Unrelated bone marrow transplantation for beta-thalassemia patients: The experience of the Italian Bone Marrow Transplant Group

Finding a balance in reduced toxicity hematopoietic stem cell transplantation for thalassemia: role of infused CD3+ cell count and immunosuppression

We performed a retrospective analysis on 124 patients with transfusion-dependent thalassemia who were registered in the German pediatric registry for stem cell transplantation. All patients underwent first allogeneic hematopoietic stem cell transplantation (HSCT) between 2011 and 2020 and belonged mainly to Pesaro risk class 1-2. Four-year overall (OS) and thalassemia-free survival (TFS) were 94.5% ± 2.9% and 88.0% ± 3.4% after treosulfan-fludarabine-thiotepa- and 96.9% ± 3.1% (P = 0.763) and 96.9% ± 3.1% (P = 0.155) after busulfan-fludarabine-based conditioning. Mixed chimerism below 75% occurred predominantly in treosulfan-based regimens (27.5% versus 6.2%). OS and TFS did not differ significantly between matched sibling, other matched family and matched unrelated donor (UD) HSCTs (OS: 100.0%, 100.0%, 96.3% ± 3.6%; TFS: 96.5% ± 2.4%, 90.0% ± 9.5%, 88.9% ± 6.0%). However, mismatched UD-HSCTs performed less favorable (OS: 84.7% ± 7.3% (P = 0.029); TFS: 79.9% ± 7.4% (P = 0.082)). We generated a scoring system reflecting the risk to develop mixed chimerism in our cohort. The main risk-reducing factors were a high CD3+ cell count (≥6 × 107/kg) in the graft, busulfan-conditioning, pre-conditioning therapy and low-targeted ciclosporin A trough levels. Acute GvHD grade III-IV in treosulfan-based concepts predominantly occurred in patients with UD and reduced GvHD prophylaxis but not in the context of high CD3+ cell doses. Taken together, this information might be used to develop more risk-adapted HSCT regimens for thalassemia patients.

Αlpha-thalassemia: A practical overview

α-Thalassemia is an inherited blood disorder characterized by decreased synthesis of α-globin chains that results in an imbalance of α and β globin and thus varying degrees of ineffective erythropoiesis, decreased red blood cell (RBC) survival, chronic hemolytic anemia, and subsequent comorbidities. Clinical presentation varies depending on the genotype, ranging from a silent or mild carrier state to severe, transfusion-dependent or lethal disease. Management of patients with α-thalassemia is primarily supportive, addressing either symptoms (eg, RBC transfusions for anemia), complications of the disease, or its transfusion-dependence (eg, chelation therapy for iron overload). Several novel therapies are also in development, including curative gene manipulation techniques and disease modifying agents that target ineffective erythropoiesis and chronic hemolytic anemia. This review of α-thalassemia and its various manifestations provides practical information for clinicians who practice beyond those regions where it is found with high frequency.

Haploidentical transplant for paediatric patients with severe thalassaemia using post-transplant cyclophosphamide and methotrexate: A prospectively registered multicentre trial from the Bone Marrow Failure Working Group of Hunan Province, China

Haploidentical transplantation strategies for patients with transfusion-dependent thalassaemia (TD-TM) remain to be investigated. In this study, 54 paediatric patients with TD-TM were treated with a novel approach using post-transplant cyclophosphamide (PTCy) and low-dose methotrexate (LD-MTX), following a myeloablative regimen. The incidence of neutrophil and platelet engraftment was 96.3% ± 2.6% and 94.4% ± 3.1% respectively. The cumulative incidence of grades II-III acute graft-versus-host disease (GVHD) was 13.8% ± 4.8% at 100 days. At three years, the cumulative incidence of chronic GVHD was 28.5% ± 8.5%. With a median follow-up of 520 days (132-1325 days), the overall survival (OS) and event-free survival (EFS) were 98.1% ± 1.8% and 90.7% ± 3.9% respectively. Compared with the low-dose cyclophosphamide (CTX) conditioning regimen (120 mg/kg), the high-CTX regimen (200 mg/kg) achieved a higher incidence of stable engraftment (100% vs 66.7% ± 15.7%, p = 0.003), a comparable incidence of grades II-III acute GVHD, a lower incidence of chronic GVHD (20.2% ± 8.3% vs 66.6% ± 19.2%, p = 0.011), and better overall survival (100% vs 88.9% ± 10.5%, p = 0.025) as well as EFS (95.6% ± 3.1% vs 66.7% ± 15.7%, p = 0.008). Our results using unmanipulated haploidentical grafts and PTCy with LD-MTX in TD-TM are encouraging. (chictr.org.cn ChiCTR1800017969).

Thalassemia-free and graft-versus-host-free survival: outcomes of hematopoietic stem cell transplantation for thalassemia major, Turkish experience

We report the national data on the outcomes of hematopoietic stem cell transplantation (HSCT) for thalassemia major (TM) patients in Turkey on behalf of the Turkish Pediatric Stem Cell Transplantation Group. We retrospectively enrolled 1469 patients with TM who underwent their first HSCT between 1988 and 2020 in 25 pediatric centers in Turkey. The median follow-up duration and transplant ages were 62 months and 7 years, respectively; 113 patients had chronic graft versus host disease (cGVHD) and the cGVHD rate was 8.3% in surviving patients. Upon the last visit, 30 patients still had cGvHD (2.2%). The 5-year overall survival (OS), thalassemia-free survival (TFS) and thalassemia-GVHD-free survival (TGFS) rates were 92.3%, 82.1%, and 80.8%, respectively. cGVHD incidence was significantly lower in the mixed chimerism (MC) group compared to the complete chimerism (CC) group (p < 0.001). In survival analysis, OS, TFS, and TGFS rates were significantly higher for transplants after 2010. TFS and TGFS rates were better for patients under 7 years and at centers that had performed over 100 thalassemia transplants. Transplants from matched unrelated donors had significantly higher TFS rates. We recommend HSCT before 7 years old in thalassemia patients who have a matched donor for improved outcomes.

Conditioning Regimens in Patients with β-Thalassemia Who Underwent Hematopoietic Stem Cell Transplantation: A Scoping Review

The success of transplant procedures in patients with beta-thalassemia major (β-thalassemia) goes hand-in-hand with improvements in disease knowledge, better supportive care, discoveries in immunogenetics, increase in stem cell sources, and enhancement of conditioning regimens. The aim of this scoping review was to report the evolution of conditioning regimes for β-thalassemia hematopoietic stem cell transplantation. We performed a systematic search for all relevant articles published before July 2021, using the following Medical Subject Headings: "bone marrow transplantation", "stem cell transplantation", "allogeneic", "thalassemia", "β-thalassemia", and "thalassemia major". The final analysis included 52 studies, published between 1988 and 2021, out of 3877 records. The most common conditioning regimen was a combination of busulfan and cyclophosphamide, with successive dose adjustments or remodulation based on patient characteristics. Pre-transplant treatments, reductions in cyclophosphamide dosage, or the adoption of novel agents such as treosulphan all improved overall survival and thalassemia-free survival in transplant-related mortality high-risk patients. Conditioning regimes were modulated for those without a suitable fully matched sibling or unrelated donor, with encouraging results. Hematopoietic stem cell transplantation with haploidentical donors is currently available to virtually all patients with β-thalassemia. However, disparities in outcome are still present around the world. In developing and limited-resource countries, where most diagnoses are focused, transplants are not always available. Therefore, more efforts are needed to close this treatment gap.

