Outcome of patients with hemoglobinopathies given either cord blood or bone marrow transplantation from an HLA-identical sibling. Blood. 2013;122:1072-1078. [PMID: 23692854 DOI: 10.1182/blood-2013-03-489112]

Selecting patients with sickle cell disease for gene addition or gene editing-based therapeutic approaches: Report on behalf of a joint EHA Specialized Working Group and EBMT Hemoglobinopathies Working Party consensus conference

Sickle cell disease (SCD) remains associated with reduced life expectancy and poor quality of life despite improvements observed in the last decades mostly related to comprehensive care, use of hydroxycarbamide, screening to identify patients at risk of strokes, and implementation of safe transfusion protocols. The course of the disease is highly variable, making it difficult to predict severity and response to therapy. Allogeneic hematopoietic stem cell transplantation potentially provides a cure with a relatively low rate of complications, but few patients have an HLA-identical sibling. The hopes of patients and healthcare providers have been raised after the initial excellent results of gene therapy studies. However, there is a strong contrast between the high expectations of families and patients and the limited availability of the product, which is technically complex and very expensive. In light of this consideration and of the limited data available on the long-term efficacy and toxicity of different gene therapy approaches, the European Hematology Association Red Cell & Iron Specialized Working Group (EHA SWG) and the hemoglobinopathy working part of the European Blood & Marrow Transplant (EBMT) Group have prioritized the development of recommendations for selection of patients with SCD who are good candidates for gene therapy. The decision-making algorithm was developed by a panel of experts in hemoglobinopathies and/or transplantation chosen by EHA SWG and EBMT, to discuss the selection of SCD patients for gene therapy and draw notes on the related clinical problems.

A phase 2 pilot study of umbilical cord blood infusion as an adjuvant consolidation therapy in elderly patients with acute myeloid leukemia

Acute myeloid leukemia (AML) is an aging-related malignancy, with patients aged ≥60 years old facing significantly poorer prognosis. Umbilical cord blood (UCB) has emerged as a promising source with effective anti-aging roles. Here, we conducted a prospective, phase 2, single-arm trial of UCB infusion as an adjuvant consolidation therapy in elderly AML patients (ChiCTR-OPC-15006492). A total of 51 patients were enrolled (median age 66 years; range, 60-75) and received two cycles of consolidation chemotherapy combined with UCB infusion. At a median follow-up of 27.3 months (range, 9.3-100), the median overall survival (OS) was not yet reached and the median event-free survival (EFS) was 72.2 months (range, 5.4-100). The 2-year OS and EFS rates were 76.9% and 62.8%, respectively. No acute graft-versus-host disease (aGVHD) or toxicity-related death occurred in any patient. The median times to platelet and neutrophil recovery were 11.5 days (range, 6-17) and 12.2 days (range, 0-21), respectively. Single-cell RNA sequencing (scRNA-seq) identified enhanced anti-tumor and anti-aging properties of UCB, manifested through activation of immune responses and telomere synthesis/maintenance. These findings suggest that UCB infusion is an effective and safe post-remission adjuvant therapy for elderly AML patients. This study provides evidence that anti-aging therapy may serve as a new and promising dimension in combined cancer treatment.

Hematopoietic Stem Cell Transplantation in Children with Sickle Cell Disease and Thalassemia Major: A National Database Study

In patients with sickle cell disease (SCD) and beta-thalassemia major (TM), allogeneic hematopoietic stem cell transplantation (HSCT) was considered the only curative treatment option with a good survival rate. However, with the recent approval of gene therapies, more information is needed to understand the benefits and risks of these interventions. We performed a retrospective analysis of the Kids Inpatient Database to describe demographic features, short-term complications, and hospital charges of patients with SCD and TM treated with HSCT during 2006-2019 in the United States. The database was filtered using the International Classification of Diseases, 9th and 10th edition codes to identify children under 20 years of age with SCD or TM who underwent HSCT. A total of 513 children with SCD or TM who received HSCT were analyzed. The prevalence of HSCT per 1000,000 U.S. population increased from 0.31 in 2006 to 1.99 in 2019 (p < 0.001). The median age of children with SCD who underwent HSCT was 10 (6-15) years, and that for TM was 6 (3-11.5) years (p < 0.001). The combined mortality rate was 4% (2.4%-6.6%) but higher in the TM group. The length-of-stay and total charges were higher in the TM population (p < 0.01). This study provides national data on HSCT among hospitalized children with SCD and TM in the United States, demonstrating an increasing use of HSCT between 2006 and 2019. Although hospital mortality of HSCT in these conditions is low, it still represents a challenge, especially in TM patients.

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.

