Potential therapeutic effect of adriamycin-monoclonal anti-prostatic acid phosphatase antibody conjugate on human prostate tumor.

Adriamycin was conjugated to an IgG1 monoclonal antibody specific for human prostatic acid phosphatase via a dextran bridge. The adriamycin-monoclonal antibody conjugate retained substantially the original immunological activity of the antibody. Antitumor effect of the conjugate in vitro was studied by its inhibition on RNA synthesis in human prostate tumor cells (LNCaP), which exhibited a higher inhibition than that by an identically prepared adriamycin-normal mouse IgG conjugate but was less than that by free adriamycin. The loss in pharmacological activity of the conjugate in vitro was proportional to the extent of dextran oxidation. Antitumor effect in vivo demonstrated that adriamycin-monoclonal antibody conjugate greatly inhibited the growth of xenografted prostate tumor, as compared with control groups, only in the early phase of experiment. These results suggested that although adriamycin conjugated to monoclonal anti-PAP antibody via a dextran bridge may be a potential reagent for experimental immunochemotherapy of prostate tumor, caution must be exercised at this stage of development.