P1.14-30 Phase I Study of Afatinib Plus Bevacizumab in Patients with Advanced Non-Small Cell Lung Cancer Harboring EGFR Mutations

Abstract

Afatinib, a second-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), is one of the standard therapies for patients with advanced non-small cell lung cancer (NSCLC) harboring EGFR mutations. The first-generation EGFR-TKIs in combination with bevacizumab have been reported to improve progression-free survival (PFS). However, data on afatinib plus bevacizumab are limited. In this phase I study, we examined the safety and the efficacy of afatinib plus bevacizumab in patients with advanced non-squamous NSCLC harboring EGFR mutations. This study comprised two cohorts. In the dose-finding cohort, eligible patients received afatinib 20, 30, or 40 mg/day (days 1–21) plus bevacizumab 15 mg/kg (day 1) in 21-day cycles. This cohort was designed and conducted in a 3 + 3 manner. In the expansion cohort, the patients were treated with the recommended dose (RD) based on the findings in the dose-finding cohort, and we evaluated the preliminary efficacy of this combination therapy. The serum trough concentration of afatinib was assessed at the steady state. Sixteen patients were enrolled in this study (5 patients in the dose-finding cohort and 11 patients in the expansion cohort). No dose-limiting toxicities (DLTs) occurred with afatinib 30 mg/day. With afatinib 40 mg/day, 2 out of 2 patients had DLTs (grade 3 diarrhea) in cycle 1. From these results, afatinib 30 mg/day plus bevacizumab 15 mg/kg was decided as the RD. Additionally, 11 patients in the expansion cohort were treated with RD. Common treatment-emergent 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 and interstitial lung disease. The response rates and median PFS were 56% and 16.8 months in EGFR-TKI naïve patients, and 0% and 4.9 months in patients pretreated with EGFR-TKIs. The median serum concentration at the steady state was 13.7 ng/mL (range: 8.1–38.1 ng/mL) in the patients treated with the RD. Rebiopsy was conducted in eight patients after disease progression with afatinib plus bevacizumab, and three patients acquired an exon 20 T790M mutation. Afatinib 30 mg/day plus bevacizumab 15 mg/kg was well tolerated. Large-scale studies are warranted to evaluate the efficacy of this combination therapy.