HSCT remains the only cure for patients with transfusion-dependent thalassemia until gene therapy strategies are proven to be safe

Patients with β-thalassemia suffer from severe anemia, iron overload and multiple complications, that affect their quality of life and well-being. Allogeneic hematopoietic stem cell transplantation (HSCT) from an HLA-matched sibling donor, performed in childhood, has been the gold standard for thalassemic patients for decades. Unfortunately, siblings are available only for the minority of patients. Fully matched unrelated donors have been the second choice for cure, with equal results as far as overall survival is concerned, having though the cost of frequent and serious complications. On the other hand, haploidentical transplantation is performed more frequently during the last decade, with promising results. Gene therapy represents a novel therapeutic approach, with impressive results from clinical trials, both from gene addition strategies, as well as from the emerging gene editing tools. After reviewing current critical points of HSCT using alternative donors and assessing recently reported safety issues of gene therapy methods, we conclude that, although a breakthrough, the safety of gene therapy remains to be established.

Improving outcomes and quality of life for patients with transfusion-dependent β-thalassemia: recommendations for best clinical practice and the use of novel treatment strategies

INTRODUCTION

β-thalassemia is one of the most common inherited monogenic diseases. Many patients are dependent on a lifetime of red blood cell (RBC) transfusions and iron chelation therapy. Although treatments have a significant impact on quality of life (QoL), life expectancy, and long-term health outcomes have improved in recent decades through safer RBC transfusion practices and better iron chelation strategies. Advances in the understanding of the pathology of β-thalassemia have led to the development of new treatment options that have the potential to reduce the RBC transfusion burden in patients with transfusion-dependent (TD) β-thalassemia and improve QoL.

AREAS COVERED

This review provides an overview of currently available treatments for patients with TD β-thalassemia, highlighting QoL issues, and providing an update on current clinical experience plus important practical points for two new treatments available for TD β-thalassemia: betibeglogene autotemcel (beti-cel) gene therapy and the erythroid maturation agent luspatercept, an activin ligand trap.

EXPERT OPINION

Approved therapies, including curative gene therapies and supportive treatments such as luspatercept, have the potential to reduce RBC transfusion burden, and improve clinical outcomes and QoL in patients with TD β-thalassemia. Cost of treatment is, however, likely to be a significant barrier for payors and patients.

Outcomes of allogeneic transplantation for hemoglobin Bart's hydrops fetalis syndrome in Hong Kong

BACKGROUND

Hemoglobin Bart's hydrops fetalis syndrome (BHFS) was once considered a fatal condition universally. Medical advances over the past three decades have resulted in increasing numbers of BHFS survivors. This retrospective review summarized local territory-wide experience and outcomes of BHFS patients who received allogeneic hematopoietic stem cell transplantation (HSCT) in Hong Kong.

METHODS

All BHFS patients who underwent allogeneic HSCT in Hong Kong, either in one of the two former pediatric transplant centers (Queen Mary Hospital and Prince of Wales Hospital) on or before 2019 or in the single territory-wide pediatric transplant center (Hong Kong Children's Hospital) since 2019, from January 1, 1996, till December 31, 2020, were included. Basic demographic data, perinatal history, transplant details, long-term outcomes, and morbidities were reviewed.

RESULTS

Total five allogeneic HSCT were performed in two males and three females at a median age of 22 months, which include one 8/8 matched-sibling bone marrow transplant, one 5/6 matched-sibling cord blood transplant with HLA-DR antigenic mismatch, two 12/12 matched-unrelated peripheral blood stem cell transplant (PBSCT), and one haploidentical PBSCT with TCRαβ/CD45RA depletion from maternal donor. Neutrophil and platelet engrafted (>20 × 10⁹ /L) at a median of 15 and 22 days, respectively. All achieved near full donor chimerism at 1 month. All patients survived and remained transfusion-independent without significant morbidities with median follow-up duration of 10 years.

CONCLUSION

To conclude, local data demonstrated favorable outcome of allogeneic HSCT for BHFS patients, but sample number is small. Non-directive approach in counseling and international collaboration is recommended.

Repeated CD45RA-depleted DLI successfully increases donor chimerism in a patient with beta-thalassemia major after haploidentical stem cell transplant

Allogeneic hematopoietic stem cell transplantation is curative for transfusion-dependent thalassemia, but mixed chimerism (MC) may herald graft rejection. We report a child who failed bone marrow transplant (BMT) from matched unrelated donor (MUD) successfully salvaged with haploidentical peripheral blood stem cell transplant (PBSCT), but had MC in T-lymphocyte compartment despite near-complete donor chimerism in myeloid compartment. MC was successfully improved by repeated CD45RA-depleted donor lymphocyte infusion (DLI). A 2-year-old Chinese girl with beta-thalassemia major underwent 12/12-MUD BMT with HU/AZA/Cy/Flu/Bu/TT conditioning resulted in graft rejection. As donor refused second donation, rescue haploidentical PBSCT was performed with alemtuzumab/fludarabine/treosulfan conditioning. Harvest product was CD3/CD45RA depleted with extra products cryopreserved. Split cell chimerism performed 1-month after haplo-transplant showed 97% mother, 3% MUD, and 0% host for granulocytes but 38% mother, 62% MUD, and 0% host for CD3 + T cells. In view of low haploidentical donor chimerism in T-lymphocyte compartment, CD45RA-depleted DLI using cryopreserved product was performed on day + 38, after thymoglobulin 3 mg/kg given as T-cell depletion 3 days beforehand. T-cell chimerism improved to 51% mother and 49% MUD post-DLI. Second cryopreserved CD45RA-depleted DLI was given 17 days after the first DLI (day + 55), and 100% full chimerism of mother's T cells was gradually established without significant graft-versus-host disease (GVHD) or viral reactivation. To conclude, split lineage chimerism determination is beneficial to guide management strategy. For MC in T-cell compartment, CD45RA-depleted DLI is a potential alternative to unselected T cells as it carries lower risk of GVHD and infection.

Graft-versus-host Disease Prophylaxis With Abatacept Reduces Severe Acute Graft-versus-host Disease in Allogeneic Hematopoietic Stem Cell Transplant for Beta-thalassemia Major With Busulfan, Fludarabine, and Thiotepa

BACKGROUND

We hypothesized that the addition of 4 doses of abatacept to our standard acute graft-versus-host disease (GVHD) prophylaxis would reduce the incidence of day +100 severe acute GVHD in children with transfusion-dependent beta-thalassemia major undergoing a myeloablative allogeneic hematopoietic stem cell transplant (HSCT), without impacting engraftment.

METHODS

Twenty-four children with beta-thalassemia major received abatacept at a dose of 10 mg/kg intravenously on days -1, +5, +14, and +28 after HSCT in addition to calcineurin inhibitors and methylprednisolone. Outcomes were compared to 8 beta-thalassemia patients who received standard acute GVHD prophylaxis.

RESULTS

There was no difference in engraftment between the 2 groups. No patient had grades III-IV acute GVHD by day +100 in the abatacept cohort compared with 50% in the standard acute GVHD prophylaxis group (P = 0.001). Viral reactivation occurred in 5 children in the standard acute GVHD cohort and in 20 children in the abatacept cohort (P = 0.2). Thalassemia-free survival after HSCT was 100% in the abatacept cohort compared to 62.5% in the standard cohort at last follow-up (P = 0.007).

CONCLUSIONS

Adding abatacept to our routine GVHD prophylaxis reduced the incidence of day +100 severe acute GVHD without impacting engraftment or survival.

Double-unit unrelated cord blood transplantation for thalassemia major: Comparison with HLA-identical sibling bone marrow transplantation

UCBT recipients with TM are at high risk of EF related to low number of stem cells and prior alloimmunization after multiple blood transfusions. Here, we evaluated the safety and efficacy of double-unit UCBT using TT-containing conditioning regimens in TM. Retrospective analysis of children who underwent double-unit UCBT for TM in the Prince of Wales Hospital between August 2007 and January 2017, and outcome of double-unit UCBT for TM was compared with outcome of HLA-matched sibling BMT. Ten patients, median age 4.2 years, received double-unit UCBT. All patients except one engrafted at a median of 19 days. None of the patients with successful engraftment had grade III or IV aGVHD. Among nine patients with successful engraftment, six of nine patients evaluable after day 100 developed cGVHD. All patients with cGVHD were well controlled after treatment with steroids and/or supportive care and maintained good quality of life. In comparison with patients receiving BMT, those given UCBT had slower platelet recovery, and more cGVHD. With a median follow-up of 272 months after BMT and 84 months after UCBT, the 8-year OS after BMT and UCBT was 92% and 90% (P = .84), whereas 8-year DFS after BMT and UCBT was 87% and 80% (P = .54). UCB could be an acceptable source of stem cells for transplantation of TM patients when HLA-matched family bone marrow donors are NA.

