Unrelated cord blood transplantation for thalassaemia: a single-institution experience of 35 patients

High-dose individualized antithymocyte globulin with therapeutic drug monitoring in high-risk cord blood transplant

BACKGROUND

Graft-versus-host disease (GvHD) and rejection are main limitations of cord blood transplantation (CBT), more so in patients with severe inflammation or previous rejections. While rigorous T-cell depletion with antithymocyte globulin (ATG) is needed to prevent GvHD and rejection, overexposure to ATG leads to slow T-cell recovery after transplantation, especially in CBT.

OBJECTIVE

To evaluate high-dose, upfront ATG with individualized dosing and therapeutic drug monitoring (TDM) in pediatric CBT for patients at high risk for GvHD and rejection.

STUDY DESIGN

Heavily inflamed patients and patients with a recent history of rejection were eligible for individualized high-dose ATG with real-time TDM. The ATG dosing scheme was adjusted to target a post-CBT exposure of <10 AU*day/mL, while achieving a pre-CBT exposure of 60-120 AU*day/mL; exposure levels previously defined for optimal efficacy and safety in terms of reduced GvHD and rejection, respectively. Main outcomes of interest included efficacy (target exposure attainment) and safety (incidence of GvHD and rejection). Other outcomes of interest included T-cell recovery and survival.

RESULTS

Twenty-one patients were included ranging from 2 months to 18 years old, receiving an actual median cumulative dose of ATG of 13.3 mg/kg (range 6-30 mg/kg) starting at a median 15 days (range 12-17) prior to CBT. Dosing was adjusted in 14 patients (increased in 3 and decreased in 11 patients). Eighteen (86%) and 19 (91%) patients reached the target pre-CBT and post-CBT exposure, respectively. Cumulative incidence for acute GvHD was 34% (95% CI 23-45) and 5% (95% CI 0-10%) for grade 2-4 and grade 3-4, respectively; cumulative incidence of rejection was 9% (95% CI 2-16%). Overall survival was 75% (95% CI 65-85%).

CONCLUSION

Individualized high-dose ATG with TDM is feasible and safe for patients with hyperinflammation in a CBT setting. We observe high target ATG exposure attainment, good immune reconstitution (despite very high doses of ATG) and acceptable rates of GvHD and rejection.

Hematopoietic Stem Cell Transplantation in Thalassemia

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only consolidated, potentially curative treatment for patients with transfusion-dependent thalassemia major. In the past few decades, several new approaches have reduced the toxicity of conditioning regimens and decreased the incidence of graft-versus-host disease, improving patients' outcomes and quality of life. In addition, the progressive availability of alternative stem cell sources from unrelated or haploidentical donors or umbilical cord blood has made HSCT a feasible option for an increasing number of subjects lacking an human leukocyte antigen (HLA)-identical sibling. This review provides an overview of allogeneic hematopoietic stem cell transplantation in thalassemia, reassesses current clinical results, and discusses future perspectives.

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.

Curative therapy for hemoglobinopathies: an International Society for Cell & Gene Therapy Stem Cell Engineering Committee review comparing outcomes, accessibility and cost of ex vivo stem cell gene therapy versus allogeneic hematopoietic stem cell transplantation

Thalassemia and sickle cell disease (SCD) are the most common monogenic diseases in the world and represent a growing global health burden. Management is limited by a paucity of disease-modifying therapies; however, allogeneic hematopoietic stem cell transplantation (HSCT) and autologous HSCT after genetic modification offer patients a curative option. Allogeneic HSCT is limited by donor selection, morbidity and mortality from transplant conditioning, graft-versus-host disease and graft rejection, whereas significant concerns regarding long-term safety, efficacy and cost limit the broad applicability of gene therapy. Here the authors review current outcomes in allogeneic and autologous HSCT for transfusion-dependent thalassemia and SCD and provide our perspective on issues surrounding accessibility and costs as barriers to offering curative therapy to patients with hereditary hemoglobinopathies.

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.

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 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.

Epidemiology and treatment of beta thalassemia major in China

Thalassemia, classified as the main types α- and β-thalassemia, is a single gene disorder resulting from globin chain synthesis impairment through the mutation or deletion of globin genes. The incidence of thalassemia is high worldwide, with high associated mortality. Therefore, treatment is important to improve patient outcomes. This paper reviews the current status of β-thalassemia major in China, including its epidemiology and treatment.

