The utility of liquid biopsies for management of stage IV non-small cell lung cancer (NSCLC) in an academic community medical center.

Abstract

e20577 Background: The management of stage 4 non-squamous non-small cell lung cancer (NSCLC) relies heavily on the use of tumor genotyping that allows for the preferential use of targeted therapies as first-line treatment to eligible patients. Recently, the “liquid biopsy”, a non-invasive genomic analysis of circulating tumor DNA, has been deemed a suitable complementary method to identify actionable mutations and guide therapy in NSCLC patients. At our community-based academic medical system in suburban Philadelphia, liquid biopsies began to be used more regularly for these patients in 2018. All patients in the study received tissue biopsies with molecular testing. Our study compared patients who also underwent liquid biopsy with patients who did not, in order to determine whether performance of this biopsy affected their treatment. Methods: This retrospective cohort study used a bank of Main Line Health patients diagnosed with Stage 4 non-squamous NSCLC from 2014-2020. Chart review was used to extract variables from these patients regarding dates of tissue biopsies and treatments, information on liquid biopsies, and demographic information. The primary objective was to compare the rate of detection of actionable mutations in the liquid biopsy vs. non-liquid biopsy cohorts. A secondary objective was to assess the time interval between the identification of a potential lung cancer by imaging and the initiation of first line therapy. Results: 152 patients met inclusion criteria and of these 68 patients underwent liquid biopsy testing and 84 patients did not. Of the 68 patients who underwent liquid biopsy testing, 34 patients (50% patients) did not have sufficient tissue on their tissue biopsy for a molecular diagnosis. Of these 34 patients, 15 patients (44%) had an actionable mutation detected with liquid biopsy. Thus, 28 patients (41%) of the liquid biopsy group had actionable mutations detected. In comparison, only 18 patients (21%) in the cohort without liquid biopsy testing had actionable mutations detected. The initiation of first line treatment occurred sooner for the group undergoing liquid biopsies, an average of 48.3 days (median 40.5 days, range 13-317) compared to 72.7 days (median 50.5 days, range 14-534), p = 0.012 by two-tailed T-test. Conclusions: In our community academic medical center, patients with stage IV non-squamous, NSCLC who underwent a liquid biopsy as part of their initial diagnostic workup had a higher rate of detection of actionable mutations and initiated first line therapy sooner than patients who received only tissue-based molecular diagnostic testing.