Why doesn’t Avastin turn off beneficial processes that are important to good health when it blocks VEGF?
F: VEGF is extremely important in certain periods of development—in embryonic development or early postnatal development. In an adult, it turns out to be mostly important in cyclical angiogenesis, like the female reproductive cycle, and to some degree for wound healing. But other than that, mature blood vessels seem to be relatively independent of VEGF. How do you pick which group of patients you’ll test the drug in first? F: In this case, the drug worked against virtually every kind of tumor in the animal models. And the early clinical data showed very broad efficacy. I still suspect that if you treat early in the process, the majority of tumors will respond to some degree. We chose colorectal cancer because, unfortunately, there are a relatively large number of people for whom bleeding is the first symptom that they have advanced, metastatic colon cancer. It was a big group of untreated people. How is Avastin administered? F: It’s given intravenously—systemically—typically every two
