INTRAARTERIAL THERAPY OF HUMAN GLIOMA XENOGRAFTS IN ATHYMIC RATS USING 4-HYDROPEROXYCYCLOPHOSPHAMIDE

The addition of chemotherapy, notably using nitrosoureas, in the treat ment of patients with glioblastoma multiforme has resulted in only mod est improvements in long-term patient survival over the use of surgica l intervention and irradiation alone. Intraarterial (i.a.) chemotherap y offers the potential benefit of increasing tumor drug delivery becau se of first-pass drug uptake, while minimizing systemic drug levels an d toxicity. We have now investigated the i.a. therapy of intracerebral human glioma xenografts in athymic rats with 4-hydroperoxycyclophosph amide (4-HC), a preactivated derivative of cyclophosphamide. Athymic m ale rats were given intracerebral injections of the human glioma line D-54 MG. On Day 5 after injection, the rats were randomized (n = 8-10) by body weight (mean weight. approximately 300 g). In one set of expe riments, each group received either i.v. saline, i.a. saline, 6 mg i.a . 4-HC, 6 mg i.v. 4-HC (6 mg), or 12 mg i.v. 4-HC. Intraarterial 4-HC produced significant increases in median survival (Day 24) compared wi th i.a. saline controls (140% increase), equivalent doses given i.v. ( 71% increase), and twice the equivalent dose given i.v. (50% increase) (by Wilcoxon rank sum analysis, P < 0.05 is statistically significant ). The i.a. maximum tolerated dose was subsequently determined to be a pproximately 12.5 mg in non-tumor-bearing rats. Further experiments de monstrated a dose-response increase in survival for i.a. dosages of 6, 9, and 12.5 mg with significant improvement when compared with saline controls and 12.5 mg i.v. Pharmacokinetic experiments also demonstrat ed a significant first-pass uptake advantage for i.a. (versus i.v.) ad ministered 4-HC. The short plasma half-life and marked antiglioma acti vity of 4-HC, without the need for hepatic activation, suggest a thera peutic application of this drug in the i.a. treatment of brain tumors.