Pharmacokinetics of mitomycin-C in plasma and tumor tissue of cervical cancer patients and in selected tissues of female rats

Abstract

Mitomycin-C (MMC) is an alkylating agent which has shown significant activity in gynecologic cancers, both in vivo and in vitro. We determined the delivery of MMC to target tissue by comparing plasma and tumor tissue concentrations of MMC as measured by high-performance liquid chromatography (HPLC) in five patients with cervical cancer. In a companion study, we measured MMC concentrations in plasma and selected tumors of female rats given an equivalent dose. In patients, the mean terminal half-life and total body clearance rates of MMC were 40 min and 275 ml/min/m 2, respectively. The mean cervical tumor to plasma concentration of MMC was 1.26 ± 0.34 (mean ± SE, n = 4). In female rats, the terminal half-life and total body clearance rates of MMC were 28.4 min and 270 ml/min/m 2, respectively. Tissue concentrations of MMC in rats were lower than plasma concentrations measured at corresponding times. The highest concentrations were found in lung and uterus (including cervix) with lower concentrations in ovary and liver. The mean half-life for elimination of MMC from tissues of rats was 20.3 ± 2.8 min (mean ± SE, n = 6). Based on similar pharmacokinetic parameters in rats and patients, the rat appears to be a suitable model for the disposition of MMC in human patients. The near equivalent drug concentrations found in tumor and plasma of patients suggests that the in vitro tests conducted at concentrations based on plasma level may be relevant to cervical tumor tissue, as well.