TARGETED DELIVERY OF DIPHTHERIA-TOXIN VIA IMMUNOLIPOSOMES - EFFICIENTANTITUMOR-ACTIVITY IN THE PRESENCE TOXIN ANTIBODIES

Diphtheria toxin (DT) has attracted considerable attention for anti-ca ncer therapy. However, its extensive use is prohibited by (i) its non- specific action which can result in substantial toxicity, (ii) most pa tients have low serum levels of anti-DT antibodies (AT antibodies) whi ch can inactivate DT and (iii) its immunogenicity will boost the circu lating AT antibody level, thereby further compromising the antitumor a ctivity. To overcome these limitations, we have developed a new approa ch for targeted delivery of DT utilizing immunoliposomes. In this appr oach, protection against the non-specific action of DT is combined wit h efficient antitumor activity even in the presence of inactivating AT antibodies.