Umbilical cord blood transplantation for children with thalassemia and sickle cell disease

Durable engraftment after pharmacological pre-transplant immune suppression followed by reduced-toxicity myeloablative haploidentical stem cell transplantation in highly HLA-immunized adults with sickle cell disease

Allogeneic stem cell transplantation (Allo-SCT) is the only rapidly available curative treatment modality in patients with severe sickle cell disease (SCD). The development of reduced-toxicity myeloablative conditioning (RT-MAC) regimen and the use of partially matched family donors with post-transplantation cyclophosphamide (PT-Cy) have widened the access to Allo-SCT. Antibodies against donor-specific HLA (DSA) increase the risk of engraftment failure in HLA mismatched Allo-SCT. We report the results of five patients with SCD, whereas three with DSA, who underwent an unmanipulated haploidentical stem cell transplantation (Haplo-SCT) after a busulfan-based RT-MAC regimen with PT-Cy. To reduce the risk of engraftment failure, a sequential two courses pharmacological pre-transplant immune suppression (PTIS) phase was added prior to the conditioning regimen. All patients engrafted successfully. The procedure was well tolerated. None of the patients developed acute GVHD, whereas one developed moderate chronic GVHD. After a median follow-up of 5 years (range, 2.2-9), all patients are free of pain with excellent quality of life. Our report shows that Haplo-SCT after a RT-MAC regimen is feasible and safe with stable long-term engraftment and excellent disease control. The risk of graft failure can be abrogated by adding a PTIS phase prior to initiating the conditioning regimen.

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.

The effectiveness of hematopoietic stem cell transplantation in treating pediatric sickle cell disease: Systematic review and meta-analysis

Background

Patients with sickle cell disease (SCD) have just one recognized curative therapy option: hematopoietic stem cell transplantation (HSCT), which results in a long-lasting improvement in the clinical phenotype. Here, we assessed the effectiveness of HSCT in treating children with SCD by a systematic review and meta-analysis.

Methods

Up until January 2024, a comprehensive search was done using Web of Science, CINAHL, Embase, Google Scholar, Cochrane Library, PubMed/Medline, and Embase. Two reviewers worked separately to extract the data, and Newcastle-Ottawa Quality Assessment tool was used to assess the research's quality. The outcomes analyzed were Overall survival (OS), event-free survival (EFS), graft failure (GF) and mortality.

Results

Nineteen papers satisfied our inclusion requirements and were assessed to be of fair quality. The pooled rate of OS was high (92%; 95% CI: 90.3%-93.5%). Similar finding was detected for EFS (85.8%; 95% CI: 83.7%-87.7%). In the other hand, pooled rates of GF and mortality were 6.9% (95% CI: 5.3%-8.9%) and 7.4% (95% CI: 5%-10.7%), respectively. A significant publication bias was detected for OS, EFS and GF outcomes. Subgroups analysis showed that study design was the major source of heterogeneity.

Conclusion

Our results show that HSCT is effective and safe, with pooled survival rates above 90%. It is important to assess innovative tactics in light of the alarming GF and mortality rates.

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.

Outcomes and long-term effects of hematopoietic stem cell transplant in sickle cell disease

INTRODUCTION

Hematopoietic stem cell transplant (HSCT) is the only readily available curative option for sickle cell disease (SCD). Cure rates following human leukocyte antigen (HLA)-matched related donor HSCT with myeloablative or non-myeloablative conditioning are >90%. Alternative donor sources, including haploidentical donor and autologous with gene therapy, expand donor options but are limited by inferior outcomes, limited data, and/or shorter follow-up and therefore remain experimental.

AREAS COVERED

Outcomes are improving with time, with donor type and conditioning regimens having the greatest impact on long-term complications. Patients with stable donor engraftment do not experience SCD-related symptoms and have stabilization or improvement of end-organ pathology; however, the long-term effects of curative strategies remain to be fully established and have significant implications in a patient's decision to seek therapy. This review covers currently published literature on HSCT outcomes, including organ-specific outcomes implicated in SCD, as well as long-term effects.

EXPERT OPINION

HSCT, both allogeneic and autologous gene therapy, in the SCD population reverses the sickle phenotype, prevents further organ damage, can resolve prior organ dysfunction in both pediatric and adult patients. Data support greater success with HSCT at a younger age, thus, curative therapies should be discussed early in the patient's life.

CRISPR/Cas9-based gene-editing technology for sickle cell disease

Sickle cell disease (SCD) is the most common monogenic hematologic disorder and is essentially congenital hemolytic anemia caused by an inherited point mutation in the β-globin on chromosome 11. Although the genetic basis of SCD was revealed as early as 1957, treatment options for SCD have been very limited to date. Hematopoietic stem cell transplantation (HSCT) was thought to hold promise as a cure for SCD, but the available donors were still only 15% useful. Gene therapy has advanced rapidly into the 21st century with the promise of a cure for SCD, and gene editing strategies based on the cluster-based regularly interspaced short palindromic repeat sequence (CRISPR)/Cas9 system have revolutionized the field of gene therapy by precisely targeting genes. In this paper, we review the pathogenesis and therapeutic approaches of SCD, briefly summarize the delivery strategies of CRISPR/Cas9, and finally discuss in depth the current status, application barriers, and solution directions of CRISPR/Cas9 in SCD. Through the review in this paper, we hope to provide some references for gene therapy in SCD.

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.

