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

Abstract 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.