Late Effects Screening Guidelines after Hematopoietic Cell Transplantation (HCT) for Hemoglobinopathy: Consensus Statement from the Second Pediatric Blood and Marrow Transplant Consortium International Conference on Late Effects after Pediatric HCT

Strategic infection prevention after genetically modified hematopoietic stem cell therapies: recommendations from the International Society for Cell & Gene Therapy Stem Cell Engineering Committee

There is lack of guidance for immune monitoring and infection prevention after administration of ex vivo genetically modified hematopoietic stem cell therapies (GMHSCT). We reviewed current infection prevention practices as reported by providers experienced with GMHSCTs across North America and Europe, and assessed potential immunologic compromise associated with the therapeutic process of GMHSCTs described to date. Based on these assessments, and with consensus from members of the International Society for Cell & Gene Therapy (ISCT) Stem Cell Engineering Committee, we propose risk-adapted recommendations for immune monitoring, infection surveillance and prophylaxis, and revaccination after receipt of GMHSCTs. Disease-specific and GMHSCT-specific considerations should guide decision making for each therapy.

Improvement in Cardiac Morphology Demonstrated by Cardiac Magnetic Resonance Imaging and Echocardiography after Haploidentical Hematopoietic Cell Transplantation in Adults with Sickle Cell Disease

Cardiopulmonary complications account for approximately 40% of deaths in patients with sickle cell disease (SCD). Diffuse myocardial fibrosis, elevated tricuspid regurgitant jet velocity (TRV) and iron overload are all associated with early mortality. Although HLA-matched sibling hematopoietic cell transplantation (HCT) offers a potential cure, less than 20% of patients have a suitable donor. Haploidentical HCT allows for an increased donor pool and has recently demonstrated improved safety and efficacy. Our group has reported improved cardiac morphology via echocardiography at 1 year after HCT. Here we describe the first use of cardiac magnetic resonance imaging (CMR), the gold standard for measuring volume, mass, and ventricular function, to evaluate changes in cardiac morphology post-HCT in adults with SCD. We analyzed baseline and 1-year data from 12 adults with SCD who underwent nonmyeloablative haploidentical peripheral blood HCT at the National Institutes of Health. Patients underwent noncontrast CMR at 3 T, echocardiography, and laboratory studies. At 1 year after HCT, patients showed marked improvement in cardiac chamber morphology by CMR, including left ventricular (LV) mass (70.2 to 60.1 g/m2; P = .02) and volume (114.5 to 90.6 mL/m2; P = .001). Furthermore, mean TRV normalized by 1 year, suggesting that HCT may offer a survival benefit. Fewer patients had pathologically prolonged native myocardial T1 times, an indirect marker of myocardial fibrosis at 1 year; these data showed a trend toward significance. In this small sample, CMR was very sensitive in detecting cardiac mass and volume changes after HCT and provided complementary information to echocardiography. Notably, post-HCT improvement in cardiac parameters can be attributed only in part to the resolution of anemia; further studies are needed to determine the roles of myocardial fibrosis reversal, improved blood flow, and survival impact after HCT for SCD.

The value of using patient-reported outcomes for health screening during long-term follow-up after paediatric stem cell transplantation for nonmalignant diseases

INTRODUCTION

The assessment of using patient-reported outcomes (PROs) within comprehensive care follow-up programmes, specifically focused on health screening, remains largely unexplored. PROs were implemented in our late effects and comprehensive care programme after paediatric hematopoietic stem cell transplantation (HSCT) for nonmalignant diseases. The programme focuses solely on screening of physical and mental health and on discussing PROs during the consultation.

METHODS

The primary method of this study was semistructured interviews to explore the perspective of both patients and healthcare providers' (HCP) on the use of PROs, which were thematically analyzed. Additionally, an explorative quantitative approach with patient-reported experience measures (PREMS) was used, with a pretest-posttest design, to assess whether the use of PROs was accompanied by more patient-centred care.

RESULTS

From the patient-interviews (N = 15) four themes were extracted: use of PROs (1) help to discuss topics; (2) make the patients feel understood; (3) create a moment of self-reflection; and (4) make consultations more efficient. Pre- and postimplementation analysis of PREMs (N = 40) did not show significant differences in terms of patient-centeredness.

