High-dose ⁹⁰Y Mx-diethylenetriaminepentaacetic acid (DTPA)-BrE-3 and autologous hematopoietic stem cell support (AHSCS) for the treatment of advanced breast cancer: A phase I trial 1

This Phase I trial explores the use of high-dose ⁹⁰Y conjugated to the antibreast cancer monoclonal antibody BrE-3 and autologous hematologic cell support in the treatment of women with stage four breast cancer. Nine women with heavily pretreated disease were enrolled. All of the patients had BrE-3-positive tumors by immunostaining and were treated with increasing doses of ⁹⁰Y (15 mCi/m², 3 patients), 20 mCi/M² (six patients), and a fixed (50 mg) dose of BrE-3.¹¹¹ In-labeled BrE-3 (5 mCi) was given simultaneously for scanning purposes. The only toxkity noted was hematological. Grade 4 platelet toxicity requiring transfusion support occurred in four patients. Grade 4 WBC toxicity was seen in two patients that resolved in 3-9 days. All hematological nadirs occurred approximately 25 days after treatment Objective partial responses were noted in 4 of 8 (50%) patients with measurable tumors. Dose escalation is ongoing.