ctDNA Outperforms MCPyV Antibody Testing for Merkel Cell Carcinoma Surveillance

Circulating tumor DNA (ctDNA) may provide a more accurate method for detecting recurrence of Merkel cell carcinoma (MCC) than the currently available Merkel cell polyomavirus (MCPyV) oncoprotein antibody test, according to results from a multicenter US cohort study.

Researchers evaluated 169 patients with stage I-IV MCC across Stanford University, Dana-Farber Brigham Cancer Center, and the University of Washington between April 2020 and March 2024. All participants were clinically disease-free at enrollment, had detectable MCPyV antibodies at diagnosis, and underwent serial paired ctDNA and antibody testing during routine surveillance.

ctDNA Shows Superior Accuracy for Detecting MCC Recurrence

During a median follow-up of 483 days, investigators analyzed 703 paired blood tests and documented 36 clinical recurrences among 32 patients. Compared with MCPyV antibody testing, ctDNA demonstrated superior performance across multiple surveillance metrics.

At 365 days, ctDNA achieved a significantly higher positive predictive value than antibody testing (73% vs 52%; P = 0.02). It also demonstrated a higher negative predictive value at 90 days (99% vs 97%; P = 0.001), indicating greater confidence in ruling out disease recurrence after a negative result.

Positive ctDNA results were associated with a substantially greater risk of recurrence than rising antibody titers (hazard ratio [HR], 47.9 vs 7.3; HR ratio, 6.6; P < 0.001). Notably, using both biomarkers together identified only one additional recurrence beyond ctDNA testing alone.

"Results of this study suggest that ctDNA outperforms antibody testing for detecting recurrent Merkel cell carcinoma," the authors wrote.

Source

Thankuria M, et al. JAMA Dermatology. 2026. Doi:10.1001/jamadermatol.2026.2153