Treatment adherence and clinical outcomes of osimertinib (Osi) among ethnic-minority patients (pts) with EGFR-mutated NSCLC

e18536 Background: Osimertinib (Osi) is widely used in the management of patients with EGFR-mutated NSCLC but there is limited data on the treatment adherence and clinical outcome of Osi in ethnic minorities. This study aims to evaluate race/ethnicity, adherence and other demographic, socioeconomic and clinical factors of patients with NSCLC treated with Osi. Methods: A retrospective cohort study of a total of 102 patients with EGFR mutated NSCLC that were prescribed Osi from 1/1/16-12/31/22 with 46 patients within Montefiore’s own specialty pharmacy system with updated claims data. Adherence was measured using two methods with medication possession ratio (MPR) and proportion of days covered (PDC). Primary endpoint was overall survival (OS) along with secondary endpoints of progression-free survival (PFS) and treatment duration from the start of Osi, compared minority vs non-minority using log-rank testing and survival analysis with cox proportional models. Results: A median follow-up time of 10.5 months (mons), median age of 69 years old and 34.8% self-reported as Non-Hispanic Black (NHB), 45.6% as Hispanic (H), 10.9% as non-Hispanic White (NHW) and 8.7% non-Hispanic Asian. Treatment adherence did not differ between Blacks vs non-Blacks or Hispanics vs non-Hispanics using both MPR or PDC. The median out of pocket cost for our pts after financial assistance and insurance was around $80 (USD). Compared to non-Hispanics, Hispanics had similar OS, PFS and treatment duration. However, compared with Non-Blacks, Blacks had inferior PFS (p=0.021) and borderline significance of worse OS (p=0.052) and shorter duration of Osi (p=0.068). Further results are summarized in the table. Conclusions: Our study demonstrates that treatment adherence did not differ among minority vs. non-minority patients. However, unlike Hispanics who had similar survival to non-Hispanics, Blacks had inferior PFS, OS and shorter duration of Osi compared to Non-Blacks. This warrants further research on the underlying mechanisms to help improve patient care and outcome while undergoing Osi treatment especially in Black pts. [Table: see text]