453P Development of skin rash within the first week is a potential surrogate marker of effect in afatinib for EGFR mutant NSCLC: Okayama Lung Cancer Study Group Experience

Aim/Background: Epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), gefitinib or erlotinib, is a key drug in patiens with EGFR-mt NSCLC. Its efficacy would be predicted by development of skin rash. However, although afatinib, 2nd generation EGFR-TKI, has proved to be effective, it has not been fully evaluated if the occurrence of any toxicity is a potential surrogate for its efficacy. Now, we investigated a potential association between development of toxicity and efficacy of afatinib. Methods: We retrospectively studied consecutive 49 patients with EGFR-mutant NSCLC who received afatinib therapy between 2009 and 2015. Relationship with several toxicities and tumor response was examined. To avoid the potential bias of early treatment failure, we excluded pts who failed to continue afatinib for more than 1week. Results: The Grade 2 or worse common adverse events (AEs) included skin rash in 17 patients (35%), diarrhea in 19 (39%) and mucositis in 15 (31%). Of these, number of patients who developed ≥ Grade 2 AEs within the first week was 5 (10%; skin rash), 12 (25%; diarrhea) and 4 (8%; mucositis). As for objective response, 21 (43%) of the 49 had partial response. In association with AEs and antitumor effect, those who had Grade 2 or worse skin rash within the first week tended to have better tumor response as compared with those who did not have (80% vs. 39%; p = 0.077), (Table).Tabled 1Relationship with early development of adverse events and responseNo. of patientsResponse (-)No. of patients (%)Response (+)≥ G2 hepatitis yes no1 270 (0%) 21(44%)0.382≥ G2 skin rash yes no1 274 (80%) 17 (39%)0.077≥ G2 diarrhea yes no6 226 (50%) 15 (41%)0.565≥ G2 paronychia yes no1 270 (0%) 21 (44%)0.382≥ G2 mucositis yes no2 262 (50%) 19 (42%)0.763≥ G2 gastritis yes no0 280 (0%) 21 (43%)≥ G2 dysgeusia yes no0 280 (%) 21 (43%)≥ G2 ILD yes no0 280 (0%) 21 (43%) Open table in a new tab Conclusions: We demonstrated that early development of skin rash would predict the response to afatinib monotherapy. Disclosure: K. Hotta: received honoraria from Eli Lilly Japan, Taiho Pharmaceutical, Chugai Pharmaceutical and Sanofi-Aventis. N. Nogami: received honoraria from AstraZeneca, Chugai Pharmaceutical, Taiho Pharmaceutical and Boehringer Ingelheim. N. Takigawa: received honoraria from Chugai Pharmaceutical, Taiho Pharmaceutical and Sanofi-Aventis. M. Tanimoto: received donated funds from Nihon Kayaku. K. Kiura: received honoraria from Eli Lilly Japan, Nihon Kayaku, AstraZeneca, Daiichi-Sankyo Pharmaceutical, Chugai Pharmaceutical, Taiho Pharmaceutical and Sanofi-Aventis; received research donated funds from Nihon Kayaku. All other authors have declared no conflicts of interest.