Bevacizumab (trade name Avastin) is a monoclonal antibody against vascular endothelial growth factor. It is used in the treatment of cancer, where it inhibits tumor growth by blocking the formation of new blood vessels. Bevacizumab was the first clinically available angiogenesis inhibitor in the United States.

Bevacizumab was approved by the U.S. Food and Drug Administration in 2004 for use in combination with standard chemotherapy in the treatment of metastatic colon cancer and most forms of metastatic non-small cell lung cancer[2]. Currently, several additional late-stage clinical studies are underway to determine its safety and effectiveness for patients with: adjuvant / non-metastatic colon cancer, metastatic breast cancer, metastatic renal cell carcinoma, metastatic glioblastoma multiforme, metastatic ovarian cancer, metastatic hormone-refractory prostate cancer, and metastatic metastatic or unresectable locally advanced pancreatic cancer.

Bevacizumab was developed by Genentech and is marketed in the United States by Genentech and elsewhere by Roche (Genentech's parent company), under the brand name Avastin.