Hematopoietic Stem Cell Transplantation for Severe Thalassemia Patients from Haploidentical Donors Using a Novel Conditioning Regimen

Patients with severe thalassemia commonly have a survival that is significantly shorter than that of the general population. Allogeneic hematopoietic stem cell transplantation (allo-SCT) is the only established treatment that is potentially curative, but it is limited by the availability of donors and the medical condition of the patient. To expand the donor pool to include haploidentical related donors, we introduced a program consisting of a pharmacologic pretransplant immune suppression phase (PTIS) and 2 courses of dexamethasone and fludarabine, followed by pretransplant conditioning with fludarabine-i.v. busulfan and post-transplant graft-versus-host disease (GVHD) prophylaxis with cyclophosphamide, tacrolimus, and mycophenolate mofetil. We transplanted 83 consecutive transfusion-dependent patients with thalassemia (median age, 12 years; range, 1 to 28 years) with a minimum follow-up of 6 months (median, 15 months; range, 7 to 53 months); the 3-year projected overall and event-free survival is over 96%, and there have been no secondary graft failures. Of the first 31 patients, we had 2 graft failures, both of them occurring in patients with extremely high titers of anti-donor-specific HLA antibodies (anti-DSAs), but after adjusting the PTIS to include bortezomib and rituximab for patients with high titers of anti-DSAs and using pharmacologic dose guidance for busulfan, we had no graft failures in the last 52 patients. Six (7%) of 83 patients developed severe GVHD. We conclude that this is a safe and efficacious approach to allogeneic SCT in thalassemia, yielding results comparable to those available for patients with fully matched donors.

Current status of umbilical cord blood transplantation in children

The first umbilical cord blood (UCB) transplantation was performed 30 years ago. UCB transplantation (UCBT) is now widely used in children with malignant and non-malignant disorders who lack a matched family donor. UCBT affords a lower incidence of graft-versus-host disease compared to alternative stem cell sources, but also presents a slower immune recovery and a high risk of infections if serotherapy is not omitted or targeted within the conditioning regimen. The selection of UCB units with high cell content and good human leucocyte antigen match is essential to improve the outcome. Techniques, such as double UCBT, ex vivo stem cell expansion and intra-bone injection of UCB, have improved cord blood engraftment, but clinical benefit remains to be demonstrated. Cell therapies derived from UCB are under evaluation as potential novel strategies to reduce relapse and viral infections following transplantation. In recent years, improvements within haploidentical transplantation have reduced the overall use of UCBT as an alternative stem cell source; however, each may have its relative merits and disadvantages and tailored use of these alternative stem cell sources may be the optimal approach.

Hematopoietic Stem Cell Transplantation in Thalassemia

Although recent advances in gene therapy are expected to increase the chance of disease cure in thalassemia major, at present hematopoietic stem cell transplantation (HSCT) remains the only consolidated curative approach for this disorder. The widest experience has been obtained in the HLA-matched family donor (MFD) setting, with probabilities of overall and thalassemia-free survival exceeding 90% and 85%, respectively. As for most patients a suitable MFD is not available, alternative donors (HLA-matched unrelated donor, unrelated cord blood, HLA-haploidentical relative) have been increasingly explored, translating into the expansion of the number of patients treatable with HSCT.

Single nucleotide polymorphisms within HLA region are associated with disease relapse for patients with unrelated cord blood transplantation

Disease relapse occurs in unrelated cord blood transplantation (CBT) even when the alleles of human leukocyte antigen (HLA) are fully matched between donor and recipient. This is similar to that observed in other types of hematopoietic stem cell transplantation. Fourteen single nucleotide polymorphisms (SNPs) within the HLA region have been reported previously by Petersdorf et al. and Piras et al. as transplantation determinants in unrelated hematopoietic cell transplantation. In this study, the genomic sequences within 500 base pairs upstream and downstream of the fourteen transplantation-related SNPs from 53 patients and their HLA-matched unrelated donors were analyzed for determining whether or not genetic variants, conferred by either recipient or donor SNP genotype or by recipient-donor SNP mismatching, were associated with the risk of relapse. Seven SNPs were associated with the risk of relapse in unrelated CBT. These included the donor genotype with the SNPs of rs2523675 and rs2518028 at the telomeric end of HCP5 gene, rs2071479 in the intron of the HLA-DOB gene, and rs2523958 in the MICD gene; and the recipient genotype with SNPs of rs9276982 in the HLA-DOA gene, and rs435766 and rs380924 in the MICD gene. As measured by pair-wise linkage disequilibrium (LD) with D′ as the parameter for normalized standard measurement of LD which compares the observed and expected frequencies of one haplotype comprised by alleles at different loci, rs2523675 had high LD with rs4713466 (D′ = 0.86) and rs2523676 (D′ = 0.91) in the HCP5 gene. The rs2518028 had no LD with all other SNPs except rs2523675 (D′ = 0.76). This study provides the basis for developing a method or algorithm for selecting better unrelated CBT candidate donors.