Assistance of next-generation sequencing for diagnosis of disseminated Bacillus Calmette-Guerin disease with X-SCID in an infant: a case report and literature review

Bacille Calmette-Guérin (BCG) is a live strain of Mycobacterium bovis (M.bovis) for use as an attenuated vaccine to prevent tuberculosis (TB) infection, while it could also lead to an infection in immunodeficient patients. M.bovis could infect patients with immunodeficiency via BCG vaccination. Disseminated BCG disease (BCGosis) is extremely rare and has a high mortality rate. This article presents a case of a 3-month-old patient with disseminated BCG infection who was initially diagnosed with hemophagocytic syndrome (HPS) and eventually found to have X-linked severe combined immunodeficiency (X-SCID). M.bovis and its drug resistance genes were identified by metagenomics next-generation sequencing (mNGS) combined with targeted next-generation sequencing (tNGS) in blood and cerebrospinal fluid. Whole exome sequencing (WES) revealed a pathogenic variant in the common γ-chain gene (IL2RG), confirming X-SCID. Finally, antituberculosis therapy and umbilical cord blood transplantation were given to the patient. He was successfully cured of BCGosis, and his immune function was restored. The mNGS combined with the tNGS provided effective methods for diagnosing rare BCG infections in children. Their combined application significantly improved the sensitivity and specificity of the detection of M.bovis.

An update review of new therapies in sickle cell disease: the prospects for drug combinations

INTRODUCTION

Sickle cell disease (SCD) is an inherited disorder characterised by polymerisation of deoxygenated haemoglobin S and microvascular obstruction. The cardinal feature is generalised pain referred to as vaso-occlusive crises (VOC), multi-organ damage and premature death. SCD is the most prevalent inherited life-threatening disorders in the world and over 85% of world's 400,000 annual births occur low-and-middle-income countries. Hydroxyurea remained the only approved disease modifying therapy (1998) until the FDA approved L-glutamine (2017), Crizanlizumab and Voxelotor (2019) and gene therapies (Exa-cel and Lovo-cel, 2023).

AREAS COVERED

Clinical trials performed in the last 10 years (November 2013 - November 2023) were selected for the review. They were divided according to the mechanisms of drug action. The following pubmed central search terms [sickle cell disease] or [sickle cell anaemia] Hydroxycarbamide/ Hydroxyurea, L-Glutamine, Voxelotor, Crizanlizumab, Mitapivat, Etavopivat, gene therapy, haematopoietic stem cell transplantation, and combination therapy.

EXPERT OPINION

We recommend future trials of combination therapies for specific complications such as VOCs, chronic pain and renal impairment as well as personalised medicine approach based on phenotype and patient characteristics. Following recent approval of gene therapy for SCD, the challenge is addressing the role of shared decision-making with families, global access and affordability.

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.

Engineering of the endogenous HBD promoter increases HbA2

The β-hemoglobinopathies, such as sickle cell disease and β-thalassemia, are one of the most common genetic diseases worldwide and are caused by mutations affecting the structure or production of β-globin subunits in adult hemoglobin. Many gene editing efforts to treat the β-hemoglobinopathies attempt to correct β-globin mutations or increase γ-globin for fetal hemoglobin production. δ-globin, the subunit of adult hemoglobin A2, has high homology to β-globin and is already pan-cellularly expressed at low levels in adult red blood cells. However, upregulation of δ-globin is a relatively unexplored avenue to increase the amount of functional hemoglobin. Here, we use CRISPR-Cas9 to repair non-functional transcriptional elements in the endogenous promoter region of δ-globin to increase overall expression of adult hemoglobin 2 (HbA2). We find that insertion of a KLF1 site alone is insufficient to upregulate δ-globin. Instead, multiple transcription factor elements are necessary for robust upregulation of δ-globin from the endogenous locus. Promoter edited HUDEP-2 immortalized erythroid progenitor cells exhibit striking increases of HBD transcript, from less than 5% to over 20% of total β-like globins in clonal populations. Edited CD34 +hematopoietic stem and progenitors (HSPCs) differentiated to primary human erythroblasts express up to 46% HBD in clonal populations. These findings add mechanistic insight to globin gene regulation and offer a new therapeutic avenue to treat β-hemoglobinopathies.

The Present Condition of Sickle Cell Disease: An Overview of Stem Cell Transplantation as a Cure

Treatment of sickle cell disease (SCD) remains largely palliative. While it can enhance living standards, persons having SCD still suffer from extreme sickling crises, end-organ destruction, and reduced life expectancy. Increasing research has resulted in the recognition and advancement of stem cell transplantation and gene therapy as possible solutions for SCDs. However, there have been various factors that have hindered their clinical application. The more advantageous of the two, stem cell transplantation, is constrained by a small donor pool, transplant difficulties, and eligibility requirements. The current article reviewed the literature on SCDs, current treatment options, and more particularly the progress of stem cell transplants. It outlined various challenges of stem cell transplant and proposed ways to increase the donor pool using alternative strategies and modifications of regimen conditioning with minimal transplant-related toxicities and associated complications.

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.

Addition of ruxolitinib in Graft-versus-Host disease prophylaxis for pediatric β-Thalassemia major patients after allogeneic stem cell transplantation: A retrospective cohort study

BACKGROUND

To evaluate the effect of addition of ruxolitinib in Graft-versus-Host Disease (GVHD) prophylaxis on pediatric patients with β-thalassemia major after allogeneic hematopoietic stem cell transplantation(HSCT).

