Effect of myeloablative bone marrow transplantation on growth in children with sickle cell anaemia: results of the multicenter study of haematopoietic cell transplantation for sickle cell anaemia

The Effects of Treatment with Blood Transfusion, Iron Chelation and Hydroxyurea on Puberty, Growth and Spermatogenesis in Sickle Cell Disease (SCD): A short update

Sickle cell disease (SCD) is traditionally associated with growth failure and delayed puberty. Wasting and stunting are still prevalent in children and adolescents with SCD, especially in developing countries. In addition, sperm abnormalities are frequent in males with SCD, with high rates of low sperm density, low sperm counts, poor motility, and increased abnormal morphology. Severe anaemia, vaso-occlusive attacks with ischemic injury to different organs including the pituitary gland and testis, and nutritional factors are incriminated in the pathogenesis of defective growth, puberty, and spermatogenesis. There is great phenotypic variability among patients with SCD. The variability in the clinical severity of SCD can partly be explained by genetic modifiers, including HbF level and co-inheritance of α-thalassaemia. In the past, severe disease led to early mortality. Advancements in treatment have allowed patients with SCD to have a longer and better quality of life. For most patients, the mainstays of treatment are preventive and supportive. For those with severe SCD, three major therapeutic options are currently available: erythrocyte transfusion or exchange, hydroxyurea and hematopoietic stem cell transplantation. In this mini review the authors tried to recognize, delineate, and update knowledge on abnormalities due to SCD from those created by the use of different treatment modalities. (www.actabiomedica.it)

Current Results and Future Research Priorities in Late Effects after Hematopoietic Stem Cell Transplantation for Children with Sickle Cell Disease and Thalassemia: A Consensus Statement from the Second Pediatric Blood and Marrow Transplant Consortium International Conference on Late Effects after Pediatric Hematopoietic Stem Cell Transplantation

Sustained donor engraftment after allogeneic hematopoietic cell transplantation (HCT) converts to healthy donor hemoglobin synthesis and halts disease symptoms in patients with sickle cell disease and thalassemia major. A disease-free survival probability that exceeds 90% has been reported when HCT using an HLA-matched sibling donor is performed in young patients with low-risk disease or treatment-related risk factors. Alternate donor HCT and HCT in adults is performed infrequently because of a higher risk profile. Transplant-specific risks include conditioning regimen-related toxicity, graft-versus-host disease, graft rejection with marrow aplasia or disease recurrence, and infections associated with immunosuppression and delayed immune reconstitution. The magnitude of risk depends on patient age, clinical status of the underlying disease (eg, organ injury from vasculopathy and iron overload), donor source, and intensity of the conditioning regimen. These risks are commonly monitored and reported in the short term. Documenting very late outcomes is important, but these data are rarely reported because of challenges imposed by patient drop-out and insufficient resources. This report summarizes long-term follow-up results after HCT for hemoglobin disorders, identifies gaps in knowledge, and discusses opportunities for future investigations. This consensus summary will be followed by a second article detailing comprehensive long-term follow-up recommendations to aid in maintaining health in these individuals and identifying late complication risks that could facilitate interventions to improve outcomes.

A trial of unrelated donor marrow transplantation for children with severe sickle cell disease

