VEGFR2 cytoplasmic expression (VEGFR2ce) in relation to survival in metastatic breast cancer (MBC) patients (pts) treated with bevacizumab (Bev).

Abstract

11523 Background: Bev is a monoclonal antibody that binds to VEGFA that demonstrated improved progression free survival (PFS) in MBC clinical trials. VEGFR2, NOTCH1, Integrin a1b2 and ILK are angiogenesis-related proteins possibly related with Bev efficacy. The correlation of these proteins expression and Bev survival variables was evaluated. Methods: We retrospectively analyzed 1st line chemotherapy in two HER2 negative MBC cohorts. Pts were treated between May-07 and July-14. Cohort 1 (C1) was treated with paclitaxel and Cohort 2 (C2) with paclitaxel and Bev. Expression of biomarkers was determined by immunohistochemistry. Tumor samples were arranged on a tissue microarray. Survival curves were calculated by Kaplan-Meier method and log-rank test. Cox model was used in multivariate analysis. Results: C1 had 42 pts. Median age was 63y. Tumor subtypes were divided in luminal (92.9%) and triple negative (TN) (7.1%). Visceral metastasis (mets) were present in 71.4%. Median follow-up (mFUP) time was 32.1m. mPFS was 8.0m and mOS was 33.5m. C2 had 29 pts. Median age was 57y. Luminal 79.3%; TN 20.7%; Visceral mets 79.3%; mFUP 38m. mPFS was 10.5m and mOS was 47m. In C2, high VEGFR2ce was correlated with improved PFS (high VEGFR2 16.5m x low VEGFR2 6.8m, p = 0.025). Breast cancer subtype, metastasis pattern and VEGFR2 expression were included in the multivariate analysis for PFS. VEGFR2 remained as independent factor (HR 0.35; IC95% 0.14 – 0.85, p = 0.021). In C1, VEGFR2 was not correlated with improved PFS (high VEGFR2 8.6m x low VEGFR2 8.0m, p = 0.24). Other markers were not associated with PFS. Conclusions: High VEGFR2ce was associated with increased PFS in patients treated with Bev. In MBC VEGFR2 may have a role as a predictive tool on benefit of antiangiogenic therapy.