Capillary density has no value as an early biomarker of bevacizumab efficacy in metastatic colorectal cancers: a prospective clinical trial

Background Bevacizumab is a recombinant humanized monoclonal immunoglobulin G1 antibody targeting VEGF-A. It is currently used with chemotherapy as the first- or second-line therapy in metastatic colorectal cancer. Previous studies have showed that anti-angiogenic agents decrease capillary density. We evaluated the link between decreased capillary density and the response to bevacizumab-based chemotherapy. Results Overall, 43 patients with metastatic colorectal cancer treated with first-line bevacizumab-based chemotherapy were enrolled. At Day 90, progressive disease was observed in 12 patients (27.9%). All patients presented decreased capillary density. ROC analysis at different time points and capillary density variation showed a poor diagnostic performance regarding response at Day 90. Materials and Methods From 2013 to 2015, patients with metastatic colorectal cancer treated in our French cancer care center and eligible for bevacizumab with chemotherapy were enrolled in a prospective single-center study. Capillary density was assessed using capillaroscopy at Day 1, Day 15 and Day 30. Response to bevacizumab was assessed at Day90 according to CHUN criteria. Conclusions Capillary density measured using capillaroscopy is not a good predictor of the early response to bevacizumab-based chemotherapy. (NCT01810744).