Plasma Methylated DNA Markers for Melanoma Surveillance.

PURPOSE: Surveillance after primary melanoma treatment aims to detect early signs of low-volume systemic disease. The current standard of care, surveillance imaging, is costly and difficult to access. We therefore sought to develop methylated DNA markers (MDMs) as promising alternatives for disease surveillance. METHODS: We used reduced representation bisulfite sequencing (RRBS) to identify MDMs in DNA samples obtained from metastatic melanoma, benign nevi, and normal skin tissues. The identified MDMs underwent validation in an independent cohort of tissue and buffy coat DNA samples. Subsequently, we tested the validated MDMs in the plasma DNA of patients with metastatic melanoma undergoing surveillance with total body imaging and compared them with cancer-free controls. To estimate the overall predictive accuracy of the MDMs, we used random forest modeling with bootstrap cross-validation. RESULTS: Forty MDMs demonstrated discrimination between melanoma cases and controls consisting of benign nevi and normal skin. Nine MDMs passing biological validation in tissue were run on 77 plasma samples from individuals with a history of metastatic melanoma, 49 of whom had evidence of disease detected by imaging at the time of blood draw, and 100 cancer-free controls. The cross-validated sensitivity of the panel for imaging-positive disease was 80% with a specificity of 100% in cancer-free controls, resulting in an overall AUC of 0.88 (95% CI, 0.81 to 0.96). The survival estimates for patients with melanoma who tested positive for the panel at 6 months and 1 year were 67% and 56%, respectively, while those who tested negative had survival rates of 100% and 92%. CONCLUSION: MDMs identified by RRBS demonstrate a high degree of concordance with imaging results in the plasma of patients with metastatic melanoma. Further prospective studies in larger intended use cohorts are needed to confirm these findings.

Comparison of Tissue-Based Molecular Markers in Younger versus Older Patients with Colorectal Neoplasia.

BACKGROUND: Emerging colorectal cancer trends demonstrate increased incidence and mortality in younger populations, prompting consideration of average-risk colorectal cancer screening initiation at age 45 versus 50 years. However, screening test performance characteristics in adults 45-49 years have been minimally described. To inform the biologic rationale for multi-target stool DNA (mt-sDNA) screening in younger patients, we analyzed and compared tissue levels of methylation (BMP3, NDRG4) and mutation (KRAS) markers included in the FDA-approved, mt-sDNA assay (Cologuard; Exact Sciences Corporation). METHODS: Within 40-44, 45-49, and 50-64 year age groups, archived colorectal tissue specimens were identified for 211 sporadic colorectal cancer cases, 123 advanced precancerous lesions (APLs; adenomas >1 cm, high-grade dysplasia, ≥25% villous morphology, or sessile serrated polyp; 45-49 and 50-64 age groups only), and 204 histologically normal controls. Following DNA extraction, KRAS, BMP3, and NDRG4 were quantified using QuARTS assays, relative to ACTB (reference gene). RESULTS: None of the molecular marker concentrations were significantly associated with age (P > 0.05 for all comparisons), with the exception of NDRG4 concentration in APL samples (higher in older vs. younger cases; P = 0.008). However, NDRG4 levels were also statistically higher in APL case versus normal control samples in both the 45-49 (P < 0.0001) and 50-64 (P < 0.0001) year age groups. CONCLUSIONS: Overall, these findings support the potential for earlier onset of average-risk colorectal cancer screening with the mt-sDNA assay. IMPACT: These novel data address an identified knowledge gap and strengthen the biologic basis for earlier-onset, average-risk screening with the mt-sDNA assay.