Controversies and expectations for the prevention of GVHD: A biological and clinical perspective

Severe acute and chronic graft versus host disease (GVHD) remains a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation. Historically, cord blood and matched sibling transplantation has been associated with the lowest rates of GVHD. Newer methods have modified the lymphocyte components to minimize alloimmunity, including: anti-thymocyte globulin, post-transplant cyclophosphamide, alpha/beta T cell depletion, and abatacept. These agents have shown promise in reducing severe GVHD, however, can be associated with increased risks of relapse, graft failure, infections, and delayed immune reconstitution. Nonetheless, these GVHD prophylaxis strategies have permitted expansion of donor sources, especially critical for those of non-Caucasian decent who previously lacked transplant options. This review will focus on the biologic mechanisms driving GVHD, the method by which each agent impacts these activated pathways, and the clinical consequences of these modern prophylaxis approaches. In addition, emerging novel targeted strategies will be described. These GVHD prophylaxis approaches have revolutionized our ability to increase access to transplant and have provided important insights into the biology of GVHD and immune reconstitution.

Emerging approaches to improve allogeneic hematopoietic cell transplantation outcomes for nonmalignant diseases

Many congenital or acquired nonmalignant diseases (NMDs) of the hematopoietic system can be potentially cured by allogeneic hematopoietic cell transplantation (HCT) with varying types of donor grafts, degrees of HLA matching, and intensity of conditioning regimens. Unique features that distinguish the use of allogeneic HCT in this population include higher rates of graft failure, immune-mediated cytopenias, and the potential to achieve long-term disease-free survival in a mixed chimerism state. Additionally, in contrast to patients with hematologic malignancies, a priority is to completely avoid graft-versus-host disease in patients with NMD because there is no theoretical beneficial graft-versus-leukemia effect that can accompany graft-versus-host responses. In this review, we discuss the current approach to each of these clinical issues and how emerging novel therapeutics hold promise to advance transplant care for patients with NMDs.

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.

Hematopoietic Cell Transplantation for Inborn Errors of Immunity Other than Severe Combined Immunodeficiency in Japan: Retrospective Analysis for 1985-2016

PURPOSE

Hematopoietic cell transplantation (HCT) is a curative therapy for most patients with inborn errors of immunity (IEI). We conducted a nationwide study on HCT for patients with IEI other than severe combined immunodeficiency (non-SCID) in Japan.

METHODS

Data from the Japanese national database (Transplant Registry Unified Management Program, TRUMP) for 566 patients with non-SCID IEI, who underwent their first HCT between 1985 and 2016, were retrospectively analyzed.

RESULTS

The 10-year overall survival (OS) and event-free survival (EFS) were 74% and 64%, respectively. The 10-year OS for HCT from unrelated bone marrow (URBM), accounting for 39% of HCTs, was comparable to that for HCT from matched sibling donor (MSD), 79% and 81%, respectively. HCT from unrelated cord blood (URCB), accounting for 28% of HCTs, was also common, with a 10-year OS of 69% but less robust engraftment. The intensity of conditioning was not associated with OS or neutrophil recovery; however, myeloablative conditioning was more frequently associated with infection-related death. Patients who received myeloablative irradiation showed poor OS. Multivariate analyses revealed that HCT in 1985-1995 (hazard ratio [HR], 2.0; P = 0.03), URCB (HR, 2.0; P = 0.01), and related donor other than MSD (ORD) (HR, 2.9; P < 0.001) were associated with poor OS, and URCB (HR, 3.6; P < 0.001) and ORD (HR, 2.7; P = 0.02) showed a higher incidence of retransplantation.

CONCLUSIONS

We present the 1985-2016 status of HCT for non-SCID IEI in Japan with sufficient statistical power, highlighting the potential of URBM as an alternative donor and the feasibility of reduced intensity conditioning.

OUP accepted manuscript

Beta-thalassemia is one of the most common monogenic disorders. Standard treatment of the most severe forms, i.e., transfusion-dependent thalassemia (TDT) with long-term transfusion and iron chelation, represents a considerable medical, psychological, and economic burden. Allogeneic hematopoietic stem cell transplantation from an HLA-identical donor is a curative treatment with excellent results in children. Recently, several gene therapy approaches were evaluated in academia or industry-sponsored clinical trials as alternative curative options for children and young adults without an HLA-identical donor. Gene therapy by addition of a functional beta-globin gene using self-inactivating lentiviral vectors in autologous stem cells resulted in transfusion independence for a majority of TDT patients across different age groups and genotypes, with a current follow-up of multiple years. More recently, promising results were reported in TDT patients treated with autologous hematopoietic stem cells edited with the clustered regularly interspaced short palindromic repeats-Cas9 technology targeting erythroid BCL11A expression, a key regulator of the normal switch from fetal to adult globin production. Patients achieved high levels of fetal hemoglobin allowing for discontinuation of transfusions. Despite remarkable clinical efficacy, 2 major hurdles to gene therapy access for TDT patients materialized in 2021: (1) a risk of secondary hematological malignancies that is complex and multifactorial in origin and not limited to the risk of insertional mutagenesis, (2) the cost—even in high-income countries—is leading to the arrest of commercialization in Europe of the first gene therapy medicinal product indicated for TDT despite conditional approval by the European Medicines Agency.

Hematopoietic cell transplantation for sickle cell disease: updates and future directions

Excellent outcomes in hematopoietic cell transplantation (HCT) from HLA-identical siblings, improvements in conditioning regimens, novel graft-versus-host disease prophylaxis, and the availability of alternative donors have all contributed to the increased applicability and acceptability of HCT for sickle cell disease (SCD). In young children with symptomatic SCD with an available HLA-identical related donor, HCT should be carefully considered. HCT from alternative donors is typically undertaken only in patients with severe symptoms, causing or likely to cause organ damage, and in the context of clinical trials. Patients undergoing HCT for SCD require careful counseling and preparation. They require careful monitoring of unique organ toxicities and complications during HCT. Patients must be prospectively followed for a prolonged time to determine the long-term outcomes and late effects of HCT for SCD. Thus, there is a need for a universal, longitudinal clinical registry to follow patients after HCT for SCD in conjunction with individuals who do not receive HCT to compare outcomes. Antibody-based conditioning and ex-vivo umbilical cord blood expansion are likely to improve the availability and acceptability of HCT. In addition, new disease-modifying drugs and the emerging option of the autologous transplantation of gene-modified hematopoietic progenitor cells are likely to expand the available therapeutic options and make decision-making by patients, physicians, and caregivers even more complicated. Future efforts must also focus on determining the impact of socioeconomic status on access to and outcomes of HCT and the long-term impact of HCT on patients, families, and society.

