Temozolomide As Initial Treatment for Adults With Low-Grade Oligodendrogliomas or Oligoastrocytomas and Correlation With Chromosome 1p Deletions

PURPOSE: To determine the response rate of low-grade oligodendroglial tumors (LGOT) to temozolomide (TMZ) as initial treatment and to evaluate the predictive value of chromosome 1p deletion on the radiologic response. PATIENTS AND METHODS: Adult patients with pathologically proven LGOT with progressive disease on magnetic resonance imaging (MRI) were eligible for the study. TMZ was administered at the starting dose of 200 mg/m2/d for 5 days, repeated every 28 days. Response was evaluated clinically and by central review of MRIs. Chromosome 1p and 19q deletions were detected by the loss of heterozygosity technique. RESULTS: Sixty consecutive patients were included in the study. At the time of analysis, the median number of TMZ cycles delivered was 11. Clinically, 51% of patients improved, particularly those with uncontrolled epilepsy. The objective radiologic response rate was 31% (17% partial response and 14% minor response), whereas 61% of patients had stable disease and 8% experienced disease progression. The median time to maximum tumor response was 12 months (range, 5 to 20 months). Myelosuppression was the most frequent side effect, with grade 3 to 4 toxicity in 8% of patients. Loss of chromosome 1p was associated with objective tumor response (P < .004). CONCLUSION: TMZ is well tolerated and provides a substantial rate of response in LGOT. Chromosome 1p loss is correlated with radiographic response and could be a helpful marker for guiding therapeutic decision making in LGOT.