Real-world outcomes of osimertinib in Peruvian patients with advanced NSCLC with EGFR T790M-positive: A multi-institutional experience.

e20605 Background: Osimertinib is the standard of care for advanced NSCLC patients with EGFR T790M-positive whose disease has progressed to EGFR TKI therapy, however, the knowledge on the real benefit of these therapies in the Latin American setting remains unclear due the lack of access in the most countries. The aim of this study is to evaluate the outcomes of Osimertinib as sencond line treatment of advanced NSCLC patients with EGFR T790M-positive in a real-world Peruvian setting. Methods: This is a retrospective study of advanced NSCLC patients with EGFR T790M-positive treated with osimertinib at seven Peruvian institutions between July 2018 and May 2023. Outcomes were objective response rate (ORR), progression-free survival (PFS), overall survival (OS) and OS from the start of first-line treatment to death. Results: We analyzed 41 T790M-positive patients with a median age of 60 years (range 36-87y), most of them were females (65.9%), 17.1% had smoking history and 19.5% biomass exposition as a main risk factor. About diagnosis and clinical features, T790M mutation was detected by liquid biopsy in 29.3% of cases, 36 patients (87.8%) had status performance 0 - 1 (ECOG) and 10 (24.4%) presented brain metastases as progression to the previous line of treatment. About outcomes, the ORR was 70.8%; with a median follow-up of 36 months, the median PFS was 15.2 months (95% IC, 9.6 - 20.7) and median OS since the start osimertinib was 16.3 months (95% IC, 7.6 - 24.9), no differences were found regarding the presence of brain metastases (p = 0.06 and p = 0.32) or type of mutation (p = 0.27 and p = 0.46) in both PFS and OS. Median OS from the start of first-line treatment was 46.6 months (95% IC, 34.5 - 58.7). As supplementary analysis, in the same period of time, 11 T790M-positive patients who did not receive osimertinib as second line of treatment achieved a median OS from the start of first-line treatment of 23.5 months (95% IC, 16.5 - 30.5). This OS was significantly lower compared to those who did receive osimertinib (p = 0.001). Conclusions: This study confirms the efficacy of osimertinib in the real world when used as a second line of treatment in T790M-positive patients, in addition the feasibility of osimertinib in this setting may significantly impact the survival.