Allogeneic hematopoietic stem-cell transplantation remains the only curative treatment for patients with acquired severe aplastic anemia (SAA). When a matched sibling is not available, one can search for a matched unrelated donor or a cord blood unit (CB) in the international registries or, more recently, for an HLA haploidentical (HAPLO) family member. International guidelines call for a course of antithymocyte globulin (ATG) and cyclosporine before a patient with SAA receives a transplant from a donor other than an HLA identical sibling, but whether this is necessary for patients age <20 years is less clear. Here I will examine the rapid increase in HAPLO transplantations for SAA, showing encouraging early results both in children and young adults. Graft-versus-host disease prophylaxis remains of primary importance in patients with SAA, and in vivo T-cell depletion with either ATG or alemtuzumab offers a significant survival advantage. Finally, I will discuss the strong age effect, which is particularly evident at >40 and 50 years of age for reasons not entirely clear and which should be taken into account when designing a treatment strategy for a given patient.

Acquired aplastic anemia (AA) is an immune-mediated bone marrow aplasia that is strongly associated with clonal hematopoiesis upon marrow recovery. More than 70% of AA patients develop somatic mutations in their hematopoietic cells. In contrast to other conditions linked to clonal hematopoiesis, such as myelodysplastic syndrome (MDS) or clonal hematopoiesis of indeterminate potential in the elderly, the top alterations in AA are closely related to its immune pathogenesis. Nearly 40% of AA patients carry somatic mutations in the PIGA gene manifested as clonal populations of cells with the paroxysmal nocturnal hemoglobinuria phenotype, and 17% of AA patients have loss of HLA class I alleles. It is estimated that between 20% and 35% of AA patients have somatic mutations associated with hematologic malignancies, most characteristically in the ASXL1, BCOR, and BCORL1 genes. Risk factors for evolution to MDS in AA include the duration of disease, acquisition of high-risk somatic mutations, and age at AA onset. Emerging data suggest that several HLA class I alleles not only predispose to the development of AA but may also predispose to clonal evolution in AA patients. Long-term prospective studies are needed to determine the true prognostic implications of clonal hematopoiesis in AA. This article provides a brief, but comprehensive, review of our current understanding of clonal evolution in AA and concludes with 3 cases that illustrate a practical approach for integrating results of next-generation molecular studies into the clinical care of AA patients in 2018.

Since the approval of horse antithymocyte globulin (ATG) decades ago, there was a long hiatus in therapies with activity in severe aplastic anemia (SAA). This scenario changed in 2014 when eltrombopag, a thrombopoietin receptor agonist, was approved for SAA after an insufficient response to initial immunosuppressive therapy (IST). The basis for this approval was the observation of single-agent activity of eltrombopag in this patient population, where 40% to 50% recovered blood counts at times involving >1 lineage. The achievement of transfusion independence confirmed the clinical benefit of this approach. Increase in marrow cellularity and CD34+ cells suggested a recovery to a more functioning bone marrow. Further in its development, eltrombopag was associated with standard horse ATG plus cyclosporine in first line, producing increases in overall (at about 90%) and complete response rates (at about 40%) and leading to transfusion independence and excellent survival. Interestingly, best results were observed when all drugs were started simultaneously. The cumulative incidence of clonal cytogenetic abnormalities to date has compared favorably with the vast experience with IST alone in SAA. Longer follow-up will help in define these long-term risks. In this review, the development of eltrombopag in SAA will be discussed.

Immune-mediated hemocytopenia is a common cytopenic diseases without bone marrow hematopoietic abnormalities, the patient's quality of life is significantly reduced when first-line treatments are ineffective. Rapamycin, possesses a clear mechanism of targeting mTOR protein, can upregulate regulatory T cells and induces apoptosis of specific cells, by regulating the lymphocyte subsets, so as to treat various types of immune-mediated hemocytopenia with a certain therapeutic effect. In this reviews, the action mechanism and clinical application of rapamycin in immune thrombocytopenia（ITP）, autoimmune hemolytic anemia（AIHA）, acquired aplastic anemia and autoimmune lymphoproliferative syndrome（ALPS） etc. are summarized.

Güngör A, Yaralı N, Fettah A, Ok-Bozkaya İ, Özbek N, Kara A. Hereditary spherocytosis: Retrospective evaluation of 65 children. Turk J Pediatr 2018; 60: 264-269. Hereditary spherocytosis (HS) is a common cause of congenital hemolytic anemia in Caucasians and it could be diagnosed at any age. The aim of this study is to examine the demographic characteristics, clinical features and laboratory findings of children with HS and their complications observed during follow up. Sixty-five patients, with hereditary spherocytosis between January 2008 and September 2013, were enrolled into this retrospective study. The age of patients at the time of diagnosis varied between 15 days and 17 years. The median age of patients at diagnosis was 48 months (IQR 2-78). The female/male ratio was 1.1. Forty-seven patients (72.3%) had a family history of HS. The patients were classified according to laboratory findings: 13 of them (20%) were diagnosed as mild HS, 36 (55.4%) as moderate HS and of 16 (24.6%) as severe HS. During follow-up, nine patients (13.8%) experienced an aplastic crisis. Megaloblastic crisis was not observed in any patient. Twenty patients (30.8%) had cholelithiasis. Splenectomy was performed in 20% of patients and the mean age for splenectomy was 8.3 years. Complications such as sepsis or thrombosis were not detected after splenectomy. Hereditary spherocytosis should be kept in mind in patients with anemia, jaundice and splenomegaly and the family history must be questioned. The most common complication was gallstone; even patients without severe hemolysis should be followed intermittently by abdominal ultrasonography in order to control the development of gallstone.

