Comparative studies of taxol and taxotere on tumor growth and lymphocyte functions.

Taxotere, a semisynthetic derivative similar to taxol, has shown promising results in vitro and in preliminary in vivo studies. We have previously reported that taxol at 10 micrograms/ml suppressed the cytotoxic function and activation of natural killer cells and major histocompatibility nonrestricted (MHC-NR) T cells against the ovarian cell line OV-2774 and the erythroleukemia cell line K-562. In this paper, we investigated the effect of taxotere on lymphocyte function and found that a suppression of MHC-NR cytotoxicity of naive lymphocytes is only seen at higher doses of taxotere (50 micrograms/ml). At the concentrations of 10 and 50 micrograms/ml, taxotere did not have any effect on the cytotoxic function of IL-2-preactivated lymphocytes. On the contrary, both taxol and taxotere caused a significant suppression of lymphocyte growth and activation with IL-2 at 10 and 50 micrograms/ml. Both drugs (at the concentration of 10 micrograms/ml) were potent inhibitors of the growth of the tumor cell lines OV-2774 and K-562. In conclusion, despite the fact that taxotere shares with taxol a potent antitumor effect, it seems to be less suppressive for lymphocyte cytotoxicity, an effect clearly desirable in cancer therapy.