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.

The Future of Gene Therapy for Transfusion-Dependent Beta-Thalassemia: The Power of the Lentiviral Vector for Genetically Modified Hematopoietic Stem Cells

β-thalassemia, a disease that results from defects in β-globin synthesis, leads to an imbalance of β- and α-globin chains and an excess of α chains. Defective erythroid maturation, ineffective erythropoiesis, and shortened red blood cell survival are commonly observed in most β-thalassemia patients. In severe cases, blood transfusion is considered as a mainstay therapy; however, regular blood transfusions result in chronic iron overload with life-threatening complications, e.g., endocrine dysfunction, cardiomyopathy, liver disease, and ultimately premature death. Therefore, transplantation of healthy hematopoietic stem cells (HSCs) is considered an alternative treatment. Patients with a compatible human leukocyte antigen (HLA) matched donor can be cured by allogeneic HSC transplantation. However, some recipients faced a high risk of morbidity/mortality due to graft versus host disease or graft failure, while a majority of patients do not have such HLA match-related donors. Currently, the infusion of autologous HSCs modified with a lentiviral vector expressing the β-globin gene into the erythroid progenitors of the patient is a promising approach to completely cure β-thalassemia. Here, we discuss a history of β-thalassemia treatments and limitations, in particular the development of β-globin lentiviral vectors, with emphasis on clinical applications and future perspectives in a new era of medicine.

American Society of Hematology 2021 guidelines for sickle cell disease: stem cell transplantation

BACKGROUND

Sickle cell disease (SCD) is a life-limiting inherited hemoglobinopathy that results in significant complications and affects quality of life. Hematopoietic stem cell transplantation (HSCT) is currently the only curative intervention for SCD; however, guidelines are needed to inform how to apply HSCT in clinical practice.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians, and health professionals in their decisions about HSCT for SCD.

METHODS

The multidisciplinary guideline panel formed by ASH included 2 patient representatives and was balanced to minimize potential bias from conflicts of interest. The Mayo Evidence-Based Practice Research Program supported the guideline development process, including performing systematic evidence reviews (through 2019). The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 8 recommendations to help patients and providers assess how individuals with SCD should consider the timing and type of HSCT.

CONCLUSIONS

The evidence review yielded no randomized controlled clinical trials for HSCT in SCD; therefore, all recommendations are based on very low certainty in the evidence. Key recommendations include considering HSCT for those with neurologic injury or recurrent acute chest syndrome at an early age and to improve nonmyeloablative regimens. Future research should include the development of a robust SCD registry to serve as a comparator for HSCT studies.

American Society of Hematology 2021 guidelines for sickle cell disease: stem cell transplantation

BACKGROUND

Sickle cell disease (SCD) is a life-limiting inherited hemoglobinopathy that results in significant complications and affects quality of life. Hematopoietic stem cell transplantation (HSCT) is currently the only curative intervention for SCD; however, guidelines are needed to inform how to apply HSCT in clinical practice.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians, and health professionals in their decisions about HSCT for SCD.

METHODS

The multidisciplinary guideline panel formed by ASH included 2 patient representatives and was balanced to minimize potential bias from conflicts of interest. The Mayo Evidence-Based Practice Research Program supported the guideline development process, including performing systematic evidence reviews (through 2019). The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, including GRADE Evidence-to-Decision frameworks, to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 8 recommendations to help patients and providers assess how individuals with SCD should consider the timing and type of HSCT.

CONCLUSIONS

The evidence review yielded no randomized controlled clinical trials for HSCT in SCD; therefore, all recommendations are based on very low certainty in the evidence. Key recommendations include considering HSCT for those with neurologic injury or recurrent acute chest syndrome at an early age and to improve nonmyeloablative regimens. Future research should include the development of a robust SCD registry to serve as a comparator for HSCT studies.

Optimal umbilical cord blood collection, processing and cryopreservation methods for sustained public cord blood banking

BACKGROUND AIMS

Umbilical cord blood is an established source of stem cells in patients with hematologic malignancies who do not have HLA-compatible matched related or unrelated donors. The success of an umbilical cord blood transplant depends on the dose of total nucleated and CD34+ cells infused. Therefore, collecting, banking and listing high-quality cord blood units with high total nucleated and CD34+ cell dose are essential.

METHODS

Here the authors describe their cord blood bank's novel collection technique, which involves both in utero and ex utero collection of a single cord blood unit. The authors also evaluated maternal, neonatal and collection parameters that may impact the cell dose.

RESULTS

Maternal gestational age and race, and neonatal weight and sex correlated with the total nucleated cell dose.

CONCLUSIONS

The optimized collection of umbilical cord blood is critical for its use as a source of stem cells for transplantation.

Research in Sickle Cell Disease: From Bedside to Bench to Bedside

Sickle cell disease (SCD) is an exemplar of bidirectional translational research, starting with a remarkable astute observation of the abnormally shaped red blood cells that motivated decades of bench research that have now translated into new drugs and genetic therapies. Introduction of hydroxyurea (HU) therapy, the only SCD-modifying treatment for >30 years and now standard care, was initiated through another clinical observation by a pediatrician. While the clinical efficacy of HU is primarily due to its fetal hemoglobin (HbF) induction, the exact mechanism of how it increases HbF remains not fully understood. Unraveling of the molecular mechanism of how HU increases HbF has provided insights on the development of new HbF-reactivating agents in the pipeline. HU has other salutary effects, reduction of cellular adhesion to the vascular endothelium and inflammation, and dissecting these mechanisms has informed bench-both cellular and animal-research for development of the 3 recently approved agents: endari, voxelotor, and crizanlizumab; truly, a bidirectional bench to bedside translation. Decades of research to understand the mechanisms of fetal to adult hemoglobin have also culminated in promising anti-sickling genetic therapies and the first-in-human studies of reactivating an endogenous (γ-globin) gene HBG utilizing innovative genomic approaches.