CONCLUSION

Our results demonstrate the added value of integrating PROs for health screening purposes within the long-term follow-up programme after paediatric HSCT, as perceived by both patient and HCP. With the active use of PROs, patients are stimulated to consciously assess their health status.

PATIENT CONTRIBUTION

This study included patients as participants. Caregivers were approached if patients were below a certain age. Additionally, preliminary results were shared with all patients (including nonparticipants) during a patient conference day.

Health-Related Quality-of-Life Profile of Pediatric Patients with β Thalassemia after Hematopoietic Stem Cell Transplantation

Matched hematopoietic stem cell transplantation (HSCT) is a feasible and curative treatment in pediatric patients with beta thalassemia major (β-TM). However, little data are available regarding patients and their parents' health-related quality of life (HRQoL) after the procedure. As such, we investigated the HRQoL of pediatric patients with β-TM after HSCT compared to that of patients treated with blood transfusions and iron chelation. The health-related quality of life of 43 β-TM pediatric patients and 43 parents were evaluated using the Pediatric Quality of Life Inventory (PedsQL). A total of 25 patients underwent HSCT: 15 from a sibling and 10 from an HLA-matched donor. The median follow-up time from HSCT was 5 years (range 1-13 years). The mean ages at the survey were 10.1 years (range 5-15) and 9.6 years (range 5-15) for transfused and transplanted patients, respectively. A significant reduction in HRQoL was reported in the group of transfused patients compared with that of patients transplanted in the following PedsQL domains: children's and parents' physical functions, Δ = -15.4, p = 0.009 and Δ = -11.3, p = 0.002, respectively; children's and parents' emotional functioning, Δ = -15.2, p = 0.026 and Δ = -15.2, p = 0.045, respectively; child's and parents' school functioning, Δ = -25, p = 0.005 and Δ = -22.5, p = 0.011, respectively; total child and parents scores, Δ = -14.5, p = 0.004 and Δ = -13.2, p = 0.005, respectively. The results of a multivariable analysis showed that the HSCT procedure was significantly associated with a higher total child PedsQL score (adjusted mean difference = 15.3, p = 0.001) and a higher total parent PedsQL score (adjusted mean difference = 14.1, p = 0.006). We found no significant difference in the HRQoL measured after sibling or unrelated human leukocyte antigen (HLA)-matched HSCT. Finally, a significant positive correlation across all the PedsQL domains was found between the scores reported by the children and those reported by their parents. In conclusion, our study shows that HSCT in pediatric patients with β-TM is associated with a good overall HRQoL profile. This information further supports physicians when counseling patients and their parents before the HSCT procedure.

Female Reproductive Health Outcomes after Hematopoietic Cell Transplantation for Sickle Cell Disease: Is Reduced Intensity Better Than Myeloablative Conditioning?

Curative therapy for sickle cell disease (SCD) through hematopoietic cell transplantation (HCT) is associated with a high level of risk for treatment-related gonadal dysfunction and future infertility. Both the myeloablative conditioning (MAC) and reduced-intensity conditioning (RIC) regimens used for SCD HCT are considered to carry a high risk for ovarian damage. Cyclophosphamide equivalent doses (CEDs) are thought to correlate with the degree of gonadal damage in pediatric oncology patients. We aimed to evaluate ovarian outcomes previously reported from our center, characterize the conditioning regimens as MAC or RIC, and calculate the CED for each regimen. The ovarian outcomes diminished ovarian reserve (DOR), as determined by an anti-Müllerian hormone (AMH) below the normal limits for age and assay or <5%, and premature ovarian insufficiency (POI), defined as a follicle-stimulating hormone (FSH) level >40 mIU/ML, are presented by conditioning regimen from 3 clinical studies from our center (2 published and 1 presented as an abstract in 2022). The studies were not mutually exclusive of patients. CEDs were calculated for each regimen. The CED ranged from 3388 to 9705 mg/m2 for MAC regimens and from 5600 to 18,750 mg/m2 for RIC regimens. DOR was observed in all regimens; however, in one study 2 patients had normal AMH levels after a fludarabine/melphalan regimen, and 1 patient had a normal AMH level after a fludarabine/melphalan/thiotepa regimen. Rates of POI were more variable and ranged from 40% to 100% after MAC regimens and from 0 to 100% after RIC regimens. Female patients with SCD who undergo HCT have very high rates of DOR after both MAC HCT and RIC HCT. Two of the 3 RIC regimens evaluated had higher CEDs than were seen in any of the MAC regimens evaluated. Rates of POI were more variable but may increase with time from transplantation. All SCD patients need to be counseled about the risk of infertility and provided information about fertility preservation.

