A pilot study of metronomic temozolomide treatment in patients with recurrent temozolomide-refractory glioblastoma.

Frequent regular administration of chemotherapeutic agents at low doses, known as 'metronomic chemotherapy', can increase the anti-angiogenic activity of the drugs, as has been confirmed by several other experimental tumor models. The aim of this pilot study was to evaluate the efficacy and safety of metronomic temozolomide (TMZ) treatment in twelve consecutive patients with recurrent TMZ-refractory glioblastoma. The patients were administered by metronomic treatment schedule (continuous low-dose chemotherapy) with TMZ at a daily dose of 40 mg/m(2). The median overall survival (OS) and progression-free survival (PFS) from the start of metronomic treatment were 11.0 months (95% CI, 5.2-10.5 months) and 6.0 months (95% CI, 0-12.3 months), respectively. During the follow-up period, complete response (CR) was not achieved in any patient, partial response (PR) in 2, and stable disease (SD) in 5 patients. Estimated PFS (CR+PR+SD) was 58.3% at 3 months. Grade III/IV toxicity according to the National Cancer Institute Common Toxicity Criteria (NCI CTC) was not found. These results suggest that the change of chemotherapeutic schedule from conventional to metronomic treatment overcomes the chemo-resistance in patients with recurrent TMZ-refractory glio-blastoma without any major toxicity.