The prognostic value of the Merkel cell polyomavirus serum antibody test: A dual institutional observational study.

Background: Merkel cell carcinoma (MCC) is an aggressive cancer with often poor outcomes. Limited biomarkers exist for predicting clinical outcomes. The Merkel cell polyomavirus (MCPyV) serum antibody test (AMERK) has shown potential for indicating better recurrence‐free survival in a single‐institution study. The study aimed to evaluate the link between initial AMERK serostatus and survival. Secondary objectives included examining the relationship between initial AMERK titer levels and tumor burden. Methods: A retrospective cohort study across two institutions analyzed patients tested with AMERK within 90 days of MCC diagnosis. Regression models assessed the association of survival outcomes with serostatus, considering various factors. The relationship between AMERK titer and tumor burden indicators was evaluated using ANOVA. Significance testing was exploratory, without a fixed significance level. Results: Of 261 MCC patients tested, 49.4% were initially seropositive (titer ≥75). Multivariable analysis showed that seropositivity improved recurrence, event‐free, overall, and MCC‐specific survival rates. Strong associations were found between initial AMERK titer and clinical, tumor, and nodal stages, tumor size, and disease extent. Notably, improved survival with seropositivity was observed only in patients with localized disease at initial presentation. Conclusion: Circulating antibodies to MCPyV oncoproteins, as indicated by the AMERK test, are linked with better survival in MCC patients with localized disease at presentation. This could enhance patient risk profiling and treatment personalization. The study's retrospective nature and exploratory analysis are key limitations. Plain Language Summary: Merkel cell carcinoma (MCC) is a potentially aggressive skin cancer, and tools to predict patient outcomes are limited.A blood test called anti‐Merkel cell panel (AMERK), which checks for specific antibodies related to this cancer, might give us some clues.In this study, we looked at 261 MCC patients who took the AMERK test within 90 days of diagnosis.We found that patients with an initial positive AMERK result tended to have better outcomes, especially if their cancer was in the early stages.However, it is important to note that this study has limitations, including using retrospective data and exploratory analyses. In this retrospective study of 261 Merkel cell carcinoma (MCC) patients, the authors found that initial anti‐Merkel cell panel (AMERK) seropositivity was linked to improved recurrence, event‐free, overall, and MCC‐specific survival, particularly in patients with localized disease. This suggests the AMERK test could be key in risk stratification and tailoring management for MCC, despite the study's limitations due to its retrospective and exploratory nature. [ABSTRACT FROM AUTHOR]