Real-world outcomes among patients with advanced EGFRm NSCLC previously treated with osimertinib and platinum-based chemotherapy.

396 Background: For patients with advanced EGFR-mutant non-small cell lung cancer (EGFRm aNSCLC) progressing after osimertinib (OSI) and platinum-based chemotherapy (PBC) no uniformly accepted standard of care exists. The study was to provide updated results with a refreshed dataset for a previous study describing clinical outcomes of treatment regimens initiated after OSI and PBC in real-world patients with similar baseline characteristics to those in HERTHENA-Lung01 (HL-01), a multinational single-arm phase II trial evaluating the safety and efficacy of patritumab deruxtecan 1 . Methods: This study analyzed data from the US nationwide Flatiron Health electronic health record–derived aNSCLC de-identified database from approximately 280 US cancer clinics (~800 sites of care). Adult patients with an aNSCLC diagnosis (after 01 January 2011) and prior treatment with OSI and PBC, who initiated a subsequent line of therapy (index LOT) before 01 August 2022 were included in the study. Patients were chosen to closely match the HL-01 eligibility criteria (documented exon 19 deletion or L858R mutation; Eastern Cooperative Oncology Group Performance Status of 0 or 1; and absence of relevant comorbidities at index date). To further balance patient characteristics, the sample was propensity-score (PS) weighted based on nine covariates. Real-world overall survival (rwOS), progression-free survival (rwPFS) and overall response (rwORR, defined as partial or complete response with ≥2 assessments ≥28 days apart) were assessed from the start of the index LOT with corresponding 95% confidence intervals (CI). Results: 179 patients in the database fulfilled the eligibility criteria, increasing the sample size by 42% compared to the previous study 1 . Median age of the unweighted sample at index was 68 years, 65.9% of patients were female, 40.2% had a history of smoking and 26.3% received more than 3 LOTs prior to the index LOT. In the PS-weighted cohort (standard mean difference of all covariates was ≤0.127) the median rwOS was 9.1 months (95% CI: 7.3 – 11.3) and median rwPFS was 3.5 months (95% CI: 2.7 – 4.6). For a subsample of 75 patients with qualifying response assessments, rwORR was 12.7% (95% CI: 4.8 – 25.7). Conclusions: These observations in patients with EGFRm NSCLC after OSI and PBC demonstrate a limited clinical benefit with currently available therapies. The results are consistent with the previously published study and increase precision of the outcome estimates 1 . They highlight the high unmet need and provide further context on clinical outcomes of HL-01 trial results. 1 Patel et al. Clinical Outcomes of Real-World Treatment for Metastatic EGFRm NSCLC after Osimertinib and Platinum-Based Chemotherapy. 2023 Sep 9-12 Singapore. P2.31.