Retreatment With EGFR-Tyrosine Kinase Inhibitor After Disease Progression Following Gefitinib Induction and Chemoradiotherapy in EGFR-Mutant Stage III Non-small Lung Cancer: An Efficacy and Safety Analysis of the LOGIK0902/OLCSG0905 Study.

Background and objective We had previously conducted a phase II study (LOGIK0902/OLCSG0905 study) involving the eight-week administration of gefitinib, followed by cisplatin-based chemoradiotherapy, to treat locally advanced, epidermal growth factor receptor (EGFR)-mutated, non-small cell lung cancer (NSCLC). Despite favorable overall survival outcomes, more than half of the patients relapsed after the protocol therapy, highlighting the need to clarify the clinical significance of retreatment with EGFR-tyrosine kinase inhibitors (TKIs). We investigated the efficacy and safety of EGFR-TKI retreatment after disease progression. Materials and methods We included 14 patients who relapsed after the protocol treatment and received any type of EGFR-TKI as post-progression treatment in this sub-analysis. We evaluated the efficacy and safety of retreatment with EGFR-TKI in these patients. Results Among the 14 patients, 11 (78.6%) responded to the induction of gefitinib in the treatment protocol. After relapse, 9/14 patients (64.3%) received gefitinib, 3/14 (21.4%) received afatinib, and 2/14 (14.3%) received erlotinib monotherapy, respectively. The median duration of post-progression EGFR-TKI treatment was 17.9 (0.7-45.5) months. The overall response rate (ORR) and disease control rate were 64.3% [9/14 patients; 95% confidence interval (CI): 35.1%-87.2%] and 85.7% (12/14 patients; 95% CI: 57.2%-98.2%), respectively. The median progression-free survival (PFS) and median survival durations after the initiation of EGFR-TKI retreatment were 11.8 months (95% CI: 5.7-20.7 months) and 47.4 months (95% CI: 31.8 months to not estimable), respectively. Adverse events were comparable to those previously reported. Conclusions Patients with disease progression after protocol therapy demonstrated sensitivity to retreatment with an EGFR-TKI, with acceptable safety.