Abstract

As a high-performance solution for longitudinal monitoring of patients being treated for metastatic cancer, we developed and a single-color digital PCR (dPCR) assay that detects and quantifies specific cancer mutations present in circulating tumor DNA (ctDNA). This customizable assay has a high sensitivity of detection. One can detect a mutation allelic fraction of 0.1%, equivalent to three mutation-bearing DNA molecules among 3,000 genome equivalents. The objective of this study was to validate the use of personalized dPCR mutation assays to monitor patients with metastatic cancer. We compared our digital PCR results to serum biomarkers indicating disease progression or response. Patients had metastatic colorectal, biliary, breast, lung and melanoma cancers. Mutations occurred in essential cancer drivers such as BRAF, KRAS and PIK3CA. We monitored patients over multiple cycles of treatment up to a year. All patients had detectable ctDNA mutations. Our results correlated with serum markers of metastatic cancer burden including CEA, CA-19-9, and CA-15-3, and qualitatively corresponding to imaging studies. We observed corresponding trends among these patients receiving active treatment with chemotherapy or targeted agents. For example, in one patient under active treatment, we detected increasing quantities of ctDNA molecules over time, indicating recurrence of tumor. Our study demonstrates that personalized digital PCR enables longitudinal monitoring of patients with metastatic cancer and maybe a useful indicator for treatment response.

View details for DOI 10.1016/j.jmoldx.2019.10.008

View details for PubMedID 31837432