Molecular counting enables accurate and precise quantification of methylated ctDNA for tumor-naive cancer therapy response monitoring.

Personalized cancer treatment can significantly extend survival and improve quality of life for many patients, but accurate and real-time therapy response monitoring remains challenging. To overcome logistical and technical challenges associated with therapy response monitoring via imaging scans or assays that track the variant allele fraction (VAF) of somatic mutations in circulating tumor DNA (ctDNA), we developed a tumor-naive liquid biopsy assay that leverages Quantitative Counting Template (QCT) technology to accurately and precisely quantify methylated ctDNA (Northstar Response™). The assay achieves < 10% coefficient of variation at 1% tumor fraction, which is 2 × lower than tumor-naive, targeted-panel approaches using VAF.

Brief Report: Methylation-Based ctDNA Serial Monitoring Correlates With Immunotherapy Response in NSCLC.

Purpose: Circulating tumor DNA (ctDNA) can reflect the genetic and epigenetic composition of malignancies and can serve as a noninvasive biomarker for cancer diagnostics and monitoring. This study aimed to evaluate the utility of a methylation-based ctDNA assay as a predictive tool in non-small cell lung cancer (NSCLC) anti-PD1 based immunotherapy monitoring.

Methods: We evaluated a cohort of 20 patients with NSCLC treated with anti-PD1 based immunotherapy that had both baseline and follow-up blood draws as well as outcome data available.