P3-061Comparative study on safety after primary and secondary treatment in EGFR positive NSCLC administered Osimertinib

Abstract Background Since osimertinib significantly prolonged progression free survival compared with conventional EGFR-TKI and was well-tolerated, it was approved in August 2018 as the primary treatment in EGFR mutation positive non-small cell lung cancer. In this study, we compared the safety of osimertinib administration after the primary and secondary treatments. Method 73 patients with non-small cell lung cancer who received osimertinib from March 2016 to February 2019 were investigated after the follow-up and the adverse events were compared between the first-line treatment (1stOsi) group and the previously treated T790M positive (≥2ndOsi) group. Adverse events were assessed with CTCAE v4.0. Result The median age of the 1stOsi group (n = 23) was 74 years, male: 6 (26%) / female: 17 (74%), the median age of ≥ 2ndOsi group (n = 50) was 70 years, male: 15 (30%) / female 35 (70%). When comparing 1stOsi group with ≥2ndOsi group, significant difference was found between stomatitis [8 (35%) vs 7 (14%), P = 0.04], fatigue [0 (0%) vs 8 (16%), P = 0.04], thrombocytopenia [6 (26%) vs 26 (52%), P = 0.04], anemia [7 (30%) vs 29 (58%), P = 0.03]. Significant difference was observed in adverse events of Grade 3≤ tended to be more frequent in ≥ 2ndOsi group than in 1stOsi group (30% vs 52%, P = 0.08). Discussion From the results, it was found that the administration of osimertinib as the primary treatment showed more frequent rash and stomatitis oral, and the frequency of bone marrow suppression was less frequent as compared with the secondary treatment. In addition, no new adverse event profile is developed and the extent is also mild, so we can deal with the conventional patient education.