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.

Reduction in vaso-occlusive events following stem cell transplantation in patients with sickle cell disease

Hematopoietic stem cell transplantation (HSCT) is potentially curative for patients with sickle cell disease (SCD). Patients with stable donor engraftment after allogeneic HSCT generally do not experience SCD-related complications; however, there are no published data specifically reporting the change in vaso-occlusive events (VOE) after HSCT. Data regarding the number of VOEs requiring medical attention in the 2 years before allogeneic HSCT were compared with the number of VOEs in the 2 years (0-12 months and 12-24 months) after allogeneic HSCT in patients with SCD. One-hundred sixty-three patients with SCD underwent allogeneic HSCT between 2005 and 2019. The average age at the time of HSCT was 21 years (range, 7 months - 64 years). Most patients underwent nonmyeloablative conditioning (75% [N = 123]) and had a matched sibling donor (72% [N = 118]). The mean number of VOEs was reduced from 5.6 (range, 0-52) in the 2 years before HSCT to 0.9 (range, 0-12) in the 2 years after HSCT (P < .001). Among the post-HSCT events, VOE was more frequent during the first 12 months (0.8 [range, 0-12]) than at 12 to 24 months after HSCT (0.1 [range, 0-8) (P < .001)). In patients who had graft rejection (12%, N = 20), VOEs were reduced from 6.6 (range, 0-24) before HSCT to 1.1 (range, 0-6) and 0.8 (range, 0-8) at 0 to 12 months and 12 to 24 months after HSCT, respectively (P < .001). VOEs requiring medical care were significantly reduced after allogeneic HSCT for patients with SCD. These data will inform the development of novel autologous HSCT gene therapy approaches.

Long-Term Organ Function After HCT for SCD: A Report From the Sickle Cell Transplant Advocacy and Research Alliance

Hematopoietic cell transplantation (HCT) is an established cure for sickle cell disease (SCD) supported by long-term survival, but long-term organ function data are lacking. We sought to describe organ function and assess predictors for dysfunction in a retrospective cohort (n = 247) through the Sickle cell Transplant Advocacy and Research alliance. Patients with <1-year follow-up or graft rejection/second HCT were excluded. Organ function data were collected from last follow-up. Primary measures were organ function, comparing pre- and post-HCT. Bivariable and multivariable analyses were performed for predictors of dysfunction. Median age at HCT was 9.4 years; the majority had HbSS (88.2%) and severe clinical phenotype (65.4%). Most received matched related (76.9%) bone marrow (83.3%) with myeloablative conditioning (MAC; 57.1%). Acute and chronic graft-versus-host disease (GVHD) developed in 24.0% and 24.8%. Thirteen patients (5.3%) died ≥1 year after HCT, primarily from GVHD or infection. More post-HCT patients had low ejection or shortening fractions than pre-HCT (0.6% → 6.0%, P = .007 and 0% → 4.6%, P = .003). The proportion with lung disease remained stable. Eight patients (3.2%) had overt stroke; most had normal (28.3%) or stable (50.3%) brain magnetic resonance imaging. On multivariable analysis, cardiac dysfunction was associated with MAC (odds ratio [OR] = 2.71; 95% confidence interval [CI], 1.09-6.77; P = .033) and severe acute GVHD (OR = 2.41; 95% CI, 1.04-5.62; P = .041). Neurologic events were associated with central nervous system indication (OR = 2.88; 95% CI, 2.00-4.12; P < .001). Overall organ dysfunction was associated with age ≥16 years (OR = 2.26; 95% CI, 1.35-3.78; P = .002) and clinically severe disease (OR = 1.64; 95% CI, 1.02-2.63; P = .043). In conclusion, our results support consideration of HCT at younger age and use of less intense conditioning.

