Chemotherapy for the treatment of oligodendroglial tumors

Abstract

Oligodendroglial tumors include the highly chemosensitive oligodendroglioma and mixed oligoastrocytoma. Patients with these tumors have a longer median survival and time to disease progression than patients with other brain tumor types, but the range is wide and the disease is inevitably fatal. Because of their chemosensitivity and the potential for radiation toxicity, lowgrade oligodendroglioma are increasingly being treated with adjuvant or neoadjuvant chemotherapy before radiation therapy. Approximately two thirds of patients with the more aggressive form (anaplastic oligodendroglioma) have shown substantial response to first-line procarbazine/lomustine/vincristine (PCV) therapy. However, experience with chemotherapy for relapse of disease following PCV therapy is limited. Several small trials have shown the safety and activity of temozolomide (Temodar in the United States, Temodal globally; Schering Corporation, Kenilworth, NJ) in oligodendroglioma, regardless of prior PCV therapy. An open-label, phase II trial of temozolomide in 47 patients with relapsed oligodendroglioma showed an objective response rate of 43%, of which seven (15%) were complete responses. Median progression-free survival was 6 months and 34% of patients were disease-free at 12 months. Median survival was 26 months for complete responders and 11 months for partial responders. Temozolomide was well tolerated. The only grade 3/4 toxicity with temozolomide treatment was thrombocytopenia, which occurred in ≤ 5% of the 382 treatment cycles administered. The encouraging results of ongoing trials with temozolomide suggest the potential for its use as a first-line therapy in this patient population.