Update on Anti-Angiogenesis Therapy in Colorectal Cancer.

Angiogenesis is a complex biologic process critical to growth and proliferation of colorectal cancer. The safety and efficacy of various anti-angiogenic agents have been investigated in many treatment settings. Bevacizumab, an anti-vascular endothelial growth factor agent, has efficacy in both the first-line setting and beyond progression in metastatic colorectal cancer. The decoy vascular endothelial growth factor receptor aflibercept has been approved in combination with 5-fluorouracil, leucovorin and irinotecan-based chemotherapy in metastatic colorectal cancer patients whose disease has progressed on a prior oxaliplatin-based chemotherapy regimen. The multikinase inhibitor regorafenib is modestly effective in the refractory colorectal cancer setting but confers significant toxicity. Ramucirumab, an anti-vascular endothelial growth factor receptor 2 molecule, has efficacy in combination with 5-fluorouracil, leucovorin and irinotecan after disease progression on a first-line bevacizumab-, oxaliplatin- and fluoropyrimidine-containing regimen. Questions regarding optimal treatment setting, predictive biomarkers of response, and cost effectiveness of these anti-angiogenic agents and others are as yet unanswered.