Organ function indications and potential improvements following curative therapy for sickle cell disease

Curative therapies for sickle cell disease include allogeneic hematopoietic stem cell transplantation (HSCT) and gene-modified autologous stem cell transplantation. HSCT has been used for 30 years with success measured by engraftment, symptom control, graft-vs-host disease (GVHD) risk, organ toxicity, and immune reconstitution. While human leukocyte antigen-matched sibling donor (MSD) transplants have excellent outcomes, alternate donor transplants (unrelated/haploidentical) are just beginning to overcome GVHD and engraftment hurdles to match MSD. Gene therapy, a newly developed treatment, is undergoing careful evaluation in many trials with varying approaches. The risk/benefit ratio to the patient in relation to outcomes, toxicities, and mortality risk drives eligibility for curative interventions. Consequently, eligibility criteria for MSD transplants can be less stringent, especially in the young. Posttransplant outcome analysis after the "cure" with respect to organ function recovery is essential. While established damage such as stroke is irreversible, transplant can help stabilize (pulmonary function), prevent further deterioration (stroke), improve (neurocognition), and protect unaffected organs. Tracking organ functions postintervention uniformly between clinical trials and for adequate duration is essential to answer safety and efficacy questions related to curative therapies. Age-appropriate application/outcome analyses of such therapies will be the ultimate goal in overcoming this disease.

Long-term health outcomes following curative therapies for sickle cell disease

Treatment options for patients with sickle cell disease (SCD) continue to rapidly expand and evolve. The goal of therapies such as an allogeneic hematopoietic stem cell transplant (HSCT), gene therapy, and gene editing is to cure rather than control SCD. The benefits of these therapies must be accompanied by minimizing long-term adverse health outcomes from SCD and its treatment. SCD can have adverse effects on a variety of organ systems, including the heart, lung, kidney, and reproductive system, leading to high disease burden, morbidity, and premature mortality in both pediatric and adult patients. While curative therapies are being increasingly used, there remains a paucity of data on the long-term health outcomes associated with these treatments in children and adults with SCD. There are data available regarding the effects of HSCT performed largely for malignant diseases, from which data on SCD outcomes may be extrapolated. However, given the significant differences between these 2 populations of patients who undergo HSCT, such extrapolation is imprecise at best. Furthermore, there are currently no published data on long-term health outcomes following gene therapy for SCD due to current short follow-up times. We summarize the limited data reported on health outcomes following HSCT for SCD and emphasize the need for more research within this area.

Survival and late effects of hematopoietic cell transplantation in patients with thalassemia major

In this retrospective study, we evaluated long-term survival and late effects in 137 patients affected by thalassemia major (TM) who received an allogeneic hematopoietic cell transplantation (HCT). Median age at HCT was 10.1 years. After a median follow-up of 30 years, 114 (83.2%) patients are living and 108 (78.8%) are cured. The cumulative incidence of nonrelapse mortality and thalassemia recurrence was 9.5% at 1 year and 10.2% at 39 years respectively. The 39-years cumulative incidence of overall survival and disease-free survival were 81.4% and 74.5%. One hundred twenty-three patients who survived more than 2 years after HCT were evaluated for late effects concerning hematological disorders, iron burden, growth, obesity, diabetes mellitus, thyroid and gonadal function, eye, heart, liver, lung, kidney, gastrointestinal, neurologic and psychiatric system, osteoarticular system, secondary solid cancer (SSC), performance status, and Covid-19 infection. Fertility was preserved in 21 males whose partners delivered 34 neonates and 25 females who delivered 26 neonates. Fifteen cases of SSC were diagnosed for a 39-year cumulative incidence of 16.4%. HCT represents a definitive cure for the majority of TM patients at the price, however, of a non-negligible early and late mortality which in the long run affects survival and disease-free survival.

Late endocrine effects after hematopoietic stem cell transplantation in children with nonmalignant diseases

