Successful treatment of refractory red cell aplasia after allogeneic hematopoietic cell transplantation with daratumumab

Pure red cell aplasia (PRCA) is an uncommon complication secondary to ABO mismatched allogeneic stem-cell transplantation (allo-HSCT). The best approach for PRCA after allo-HSCT remains unclear. We aim to report a single case with refractory PRCA post-ABO mismatched allo-HSCT resolved with daratumumab. A 34-year-old male diagnosed with aplastic anemia in March 2014 received a peripheral blood reduced-intensity allo-HSCT from an HLA-matched related donor in July 2016. Donor and recipient blood groups were AB positive and 0 positive, respectively, indicating a major ABO incompatibility. The patient was diagnosed with PRCA 2 months after allo-HSCT. After failing multiple standard lines of treatment, compassionate treatment with daratumumab was requested. After receiving six doses of daratumumab, the patient had a marked reticulocyte response and consecutively become transfusion independent. In conclusion, Daratumumab is a human IgG1κ monoclonal antibody targeting CD38 and is used to treat multiple myeloma. The use of anti-CD38 therapy with daratumumab to target residual host plasma cells is safe and effective, and it can be considered in refractory recipients with PRCA after allo-HSCT secondary to ABO incompatibility.