Anti-angiogenesis research began more than 35 years ago with the work of the late Judah Folkman, MD. The ACS supported Dr. Folkman's research early in his career. Dr. Folkman's early focus was on substances made by the body itself to curb blood vessel growth. Although several substances were found, for the most part they have not yet been shown to be useful as drugs.

But many man-made compounds that affect blood vessel growth have been created. Some are being studied in the lab or in clinical trials (see below), and some are already being used in doctors' offices.

Several hundred clinical trials of anti-angiogenesis drugs are now under way. While not all of these drugs will prove to be useful against cancer, many will help give patients more options for treatment.

How new drugs are tested

A new drug is first tested on cancer cells grown in lab dishes (cell culture studies). If the drug kills the cells or slows their growth enough, testing is done to see if the drug works in animals with cancer. A drug that seems to be safe and effective in animals may then be tested in humans in clinical trials, which are usually carried out in 4 phases.

Phase I clinical trials: The purpose of a phase I study is to find out how safe a new treatment is and to find the best dose for future studies. Doctors watch patients carefully for any harmful side effects. They start by giving very low doses of the drug to the first few patients and increase the dose for later groups of patients. This is done until the desired effects are seen or until serious side effects appear. Although doctors are hoping to help patients, the main purpose of a phase I study is to test the safety of the drug.

Phase II clinical trials: These studies are designed to see if the drug works. Patients are given the best dose of the drug as determined from the phase I study and closely watched for an effect on the cancer. The doctors also look for side effects.

Phase III clinical trials: Phase III studies have large numbers of patients -- usually hundreds. One group (the control group) gets the current standard (most accepted) treatment. The other group gets the new treatment. All patients in phase III studies are closely watched. The study is stopped if the side effects of the new treatment are too severe or if one group has a much better result than the others.

Phase IV clinical trials: Once a drug has been approved by the FDA and is available for all patients, it is still studied in other clinical trials (sometimes called phase IV studies). This way more can be learned about short-term and long-term side effects and safety as the drug is used in larger numbers of patients with many types of diseases. Doctors can also learn more about how well the drug works, and if it might be helpful when used in other ways, such as along with other treatments.

Please see our document, Clinical Trials: What You Need to Know if you want more information.

Last Medical Review: 03/10/2009
Last Revised: 03/10/2009

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