Hematopoietic stem cell transplantation for people with β-thalassaemia

BACKGROUND

Thalassaemia is an autosomal recessive blood disorder, caused by mutations in globin genes or their regulatory regions, resulting in a reduced rate of synthesis of one of the globin chains that make up haemoglobin. In β-thalassaemia there is an underproduction of β-globin chains combined with excess of free α-globin chains. The excess free α-globin chains precipitate in red blood cells, leading to their increased destruction (haemolysis) and ineffective erythropoiesis. The conventional treatment is based on the correction of haemoglobin through regular red blood cell transfusions and treating the iron overload that develops subsequently with iron chelation therapy. Although, early detection and initiations of such supportive treatment has improved the quality of life for people with transfusion-dependent thalassaemia, allogeneic hematopoietic stem cell transplantation is the only widely available therapy with a curative potential. Gene therapy for β-thalassaemia has recently received conditional authorisation for marketing in Europe, and may soon become widely available as another alternative therapy with curative potential for people with transfusion-dependent thalassaemia. This is an update of a previously published Cochrane Review.

OBJECTIVES

To evaluate the effectiveness and safety of different types of hematopoietic stem cell transplantation, in people with transfusion-dependent β-thalassaemia.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched online trial registries. Date of the most recent search: 07 April 2021.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials comparing hematopoietic stem cell transplantation with each other or with standard therapy (regular transfusion and chelation regimen).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened trials and had planned to extract data and assess risk of bias using standard Cochrane methodologies and assess the quality using GRADE approach, but no trials were identified for inclusion in the current review.

MAIN RESULTS

No relevant trials were retrieved after a comprehensive search of the literature.

AUTHORS' CONCLUSIONS

We were unable to identify any randomised controlled trials or quasi-randomised controlled trials on the effectiveness and safety of different types of hematopoietic stem cell transplantation in people with transfusion-dependent β-thalassaemia. The absence of high-level evidence for the effectiveness of these interventions emphasises the need for well-designed, adequately-powered, randomised controlled clinical trials.

Identification of New Soluble Factors Correlated With the Development of Graft Failure After Haploidentical Hematopoietic Stem Cell Transplantation

Graft failure is a severe complication of allogeneic hematopoietic stem cell transplantation (HSCT). The mechanisms involved in this phenomenon are still not completely understood; data available suggest that recipient T lymphocytes surviving the conditioning regimen are the main mediators of immune-mediated graft failure. So far, no predictive marker or early detection method is available. In order to identify a non-invasive and efficient strategy to diagnose this complication, as well as to find possible targets to prevent/treat it, we performed a detailed analysis of serum of eight patients experiencing graft failure after T-cell depleted HLA-haploidentical HSCT. In this study, we confirm data describing graft failure to be a complex phenomenon involving different components of the immune system, mainly driven by the IFNγ pathway. We observed a significant modulation of IL7, IL8, IL18, IL27, CCL2, CCL5 (Rantes), CCL7, CCL20 (MIP3a), CCL24 (Eotaxin2), and CXCL11 in patients experiencing graft failure, as compared to matched patients not developing this complication. For some of these factors, the difference was already present at the time of infusion of the graft, thus allowing early risk stratification. Moreover, these cytokines/chemokines could represent possible targets, providing the rationale for exploring new therapeutic/preventive strategies.

Hematopoietic Stem Cell Transplantation in Patients with Hemoglobinopathies

Hemoglobinopathies are the most common single-gene diseases and are estimated to affect millions of people worldwide. Thalassemia and sickle cell disease are the most prevalent diseases of this group. Today, despite the decreasing number of newborns diagnosed with a hemoglobinopathy, it remains an important health problem for many countries. Although regular red blood cell (RBC) transfusions, advanced iron chelation, and supportive therapy alternatives have improved life expectancy, allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative option for patients with hemoglobinopathies to prevent irreversible organ damage. Modern transplantation approaches and careful posttransplantation follow-up of patients have improved survival outcomes, and HSCT has now been performed in several patients with hemoglobinopathies worldwide. Considering current experiences, hematopoietic stem cell transplantation is recommended in cases of β-thalassemia (β-thal) in the presence of a matched family or unrelated donor, without secondary organ damage due to transfusion. In patients with sickle cell anemia, transplantation indications include transfusion dependence and cases of secondary organ damage. Recently, gene therapy as a possible treatment option has yielded promising results, though it is not in routine clinical use at its current stage.

Matched Family versus Alternative Donor Hematopoietic Stem Cell Transplantation for Patients with Thalassemia Major: Experience from a Tertiary Referral Center in South India

Hematopoietic stem cell transplantation (HSCT) is the only curative option available for patients with thalassemia major in India with increasing access to alternate donor transplantation for patients with no matched family donor. We aimed to analyze the impact of family and alternate donor HSCT on morbidity and mortality post-HSCT. We conducted a retrospective study in the department between July 2007 and December 2018 where all children who underwent HSCT for thalassemia major were included. A total of 264 children were included with a median age of 6 years (male/female, 1.4:1). The graft source was matched related donor (MRD) (76%; parent 15%, sibling 85%) and matched unrelated donor (MUD) (22%). All children received a myeloablative conditioning regimen with treosulfan/thiotepa/fludarabine in 93% and busulfan/cyclophosphamide in 7%. The source of stem cells was peripheral blood in 61%, bone marrow in 38%, and umbilical cord blood in 3%. The incidence of bacteremia was 14% versus 25% in MRD versus MUD groups. There was a higher incidence of posterior reversible encephalopathy syndrome (PRES) in the MUD group (10% versus 3%). Engraftment occurred in 97% with a higher trend toward mixed chimerism in the MRD group (12% versus 2%). When indicated, whole-blood donor lymphocyte infusion was used to ensure complete chimerism in children in the MRD group. A statistically significant difference was found in the incidence of graft versus host disease (GVHD), both acute and chronic between the MUD versus MRD groups, 60% versus 20% and 41% versus 17%, respectively (P = .001). Similarly, immune cytopenia and cytomegalovirus reactivation were also significantly higher in the MUD group, 27% versus 1.4% and 25% versus 2%, respectively (P = .001). Thalassemia-free survival in our cohort was 96%, 94%, and 84% with a median follow-up of 65 months in the matched sibling donor, matched family donor, and MUD groups, respectively. Overall survival of 95% and 90% with a median follow-up of 65 months was noted in those who underwent transplantation less than and greater than 7 years of age, respectively. MUD transplantation for patients with thalassemia major involves specific challenges such as PRES and unusual manifestations of GVHD such as immune cytopenia. Early interventions to optimize supportive care and measures to reduce GVHD are required to ensure survival rates of over 90%.

Oridonin enhances γ‑globin expression in erythroid precursors from patients with β‑thalassemia via activation of p38 MAPK signaling

Upregulation of fetal hemoglobin expression can alleviate the severity of β‑thalassaemia. This study aimed to investigate the effects of Oridonin (ORI, a diterpenoid compound) on γ‑globin expression in human erythroid precursor cells and the potential underlying mechanisms. Erythroid precursor cells were enriched from 12 patients with β‑thalassaemia by two‑phase culture. The cells were then treated with different doses of ORI and the survival of erythroid precursor cells was determined. In addition, the expression levels of γ‑globin and potential mechanisms were analyzed by reverse transcription‑quantitative PCR, western blotting and chromatin immunoprecipitation. Treatment with 0.5 µM ORI preferably enhanced γ‑globin expression and exhibited little cytotoxicity. Similar to sodium butyrate (NaB, a histone deacetylase inhibitor), ORI significantly increased p38 mitogen‑activated protein kinase (MAPK) activation, γ‑globin expression, histone H3 and H4 acetylation at the Gγ‑ and Aγ‑globin promoters, and cAMP‑response element binding protein 1 (CREB1) phosphorylation. These effects were significantly mitigated by treatment with SB23580, a p38 MAPK inhibitor, in erythroid precursor cells. Therefore, ORI may effectively enhance γ‑globin expression by activating p38 MAPK and CREB1, leading to histone modification in γ‑globin gene promoters during the maturation of erythroid precursor cells. These findings suggested that ORI may be a novel and potential therapeutic agent for the treatment of β‑thalassaemia.

