Bevacizumab, a humanized anti-angiogenic monoclonal antibody for the treatment of colorectal cancer

Angiogenesis is the process by which new blood vessels are created from pre-existing vessels. It is essential for the growth and development of normal cells and tissues during embryonic and neonatal development and of tumour cells. Solid tumours rely on having an extensive network of blood vessels for growth and survival. The key mediator of angiogenesis, vascular endothelial growth factor-A (VEGF-A), is critical for the growth of tumours and their subsequent metastasis and is known to initiate angiogenesis. Bevacizumab is a humanized immunoglobulin G monoclonal antibody that binds to VEGF with high specificity, thereby blocking VEGF-mediated signalling pathways and thus angiogenesis. Clinical trials have shown that bevacizumab is effective in prolonging survival in patients with metastatic colorectal cancer (CRC) when combined with standard chemotherapy. Consequently, bevacizumab has been approved in combination with 5-fluorouracil-based chemotherapy for first-line treatment of patients with metastatic CRC. Bevacizumab is generally well tolerated in most patients and does not exacerbate the adverse events associated with conventional chemotherapy. Bevacizumab-related side effects are generally manageable; however, monitoring for hypertension, gastrointestinal perforation, bleeding, proteinuria and thromboembolism is advised, especially in patients with predisposing factors. In addition to demonstrated survival benefits, the convenient dosing schedule and lack of interactions should ensure the successful integration of this novel agent into clinical practice.