In a study reported in the Journal of Clinical Oncology, Akaike et al found that detection of circulating tumor DNA (ctDNA) was associated with an increased risk of recurrence in patients with Merkel cell carcinoma.
Study Details
In the study, a tumor-informed ctDNA assay was used in 319 patients from five U.S. centers, including a discovery cohort (two centers, n = 167) and a validation cohort (three centers, n = 152).
Key Findings
For detecting disease at enrollment, the ctDNA test had sensitivities of 95% (95% confidence interval [CI] = 87%–99%) in the discovery cohort and 94% (95% CI = 85%–98%) in the validation cohort. The test had specificities of 90% (95% CI = 82%–95%) and 86% (95% CI = 77%–93%), respectively.
Positive vs negative ctDNA testing during surveillance was associated with an increased risk of recurrence, with hazard ratios (HRs) of 6.8 (95% CI = 2.9–16) in the discovery cohort and 20 (95% CI = 8.3–50) in the validation cohort. The positive predictive value for clinical recurrence at 1 year after a positive ctDNA test was 69% (95% CI = 32%–91%) in the discovery cohort and 94% (95% CI = 71%–100%) in the validation cohort. The negative predictive value at 135 days after a negative ctDNA test was 94% (95% CI = 90%–97%) in the discovery cohort and 93% (95% CI = 89%–97%) in the validation cohort.
Positive ctDNA testing within 4 months after treatment was associated with higher rates of recurrence, with 1-year rates of 74% vs 21% (adjusted HR = 7.4, 95% CI = 2.7–20).
The investigators concluded: “ctDNA testing exhibited high prognostic accuracy in detecting Merkel cell carcinoma recurrence, suggesting its potential to reduce frequent surveillance imaging. ctDNA also identifies high-risk patients who need more frequent imaging and may be best suited for adjuvant therapy trials.”
Lisa C. Zaba, MD, PhD, of Stanford University School of Medicine, is the corresponding author of the Journal of Clinical Oncology article.
Disclosure: The study was supported by the Kuni Foundation Discovery Grant for Cancer Research, National Cancer Institute, and others. For full disclosures of the study authors, visit ascopubs.org.
