Antitumor activity of peplomycin against 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors

Antitumor activity of peplomycin (PEP) against 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary tumors was compared with activities of bleomycin (BLM) and doxorubicin (adriamycin, ADM). Drugs were administered subcutaneously 3 times weekly (24 times in total) starting on 75 days after an intravenous administration of DMBA. PEP strongly inhibited the growth of mammary tumors detected at the start of the treatment, and some of the tumors disappeared and regressed upon the administration of PEP. The number of stable tumors was larger and the number of progressed tumors smaller in the PEP-treated group than in the control group. Moreover, PEP exhibited strong growth inhibitory effect with slight delay of tumor appearance against mammary tumors appeared during the treatment period. These antitumor effects of PEP were greater than those of BLM, a parent compound of PEP, and almost comparable to those of ADM.