461 International Journal of HEMATOLOGY A Diagnostic Dilemma in Stem Cell Transplantation for β-Thalassemia Major: Progressive Loss of Take Or Pure Red Cell Aplasia? Giuseppe Visani, Moira Lucesole, Giuliana Leopardi, Barbara Guiducci, Claudio Giardini, Alessandro Isidori Hematology and Hematopoietic Stem Cell Transplant Centre, San Salvatore Hospital, Pesaro, Italy Received April 5, 2007; received in revised form July 31, 2007; accepted August 10, 2007 Int J Hematol. 2007;86:461-462. doi: 10.1532/IJH97.E0718 © 2007 The Japanese Society of Hematology Letter to the Editor Allogeneic stem cell transplantation (allo-SCT) for major thalassemia patients may be complicated by a relevant rejection rate varying, according to the risk classes and the conditioning regimens, from 15% to 35% [1]. Furthermore, rejection is particularly frequent in those thalassemic patients who receive a conditioning regimen with less than 200 mg/kg of cyclophosphamide for a risk class III, as previ- ously demonstrated by this Institution [2]. The rejection often appears as a progressive loss of take, as shown by the progressive donor cells reduction in chimerism assays. For all these reasons, when observing a progressive reduction of the erythropoietic function in this setting of patients, the first diagnosis could be in favor of a partial graft failure. This “poor graft function” diagnosis often leads to correction with a further allogeneic stem cell infusion with possible danger- ous consequences (eg, graft-versus-host disease [GvHD]). Moreover, the stem cell donor (eg, voluntary unrelated donor [VUD]) may not be available for a second stem cell collection. Another possibility is that thalassemic patients submitted to allo-SCT may develop pure red cell aplasia (PRCA) after allo-SCT. Due to the relevant frequency of rejection observed in thalassemia major patients submitted to transplant, the distinction between the possible loss of the take and the development of a PRCA may thus engender a diagnostic dilemma. Although PRCA may recover spontaneously, it frequently requires therapy. The appropriate treatment of PRCA is still unclear. Nevertheless, PRCA could be refractory to more than one therapeutic option. It has recently been demon- strated that rituximab (Mabthera, Roche, Switzerland) can be effective in several immune-mediated syndromes [3,4]. Moreover, there is increasing evidence that rituximab may be useful in the treatment of immune-mediated disorders, such as PRCA occurring after lymphoproliferative disorders or ABO-incompatible allo-SCT [5-7]. However, no data are so far available about the efficacy of rituximab in patients developing PRCA after ABO-incompatible allo-SCT for tha- lassemia major. Herewith we report the case of a 23-year-old male patient who received a transplantation from an ABO incom- patible (donor B Rh+; recipient 0 Rh+), HLA-identical VUD for β-thalassemia major. He received a standard mye- loablative conditioning regimen for allo-SCT in β-tha- lassemia major, according to the GITMO (Gruppo Italiano Trapianto Midollo Osseo) guidelines (busulfan, 16 mg/kg, day –10 to –7; cyclophosphamide, 120 mg/kg, days –5 and –6; thiotepa, 10 mg/kg, day –6). The GvHD prophylaxis consisted of: cyclophosphamide, 7.5 mg/kg (day +1 after allo-SCT), short course methotrexate, 10 mg/m 2 (days +3, +11), and cyclosporin A (CsA). The CsA dosage was initially 5 mg/kg per day, then reduced to 3 mg/kg per day at day +6, and gradually tapered until it was stopped on day +365. The donor’s bone marrow was red cell depleted due to donor/recipient blood group mismatch. A total of 2.5 × 10 8 /kg nucleated cells, 2.9 × 10 6 /kg CD34 + cells, and 0.157 × 10 8 /kg CD3 + cells were infused. After the transplant, the hematolog- ical recovery was incomplete (Figure 1). The patient was sup- ported with 0 positive red blood cells (RBCs) (3-5 RBC units/week) and platelets transfusions (1-2 apheresis/week); he also received granulocyte colony-stimulating factor peri- odically. In addition, he received 10,000 units of erythropoietin every other day starting from day +100, with- out significant benefit. On day +190 anti-B titer was high (1:512), and was reduced to 1:16 after 3 consecutive plasma- phereses. However, we did not observe any hematological improvement. Cytomegalovirus, Epstein-Barr virus, anti- human herpesvirus 6, anti-human herpesvirus 8, and par- Correspondence and reprint requests: Giuseppe Visani, MD, Hematology and Hematopoietic Stem Cell Transplant Centre, San Salvatore Hospital, Via Lombroso, 61100 Pesaro, Italy; 39-0721 364039; fax: 39-0721 364036 (e-mail: g.visani@ospedalesansalvatore.it).