456P Practical use of osimertinib in Japanese patients with EGFR T790M mutation positive advanced non-small-cell lung cancer

Abstract

Background: Osimertinib (AZD9291) is an irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) with activity against both EGFR-TKI sensitizing and T790M resistant mutation-positive advanced non-small cell lung cancer (NSCLC), and which has been approved by the Ministry of Health, Labour and Welfare in Japan. Methods: To assess the safety and clinical activity for practical use of osimertinib in Japanese patients, we retrospectively reviewed medical records of patients with EGFR T790M mutation positive advanced NSCLC who initiated osimertinib therapy at the Shizuoka Cancer Center between March 28th and July 31th, 2016. Results: This study included 20 patients with a median age of 65 (range, 38-83) years. A total of 65% of the patients (13 of 20) were women, 75% (15 of 20) had an ECOG performance-status score of 0 or 1, and all the patients had adenocarcinoma on histologic analysis. All the patients had received at least one prior EGFR-TKI, and 25% (5 of 20) had received immediate prior nivolumab therapy. All 20 patients were administered 80 mg osimertinib once daily. Of these patients, four (20%) developed interstitial lung disease (ILD); two patients with grade 1, one patient with grade 2, and one patient with grade 3. The median time to the onset of ILD from osimertinib initiation was 6 (range, 4-12) weeks. The incidence of ILD was significantly higher in patients with immediate prior nivolumab therapy than in those without it (60% vs. 7%, P=0.02). Among 13 evaluable patients, the overall response rate was 69%, with nine partial responses, three stable diseases, one progressive disease. Conclusions: Osimertinib therapy demonstrated favorable clinical activity in Japanese patients with EGFR T790M mutation positive advanced NSCLC, however sequential administration of osimertinib immediately after nivolumab therapy may increase the risk of developing ILD.