A phase II trial of arsenic trioxide and temozolomide in combination with radiation therapy for patients with malignant gliomas.

Standard treatment for GBM is radiation (RT) and temozolomide (TMZ). Arsenic trioxide (ATO) is synergistic with RT based on several mechanisms of action previously identified, however not tested herein. The MTD of ATO, RT and TMZ was determined in a Phase I trial. We now present the combined Phase I/II data. Patients with newly diagnosed malignant gliomas were eligible for treatment. Patients were treated with RT (60 GY), TMZ (75 mg/m2 daily × 42 days) and ATO 0.20 mg/kg daily in week 1 then twice a week ×5 weeks, after completing RT they were treated with TMZ 5/28 for up to 12 months. MRIs were performed every 8 weeks. A total of 42 patients were enrolled in both the Phase I and II trials for this study treatment. Of the 42 enrolled patients (24 M and 18 W) the median age was 54 (24-80) and median KPS 90 (60-100). 28 patients had a GBM and 14 had anaplastic glioma (AG). All patients completed RT/TMZ/ATO and went on to maintenance TMZ. Median number of post RT cycles of TMZ was 4 (0-12). Median PFS was 7 m for GBM and 75 m for AG and median OS was 17 m for GBM and NR for AG. Best response was CR in 2, SD in 28, PR in 5 and PD in 7. There were no unexpected adverse events. Grade 3 toxicities likely attributable to ATO included prolonged Qtc (n = 1), elevated liver enzymes (n = 2 for ALT/n = 1 for AST) and elevated bilirubin (n = 1). Adding ATO to RT and TMZ is feasible with no increased side effects. The addition of arsenic did not improve overall survival in the GBM patients as compared to historic data. MGMT status was analyzed in 20 of the 42 patients where tissue was available for retrieval and MGMT testing.