METHODS

This retrospective study reviewed 49 consecutive β-thalassemia major pediatric patients who underwent HSCT from unrelated or haploidentical donors from February 2018 to October 2022. All transplantation recipients received cyclosporine A (CsA), mycophenolate mofetil (MMF), and short-term methotrexate (MTX) as GVHD prophylaxis; while 27 of them in the ruxolitinib group had added ruxolitinib oral to GVHD prophylaxis regimen at 2.5 mg twice daily once successful engraftment after January 2020.

RESULTS

The outcome showed that the ruxolitinib group had a lower cumulative incidence than the control group regardless of acute GVHD (22.2% vs.40.9%; p = .153) or chronic GVHD (18.5% vs.40.9%; p = .072); especially, the incidence of grade III-IV acute GVHD was reported significantly less frequently in ruxolitinib group than that of the control group (0 vs. 27.3%, p = .005). No significant difference was detected between the two groups in EBV (Epstein-Barr virus)/CMV (cytomegalovirus) reactivation and BKV (BK virus) infection (p = .703, 1.000, and .436, respectively). Twenty-six patients (96.3%) in the ruxolitinib group were alive, while two patients (9.1%) in the control group died of intestinal acute GVHD. The 2-year overall survival (OS) and thalassemia-free survival (TFS) were both 96.296% in the ruxolitinib group, while both 90.909% in the control group.

CONCLUSION

This study reveals that ruxolitinib prophylaxis is a promising option to decrease the incidence of grade III-IV acute GVHD in pediatric patients with β-thalassemia major.

Clinical Outcomes of Umbilical Cord Blood Transplantation Using Ex Vivo Expansion: A Systematic Review and Meta-Analysis of Controlled Studies

Greater use of umbilical cord blood (UCB) for hematopoietic cell transplantation (HCT) is limited by the number of cells in banked units. Ex vivo culture strategies have been increasingly evaluated in controlled studies, but their impact on transplantation-related outcomes remains uncertain owing to the small patient numbers in these studies, necessitating an updated systematic review and meta-analysis. A systematic literature search was conducted using the MEDLINE, Embase, and Cochrane databases to March 18, 2022. Nine cohort-controlled phase I to III trials were identified, and data of 1146 patients undergoing umbilical cord blood transplantation (UCBT) were analyzed (308 ex vivo expanded and 838 unmanipulated controls). Expansion strategies involved cytokine cocktails plus the addition of small molecules (UM171, nicotinamide [NiCord], copper chelation, Notch ligand, or Stem regenin-1 [SR-1]) and coculture with mesenchymal stromal cells in a single-unit transplant strategy (5 studies) or a double-unit transplant strategy with 1 unmanipulated unit (4 studies). The included trials reported a median ex vivo expansion of CD34⁺ cells from 28-fold to 330-fold. Eight of the 9 studies demonstrated a significantly faster time to initial neutrophil and platelet engraftment using expanded cells compared with controls. Studies using UM171 and NiCord in single-unit UCBT and SR-1 or NiCord double-unit UCBT demonstrated long-term donor chimerism of the expanded unit at 100 days to 36 months post-transplantation in all single-unit recipients and in 35% to 78% of double-unit recipients. Our meta-analysis revealed a lower risk of death at the study endpoint in patients who received ex vivo expanded grafts (odds ratio [OR], .66; 95% confidence interval [CI], .47 to .95; P = .02), while the risk of grade II-IV acute graft-versus-host disease was unchanged (OR, .79; 95% CI, .58 to 1.08; P = .14). This review indicates that UCBT following ex vivo expansion can accelerate initial engraftment. Durable donor chimerism can be achieved after transplanting cord blood units expanded using NiCord, UM171, or SR-1; however, long term outcomes remain unclear. Larger studies with longer-term outcomes are needed to better understand the merits of specific expansion strategies on survival.

Transplant for non-malignant disorders: an International Society for Cell & Gene Therapy Stem Cell Engineering Committee report on the role of alternative donors, stem cell sources and graft engineering

Hematopoietic stem cell transplantation (HSCT) is curative for many non-malignant disorders. As HSCT and supportive care technologies improve, this life-saving treatment may be offered to more and more patients. With the development of new preparative regimens, expanded alternative donor availability, and graft manipulation techniques, there are many options when choosing the best regimen for patients. Herein the authors review transplant considerations, transplant goals, conditioning regimens, donor choice, and graft manipulation strategies for patients with non-malignant disorders undergoing HSCT.

