Abstract
INTRODUCTION: As systemic therapy improves, brain metastases are increasingly common in patients with breast cancer. Unfortunately, effective therapy with durable control has remained elusive [1]. Combining bevacizumab and cyototoxic chemotherapy is an appealing approach as the anti-angiogenic effect of bevicizumab may improve delivery of cytotoxic drugs to brain tumors. METHODS: We conducted a Phase II study of patients with parenchymal brain metastasis treated with bevacizumab and carboplatin [2]. Patients could have any hormone receptor status or any number of prior therapies. Patients with HER2+ breast cancer also received trastuzamab. Correlative perfusion MRI scans to look at tumor perfusion, blood volume, vessel calibers and relative oxygen saturation (ΔSO(2)) levels were performed at baseline, day 1, and after 2 months of therapy [3, 4]. For consistency, the largest contrast-enhancing lesion in each patient visible on all three MR visits was selected for analysis. RESULTS: Thirty-eight patients were enrolled in the study of which 32 had, paired evaluable imaging datasets. Compared to baseline, 12/32 patients were identified as responders by a durable increase in ΔSO(2) levels at day 1 and at 2 months above a 5% measurement error threshold. The remaining patients were identified by stable (15/32) or reduced (5/32) ΔSO(2) levels. Patients responding to therapy showed increased tumor perfusion (Mann-Whitney; P<0.01) and prolonged survival (625 versus 400 days, Cox regression; P<0.05) Fig. 1B). A collective and selective pruning of macroscopic tumor vessels (>10 µm) were seen across all patients. CONCLUSIONS: Similar to primary brain tumors [2, 3], perfusion MRI demonstrates that anti-angiogenic therapy can induce vascular normalization in a subset of patients with metastatic breast cancer to the brain. Our data indicate that the vascular response may also be associated with improved survival. [1] Lin NU, Lancet Oncol 2013 [2] Sorensen AG, Cancer Res 2012 [3] Emblem KE, Nat Med 2013