Tumor inhibition by titanocene complexes: activity against sarcoma 180

The antitumor activity of various titanocene derivatives was examined against ascitic and solid, subcutaneously growing sarcoma 180. The complexes investigated were two dihalide compounds, (C5H5)2TiCl2 (I) and (C5H5)2TiBr2 (II), two carboxylato complexes, (C5H5)2Ti (cis-OOCCH = CHCOOH)2(III) and (C5H5)2Ti(OOCCCl3)2(IV), and the p-aminothiophenolate hydrochloride (C5H5)2Ti(p-SC6H4NH3+Cl-)2(V). Against ascitic sarcoma 180, best results were obtained for I; an injection of 50 mg/kg resulted in the survival of 40-50% of the animals (ILS, 161-184%). A similar result was recorded for cis-diamminedichloroplatinum(II), whereas the compounds II-IV induced a maximum cure rate of 20% (ILS, 95-139%). Against solid sarcoma 180, triple injections of I-V caused reduction of mean tumor weight to 23-53% of control values, the dichloro complex I exhibiting most pronounced activity. These results clearly underline antitumor potency for titanocene complexes (C5H5)2TiX2 modified at the acido ligand X.