Osimertinib in patients with T790M-positive advanced non-small cell lung cancer: Korean subgroup analysis from phase II studies

Purpose Osimertinib is a third-generation, irreversible, oral epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) that potently and selectively inhibits both EGFR sensitizing mutation and EGFR T790M and has demonstrated efficacy in non-small cell lung cancer (NSCLC) central nervous system (CNS) metastases. We present results of a subgroup analysis of Korean patients from the pooled data of two global phase II trials: AURA extension (NCT01802632) and AURA2 (NCT02094261). Materials and Methods Enrolled patients had EGFR T790M-positive NSCLC and disease progression during or after EGFR-TKI therapy. Patients received osimertinib 80 mg orally once daily until disease progression. The primary endpoint was objective response rate (ORR). Results In total, 66 Korean patients received osimertinib treatment with a median treatment duration of 19 months. In the evaluable-for-response population (n=62), ORR was 74% (95% confidence interval [CI], 61.5 to 84.5) and median duration of response was 9.8 months (95% CI, 7.1 to 16.8). In the full analysis set (n=66), median progression-free survival was 10.9 months (95% CI, 8.3 to 15.0; data cutoff November 1, 2016), and median overall survival was 29.2 months (95% CI, 24.8 to 35.7; data cutoff May 1, 2018). Eight patients with CNS metastases were evaluable for response, none of whom showed CNS progression. The most common adverse events were rash (53%), cough (33%), paronychia, diarrhea, and decreased appetite (each 32%). Conclusion Efficacy and safety profiles of osimertinib in this subgroup are consistent with the global phase II pooled population, which supports osimertinib as a recommended treatment for Korean patients with T790M positive NSCLC.