Anti-Cd45 Radioimmunotherapy Followed By Haploidentical Allogeneic Hematopoietic Cell Transplantation For Advanced Acute Leukemia Or High-Risk Mds

Background: Although hematopoietic cell transplantation (HCT) may offer the best chance for cure for patients with relapsed/refractory hematologic malignancies, many of these patients will relapse after HCT. Escalating doses of total body irradiation (TBI) or chemotherapy prior to HCT can decrease relapse, but incurs higher toxicity, resulting in no survival benefit. Therefore, there is a need to reduce relapse without increasing the toxicity of the conditioning regimen prior to HCT. In addition, many potentially curable candidates for HCT do not have a fully human leukocyte antigen (HLA) matched donor. This is an especially challenging hurdle for many ethnic minority patients, yet nearly all patients have a related donor identical for one HLA haplotype (i.e., haploidentical). Radioiodinated anti-CD45 radioimmunotherapy (RIT) has been shown to deliver high-doses of radiation specifically to hematolymphoid organs, while sparing normal tissues. We report a phase I/II study using iodine-131 (131I)-anti-CD45 antibody (BC8) combined with pre- and post-transplant cyclophosphamide, and reduced intensity conditioning prior to haploidentical HCT.