Immune evasion mechanisms and immune checkpoint inhibition in advanced merkel cell carcinoma.

Schadendorf D, Nghiem P, Bhatia S, Hauschild A, Saiag P, Mahnke L, Hariharan S, Kaufman HL.

Oncoimmunology. 2017 Aug 31;6(10):e1338237.

PMID: 29123950

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Merkel cell carcinoma (MCC) is a rare skin cancer caused by Merkel cell polyomavirus (MCPyV) infection and/or ultraviolet radiation-induced somatic mutations. The presence of tumor-infiltrating lymphocytes is evidence that an active immune response to MCPyV and tumor-associated neoantigens occurs in some patients. However, inhibitory immune molecules, including programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1), within the MCC tumor microenvironment aid in tumor evasion of T-cell-mediated clearance. Unlike chemotherapy, treatment with anti-PD-L1 (avelumab) or anti-PD-1 (pembrolizumab) antibodies leads to durable responses in MCC, in both virus-positive and virus-negative tumors. As many tumors are established through the evasion of infiltrating immune-cell clearance, the lessons learned in MCC may be broadly relevant to many cancers.

Oncoimmunology. 2017 Aug 31;6(10):e1338237.