Successful treatment of refractory pure red cell aplasia with eltrombopag after ABO-incompatible allogeneic hematopoietic stem cell transplantation.

Pure red cell aplasia (PRCA) is a well-recognized complication of ABO major mismatched allogeneic hematopoietic stem cell transplantation (allo-HSCT), with a reported incidence of 10%-20% (Zhidong et al., 2012; Busca et al., 2018). It is clinically characterized by anemia, reticulocytopenia, and the absence of erythroblasts in a normal-appearing bone marrow biopsy (Shahan and Hildebrandt, 2015). The mechanism for PRCA has been presumed to be persistence of recipient isoagglutinins, produced by residual host B lymphocytes or plasma cells, which can interfere with the engraftment of donor erythroid cells (Zhidong et al., 2012). Several risk factors of PRCA at presentation are known, such as presence of anti-A isoagglutinins before transplantation, reduced intensity conditioning, absence of acute graft-versus-host disease (GVHD), sibling donors, and cyclosporin A (CsA) as GVHD prophylaxis (Hirokawa et al., 2013). PRCA is not considered to be a barrier to HSCT, as some patients can recover spontaneously or benefit from various approaches including high-dose steroids, erythropoietin (EPO), plasma exchange, immunoadsorption, donor lymphocyte infusion (DLI), treatment with rituximab, bortezomib, or daratumumab, and tapering or discontinuation of immunosuppression (Hirokawa et al., 2013; Bathini et al., 2019). However, there are still some patients who fail to respond even to aggressive treatment; they become red cell transfusion-dependent and iron-overloaded, and their life quality is impaired.