Hormonal Therapy Plus Bevacizumab in Postmenopausal Patients Who Have Hormone Receptor-Positive Metastatic Breast Cancer: A Phase II Trial of the Sarah Cannon Oncology Research Consortium

Purpose: Preclinical models suggest that addition of anti-vascular endothelial growth factor therapy may improve the efficacy of anti-estrogens in hormone-sensitive breast cancer. This phase II trial evaluated the feasibility and efficacy of bevacizumab added to either anastrozole or fulvestrant in the first-line treatment of patients who have hormone receptor-positive metastatic breast cancer. Methods: Women who had newly diagnosed metastatic hormone receptor-positive breast cancer were eligible. Patients who had relapsed while receiving, or <= 12 months after receiving, adjuvant aromatase inhibitor therapy were treated with bevacizumab (10 mg/kg intravenously every 2 weeks) and fulvestrant (loading dose 500 mg intramuscularly [IM], then 250 mg IM 2 weeks later, then 250 mg IM every 4 weeks). All other patients received fulvestrant/bevacizumab or anastrozole (1 mg orally daily)/bevacizumab. Patients who were HER2-positive could also receive trastuzumab (8 mg/kg loading dose, then 6mg/kg every 3 weeks). Patients were reevaluated after 8 weeks of therapy; responding or stable patients continued treatment until disease progression or unacceptable toxicity. Results: Seventy-nine patients were enrolled (38 were administered anastrozole 41 fulvestrant). Median treatment duration was 8 months in the anastrozole group and 5.5 months in the fulvestrant group. Both regimens were efficacious: overall response rate and median progression-free survival for the entire group were 28% and 13.5 months, respectively. Both regimens were well-tolerated; toxicity was consistent with the known toxicity profiles of each single agent. Conclusion: Bevacizumab combined with either anastrozole or fulvestrant was feasible and active in the first-line treatment of patients who have hormone receptor-positive metastatic breast cancer. Phase III trials evaluating the efficacy of bevacizumab added to endocrine therapy are in progress.