Total Body Irradiation and Astatine-211-Labeled BC8-B10 Monoclonal Antibody for the Treatment of Nonmalignant Diseases

OUTLINE: Patients receive astatine At 211 anti-CD45 monoclonal antibody BC8-B10 intravenously (IV) on any day between days -10 and -7, fludarabine IV on days -6 to -2, cyclophosphamide IV over 1 hour on days -6 to -5 and 3 to 4, and thymoglobulin IV over 4-6 hours on days -4 to -2. Patients undergo TBI on day -1 and hematopoietic cell transplant on day 0. Beginning day 5, patients also receive mycophenolate mofetil orally (PO) or IV thrice daily every 8 hours up to day 35 if no GVHD present and sirolimus PO daily until day 365. Patients undergo blood sample collection and may undergo bone marrow aspiration throughout the study. After completion of study treatment, patients are followed up at 1 and 2 years and then periodically for up to 5 years. Note: National Heart, Lung, and Blood Institute (NHLBI) funding for this study ended in 2022.