The number of children undergoing hematopoietic stem cell transplantation (HSCT) for nonmalignant diseases has increased in recent years. Endocrine complications are common after HSCT for malignant diseases, while little is known about long-term prevalence and risk factors in children transplanted for nonmalignant diseases. We retrospectively evaluated gonadal function, near adult height and thyroid function in 197 survivors of pediatric HSCT for hemoglobinopathies (n = 66), inborn errors of immunity/metabolism (n = 74) and bone marrow failure disorders (n = 57); median follow-up was 6.2 years (range 3.0-10.5). Gonadal dysfunction occurred in 55% of (post)pubertal females, was still present at last assessment in 43% and was more common after busulfan- than treosulfan-based conditioning (HR 10.6, CI 2.2-52.7; adjusted for HSCT indication). Gonadal dysfunction occurred in 39% of (post)pubertal males, was still present at last assessment in 32% and was less common in those who were prepubertal compared to (post)pubertal at HSCT (HR 0.11; CI 0.05-0.21). Near adult height was more than 2 SDS below mean parental height in 21% of males and 8% of females. Hypothyroidism occurred in 16% of patients; 4% received thyroxin treatment. In conclusion, endocrine complications, especially gonadal dysfunction, are common after pediatric HSCT for nonmalignant conditions. In females, treosulfan seems less gonadotoxic than busulfan. Careful long-term endocrine follow-up is indicated.

Sickle Cell Transplantation Evaluation of Long-term and Late Effects Registry (STELLAR) to Compare Long-term Outcomes After Hematopoietic Cell Transplantation to Those in Siblings Without Sickle Cell Disease and in Nontransplanted Individuals With Sickle Cell Disease: Design and Feasibility Study

BACKGROUND

There are sparse data on the long-term and late effects of hematopoietic cell transplantation (HCT) for sickle cell disease (SCD).

OBJECTIVE

This study aims to establish an international registry of long-term outcomes post-HCT for SCD and demonstrate the feasibility of recruitment at a single site in the United States.

METHODS

The Sickle Cell Transplantation Evaluation of Long-Term and Late Effects Registry (STELLAR) was designed to enroll patients with SCD ≥1 year post-HCT, their siblings without SCD, and nontransplanted controls with SCD to collect web-based participant self-reports of health status and practices by using the Bone Marrow Transplant Survivor Study (BMTSS) surveys, health-related quality of life (HRQOL) using the Patient-Reported Outcomes Measurement Information System (PROMIS) Pediatric Profile-25 or Pediatric Profile-29 survey, chronic graft-versus-host disease (cGVHD) using the symptom scale survey, daily pain using an electronic pain diary, the economic impact of HCT using the financial hardship survey, sexual function using the PROMIS Sexual Function SexFSv2.0 survey, and economic productivity using the American Time Use Survey (ATUS). We also piloted retrieval of clinical data previously submitted to the Center for International Blood and Marrow Transplant Research (CIBMTR); recorded demographics, height, weight, blood pressure, waist and hip circumferences, timed up and go (TUG) test, and handgrip test; and obtained blood for metabolic screening, gonadal function, fertility potential, and biorepository of plasma, serum, RNA, and DNA.

RESULTS

Of 100 eligible post-HCT patients, we enrolled 72 (72%) participants aged 9-38 (median 17) years. We also enrolled 19 siblings aged 5-32 (median 10) years and 28 nontransplanted controls with SCD aged 4-46 (median 22) years. Of the total 119 participants, 73 (61%) completed 85 sets of surveys and 41 (35%) contributed samples to the biorepository. We completed ATUS interviews of 28 (24%) participants. We successfully piloted retrieval of data submitted to the CIBMTR and expanded recruitment to multiple sites in the United States, Canada, the United Kingdom, and Nigeria.

CONCLUSIONS

It is feasible to recruit subjects and conduct study procedures for STELLAR in order to determine the long-term and late effects of HCT for SCD.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/36780.

Long-Term Health Effects of Curative Therapies on Heart, Lungs, and Kidneys for Individuals with Sickle Cell Disease Compared to Those with Hematologic Malignancies

The goal of curing children and adults with sickle cell disease (SCD) is to maximize benefits and minimize intermediate and long-term adverse outcomes so that individuals can live an average life span with a high quality of life. While greater than 2000 individuals with SCD have been treated with curative therapy, systematic studies have not been performed to evaluate the long-term health effects of hematopoietic stem cell transplant (HSCT) in this population. Individuals with SCD suffer progressive heart, lung, and kidney disease prior to curative therapy. In adults, these sequalae are associated with earlier death. In comparison, individuals who undergo HSCT for cancer are heavily pretreated with chemotherapy, resulting in potential acute and chronic heart, lung, and kidney disease. The long-term health effects on the heart, lung, and kidney for children and adults undergoing HSCT for cancer have been extensively investigated. These studies provide the best available data to extrapolate the possible late health effects after curative therapy for SCD. Future research is needed to evaluate whether HSCT abates, stabilizes, or exacerbates heart, lung, kidney, and other diseases in children and adults with SCD receiving myeloablative and non-myeloablative conditioning regimens for curative therapy.