Allogeneic stem cell transplantation with omidubicel in sickle cell disease

Many patients with sickle cell disease (SCD) do not have HLA-matched related donors for hematopoietic stem cell transplantation (HSCT). Unrelated cord blood (UCB) is an alternative graft option but is historically associated with high graft failure rates, with inadequate cell dose a major limitation. Omidubicel is a nicotinamide-based, ex vivo-expanded UCB product associated with rapid engraftment in adults with hematologic malignancies. We hypothesized that increasing the UCB cell dose with this strategy would lead to improved engraftment in pediatric patients undergoing myeloablative HSCT for SCD. We report the outcomes of a phase 1/2 study in 13 patients with severe SCD who received omidubicel in combination with an unmanipulated UCB graft and 3 who received a single omidubicel graft. Grafts were minimally matched with patients at 4 of 6 HLA alleles. Median age at transplant was 13 years. A median CD34+ expansion of ∼80-fold was observed in omidubicel and led to rapid neutrophil engraftment (median, 7 days). Long-term engraftment was derived from the unmanipulated graft in most of the double cord blood recipients. Two of the 3 single omidubicel recipients also had sustained engraftment. Incidence of acute graft-versus-host disease (GVHD) was high, but resolved in all surviving patients. Event-free survival in the double cord group was 85% (median follow-up 4 years). All 3 patients in the single cord group were alive at 1 year after transplantation. Ex vivo expansion of UCB with omidubicel supports engraftment in patients with SCD. This approach to decreasing the incidence of GVHD should be optimized for general use in patients with SCD. This study was registered at www.clinicaltrials.gov as #NCT01590628.

Abatacept is effective as GVHD prophylaxis in unrelated donor stem cell transplantation for children with severe sickle cell disease

We report results of a phase 1 multicenter stem cell transplantation (SCT) trial from HLA-matched (n = 7) or one-antigen-mismatched (n = 7) unrelated donors (URD) using bone marrow or cord blood as stem cell source, following reduced-intensity conditioning (RIC) in severe sickle cell disease (SCD). Conditioning included distal alemtuzumab, fludarabine, and melphalan (matched donors), with thiotepa (mismatched donors). Abatacept, a selective inhibitor of T cell costimulation, was added to tacrolimus and methotrexate as graft-versus-host disease (GVHD) prophylaxis to offset GVHD risks, and was administered for longer duration in bone marrow recipients than in cord blood recipients because of increased incidence of chronic GVHD with bone marrow. Median age at transplant was 13 years (range, 7-21 years). The incidence of grades II to IV and grades III to IV acute GVHD at day +100 was 28.6% and 7%, respectively. One-year incidence of chronic GVHD was 57% and mild/limited in all but 1 patient who received abatacept for a longer duration. Only 1 patient developed reversible posterior encephalopathy syndrome and recovered. With a median follow-up of 1.6 years (range, 1-5.5 years), the 2-year overall and disease-free survival was 100% and 92.9%, respectively. The encouraging results from the phase 1 portion of this RIC SCT trial, despite risk factors such as older age, URD, and HLA-mismatch, support further evaluation of URD SCT in clinical trial settings. The phase 2 portion of the trial is in progress. This trial was registered at www.clinicaltrials.gov as NCT03128996.

Reduced-intensity single-unit unrelated cord blood transplant with optional immune boost for nonmalignant disorders

Children with many inherited nonmalignant disorders can be cured or their condition alleviated by hematopoietic stem cell transplantation (HSCT). Umbilical cord blood (UCB) units are a rapidly available stem cell source and offer great flexibility in HLA matching, allowing nearly uniform access to HSCT. Although reduced-intensity conditioning (RIC) regimens promise decreased treatment-related morbidity and mortality, graft failure and infections have limited their use in chemotherapy-naive patients. We prospectively evaluated a novel RIC regimen of alemtuzumab, hydroxyurea, fludarabine, melphalan, and thiotepa with a single-unit UCB graft in 44 consecutive patients with inborn errors of metabolism, immunity, or hematopoiesis. In addition, 5% of the UCB graft was re-cryopreserved and reserved for cord donor leukocyte infusion (cDLI) posttransplant. All patients engrafted at a median of 15 days posttransplant, and chimerism was >90% donor in the majority of patients at 1-year posttransplant with only 1 secondary graft failure. The incidence of grade II to IV graft-versus-host disease (GVHD) was 27% (95% confidence interval [CI], 17-43) with no extensive chronic GVHD. Overall survival was 95% (95% CI, 83-99) and 85% (95% CI, 64-93) at 1 and 5 years posttransplant, respectively. No significant end-organ toxicities were observed. The use of cDLI did not affect GVHD and showed signals of efficacy for infection control or donor chimerism. This RIC transplant regimen using single-unit UCB graft resulted in outstanding survival and remarkably low rates of graft failure. Implementation of the protocol not requiring pharmacokinetic monitoring would be feasible and applicable worldwide for children with inherited disorders of metabolism, immunity, or hematopoiesis. This trial was registered at www.clinicaltrials.gov as #NCT01962415.

