TOPLINE:

In a prospective study of patients with stages I-III Merkel cell carcinoma (MCC), seropositivity for rising polyomavirus oncoprotein antibody titers conferred a 58% risk for recurrence at 12 months, whereas falling or negative titers were associated with a 99.3% probability of remaining recurrence free at 3 months.

METHODOLOGY:

• Researchers conducted a prospective cohort study of 503 patients (median age at diagnosis, 70 years; 40% women) with stages I-III MCC who underwent baseline Merkel cell polyomavirus (MCPyV) oncoprotein antibody testing within 90 days of diagnosis, between June 2008 and October 2020.
• Overall, 49% of patients were seropositive (initial titers of 75 or greater standard titer units [STU] pretreatment).
• Antibody titers were measured every 3-6 months and classified as rising (≥ 30% increase; n = 62), falling or negative (≥ 30% decrease or < 75 STU; n = 877), stable (any titer after the first one that did not meet criteria for rising, falling, and negative; n = 317), or deferred (first posttreatment titer that did not meet rising or falling criteria; n = 146).
• The median follow-up duration was 4.2 years.

TAKEAWAY:

• The 5-year risk for recurrence was higher among seronegative patients than among seropositive patients (45% vs 30%; adjusted hazard ratio, 1.63; P = .002). Among seropositive patients without recurrence, titers decreased by a median of 50% every 3 months, reaching < 75 STU by a median of 13 months after diagnosis.
• After a falling or negative titer, the likelihood of remaining recurrence free was 99.3% at 3 months and 98.8% over 6 months.
• A single rising titer predicted a 36% risk for recurrence at 3 months, which increased to 58% by 12 months. The median time from the first rising titer to recurrence was 3.7 months. Of the 39 patients with at least one rising titer, 14 remained recurrence free for 1 year or longer, and none died of MCC at a median follow-up of 4.9 years.
• Stable titers carried a low or intermediate risk for recurrence (3-month risk, 2.2%), but risk varied sharply based on prior titer trends: A stable titer after an increase carried a 24% risk for recurrence at 3 months, whereas stable titers after a falling or previously stable titer had minimal risk (0% and 1%, respectively).

IN PRACTICE:

“For patients who are seropositive, MCPyV oncoprotein antibody titers can offer meaningful reassurance or early detection of recurrence,” the authors of the study wrote. “Identifying disease at an earlier, lower burden stage may improve outcomes through timely treatment initiation,” they added, noting that “patients who are seronegative — who cannot be monitored by this test — may benefit from ctDNA [circulating tumor DNA] surveillance or more frequent imaging when ctDNA is unavailable.”

SOURCE:

The study was led by Lindsay Gunnell, MD, Department of Dermatology, University of Washington, Seattle, and was published online on September 10 in JAMA Dermatology.

LIMITATIONS:

The study’s observational design led to inconsistent timing of blood draws and imaging, introduced potential surveillance bias, and did not allow for causal conclusions.

DISCLOSURES:

The study was supported by the National Institutes of Health/National Cancer Institute, the Kelsey Dickson Team Science Courage Research Award, and the Friends and Family of Nancy Haeseker fund. Two authors reported receiving grants, support, and consulting fees from GE HealthCare, Incyte Corp Research, Bristol Myers Squibb, EMD Serono, Merck, and Sanofi/Regeneron outside the submitted work. Additional disclosures are noted in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.