Outcomes with liquid biopsy to determine the EGFR mutation status in poor performance status, biopsy-ineligible, advanced NSCLC patients

Abstract

Background: Outcomes based on liquid biopsy in poor performance, older, biopsy-ineligible advanced non-small cell lung cancer (NSCLC) patients are unknown. Aim: The aim of the study was to evaluate the outcomes of patients treated on the basis of liquid biopsy to determine the epidermal growth factor receptor (EGFR) status. Objectives: The objective was to evaluate the progression-free survival (PFS) and overall survival (OS) of patients treated based on EGFR mutation status, determined on a liquid biopsy. Materials and Methods: This was a retrospective audit of prospectively maintained database of patients who underwent liquid biopsy EGFR mutation testing between July 2017 and January 2019 and received treatment based on that report. The primary end point was PFS defined as duration between the date of sample collection and disease progression or death, whereas OS was calculated as the interval between the date of sample collection and death. Kaplan–Meier survival was used for the above two end points. Results: Out of 28 patients, 11 (39%) were EGFR mutation positive, and 17 (61%) were EGFR mutation negative. The median age was 62 years, with 15 out of the 28 being females (54%). Nine (82%) and 13 (76%) patients had performance status (PS) 2 or 3 in the EGFR mutation-positive and EGFR mutation-negative cohorts, respectively. In the EGFR mutation-positive cohort, 4 (36%) were exon 19, 6 (54%) were exon 21, and 1 (9%) was T790M positive. After receiving tyrosine kinase inhibitors or physician's choice of chemotherapy in EGFR mutation-positive and negative cohorts, the response rates were 63% and 12%, respectively. The median follow-up was 14 months (range: 10–17 months). The median PFS was 8 months versus 2 months (P = 0.002), whereas the median OS was 17 months versus 5 months (P = 0.004) in the EGFR mutation-positive and EGFR mutation-negative cohorts, respectively. Conclusion: In patients with advanced NSCLC in whom a tissue biopsy is not feasible, especially in older, poor PS patients, treatment based on the results of liquid biopsy gives comparable outcomes to those of a tissue-based biopsy.