Ether lipids enhance the cytotoxic effect of teniposide and paclitaxel in liposomes against leukaemic cells in culture.

This study investigated the relevance of combining lipophilic anti-cancer drugs intercalated into the phospholipid bilayer of liposomes. The cytotoxic interaction of two ether lipids, octadecylphosphocholine and ET-18-OCH3, and the chemotherapeutic drugs teniposide and paclitaxel on cancer cells in vitro was evaluated by use of a combined tetrazolium/formazan-labelled thymidine assay. Summation was calculated by the fractional product method. Enhanced cytotoxic activity was found with combinations of the ether lipids with both teniposide and paclitaxel against leukaemic cells. Combination of teniposide and paclitaxel showed antagonism. The benefit of the liposomal formulation form for the ether lipids was supported by the fact that their haemolytic activity was much reduced when they were incorporated into liposomes.