Background: Continuous research into new strategies and chemotherapy agents for the treatment of malignant high-grade gliomas have led to the synthesis of a new chemotherapy drug, temozolomide (TMZ), with a lower toxicity profile compared to conventional chemotherapy agents, such as nitrosoureas. Temozolomide is an oral alkylating chemotherapy agent licensed for the treatment of recurrent high-grade gliomas, anaplastic astrocytoma (AA) and glioblastoma multiforme (GBM). Because of its favorable pharmacokinetic and pharmacodynamic properties and improved tolerability, TMZ is now under investigation for concomitant use with radiotherapy in patients with newly-diagnosed GBM. We present a phase II clinical trial investigating the efficacy and safety of radio-chemotherapy combined treatment using TMZ, followed by six cycles of adjuvant chemotherapy with TMZ, in patients with newly-diagnosed GBM who have undergone debulking surgery or biopsy only.
Patients and methods: Twenty-one patients with newly histologically-diagnosed GBM were enrolled into this phase II clinical trial. In phase I of the study, TMZ (75 mg/m2/day per 7 days/wk for 6 weeks) was orally administered to patients concomitantly with radiotherapy (RT) (2 Gy per fraction once daily, per 5 days/wk for 6 weeks). In phase II of the study, four weeks after completion of RT, a monochemotherapy using TMZ was administered at the dosage of 200 mg/m2/day per 5 days every 28 days for 6 cycles. Primary end-points were the safety and tolerability profile of this two-phase combined treatment and secondary end-points were the objective response and survival rates at twelve months and eighteen months from study entry.
Results: The one-year survival rate of patients treated with the investigated multimodality treatment was 58% and median survival time was 15.7 months. Concomitant RT plus TMZ (phase I) followed by adjuvant TMZ (phase 2) were well-tolerated; indeed, nonhematological adverse events were rare and mild to moderate in severity; grade 3 and 4 neutropenia and thrombocytopenia were the major-related hematological side-effects observed in only 2 and 3 of all patients in phase I and 4 patients in phase II. We found that the combination of radio- and chemo-therapy, in phase I of the study did not significantly increase the incidence and severity of hematological toxicity caused by the adjuvant TMZ-based chemotherapy administered in phase II of the study.
Conclusion: The investigated multimodality treatment regimen was well-tolerated and prolonged survival while improving patients' quality of life.