Therapy Trials in Cancer Patients Using an Improved 3-Step Pretargeting Approach

Three-step monoclonal antibody tumor targeting using the avidin-biotin system has been successfully applied to the detection of a variety of solid tumors. We have adopted the same protocol in a pilot therapy trial introducing the therapeutic radionuclide yttrium-90 (Y-90). Eleven patients with various tumors were administered with Y-90 doses ranging from 1.85 to 5.55 GBq. Treatment was well tolerated and no acute toxicity was observed. One patient with brain tumor achieved over 50% regression while another showed a total regression of one of his metastases. Overall 4 out of 11 pts are still in partial remission 1–5 months after therapy. The work is still in progress, however, these preliminary data are encouraging and warrant further studies.