A Phase I Trial of Pre-Surgical O6-Benzylguanine in the Treatment of Patients With Malignant Glioma

OBJECTIVES:

• Determine the dose of O6-benzylguanine (O6-BG) that produces total depletion of tumor O6-alkylguanine-DNA alkyltransferase (AGT) levels in more than 90% of patients with cerebral anaplastic astrocytoma or glioblastoma multiforme.
• Determine the qualitative and quantitative toxicities of O6-BG in this patient population.

OUTLINE: This is a dose escalation study.

Part I: The first cohort of 10 patients receives O6-benzylguanine (O6-BG) IV over 1 hour at dose level 1 beginning 6 hours prior to surgery. If at least 3 of 10 patients in the first cohort have detectable levels of O6-alkylguanine-DNA alkyltransferase (AGT), then a second cohort of 10 patients receives O6-BG as above at dose level 2. Dose escalation continues until at least 8 of 10 patients have undetectable AGT activity. At this point, 4 additional patients are accrued. If at least 11 of 14 patients at this dose level have undetectable levels of AGT, then this dose level constitutes the biologic modulatory dose of O6-BG. If less than 11 of 14 patients have undetectable levels of AGT, then 10 additional patients are treated at a higher dose. If at any time 3 or more patients at a dose level have detectable AGT activity, accrual is stopped at that dose level and patients are treated at the next higher dose level. (Part I closed to accrual effective 7/10/2000)

Part II: An additional cohort of 14 patients receives O6-BG at dose level 5 beginning 18 hours prior to surgery.