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Week: 549.5 Guest: Dr. Henry Brem, Dir., Neurology and surgical oncology, Johns Hopkins Hospital, Baltimore, MD Topic: Chemical polymer wafers for cancer post operative sites Producer/Host: Steve Girard
NEMA: Researchers at Johns Hopkins have helped forge a new treatment method for those who have brain tumors....depositing a wafer of chemicals directly into the site of the removed tumor...Dr. Henry Brem, director of neurology and surgical oncology, tells us more...
BREM: Well, we were faced with a problem with brain tumor patients...that there were effective treatments that we saw in the laboratory that worked against brain tumors, yet when they were tried clinically, we didn't see a benefit. The drugs didn't seem to be getting in to the site of the tumor. And the brain has its own natural protective mechanism, called the blood brain barrier, that keeps drugs out from it, to protect it. So we looked - was there a way to get high, sustained levels directly in the brain tumor and bypass the blood brain barrier? So I began working with a colleague at MIT, Robert Langer, who had a biodegradable plastic that could release drugs over a long period of time, and was safe to use.
NEMA: What drug does the wafer carry...?
BREM: Well, our clinical experience has pretty much been with a single drug, called BCNU, which is a chemotherapeutic drug. We have, in the laboratory, used a wide range of both other chemotherapeutic drugs and biological drugs, drugs that control blood vessel proliferation, and therefore starve a tumor. We've even looked at cytokines, which are a way of creating a tumor vaccine, which can be released by polymers. So we're hoping to introduce a wide variety of different drugs directly into tumor sites. And that would be the same whether they're in the brain or in other locations. The potential to give very high concentrations of a drug with very little exposure to the rest of the body, has a lot of potential for cancer therapy.
NEMA: The FDA has recently approved the use of the wafers to deliver on site chemical treatment...but only on recurrent cancers....why not after the initial surgery?
BREM: We've conducted five clinical trials while at the Institution of Clinical Trials, related to using gliudel, which is the BCNU polymer for treating brain tumors. Those trials were the basis of the FDA's decision to approve the gliudel for treating recurring malignant gliomas. There was two studies: one in the United States for safety and one for effectiveness in Europe that addressed using the gliudel for the initial therapy, and those studies were relatively small and the FDA requested further information before making a final decision.
NEMA: In the future, how will this new treatment help patients with brain tumors?
BREM: We certainly see that gliudel will play a part in treating brain tumors. To supplement surgery, radiation therapy and perhaps other medical therapies. Our hope is to use more effective drugs that we currently have developed in the laboratory, for example, taxol is a drug that has been shown very effective for other cancers...but doesn't get into the brain when used in the standard manner. So, we're planning to add taxol into these gliudel polymers, in order to make available to patients a drug that otherwise wouldn't be available to them. So there are many other drugs, as well as biological approaches, such as inhibiting blood vessel proliferation, or even developing tumor vaccines, that can be used in local, high administration that can be achieved with these polymers. This same approach can be used for cancers outside the brain as well, when it's appropriate to do so.
NEMA: Dr. Henry Brem, Director of Neurology and Surgical Oncology at Johns Hopkins...he says though the polymer wafer is not a cure for cancer, it can prolong a patient's life with good quality of life. I'm Steve Girard.
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