DNA Enrichment Increases Usefulness of Liquid Biopsy Technology

DNA enrichment technology was a critical tool used in a study that detected genetic variations in circulating tumor cells (CTCs) in blood samples from non-small-cell lung cancer patients.

Investigators from four major American cancer centers—Massachusetts General Hospital (Boston, USA), Harvard Medical School (Boston, MA, USA), the University of Texas MD Anderson Cancer Center (Houston, USA), and Weill Cornell Medical College (New York, NY, USA)—participating in the "Stand Up to Cancer" program, attempted to identify the epidermal growth factor receptor (EGFR) T790M mutation, which is associated with resistance to certain cancer drug treatments.

To this end, the investigators performed an exploratory analysis of 40 patients with EGFR-mutant tumors that continued to progress despite EGFR TKI (tyrosine kinase inhibitor) therapy. They compared the T790M genotype from tumor biopsies with analysis of simultaneously collected circulating tumor cells (CTC) and circulating tumor DNA (ctDNA). The T790M mutation from the CTC samples was enriched using the EKF Molecular Diagnostics (Cardiff, United Kingdom) PointMan EGFR T790M DNA enrichment kit to enhance the sensitivity of the test procedure allowing accurate genotyping to take place.

Results indicated that T790M genotypes were successfully obtained in 30 (75%) tumor biopsies, 28 (70%) CTC samples, and 32 (80%) ctDNA samples. The resistance-associated mutation was detected in 47%–50% of patients using each of the genotyping assays, with concordance among them ranging from 57%–74%. While CTC- and ctDNA-based genotyping were each unsuccessful in 20%–30% of cases, the two assays together enabled genotyping in all patients with an available blood sample, and the investigators identified the T790M mutation in 14 (35%) patients in whom the concurrent biopsy was negative or indeterminate.

Julian Baines, CEO of EKF Diagnostics said, “This is the first published scientific paper to feature PointMan and, importantly, the authors are primarily from four US cancer centers that are instrumental in the "Stand Up to Cancer" program. These results show that liquid biopsy is well on the way to becoming a realistic diagnostic alternative to tissue biopsy, particularly when several samples need to be taken during the treatment period. Importantly this study shows that PointMan enrichment technology could become an essential part of routine blood tests for cancer diagnosis and treatment monitoring.”

The study was published in the October 7, 2015, online edition of the journal Clinical Cancer Research.

Related Links:
Massachusetts General Hospital
Harvard Medical School
EKF Molecular Diagnostics