Pembrolizumab in Treating Patients With Desmoplastic Melanoma That Can or Cannot Be Removed by Surgery

This pilot phase II trial studies how well pembrolizumab works in treating patients with desmoplastic melanoma (DM) that can be removed by surgery (resectable) or cannot be removed by surgery (unresectable). Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread.

PRIMARY OBJECTIVES: I. To evaluate the pathologic complete response rate (pCR) in patients with resectable desmoplastic melanoma treated with neoadjuvant pembrolizumab (MK-3475). (Cohort A) II. To evaluate the complete response rate (confirmed and unconfirmed) in patients with unresectable desmoplastic melanoma treated with pembrolizumab (MK-3475). (Cohort B) SECONDARY OBJECTIVES: I. To estimate the 9 week response rate (RR) (unconfirmed complete and partial responses) among patients with measurable disease. (Cohort A) II. To estimate the median overall survival (OS). (Cohort A) III. To evaluate safety and tolerability of pembrolizumab (MK-3475) in the neoadjuvant setting. (Cohort A) IV. To estimate the median progression-free survival (PFS). (Cohort B) V. To estimate the median overall survival (OS). (Cohort B) VI. To evaluate safety and tolerability of pembrolizumab (MK-3475) in this setting. (Cohort B) OTHER OBJECTIVES: I. To evaluate the hypothesis that higher mutational load in the patient derived baseline tumor biopsy samples is associated with higher pathologic complete response (pCR). II. To evaluate T cell infiltration into the tumors and circulating tumor deoxyribonucleic acid (DNA) profile from blood samples in DM patients and correlate with response to programmed cell death protein 1 (PD-1) blockade. III. To evaluate the clonality of tumor infiltrating T cells in DM patients and correlate with response to PD-1 blockade. IV. To evaluate adaptive immune resistant mechanism in DM tumors. OUTLINE: Patients are enrolled to 1 of 2 cohorts. COHORT A: Patients receive pembrolizumab intravenously (IV) over 30 minutes on day 1. Treatment repeats every 21 days for up to 3 cycles. Patients with potentially resectable disease undergo surgery. Patients with tumor progression and unresectable disease may receive one additional cycle of pembrolizumab. COHORT B: Patients with unresectable disease receive pembrolizumab IV over 30 minutes on day 1. Treatment repeats every 21 days for up to 34 cycles in the absence of disease progression or toxicity. Patients undergo computed tomography (CT) scan and may undergo position emission tomography (PET) and magnetic resonance imaging (MRI) throughout the study. Patients also undergo blood sample collection at screening and tumor biopsy throughout the study. After completion of study treatment, patients are followed up at 6 weeks after the last dose, then every 12 weeks to the end of the first year, then every 6 months to the end of the fifth year after registration. After progression, patients are followed every 6 months for up to 2 years from the date of registration, then annually thereafter until 5 years from registration.