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.

Hematopoietic stem cell transplantation for children with β-thalassemia major: multicenter experience in China

BACKGROUND

β-Thalassemia major (β-TM) has become a public health problem in mainland China. Hematopoietic stem cell transplantation (HSCT) has remained the only cure for β-TM in mainland China since 1998.

METHODS

This multicenter retrospective study provides a comprehensive review of the outcomes of 50 pediatric patients with β-TM who received HSCT between 1998 and 2009 at five centers in mainland China. Both related (n = 35) and unrelated donors (n = 15) with complete human leukocyte antigen matches were included. The stem cell sources included bone marrow (BM), peripheral blood stem cells, umbilical cord blood (UCB) and a combination of BM and UCB or a combination of BM and peripheral blood stem cells from a single sibling donor.

RESULTS

The probabilities of 5-year overall survival (OS) and thalassemia-free survival (TFS) after the first HSCT were 83.1 and 67.3%, respectively. Graft failure (GF) occurred in 17 patients. Univariate analyses showed that umbilical cord blood transplantation (UCBT) was one of the potential risk factors for decreased OS (P = 0.051), and that UCBT (P = 0.002) was potentially related to TFS. GF incidence was distinct between the UCBT and non-UCBT groups (P = 0.004). Four cases of UCB-BM combined transplantation led to decreased risks of mortality and recurrence. In the UCBT group, related donor transplantation produced more favorable results than unrelated donor transplantation in OS (P = 0.009) but not in TFS (P = 0.217).

CONCLUSIONS

GF was the primary cause of UCBT failure. Though UCBT from related donors was not favorable, the combined transplantation of UCB and BM could improve the prognosis of UCBT.

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.

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.

Survival and complication rates in patients with thalassemia major in Taiwan

BACKGROUND

While transfusion and iron chelation therapy for thalassemia major (TM) has improved dramatically in recent years, the consequences of this improvement (current rates of survival and TM-related complications) remain unknown.

METHODS

This nationwide population-based cohort study analyzed 2007-2011 data obtained from the Taiwanese National Health Insurance Research Database.

RESULTS

After excluding those patients receiving hematopoietic stem cell transplantation, we enrolled 454 patients with TM who received transfusion and chelation therapy (median age, 17.2 years). Among these patients, the mortality rate was 2.9% in 2007, 2.3% in 2008, 2.9% in 2009, 2.6% in 2010, and 0.7% in 2011. Heart was the most common target organ of TM-related complications. There were 80 patients (17.6%) with arrhythmia and 86 patients (18.9%) with congestive heart failure. Dysfunction of endocrine organs was common, and the most common endocrinopathy was hypogonadism (23.1%), followed by diabetes (21.2%). There were 75 patients (16.5%) with liver cirrhosis and 79 patients (17.4%) with osteoporosis.

CONCLUSIONS

Adequate red blood cell transfusion and iron chelation is available to all patients with TM in Taiwan under the universal health insurance system, and has resulted in reduction of TM-related mortality to very low levels. As these patients get older, early detection of complications and adequate intervention are important to quality-of-life improvement.

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.

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.

Monitoring of Microscopic Filamentous Fungi in Indoor Air of Transplant Unit

AIM

The aim of the study was to control the microbial contamination of indoor air monitored monthly at the Transplant Unit of the University Hospital Olomouc from August 2010 to July 2011.

METHODS

The unit is equipped with a three-stage air filtration system with HEPA filters. The MAS-100 air sampler (Merck, GER) was used. Twenty locations were singled out for the purposes of collecting a total of 720 samplings of the indoor air. Swabs of the HVAC diffusers at the sampling locations were always carried out after the sampling of the indoor air.

