

This phase II trial studies how well pembrolizumab works in treating patients with Merkel cell cancer that cannot be removed by surgery or controlled with treatment, or has spread to other parts of the body. Pembrolizumab may stimulate the immune system to identify and destroy cancer cells.

PRIMARY OBJECTIVES: I. To determine the clinical efficacy of MK-3475 (pembrolizumab) as the first systemic intervention for patients with advanced Merkel cell carcinoma (MCC). SECONDARY OBJECTIVES: I. To determine the clinical activity of MK-3475 as the first systemic intervention for patients with advanced MCC. TERTIARY OBJECTIVES: I. To determine the immune correlates of the clinical activity of MK-3475. OUTLINE: Patients receive pembrolizumab intravenously (IV) over 30 minutes on day 1. Treatment repeats every 21 days for up to 24 months in the absence of disease progression\* or unacceptable toxicity. \* NOTE: Patients with confirmed disease progression may continue to receive treatment if they are otherwise clinically stable until there is an increase in tumor burden of 25% or more following initial confirmation of progression. Under exceptional circumstances, and with protocol principal investigator (P.I.) and Cancer Immunotherapy Trials Network (CITN) P.I. approval, patients may receive treatment beyond 2 years. After completion of study treatment, patients are followed up at 30 days and then every 3 months for 1 year, every 6 months for 2 years, annually until the patient has completed 3 years of follow up for disease assessment, and then every 12 weeks.