Activity of [1,2-di(cyclopentadienyl)-1,2-di(p-N,N-domethylaminophenyl)-ethanediyl] titanium dichloride against tumor colony-forming units

[1,2-di(cyclopentadienyl)-1,2-di(p-N,N-dimethylamino-phenyl)-ethanediyl] titanium dichloride is a newly synthesized transition metal-based anti-cancer drug. We studied the anti-tumor activity of this drug (final concentrations: 25, 250 and 2500 mu mol/l) against freshly explanted human tumors, using an in vitro soft agar cloning system. A total of eight tumor samples were evaluated using 1-h exposures. Additionally, the breast carcinoma cell line MCF-7 was examined with regard to sensitivity. The tested compound was markedly active against one renal cancer sample, whereas other renal tumors were resistant. Concentration-dependent anti-tumor activity was demonstrated for all samples except for melanoma. At concentrations of 250 mu mol/l or less, the compound was less active than cisplatin or equally active at 0.2 mu g/ml, whereas at 2500 mu mol/l it showed a significant cytotoxic activity against a wide spectrum of tumor types. The highest activity was observed against renal carcinomas (three of three tumor specimens inhibited at 2500 mu mol/l). Sensitivity was also highly remarkable in the breast cancer cell line MCF-7 inhibited in a range of 25-2500 mu mol/l, whereas melanoma cells seemed to be profoundly resistant. Further clinical development of this drug appears warranted because of the broad cytotoxic activity shown.