RESULTS

In total, 480 samples of the indoor air were taken for Sabouraud chloramphenicol agar. In 11 cases (2.29%) the cultivation verified the presence of microscopic filamentous fungi. Only two cases involved the sanitary facilities of a patient isolation box; the other positive findings were from the facilities. The most frequent established genus was Aspergillus spp. (4x), followed by Trichoderma spp. (2x) and Penicillium spp. (2x), Paecilomyces spp., Eurotium spp., and Chrysonilia spp. (1x each). In 2 cases the cultivation established sterile aerial mycelium, unfortunately no further identification was possible. A total of 726 swabs of HVAC diffusers were collected (2 positive-0.28%). The study results demonstrated the efficacy of the HVAC equipment.

CONCLUSIONS

With the continuing increase in the number of severely immunocompromised patients, hospitals are faced with the growing problem of invasive aspergillosis and other opportunistic infections. Preventive monitoring of microbial air contaminants is of major importance for the control of invasive aspergillosis.

Current and future alternative therapies for beta-thalassemia major

Beta-thalassemia is a group of frequent genetic disorders resulting in the synthesis of little or no β-globin chains. Novel approaches are being developed to correct the resulting α/β-globin chain imbalance, in an effort to move beyond the palliative management of this disease and the complications of its treatment (e.g. life-long red blood cell transfusion, iron chelation, splenectomy), which impose high costs on healthcare systems. Three approaches are envisaged: fetal globin gene reactivation by pharmacological compounds injected into patients throughout their lives, allogeneic hematopoietic stem cell transplantation (HSCT), and gene therapy. HSCT is currently the only treatment shown to provide an effective, definitive cure for β-thalassemia. However, this procedure remains risky and histocompatible donors are identified for only a small fraction of patients. New pharmacological compounds are being tested, but none has yet made it into common clinical practice for the treatment of beta-thalassemia major. Gene therapy is in the experimental phase. It is emerging as a powerful approach without the immunological complications of HSCT, but with other possible drawbacks. Rapid progress is being made in this field, and long-term efficacy and safety studies are underway.

Alternative donor allogeneic hematopoietic cell transplantation for hemoglobinopathies

Allogeneic hematopoietic stem cell transplantation (HSCT) offers a curative therapy for patients with hemoglobinopathies, mainly severe sickle cell disease (SCD) and thalassemia (TM). However, the applicability of HSCT has been limited mainly by donor availability, with a less than 25%-30% of eligible patients having human leukocyte antigen (HLA)-matched sibling donors. Previous outcomes using alternate donor options have been markedly inferior due to increased regimen-related toxicity, transplant-related mortality, graft failure, and graft-versus-host disease (GVHD). Advances in transplant technology, including high-resolution HLA typing, improved GVHD prophylactic approaches with tolerance induction, and better supportive care over the last decade, are addressing these historical challenges, resulting in increasing donor options. Herein, we review alternate donor HSCT approaches for severe SCD and TM using unrelated donors, umbilical cord blood units, or related haploidentical donors. Though this is an emerging field, early results are promising and in selected patients, this may be the preferred option to mitigate against the age-related morbidity and early mortality associated with these disorders.

Successful matched sibling donor marrow transplantation following reduced intensity conditioning in children with hemoglobinopathies

Fifty-two children with symptomatic sickle cell disease sickle cell disease (SCD) (N = 43) or transfusion-dependent thalassemia (N = 9) received matched sibling donor marrow (46), marrow and cord product (5), or cord blood (1) allografts following reduced intensity conditioning (RIC) with alemtuzumab, fludarabine, and melphalan between March 2003 and May 2014*. The Kaplan-Meier probabilities of overall and event-free survival at a median of 3.42 (range, 0.75-11.83) years were 94.2% and 92.3% for the group, 93% and 90.7% for SCD, and 100% and 100% for thalassemia, respectively. Treatment-related mortality (all related to graft versus host disease, GVHD) was noted in three (5.7%) recipients, all 17-18 years of age. Acute and chronic GVHD was noted in 23% and 13%, respectively, with 81% of recipients off immunosuppression by 1 year. Graft rejection was limited to the single umbilical cord blood recipient who had prompt autologous hematopoietic recovery. Fourteen (27%) had mixed chimerism at 1 year and beyond; all had discontinued immunosuppression between 4 and 12 months from transplant with no subsequent consequence on GVHD or rejection. Infectious complications included predominantly bacteremia (48% were staphylococcus) and CMV reactivation (43%) necessitating preemptive therapy. Lymphocyte recovery beyond 6 months was associated with subsidence of infectious complications. All patients who engrafted were transfusion independent; no strokes or pulmonary complications of SCD were noted, and pain symptoms subsided within 6 months posttransplant. These findings support using RIC for patients with hemoglobinopathy undergoing matched sibling marrow transplantation (*www.Clinical Trials.gov: NCT00920972, NCT01050855, NCT02435901).

