Antibody-mediated Specific Binding and Cytotoxicity of Liposome-entrapped Doxorubicin to Lung Cancer Cells in Vitro1

Liposome entrapment of doxorubicin has been shown to reduce its cardiotoxicity in vivo and increase its therapeutic index. A further im provement in therapeutic index could be achieved through targeting of liposome-entrapped drug selectively to cancer cells. Monoclonal anti bodies against the squamous lung cancer cell line KI N 205 have been ligated to the surface of long-circulating (Stealth) and conventional liposomes. The antibody-bearing liposomes showed specific, competi tive uptake by KLN-205 cells as compared to liposomes bearing non specific isotype-matched antibodies or antibody-free liposomes. Doxorubicin-containing antibody-liposomes resulted in as much as a 15-fold decrease in the 50% inhibitory concentration for doxorubicin against KLN-205 cells as compared to free doxorubicin or doxorubicin en trapped in antibody-free liposomes.