Unrelated donor cord blood transplantation for children with severe sickle cell disease: results of one cohort from the phase II study from the Blood and Marrow Transplant Clinical Trials Network (BMT CTN)

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.

Hematopoietic stem cell transplantation for B-thalassemia major with alemtuzumab

While matched related donor (MRD) allogeneic hematopoietic stem cell transplantation (HSCT) is a curative option for transfusion-dependent beta-thalassemia (TDT), the use of alternative sources has increased, resulting in the exploration of novel transplant-conditioning regimens to reduce the contribution of graft-versus-host disease (GVHD) and graft failure (GF) to transplant-related morbidity and mortality. Alemtuzumab is a CD52 monoclonal antibody that has been successfully incorporated into myeloablative conditioning regimens for other hematologic conditions, yet there have been limited studies regarding the use of alemtuzumab in HSCT for TDT. The purpose of this study was to evaluate engraftment, incidence of GVHD, and transplant related morbidity and mortality in patients with TDT who received alemtuzumab in addition to standard busulfan-based conditioning. The primary endpoint was severe GVHD-free, event-free survival (GEFS). Our cohort included 24 patients with a median age of 6.8 years (range 1.5-14.9). Eleven patients received a 10/10 MRD HSCT, eleven 10/10 unrelated donor (UD), and two mismatched UD. All patients achieved primary engraftment. For all patients, 5-year GEFS was 77.4% and 5-year overall survival (OS) was 91%. The 5-year cumulative incidence of GF (attributed to poor graft function) without loss of donor chimerism was 13.8% (95% CI: 4.5, 35.3). We report low rates of significant acute GVHD grade II-IV (12.5%) and chronic GVHD (4.4%). Younger age and MRD were associated with significantly improved GEFS, OS and EFS. Our results show that the use of alemtuzumab promotes stable engraftment, may reduce rates of severe GVHD, and results in acceptable GEFS, OS, and EFS.

A systematic review comparing allogeneic hematopoietic stem cell transplant to gene therapy in sickle cell disease

INTRODUCTION

Allogeneic hematopoietic stem cell transplant (HSCT) and gene therapy (GT) are two potentially curative approaches for sickle cell disease (SCD), but they have never been compared in clinical trials.

OBJECTIVE

To compare the safety and efficacy of HSCT and GT to assist clinicians and patients in making informed treatment decisions.

METHODS

Phase I-III clinical trials and case reports/series were included. Regimens included HSCT from all stem cell sources, lentiviral gene therapy, and gene editing, with any conditioning regimen. We searched Medline and EMBASE databases as of 1st June 2020 for studies reporting HSCT and GT outcomes in SCD. The Newcastle-Ottawa scale was used to assess the risk of bias. Descriptive statistics and post-hoc imputation for standard deviations of mean change in FEV1 and FVC were performed.

RESULTS

In total, 56 studies (HSCT, n = 53; GT, n = 3) representing 1,198 patients met inclusion criteria (HSCT, n = 1,158; GT, n = 40). Length of follow-up was 3,881.5 and 58.7 patient-years for HSCT and GT, respectively. Overall quality of evidence was low, with no randomized controlled trials identified. Two-year overall survival for HSCT was 91%; mortality was 2.5% for GT. Acute chest syndrome and vaso-occlusive episodes were reduced post-HSCT and GT. Meta-analysis was not possible due to lack of comparator and heterogeneity in outcome measures reporting. Very few studies reported post-transplant end-organ function. Six secondary malignancies (5 post-HSCT, 1 post-GT) were reported.

DISCUSSION

Reporting of SCD-related complications and patient-important outcomes is lacking for both strategies. We advocate for standardized reporting to better compare outcomes within and between treatment groups.

