Phase I study of afatinib plus bevacizumab in patients with advanced non-squamous non-small cell lung cancer harboring EGFR mutations

Background: Afatinib is a second-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). Combination therapies with first-generation EGFR-TKIs and bevacizumab have been reported to prolong progression-free survival (PFS). However, there are few data on the combination of afatinib and bevacizumab. Methods: In this phase I trial, we evaluated the safety of afatinib plus bevacizumab in patients with advanced non-squamous non-small cell lung cancer (NSCLC) harboring EGFR mutations. This study consisted of two cohorts. In the dose-finding cohort, enrolled patients were treated with afatinib at a dose of 20, 30, or 40 mg/ day (days 1-21) plus bevacizumab at a dose of 15 mg/kg (day 1) in 21- day cycles. This cohort was performed according to a 3 + 3 manner. In the expansion cohort, enrolled patients received the recommended dose (RD) based on the results of the dose-finding cohort. The serum trough concentration of afatinib was determined at the steady state. Results: Seventeen patients were enrolled in this study (6 patients in the dose-finding cohort and 11 patients in the expansion cohort). There were no dose-limiting toxicities (DLTs) with afatinib at a dose of 30 mg/day. With afatinib at a dose of 40 mg/day, two of two patients experienced DLTs (grade 3 diarrhea) in cycle 1. With these results, afatinib at a dose of 30 mg/day plus bevacizumab at a dose of 15 mg/kg was determined as the RD. Eleven patients in the expansion cohort were treated with the RD. Common treatment-related adverse events (AEs) with the RD were diarrhea (79%), rash (71%), perionychia (64%), and stomatitis (50%). Grade 3 AEs with the RD were diarrhea (7%), perionychia (7%), and hypertension (7%). There were no grade 4/5 AEs or cases of interstitial lung disease. Dose-proportional increases in serum afatinib trough concentrations at steady state were not observed. The response rates (RRs) and disease control rates were 55% and 100% in EGFR-TKI-naive patients. Re-biopsy was performed in eight patients after progressive disease following the study treatment, and three patients acquired a T790M mutation. Conclusions: Afatinib at a dose of 30 mg/day plus bevacizumab at a dose of 15 mg/kg q3w is well tolerated.