We report on a 16-year-old Japanese boy in whom an esophageal squamous cell carcinoma (ESCC) developed 12 years after allogeneic hematopoietic stem cell transplantation was performed for aplastic anemia. A high frequency of microsatellite instability was detected in samples of ESCC. Moreover, the detection of pathogenic variants, including single nucleotide substitution of TP53 (c.346C>T) and BRCA2 (c.6952C>T) and splicing of KDM6A (c.1194+2T>G), suggest that the development of ESCC in the patient was triggered by impairment of checkpoint and repair for DNA damage and epigenetic modification through accumulation of gene mutations induced by chronic graft-versus-host disease and prolonged administration of tacrolimus.

Objective: To explore the expression of SLAMF6 on CD8(+) T cells in patients with severe aplastic anemia (SAA) and its correlation with disease immune status. Methods: By flow cytometry (FCM), SLAMF6 expression level in peripheral blood CD8(+) T cells was detected in 21 patients with SAA and 15 normal controls respectively from February 2017 to April 2018. The correlation between SLAMF6 expression level and hematopoietic functions, including HGB, PLT, the neutrophil granulocyte and reticulocyte absolute value in peripheral blood, hyperplasia degree (percentage of granulocytes, erythrocytes, lymphocytes and megakaryocytes in bone marrow) and perforin, granzyme B, IFN-γ expression level in CD8(+) T cells were evaluated. To further confirm the effect of SLAMF6 on CD8(+) T cells, anti-SLAMF6 Ab was used to block SLAMF6 pathway (IgG as control), and FCM was used to detect the perforin, granzyme B, and IFN-γ production of CD8(+) T cells. Results: The expression of SLAMF6 on CD8(+) T cells in untreated SAA patients[(56.29±12.97)%]was significantly lower than that of normal controls[(80.96±7.36)%](t=-7.672, P<0.001). The expression of SLAMF6 on CD8(+) T cells in SAA patients were positively correlated with the HGB, PLT, the neutrophil granulocyte and reticulocyte absolute value in peripheral blood, percentage of granulocytes, erythrocytes in bone marrow (all P<0.05), but they were negatively correlated with the percentage of lymphocytes in bone marrow, and the expression of perforin, granzyme B, and IFN-γ of CD8(+) T cells (all P<0.05). After blocking SLAMF6 pathway by anti-SLAMF6 Ab, the expression levels of perforin, granzyme B and IFN-γ in SAA patients were significantly higher than those in the untreated group, and the differences were statistically significant (all P<0.05). Conclusions: SLAMF6 is significantly down-regulated on CD8(+) T cells in SAA patients, which may act as a negative immunoregulatory molecule participating in the mechanism of SAA by affecting the functional molecules secretion on CD8(+) T cells.

Objective: To explore the efficacy and safety of haploidentical hematopoietic stem cell transplantation (Haplo-HSCT) for paroxysmal nocturnal hemoglobinuria (PNH). Methods: A total of 17 patients with PNH who received Haplo-HSCT from January 2013 to September 2017 were analyzed retrospectively. Results: Of them, 4 patients had de novo PNH, 13 patients had aplastic anemia-PNH syndrome (AA-PNH). All patients received modified busulfan and Cytoxan (BuCy)-based regimens combined with anti-thymocyte globulin (ATG). Granulocyte colony-stimulating factor-mobilized bone marrow and peripheral blood stem cells were transplanted as graft. Prophylaxis for graft-versus-host disease (GVHD) was ciclosporin A+ mycophenolate mofetil (MMF)+short-term methotrexate (MTX). All patients were engrafted successfully. The median time of neutrophils to 0.5×10(9)/L and platelets to 20×10(9)/L was 12(10-15) days and 14(11-45) days, respectively. All of the 17 patients achieved full donor chimerism at 30 d after Haplo-HSCT. Seven patients developed grade Ⅱ-Ⅳ acute GVHD, and 4 chronic GVHD. Median follow-up time was 27.1 (8.6-60.4) months. Of the 17 patients, 15 survived and 2 died of severe pulmonary infection and transplant associated thrombotic microangiopathy. Three-year overall survival was (77.8±15.2)%. Conclusion: Haplo-HSCT may be effective and safe for PNH patients who did not have matched donor.