Effect of anti-B16 melanoma monoclonal antibody on established murine B16 melanoma liver metastases.

The administration of anti-B16 monoclonal antibody of the IgG2b isotype to mice bearing established B16 melanoma liver metastases caused a significant and consistent reduction of up to 90% in the number of these metastases. No reduction in the number of metastases was noted when antigenically unrelated tumor or nonspecific immunoglobulin were employed. The antibody-mediated antitumor effect was completely abrogated by total body irradiation of the host. Treatment of the tumor-bearing host with antiserum directed against asialo GM1 prior to anti B16 antibody administration, abrogated the therapeutic effect indicating the involvement of a radiosensitive, ASGM1-positive cell in the tumor regression. The antitumor effect of the antibody treatment could be augmented by the concomitant administration of recombinant interleukin-2. The effect seen may have possible application in the treatment of liver metastases in humans by combined immunotherapy using recombinant interleukin-2 and specific antitumor monoclonal antibodies.