Antitumor effect of adriamycin entrapped in liposomes conjugated with monoclonal antibody against tumor-associated antigen of bovine leukemia cells.

Monoclonal antibody against tumor-associated antigen (TAA) expressed on bovine leukemia cells was conjugated to liposomes containing adriamycin (ADM), and the specificity and therapeutic effects of the conjugates were examined in vitro and in vivo using a TAA-positive bovine leukemia cell line as the target tumor. In vitro studies with the TAA-positive cell line clearly indicated that the antibody-conjugated liposomes containing ADM exerted selective effects on TAA-positive cells in the inhibition assay of 3H-thymidine incorporation. Three injections of liposomes containing ADM (4 mg/kg) into tumor-bearing nude mice significantly inhibited the tumor growth and the therapeutic effect of the antibody-conjugated liposomes was far greater than that of normal mouse IgG-conjugated liposomes as assessed in terms of tumor size.