Integrating the anti-VEGF-A humanized monoclonal antibody bevacizumab with chemotherapy in advanced colorectal cancer

Recent advances in the treatment of colorectal cancer (CRC) include the incorporation of new drugs to treat a disease where only one drug was known to be active. Oxaliplatin and irinotecan have been incorporated into 5-fluorouracil (5-FU)-based regimens where they have increased response rates and survival. Targeted therapies against the epidermal growth factor pathway and the vascular endothelial growth factor (VEGF) pathway are also on the forefront of oncology research, and are beginning to play a role in the treatment of CRC. Current research efforts are trying to optimize the integration of targeted therapies into chemotherapy regimens such as IFL (irinotecan/bolus 5-FU/leucovorin LV]), FOLFIRI (irinotecan/infusional 5-FU/LV), and FOLFOX (oxaliplatin/infusional 5-FU/LV). In this article, the incorporation of the monoclonal antibody bevacizumab into the IFL regimen will be reviewed in detail. Bevacizumab targets VEGF-A, an important angiogenesis signaling factor commonly expressed in metastatic CRC. The addition of bevacizumab to the IFL regimen significantly increased response rates, median time to progression, and overall survival in patients receiving first-line treatment for CRC, thus leading the Food and Drug Administration to approve bevacizumab for the treatment of CRC in combination with 5-FU-based regimens. Bevacizumab treatment is associated with an increased rate of hypertension. In addition, there may be slight (1%-2%) but relevant increased risks related to gastrointestinal perforations and cardiovascular events. A modest increased risk of wound healing complications was observed in patients who underwent surgery while still receiving, or shortly after receiving, bevacizumab. Bevacizumab plus 5-FU is also a highly active first-line regimen. The role of bevacizumab with other first-line combination regimens, as well as its activity in the second-line setting, is now being determined by ongoing clinical trials.