Clinical analysis of EGFR‐positive non‐small cell lung cancer patients treated with first‐line afatinib: A Nagano Lung Cancer Research Group

BACKGROUND: In the LUX‐Lung 3 and LUX‐Lung 6 trials, afatinib improved overall survival in previously untreated patients with EGFR 19del mutated non‐small cell lung cancer (NSCLC) compared to chemotherapy. The appropriate management of adverse events and dose reduction of afatinib are important for EGFR‐positive NSCLC patients. We conducted a retrospective and observational study of patients treated with first‐line afatinib for EGFR‐positive NSCLC in Nagano prefecture, Japan, focusing on efficacy and toxicities. METHODS: We retrospectively collected the medical records of NSCLC patients initially treated with afatinib between May 2014 and March 2018. RESULTS: A total of 62 patients with a median age of 67 years and a median body surface area (BSA) of 1.57 m(2) were included. The overall response rate was 87.7% and median progression‐free survival (PFS) was 15.7 months. The median PFS was similar between standard initial dose (40 mg) and reduced initial doses (30 and 20 mg) (15.7 vs. 14.2 months; P = 0.978). The frequency of dose reduction and the discontinuation rate in the 40 mg daily dose group was higher in patients with BSA < 1.58 m(2) (100%) compared to BSA ≥ 1.58 m(2) (68.2%) (P = 0.014). The frequency of diarrhea was higher in patients with BSA < 1.58 m(2) (93.5%) compared to BSA ≥ 1.58 m(2) (71.0%) (P = 0.02). CONCLUSION: In real‐world clinical practice, first‐line afatinib was well managed and was equally as effective as in previous clinical trials of EGFR‐positive NSCLC. BSA is considered a predictive marker for appropriate afatinib dose reduction.