Preclinical antitumor activity of two novel taxanes

Two taxane analogs, BMS-184476 and -188797, were evaluated for their in vitro cytotoxicity and in vivo antitumor activity, and compared with paclitaxel and occasionally docetaxel (Taxotere).

Cytotoxicity was assessed in vitro using a panel of human tumor cell lines. Several different murine and human tumor models were used in vivo to evaluate the taxane analogs.

Both compounds were found to have cytotoxic potency similar to paclitaxel and to partially overcome two different forms of paclitaxel resistance. BMS-184476 was found to be clearly superior to paclitaxel in three human xenograft tumor models: A2780 ovarian carcinoma; HCT/pk, a moderately paclitaxel-resistant colon carcinoma; and L2987 lung carcinoma. Additionally, in the clinically derived TAXOL-unresponsive ovarian carcinoma, HOC79, BMS-184476 performed slightly better than paclitaxel and Taxotere. BMS-184476 and paclitaxel were inactive in two murine model systems, M5076 sarcoma and the paclitaxel-resistant M109/txlr lung carcinoma. Against the parental M109 tumor, both BMS-184476 and paclitaxel performed comparably. BMS-184476 was never found to be inferior to paclitaxel. The other taxane analog, BMS-188797, displayed efficacy superior to paclitaxel in four in vivo tumor models: HOC79, HCT/ pk, M109, and L2987 carcinomas. Like paclitaxel and BMS-184476, BMS-188797 was inactive versus M5076 sarcoma.

Two new taxane analogs were characterized as superior to paclitaxel or Taxotere in several in vivo tumor models. Both BMS-184476 and -188797 are currently in phase I or II clinical trials.