Phase I trial of misonidazole (NSC#261037) plus cyclophosphamide in solid tumors.

Abstract

Misonidazole, a hypoxic cell sensitizer, enhances the antitumor effects of cyclophosphamide in preclinical studies. Several studies also showed increased cytotoxicity for normal tissues. We undertook a phase I study of this combination. The regimen consisted of oral administration of misonidazole at one of two dose levels, 1 g/m2 and 2 g/m2, followed by an intravenous (IV) injection of cyclophosphamide four hours later. The cycle was repeated every twenty-one days. The dose of misonidazole remained constant for each regimen, but the dose of cyclophosphamide ranged from 0.4 g/m2 to 1.3 g/m2. Thirty-eight trials in 35 patients with advanced solid tumors were considered evaluable. Dose-limiting toxicity was granulocytopenia at 1 g/m2 of cyclophosphamide without significant thrombocytopenia or anemia. Peripheral neuropathy was negligible. Two patients received cumulative doses of 8 and 16 g/m2 of misonidazole without neurotoxicity. One patient developed hemorrhagic cystitis. Nausea and vomiting was mild to moderate. Possible evidence of tumor stabilization was seen in three patients, and one patient had a mixed response. The mean serum half-life for misonidazole was 11.3 hours (range, 8.4 to 20.0) and for cyclophosphamide 8.3 hours (range, 3.2 to 15.5), both within the previously reported ranges. In conclusion, it appears that this combination is well tolerated and that misonidazole does not significantly potentiate myelotoxicity caused by cyclophosphamide or alter its pharmacokinetics. The recommended starting doses for misonidazole and cyclophosphamide in phase II trials using this schedule of administration should be 2 g/m2 and 1 g/m2, respectively, with escalation for cyclophosphamide to individual tolerance.

Application of New Radiosensitizer Based on Nano-Biotechnology in the Treatment of Glioma

“…DNA double-strand repair inhibitors (DSBRIs) KU55933 were once considered as one of the most promising drugs to improve radiotherapy, but its clinical application remains due to its potential toxicity to normal tissues, inability to select-enter tumor cells, and poor solubilization ( 28 ). Misonidazole is a hypoxic cell sensitizer, which can enhance the antitumor effects of cyclophosphamide in preclinical studies ( 29 ). Formerly, it is expected to be an ideal radiotherapy sensitizer in terms of controlling radiation-resistant tumor cells and p53 mutant tumor cells ( 30 ).…”