Implantable slow-release chemotherapeutic polymers for the treatment of malignant brain tumors

Background: Despite significant advances in neurosurgery, radiation therapy, and chemotherapy, the prognosis for patients with malignant brain tumors remains dismal. In an effort to improve control of local disease, we have developed a biodegradable, controlled-release polymer that is implanted directly at the tumor site. Methods: The preclinical and clinical development of the polymeric delivery of chemotherapeutic agents for treatment of patients with malignant gliomas is reviewed. Results: Carmustine (BCNU)- impregnated biodegradable polymer is the first new therapy approved by the FDA for patients with gliomas in 23 years. This delivery system provides high local concentration of drug with minimal systemic toxicity and obviates the need for drug to cross the blood-brain barrier. Randomized, multi- institutional, double-blinded, placebo-controlled studies have shown improved survival in patients treated for gliomas both at initial presentation and at recurrence. Several clinical principles have emerged from the use of this polymer system, and further applications are currently being investigated. Conclusions: Local delivery of therapeutic agents via biodegradable polymers may play an increasing role in patients with brain tumors.