Evidence-Based Minireview: In young children with severe sickle cell disease, do the benefits of HLA-identical sibling donor HCT outweigh the risks?

In case 1, a 14-month-old male child with sickle cell disease (SCD) was referred for evaluation for an allogeneic hematopoietic stem cell transplant (HCT). The patient had a history of dactylitis 3 times in his first year of life and febrile episodes twice at the consult. His 4-year-old sister was found to be human leukocyte antigen (HLA) identical. The patient was started on hydroxyurea (HU) at 2.5 years of age. His parents again sought consultation when he was 5 years old because of concerns about his medical condition. At the time, the patient had experienced 2 vaso-occlusive pain episodes (VOEs) requiring hospitalization during the previous 2 years. He had also experienced intermittent pain crises requiring rest at home for 2 to 3 days. The child has not attended school in person due to the COVID-19 pandemic. The family is considering HCT but is ambivalent about it because of potential toxicity. In case 2, an 8-year-old female child is 3 years out from HCT for SCD from her HLA-identical sibling. Before HCT, despite receiving HU, she had experienced >5 VOEs requiring hospitalization and 2 episodes of acute chest syndromes in the previous 3 years. She had also been missing almost 50 days of school days each year. After HCT, she is now attending school regularly and participating in all normal age-appropriate activities. The parents believe that HCT has been transformative in their child's life.

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.

Pulmonary surveillance in pediatric hematopoietic stem cell transplant: A multinational multidisciplinary survey

Background

Hematopoietic Stem Cell Transplant (HSCT) is an established treatment for malignant and non‐malignant conditions and pulmonary disease is a leading cause of late term morbidity and mortality. Accurate and early detection of pulmonary complications is a critical step in improving long term outcomes. Existing guidelines for surveillance of pulmonary complications post‐HSCT contain conflicting recommendations.

Aim

To determine the breadth of current practice in monitoring for pulmonary complications of pediatric HSCT.

Methods

An institutional review board approved, online, anonymous multiple‐choice survey was distributed to HSCT and pulmonary physicians from the United States of America and Australasia using the REDcap platform. The survey was developed by members of the American Thoracic Society Working Group on Complications of Childhood Cancer, and was designed to assess patient management and service design.

Results

A total of 40 (34.8%) responses were received. The majority (62.5%) were pulmonologists, and 82.5% were from the United States of America. In all, 67.5% reported having a protocol for monitoring pulmonary complications and 50.0% reported adhering “well” or “very well” to protocols. Pulmonary function tests (PFTs) most commonly involved spirometry and diffusion capacity for carbon monoxide. The frequency of PFTs varied depending on time post‐HSCT and presence of complications. In all, 55.0% reported a set threshold for a clinically significant change in PFT.

Conclusions

These results illustrate current variation in surveillance for pulmonary complications of pediatric HSCT. The results of this survey will inform development of future guidelines for monitoring of pulmonary complications after pediatric HSCT.

Chronic kidney disease ten years after pediatric allogeneic hematopoietic stem cell transplantation

Chronic kidney disease (CKD) is an important sequela of hematopoietic stem cell transplantation (HSCT), but data regarding CKD after pediatric HSCT are limited. In this single center cohort study, we evaluated the estimated glomerular filtration rate (eGFR) dynamics, proteinuria and hypertension in the first decade after HSCT and assessed risk factors for CKD in 216 pediatric HSCT survivors, transplanted 2002-2012. The eGFR decreased from a median of 148 to 116 ml/min/1.73 m² between pre-HSCT to ten years post-HSCT. CKD (KDIGO stages G2 or A2 or more; eGFR under 90 ml/min/1.73m² and/or albuminuria) occurred in 17% of patients. In multivariate analysis, severe prolonged stage 2 or more acute kidney injury (AKI), with an eGFR under 60ml/min/1.73m² and duration of 28 days or more, was the main risk factor for CKD (hazard ratio 9.5, 95% confidence interval 3.4-27). Stage 2 or more AKI with an eGFR of 60ml/min/1.73m² or more and KDIGO stage 2 or more AKI with eGFR under 60ml/min/1.73m² but recovery within 28 days were not associated with CKD. Furthermore, hematological malignancy as HSCT indication was an independent risk factor for CKD. One third of patients had both CKD criteria, one third had isolated eGFR reduction and one third only had albuminuria. Hypertension occurred in 27% of patients with CKD compared to 4.4% of patients without. Tubular proteinuria was present in 7% of a subgroup of 71 patients with available β2-microglobulinuria. Thus, a significant proportion of pediatric HSCT recipients developed CKD within ten years. Our data stress the importance of structural long-term monitoring of eGFR, urine and blood pressure after HSCT to identify patients with incipient CKD who can benefit from nephroprotective interventions.