How I prevent GVHD in high-risk patients: posttransplant cyclophosphamide and beyond

Advances in conditioning, graft-versus-host disease (GVHD) prophylaxis and antimicrobial prophylaxis have improved the safety of allogeneic hematopoietic cell transplantation (HCT), leading to a substantial increase in the number of patients transplanted each year. This influx of patients along with progress in remission-inducing and posttransplant maintenance strategies for hematologic malignancies has led to new GVHD risk factors and high-risk groups: HLA-mismatched related (haplo) and unrelated (MMUD) donors; older recipient age; posttransplant maintenance; prior checkpoint inhibitor and autologous HCT exposure; and patients with benign hematologic disorders. Along with the changing transplant population, the field of HCT has dramatically shifted in the past decade because of the widespread adoption of posttransplantation cyclophosphamide (PTCy), which has increased the use of HLA-mismatched related donors to levels comparable to HLA-matched related donors. Its success has led investigators to explore PTCy's utility for HLA-matched HCT, where we predict it will be embraced as well. Additionally, combinations of promising new agents for GVHD prophylaxis such as abatacept and JAK inhibitors with PTCy inspire hope for an even safer transplant platform. Using 3 illustrative cases, we review our current approach to transplantation of patients at high risk of GVHD using our modern armamentarium.

Donor chimerism and immune reconstitution following haploidentical transplantation in sickle cell disease

Introduction

We previously reported the initial results of a phase II multicenter transplant trial using haploidentical parental donors for children and aolescents with high-risk sickle cell disease achieving excellent survival with exceptionally low rates of graft-versus-host disease and resolution of sickle cell disease symptoms. To investigate human leukocyte antigen (HLA) sensitization, graft characteristics, donor chimerism, and immune reconstitution in these recipients.

Methods

CD34 cells were enriched using the CliniMACS^® system with a target dose of 10 x 10⁶ CD34⁺ cells/kg with a peripheral blood mononuclear cell (PBMNC) addback dose of 2x10⁵ CD3/kg in the final product. Pre-transplant HLA antibodies were characterized. Donor chimerism was monitored 1-24 months post-transplant. Comprehensive assessment of immune reconstitution included lymphocyte subsets, plasma cytokines, complement levels, anti-viral T-cell responses, activation markers, and cytokine production. Infections were monitored.

Results

HLA antibodies were detected in 7 of 11 (64%) evaluable patients but rarely were against donor antigens. Myeloid engraftment was rapid (100%) at a median of 9 days. At 30 days, donor chimerism was 93-99% and natural killer cell levels were restored. By 60 days, CD19 B cells were normal. CD8 and CD4 T-cells levels were normal by 279 and 365 days, respectively. Activated CD4 and CD8 T-cells were elevated at 100-365 days post-transplant while naïve cells remained below baseline. Tregs were elevated at 100-270 days post-transplant, returning to baseline levels at one year. At one year, C3 and C4 levels were above baseline and CH50 levels were near baseline. At one year, cytokine levels were not significantly different from baseline.

Discussion

These results suggest that haploidentical transplantation with CD34-enriched cells and peripheral blood mononuclear cell addback results in rapid engraftment, sustained donor chimerism and broad-based immune reconstitution.

Haplo-Peripheral Blood Stem Cell Plus Cord Blood Grafts for Hematologic Malignancies Might Lead to Lower Relapse Compared with Haplo-Peripheral Blood Stem Cell Plus Bone Marrow Grafts

To compare the outcomes between peripheral blood stem cell (PBSC)+cord blood and PBSC+bone marrow (BM) grafts in the setting of haploidentical donor (HID) transplantation, 110 patients were enrolled in this retrospective study, including 54 recipients of haplo-PBSC+cord transplants and 56 recipients of haplo-PBSC+BM transplants. Chimerism analyses revealed that by day 30 post-transplantation, 94.3% of surviving patients in the haplo-PBSC+cord group had achieved full haploidentical chimerism and 5.7% had <10% cord chimerism, whereas 100% of surviving patients in the haplo-PBSC+BM group had achieved full donor chimerism. The cumulative incidence of platelet engraftment at 30 days was 92.6% in the haplo-PBSC+cord group versus 89.3% in the haplo-PBSC+BM group (P =.024), that of grade II-IV acute graft-versus-host disease (GVHD) at 100 days was 31.5% versus 48.2% (P =.060), and 1-year relapse was 13.0% versus 25.0% (P =.027), nonrelapse mortality was 9.3% versus 12.5% (P =.76), disease-free survival (DFS) was 77.7% versus 62.5% (P =.028), and overall survival (OS) was 81.4% versus 69.6% (P =.046). Multivariate analysis identified haplo-PBSC+cord transplantation as a protective factor for relapse (hazard ratio [HR], .31; P =.007), DFS (HR, .40; P =.007), and OS (HR, .44; P =.016). Overall, haplo-PBSC+cord transplantation led to faster platelet engraftment, lower relapse, and superior DFS and OS compared with haplo-PBSC+BM transplantation and thus might be a better transplant mode in the setting of HID transplantation.

The effect of intensity of conditioning regimen on the outcome of HSCT in children with sickle cell disease

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) provides a cure for patients with sickle cell disease (SCD). This study describes the effect of conditioning regimen intensity on HSCT outcomes among children younger than 14 years with SCD.

METHODS

Transplants from HLA-matched related donors (MRD) and unrelated donors (MUD) using either myeloablative conditioning (MAC) regimens or reduced intensity conditioning (RIC) regimens were considered. Event-free survival (EFS) was the primary endpoint. Secondary endpoints included overall survival (OS) and occurrence of GVHD.

