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Glioblastoma Multiforme: GliadelŪ Wafers Offer Hope
By Janet W. Bay, M.D.
Malignant glioma, the most common form of brain tumor, is one of the most rapidly progressive malignancies with one of the highest fatality rates. The American Cancer Society reports that approximately 17,500 people develop new cases of primary malignant brain tumors each year.
For over 20 years, no significant successful new treatments for glioblastoma were developed. The blood-brain barrier and the risk of severe complications presented obstacles to the success of systemic drug delivery.
Standard practice consisted of surgery to remove the tumor, followed by radiation therapy. Systemic chemotherapy with carmustine (BCNU) also was often used. Unfortunately, glioblastoma has a very high recurrence rate and generally results in death within a short period.
First New Approach to Malignant Glioblastoma Treatment in 20 Years
GliadelŪ polymer implants are the first fundamentally new approach to malignant glioma treatment in two decades. The small, white, biodegradable wafers are left in surgical cavities created when a brain tumor is removed.
As the dime-sized wafer slowly erodes in the brain, it releases BCNU directly to the tumor site in high concentration over an extended period of time.
Up to eight wafers can be placed directly at the site of the tumor, resulting in a much higher local concentration of BCNU than can be achieved with systemic administration.
Studies Show Longer Median Survival Periods
About 62 mg of BCNU delivered as GliadelŪ achieved substantially higher local brain tissue concentrations with fewer side effects than a 3,000-mg intravenous dose. GliadelŪ provides brain concentrations of BCNU that are 100 to 1,000 times higher than are possible with systemic administration. In current formulation, the duration of GliadelŪ drug delivery is two to three weeks.
Clinical studies worldwide have shown promising results. The first Phase II study with 222 malignant glioma patients at 27 centers undergoing re-operation for recurrent disease increased the median survival time from 23 weeks with placebo to 31 weeks with GliadelŪ.
The second placebo-controlled Phase III study conducted with 32 patients with an initial diagnosis of malignant glioma found one-year survival at 63 percent for GliadelŪ and only 19 percent for placebo. The Lancet did report in its April 22, 1995, issue that patients with diagnoses other than glioblastoma multiforme failed to show a significant survival benefit with GliadelŪ wafers.
Using biodegradable polymers to deliver high doses of prolonged chemotherapy directly to a tumor site is a new tool in the war against cancer. It also may prove important for other cancers as well.
Further studies are under way on other physical formulations of polymers for implantation.
New studies utilizing GliadelŪ in the treatment of metastatic brain tumors are planned.
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