Children with sickle cell disease experience organ damage, impaired quality of life, and premature mortality. Allogeneic bone marrow transplant from an HLA-matched sibling can halt disease progression but is limited by donor availability. A Blood and Marrow Transplant Clinical Trials Network (BMT CTN) phase 2 trial conducted from 2008 to 2014 enrolled 30 children aged 4 to 19 years; 29 were eligible for evaluation. The primary objective was 1-year event-free survival (EFS) after HLA allele-matched (at HLA-A, -B, -C, and -DRB1 loci) unrelated donor transplant. The conditioning regimen included alemtuzumab, fludarabine, and melphalan. Graft-versus-host disease (GVHD) prophylaxis included calcineurin inhibitor, short-course methotrexate, and methylprednisolone. Transplant indications included stroke (n = 12), transcranial Doppler velocity >200 cm/s (n = 2), ≥3 vaso-occlusive pain crises per year (n = 12), or ≥2 acute chest syndrome episodes (n = 4) in the 2 years preceding enrollment. Median follow-up was 26 months (range, 12-62 months); graft rejection was 10%. The 1- and 2-year EFS rates were 76% and 69%, respectively. The corresponding rates for overall survival were 86% and 79%. The day 100 incidence rate of grade II-IV acute GVHD was 28%, and the 1-year incidence rate of chronic GVHD was 62%; 38% classified as extensive. There were 7 GVHD-related deaths. A 34% incidence of posterior reversible encephalopathy syndrome was noted in the first 6 months. Although the 1-year EFS met the prespecified target of ≥75%, this regimen cannot be considered sufficiently safe for widespread adoption without modifications to achieve more effective GVHD prophylaxis. The BMT CTN #0601 trial was registered at www.clinicaltrials.gov as #NCT00745420.

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

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

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

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

A common signaling pathway is activated in erythroid cells expressing high levels of fetal hemoglobin: a potential role for cAMP-elevating agents in β-globin disorders

Background

Although erythroid cells prepared from fetal liver, cord blood, or blood from β-thalassemia patients are known to express fetal hemoglobin at high levels, the underlying mechanisms remain elusive. We previously showed that cyclic nucleotides such as cAMP and cGMP induce fetal hemoglobin expression in primary erythroid cells. Here we report that cAMP signaling contributes to high-level fetal hemoglobin expression in erythroid cells prepared from cord blood and β-thalassemia.

Methods

The status of the cAMP signaling pathway was investigated using primary erythroid cells prepared from cord blood and the mononuclear cells of patients with β-thalassemia; erythroid cells from adult bone marrow mononuclear cells served as the control.

Results

We found that intracellular cAMP levels were higher in erythroid cells from cord blood and β-thalassemia than from adult bone marrow. Protein kinase A activity levels and cAMP-response element binding protein phosphorylation were higher in erythroid cells from cord blood or β-thalassemia than in adult bone marrow progenitors. Mitogen-activated protein kinase pathways, which play a role in fetal hemoglobin expression, were not consistently activated in cord blood or β-thalassemia erythroid cells. When cAMP signaling was activated in adult erythroid cells, fetal hemoglobin was induced at high levels and associated with reduced expression of BCL11A, a silencer of the β-globin gene.

Conclusion

These results suggest that activated cAMP signaling may be a common mechanism among erythroid cells with high fetal hemoglobin levels, in part because of downregulation of BCL11A. Activation of the cAMP signaling pathway with cAMP-elevating agents may prove to be an important signaling mechanism to reactivate fetal hemoglobin expression in erythroid cells.

Hematopoietic stem cell transplantation in SCD

Hematopoietic stem cell transplantation (HSCT) is the one and only curative therapy available for patient with severe sickle cell disease (SCD). Until today, several hundreds of patients have undergone geno-identical HSCT. More than 200 patients were transplanted in France. The first indication was cerebral vasculopathy. Among both malignant and non-malignant diseases treated with HSCT, the success rate obtained in SCD patients appears as the best one. From the year 2000, more than 95% of transplanted patients survived the HSCT procedure and more than 90% are completely cured and experience a very satisfying health condition post-transplantation. However, the current standard procedure includes a myeloablative conditioning regimen for warranting engraftment. Such regime is linked to severe long-term side effects such as hypofertility. Due to the excellent obtained results, we have to think about a possible widening of indications, a decrease of conditioning intensity and toxicity, and about HSCT from alternative stem cell sources, such as mismatch family donor, unrelated volunteer donor or unrelated cord blood.

