Phase I study of continuous afatinib (BIBW 2992) in patients with advanced non-small cell lung cancer after prior chemotherapy/erlotinib/gefitinib (LUX-Lung 4)

Purpose This Phase I study determined the maximum-tolerated dose (MTD) of afatinib (Afatinib is an investigational compound and its safety and efficacy have not yet been established) (BIBW 2992; trade name not yet approved by FDA), an irreversible inhibitor of epidermal growth factor receptor (EGFR)/human epidermal growth factor receptor (HER) 1 and 2, up to a dose of 50 mg/day in advanced non-small cell lung cancer (NSCLC), to establish the recommended dose for Phase II. Methods Patients with advanced NSCLC who had received prior platinum-doublet chemotherapy and/or erlotinib/gefitinib therapy, or who were ineligible for, or not amenable to, treatment with established therapies, received oral afatinib once daily. The MTD was determined based on dose-limiting toxicities (DLTs); other assessments included safety, pharmacokinetic profile, antitumour activity according to response evaluation criteria in solid tumours and EGFR/HER1 mutation analysis where possible. Results Twelve evaluable patients were treated at doses of 20-50 mg/day. One DLT was observed at 50 mg/day in Course 1 (Grade 3 mucositis). The most frequent drug-related adverse events were diarrhoea, dry skin, stomatitis, rash, paronychia and anorexia; most were Grade 1 or 2. Six out of 12 patients had tumour size reductions; durable stable disease was achieved in three patients including one with EGFR/HER1 exon 19 and T790 M mutations. Peak plasma concentrations of afatinib were reached 3-4 h after administration and declined with a half-life of 30-40 h. Afatinib 50 mg/day was well tolerated with an acceptable safety profile during Phase I. Conclusion Recommended dose for Phase II was defined as 50 mg/day for Japanese patients; the same as for non-Japanese patients.