Merkel Cell Carcinoma: An Unusually Immunogenic Cancer Proves Ripe for Immune Therapy.

The article by Banks et al summarizes the current understanding of Merkel cell carcinoma (MCC) immunobiology and treatment strategies. MCC is a rare but often lethal skin cancer that is associated with several risk factors, including immune suppression, advanced age (age. 50 years), and extensive prior sun exposure.Within the past year, multiple independent sequencing studies have revealed that MCC can be caused either by the Merkel cell polyomavirus (MCPyV) or by heavy UV exposure. In most cases of MCC (approximately 80%), MCPyV is clonally integrated in MCC tumor cells and viral oncoproteins drive oncogenesis. The remaining approximately 20% of cases are not associated with MCPyV and seem to be mediated by UV damage, as wholeexome sequencing has revealed that these tumors harbor dramatically high mutational burdens with a distinct UV damage signature. In Australia, with its heavyUV exposure and predominantly white population, this ratio is inverted: the majority of MCC tumors (approximately 75%) are UV induced and MCPyV negative.