Emotional labour and cord blood collection: frontline perspectives

PURPOSE

This paper aims to examine emotional labour in the work of frontline staff (FLS) of the Canadian Blood Services' Cord Blood Bank (CBB), contributes to understandings of emotional labour by allied healthcare workers and suggests implications for healthcare managers.

DESIGN/METHODOLOGY/APPROACH

Qualitative interviews with 15 FLS were conducted and analyzed as part of a process evaluation of donor recruitment and cord blood collection in Canada.

FINDINGS

Emotional labour with donors and hospital staff emerged as a vital component of FLS' donor recruitment and cord blood collection work. Emotional labour was performed with donors to contribute to a positive birthing experience, facilitate communication and provide support. Emotional labour was performed with hospital staff to gain acceptance and build relationships, enlist support and navigate hierarchies of authority.

RESEARCH LIMITATIONS/IMPLICATIONS

The results indicate that FLS perform emotional labour with women to provide donor care and with hospital staff to facilitate organizational conditions. The findings are based on FLS' accounts of their work and would be enhanced by research that examines the perspectives of donors and hospital staff.

PRACTICAL IMPLICATIONS

Attention should be paid to organizational conditions that induce the performance of emotional labour and may add to FLS workload. Formal reciprocal arrangements between FLS and hospital staff may reduce the responsibility on FLS and enable them to focus on recruitment and collections.

ORIGINALITY/VALUE

This paper addresses a gap in the healthcare management literature by identifying the emotional labour of allied healthcare workers. It also contributes to the cord blood banking literature by providing empirically grounded analysis of frontline collection staff.

Allogenic hematopoietic stem cell transplantation in sickle cell disease

Sickle cell disease (SCD) is one of the most common monogenic disorders worldwide and affects approximately 100,000 people in the United States alone. SCD can cause numerous complications, including anemia, pain, stroke, and organ failure, which can lead to death. Although there are a few disease-modifying treatments available to patients with SCD, the only current curative option is a hematopoietic stem cell transplant (HSCT). In this review, we will discuss the different approaches to allogeneic HSCT in the treatment of SCD and the outcomes of these approaches.

Hematopoietic Cell Transplantation for Sickle Cell Disease

Sickle cell disease (SCD) is a severe autosomal recessively inherited disorder of the red blood cell characterized by erythrocyte deformation caused by the polymerization of the abnormal hemoglobin, which leads to erythrocyte deformation and triggers downstream pathological changes. These include abnormal rheology, vaso-occlusion, ischemic tissue damage, and hemolysis-associated endothelial dysfunction. These acute and chronic physiologic disturbances contribute to morbidity, organ dysfunction, and diminished survival. Hematopoietic cell transplantation (HCT) from HLA-matched or unrelated donors or haploidentical related donors or genetically modified autologous hematopoietic progenitor cells is performed with the intent of cure or long-term amelioration of disease manifestations. Excellent outcomes have been observed following HLA-identical matched related donor HCT. The majority of SCD patients do not have an available HLA-identical sibling donor. Increasingly, however, they have the option of undergoing HCT from unrelated HLA matched or related haploidentical donors. The preliminary results of transplantation of autologous hematopoietic progenitor cells genetically modified by adding a non-sickling gene or by genomic editing to increase expression of fetal hemoglobin are encouraging. These approaches are being evaluated in early-phase clinical trials. In performing HCT in patients with SCD, careful consideration must be given to patient and donor selection, conditioning and graft-vs.-host disease regimen, and pre-HCT evaluation and management during and after HCT. Sociodemographic factors may also impact awareness of and access to HCT. Further, there is a substantial decisional dilemma in HCT with complex tradeoffs between the possibility of amelioration of disease manifestations and early or late complications of HCT. The performance of HCT for SCD requires careful multidisciplinary collaboration and shared decision making between the physician and informed patients and caregivers.

Matched sibling donor stem cell transplantation for sickle cell disease: Results from the Spanish group for bone marrow transplantation in children

OBJECTIVES

The prevalence of sickle cell disease (SCD) in Spain is markedly inferior compared with other European and Mediterranean countries. However, the diagnosis of new patients with SCD is expected to increase. In this multicenter retrospective study, we analyze the hematopoietic stem cell transplantation (HSCT) results obtained in Spain.

METHODS

Forty-five patients who underwent a matched sibling donor (MSD) HSCT between 1999 and 2018 were included. Primary endpoint was event-free survival (EFS), and secondary endpoints included acute and chronic graft-versus-host disease (GvHD) and overall survival (OS).

RESULTS

Bone marrow was the most frequent stem cell source (93.3%). Most patients received a conditioning regimen based on busulfan and cyclophosphamide (69%). Cumulative incidence of grade III-IV acute GvHD and chronic GvHD was 6.8% (95% CI: 2.3%-20.1%) and 5.4% (95% CI: 1.38%-19.9%), respectively. EFS and overall survival (OS) at 3 years post-HSCT were 89.4% (95% CI: 73.9%-95.9%) and 92.1% (95% CI: 77.2%-97.4%), respectively. All patients aged ≤ 5 presented 100% EFS and OS.

CONCLUSIONS

An early referral to HSCT centers should be proposed early in life, before severe complications occur. MSD HSCT should be considered a curative option for all patients aged ≤ 5 years and for older pediatric patients who present complications derived from the disease.

Transfusion and Cellular Therapy in Pediatric Sickle Cell Disease

Red blood cell (RBC) transfusion is critical in managing acute and chronic complications of sickle cell disease. Alloimmunization and iron overload remain significant complications of transfusion therapy and are minimized with prophylactic Rh and K antigen RBC matching and iron chelation. Matched sibling donor hematopoietic stem cell transplant (HSCT) is a curative therapeutic option. Autologous hematopoietic stem cell (HSC)-based gene therapy has recently shown great promise, for which obtaining sufficient HSCs is essential for success. This article discusses RBC transfusion indications and complications, transfusion support during HSCT, and HSC mobilization and collection for autologous HSCT with gene therapy.

