What is the mechanism of action of Avastin?
Hurwitz: For tumors to grow, they need a blood supply, and for blood vessels to grow, they need growth factors. VEGF appears to be one of the most important of these growth factors. [Avastin] appears to work by binding to the VEGF receptor and blocking signals for blood vessel growth. Without these signals, tumor blood vessels are stunted in their growth, causing a similar effect in the tumor itself. VEGF is the first growth factor shown to be effective in this fashion. Medscape: How effective is Avastin in treating metastatic colorectal cancer? Hurwitz: For patients with newly diagnosed metastatic colorectal cancer, [Avastin] represents a fairly big advance. This drug is able to prolong survival by about five months from a baseline median survival of 15.6 months for [patients who just received standard treatment] to 20.3 months for [those getting standard treatment plus Avastin]. This correlates with increasing survival by about one third. If a patient has 15 months’ average life expe
