Preclinical evaluation of a new anthracycline derivative, SM-5887 by subrenal capsule assay

SM-5887, a new totally synthetic anthracycline derivative was evaluated the antitumor activity by subrenal capsule assay (SRCA) and the activity was compared to that of doxorubicin. The method of SRCA was the same originally developed by Bogden et al and 200 mg/kg of bredinin was administered subcutaneously 3 times every 2 days in order to induce immunosuppression of mice. Mice were given a single intravenous dose of either 30 mg/kg of SM-5887 or 15 mg/kg of doxorubicin. Fourty-four cases out of 64 were evaluable in this assay. The mean tumor growth inhibition rate (TGIR) in either SM-5887 or doxorubicin group was similar and the TGIRs of these two groups correlated well (y = 10.4 + 0.67x, p less than 0.01). Using more than 50% decrease of TGIR to define "sensitive", the chemosensitivity rates of SM-5887 and doxorubicin were 23% (10/44) and 25% (11/44) respectively. SM-5887 was effective to sarcomas and ovarian cancer especially. These results suggest that SM-5887 might have a similar antitumor activity compared to doxorubicin in clinical use.