Development of a Highly Sensitive Multicancer, Targeted, Cell-Free DNA Epigenomic Assay for Integrated Screening of Lung and Colorectal Cancer.

3542 Background: Cancer screening in asymptomatic individuals who meet guideline criteria has yielded reductions in cancer death rates. However, adherence to screening guidelines remains below targets set forth by leading health-care organizations. A blood-based multi-cancer screening assay with clinically meaningful sensitivity and specificity, in cancer types where early detection and intervention can save lives, that is integrated with existing clinical pathways may increase access to and adherence with guideline recommendations, ensuring more individuals benefit from these proven interventions. We evaluated the performance of a blood-based multi-cancer screening assay that interrogates cell-free DNA (cfDNA) methylation signatures for cancer detection and tissue of origin prediction in a set of tumor types where cancer screening can save lives. Methods: Whole blood from 1,607 individuals with and 3,298 individuals without cancer was obtained from multiple unique cohorts. Plasma-derived cfDNA was profiled using a custom assay that enriches fragments with dense CpG methylation and further depletes uninformative background molecules containing unmethylated CpGs. We utilized a broad genomic panel (16 Mb) targeting regions with low rates of methylation in individuals without cancer. The panel captures tumor-associated molecules and allows for high sensitivity of detection at low sequencing costs. A cross-validated analysis was used to estimate the performance of the predictive model upon the sample set. Classification thresholds corresponding to 90%, 95%, and 98% specificities were established using samples from individuals without a cancer diagnosis. Results: At 90% specificity, overall sensitivity for lung cancer detection was 92.1% (95% CI: 80-100%; 90.2% in Stage I/II disease (N = 82) and 93.1% in Stage III/IV disease (N = 159)) and 93.1% (CI: 88-98%) for CRC detection (92% in Stage I/II disease (N = 743) and 94.5% in Stage III/IV disease (N = 623)). Tissue of origin prediction evaluated at 98% specificity yielded accurate identification in 99% of CRC and 98% of lung cancers. Lung cancer histology was known for approximately 74% of the cohort. Across Stage I – IV cancers, at 90% specificity, sensitivity was 97.3% in lung squamous cancer (N = 73) and 86.8% in lung adenocarcinoma (N = 106). At 95% and 98% specificity thresholds, overall sensitivity was 86.3% (CI: 75-98%) and 66.4% (CI: 56-77%) for lung cancer and 85.7% (CI:81-91%) and 71.6% (CI: 67-76%) for CRC, respectively. Conclusions: This blood-based multi-cancer screening assay yields clinically meaningful sensitivity and specificity for early-stage cancers. This assay is undergoing further development to expand detection capabilities to additional cancer types where screening can save lives. Clinical evaluation in registrational screening trials is ongoing (SHIELD; NCT05117840).