ANTITUMOR EFFECT OF MITOXANTRONE-CONTAINING LIPOSOMES

The antitumor activity of mitoxantrone-containing liposomes was compar ed in vitro and in vivo with that of free mitoxantrone using L1210 leu kemia cells. The in vitro inhibition of the tumor cells was tested aft er treatment for 24 and 72 h. It was found that mitoxantrone-containin g liposomes showed a slower antitumor reaction and higher antitumor ac tivity after treatment of the cells for 72 h. This was attributed to t he liposomes sustained and enhanced the action of mitoxantrone. The in vivo antitumor effect of L1210 bearing mice treated with either mitox antrone-containing liposomes or free mitoxantrone demonstrated no sign ificant difference in survival time. However, an increase in survival rate for mitoxantrone-containing liposomes was shown. After a high dos e treatment of the tumor bearing mice with mitoxantrone-containing lip osomes, the survival rate was increased. This was due to the increase of antitumor activity and reduction of toxicity of mitoxantrone by lip osomes.