Mixed donor chimerism following stem cell transplantation for sickle cell disease

Sickle cell disease is a debilitating hemoglobinopathy with high morbidity and mortality. Hematopoietic stem cell transplantation (HCT) is curative, but the presence of mixed donor/recipient chimerism post-HCT raises concerns about disease control long-term. Mixed donor/recipient chimerism is reported in significant numbers even after aggressive HCT conditioning regimens. Post-HCT, adequacy of donor erythropoiesis is crucial for disease control. This review explores the relationship between mixed donor/recipient chimerism and outcomes post-HCT. Serial chimerism analysis in lineage specific manner in erythroid or myeloid cells post-HCT predicts for disease control and HCT success. Adequate and stable donor-derived erythropoiesis is essential for reversing SCD manifestations. Myeloid lineage chimerism mirrors erythropoiesis is commercially available, and a reliable indicator of adequacy. Using this tool, the minimum threshold of donor chimerism is required to prevent SCD-related complications and maintain sickle hemoglobin less than 50% is approximately 20-25% even when a donor has Hb S trait. Curative interventions should, at a minimum, meet this goal long-term. Achieving a balance between successful engraftment while minimizing toxicity is important in patients vulnerable because of age or preexisting morbidity and is the objective of recent clinical trials. As HCT and gene therapies evolve, efficient long-term follow-up that includes durability assessment of mixed donor/recipient chimerism will be crucial.

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.

Sickle cell disease and acute leukemia: one case report and an extensive review

Population-based studies and case reports suggest that there may be an increased risk of acute leukemia associated with sickle cell disease (SCD). Following the description of a new case report, an extensive review of the literature identified 51 previously described cases. Most cases study showed myelodysplastic features confirmed, when available, by genetic markers such as chromosome 5 and/or chromosome 7 abnormalities and TP53 gene mutations. The increased risk of leukemogenesis is certainly multifactorial and related to the pathophysiologic mechanisms of the clinical manifestations of SCD. Chronic hemolysis and secondary hemochromatosis may cause increased chronic inflammation, resulting in persistent marrow stress, which could potentially compromise the genomic stability of the hematopoietic stem cells generating genomic damage and somatic mutations over the course of SCD and its treatment, resulting in a clone that led to acute myeloid leukemia.

Diverse Approaches to Gene Therapy of Sickle Cell Disease

Sickle cell disease (SCD) results from a single base pair change in the sixth codon of the β-globin chain of hemoglobin, which promotes aggregation of deoxyhemoglobin, increasing rigidity of red blood cells and causing vaso-occlusive and hemolytic complications. Allogeneic transplant of hematopoietic stem cells (HSCs) can eliminate SCD manifestations but is limited by absence of well-matched donors and immune complications. Gene therapy with transplantation of autologous HSCs that are gene-modified may provide similar benefits without the immune complications. Much progress has been made, and patients are realizing significant clinical improvements in multiple trials using different approaches with lentiviral vector-mediated gene addition to inhibit hemoglobin aggregation. Gene editing approaches are under development to provide additional therapeutic opportunities. Gene therapy for SCD has advanced from an attractive concept to clinical reality.

Across the Myeloablative Spectrum: Hematopoietic Cell Transplant Conditioning Regimens for Pediatric Patients with Sickle Cell Disease

One out of every five hundred African American children in the United States has sickle cell disease (SCD). While multiple disease-modifying therapies are available, hematopoietic cell transplantation (HCT) remains the only curative option for children with SCD. HLA-matched sibling HCT has demonstrated excellent efficacy, but its availability remains limited; alternative donor strategies are increasingly explored. While Busulfan-Cyclophosphamide has become the most widespread conditioning regimen employed in HCT for pediatric SCD, many other regimens have been examined. This review explores different conditioning regimens across the intensity spectrum: from myeloablative to non-myeloablative. We describe survival and organ function outcomes in pediatric SCD patients who have received HCT and discuss the strengths and weaknesses of the various conditioning intensities. Finally, we posit novel directions in allogeneic HCT for SCD.

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 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.

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.

