Incorporation of plasma-based next-generation sequencing to improve guideline-concordant molecular testing in patients with newly diagnosed metastatic nonsquamous non-small cell lung cancer

14 Background: Current NCCN guidelines recommend comprehensive molecular profiling for all newly diagnosed patients with metastatic non-squamous NSCLC to enable the delivery of personalized medicine. We have previously demonstrated that incorporation of plasma based next-generation gene sequencing (NGS) improves detection of clinically actionable mutations in patients with advanced NSCLC (Aggarwal et al, JAMA Oncology, 2018). To increase rates of comprehensive molecular testing at our institution, we adapted our clinical practice to include concurrent use of plasma (P) and tissue (T) based NGS upon initial diagnosis. P NGS testing was performed using a commercial 74 gene assay. We analyzed the impact of this practice change on guideline concordant molecular testing at our institution. Methods: A retrospective cohort study of patients with newly diagnosed metastatic non-squamous NSCLC following the implementation of this practice change in 12/2018 was performed. Tiers of NCCN guideline concordant testing were defined, Tier 1: complete EGFR, ALK, BRAF, ROS1, MET, RET, NTRK testing, Tier 2: included above, but with incomplete NTRK testing, Tier 3: > 2 genes tested, Tier 4: single gene testing, Tier 5: no testing. Proportion of patients with comprehensive molecular testing by modality (T NGS vs. T+P NGS) were compared using one-sided Fisher’s exact test. Results: Between 01/2019, and 12/2019, 170 patients with newly diagnosed metastatic non-Sq NSCLC were treated at our institution. Overall, 98.2% (167/170) patients underwent molecular testing, Tier 1: n = 100 (59%), Tier 2: n = 39 (23%), Tier 3/4: n = 28 (16.5%), Tier 5: n = 3 (2%). Amongst these patients, 43.1% (72/167) were tested with T NGS alone, 8% (15/167) with P NGS alone, and 47.9% (80/167) with T+P NGS. A higher proportion of patients underwent comprehensive molecular testing (Tiers 1+2) using T+P NGS: 95.7% (79/80) compared to T alone: 62.5% (45/72), p < 0.0005. Prior to the initiation of first line treatment, 72.4% (123/170) patients underwent molecular testing, Tier 1: n = 73 (59%), Tier 2: n = 27 (22%) and Tier 3/4: n = 23 (18%). Amongst these, 39% (48/123) were tested with T NGS alone, 7% (9/123) with P NGS alone and 53.6% (66/123) with T+P NGS. A higher proportion of patients underwent comprehensive molecular testing (Tiers 1+2) using T+P NGS, 100% (66/66) compared to 52% (25/48) with T NGS alone (p < 0.0005). Conclusions: Incorporation of concurrent T+P NGS testing in treatment naïve metastatic non-Sq NSCLC significantly increased the proportion of patients undergoing guideline concordant molecular testing, including prior to initiation of first-line therapy at our institution. Concurrent T+P NGS should be adopted into institutional pathways and routine clinical practice.