Unrelated Donor Peripheral Blood Stem Cell Transplantation for Patients with β-Thalassemia Major Based on a Novel Conditioning Regimen

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only available curative treatment for patients with β-thalassemia major (β-TM). However, the problem of finding a suitable sibling donor with well-matched human leukocyte antigens is still a major obstacle to curing these patients. With the progress in high-resolution HLA typing technology and supportive care, outcomes after allogeneic HSCT from an HLA well-matched unrelated donor (UD) now approach those of well-matched sibling donors. However, UD HSCT is hampered by an increased risk of graft-versus-host disease and transplant-related mortality. Here we report the outcome of transplantation in patients with β-TM using a novel WZ-14-TM transplant protocol, based on cyclophosphamide, intravenous busulfan, fludarabine, and antithymocyte globulin, in our center. Forty-eight patients between 2 and 11 years of age with β-TM received HLA well-matched UD peripheral blood stem cell transplantation following the WZ-14-TM protocol. All of the transplanted patients achieved donor engraftment. The incidences of grade II to IV acute and chronic graft-versus-host disease were 8.3% and 8.3%, respectively. The overall survival and thalassemia-free survival rates were both 100%. This encouraging result suggests that the WZ-14-TM protocol is a feasible and safe conditioning regime for patients with β-TM undergoing UD HSCT.

Bone marrow transplantation for adolescents and young adults with sickle cell disease: Results of a prospective multicenter pilot study

We conducted a multicenter pilot investigation of the safety and feasibility of bone marrow transplantation (BMT) in adults with severe sickle cell disease (SCD) (NCT 01565616) using a reduced toxicity preparative regimen of busulfan (13.2 mg/kg), fludarabine (175 mg/m2 ) and thymoglobulin (6 mg/kg) and cyclosporine or tacrolimus and methotrexate for graft-vs-host disease (GVHD) prophylaxis. Twenty-two patients (median age 22 years; range 17-36) were enrolled at eight centers. Seventeen patients received marrow from an HLA-identical sibling donor and five patients received marrow from an 8/8 HLA-allele matched unrelated donor. Before BMT, patients had stroke, acute chest syndrome, recurrent pain events, were receiving regular red blood cell transfusions, or had an elevated tricuspid regurgitant jet (TRJ) velocity, which fulfilled eligibility criteria. Four patients developed grades II-III acute GVHD (18%) and six developed chronic GVHD (27%) that was moderate in two and severe in one patient. One patient died of intracranial hemorrhage and one of GVHD. Nineteen patients had stable donor chimerism, 1-year post-transplant. One patient who developed secondary graft failure survives disease-free after a second BMT. The one-year overall survival and event-free survival (EFS) are 91% (95% CI 68%-98%) and 86% (95% CI, 63%-95%), respectively, and 3-year EFS is 82%. Statistically significant improvements in the pain interference and physical function domains of health-related quality of life were observed. The study satisfied the primary endpoint of 1-year EFS ≥70%. This regimen is being studied in a prospective clinical trial comparing HLA-matched donor BMT with standard of care in adults with severe SCD (NCT02766465).

Bone marrow stromal cells from β-thalassemia patients have impaired hematopoietic supportive capacity

BACKGROUND. The human bone marrow (BM) niche contains a population of mesenchymal stromal cells (MSCs) that provide physical support and regulate hematopoietic stem cell (HSC) homeostasis. β-Thalassemia (BT) is a hereditary disorder characterized by altered hemoglobin beta-chain synthesis amenable to allogeneic HSC transplantation and HSC gene therapy. Iron overload (IO) is a common complication in BT patients affecting several organs. However, data on the BM stromal compartment are scarce.

METHODS. MSCs were isolated and characterized from BM aspirates of healthy donors (HDs) and BT patients. The state of IO was assessed and correlated with the presence of primitive MSCs in vitro and in vivo. Hematopoietic supportive capacity of MSCs was evaluated by transwell migration assay and 2D coculture of MSCs with human CD34⁺ HSCs. In vivo, the ability of MSCs to facilitate HSC engraftment was tested in a xenogenic transplant model, whereas the capacity to sustain human hematopoiesis was evaluated in humanized ossicle models.

RESULTS. We report that, despite iron chelation, BT BM contains high levels of iron and ferritin, indicative of iron accumulation in the BM niche. We found a pauperization of the most primitive MSC pool caused by increased ROS production in vitro which impaired MSC stemness properties. We confirmed a reduced frequency of primitive MSCs in vivo in BT patients. We also discovered a weakened antioxidative response and diminished expression of BM niche–associated genes in BT-MSCs. This caused a functional impairment in MSC hematopoietic supportive capacity in vitro and in cotransplantation models. In addition, BT-MSCs failed to form a proper BM niche in humanized ossicle models.

CONCLUSION. Our results suggest an impairment in the mesenchymal compartment of BT BM niche and highlight the need for novel strategies to target the niche to reduce IO and oxidative stress before transplantation.

FUNDING. This work was supported by the SR-TIGET Core grant from Fondazione Telethon and by Ricerca Corrente.

Unrelated and related donor transplantation for beta-thalassemia major: A single-center experience from India

Hematopoietic stem cell transplantation (HSCT) remains the only curative treatment in patients with β-thalassemia major. A matched sibling or a related donor is usually found in only 25%-30% of the patients. There are limited data on matched unrelated donor (MUD) transplants from India. We reviewed HSCT outcome in 56 children with TM who underwent 57 transplants at our center. Related donor (RD) (n=43) and MUD (n=14) transplants were performed with TreoFluT-based conditioning regimen in majority (95%) of patients. Peripheral blood stem cells (PBSC) were the preferred (85%) source of stem cells. The overall survival (OS) at 1 year in RD and MUD groups was 87.6±5.2% and 85.7±9.4% at a median follow-up of 25 (1-92) months and 22.5 (1-50) months, respectively (P=.757). The thalassemia-free survival (TFS) at 1 year was 87.6±5.2% and 77.1±11.7% with a median follow-up of 24 (1-92) and 16.5 (1-50) months, respectively (P=.487). Although acute (14% vs 64%) and chronic graft-versus-host disease (GVHD) (13.9% vs 42.9%), infectious (39.5% vs 71.4%), and non-infectious (37.2% vs 78.5%) complications are higher in MUD transplant group, the present data show a comparable OS and TFS among RD and MUD group with treosulfan-based regimen using PBSC grafts.

Genetic Therapies for Sickle Cell Disease

Sickle cell disease is the most prevalent monogenic disorder worldwide and curative therapies are limited to hematopoietic stem cell transplant to the few with matched donors. Gene therapy has curative potential, whereby autologous hematopoietic stem cells are genetically modified and transplanted, which would not be limited by matched donors, resulting in 1-time, life-long correction devoid of immune side effects. Significant progress has been made to clinically translate gene therapy for sickle cell disease using lentivirus vectors carrying antisickling genes. This review focuses on the current state of the field, factors that determine clinical success, gene editing, and future prospects.

