[Enhancement of antitumor activity of mitomycin C against human breast carcinoma xenografts by pretreatment with KM 2210].

Three human breast carcinoma xenografts, MCF-7, R-27 and T-61 serially transplanted into nude mice were treated with mitomycin C (MMC) alone, KM2210 (estra-1, 3, 5(10)-triene-3, 17 beta-diol, 3 benzoate 17-[4-(4-bis(2-chloroethyl)amino)phenyl)-1-oxobutoxy)acetate) alone and KM2210 followed by MMC. One hundred or 300 mg of KM2210 per kg were administered orally daily from Day 1 to 4 and MMC at the dose of 3 mg/kg was given ip on Day 5. The antitumor activity of MMC on these xenografts was enhanced by pretreatment with KM2210, suggesting a new combination chemo- and endocrine therapy of hormone-dependent human breast carcinomas.