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.

Allogeneic hematopoietic stem cell transplant for sickle cell disease: The why, who, and what

Allogeneic hematopoietic stem cell transplants (allo-HSCTs) from matched-related donors (MRDs), mismatched-related donors (MMRDs), and matched-unrelated donors (MUDs) are increasingly being used to treat sickle cell disease (SCD) in both pediatric and adult patients. The overall results have been extremely encouraging, especially if a MRD is available and the transplant being performed before the age of 13. Although there is a general consensus that patients with high-risk SCD, even in adults and irrespective of donor characteristics, should be offered allo-HSCT, the debates on optimal patient selection and timing of transplant have yet to be resolved. Unlike patients with hematologic malignancies, there are also a number of clinical issues that require to be addressed in patients with SCD undergoing allo-HSCT. In this review, we will discuss the reasons allo-HSCT should be offered more widely to patients with SCD, the challenges facing physicians in patient selection and timing of transplant, and the awareness of and solutions to prevent the complications that are unique or more common in SCD undergoing allo-HSCT.

Gene Therapy for Sickle Cell Disease - Moving from the Bench to the Bedside

Gene therapy as a potential cure for sickle cell disease (SCD) has long been pursued given that this hemoglobin disorder results from a single point mutation. Advances in genomic sequencing, increased understanding of hemoglobin regulation and discoveries of molecular tools for genome modification of hematopoietic stem cells have made gene therapy for SCD possible. Gene addition strategies using gene transfer vectors have been optimized over the last few decades to enable expression of normal or anti-sickling globins as strategies to ameliorate SCD. Many hurdles had to be addressed prior to clinical translation including collection of sufficient stem cells for gene-modification, increasing expression of transferred genes to a therapeutic level and conditioning patients in a safe manner that enabled adequate engraftment of gene-modified cells. The discovery of genome editors that make precise modifications has further advanced the safety and efficacy of gene therapy and a rapid movement to clinical trial has undoubtedly been supported by lessons learned from optimizing gene addition strategies. Current gene therapies being tested in clinical trial require significant infrastructure and expertise given the needs to harvest cells from and administer chemotherapy to patients who often have significant organ dysfunction and that gene-modification takes place ex vivo in specialized facilities. For these therapies to realize their full potential they would need to be portable, safe and efficient making an in-vivo based approach attractive. Additionally, adequate resources for SCD screening and access to standardized care are critically important for gene therapy to be a viable treatment option for SCD.

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.

Pretransplant myeloid and immune suppression, reduced toxicity conditioning with posttransplant cyclophosphamide: Initial outcomes of novel approach for matched unrelated donor hematopoietic stem cell transplant for hemoglobinopathies

Hematopoietic stem cell transplant (HSCT) is currently the only curative option for thalassemia major (TM) and sickle cell disease (SCD). We report our experience of using pretransplant immune suppression (PTIS), augmented Johns Hopkins conditioning, and posttransplant cyclophosphamide (PTCy) as graft-versus-host disease (GvHD) prophylaxis for matched unrelated donor (MUD) transplant in TM/SCD. At a median follow-up of 307.5 days (range 251-395), all patients (three TM, one SCD) are alive and disease free. MUD HSCT with PTIS, augmented Johns Hopkins conditioning, and PTCy as GvHD prophylaxis is a promising way of treating patients with hemoglobinopathies with low regimen-related toxicity (RRT), no risk of graft failure (GF) and minimal GvHD rates.

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.

Parameters affecting successful stem cell collections for genetic therapies in sickle cell disease

Emerging cellular therapies require the collection of peripheral blood hematopoietic stem cells (HSC) by apheresis for in vitro manipulation to accomplish gene addition or gene editing. These therapies require relatively large numbers of HSCs within a short time frame to generate an efficacious therapeutic product. This review focuses on the principal factors that affect collection outcomes, especially relevant to gene therapy for sickle cell disease.

