The basic idea behind antiangiogenesis is simple: To stop a tumor, you must starve it to death. Yet, like many simple ideas, this one has been difficult to achieve — until now. Antiangiogenic drugs work by halting the development of the blood vessels that cancerous cells need to grow. Unlike chemotherapy, however, antiangiogenesis focuses on the tumor, so it doesn’t attack healthy cells.

The commercial and humanitarian implications are huge. Consider just one extremely promising application: colorectal cancer. In 2000, the World Health Organization reported that almost 950,000 people worldwide were diagnosed with colorectal cancer and half of the patients died. In the U.S. alone, colorectal cancer is diagnosed in more than 130,000 people every year. It is the third most common cancer in men and women, representing 10 to 15 percent of all cancers, and it is almost always fatal once it reaches the advanced stages.

Now, Genentech is developing a colon cancer drug called Avastin1 specifically to restrict the blood supply to tumors. The latest results, which show that Avastin can significantly improve survival in advanced colorectal cancer compared to chemotherapy alone, are very exciting. This represents the first, long-hoped for clinical evidence that antiangiogenic therapy has a significant role to play in cancer treatment. In the 900-patient randomized Phase III study, Avastin increased survival duration by over 30 percent when combined with first-line chemotherapy for advanced colorectal cancer.

In addition to the 30 percent survival rate, the study found that when Avastin was added to first-line chemotherapy, patient survival time was extended from 15.6 months with chemotherapy alone to 20.3 months. Importantly, these clinical benefits were seen across all patient subgroups in the population. The results of this important study clearly demonstrate that blocking the blood supply to tumors has real potential to help the majority of patients to a degree that is highly clinically relevant. For some patients, the results are truly remarkable.

If the Food and Drug Administration decides to approve Avastin for colon cancer by the end of March 2004, as expected, this is likely to be just the first of a whole series of antiangiogenesis drugs that will transform medicine in the coming decade. In this arena, Genentech will be joined by ...