O1–146 - Rechallenge with EGFR-TKI after a Drug Holiday, Retrospective Study in Single Institution

Abstract

Purpose: Patients with advanced non-squamous non-small cell lung cancer (Non-Sq NSCLC) harboring somatic EGFR mutations respond well to the EGFR tyrosine kinase inhibitor (TKI) in initial therapy. However, patients with an activating EGFR mutation who initially respond to EGFR-TKI eventually relapse with resistant disease. The molecular mechanism of resistance is poorly understood. The aim of this retrospective study was to investigate whether rechallenge with EGFR-TKI after a drug holiday was beneficial. Methods: We retrospectively reviewed the medical records of 22 patients with stage IV Non-Sq NSCLC who experienced progressive disease after 1st EGFR-TKI, were subsequently treated with cytotoxic drug and retreated with EGFR-TKI at renewed progression. Results: Twenty two patients (10 male, 12 female, median age 66 years(50-84 years), all adenocarcinoma, EGFR mutation status; Ex19 del./L858R/other/unknown=10/9/1/2) received treatment with 2nd EGFR-TKI. 1st response rate(RR), 1st disease control rate (DCR), 1st time to treatment failure(TTF) and 1st progression free survival(PFS) were 59%, 100%, 8.5M and 9.5M, respectively. 2nd RR, 2nd DCR, 2nd TTF and 2nd PFS were 0%, 72%, 7M and 7M, respectively. Median drug holidays of EGFR-TKI was 7.5M. Conclusions: Our findings suggest that rechallenge with 2nd EGFR-TKI is an option for patients with Non-Sq NSCLC who received a benefit from 1st EGFR-TKI and experienced progressive disease after cytotoxic chemotherapy.