Unrelated Donor Transplantation in Children with Thalassemia using Reduced-Intensity Conditioning: The URTH Trial

Allogeneic hematopoietic stem cell transplantation (HSCT) can cure transfusion-dependent thalassemia (TDT). In a multicenter trial we investigated the efficacy of reduced-intensity conditioning (RIC) before unrelated donor (URD) HSCT in children with TDT. Thirty-three children, ages 1 to 17 years, received bone marrow (BM) or umbilical cord blood (UCB) allografts. Median time to neutrophil engraftment was 13 days (range, 10 to 25) and 24 days (range, 18 to 49) and platelet engraftment 23 days (range, 12 to 46) and 50 days (range, 31 to 234) after BM and UCB allografts, respectively. With a median follow-up of 58 months (range, 7 to 79), overall and thalassemia-free survival was 82% (95% CI, .64% to .92%) and 79% (95% CI, .6% to .9%), respectively. The cumulative incidence of grades II to IV acute graft-versus-host disease (GVHD) after BM and UCB allografts was 24% and 44%; the 2-year cumulative incidence of chronic extensive GVHD was 29% and 21%, respectively; 71% of BM and 91% of UCB recipients discontinued systemic immunosuppression by 2 years. Six patients who had Pesaro risk class 2 (n = 5) and class 3 (n = 1) died of GVHD (n = 3), viral pneumonitis (n = 2) and pulmonary hemorrhage (n = 1). Outcomes after this RIC compared favorably with URD HSCT outcomes for TDT and supported engraftment in 32 of 33 patients. Efforts to reduce GVHD and infectious complications are being pursued further.

Gene Therapy and Genome Editing

The β-thalassemias are inherited blood disorders that result from insufficient production of the β-chain of hemoglobin. More than 200 different mutations have been identified. β-Thalassemia major requires life-long transfusions. The only cure for severe β-thalassemia is to provide patients with hematopoietic stem cells. Globin gene therapy promises a curative autologous stem cell transplantation without the immunologic complications of allogeneic transplantation. The future directions of gene therapy include enhancement of lentiviral vector-based approaches, fine tuning of the conditioning regimen, and the design of safer vectors. Progress in genetic engineering bodes well for finding a cure for severe globin disorders.

Is the Benefit-Risk Ratio for Patients with Transfusion-Dependent Thalassemia Treated by Unrelated Cord Blood Transplantation Favorable?

Transfusion-dependent thalassemia (TDT) is an inherited disorder characterized by absent or defective production of α- or β-hemoglobin chains. If untreated, the disease invariably culminates in death in early infancy due to cardiac failure or overwhelming infection. Although there is clear evidence of good health-related quality of life and return to normal life style, the choice to undergo hematopoietic stem cell transplantation (HSCT) remains a challenge because of the potential risk of transplant-related mortality (TRM) in TDT. Successful hematopoietic stem cell transplantation may cure the hematological manifestations of TDT, but introduces risks of TRM and morbidity. The low incidence of graft-versus-host disease (GVHD) provides the major rationale for pursuing unrelated cord blood transplantation (CBT). Considerable evidence suggests a lower rate of recurrence after CBT than after transplantation from adult donors. As the TRM, overall survival, and thalassemia-free survival for CBT improve, the utility of this stem cell source will expand to indications that have hitherto rarely used unrelated CBT. This paper summarizes the current progress in understanding the advances in unrelated CBT for thalassemia. Although as yet only in a limited number of patients, the results of unrelated CBT for thalassemia are encouraging.

Thalassemia Major: Transplantation or Transfusion and Chelation

Thalassemia is the most common monogenic hematologic disease that affects millions in the world and kills thousands of patients every year. Without transfusion or transplantation, patients with thalassemia major are expected to die within months of diagnosis. However, long-term transfusion and chelation therapy is highly challenging for many developing countries where the disease is prevalent, representing a major and unsustainable health burden. Stem cell transplantation is the only cure for thalassemia. It has witnessed major developments that have made it less toxic, more successful, and feasible for a larger number of patients with diverse comorbidities and from a wider range of donors. Advances in human leukocyte antigen typing have greatly refined alternate donor selection with results of matched unrelated donors similar to matched sibling donors. Novel strategies such as haploidentical and cord blood transplantation have increased the possibility of patients with no healthy donor to get a better opportunity to survive and avoid chronic transfusion complications. Cost-effectively, transplantation should be considered the primary treatment of choice in the presence of a suitable related or unrelated donor and at centers with a satisfactory experience in the field of transplantation and particularly, in managing those with thalassemia. Despite some complications such as graft-versus-host disease and late conditioning effects, the overall improvement in the quality of life of thalassemia is difficult to deny. Unfortunately, the number of transplants for thalassemia represents only a minority of all transplants conducted globally and the essential requirement for transplants for thalassemia in limited-resources countries should mandate the transplant societies, including Worldwide Network for Blood and Marrow Transplantation, to collaborate to help initiate and support specialized transfusion and transplant programs for managing thalassemia.

Hematopoietic cell transplantation: Training challenges and potential opportunities through networking and integration of modern technologies to the practice setting

Hematopoietic cell transplantation (HCT), particularly allogeneic HCT, is a complex and a high-risk procedure requiring expertise to manage potential treatment complications. Published data supports the value of quality management systems in improving post-transplant outcomes; however, there are no universally established, or agreed upon, criteria to assess adequacy of training of physicians, transplant or nontransplant, and supporting staff, among others. It is of paramount importance for transplant centers to identify the needed area(s) of expertise in order to seek appropriate training for their staff. Moreover, transplant physicians need to keep up-to-date with the rapidly occurring advances in the field. Outcomes of patients undergoing HCT are affected by various factors related to patient, disease, procedure, preventative, and supportive strategies, among others. Accordingly, availability of databases is necessary to collect information on these variables and use to benchmark future prospective clinical trials aiming at further improving clinical outcomes. Twinning with leading centers worldwide is helping to not only bridge the survival gap of patients diagnosed with cancer in the developing vis-à-vis the developed world, but eventually closing it. The advent of the World Wide Web and revolution in telecommunication has made access to information more readily available to various sectors including healthcare. Telemedicine is enabling healthcare delivery to remote and underserved geographic areas. In the setting of HCT, ensuring compliance to prescribed therapies and post-transplant surveillance are some areas where implementing telemedicine programs could fulfill an unmet need.

Bone Marrow Homing and Engraftment Defects of Human Hematopoietic Stem and Progenitor Cells

Homing of hematopoietic stem cells (HSC) to their microenvironment niches in the bone marrow is a complex process with a critical role in repopulation of the bone marrow after transplantation. This active process allows for migration of HSC from peripheral blood and their successful anchoring in bone marrow before proliferation. The process of engraftment starts with the onset of proliferation and must, therefore, be functionally dissociated from the former process. In this overview, we analyze the characteristics of stem cells (SCs) with particular emphasis on their plasticity and ability to find their way home to the bone marrow. We also address the problem of graft failure which remains a significant contributor to morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Within this context, we discuss non-malignant and malignant hematological disorders treated with reduced-intensity conditioning regimens or grafts from human leukocyte antigen (HLA)-mismatched donors.

Cyclophosphamide improves engraftment in patients with SCD and severe organ damage who undergo haploidentical PBSCT

Peripheral blood stem cell transplantation (PBSCT) offers a curative option for sickle cell disease (SCD). Although HLA-matched sibling transplantation is promising, the vast majority of patients lack such a donor. We sought to develop a novel nonmyeloablative HLA-haploidentical PBSCT approach that could safely be used for patients with severe organ damage. Based on findings in our preclinical model, we developed a phase 1/2 trial using alemtuzumab, 400 cGy total body irradiation, and escalating doses of posttransplant cyclophosphamide (PT-Cy): 0 mg/kg in cohort 1, 50 mg/kg in cohort 2, and 100 mg/kg in cohort 3. A total of 21 patients with SCD and 2 with β-thalassemia received a transplant. The mean hematopoietic cell transplant-specific comorbidity index of 6 reflected patients with cirrhosis, heart failure, and end-stage renal disease. The engraftment rate improved from 1 (33%) of 3 in cohort 1 to 5 (63%) of 8 in cohort 2 and 10 (83%) of 12 in cohort 3. Percentage of donor myeloid and CD3 chimerism also improved with subsequent cohorts. There was no transplant-related mortality, and overall survival was 87%. At present, 0% in cohort 1, 25% in cohort 2, and 50% in cohort 3 remain free of their disease. There was no grade 2 to 4 acute or extensive chronic graft-versus-host disease (GVHD). Therefore, PT-Cy improves engraftment and successfully prevents severe GVHD after nonmyeloablative conditioning in patients with SCD who are at high risk for early mortality. Additional strategies are necessary to decrease the graft rejection rate and achieve a widely available cure for all patients with SCD. This trial was registered at www.clinicaltrials.gov as #NCT00977691.