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.

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.

Clinical outcomes following bone marrow transplantation in patients with sickle cell disease: A cohort study of US Medicaid enrollees

OBJECTIVES

Bone marrow transplantation (BMT) is currently the only curative therapy available for patients with sickle cell disease (SCD), but clinical outcomes in routine care are not well understood. We describe the rates of vaso-occlusive crises (VOCs), transplant complications, and mortality in SCD patients after BMT.

METHODS

A cohort study of SCD patients who underwent BMT was designed using US Medicaid claims data (2000-2013).

RESULTS

A total of 204 SCD patients undergoing BMT were identified with a mean (SD) age of 10.6 (7.3) years, with 52.9% male and 67.6% African American. The overall VOC rate was 0.99 per person-year (95% CI: 0.91-1.07) over a median follow-up time of 2.1 years (IQR: 0.8-4.3 years). A total of 138 (67.6%) remained free of VOCs. The mortality rate was 1.7 (95% CI: 0.9-3.1) per 100 person-years, transplant-related complications occurred among 113 (55.4%) patients with an incidence rate of 38.2 (95% CI: 31.7-45.9) per 100 person-years, while 47 (23%) patients had GvHD with an incidence rate of 8.0 (95% CI: 6.0-10.7) per 100 person-years.

CONCLUSION

Two thirds of the BMT recipients remained VOC-free over 2 years of follow-up, but transplant-related complications, including GvHD occurred with high frequency. This highlights a continuing unmet need for alternative curative interventions in SCD.

Timing of Alemtuzumab With Respect to Day of Bone Marrow Infusion and its Effects Upon Engraftment and Graft-Versus-Host Disease in Patients With Sickle Cell Disease: A Single-Institutional Study

The possible impact of "late" alemtuzumab (administered on days -10 to -8) versus "early" alemtuzumab (-19 to -17) with respect to engraftment and acute/chronic graft-versus-host disease (GvHD) in a group of 25 pediatric patients with sickle cell disease undergoing bone marrow transplantation following conditioning with alemtuzumab, fludarabine, and melphalan is reported. The first 9 patients received "late" alemtuzumab followed by bone marrow transplantation from HLA-matched sibling donors. The next 16 patients undergoing matched sibling transplants received "early" alemtuzumab. In the "late" group, 1 patient (11%) developed acute GvHD. Six patients (67%) achieved sustained engraftment. Three patients (33%) experienced graft rejection, leading to termination of enrollment of patients on this regimen. In the "early" alemtuzumab group, acute and chronic GvHD developed in 43% and 25% patients, respectively. None of the patients experienced graft rejection in this group of patients. Three patients developed stable mixed chimerism and 13 patients demonstrated 100% donor chimerism at 1 year post-transplant and beyond. These results suggest a benefit with respect to engraftment of administering "early" versus "late" alemtuzumab in this reduced-intensity conditioning regimen, however, with the possible cost of an increase in acute, and possibly chronic GvHD.

[Allogeneic hematopoietic stem cell transplant in children and adults with sickle cell disease: Indications and modalities]

Sickle cell disease is associated with severe complications and early mortality in adults. In children, hematopoietic stem cell transplant from HLA-identical sibling can stop the progression of the disease and leads to more than 95% long-term free survival without sickle cell disease. The aim of this workshop was to define indications and modalities of allogeneic hematopoietic stem cell transplant in children and adults with sickle cell disease. Patient and sibling HLA typing should be proposed, early in the course of the disease, when intensification therapies are required. Indications of transplant from HLA-identical sibling in children and adults are, cerebral vasculopathy, occurrence of vaso-occlusive events despite hydroxycarbamide, renal and hepatic diseases related to SCD, chronic anemia<7g/dL despite hydroxycarbamide, need to maintain transfusion programs longer than six months, and major transfusion difficulties related to red blood cell alloimmunization. In children with an HLA-identical sibling donor, we recommend a myeloablative conditioning regimen associating high dose busulfan, cyclophosphamide and ATG, considering the excellent results of this approach In patients over 15 years of age, we recommend the NIH approach consisting of a reduced intensity conditioning regimen by alemtuzumab, and 3Gy total body irradiation, followed by peripheral hematopoietic stem cells and post-transplant immunosuppression by sirolimus In the absence of HLA-identical sibling donor, there is no definitive data for preferring transplant from unrelated versus haplo-identical donors but we recommend to evaluate these approaches in prospective trials.

