In a significant percentage of advanced NSCLC patients, tumor tissue is unavailable or insufficient for genetic analyses. A prospective study was designed to evaluate use of circulating free DNA (cfDNA) purified from blood of patients with advanced NSCLC to detect mutations of EGFR. Patients treated with EGFR inhibitors based on mutations detected by cfDNA were found to have an objective response rate of 72% and a median progression-free survival of 11 months.
The characteristics and clinical outcomes to TKI treatment of the EGFR mutated patients identified are undistinguishable from those positive in tumor. These data suggest that testing for EGFR mutations in blood is feasible, with clinical outcomes similar to those based on tumor tissue testing. Large scale EGFR testing in the blood of unselected advanced NSCLC patients is feasible and can be used to select patients for targeted therapy when testing cannot be done in tissue.