Status quo of allogeneic stem cell transplantation for patients with sickle cell disease using matched unrelated donors

This mini review is based on an oral presentation reflecting the current status quo of allogeneic hematopoietic stem cell transplantation (HSCT) for patients with sickle cell disease (SCD) using matched unrelated donors (MUDs) presented at the EBMT Sickle Disease Meeting held in Regensburg, Germany, in May 2019. Although the clinical trial landscape for MUD HSCT in patients with SCD is limited to date, some attempts to improve patient outcome in terms of overall survival and event-free survival have been made recently, including optimization of conditioning regimens and prevention of engraftment failure as well as graft-versus-host disease. The results achieved by these approaches are summarized in this review and are still unsatisfactory. Whether new haploidentical transplantation protocols will achieve superior results and are able to replace MUD HSCT for patients with SCD remains to be elucidated.

The Phenotype and Functional Activity of Mesenchymal Stromal Cells in Pediatric Patients with Non-Malignant Hematological Diseases

As the biology of mesenchymal stromal cells (MSCs) in patients with non-malignant hematological diseases (NMHD) is poorly understood, in the current study we performed a basic characterization of the phenotype and functional activity of NMHD-MSCs. Bone marrow (BM) of patients with thalassemia major (TM) possessed a significantly higher number of nucleated cells (BM-MNCs)/mL BM than healthy donors (P < 0.0001), which however did not result in a higher number of colony forming units-fibroblast (CFU-F) per milliliter BM. In contrast, from 1 × 10⁶ BM-MNCs of patients with sickle cell disease (SCD) were generated significantly more CFU-Fs than from TM-BM-MNCs (P < 0.013) and control group (P < 0.02). In addition, NMHD-MSCs expressed significantly lower levels of CD146 molecule, demonstrated an equal proliferation potential and differentiated along three lineages (osteoblasts, chondrocytes and adipocytes) as healthy donors’ MSCs, with exception of TM-MSCs which differentiated weakly in adipocytes. In contrast to other NMHD-MSCs and healthy donors’ MSCs, TM-MSCs demonstrated an impaired in vitro immunosuppressive potential, either. Noteworthy, the majority of the immunosuppressive effect of NMHD-MSCs was mediated through prostaglandin-E2 (PGE2), because indomethacin (an inhibitor of PGE2 synthesis) was able to significantly reverse this effect. Our results indicate therefore that NMHD-MSCs, except TM-MSCs, may be used as an autologous cell-based therapy for post-transplant complications such as graft failure, graft-versus-host disease (GvHD) and osteonecrosis.

How I treat sickle cell disease with hematopoietic cell transplantation

Sickle cell disease (SCD) leads to significant morbidity and early mortality, and hematopoietic cell transplantation (HCT) is the only widely available cure, with impacts seen on SCD-related organ dysfunction. Outcomes are excellent following matched-related donor (MRD) HCT, leading to significantly expanded application of this treatment over the past decade. The majority of SCD patients lack an MRD, but outcomes following alternative donor HCT continue to improve on clinical trials. Within this framework, we aim to provide our perspective on how to apply research findings to clinical practice, for an individual patient. We also emphasize that the preparation of SCD recipients for HCT and supporting them through HCT have special nuances that require awareness and close attention. Through the use of clinical vignettes, we provide our perpsective on the complex decision-making process in HCT for SCD as well as recommendations for the evaluation and support of these patients through HCT.

Choice of Donor Source and Conditioning Regimen for Hematopoietic Stem Cell Transplantation in Sickle Cell Disease

In the United States, one out of every 500 African American children have sickle cell disease (SCD), and SCD affects approximately 100,000 Americans. Significant advances in the treatment of this monogenetic disorder have failed to substantially extend the life expectancy of adults with SCD over the past two decades. Hematopoietic stem cell transplantation (HSCT) remains the only curative option for patients with SCD. While human leukocyte antigen (HLA) matched sibling HSCT has been successful, its availability is extremely limited. This review summarizes various conditioning regimens that are currently available. We explore recent efforts to expand the availability of allogeneic HSCT, including matched unrelated, umbilical cord blood, and haploidentical stem cell sources. We consider the use of nonmyeloablative conditioning and haploidentical donor sources as emerging strategies to expand transplant availability, particularly for SCD patients with complications and comorbidities who can undergo neither matched related transplant nor myeloablative conditioning. Finally, we show that improved conditioning agents have improved success rates not only in the HLA-matched sibling setting but also alternative donor settings.

Human Leukocyte Antigen and Red Blood Cells Impact Umbilical Cord Blood CD34+ Cell Viability after Thawing

Hematopoietic progenitor cell (HPC) transplantation is a treatment option for malignant and nonmalignant diseases. Umbilical cord blood (UCB) is an important HPC source, mainly for pediatric patients. It has been demonstrated that human leukocyte antigen (HLA) matching and cell dose are the most important features impacting clinical outcomes. However, UCB matching is performed using low resolution HLA typing and it has been demonstrated that the unnoticed mismatches negatively impact the transplant. Since we found differences in CD34+ viability after thawing of UCB units matched for two different patients (p = 0.05), we presumed a possible association between CD34+ cell viability and HLA. We performed a multivariate linear model (n = 67), comprising pre-cryopreservation variables and high resolution HLA genotypes separately. We found that pre-cryopreservation red blood cells (RBC), granulocytes, and viable CD34+ cell count significantly impacted CD34+ viability after thawing, along with HLA-B or -C (R2 = 0.95, p = 0.01; R2 = 0.56, p = 0.007, respectively). Although HLA-B*40:02 may have a negative impact on CD34+ cell viability, RBC depletion significantly improves it.

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.

