Viral oncoprotein antibodies as a marker for recurrence of Merkel cell carcinoma: A prospective validation study

BACKGROUND Merkel cell carcinoma (MCC) is an aggressive skin cancer with a recurrence rate of >40%. Of the 2000 MCC cases per year in the United States, most are caused by the Merkel cell polyomavirus (MCPyV). Antibodies to MCPyV oncoprotein (T‐antigens) have been correlated with MCC tumor burden. The present study assesses the clinical utility of MCPyV‐oncoprotein antibody titers for MCC prognostication and surveillance. METHODS MCPyV‐oncoprotein antibody detection was optimized in a clinical laboratory. A cohort of 219 patients with newly diagnosed MCC were followed prospectively (median follow‐up, 1.9 years). Among the seropositive patients, antibody titer and disease status were serially tracked. RESULTS Antibodies to MCPyV oncoproteins were rare among healthy individuals (1%) but were present in most patients with MCC (114 of 219 patients [52%]; P