Hematopoietic stem cell transplant referral patterns for children with sickle cell disease vary among pediatric hematologist/oncologists' practice focus: A Sickle Cell Transplant Advocacy and Research Alliance (STAR) study

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) provides a curative therapy for children severely affected by sickle cell disease (SCD). Rejection-free survival after matched sibling donor (MSD) HSCT is very high, but adoption of HSCT as a curative SCD therapy has been slow. In this study, we assess providers' perceptions about MSD HSCT for children with variable SCD severity, and determine the influence of provider characteristics on HSCT referrals.

PROCEDURE

After our Institutional Review Board deemed the study exempt, American Society of Pediatric Hematology/Oncology Clinical Forum listserv subscribers and American Society of Hematology members who self-identified as pediatric hematologists/oncologists (PHO) were emailed a survey. Analysis was performed to describe and evaluate correlations between participant demographics (including practice focus within PHO) and likelihood of HSCT referral for each scenario.

RESULTS

Spearman's rank correlation analysis did not reveal any significant relationship between demographic characteristics except practice focus and likelihood to refer to HSCT for any scenarios. Providers focused on SCD and HSCT were more likely to refer a child who had never been admitted to the hospital or had suboptimal adherence to hydroxyurea than general PHOs. A significantly higher proportion of all respondents would refer a child with β-thalassemia major (87%) than an asymptomatic child with HbSS (47%, P < .00001) or non-HbSS variant (23%, P < .00001).

CONCLUSION

PSCD and HSCT physicians are more likely to refer for MSD HSCT in almost every condition than general PHO practitioners, likely because of increased awareness of long-term effects of SCD and safety of MSD HSCT for children with SCD.

The role of haematopoietic stem cell transplantation for sickle cell disease in the era of targeted disease-modifying therapies and gene editing

Sickle cell disease is one of the most common, life-threatening, non-communicable diseases in the world and a major public health problem. Following the implementation of simple preventive and therapeutic modalities, infant mortality has almost been abolished in high-income countries, but only a small amount of progress has been made in improving survival in adulthood. Progressive end-organ damage, partly related to a systemic vasculopathy, is increasingly recognised. With the availability of a variety of novel disease-modifying drugs, gene addition and gene editing strategies, matched sibling donor haematopoietic stem cell transplantation (HSCT) in children (offering an overall survival rate of 95% and an event-free survival rate of 92%), and encouraging outcomes after alternative donor HSCT, the new challenge is to risk stratify patients, revise transplantation indications, and define the best therapeutic approach for each patient. The ultimate challenge will be to enable these advances in low-income and middle-income countries, where disease prevalence is highest and where innovative strategies are most needed.

Transplant characteristics and self-reported pulmonary outcomes in Swiss childhood cancer survivors after hematopoietic stem cell transplantation-a cohort study

Childhood cancer survivors treated with hematopoietic stem cell transplantation are at high risk for pulmonary morbidity and mortality. In this retrospective study we described transplant characteristics of pediatric patients who underwent hematopoietic stem cell transplantation in Switzerland and how these characteristics changed over time, compared self-reported pulmonary outcomes between transplanted and non-transplanted survivors, and investigated risk factors for the reported pulmonary outcomes. As part of the population-based Swiss Childhood Cancer Survivor Study, we sent questionnaires to all ≥5-year childhood cancer survivors diagnosed 1976–2010 at age ≤20 years. We included 132 transplanted survivors and 368 matched non-transplanted survivors. During the study period transplant characteristics changed, with decreasing use of total body irradiation and increased use of peripheral blood stem cells and mismatched and unrelated donors as transplant source. One-fifth of transplanted survivors (20%, 95%CI 13–27%) and 18% of non-transplanted survivors (95%CI 13–21%) reported at least one pulmonary outcome. None of the analyzed factors was significantly associated with an increased risk of pulmonary outcomes in multivariable analysis. We found that pulmonary outcomes were frequently reported in transplanted and non-transplanted childhood cancer survivors, indicating a strong need for long-term pulmonary follow-up care.