Alternative Donor/Unrelated Donor Transplants for the β-Thalassemia and Sickle Cell Disease

Considerable progress with respect to donor source has been achieved in allogeneic stem cell transplant for patients with hemoglobin disorders, with matched sibling donors in the 1980s, matched unrelated donors and cord blood sources in the 1990s, and haploidentical donors in the 2000s. Many studies have solidified hematopoietic progenitors from matched sibling marrow, cord blood, or mobilized peripheral blood as the best source-with the lowest graft rejection and graft versus host disease (GvHD), and highest disease-free survival rates. For patients without HLA-matched sibling donors, but who are otherwise eligible for transplant, fully allelic matched unrelated donor (8/8 HLA-A, B, C, DRB1) appears to be the next best option, though an ongoing study in patients with sickle cell disease will provide data that are currently lacking. There are high GvHD rates and low engraftment rates in some of the unrelated cord transplant studies. Haploidentical donors have emerged in the last decade to have less GvHD; however, improvements are needed to increase the engraftment rate. Thus the decision to use unrelated cord blood units or haploidentical donors may depend on the institutional expertise; there is no clear preferred choice over the other. Active research is ongoing in expanding cord blood progenitor cells to overcome the limitation of cell dose, including the options of small molecule inhibitor compounds added to ex vivo culture or co-culture with supportive cell lines. There are inconsistent data from using 7/8 or lower matched unrelated donors. Before routine use of these less matched donor sources, work is needed to improve patient selection, conditioning regimen, GvHD prophylaxis, and/or other strategies.

Hematopoietic stem cell transplantation for people with ß-thalassaemia major

BACKGROUND

Thalassemia is an inherited autosomal recessive blood disorder, caused by mutations in globin genes or their regulatory regions. This results in a reduced rate of synthesis of one of the globin chains that make up haemoglobin. In ß-thalassaemia major there is an underproduction of ß-globin chains combined with excess of free α-globin chains. The excess free α-globin chains precipitate in red blood cells, leading to their destruction (haemolysis) and ineffective erythropoiesis. The conventional approach to treatment is based on the correction of haemoglobin status through regular blood transfusions and iron chelation therapy for iron overload. Although conventional treatment has the capacity to improve the quality of life of people with ß-thalassaemia major, allogeneic hematopoietic stem cell transplantation is the only currently available procedure which has the curative potential. This is an update of a previously published Cochrane Review.

OBJECTIVES

To evaluate the effectiveness and safety of different types of allogeneic hematopoietic stem cell transplantation, in people with severe transfusion-dependant ß-thalassaemia major, ß-thalassaemia intermedia or ß0/+- thalassaemia variants requiring chronic blood transfusion.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search: 18 August 2016.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials comparing allogeneic hematopoietic stem cell transplantation with each other or with standard therapy (regular transfusion and chelation regimen).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies and had planned to extract data and assess risk of bias using standard Cochrane methodologies but no studies were identified for inclusion.

MAIN RESULTS

No relevant studies were retrieved after a comprehensive search of the literature.

AUTHORS' CONCLUSIONS

We were unable to identify any randomised controlled trials or quasi-randomised controlled trials on the effectiveness and safety of different types of allogeneic stem cell transplantation in people with severe transfusion-dependant ß-thalassaemia major or ß0/+- thalassaemia variants requiring chronic blood transfusion. The absence of high-level evidence for the effectiveness of these interventions emphasises the need for well-designed, adequately-powered, randomised controlled clinical trials.

What Unrelated Hematopoietic Stem Cell Transplantation in Thalassemia Taught us about Transplant Immunogenetics

Although the past few decades have shown an improvement in the survival and complication-free survival rates in patients with beta-thalassemia major and gene therapy is already at an advanced stage of experimentation, hematopoietic stem cell transplantation (HSCT) continues to be the only effective and realistic approach to the cure of this chronic non-malignant disease. Historically, human leukocyte antigen (HLA)-matched siblings have been the preferred source of donor cells owing to superior outcomes compared with HSCT from other sources. Nowadays, the availability of an international network of voluntary stem cell donor registries and cord blood banks has significantly increased the odds of finding a suitable HLA matched donor. Stringent immunogenetic criteria for donor selection have made it possible to achieve overall survival (OS) and thalassemia-free survival (TFS) rates comparable to those of sibling transplants. However, acute and chronic graft-versus-host disease (GVHD) remains the most important complication in unrelated HSCT in thalassemia, leading to significant rates of morbidity and mortality for a chronic non-malignant disease. A careful immunogenetic assessment of donors and recipients makes it possible to individualize appropriate strategies for its prevention and management. This review provides an overview of recent insights about immunogenetic factors involved in GVHD, which seem to have a potential role in the outcome of transplantation for thalassemia.

Optimal Outcomes in Young Class 3 Patients With Thalassemia Undergoing HLA-Identical Sibling Bone Marrow Transplantation

BACKGROUND

Bone marrow transplantation (BMT) for class 3 patients with thalassemia is challenging due to high rates of graft rejection and transplant-related mortality. Since the first studies of BMT in the late 1980s, a number of conditioning regimens have been designed to improve outcomes, but with suboptimal results. Here we report the outcome of transplantation in class 3 patients using a modified protocol.

METHODS

Sixty-three patients between 5 and 16.7 years of age with class 3 thalassemia received HLA-matched sibling BMT following either the original protocol (26 patients) or the modified protocol (37 patients). Both regimens comprised preconditioning cytoreduction with hydroxyurea and azathioprine starting at -45 days pretransplant, and fludarabine from days -16 to -12. Conditioning was performed with busulfan and cyclophosphamide (original protocol) or with busulfan, thiotepa, and cyclophosphamide (modified protocol).

RESULTS

The 2 groups showed similar patient demographics. At day 0, the degree of cytoreduction (lymphopenia, neuthropenia, and thrombocytopenia) achieved by the modified protocol was greater than the original protocol. The incidence of graft failure/rejection was significantly higher in the original group (15%; 95% confidence interval [95% CI], 5-32%) compared with the modified group (0%) (P = 0.014). The respective 5-year thalassemia-free survival rates were 73% (95% CI, 51-86%) and 92% (95% CI, 77-97%) (P = 0.047). Both groups showed similar incidences of grades II to IV acute graft-versus host disease. Modified protocol did not increase nonhematological toxicity or infectious complications.

CONCLUSIONS

The modified treatment protocol effectively and safely prevented graft failure/rejection and significantly increased thalassemia-free survival of class 3 patients with thalassemia.

