Preliminary experimental results with the nitrosourea derivative ACNU in the treatment of malignant gliomas

Comparative studies were carried out to evaluate the cytotoxic effectiveness of the nitrosureas ACNU (Nimustine) and BCNU (Carmustine) at equitoxic dose levels in xenografts from two astrocytomas grades III/IV (Li, Re) and one oligodendroglioma grade III (Oe) on nude mice. Growth delay was measured as the endpoint. All tumours were characterized initially and at regular intervals in later passages as to their histomorphologic pattern, expression of glial fibrillary acid protein and DNA-content by means of flow cytometry. These characteristics were shown to be unchanged in our xenografts over more than 27 passages. Growth delays of 18.7 days (ACNU) and 2.4 days (BCNU) for the Li-xenograft (p less than 0.01) were observed at an LD10 for both drugs. For the Re- and Oe-xenografts, growth delays of 18.0 vs. 14.0 days (p less than 0.001) and greater than 27.0 vs. 14.2 days (p less than 0.02) were observed at an equitoxic dose of 33 mg/kg ACNU or BCNU i.p., respectively. These preclinical data suggest a therapeutic advantage with ACNU for these high grade gliomas and should encourage further experimental and clinical investigations.