Successful treatment pure red cell aplasia after ABO major mismatched allogeneic hematopoietic stem cell transplantation with avatrombopag and low dose rituximab

Abstract Background Pure red cell aplasia (PRCA) following allogeneic hematopoietic stem cell transplantation (allo‐HSCT) with ABO major incompatibility is characterized by transfusion dependent anemia. No standard treatment existed for PRCA following allo‐HSCT yet. Study Design and Methods We conducted a retrospective study, and reported our experience with the use of avatrombopag and lower dose rituximab to treat five patients with PRCA subsequent to major ABO‐incompatible allo‐HSCT. Results Five cases of PRCA were identified from 72 patients who underwent allo‐HSCT with major or bidirectional ABO mismatch. Cumulative incidence at Day +60 was 6.9% (5/72) at our center. All donor and recipient blood groups were A + and O + , respectively. In the first three cases we reported, patients received erythropoietin, plasma exchange, and donor lymphocyte infusion, but none of them had any effect. After 4 weeks of treatment with low dose rituximab (100 mg/week) combined with avatrombopag (40 mg/day), favorable outcomes were obtained. According to the aforementioned experience, Cases 4 and 5 were administered low‐dose rituximab and avatrombopag in 3 months after transplantation, and erythroid response was observed on 3 weeks after treatment. Our patients tolerated low‐dose rituximab and avatrombopag well and experienced rapid efficacy, with a median duration of 3 weeks. Furthermore, no severe infection or thrombocytosis necessitated a dose adjustment. Conclusion Low‐dose rituximab and avatrombopag may be an effective treatment for patients with PRCA after major ABO‐incompatible allo‐HSCT. The patients should be treated at least 90 days post transplantation if conventional erythropoietin therapy fails.