RESULTS

48 SCD patients underwent HSCT, 45 (93.8%) patients had MRD, 1 (2.1%) had 9/10 related donor, and 2 (4.1%) had MUD. The median age at transplant was 8.6 years (range, 3.1-13.8). Conditioning regimens were myeloablative (MAC) in 41 (85.4%) patients and of reduced intensity in 7 (14.6%) patients. EFS at 2 years was 100% among MAC group compared to 29% in the RIC group (p < .001). The median follow-up was 43.4 months (range 26.8-134). All events in the RIC group were secondary graft failure. However, OS was 100% in both groups at 2 years. Acute GVHD II-IV was diagnosed in 2 (4.1%) patients. Chronic GVHD occurred in 2 (4.1%) patients. GVHD did not occur in patients who underwent MUD HSCT.

CONCLUSIONS

MAC in children with SCD is well tolerated and associated with an excellent outcome for HLA-matched HSCT in SCD. There was a high rate of secondary graft failure with the use of RIC. Future studies are needed to optimize RIC regimens in HSCT of children with SCD.

Association between haploidentical hematopoietic stem cell transplantation combined with an umbilical cord blood unit and graft-versus-host disease in pediatric patients with acquired severe aplastic anemia

Background:

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) based on granulocyte colony-stimulating factor plus anti-thymocyte regimens (‘Beijing Protocol’) provides a salvage treatment for patients of acquired severe aplastic anemia (SAA) in China. However, graft-versus-host disease (GVHD) is a major impediment of haplo-HSCT due to human leukocyte antigen disparity. Recently, haplo-HSCT combined with umbilical cord blood (UCB) (haplo-cord HSCT) is performed in clinical trials to potentially reduce the risk of severe GVHD. Nevertheless, studies comparing GVHD in pediatric patients receiving haplo and haplo-cord HSCT for SAA are limited.

Objective:

The objective of this study was to investigate the impact of UCB co-infusion on GVHD in pediatric patients receiving haplo-HSCT for SAA.

Design:

We conducted a retrospective study of 91 consecutive SAA children undergoing haploidentical transplantation based on the ‘Beijing Protocol’ with or without co-infusion of UCB in our center.

Methods:

All patients received uniform non-myeloablative conditioning and GVHD prophylaxis. We compared baseline characteristics and transplant outcomes between the haplo (n = 35) and haplo-cord (n = 56) recipients.

Results:

All 91 patients achieved hematopoietic recovery from haploidentical donors, with a higher incidence of peri-engraftment syndrome observed with the haplo-cord group as compared with the haplo group (75.0% versus 48.6%, p = 0.029). Notably, the haplo-cord group showed a lower incidence of II–IV acute GVHD (aGVHD) than the haplo group (16.1% versus 42.9%, p = 0.002). Observed incidences of chronic GVHD (cGVHD) and moderate to severe cGVHD in the haplo-cord group were also lower than that in the haplo group (25.6% versus 51.3%, p = 0.019; 16.2% versus 41.3%, p = 0.016, respectively). Haplo-cord HSCT was identified as the only factor associated with a lower incidence of II–IV aGVHD and cGVHD in multivariate analysis. However, no differences were observed between the two groups for infections and survival outcomes.

Conclusion:

Our data indicated that co-infusion of UCB in ‘Beijing Protocol’-based haplo-HSCT may be effective for reducing the risk of severe GVHD in SAA children.

ADaPTS "(AD)olescents (P)ath through (T)ransplant (S)ickle cell disease"

Background

Sickle cell disease is an inherited chronic hematological disorder with an average lifespan of fifty years. The human cost of sickle cell disease includes missed school days, occupational opportunities, social isolation, stigmatization, and psychological sequelae. Hematopoietic cell transplantation (HCT) is the only curative therapy available but comes with potential morbidity and mortality. Our study explores how quality of life (QoL) is affected from the perspective of an adolescent who has undergone a nonmyeloablative matched sibling donor HCT.

Methods

We employed multiple case study methodology with purposeful sampling by selecting information-rich cases. Data sources: 1) QoL inventories 2) patient interviews 3) parent interview 4) vital support interview 5) medical record analysis. Data analysis: Intra-case analysis by assembling evidence within a single case and then analyzing the differences within cases to create a rich case description. Next, a time series analysis was completed to track changes in patients’ QoL. We used multiple sources of data to compose a timeline and changes across time. Then, we employed pattern matching as an analytical technique allowing for examination of patterns across cases. Finally, we used cross case synthesis to review results of each case.

Results

Quality of life was reported across the physical, social and psychological domains for 5 participants. All had sickle cell HgSS genotype, 80% were male and 80% were born outside of Canada. Physical domain: pre-transplant, 100% of patients experienced pain, and the majority suffered from fatigue, insomnia, and fevers resulting in hospitalizations. Afterwards, participants reported improved physical wellbeing. Social domain: pre-transplant, QoL was poor characterized by stigma, social isolation, and parental absenteeism. Post-HSCT adolescents gained social acceptance in areas that had stigmatized and excluded them. They were able to participate freely in activities with peers and their social life vastly improved. Psychological pre-transplant life experiences were overshadowed by psychological stress. The majority commented that their future was bleak and may lead to premature death. Afterwards adolescents described a crisis free life with positive psychological outcomes.

