A specific type of plasma genotyping identified epidermal growth factor receptor (EGFR) and KRAS mutations quickly and accurately in a study involving 180 individuals.
Participants had either newly-diagnosed advanced nonsquamous non–small-cell lung cancer or resistance to an EGFR kinase inhibitor. They underwent plasma droplet digital PCR (ddPCR) for EGFR exon 19 del, L858R, T790M, and/or KRAS G12X. They also had tissue biopsy for reference. Among the results:
• Plasma ddPCR was turned around in a median of 3 days.
• Tissue genotyping turnaround time took a median of 12 days for patients with newly diagnosed cancer, and 27 days for those with acquired resistance.
• Plasma ddPCR had a positive predictive value of 100% for EGFR 19 del, L858R, and KRAS.
• Positive predictive value was 79% for T790M.
• Plasma ddPCR had 82% specificity for EGFR 19 del, 74% for L858R, 77% for T790M, and 64% for KRAS.
The authors concluded that ddPCR’s high specificity can help avoid repeat biopsies.
Citation: Sacher A, Paweletz C, Dahlberg S, et al. Prospective validation of rapid plasma genotyping for the detection of EGFR and KRAS mutations in advanced lung cancer. [Published online ahead of print April 7, 2016]. JAMA Oncol. doi:10.1001/jamaoncol.2016.0173.