Polyomavirus-positive Merkel cell carcinoma: the beginning of the beginning

Merkel cell carcinoma (MCC) is an aggressive, fast-growing, highly metastatic neuroendocrine skin cancer. The Merkel cell polyomavirus (MCPyV) is an oncogenic driver in the majority of MCC tumors. In this issue of the JCI, Hansen and authors report on their tracking of [CD8.sup.+] T cells reactive to MCPyV T antigen (T-Ag) in the peripheral blood of 26 patients with MCC who were undergoing frontline anti-programmed cell death protein-1 (anti-PD-1) immunotherapy. They discovered unique T cell epitopes and used the power of bar-coded tetramers to portray immune checkpoint inhibitor-induced immunogenicity as a predictor of clinical response. These findings provide the foundation for therapeutic possibilities for MCC, including vaccines and adoptive T cell- and T cell receptor-driven (TCR-driven) treatments.
MCC is a rare and aggressive neuroendocrine tumor Merkel cell carcinoma (MCC) is an aggressive, fast-growing, highly metastatic neuroendocrine tumor. There are two pathways to the oncogenesis of MCC. One [...]