Antitumor efficacy of taxane liposomes on a human ovarian tumor xenograft in nude athymic mice

Taxanes such as paclitaxel (Taxol) and docetaxel (Taxotere) are promising agents for use against ovarian cancer and other malignancies. Recently, SB‐T‐1011, a semisynthetic taxane, has been prepared from 14‐hydroxy‐10‐deacetylbaccatin III. SB‐T‐1011 shows similar or greater in vitro cytostatic activity than paclitaxel, depending on the tumor cell line. The administration of taxanes is problematic due to their low solubility in most pharmaceutically acceptable solvents; formulations used clinically contain Cremophor/ethanol (diluent 12) or polysorbate 80/ethanol, excipients which may cause serious adverse effects. To eliminate these vehicles, we have prepared paclitaxel liposome formulations. The objective of the present work was to evaluate the antitumor activity of paclitaxel and two semisynthetic analogs in Cremophor‐based and liposomal formulations. Antitumor activity was evaluated against A121a, a taxane‐sensitive human ovarian tumor, growing as subcutaneous xenografts in athymic nude mice. Free and liposomal formulations of each taxane showed similar antitumor effect. The antitumor activity of paclitaxel and SB‐T‐1011 was similar, and docetaxel was more potent than either paclitaxel or SB‐T‐1011. Overall, taxane liposomes were better tolerated and more easily administered iv than taxane formulated in Cremophor/ethanol.