Merkel Cell Polyomavirus Antibody Titer Predicts Recurrence-Free Survival.

BACKGROUND Merkel cell polyomavirus (MCPyV) is associated with the development of Merkel cell carcinoma (MCC). Antibody (MCPyV-Ab) titers may have prognostic implications. This study evaluated the impact of the presence or absence of MCPyV-Ab on the 2-year overall survival (OS) and disease-free survival (DFS) of MCC patients. METHODS This single-center, IRB-approved, retrospective cohort study evaluated 51 adult patients with MCC from 2014 to 2021 using a prospectively maintained database. Patients were compared by MCPyV-Ab status, and Kaplan-Meier analysis was used to evaluate 2-year OS and DFS. RESULTS Of the 51 patients, 13 (25.4%) were seropositive, 41 (80.4%) underwent wide excision, 40 (80.0%) received radiotherapy, and 43 (84.3%) received multimodal therapy. The median follow-up period was 15.5 months (range 1-69.5 months). The median 2-year OS of the entire cohort was not reached. The median 2-year OS was not reached for either the seronegative or the seropositive patients. The difference in 2-year OS between the groups was not statistically significant (p = 0.37). Eight patients, all seronegative, were never rendered disease-free and were removed from recurrence analysis. The seropositive patients experienced no recurrences. Of the 30 seronegative patients, 9 (30.0%) experienced recurrence. The median 2-year DFS of the entire cohort was not reached. The median 2-year DFS of the seronegative group was 22.2 months. The 2-year DFS was not reached for the seropositive cohort. Seropositivity conferred a significantly better 2-year DFS than seronegativity (p = 0.04). CONCLUSION The MCPyV-Ab seropositive patients demonstrated improved 2-year DFS. The seropositive patients showed a strong trend toward improved 2-year OS, although the difference not statistically significant. This study substantiated the value of MCPyV-Ab assessment for MCC.