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

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

Long-term outcome and evaluation of organ function in pediatric patients undergoing haploidentical and matched related hematopoietic cell transplantation for sickle cell disease

HLA-matched related donor (MRD) hematopoietic stem cell transplantation (HSCT) is a well-established therapy for patients with sickle cell disease (SCD); however, experience using alternative donors, including haploidentical donors, in HSCT for SCD is limited. We report the long-term outcomes of 22 pediatric patients who underwent related donor HSCT for SCD at St. Jude Children's Research Hospital, either a myeloablative sibling MRD HSCT (n = 14) or reduced-intensity parental haploidentical donor HSCT (n = 8). The median patient age was 11.0 ± 3.9 years in the MRD graft recipients and 9.0 ± 5.0 years in the haploidentical donor graft recipients. The median follow-up was 9.0 ± 2.3 years, with an overall survival (OS) of 93% and a recurrence/graft failure rate of 0%, for the MRD cohort and 7.4 ± 2.4 years, with an OS of 75%, disease-free survival of 38%, and disease recurrence of 38%, for the haploidentical donor cohort. We report the long-term hematologic response and organ function in patients undergoing MRD or haploidentical donor HSCT for severe SCD. Our data demonstrate long-term hematologic improvements after HSCT with sustained engraftment, and confirm that HSCT offers long-term protection from common complications of SCD, including stroke, pulmonary hypertension, acute chest, and nephropathy, regardless of donor source.

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)

The Sickle Cell Unrelated Donor Transplant Trial (SCURT trial) of the Blood and Marrow Transplant Clinical Trials Network (BMT CTN) is a phase II study of the toxicity and efficacy of unrelated donor hematopoietic cell transplantation in children with severe sickle cell disease (SCD) using a reduced-intensity conditioning regimen. Here we report the results for the cord blood cohort of this trial. Eight children with severe SCD underwent unrelated donor cord blood transplantation (CBT) following alemtuzumab, fludarabine, and melphalan. Cyclosporine or tacrolimus and mycophenolate mofetil were administered for graft-versus-host disease (GVHD) prophylaxis. Donor/recipient HLA match status was 6 of 6 (n = 1) or 5 of 6 (n = 7), based on low/intermediate-resolution molecular typing at HLA -A, -B, and high-resolution typing at -DRB1. Median recipient age was 13.7 years (range: 7.4-16.2 years), and median weight was 35.0 kg (range: 25.2-90.2 kg). The median pre-cryopreservation total nucleated cell dose was 6.4 × 10(7) /kg (range: 3.1-7.6), and the median postthaw infused CD34 cell dose was 1.5 × 10(5) /kg (range: 0.2-2.3). All patients achieved neutrophil recovery (absolute neutrophil count >500/mm(3)) by day 33 (median: 22 days). Three patients who engrafted had 100% donor cells by day 100, which was sustained, and 5 patients had autologous hematopoietic recovery. Six of 8 patients had a platelet recovery to >50,000/mm(3) by day 100. Two patients developed grade II acute GVHD. Of these, 1 developed extensive chronic GVHD and died of respiratory failure 14 months posttransplantation. With a median follow-up of 1.8 years (range: 1-2.6), 7 patients are alive with a 1-year survival of 100%, and 3 of 8 are alive without graft failure or disease recurrence. Based upon the high incidence of graft rejection after unrelated donor CBT, enrollment onto the cord blood arm of the SCURT trial was suspended. However, because this reduced-intensity regimen has demonstrated a favorable safety profile, this trial remains open to enrollment for unrelated marrow donor transplants. Novel approaches aimed at improving engraftment will be needed before unrelated CBT can be widely adopted for transplanting patients with severe SCD.

NCI, NHLBI/PBMTC first international conference on late effects after pediatric hematopoietic cell transplantation: endocrine challenges-thyroid dysfunction, growth impairment, bone health, & reproductive risks

The endocrine system is highly susceptible to damage by high-dose chemotherapy and/or irradiation before hematopoietic cell transplantation (HCT) during childhood. The specific endocrine organs most affected by HCT include the thyroid gland, the pituitary, and the gonads. In addition, hormones that support development and stability of the skeletal system are also affected. Insufficiency of thyroid hormone is 1 of the most common late sequelae of HCT, and occurs more often in young children. Deficiency in the pituitary's production of growth hormone is a problem of unique concern to the pediatric population. The reproductive risks of HCT depend on the patient's gender and pubertal status at the time of HCT. Pubertal or gonadal failure frequently occurs, especially in females. Infertility risks for both genders remain high, whereas methods of fertility preservation are limited in all but postpubertal males. Bone health post-HCT can be compromised by low bone mineral density as well as avascular necrosis, but the data on both problems in the pediatric HCT population are limited. In this paper, the current state of knowledge, gaps in that knowledge, and recommendations for future research are addressed in detail for each of these systems.

