Tumor inhibition by titanocene complexes: influence on xenografted human adenocarcinomas of the gastrointestinal tract.

The present study deals with the influence of some bis(eta 5-cyclopentadienyl)titanium(IV) (titanocene) complexes, mainly represented by titanocene dichloride, on the development of several human gastrointestinal (GI) carcinomas (one stomach, seven colon, four sigmoid, and two rectal adenocarcinomas), all xenografted to athymic mice. In 10 of these 14 carcinomas, titanocene dichloride effected growth suppression of greater than 50% in comparison with control tumors. In the case of the stomach and two colon adenocarcinomas, absolute decreases in tumor volume occurred during and after the treatment period, resulting in growth delays of 6, 14, and 31 days, respectively. No sensitivity dependence was observed in the degree of tumor differentiation. The findings of the present study confirm the tumor-inhibiting activity of titanocene complexes against human GI adenocarcinomas. These results are noteworthy in view of previous clinical and experimental experience indicating that human adenocarcinomas of the stomach and colon are generally rather insensitive to common cytostatic agents.