Stable renal function in children and adolescents with sickle cell disease after nonmyeloablative hematopoietic stem cell transplantation

BACKGROUND

Sickle cell disease (SCD) is associated with renal complications starting as early as infancy. Allogeneic hematopoietic stem cell transplant (HSCT) treatments using newer nonmyeloablative (NMA) conditioning regimens show promising results in treating SCD in the pediatric population, but renal outcome parameters after transplantation have not been described.

AIM

To describe baseline renal parameters as well as short- and long-term renal outcomes in pediatric patients with SCD who underwent NMA-HSCT.

METHODS

A retrospective chart review of pediatric patients who received NMA-HSCT in Alberta, Canada. Short-term renal outcomes evaluated were: (1) acute kidney injury (AKI), (2) fluid overload (FO), and (3) hypertension. Long-term outcomes evaluated were: (1) estimated glomerular filtration rate (eGFR) development and at last follow-up with hyperfiltration defined as eGFR ≥ 150 mL/min/1.73 m² , (2) proteinuria, and (3) hypertension.

RESULTS

The mean follow-up time was 128.6 weeks (standard deviations, 69.3). No posttransplant AKI events or FO were observed. eGFR remained > 90 mL/min/1.73 m² at last follow-up in all patients, whereas hyperfiltration was present in eight (44.4%) and four (22.2%) patients pre- and post-HSCT, respectively, which are significantly different (P < 0.0001). Consequently, median GFR was significantly higher pre-HSCT compared with 24 months HSCT (P < 0.009). Long-term hypertension post-HSCT was present in six patients (33.3%).

CONCLUSION

This study describes stable kidney function in children with SCD after NMA-HSCT without evidence of AKI or FO episodes. Rates of hyperfiltration decreased post-HSCT, which signifies that NMA-HSCT could potentially preserve long-term renal function in this population at risk of progressive chronic kidney disease. Further prospective studies are needed to confirm these novel findings.

Hematopoietic stem cell transplantation and cellular therapy in sickle cell disease: where are we now?

PURPOSE OF REVIEW

Sickle cell disease (SCD) is a common monogenic disorder that is characterized by an A to T substitution in the β-globin gene that leads to the production of hemoglobin S (HbS). Polymerization of HbS leads to significant morbidity including vaso-occlusion, pain, hemolytic anemia, and end organ damage. Allogeneic hematopoietic cell transplantation (allo-HCT) is the only curative treatment; however, suitable donors are not always readily available. This study reviews the current status of allo-HCT and autologous cellular therapies for SCD.

RECENT FINDINGS

Alternative sources of allogeneic stem cells from unmatched donors such as cord blood and haploidentical donors are gaining traction. Early experience has shown that better conditioning regimens and graft-versus-host disease prophylaxis are needed before these donor sources can gain widespread use. Clinical trials are underway to determine the feasibility and efficacy of autologous transplantation with gene modified hematopoietic stem cells. Gene therapy strategies include HbS gene correction, gene addition, and hemoglobin F induction. Preliminary results are very encouraging.

SUMMARY

Matched sibling allo-HCT for patients with SCD results in more than 90% overall survival and more than 80% event-free survival. Because only 25-30% of patients have a matched sibling donor, alternative donor options such as matched unrelated donors, related haploidentical donors and unrelated umbilical cord blood donors are being considered. Clinical trials investigating various strategies for gene therapy followed by autologous transplantation are underway. One major challenge is obtaining sufficient hematopoietic stem cells for gene therapy. Studies are being conducted on the optimal mobilization regimen and collection strategy.