Curative Therapies for Sickle Cell Disease

Background: Sickle cell disease (SCD) is an inherited hemoglobinopathy associated with severe morbidity, impaired quality of life, and premature mortality. Hematopoietic stem cell transplantation (HSCT) is the only curative treatment available for patients with SCD and has a >90% event-free survival when a matched related donor is used. However, availability of human leukocyte antigen (HLA)-identical sibling donors for the SCD population is limited. The use of HLA-matched unrelated donors or related haploidentical donors has the potential to expand the donor pool. Methods: We reviewed the current literature on the indications for SCD transplantation, donor options, and the emerging use of gene therapy as a treatment option. Google Scholar and PubMed were searched using the terms SCD, bone marrow transplantation, donor sources, gene therapy, HSCT, and HLA matching. Additional articles were identified from the bibliographies of retrieved articles. All articles were reviewed for pertinent information related to SCD and transplantation. Results: HSCT has the potential to establish donor-derived normal erythropoiesis with stable long-term engraftment, amelioration of symptoms, and stabilization of organ damage. The majority of HSCT has been performed in children from HLA-identical sibling donors and has resulted in excellent rates of survival. The use of alternate donors such as HLA-matched unrelated donors and haploidentical donors has the potential to expand the applicability of HSCT for SCD. Early results in gene therapy for SCD are encouraging. Conclusion: Evaluation of the long-term benefits of curative therapies for SCD requires comparative clinical trials and studies of late effects.

Contextual factors influencing donor recruitment and cord blood collection: perspectives of frontline staff of the Canadian Blood Services' Cord Blood Bank

BACKGROUND

Umbilical cord blood (CB) is an important source of hematopoietic stem cells that are used to treat blood- and immune-system disorders. Public CB banks aim to build inventories with high-quality CB units to meet healthcare needs. While research has noted the influence of broader contextual factors on donor recruitment and CB collection processes, to date, no published study has identified the specific contextual factors and challenges to donor recruitment and CB collection. This paper addresses this gap in the literature.

STUDY DESIGN AND METHODS

A qualitative case study focusing on donor recruitment and CB collection processes was conducted to identify the contextual factors influencing these processes. This paper reports the findings from in-depth, semi-structured interviews conducted with 15 frontline staff of the Canadian Blood Services' Cord Blood Bank. Interview data were analyzed using inductive interpretive methods to identify the contextual conditions and factors that influence recruitment and collection.

RESULTS

Frontline staff described various social factors that influenced and challenged the processes of donor recruitment and CB collection. These were categorized into four overlapping contexts: birthing context, hospital context, CB bank organizational context, and sociocultural context.

CONCLUSION

Consideration of social context is necessary in order to effectively address the factors and challenges that influence the successful development of high-quality CB inventories, and to guide resource allocation. Further examination of contextually-rooted factors and their interactions is necessary to optimize donor recruitment and CB collection processes.

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.

Reduction in Mortality after Umbilical Cord Blood Transplantation in Children Over a 20-Year Period (1995-2014)

Infections and graft-versus-host disease (GVHD) have historically resulted in high mortality among children undergoing umbilical cord blood transplantation (UCBT). However, recent advances in clinical practice have likely improved outcomes of these patients. We conducted a retrospective cohort study of children (<18years of age) undergoing UCBT at Duke University between January 1, 1995 and December 31, 2014. We compared 2-year all-cause and cause-specific mortality during 3 time periods based on year of transplantation (1995 to 2001, 2002 to 2007, and 2008 to 2014). We used multivariable Cox regression to identify demographic and UCBT characteristics that were associated with all-cause mortality, transplantation-related mortality, and death from invasive aspergillosis after adjustment for time period. During the 20-year study period 824 children underwent UCBT. Two-year all-cause mortality declined from 48% in 1995 to 2001 to 30% in 2008 to 2014 (P = .0002). White race and nonmalignant UCBT indications were associated with lower mortality. Black children tended to have a higher risk of death for which GVHD (18% versus 11%; P = .06) or graft failure (9% versus 3%; P = .01) were contributory than white children. Comparing 2008 to 2014 with 1995 to 2001, more than half (59%) of the reduced mortality was attributable to a reduction in infectious mortality, with 45% specifically related to reduced mortality from invasive aspergillosis. Antifungal prophylaxis with voriconazole was associated with lower mortality from invasive aspergillosis than low-dose amphotericin B lipid complex (hazard ratio, .09; 95% confidence interval, .01 to .76). With the decline in mortality from invasive aspergillosis, adenovirus and cytomegalovirus have become the most frequentinfectious causes of death in children after UCBT. Advances in clinical practice over the past 20years improved survival of children after UCBT. Reduced mortality from infections, particularly invasive aspergillosis, accounted for the largest improvement in survival and was associated with use of voriconazole for antifungal prophylaxis.

Allogeneic hematopoietic stem cell transplantation in congenital hemoglobinopathies with myeloablative conditioning and rabbit anti-thymocyte globulin

Background

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative therapy for β-thalassemia major (TM) and sickle cell disease (SCD) in children. Graft-versus-host disease (GVHD) and treatment-related mortality (TRM) remain significant challenges to improving survival after HSCT. Here, we analyzed the outcome of TM and SCD patients, who received allogeneic HSCT with myeloablative conditioning at our institution.

Methods

Twenty-two patients (15 TM, 7 SCD), with a median age of 9 years (range, 1.6–16.9), underwent allogeneic HSCT using busulfan, cyclophosphamide and rabbit anti-thymocyte globulin-based conditioning. Cells were derived from either the bone marrow (8 patients), or peripheral blood stem cells (14 patients). The majority of patients received HSCT from a matched sibling donor (N=18). GVHD prophylaxis included cyclosporine and short course methotrexate.

