Background

Before mutation testing of the epidermal growth factor receptor (EGFR) gene was recognized as highly associated with the activity of EGFR tyrosine kinase inhibitors (TKIs), clinically defined patient populations with bronchioloalveolar carcinoma (BAC) and never smokers were identified as likely to benefit from EGFR TKIs. From preclinical and clinical data suggesting potentially improved efficacy with a combination of an EGFR TKI and the antiangiogenic agent bevacizumab, the Southwestern Oncology Group (SWOG) initiated paired phase II trials to evaluate the combination of erlotinib/bevacizumab in patients with advanced BAC (SWOG S0635) or never smokers with advanced lung adenocarcinoma (SWOG S0636).

Materials and methods

Eligible patients with BAC or adenocarcinoma with BAC features (SWOG S0635) or never smokers with advanced lung adenocarcinoma (SWOG S0636) received erlotinib 150 mg/day with bevacizumab 15 mg/kg until progression or prohibitive toxicity. Never smokers with BAC were preferentially enrolled to SWOG S0636. The primary endpoint for both trials was overall survival.

Results

A total of 84 patients were enrolled in the SWOG S0635 trial and 85 in the SWOG S0636 trial. The objective response rate was 22% (3% complete response) in the SWOG S0635 trial and 50% (38% confirmed; 3% complete response) in the SWOG S0636 trial. The median progression-free survival was 5 and 7.4 months in the S0635 and S0636 trials, respectively. The median overall survival was 21 and 29.8 months, respectively. Toxicity consisted mainly of rash and diarrhea in both trials.

Conclusion

Although the field has moved toward molecular, rather than clinical, selection of patients as optimal candidates for EGFR TKI therapy, these results support the hypothesis that a subset of patients in whom erlotinib is particularly active could receive an incremental benefit from the addition of bevacizumab.