Recent Advances in the Treatment of Sickle Cell Disease

Sickle cell anemia (SCA) was first described in the Western literature more than 100 years ago. Elucidation of its molecular basis prompted numerous biochemical and genetic studies that have contributed to a better understanding of its pathophysiology. Unfortunately, the translation of such knowledge into developing treatments has been disproportionately slow and elusive. In the last 10 years, discovery of BCL11A, a major γ-globin gene repressor, has led to a better understanding of the switch from fetal to adult hemoglobin and a resurgence of efforts on exploring pharmacological and genetic/genomic approaches for reactivating fetal hemoglobin as possible therapeutic options. Alongside therapeutic reactivation of fetal hemoglobin, further understanding of stem cell transplantation and mixed chimerism as well as gene editing, and genomics have yielded very encouraging outcomes. Other advances have contributed to the FDA approval of three new medications in 2017 and 2019 for management of sickle cell disease, with several other drugs currently under development. In this review, we will focus on the most important advances in the last decade.

What is the place of hematopoietic stem cell transplantation in the management of cerebral vasculopathy in children with sickle cell anemia?

Cerebral vasculopathy is the most severe complication affecting children with sickle cell anemia. Significant progress has been made in the management of sickle cell anemia cerebral vasculopathy, including early transcranial Doppler screening, chronic transfusion, andhydroxyurea. Nevertheless, for patients with a potential matched-sibling donor (MSD), stem cell transplantation (SCT) is now the treatment offering the best cerebral vasculopathy outcome. In the absence of MSD,alternative SCT should be recommended only in those with worsening cerebral vasculopathy despite standard treatments, and should be limited to related haplo-identical SCT undertaken in controlled studies.

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.

Emerging therapies in sickle cell disease

Despite sickle cell disease (SCD) being the most common and severe inherited condition worldwide, therapeutic options are limited. To date, hydroxyurea remains the main treatment option in SCD. However, in the last decade the numbers of interventional clinical trials focussing on therapies for SCD have increased significantly. Many new drugs with various pharmacological targets have emerged and, although the majority have failed to show benefit in clinical trials, some have produced encouraging results. It seems probable that more drugs will soon become available for the treatment of SCD. Furthermore, promising clinical trials with improved outcomes have recently changed the perspective of curative therapies in SCD. Nevertheless, the application of novel therapeutic agents and potential curative treatments will most likely be limited to high-income countries and, thus, will remain unavailable for the majority of people with SCD in the foreseeable future.

Curative options for sickle cell disease: haploidentical stem cell transplantation or gene therapy?

Haematopoietic stem cell transplantation (HSCT) is curative in sickle cell disease (SCD); however, the lack of available matched donors makes this therapy out of reach for the majority of patients with SCD. Alternative donor sources such as haploidentical HSCT expand the donor pool to nearly all patients with SCD, with recent data showing high overall survival, limited toxicities, and effective reduction in acute and chronic graft-versus-host disease (GVHD). Simultaneously, multiple gene therapy strategies are entering clinical trials with preliminary data showing their success, theoretically offering all patients yet another curative strategy without the morbidity and mortality of GVHD. As improvements are made for alternative donors in the allogeneic setting and as data emerge from gene therapy trials, the optimal curative strategy for any individual patient with SCD will be determined by many critical factors including efficacy, transplant morbidity and mortality, safety, patient disease status and preference, cost and applicability. Haploidentical may be the preferred choice now based mostly on availability of data; however, gene therapy is closing the gap and may ultimately prove to be the better option. Progress in both strategies, however, makes cure more attainable for the individual with SCD.

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.

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.

