40P Real-world treatment patterns and clinical outcomes following first-line osimertinib (osi) in patients (pts) with EGFR-mutant NSCLC in China

Background: Osi is standard of care for treatment-nave EGFR-mutant advanced nonsmall cell lung cancer (NSCLC).However, the optimal treatment strategy after progression on osi remains unclear.This retrospective study described real-world disease characteristics, treatment patterns and clinical outcomes in post 1L osi progression setting to better understand variability in this scenario.Methods: Eligible pts included adults (18 year) with EGFRm advanced NSCLC who progressed on 1L osi between Jan 2019 and Dec 2023, and for whom 2L treatment data were available from nine centers in China.Primary endpoint was treatment patterns.Secondary endpoints included real-world progression free survival (rwPFS) and overall survival (OS) of different treatment regimens and safety.Data cutoff date was Nov 30, 2024.Results: A total of 394 pts were enrolled in the study.The median age was 62 years (range, 55-69), 55% pts were female, 87% had an ECOG PS of 0-1 and 40% had brain metastases.Molecular biomarkers testing was performed for 51% (201/394) pts, with MET amplification (20%, 41/201) identified as predominant resistance mechanism.2L treatment regimens were varied: TKI-based (56%, 220/394), chemo-based (31%, 122/394), IO-based (12%, 47/394) and other therapy (1%, 5/394), with median rwPFS 7.2 (95% CI: 5.9-8.2),6.8 (95% CI: 5.4-8.0),5.2 (95% CI: 3.9-8.6),6.5 (95% CI:4.5-11.8)months(mo) and median OS (mOS) ) mo, respectively.Among them, 12.7% (50/394) pts received 3G TKI plus chemotherapy (CTx) and 12.2% (48/394) received CTx alone.3G TKI plus CTx showed a numerically longer median rwPFS (6.4 vs. 4.4 mo) and mOS (17.3 vs. 11.9 mo) than CTx-alone.No new safety signals were observed in 2L treatment regimens. Conclusions:To our knowledge, this is the largest real-world study in China to understand 2L treatment patterns and clinical outcomes in post 1L osi progression setting.TKI-based therapy was the most common subsequent treatment patterns in real-world setting.3G TKI plus CTx may be an effective treatment strategy, further prospective validation is still required.Clinical trial identification: ChiCTR2500115193.