A complicated disease: what can be done to manage thalassemia major more effectively?

Patients with thalassemia major suffer from many complications, but in the last two decades their lives have improved both in length and quality. We report herein the most common complications and the recent advances that have changed the course of this disease. Also, we report in detail some of the new therapeutic strategies already introduced in practice and briefly some that are still being developed.

Hematopoietic stem cell transplantation in thalassemia major and sickle cell disease: indications and management recommendations from an international expert panel

Thalassemia major and sickle cell disease are the two most widely disseminated hereditary hemoglobinopathies in the world. The outlook for affected individuals has improved in recent years due to advances in medical management in the prevention and treatment of complications. However, hematopoietic stem cell transplantation is still the only available curative option. The use of hematopoietic stem cell transplantation has been increasing, and outcomes today have substantially improved compared with the past three decades. Current experience world-wide is that more than 90% of patients now survive hematopoietic stem cell transplantation and disease-free survival is around 80%. However, only a few controlled trials have been reported, and decisions on patient selection for hematopoietic stem cell transplantation and transplant management remain principally dependent on data from retrospective analyses and on the clinical experience of the transplant centers. This consensus document from the European Blood and Marrow Transplantation Inborn Error Working Party and the Paediatric Diseases Working Party aims to report new data and provide consensus-based recommendations on indications for hematopoietic stem cell transplantation and transplant management.

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.

Umbilical cord blood: a trustworthy source of multipotent stem cells for regenerative medicine

It is conservatively estimated that one in three individuals in the US might benefit from regenerative medicine therapy. However, the relation of embryonic stem cells (ESCs) to human blastocysts always stirs ethical, political, moral, and emotional debate over their use in research. Thus, for the reasonably foreseeable future, the march of regenerative medicine to the clinic will depend upon the development of non-ESC therapies. Current sources of non-ESCs easily available in large numbers can be found in the bone marrow, adipose tissue, and umbilical cord blood (UCB). UCB provides an immune-compatible source of stem cells for regenerative medicine. Owing to inconsistent results, it is certainly an important and clinically relevant question whether UCB will prove to be therapeutically effective. This review will show that UCB contains multiple populations of multipotent stem cells, capable of giving rise to hematopoietic, epithelial, endothelial, and neural tissues both in vitro and in vivo. Here we raise the possibility that due to unique immunological properties of both the stem cell and non-stem cell components of cord blood, it may be possible to utilize allogeneic cells for regenerative applications without needing to influence or compromise the recipient immune system.

Plasma-depleted versus red cell-reduced umbilical cord blood

Umbilical cord blood banks use two methods to store frozen umbilical cord blood (UCB): red cell reduction (RCR) or plasma depletion (PD). The RCR method centrifuges cord blood in hetastarch or albumin to isolate 21 ml of cord blood containing mostly white blood cells, adds 4 ml of 50% dimethyl sulfoxide (DMSO), and then freezes the resulting 25 ml of cell suspension. The PD method removes plasma, saves all the cells, and freezes the cells in 10% DMSO. PD UCB units are cheaper to process but more expensive to store and somewhat more troublesome to thaw. However, when properly thawed and washed, PD UCB units have as many or more total nucleated cells (TNCs), CD34(+) cells, and colony-forming units (CFU) than RCR units. Two studies suggest that PD units have 20-25% more TNCs, MNCs, and CD34(+) cells, as well as two to three times more CFU than RCR units. Higher TNC, CD34(+), and CFU counts predict engraftment rate with faster neutrophil and platelet recovery. PD units have high engraftment rates with low mortality and high disease-free survival, comparable with clinical results of treatments with RCR units. One recent series of studies suggests that PD units are more effective for treating thalassemia with 2-year survival rates of 88%, disease-free survival rates of 74%, and 100% cure rate for children under age 7, compared to only 61% overall survival and 23% disease-free survival rate in thalassemic children treated with RCR units. These findings suggest that PD units not only have more TNCs, CD34(+) cells, and CFU than RCR units but also have high engraftment rates and may be more effective for treating certain conditions such as β-thalassemia.

