Abstract 933: Real world treatment patterns and outcomes in patients with advanced non-small cell lung cancer (aNSCLC) post-EGFR tyrosine kinase inhibitor (TKI) therapy
Authors: Ebot Ericka , He Jie , Fabrizio David , Altomare Ivy , Jain Neha , Daniel Davey , Stricker Thomas , Arrowsmith Edward 
Published: April 2023

Abstract
Background:Third generation EGFR TKIs have emerged as a first line treatment of choice for aNSCLC patients with qualifying EGFR mutations due to high and durable response rates; however most patients will progress on therapy and may receive further treatment. Second line (2L) options include other EGFR TKIs, chemotherapy (C) and chemoimmunotherapy (C-IO). An optimal treatment strategy and utility of biomarkers in this 2L setting remain uncharacterized. In this study, we aim to describe the real-world treatment patterns and outcomes of patients with aNSCLC after treatment with first line (1L) EGFR TKIs to elucidate the potential for biomarker-guided approaches.
Methods:We selected patients with non-squamous aNSCLC treated with 1L EGFR TKIs on or after April 1, 2018 (based on 1L approval of osimertinib) within the US-based de-identified Flatiron Health-Foundation Medicine (FMI) real world clinico-genomic database. Real world overall survival (rwOS) and progression free survival (rwPFS) curves and estimates of median survival time were generated using the Kaplan-Meier method. PD-L1 and tumor mutational burden (TMB) were summarized overall and by 2L treatment regimen.
Results:Among 428 patients who received 1L EGFR TKI treatment, 386 (90%) received osimertinib, 30 (7%) received afatinib and 11 (3%) received erlotinib. For patients with known 2L treatment information (n=139, 32%) most received EGFR TKI alone (n=43, 31%), followed by C-IO (n=38, 27%), and C alone (n=14, 10%). Median rwOS following 2L treatment with EGFR TKI, C-IO, and C was 21.0 (95% CI 17.4-28.7) months, 9.9 (95% CI 7.7-19.8) months, and 17.4 (95% CI 4.3-NA) months respectively. Median rwPFS for the EGFR-TKI, C-IO, and C cohorts was 5.1 (95% CI 3.4-12.5) months, 5.5 (95% CI 3.3-7.0) months, and 3.5 (95% CI 1.9-NA) months. 416 (97%) of 428 patients harbored an EGFR mutation detected by FoundationOne®CDx, including 361 (84%) patients with at least one EGFR mutation in NCCN Guidelines. Among patients with available PD-L1 status (n=254, 59%), PD-L1 positivity (≥1% tumor proportion score) was more common among patients who received 2L C-IO (88%) compared to patients overall (59%). 30 (7%) of 428 patients had high TMB (≥10 mut/Mb); prevalence of high TMB was similar regardless of 2L therapy choice.
Conclusions:This real-world data analysis confirmed that among patients with aNSCLC treated with EGFR TKIs, the vast majority received 1L osimertinib. Among 2L treatment options, additional EGFR TKI use was the most common and patients in this cohort had robust outcomes, with a median rwOS of 21 mos. Further analyses will describe the clinical characteristics of patients receiving different 2L treatment strategies and evaluate the association of PD-L1 status and select EGFR mutations with outcomes across therapeutic classes.
Citation Format: Ericka Ebot, Jie He, David Fabrizio, Ivy Altomare, Neha Jain, Davey Daniel, Thomas Stricker, Edward Arrowsmith. Real world treatment patterns and outcomes in patients with advanced non-small cell lung cancer (aNSCLC) post-EGFR tyrosine kinase inhibitor (TKI) therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 933.