Conclusions

Adolescents with sickle cell disease who undertook HCT demonstrated improved QoL one year post transplant with regard to physical, social and psychological well-being.

Strategies for Success With Umbilical Cord Haematopoietic Stem Cell Transplantation in Children With Malignant and Non-Malignant Disease Indications

Umbilical Cord blood is an intuitively attractive stem cell source, but its use has declined since it is associated with an increased procedure-related morbidity and transplant related mortality. Some of this reflects that cord blood transplants are more often HLA-mismatched compared to other unrelated donor transplants. The ability to transplant in such a setting, indeed without high rates of chronic Graft versus Host Disease (GVHD), constitutes an advantage compared to other unrelated donor cell sources and there are other advantages specifically associated with cord blood as a donor cell source. These advantages must be weighed against its disadvantage, and we have utilised cord blood preferentially as a donor cell source in certain clinical situations in paediatric medicine. In non-malignant diseases, outcomes in metabolic disease are critically dependent on age at transplant and the enzyme delivered by that transplant, and in cord blood transplantation then the time to transplant can be minimised and the engrafted recipients have higher chimerism that delivers higher enzyme levels. In malignant diseases, studies have described reduced relapse rate and better GVHD-free survival, and so we have prioritised cord as a donor cell source where the risk of relapse is highest, and the effects of higher transplant related mortality is most clearly offset by the reduced relapse rates.

Significant improvement of child physical and emotional functioning after familial haploidentical stem cell transplant

Allogeneic stem cell transplantation (AlloSCT) represents the only curative therapy for sickle cell disease (SCD). However, limited availability of matched related donors and suboptimal outcomes following AlloSCT with unrelated donors has led to investigation of alternative donors. Among children with high-risk SCD, we evaluated health-related quality of life (HRQoL) impact in the two years following familial haploidentical SCT. HRQoL was collected from parent and child raters, using the Child Health Ratings Inventories Generic measure and haploidentical SCT-specific module. Repeated measures models were fit to assess HRQoL changes over time and by rater. Nineteen children (mean age 12.9 yrs [standard deviation, 5.3]; 63% male) and their parents were included. There were no differences in the 2-yr trajectories of child physical or emotional functioning (EF) by rater. Child physical functioning and EF scores were significantly lower at day +45 than baseline, but scores recovered by day +180. There was significant improvement in EF (p = 0.03) at 2 yrs vs baseline. A similar pattern of scores over time was seen for parent ratings of child's global HRQoL. Despite treatment intensity in the initial months following AlloSCT, patient scores recovered or exceeded baseline scores at two years. This trial is registered at clinicaltrials.gov (NCT01461837).

Hematopoietic Stem Cell Transplantation Stabilizes Cerebral Vasculopathy in High-Risk Pediatric Sickle Cell Disease Patients: Evidence From a Referral Transplant Center

BACKGROUND

Severe sickle cell disease (SCD) can present with different vaso-occlusive manifestations with cerebral vasculopathy (CV) as one of the most serious complications. Hematopoietic stem cell transplant (HSCT) is the ultimate therapy for this complication. The aim of this study was to assess the outcome and impact of HSCT on severe SCD patients with CV complications.

METHODS

Twenty-five consecutive transplants-naive pediatric SCD patients with CV complications underwent HSCT at our institution between 1993 and 2015, using bone marrow as stem cells source from fully match related donors were included. Neurologic evaluation was done both clinically and radiologically before transplantation and regularly following the HSCT.

RESULTS

With a median follow-up of 52.2 ± 5.8 months, the cumulative probability of overall survival (OS) at 3 years was 92.0% and event-free survival (EFS) was 88%. Significant neurologic improvements were observed in most of the patients clinically. Different neurologic complications were assessed. The neurologic manifestations before and after HSCT were hemiparesis (11, 1), seizures (13, 8), focal neurologic deficit (4, 2), loss of conscious (2, 1) headache (6, 1), and psychological symptoms (5, 2). Post-HSCT radiological imaging was done in 15 patients, which showed stabilization of CV among all.

CONCLUSIONS

Allogeneic HSCT in patients with severe SCD presenting with CV complications including moyamoya vasculopathy showed favorable outcome with significant clinical neurologic improvement and stabilization of the disease. None of the patients with severe vasculopathy underwent neurological vascular by-pass surgery prior to HSCT.

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.