Results

All patients achieved donor engraftment. Two SCD patients died from TRM-related grade IV gut GVHD (N=1) or severe bronchiolitis obliterans (BO) (N=1). Cumulative incidence of acute and chronic GVHD was 36.4% and 32.7%, respectively. Veno-occlusive disease (VOD) occurred in 8 patients (36.4%), but resolved in all instances. Epstein-Barr virus (EBV)-related post-transplantation lymphoproliferative disease (PTLD) occurred in 1 patient. The overall survival (OS) was 90.9% (TM 100%, SCD 71.4%), with all patients achieving transfusion independence, while 8 achieved complete donor chimerism.

Conclusion

Busulfan, cyclophosphamide, and ATG-based conditioning for HSCT of TM and SCD patients did not result in graft failure, although modifications may be required to reduce VOD incidence. Further changes to donor type and cell source prioritization are necessary to minimize TRM and morbidity caused by GVHD.

Stem cell transplantation in sickle cell disease: therapeutic potential and challenges faced

INTRODUCTION

Sickle cell disease (SCD) is the most common inherited hemoglobinopathy worldwide, and is a life-limiting disease with limited therapeutic options to reduce disease severity. Despite being a monogenic disorder, the clinical phenotypes of SCD are variable, with few reliable predictors of disease severity easily identifying patients where the benefits of curative therapy outweigh the risks. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative option, though significant advances in gene therapy raise the promise for additional curative methods. Areas covered: Allogeneic transplantation in SCD has evolved and improved over the last two decades, now offering a standard of care curative option using a human leukocyte antigen (HLA)-matched sibling donor. Many of the seminal transplantation studies are reviewed here, demonstrating how initial failures and successes have influenced and led to current HSCT strategies. Such strategies aim to overcome setbacks and limitations, and focus on conditioning regimens, immune suppression methods, the use alternative donor sources, and gene therapy approaches. Expert commentary: SCD is a curable disease. Each dedicated effort to refine transplantation methods, expand the donor pool, and bring gene therapy models to fruition will make enormous impacts reducing disease burden and improving outcomes and quality of life for patients with SCD.

Modified conditioning regimen improves outcomes of unrelated donor peripheral blood stem cell transplantation for β-thalassaemia major patients

BACKGROUND

The objective of this study was to evaluate the feasibility of a modified conditioning regimen for the treatment of patients with β-thalassaemia major (TM), using unrelated donor peripheral blood stem cell transplantation (UD-PBSCT).

METHODS

A modified conditioning regimen based on intravenous busulfan, cyclophosphamide, fludarabine, and antithymocyte globulin was performed in 50 consecutive childhood patients with β-TM and a median age of 4.6 years (range, 2-12 years). According to Pesaro's classification, three classes of risk are identified using the criteria of degree of hepatomegaly, portal fibrosis, and quality of the chelation treatment. Patients with three adverse criteria constituted class III, none of the adverse criteria constituted class I, and one or two of the adverse criteria formed class II. Ten patients were class I, 36 class II, and four class III. All patients were transplanted with UDs containing 37 of 10/10 human leukocyte antigen (HLA)-matched pairs, 11 of 9/10 matched pairs, and two of 8/10 matched pairs. The median follow-up was 36 months (range, 9-96 months).

RESULTS

All patients successfully achieved engraftment, two of whom developed persistent thrombocytopaenia. The incidence of acute graft-versus-host disease (aGVHD) grade III-IV and chronic graft-versus-host disease (cGVHD) were 12% and 8%, respectively. However, 8.3% of HLA-matched and 15.4% of HLA-mismatched patients developed aGVHD. The incidence of severe bacterial infections and fungal pneumonia was 12% and 20%, respectively. The 3-year overall survival, disease-free survival, graft rejection, and transplant-related mortality were 94%, 92%, 2%, and 6%, respectively.

CONCLUSION

This modified conditioning protocol effectively improved outcomes of UD-PBSCT for patients with β-TM.

Umbilical Cord Blood Transplantation Corrects Very Early-Onset Inflammatory Bowel Disease in Chinese Patients With IL10RA-Associated Immune Deficiency

BACKGROUND

Hematopoietic stem cell transplantation is considered the only curative therapy for very early-onset inflammatory bowel disease with specific immune defects, such as interleukin-10 receptor deficiency. We performed reduced-intensity conditioning before umbilical cord blood transplantation in patients with interleukin-10 receptor-A deficiency.

METHODS

We enrolled 9 very early-onset inflammatory bowel disease patients with typical manifestations. We diagnosed the patients with interleukin-10 receptor-A deficiency by whole-exome sequencing. Umbilical cord blood transplantation was performed in all 9 patients. Eight patients received the reduced-intensity conditioning regimen, and 1 patient received the myeloablative conditioning regimen.

RESULTS

All 9 patients received transplantation between the ages of 6 months to 43 months (average, 16.8 months) with body weights ranging from 3 to 10.4 kg (average, 6.6 kg). The patients displayed complete chimerism at 2-8 weeks after transplantation; 6 patients achieved complete remission without evidence of graft-vs-host disease or infections; 1 patient died of chronic lung graft-vs-host disease at 6 months post-transplantation; and the other 2 patients died of sepsis post-transplantation because of unsuccessful engraftments. Severe malnutrition and growth retardation associated with interleukin-10 receptor-A deficiency were significantly improved post-transplantation.

CONCLUSIONS

We recommend umbilical cord blood transplantation as a potential treatment for very early-onset inflammatory bowel disease with a defined monogenic immunodeficiency, and we suggest that reduced-intensity conditioning chemotherapy is more suitable than myeloablative conditioning for patients with severe malnutrition and bowel disease. We have demonstrated success with reduced-intensity conditioning for interleukin-10 receptor-A deficiency in pediatric patients with severe clinical conditions. 10.1093/ibd/izy028_video1izy028.video15786489183001.