Subsequent neoplasms and late mortality in children undergoing allogeneic transplantation for nonmalignant diseases

We examined the risk of subsequent neoplasms (SNs) and late mortality in children and adolescents undergoing allogeneic hematopoietic cell transplantation (HCT) for nonmalignant diseases (NMDs). We included 6028 patients (median age, 6 years; interquartile range, 1-11; range, <1 to 20) from the Center for International Blood and Marrow Transplant Research (1995-2012) registry. Standardized mortality ratios (SMRs) in 2-year survivors and standardized incidence ratios (SIRs) were calculated to compare mortality and SN rates with expected rates in the general population. Median follow-up of survivors was 7.8 years. Diagnoses included severe aplastic anemia (SAA; 24%), Fanconi anemia (FA; 10%), other marrow failure (6%), hemoglobinopathy (15%), immunodeficiency (23%), and metabolic/leukodystrophy syndrome (22%). Ten-year survival was 93% (95% confidence interval [95% CI], 92% to 94%; SMR, 4.2; 95% CI, 3.7-4.8). Seventy-one patients developed SNs (1.2%). Incidence was highest in FA (5.5%), SAA (1.1%), and other marrow failure syndromes (1.7%); for other NMDs, incidence was <1%. Hematologic (27%), oropharyngeal (25%), and skin cancers (13%) were most common. Leukemia risk was highest in the first 5 years posttransplantation; oropharyngeal, skin, liver, and thyroid tumors primarily occurred after 5 years. Despite a low number of SNs, patients had an 11-fold increased SN risk (SIR, 11; 95% CI, 8.9-13.9) compared with the general population. We report excellent long-term survival and low SN incidence in an international cohort of children undergoing HCT for NMDs. The risk of SN development was highest in patients with FA and marrow failure syndromes, highlighting the need for long-term posttransplantation surveillance in this population.

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.

Functional and Radiologic Assessment of the Brain after Reduced-Intensity Unrelated Donor Transplantation for Severe Sickle Cell Disease: Blood and Marrow Transplant Clinical Trials Network Study 0601

Stroke and cognitive decline are hallmarks of sickle cell disease (SCD). The natural history of SCD predicts progressive loss of 1 IQ point per year attributable to disease-related pathology. Hematopoietic cell transplantation (HCT) is curative by reverting to donor-derived erythropoiesis, but evidence that HCT can positively influence disease-induced cognitive decline is lacking. The Sickle Cell Unrelated Transplant Trial prospectively evaluated cognition and brain magnetic resonance imaging (MRI) findings at 2 years after reduced-intensity conditioning followed by unrelated donor HCT. Thirteen study participants completed pre-HCT and post-HCT assessments of intelligence. The mean age of participants was 12.5 ± 3.3 years (range, 6.7 to 17.4 years). Eleven of the 13 recipients completed imaging studies at baseline and post-HCT. Seven had overt stroke pre-HCT, and 1 had an elevated transcranial Doppler velocity with abnormal MRI. The mean Full-Scale IQ was stable: 90.9 ± 13 at baseline and 91.2 ± 13 post-HCT. The mean Performance IQ was 89.9 ± 13 at baseline versus 90.9 ± 13 post-HCT, and mean Verbal IQ was 93.4 ± 13 at baseline versus 93.2 ± 13 post-HCT, respectively. Six recipients had stable MRI; 2 showed resolution of all areas of infarction. Three had additional infarcts post-HCT noted at the 2-year time point. This is the first report describing stabilization of IQ and central nervous system outcomes after unrelated donor HCT despite previous central nervous system morbidity and post-HCT posterior reversible encephalopathy syndrome. These preliminary results post-HCT suggest that HCT may stabilize the cognitive decline of SCD and should continue to be followed over the long term.

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

INTRODUCTION

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