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.

Thalassemia and the hypercoagulable state

Thalassemia, an inherited hemolytic disorder, is associated with a high incidence of thrombosis. The major mechanisms underlying thromboembolism (TE) are an abnormal red blood cell surface, platelet activation and endothelial cell activation. A higher risk of TE is found in splenectomized patients due to thrombocytosis and increased abnormal RBCs in the circulation. Regular RBC transfusions can reduce the proportion of abnormal RBCs and suppress erythropoiesis. Regular transfusion may also reduce levels of circulating coagulation markers and reduce elevated pulmonary artery pressure. To prevent thromboembolic events, aspirin is now recommended for splenectomized patients with thrombocytosis.

Umbilical cord blood: an evolving stem cell source for sickle cell disease transplants

Allogeneic hematopoietic stem cell transplantation has proven benefit in controlling sickle cell disease-related vasculopathy and organ damage. Myeloablative matched sibling donor cord transplants have excellent outcomes in sickle cell disease. Unrelated donor transplant options are often deferred because of a lack of suitable human leukocyte antigen-matched donors, a problem especially relevant to minority populations. Umbilical cord blood transplantation allows for more mismatching from the graft-versus-host disease perspective and the donor pool is expandable with effort and education. Drawbacks such as increased rates of graft rejection, a fixed cell dose, delayed immune reconstitution, and transplant-related mortality have deterred unrelated cord transplant efforts. However, the transplant community continues to make enormous strides in this transplant realm in areas of immunogenetics, stem cell expansion, conditioning regimens, and supportive care. This has allowed the development of new studies that are currently ongoing, exploring ways to make cord blood transplantation successful and safer. The goal is to make unrelated donor cord blood transplantation for sickle cell disease merit early consideration in patients who stand to benefit from this approach.

Gauchers disease--a reappraisal of hematopoietic stem cell transplantation

Hematopoietic stem cell transplantation (HSCT), first performed in 1984, was the first treatment approach for Gaucher's disease (GD) which had curative intent. The early successes in HSCT were soon eclipsed by the introduction of a highly effective enzyme replacement therapy (ERT), which has remained the single most widely used treatment. Experience with HSCT is limited to about 50 reported cases, mainly performed in the last century, with an overall survival around 85%. HSCT typically achieves complete correction of visceral and bony changes and can fully stabilize neurological features in otherwise progressive type II and III GD. ERT, in contrast, is completely safe and effective, but is limited by cost, incomplete resolution of visceral, hematological, and bony features in some patients, and lack of neurological correction in type II and III disease. In this review, we summarize and compare HSCT and ERT. With 20 years of experience of ERT, its limitations as well as its advantages are now well delineated. Meanwhile progress in HSCT over the last decade suggests that transplantation would today represent a very safe curative approach for GD offering one time complete correction of the disease, contrasting with the lifelong need for ERT with its associated expense and dependence on sophisticated drug manufacture. Additionally, unlike ERT, HSCT can be beneficial for neurological forms of GD. We conclude that the time has come to re-evaluate HSCT in selected patients with GD where ERT is less likely to fully eradicate symptoms of the disease.

Advances in stem cell transplantation and gene therapy in the β-hemoglobinopathies

High-level production of β-globin, γ-globin, or therapeutic mutant globins in the RBC lineage by hematopoietic stem cell gene therapy ameliorates or cures the hemoglobinopathies sickle cell disease and beta thalassemia, which are major causes of morbidity and mortality worldwide. Considerable efforts have been made in the last 2 decades in devising suitable gene-transfer vectors and protocols to achieve this goal. Five years ago, the first βE/β0-thalassemia major (transfusion-dependent) patient was treated by globin lentiviral gene therapy without injection of backup cells. This patient has become completely transfusion independent for the past 4 years and has global amelioration of the thalassemic phenotype. Partial clonal dominance for an intragenic site (HMGA2) of chromosomal integration of the vector was observed in this patient without a loss of hematopoietic homeostasis. Other patients are now receiving transplantations while researchers are carefully weighing the benefit/risk ratio and continuing the development of further modified vectors and protocols to improve outcomes further with respect to safety and efficacy.

