[meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] sulfatoplatinum(II)--pharmacokinetic studies

The maximally attainable level of the non-plasma protein bound fraction of a single 10.0 mumol/kg i.p. dose of [meso-1,2-bis(2,6-dichloro-4-hydroxyphenyl)ethylenediamine] sulfatoplatinum(II), a drug active on the murine, hormone-sensitive MXT-M-3.2 breast cancer, lies markedly below the concentration causing a significant cytotoxic effect on a cell line derived from this tumor. This result confirms our opinion that the strong in vivo activity of this drug on hormone-sensitive breast cancers is mediated by its estrogenic potency by analogy with high dosed steroidal and non-steroidal estrogens. A specific cytotoxic effect utilizing the estrogen receptor as carrier, as formerly postulated, is unlikely.