The study evaluated the Signatera test against the Merkel cell polyomavirus antibody test (AMERK), finding Signatera to be a significantly stronger predictor of recurrence that also detected relapse earlier.

MCC is a rare but aggressive skin cancer that recurs in approximately 40% of patients.1 Despite its severity, clinicians have lacked a reliable, universal biomarker to guide surveillance. The AMERK test has been a widely used monitoring tool, but its utility is limited: it can only be used in the roughly 50% of MCC patients whose tumors are virus-positive, and its accuracy diminishes after immunotherapy exposure or multiple recurrences.2-3 Signatera’s clinical validation has been published across all MCC patients, irrespective of viral status, leading to inclusion in NCCN Guidelines as a recommendation for surveillance monitoring.

This published study is a retrospective analysis of a prospective, multicenter, head-to-head comparison of Signatera and AMERK testing in 169 patients with MCC. Key findings include:

• Superior predictive power: The Signatera test was a significantly stronger predictor of recurrence than AMERK (HR difference = 6.6; p < 0.001), with higher hazard ratios, higher positive predictive value (PPV), and higher negative predictive value (NPV).
• Higher Sensitivity: Signatera detected recurrence more frequently than AMERK with a sensitivity of 90% vs 55%, respectively.
• Longer Lead Time: In patients where recurrence was detected by both tests, Signatera detected recurrence earlier than AMERK with a median lead time of 5.1 months vs. 2.1 months, respectively.