Allogeneic Stem Cell Transplantation in Congenital Hemoglobinopathies Using a Tailored Busulfan-Based Conditioning Regimen: Single-Center Experience

Hematopoietic stem cell transplantation (HSCT) is the only proven curative option for patients with hemoglobinopathies, both thalassemia and sickle cell anemia (SCA). A busulfan-based myeloablative conditioning regimen is the standard of care for HSCT in these patients, although increased treatment-related morbidity, including veno-occlusive disease (VOD), has been demonstrated. Thirty-eight pediatric patients, median age 8 years (range, 6 months to 22 years), suffering from hemoglobinopathy were treated at Rambam Medical Center in Haifa, Israel, between 1998 and 2011. Thirty-four patients had thalassemia major and 4 had SCA. The 38 patients underwent 40 HSCTs, 34 of which were first transplants and 6 second transplants. Most transplants (32/40) were from matched sibling donors. Sources of stem cells were peripheral blood in 30 transplants, bone marrow in 7 transplants, and cord blood in 3 transplants. All received different customized busulfan-based conditioning regimens tailored by pharmacokinetic analysis of busulfan levels. Primary engraftment occurred in 37 of 40 transplants. Neutrophil engraftment (>.5 × 10(9)/L) occurred at a median of 15.3 days post-transplantation (range, 10 to 45). Platelet transfusion independence (>20 × 10(9)/L) occurred at a median of 22.3 days (range, 11 to 60). The rate of 5-year overall survival for thalassemia patients after first transplantation was 90.5% ± 5.3%. The rate of 5-year thalassemia-free survival was 81.7% ± 6.8%. Cumulative incidence of acute graft-versus-host disease (GVHD) was 17.6%. Rate of grades III to IV GVHD was 8.8%. Cumulative incidence of chronic GVHD was 23.5%, with 11.8% incidence of extensive chronic GVHD. One patient developed VOD. Full donor chimerism occurred in 36.4% of patients with class 1 + 2 thalassemia, compared with 78.6% in class 3 thalassemia (P = .049). Overall survival above 90% in patients undergoing their first transplant was demonstrated using busulfan-based conditioning regimens. The low incidence of VOD was probably due to busulfan area under the curve measurements and dose adjustment.

Unrelated donor stem cell transplantation for transfusion-dependent thalassemia

Thalassemia major is characterized by severe anemia dependent on red cell transfusions from infancy. Conservative management requires a safe source of compatible blood throughout life, strategies to combat iron overload, monitoring and treatment of transfusion-related complications, and management of cardiac and/or hepatic dysfunction from iron accumulation. Complications can result in premature morbidity and mortality. Stem cell transplantation is curative, but outcomes depend on the availability of a histocompatible donor, recipient age, and disease-related complications. Successful transplantation requires stable donor engraftment and donor-derived erythropoiesis and a low incidence of graft-versus-host disease, organ toxicities, and mortality. This translates to a cure with good quality of life and life span. Since recipients are at a high risk for graft rejection (prior transfusions, immunocompetency), myeloablative transplants have been the norm. Recent modifications to standard preparative regimens have significantly reduced transplant toxicities, resulting in >80% disease-free survival in children. Aiming to further reduce regimen-related toxicities, such as veno-occlusive liver disease and sterility, a recent trial explored reduced-intensity conditioning in unrelated donor (URD) transplants utilizing marrow or umbilical cord blood in patients without suitable familial donors. This report summarizes advances in URD transplantation for thalassemia, focusing on conditioning regimen nuances.

Pulmonary hypertension associated with thalassemia syndromes

Chronic hemolytic anemia has increasingly been identified as an important risk factor for the development of pulmonary hypertension (PH). Within the thalassemia syndromes, there are multiple mechanisms, both distinct and overlapping, by which PH develops and that differ among β-thalassemia major or intermedia patients. PH in β-thalassemia major correlates with the severity of hemolysis, yet in patients whose disease is well treated with chronic transfusion therapy, the development of PH can be related to cardiac dysfunction and the subsequent toxic effects of iron overload rather than hemolysis. β-Thalassemia intermedia, on the other hand, has a higher incidence of PH owing to the low level of hemolysis that exists over years without the requirement for frequent transfusions, while splenectomy is shown to play an important role in both types. Standard therapies such as chronic transfusion have been shown to mitigate PH, and appropriate chelation therapy can avoid the toxic effects of iron overload, yet is not indicated in many patients. Limited evidence exists for the use of pulmonary vasodilators or other therapies, such as l-carnitine, to treat PH associated with thalassemia. Here, we review the most recent findings regarding the pathogenic mechanisms, epidemiology, presentation, diagnosis, and treatment of PH in thalassemia syndromes.

Correction of murine hemoglobinopathies by prenatal tolerance induction and postnatal nonmyeloablative allogeneic BM transplants

Sickle cell disease (SCD) and thalassemias (Thal) are common congenital disorders, which can be diagnosed early in gestation and result in significant morbidity and mortality. Hematopoietic stem cell transplantation, the only curative therapy for SCD and Thal, is limited by the absence of matched donors and treatment-related toxicities. In utero hematopoietic stem cell transplantation (IUHCT) is a novel nonmyeloablative transplant approach that takes advantage of the immunologic immaturity and normal developmental properties of the fetus to achieve mixed allogeneic chimerism and donor-specific tolerance (DST). We hypothesized that a combined strategy of IUHCT to induce DST, followed by postnatal nonmyeloablative same donor "booster" bone marrow (BM) transplants in murine models of SCD and Thal would result in high levels of allogeneic engraftment and donor hemoglobin (Hb) expression with subsequent phenotypic correction of SCD and Thal. Our results show that: (1) IUHCT is associated with DST and low levels of allogeneic engraftment in the murine SCD and Thal models; (2) low-level chimerism following IUHCT can be enhanced to high-level chimerism and near complete Hb replacement with normal donor Hb with this postnatal "boosting" strategy; and (3) high-level chimerism following IUHCT and postnatal "boosting" results in phenotypic correction in the murine Thal and SCD models. This study supports the potential of IUHCT, combined with a postnatal nonmyelablative "boosting" strategy, to cure Thal and SCD without the toxic conditioning currently required for postnatal transplant regimens while expanding the eligible transplant patient population due to the lack of a restricted donor pool.

Guidelines for the Standard Monitoring of Patients With Thalassemia: Report of the Thalassemia Longitudinal Cohort

Chronic transfusion therapy has played a central role in extending life expectancy for patients with hemoglobinopathies such as thalassemia. However, this life-saving therapy is associated with numerous complications that now comprise the bulk of management considerations for patients with thalassemia. This review reports on the experience of the Thalassemia Longitudinal Cohort and reviews available literature to establish guidelines for the management of patients with thalassemia.

Infectious complications following allogeneic stem cell transplantation by using anti-thymocyte globulin-based myeloablative conditioning regimens in children with hemoglobinopathies

BACKGROUND

Anti-thymocyte globulin (ATG) has been used to prevent graft failure/rejection in the setting of allogeneic stem cell transplantation (allo-SCT) for hemoglobinopathies; however, epidemiology data for transplant-related infections in this population are scarce.

METHOD

We retrospectively analyzed the epidemiology of bacterial, fungal, viral, and parasitic infections in a cohort of 105 children and adolescents with β-thalassemia (n = 100) or sickle cell disease (n = 5) who underwent allo-SCT using human leukocyte antigen (HLA)-identical sibling (n = 96) or HLA-compatible unrelated donors (n = 9) in a single institution. All patients received an ATG-based conditioning regimen.

RESULTS

The cumulative incidence of cytomegalovirus (CMV) viremia was 45.7% (95% confidence interval [CI] 33-55%), developing at a median of 48 (range 12-142) days without evidence of overt CMV disease. Herpes zoster developed in 8 patients at a median of 12 months post transplant, while 10 patients presented with late onset hemorrhagic cystitis at a median of 35 days post transplant. The cumulative incidence of bacteremia was 17.1% (95% CI 10.6-25%), occurring at a median of 74 (range 24-110) days. No patient developed probable or definite invasive fungal infection. Four deaths were recorded; 2 of them were attributed to infections (toxoplasmosis and Pneumocystis jirovecii pneumonia, respectively).

CONCLUSION

The rate of infections after allo-SCT, using an ATG-containing preparative regimen, in our population of pediatric patients with hemoglobinopathies is comparable to that reported elsewhere with the use of non-ATG containing regimens.

