This pilot phase II trial studies how well pembrolizumab works in treating patients with desmoplastic melanoma (DM) that can or cannot be removed by surgery. Monoclonal antibodies, like pembrolizumab, may block specific proteins which may strengthen the immune system and control tumor growth.
I. To evaluate the pathologic complete response rate (pCR) in patients with resectable desmoplastic melanoma treated with neoadjuvant MK-3475 (pembrolizumab). (Cohort A)
II. To evaluate the complete response rate (confirmed and unconfirmed) in patients with unresectable desmoplastic melanoma treated with MK-3475 (pembrolizumab). (Cohort B)
I. To estimate the 9 week response rate (RR) (unconfirmed complete and partial responses). (Cohort A)
II. To estimate the median overall survival (OS). (Cohort A)
III. To evaluate safety and tolerability of MK-3475 (pembrolizumab) 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 MK-3475 (pembrolizumab) in this setting. (Cohort B)
I. To evaluate the hypothesis that higher mutational load in the patient derived baseline tumor biopsy samples is associated with higher response rate (RR).
II. To evaluate T cell infiltration into the tumors 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.
COHORT A: Patients receive pembrolizumab intravenously (IV) over 30 minutes on day 1. Treatment repeats every 21 days for up to 3 courses. Patients with potentially resectable disease undergo surgery. Patients with tumor progression and unresectable disease, receive one additional course of pembrolizumab.
COHORT B: Patients with unresectable disease receive pembrolizumab IV over 30 minutes on day 1. Treatment repeats every 21 days in the absence of disease progression or toxicity.
After completion of study treatment, patients are followed up at 6 and 12 weeks, then every 3 months for 1 year, and every 6 months for 4 years.