Pilot trial of preoperative (neoadjuvant) letrozole in combination with bevacizumab in postmenopausal women with newly diagnosed estrogen receptor- or progesterone receptor-positive breast cancer.

INTRODUCTION: Tumor content or expression of vascular endothelial growth factor (VEGF) is associated with impaired efficacy of antiestrogen adjuvant therapy. We designed a pilot study to assess the feasibility and short-term efficacy of neoadjuvant letrozole and bevacizumab (anti-VEGF) in postmenopausal women with stage II and III estrogen receptor/progesterone receptor-positive breast cancer. PATIENTS AND METHODS: Patients were treated with a neoadjuvant regimen of letrozole orally 2.5 mg/day and bevacizumab intravenously 15 mg/kg every 3 weeks for a total of 24 weeks before the surgical treatment of their breast cancer. Patients were followed for toxicity at 3-week intervals, and tumor assessment (a physical examination and ultrasound) was performed at 6-week intervals. Positron emission tomography (PET) scans were performed before therapy and 6 weeks after the initiation of therapy.
RESULTS: Twenty-five evaluable patients were treated. The regimen was well-tolerated, except in 2 patients who were taken off the study for difficulties controlling their hypertension. An objective clinical response occurred in 17 of 25 patients (68%), including 16% complete responses (CRs) and 52% partial responses. The 4 patients with clinical CRs manifested pathologic CRs in their breasts (16%), although 1 patient had residual tumor cells in her axillary nodes. Eight of 25 patients (32%) attained stage 0 or 1 status. The PET scan response at 6 weeks correlated with clinical CRs and breast pathologic CRs at 24 weeks (P < .0036).
CONCLUSION: Combination neoadjuvant therapy with letrozole and bevacizumab was well-tolerated and resulted in impressive clinical and pathologic responses. The Translational Breast Cancer Research Consortium has an ongoing randomized phase II trial of this regimen in this patient population.

RCT Entities:   Population Interventions Outcomes