Long-Term Effects of Allogeneic Hematopoietic Stem Cell Transplantation on Systemic Inflammation in Sickle Cell Disease Patients

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only currently available curative treatment for sickle cell disease (SCD). However, the effects of HSCT on SCD pathophysiology are poorly elucidated. Here, we assessed red blood cell (RBC) adhesiveness, intensity of hemolysis, vascular tone markers and systemic inflammation, in SCD patients treated with allogeneic HSCT. Thirty-two SCD patients were evaluated before and on long-term follow-up after HSCT. Overall survival was 94% with no severe (grade III-IV) graft-vs-host disease and a 22% rejection rate (graft failure). Hematological parameters, reticulocyte counts, and levels of lactate dehydrogenase (LDH), endothelin-1 and VCAM-1 normalized in SCD patients post-HSCT. Expression of adhesion molecules on reticulocytes and RBC was lower in patients with sustained engraftment. Levels of IL-18, IL-15 and LDH were higher in patients that developed graft failure. Increased levels of plasma pro-inflammatory cytokines, mainly TNF-α, were found in SCD patients long-term after transplantation. SCD patients with sustained engraftment after allo-HSCT showed decreased reticulocyte counts and adhesiveness, diminished hemolysis, and lower levels of vascular tonus markers. Nevertheless, systemic inflammation persists for at least five years after transplantation, indicating that allo-HSCT does not equally affect all aspects of SCD pathophysiology.

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.

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.

Treosulfan-induced myalgia in pediatric hematopoietic stem cell transplantation identified by an electronic health record text mining tool

Treosulfan is increasingly used as myeloablative agent in conditioning regimen prior to allogeneic hematopoietic stem cell transplantation (HSCT). In our pediatric HSCT program, myalgia was regularly observed after treosulfan-based conditioning, which is a relatively unknown side effect. Using a natural language processing and text-mining tool (CDC), we investigated whether treosulfan compared with busulfan was associated with an increased risk of myalgia. Furthermore, among treosulfan users, we studied the characteristics of given treatment of myalgia, and studied prognostic factors for developing myalgia during treosulfan use. Electronic Health Records (EHRs) until 28 days after HSCT were screened using the CDC for myalgia and 22 synonyms. Time to myalgia, location of pain, duration, severity and drug treatment were collected. Pain severity was classified according to the WHO pain relief ladder. Logistic regression was performed to assess prognostic factors. 114 patients received treosulfan and 92 busulfan. Myalgia was reported in 37 patients; 34 patients in the treosulfan group and 3 patients in the busulfan group (p = 0.01). In the treosulfan group, median time to myalgia was 7 days (0–12) and median duration of pain was 19 days (4–73). 44% of patients needed strong acting opiates and adjuvant medicines (e.g. ketamine). Hemoglobinopathy was a significant risk factor, as compared to other underlying diseases (OR 7.16 95% CI 2.09–30.03, p = 0.003). Myalgia appears to be a common adverse effect of treosulfan in pediatric HSCT, especially in hemoglobinopathy. Using the CDC, EHRs were easily screened to detect this previously unknown side effect, proving the effectiveness of the tool. Recognition of treosulfan-induced myalgia is important for adequate pain management strategies and thereby for improving the quality of hospital stay.

Stable to improved cardiac and pulmonary function in children with high-risk sickle cell disease following haploidentical stem cell transplantation

Children with sickle cell disease (SCD) are at high-risk of progressive, chronic pulmonary and cardiac dysfunction. In this prospective multicenter Phase II trial of myeloimmunoablative conditioning followed by haploidentical stem cell transplantation in children with high-risk SCD, 19 patients, 2.0-21.0 years of age, were enrolled with one or more of the following: history of (1) overt stroke; (2) silent stroke; (3) elevated transcranial Doppler velocity; (4) multiple vaso-occlusive crises; and/or (5) two or more acute chest syndromes and received haploidentical transplants from 18 parental donors. Cardiac and pulmonary centralized cores were established. Pulmonary function results were expressed as percent of the median of healthy reference cohorts, matched for age, sex, height and race. At 2 years, pulmonary functions including forced expiratory volume (FEV), FEV₁/ forced vital capacity (FVC), total lung capacity (TLC), diffusing capacity of lung for carbon monoxide (DLCO) were stable to improved compared to baseline values. Importantly, specific airway conductance was significantly improved at 2 years (p < 0.004). Left ventricular systolic function (fractional shortening) and tricuspid regurgitant velocity were stable at 2 years. These results demonstrate that haploidentical stem cell transplantation can stabilize or improve cardiopulmonary function in patients with SCD.

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

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

Development of β-globin gene correction in human hematopoietic stem cells as a potential durable treatment for sickle cell disease

Sickle cell disease (SCD) is the most common serious monogenic disease with 300,000 births annually worldwide. SCD is an autosomal recessive disease resulting from a single point mutation in codon six of the β-globin gene (HBB). Ex vivo β-globin gene correction in autologous patient-derived hematopoietic stem and progenitor cells (HSPCs) may potentially provide a curative treatment for SCD. We previously developed a CRISPR-Cas9 gene targeting strategy that uses high-fidelity Cas9 precomplexed with chemically modified guide RNAs to induce recombinant adeno-associated virus serotype 6 (rAAV6)-mediated HBB gene correction of the SCD-causing mutation in HSPCs. Here, we demonstrate the preclinical feasibility, efficacy, and toxicology of HBB gene correction in plerixafor-mobilized CD34⁺ cells from healthy and SCD patient donors (gcHBB-SCD). We achieved up to 60% HBB allelic correction in clinical-scale gcHBB-SCD manufacturing. After transplant into immunodeficient NSG mice, 20% gene correction was achieved with multilineage engraftment. The long-term safety, tumorigenicity, and toxicology study demonstrated no evidence of abnormal hematopoiesis, genotoxicity, or tumorigenicity from the engrafted gcHBB-SCD drug product. Together, these preclinical data support the safety, efficacy, and reproducibility of this gene correction strategy for initiation of a phase 1/2 clinical trial in patients with SCD.

