Realizing the potential of plasma genotyping in an age of genotype-directed therapies.

The identification of oncogenic driver mutations in cancer has led to the rapid rise of genotype-directed treatments such as EGFR and BRAF kinase inhibitors. Standard tumor biopsy remains a cumbersome and morbid procedure for patients, leading to a growing interest in noninvasive plasma genotyping approaches. Circulating tumor cells are of interest; however, the processing of specimens is complicated and time consuming. By comparison, cell-free DNA (cfDNA) genotyping has the potential to be convenient and relatively simple to process in a short time period. Several technologies are under development for cfDNA analysis, such as allele-specific polymerase chain reaction (PCR), coamplification at Lower Denaturation temperatures (COLD) PCR, emulsion PCR, and massively parallel sequencing. Broad clinical validity will need to be established for different assays, and clinical utility will need to be evaluated within prospective trials to determine which assays will best predict the efficacy of therapy and patient outcomes. In addition, assay standardization will be critical prior to widespread use in routine clinical practice. The Cell Free DNA Working Group, under the sponsorship of Transgenomic, was convened to evaluate the molecular assays in development and provide recommendations for application and interpretation of these tests in the context of future clinical research. The consensus commentary of the Cell Free DNA Working Group for the use of cfDNA plasma genotyping assays is presented here, including future steps in the development of these technologies.