Alternative donor transplant of benign primary hematologic disorders

Hematopoietic SCT is currently the only curative therapy for a range of benign inherited and acquired primary hematologic disorders in children, including BM failure syndromes and hemoglobinopathies. The preferred HLA-matched sibling donor is available for only about 25% of such children. However, there has been substantial progress over the last four decades in the use of alternative donors for those without a matched sibling-including HLA-matched unrelated donors, HLA-haploidentical related donors and unrelated-donor umbilical cord blood-so that it is now possible to find a donor for almost every child requiring an allograft. Below, we summarize the relative merits and limitations of the different alternative donors for benign hematologic conditions, first generally, and then in relation to specific disorders, and suggest recommendations for selecting such an alternative donor.

Advances in unrelated and alternative donor hematopoietic cell transplantation for nonmalignant disorders

PURPOSE OF REVIEW

The role of hematopoietic cell transplantation in non-malignant disorders has increased exponentially with the recognition that multiple diseases can be controlled or cured if engrafted with donor-derived cells. This review provides an overview of advances made in alternative donor transplants for nonmalignant disorders.

RECENT FINDINGS

Stem cell sources, novel transplant methods, and sophisticated supportive care have simultaneously made giant strides toward improving the safety and efficacy of hematopoietic cell transplantation. This has led to the utilization of marrow, cord, peripheral blood stem cell and haploidentical stem cell sources, and novel reduced toxicity or reduced intensity conditioning regimens to transplant non-malignant disorders such as immune dysfunctions, marrow failure syndromes, metabolic disorders and hemoglobinopathies. Transplant complications such as graft rejection, infections, and graft versus host disease are better combated in this modern era of medicine, achieving better survival with decreased late effects. These aspects of transplant for non-malignant disorders are discussed.

SUMMARY

This review presents the progress made in the realm of hematopoietic cell transplantation for non-malignant disorders. It advocates the consideration of alternative donor transplants in the absence of human leukocyte antigen matched siblings when indicated by disease severity. The ultimate goal is to provide curative transplant options for more patients that can benefit from this intervention, prior to detrimental outcomes.

Increasing prevalence of thalassemia in America: Implications for primary care

Thalassemia, once a rarity in the United States, is increasingly encountered in clinical practice due to shifts in immigration. Early carrier screening in at-risk populations can help clinicians implement genetic counseling and prevent new cases. Chronic transfusions are the mainstay of therapy for patients with severe thalassemia (beta thalassemia major), and are used intermittently in individuals with milder forms of thalassemia (Hb H/H Constant Spring disease and beta thalassemia intermedia). Iron overload is a major source of morbidity and mortality in individuals with transfusion and non-transfusion-dependent thalassemia, necessitating iron chelation therapy. Iron overload contributes to increased risk of cirrhosis, heart failure, and endocrinopathies, while ineffective erythropoiesis and hemolysis contribute to multiple complications, including splenomegaly, extramedullary hematopoiesis, pulmonary hypertension, and thrombosis. An understanding of the importance of carrier screening, complications, monitoring, and management strategies, coupled with collaboration with a hematologist with thalassemia expertise, is essential to reduce the morbidity and mortality in patients with thalassemia.

Gene therapy for hemoglobinopathies: the state of the field and the future

After nearly two decades of struggle, gene therapy for hemoglobinopathies using vectors carrying β or γ-globin gene has finally reached the clinical doorsteps. This was made possible by advances made in our understanding of critical regulatory elements required for high level of globin gene expression and improved gene transfer vectors and methodologies. Development of gene editing technologies and reprogramming somatic cells for regenerative medicine holds the promise of genetic correction of hemoglobinopathies in the future. This article will review the state of the field and the upcoming technologies that will allow genetic therapeutic correction of hemoglobinopathies.

Hematopoietic stem cell transplantation for people with ß-thalassaemia major

BACKGROUND

Thalassemia is an inherited blood disorder, caused by mutations in regulatory genes and transmitted as an autosomal recessive disorder, which results in a reduced rate of synthesis of one of the globin chains that make up haemoglobin. In ß-thalassaemia major there is an underproduction of ß-globin chains combined with excess of free α-globin chains. The excess free α-globin chains damage the red blood cell membranes, leading to their destruction and a phenomenon termed ineffective erythropoiesis. The conventional approach to treatment is based on the correction of haemoglobin status through regular blood transfusions and iron chelation therapy for iron overload. Although conventional treatment has the capacity to improve the quality of life of people with ß-thalassaemia major, allogeneic hematopoietic stem cell transplantation is the only currently available procedure which has the potential to definitively cure the disease.

OBJECTIVES

To evaluate the effectiveness and safety of different types of allogeneic hematopoietic stem cell transplantation, in people with severe transfusion-dependant ß-thalassaemia major, ß-thalassaemia intermedia or ß0/+- thalassaemia variants requiring chronic blood transfusion.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of the most recent search: 11 November 2013.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials comparing allogeneic hematopoietic stem cell transplantation with each other or with standard therapy (regular transfusion and chelation regimen).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies and had planned to extract data and assess risk of bias using standard Cochrane Collaboration methodologies but no studies were identified for inclusion.

MAIN RESULTS

No relevant studies were retrieved after a comprehensive search of the literature.

AUTHORS' CONCLUSIONS

We were unable to identify any randomised controlled trials or quasi-randomised controlled trials on the effectiveness and safety of different types of allogeneic stem cell transplantation in people with severe transfusion-dependant ß-thalassaemia major or ß0/+- thalassaemia variants requiring chronic blood transfusion. The absence of high-level evidence for the effectiveness of these interventions emphasises the need for well-designed, adequately-powered, randomised controlled clinical trials.

Hematopoietic stem cell transplantation for patients with sickle cell disease: progress and future directions

Research has solidified matched sibling marrow, cord blood, or mobilized peripheral blood as the best source for allogeneic hematopoietic stem cell transplantation for patients with sickle cell disease, with low graft rejection and graft-versus-host disease (GVHD) and high disease-free survival rates. Fully allelic matched unrelated donor is an option for transplant-eligible patients without HLA-matched sibling donors. Unrelated cord transplant studies reported high GVHD and low engraftment rates. Haploidentical transplants have less GVHD, but improvements are needed to increase the low engraftment rate. The decision to use unrelated cord blood units or haploidentical donors depends on institutional expertise.

Development and Recent Progresses of Gene Therapy for β-Thalassemia

β-thalassemias are among the most common inherited monogenic disorders worldwide due to mutations in the β-globin gene that reduce or abolish the production of the β-globin chain resulting in transfusion-dependent chronic anemia. Currently, the only curative treatment is allogeneic hematopoietic stem cells (HSCs) transplantation, but this option is limited by the a vailability of HLA-matched donor. Gene therapy, based on autologous transplantation of genetically corrected HSCs, holds the promise to treat patients lacking a compati ble bone marrow donor. I nit ial attempts of gene transfer have been unsuccessful due to limitations of available vectors to stably transfer a globin gene in HSCs and reach high and regulated expression in the erythroid progeny. With the advent of lentiviral vectors (LVs), based on human immunodeficiency virus, many of the initial limitations have been overcome. Since 2000 when Sadelain and co-workers first demonstrated successful globin gene transfer in murine thalassemia models with improvement of the phenotype using a recombinant β globin/LV, several other groups have developed different vectors encoding either β, γ or mutated globin genes and confirmed these results in both murine models and erythroid progeny derived from patient’s HSCs. In light of these encouraging results, research has recently moved into clinical trials that are ongoing or soon to begin. One participant in an ongoing gene transfer trial for β-thalassemia has achieved clinical benefit with elimination of his transfusi on re quirement. Here , dev elopmen t and recent progress of gene therapy for β-thalassemia is reviewed.

Successful unrelated umbilical cord blood transplantation for class 3 β-thalassemia major using a reduced-toxicity regimen

Unrelated umbilical CB transplant for class 3 β-thalassemia major is associated with an increased risk of mortality and non-engraftment. We describe two patients who underwent successful unrelated umbilical CB transplant using a novel reduced-toxicity preparative regimen. This regimen may be sufficiently immunosuppressive and myeloablative to ensure engraftment with reduced risks of toxicity and mortality. Close monitoring of HHV-6 viral load is advised for patients undergoing transplant with this regimen.