Why, Who, When, and How? Rationale for Considering Allogeneic Stem Cell Transplantation in Children with Sickle Cell Disease

Considering the progress made in the management of sickle cell disease during the past 30 years, along with the excellent results obtained with hematopoietic stem cell transplantation (SCT), it is important to reexamine why, who, when and how to recommend allogeneic SCT in children with sickle cell disease. While sickle cell disease has a low risk of death in children and a high risk for morbidity during aging, SCT carries an early risk of death, graft-vs-host disease and infertility. Nevertheless, SCT offers at least 95% chance of cure with low risk of chronic graft-vs-host disease when a matched-sibling donor is available and the risks of infertility can be reduced by ovarian, sperm or testis cryopreservation. Thus, all available therapies such as hydroxyurea, transfusions and SCT should be presented to the parents, providers, and affected children and discussed with them from infancy. Furthermore, the use of these therapies should be adjusted to the severity of the disease and to local availabilities in order to choose the treatment offering the best benefit/risk ratio.

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.

Characterization of natural killer cells expressing markers associated with maturity and cytotoxicity in children and young adults with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is increasingly recognized as a red blood cell disorder modulated by abnormally increased inflammation. We have previously shown that in patients with SCD not on a disease-modifying therapy (hydroxyurea or chronic transfusions), natural killer (NK) cell numbers are increased. In the current study, we further investigated the NK cell function to determine if there was evidence of increased activation and cytotoxicity.

PROCEDURE

We conducted a cross-sectional study of 44 patients with HbSS/HbSβ⁰ thalassemia at steady state (hydroxyurea = 13, chronic transfusion = 11, no disease-modifying therapy = 20) and 23 healthy controls. Using a fresh blood sample, NK immunophenotyping was performed as follows: NK cells (CD3^- CD56⁺ lymphocytes) were evaluated for makers associated with activation (NKG2D, NKp30, NKp44, and CD69) and maturity (CD57, killer immunoglobulin-like receptors (KIR), and CD56dim). Degranulation and cytotoxicity assays were performed to evaluate NK cell function.

RESULTS

Patients with SCD who were not on disease-modifying therapy had a higher number of NK cells with an immunophenotype associated with increased cytotoxicity (NKG2D⁺ , NKp30⁺ , CD56dim⁺ , and KIR⁺ NK cells) compared with healthy controls and patients on hydroxyurea. NK cells from SCD patients not on disease-modifying therapy demonstrated significantly increased cytotoxicity (measured by assaying NK cell killing of the K562 cell line) compared with healthy controls (P = 0.005). Notably, NK cell cytotoxicity against K562 cells in the hydroxyurea or chronic transfusion patients was not significantly different from that in healthy controls.

CONCLUSION

SCD is associated with increased NK cell function as well as increased NK cell numbers, which appears to be normalized with disease-modifying therapy.

Indications for haematopoietic stem cell transplantation for haematological diseases, solid tumours and immune disorders: current practice in Europe, 2019

This is the seventh special EBMT report on the indications for haematopoietic stem cell transplantation for haematological diseases, solid tumours and immune disorders. Our aim is to provide general guidance on transplant indications according to prevailing clinical practice in EBMT countries and centres. In order to inform patient decisions, these recommendations must be considered together with the risk of the disease, the risk of the transplant procedure and the results of non-transplant strategies. In over two decades since the first report, the EBMT indications manuscripts have incorporated changes in transplant practice coming from scientific and technical developments in the field. In this same period, the establishment of JACIE accreditation has promoted high quality and led to improved outcomes of patient and donor care and laboratory performance in transplantation and cellular therapy. An updated report with operating definitions, revised indications and an additional set of data with overall survival at 1 year and non-relapse mortality at day 100 after transplant in the commonest standard-of-care indications is presented. Additional efforts are currently underway to enable EBMT member centres to benchmark their risk-adapted outcomes as part of the Registry upgrade Project 2020 against national and/or international outcome data.

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

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