A commercially available liquid biopsy test can predict survival outcomes up to 54 months after initial presentation in patients with stage III melanoma, according to a report in Clinical Cancer Research.

The study is the first to show that “a simple blood-based test based on semiautomated, melanoma-specific enrichment, independently predicted relapse for node-positive melanoma patients,” according to the investigators, led by Anthony Lucci, MD, a professor in the Department of Breast Surgical Oncology at the University of Texas MD Anderson Cancer Center, in Houston.

“This is important since this technology is standardized, and can be easily assimilated to other centers to provide risk stratification for a group of patients where there are no biomarkers currently available to guide adjuvant treatment,” they noted.

Although the CellSearch CTC Test (Menarini Silicon Biosystems) has been studied in determining prognosis in patients with melanoma, those trials were limited to stage IV patients, according to Dr. Lucci and his co-investigators.

 To determine whether baseline circulating tumor cells (CTCs) can predict relapse in patients with stage III melanoma, they administered the assay in 243 patients presenting with stage III melanoma at their institution between 2012 and 2017 (Clin Cancer Res 2020;26[8]:1886-1895). None of the patients had mucosal or uveal melanoma or metastatic disease at the time of presentation. Patients were a mean of 57 years of age at study outset and were followed for a median of 17 months (range, 1-64 months). Forty-five patients (19%) had stage IIIA disease, 67 (28%) had stage IIIB, 118 (49%) had stage IIIC, and 13 (5%) had stage IIID.
Dr. Lucci’s team detected at least one baseline CTC in 90 of the patients (37%).

Compared with those without CTCs at baseline, the likelihood of six-month relapse-free survival was over 3.5 times lower among those with at least one baseline CTC (hazard ratio (HR), 3.62; 95% CI, 1.78-7.36; P<0.0001), and the likelihood of 54-month relapse-free survival also was lower in this group (HR, 2.25; 95% CI, 1.25-4.06; P=0.006). These associations persisted after controlling for factors such as nodal stage, sex, age, Breslow thickness, ulceration and lymphovascular invasion.

The researchers said their findings point to the utility of liquid biopsy in identifying patients with stage III melanoma who would derive the greatest benefit from adjuvant systemic therapy.

“In current practice there is no clear consensus regarding adjuvant systemic therapy for patients with node-positive melanoma,” the investigators noted. “Information on circulating tumor cells and early relapse provides a basis for future clinical trials of adjuvant treatments and enhanced imaging in those patients at the highest-risk for relapse.”

—David Wild