HLA-matched family hematopoetic stem cell transplantation in children with beta thalassemia major: the experience of the Turkish Pediatric Bone Marrow Transplantation Group

From January 1991 to June 2009, 245 children with beta thalassemia major who underwent their first allogeneic HSCT in Turkey and who were followed for a minimum of one yr post-transplantation were enrolled this study. The median age of the patients was 6.6 yr old (range, 1-22 yr). The distribution of Pesaro risk class I, II, and III categories was 41, 130, and 63 children, respectively. The median serum ferritin level was 2203 ng/mL. Eighty-eight patients received bone marrow (BM) stem cells; 137, peripheral blood (PB) stem cells; and 20, cord blood (CB) stem cells. The donors were HLA-matched siblings or parents. Median engraftment times were shorter in PBSCT patients compared with the BMT group (p < 0.001). Grade II-IV acute GvHD was observed in 33 children (13.5%), while cGvHD was observed in 28 patients (12.5%), eight of whom had the extensive form. Thalassemic reconstitution was observed in 43 (17%) of the transplant patients. Post-transplant aplasia occurred in three patients, and the TRM rate was 7.75%. Seventeen patients were lost after 100 days. The thalassemia-free survival and OS rates were 68% (95% CI, 61.8-74.2) and 85.0% (95% CI, 80.2-89.8), respectively. We believe that this study is important because it is the first multicenter national data for children with beta thalassemia major receiving HSCT.

A novel conditioning regimen improves outcomes in β-thalassemia major patients using unrelated donor peripheral blood stem cell transplantation

We used a novel NF-08-TM transplant protocol based on intravenous busulfan, cyclophosphamide, fludarabine, and thiotepa in 82 consecutive patients with β-thalassemia major (TM), including 52 with allogeneic peripheral blood stem cell transplantation (PBSCT) from unrelated donors (UDs) with well-matched human leukocyte antigens and 30 with hematopoietic stem cell transplantation (HSCT) from matched sibling donors (MSDs). The median age at transplantation was 6.0 years (range, 0.6-15.0 years), and the ratio of male-to-female patients was 56:26. The median follow-up time was 24 months (range, 12-39 months). The estimated 3-year overall survival and TM-free survival were 92.3% and 90.4% in the UD-PBSCT group and 90.0% and 83.3% in the MSD-HSCT group. The cumulative incidences of graft rejection and grades III-IV acute graft-versus-host disease were 1.9% and 9.6%, respectively, in the UD-PBSCT group and 6.9% and 3.6%, respectively, in the MSD-HSCT group. The cumulative incidence of transplant-related mortality was 7.7% in the UD-PBSCT group and 10.0% in the MSD-HSCT group. In conclusion, UD-PBSCTs using the well-tolerated NF-08-TM protocol show similar results to MSD-HSCTs and can be used to treat β-thalassemia patients in the absence of MSDs.

Cell recovery comparison between plasma depletion/reduction- and red cell reduction-processing of umbilical cord blood

BACKGROUND AIMS

Limited cell dose has hampered the use of cord blood transplantation (CBT) in adults. One method of minimizing nucleated cell loss in cord blood (CB) processing is to deplete or reduce plasma but not red blood cells - plasma depletion/reduction (PDR).

METHODS

The nucleated cell loss of PDR was studied, and determined to be less than 0.1% in the discarded supernatant plasma fraction in validation experiments. After testing and archival sampling, the median nucleated cell recovery for PDR processing was 90%, and median CD34(+) cell recovery 88%. In a CB bank inventory of 12 339 products with both pre- and post-processing total nucleated cells (TNC), PDR processing resulted in median post-processing TNC recoveries of 90.0% after testing and archival samples removal. Using the same 10 CB units divided into two halves, we compared directly the recovery of PDR against hydroxyethyl starch red cell reduction (RCR) for TNC, CD34(+) cells and colony-forming units (CFU-GM, CFU-E, CFU-GEMM and total CFU) after parallel processing. We also compared the loss of very small embryonic-like stem cells (VSEL).

RESULTS

We demonstrated significantly higher recoveries using PDR for TNC (124%), CD34(+) cells (121%), CFU-GM (225%), CFU-GEMM (201%), total CFU (186%) and VSEL (187%). The proportion of high TNC products was compared between 10 912 PDR and 38 819 RCR CB products and found to be 200% higher for products that had TNC ≥150 × 10(7) (P = 0.0001) for the PDR inventory.

CONCLUSIONS

Our data indicate that PDR processing of CB provides a significantly more efficient usage of this valuable and scarce resource.