An ultrasensitive method for quantitating circulating tumor DNA with broad patient coverage

Aaron Newman and his colleagues introduce a next-generation sequencing–based approach for the cost-effective detection and quantitation of tumor-derived circulating DNA in both early- and advanced-stage tumors and with high levels of sensitivity and specificity. CAPP-Seq (cancer personalized profiling by deep sequencing) can simultaneously detect multiple mutations and mutation types, including rearrangements. Here, utility is demonstrated for non–small-cell lung cancer. Circulating tumor DNA (ctDNA) is a promising biomarker for noninvasive assessment of cancer burden, but existing ctDNA detection methods have insufficient sensitivity or patient coverage for broad clinical applicability. Here we introduce cancer personalized profiling by deep sequencing (CAPP-Seq), an economical and ultrasensitive method for quantifying ctDNA. We implemented CAPP-Seq for non–small-cell lung cancer (NSCLC) with a design covering multiple classes of somatic alterations that identified mutations in >95% of tumors. We detected ctDNA in 100% of patients with stage II–IV NSCLC and in 50% of patients with stage I, with 96% specificity for mutant allele fractions down to ∼0.02%. Levels of ctDNA were highly correlated with tumor volume and distinguished between residual disease and treatment-related imaging changes, and measurement of ctDNA levels allowed for earlier response assessment than radiographic approaches. Finally, we evaluated biopsy-free tumor screening and genotyping with CAPP-Seq. We envision that CAPP-Seq could be routinely applied clinically to detect and monitor diverse malignancies, thus facilitating personalized cancer therapy.