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.

Hematopoietic stem cell transplantation for people with β-thalassaemia

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Intrabone infusion for allogeneic umbilical cord blood transplantation in children

Umbilical cord blood transplantation (UCBT) has been used to treat malignant and non-malignant diseases. UCBT offers the advantages of easy procurement and acceptable partial HLA mismatches, but also shows delayed hematopoietic and immunological recoveries. We postulated that an intrabone (IB) infusion of cord blood could provide a faster short- and long-term engraftment in a pediatric population with malignant and non-malignant hematologic diseases. We conducted this phase I-II single arm, exploratory clinical trial (NCT01711788) from 2012 to 2016 in a single center. Fifteen patients aged from 1.9 to 16.4 years received an IB UCBT. Median time to neutrophils and platelet recoveries were 18 days (range: 13-36 days) and 42 days (range: 26-107 days), respectively. Rate of severe acute GVH grade was low, with only one patient with grade III aGVH. Relapse occurred in 5 patients (38.5%) and TRM occurred in 1 patient. This leads to 6 years EFS and OS of 66.7% and 80% respectively. In conclusion, IB UCBT is safe and well-tolerated in children and hematological recovery compared similarly to the results obtained with IV UCBT.

Allogeneic hematopoietic stem cell transplantation from sibling and unrelated donors in pediatric patients with sickle cell disease-A single center experience

HSCT is curative in SCD. Patients with HLA-identical sibling donor have an excellent outcome ranging from 90%-100% overall and event-free survival. However, due to the lack of matched sibling donors this option is out of reach for 70% of patients with SCD. The pool of potential donors needs to be extended. Transplantations from HLA-matched unrelated donors were reported to be less successful with shorter event-free survival and higher incidences of complications including graft-vs-host disease, especially in patients with advanced stage SCD. Here we report transplantation outcomes for 25 children with SCD transplanted using HLA-matched grafts from related or unrelated donors. Overall survival was 100% with no severe (grade III-IV) graft-vs-host disease and a 12% rejection rate. Mixed donor chimerisms only occurred in transplantations from siblings, while transplantations from unrelated donors resulted in either complete donor chimerism or rejection. Despite the small patient number, overall and disease-free survival for unrelated donor transplantations is excellent in this cohort. The advanced disease state, higher alloreactive effect and stronger immunosuppression in unrelated donor transplantations raises patient risk, for which possible solutions could be found in optimization of transplant preparation, graft manipulation or haploidentical transplantation using T cell receptor α/β-depleted grafts.

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.

Gene Therapy of the Hemoglobinopathies

Sickle cell disease and the ß-thalassemias are caused by mutations of the ß-globin gene and represent the most frequent single gene disorders worldwide. Even in European countries with a previous low frequency of these conditions the prevalence has substantially increased following large scale migration from Africa and the Middle East to Europe. The hemoglobin diseases severely limit both, life expectancy and quality of life and require either life-long supportive therapy if cure cannot be achieved by allogeneic stem cell transplantation. Strategies for ex vivo gene therapy aiming at either re-establishing normal ß-globin chain synthesis or at re-activating fetal γ-globin chain and HbF expression are currently in clinical development. The European Medicine Agency (EMA) conditionally licensed gene addition therapy based on lentiviral transduction of hematopoietic stem cells in 2019 for a selected group of patients with transfusion dependent non-ß° thalassemia major without a suitable stem cell donor. Gene therapy thus offers a relevant chance to this group of patients for whom cure has previously not been on the horizon. In this review, we discuss the potential and the challenges of gene addition and gene editing strategies for the hemoglobin diseases.

Gene therapies for transfusion dependent β-thalassemia: Current status and critical criteria for success

Thalassemia is one of the most prevalent monogenic diseases usually caused by quantitative defects in the production of β-globin leading to severe anemia. Technological advances in genome sequencing, stem cell selection, viral vector development, transduction and gene editing strategies now allow for efficient exvivo genetic manipulation of human stem cells that can lead to production of hemoglobin, leading to a meaningful clinical benefit in thalassemia patients. In this review, the status of the gene-therapy approaches available for transfusion dependent thalassemia are discussed, along with the critical criteria that affect efficacy and lessons that have been learned from the early phase clinical trials. Salient steps necessary for the clinical development, manufacturing, and regulatory approvals of gene therapies for thalassemia are also highlighted, so that the potential of these therapies can be realized. It is highly anticipated that gene therapies will soon become a treatment option for patients lacking compatible donors for hematopoietic stem cell transplant and will offer an alternative for definitive treatment of β-thalassemia.