Safety and efficacy of targeted busulfan therapy in children undergoing myeloablative matched sibling donor BMT for sickle cell disease. Bone Marrow Transplant. 2011;46:27-33. [PMID: 20305698 DOI: 10.1038/bmt.2010.60]

Busulfan influences engraftment and toxicities during hematopoietic stem cell transplantation (HSCT). We report our single-institution experience of targeted busulfan therapy for myeloablative, matched sibling donor (MSD) HSCT for sickle cell disease (SCD) and assess the relationships of busulfan levels to engraftment and toxicities. Twenty-seven patients with SCD underwent MSD HSCT from 1993 to 2007, 25 with busulfan measurements. The conditioning regimen was busulfan (initial dose 0.875 mg/kg for 16 doses), CY and antithymocyte globulin. Busulfan area under curve (AUC) was determined with the first dose, and dose adjustments were made to target the desired AUC range. Median AUC was 963 μmol min/L (range 780-1305 μmol min/L). Engraftment occurred in all cases: 21 (84%) full donor chimerism (> 95% donor cells), 4 (16%) partial donor chimerism. Hepatic veno-occlusive disease (VOD) occurred in 8 (32%) patients. Lower AUC was seen with partial donor chimerism (862 ± 73 μmol min/L) versus full donor chimerism (AUC 1018 ± 122 μmol min/L) (P = 0.022). VOD was not associated with busulfan AUC (P = 0.153). Of 25 patients, 24 survived with median follow-up of 4.9 years. Our experience shows that targeting busulfan AUC above the range used in previous multicenter trials appears safe and may contribute to sustained engraftment in SCD.

Hematopoietic stem cell transplantation for hemoglobinopathies: current practice and emerging trends

Despite improvements in the management of thalassemia major and sickle cell disease, treatment complications are frequent and life expectancy remains diminished for these patients. Hematopoietic stem cell transplantation (HSCT) is the only curative option currently available. Existing results for HSCT in patients with hemoglobinopathy are excellent and still improving. New conditioning regimens are being used to reduce treatment-related toxicity and new donor pools accessed to increase the number of patients who can undergo HSCT.

Bone marrow transplantation or hydroxyurea for sickle cell anemia: long-term effects on semen variables and hormone profiles

Ten male subjects affected by sickle cell anemia (SCA) were studied to evaluate the long-term effects of therapies on their fertility. Their ages ranged from 18 to 34 years (median: 32 years). Four subjects were treated by hydroxyurea (HU) and 6 by hematopoietic stem cell transplantation (HSCT). The median follow-up after HU initiation and HSCT was 10.5 years (range: 8-15 years) and 15.5 years (range: 8-21 years), respectively. Three of the 6 in the HSCT group and two of the 4 in the HU group were azoospermic. One HSCT subject had normal semen and hormone variables, showing that normal fertility can occasionally be expected after transplantation in SCA. The remaining 4 patients (2 HSCT and 2 HU) were oligozoospermic. With regard to HU, semen impairment appears to be related to the duration of treatment. To draw general conclusions, further research with a large number of patients treated since childhood with HU or HSCT is warranted.

Blood and marrow transplantation for sickle cell disease: overcoming barriers to success

PURPOSE OF REVIEW

Sickle cell disease (SCD) is a common health problem in the United States; yet, the only curative therapy, a bone marrow transplant (BMT), is seldom applied. The objective of this report is to review the most recent clinical trials involving blood and BMT for SCD and to discuss novel approaches to overcome the many barriers to successful use of BMT for SCD.

