[Tumor inhibition by metallocenes: effect of titanocene, zirconocene, and hafnocene dichlorides on Ehrlich ascites tumor in mice (author's transl)].

The antitumor activity of the metallocene dichlorides TDC, ZDC, and HDC against Ehrlich ascites tumor in CF1 mice is investigated. A single i.p. injection of TDC in the optimum dose (30-60 mg/kg) 24 h p.t.t. achieves survival of 80-90% of the animals until day 180 p.t.t. without any tumor manifestation. This indicates an increase in the mean survival time of about 900% referred to the untreated animals. In contrast, ZDC and HDC exhibit no recognizable antineoplastic properties under equal experimental conditions. Assuming a similar mechanism of tumor inhibition for both DDP and the antineoplastic active metallocene dichlorides TDC, VDC, and MDC the comparatively increased non bonding Cl...Cl distance ("bite") of ZDC and HDC may be responsible for cancerostatic inactivity of the latter compounds.