INTRATUMOR ADMINISTRATION OF FUSOGENIC LIPOSOMES CONTAINING FRAGMENT-A OF DIPHTHERIA-TOXIN SUPPRESSES TUMOR-GROWTH

Previously, we reported that experimental i.p. administration of fusog enic liposomes containing fragment A of diphtheria toxin (DTA) complet ely regressed ascites tumors without ally severe side effects. In this study, we examined the therapeutic effects of intratumor injection of fusogenic liposomes using ddY mice implanted with Sarcoma-180 (S-180) cells intradermally. Intratumor injections of fusogenic liposomes con taining DTA significantly inhibited the tumor growth as assessed by th e relative mean tumor volume, and by the survival time of the mice. No therapeutic effects were observed when simple liposomes containing DT A or empty fusogenic liposomes were administered. Using [H-3]inulin en capsulated in fusogenic liposomes as a marker, we demonstrated that fu sogenic liposomes delivered their contents into the solid tumor cells about 15 times more efficiently than simple liposomes. These results s uggest that intratumor administration of fusogenic liposomes containin g DTA is a highly effective approach to the local treatment of solid t umors.