RECENT FINDINGS

In select patients, disease-free and overall survival is greater than 80% following matched sibling BMT for SCD. Unfortunately, most patients with SCD do not have a suitable human lymphocyte antigen-matched sibling donor. In an attempt to expand the donor pool, several groups are beginning to explore the use of alternative sources of stem cells such as haploidentical donors and umbilical cord cell blood.

SUMMARY

The curative potential of BMT in SCD is irrefutable, with outstanding results in children following a myeloablative conditioning regimen and a matched sibling donor transplant. Well tolerated and effective application of alternative sources of stem cells for BMT in SCD could greatly increase the cure rate for this devastating disease.

Allogeneic hematopoietic cell transplantation for primary immune deficiency diseases: current status and critical needs

Allogeneic hematopoietic cell transplantation (HCT) has been used for 40 years to ameliorate or cure primary immune deficiency (PID) diseases, including severe combined immunodeficiency (SCID) and non-SCID PID. There is a critical need for evaluation of the North American experience of different HCT approaches for these diseases to identify best practices and plan future investigative clinical trials. Our survey of incidence and prevalence of PID in North American practice sites indicates that such studies are feasible. A conference of experts in HCT treatment of PID has recommended (1) a comprehensive cross-sectional and retrospective analysis of HCT survivors with SCID; (2) a prospective study of patients with SCID receiving HCT, with comparable baseline and follow-up testing across participating centers; (3) a pilot study of newborn screening for SCID to identify affected infants before compromise by infection; and (4) studies of the natural history of disease in patients who do or do not receive HCT for the non-SCID diseases of Wiskott-Aldrich syndrome and chronic granulomatous disease. To accomplish these goals, collaboration by a consortium of institutions in North America is proposed. Participation of immunologists and HCT physicians having interest in PID and experts in laboratory methods, clinical outcomes assessment, databases, and analysis will be required for the success of these studies.

Hematopoietic cell transplantation: a curative option for sickle cell disease

Sickle cell disease is associated with considerable morbidity and premature mortality. Hematopoietic cell transplantation offers the possibility of cure and is associated with excellent results in pediatric patients receiving stem cell transplantation from a matched sibling donor. Reduced intensity conditioning regimen have the potential to further reduce regimen related morbidity and mortality. Improved understanding of the natural history of complications such as stroke and pulmonary hypertension, effects of treatments, such as hydroxyurea and blood transfusions, as well as the impact of transplantation on organ damage are likely to influence the timing and indication of transplantation. Improvements in preparative regimen may enable the safe use of alternate source of stem cells such as unrelated matched donors and further improve the applicability and acceptability of this treatment.

Has stem cell transplantation come of age in the treatment of sickle cell disease?

Currently, hematopoietic SCT (HCT) is the only intervention that can restore normal hematopoiesis to provide a 'cure' in sickle cell disease. Yet, this treatment modality is used sparsely-a total of less than 400 transplants are reported in the Center for International Blood and Marrow Transplant Research database despite 70,000 afflicted in the United States; 88% of transplants are from HLA-matched sibling donors and 84% are <16 years of age at transplant. Overall survival at 3 years is over 90% after HCT in the young but 62% in adult HCT recipients due to increased disease and transplant-related morbidity. The decision and timing of HCT is a dilemma for physicians and families due to the need to consider HCT before severe organ damage in a disease that is generally not fatal in children with adequate supportive care. From the transplant physician's perspective, however, advances in the ability to identify well-matched donors, supportive care and promising conditioning regimens with low toxicity and transplant complications support the development of new HCT trials for sickle cell disease as the risk/benefit ratio can be balanced better. With the recognition of new predictors of early mortality, the anticipation of extensive and expensive life-long medical support, and the poor quality of life despite medical care, the scales tip in favor of HCT. This is prime time for the development of careful unrelated donor HCT trials for sickle cell disease. Research efforts targeting HCT will need to be directed at seeking safe and effective transplant methods applicable to all patients who might derive benefit.