Reduction of HLA antibodies by bi-specific antibody blinatumomab

Donor specific antibodies against human leukocyte antigen (HLA) can cause engraftment failure in hemopoietic stem cell transplantation, or antibody mediated rejection in solid organ transplantation. To increase the chance of successful transplants, donor specific antibodies have to be reduced or depleted in patients with high levels of HLA antibodies. However, no current therapies have been proven to remove or reduce HLA antibodies effectively in the majority of patients. Blinatumomab, a bi-specific antibody, is used as a treatment for B-cell acute lymphoblastic leukemia (ALL) by targeting B cells. To determine if blinatumomab can reduce HLA antibodies, we tested HLA antibodies pre- and post-blinatumomab treatment in 7 B-ALL patients who had HLA antibodies. We found that 6 of 7 patients showed a substantial reduction in HLA antibodies after blinatumomab infusion. Calculated Panel Reactive Antibody (cPRA), a measurement of the possibility of getting immunologically compatible donors, was also lowered after blinatumomab infusion. Our observation suggests that blinatumomab can be a potential drug for desensitization therapy.