Favorable outcomes of hematopoietic stem cell transplantation in children and adolescents with Diamond-Blackfan anemia

Towards a Cure for Diamond-Blackfan Anemia: Views on Gene Therapy

Diamond-Blackfan anemia (DBA) is a rare genetic disorder affecting the bone marrow's ability to produce red blood cells, leading to severe anemia and various physical abnormalities. Approximately 75% of DBA cases involve heterozygous mutations in ribosomal protein (RP) genes, classifying it as a ribosomopathy, with RPS19 being the most frequently mutated gene. Non-RP mutations, such as in GATA1, have also been identified. Current treatments include glucocorticosteroids, blood transfusions, and hematopoietic stem cell transplantation (HSCT), with HSCT being the only curative option, albeit with challenges like donor availability and immunological complications. Gene therapy, particularly using lentiviral vectors and CRISPR/Cas9 technology, emerges as a promising alternative. This review explores the potential of gene therapy, focusing on lentiviral vectors and CRISPR/Cas9 technology in combination with non-integrating lentiviral vectors, as a curative solution for DBA. It highlights the transformative advancements in the treatment landscape of DBA, offering hope for individuals affected by this condition.

Diagnosis, treatment, and surveillance of Diamond-Blackfan anaemia syndrome: international consensus statement

Diamond-Blackfan anaemia (DBA), first described over 80 years ago, is a congenital disorder of erythropoiesis with a predilection for birth defects and cancer. Despite scientific advances, this chronic, debilitating, and life-limiting disorder continues to cause a substantial physical, psychological, and financial toll on patients and their families. The highly complex medical needs of affected patients require specialised expertise and multidisciplinary care. However, gaps remain in effectively bridging scientific discoveries to clinical practice and disseminating the latest knowledge and best practices to providers. Following the publication of the first international consensus in 2008, advances in our understanding of the genetics, natural history, and clinical management of DBA have strongly supported the need for new consensus recommendations. In 2014 in Freiburg, Germany, a panel of 53 experts including clinicians, diagnosticians, and researchers from 27 countries convened. With support from patient advocates, the panel met repeatedly over subsequent years, engaging in ongoing discussions. These meetings led to the development of new consensus recommendations in 2024, replacing the previous guidelines. To account for the diverse phenotypes including presentation without anaemia, the panel agreed to adopt the term DBA syndrome. We propose new simplified diagnostic criteria, describe the genetics of DBA syndrome and its phenocopies, and introduce major changes in therapeutic standards. These changes include lowering the prednisone maintenance dose to maximum 0·3 mg/kg per day, raising the pre-transfusion haemoglobin to 9-10 g/dL independent of age, recommending early aggressive chelation, broadening indications for haematopoietic stem-cell transplantation, and recommending systematic clinical surveillance including early colorectal cancer screening. In summary, the current practice guidelines standardise the diagnostics, treatment, and long-term surveillance of patients with DBA syndrome of all ages worldwide.

Diamond-Blackfan anemia, the archetype of ribosomopathy: How distinct is it from the other constitutional ribosomopathies?

Diamond-Blackfan anemia (DBA) was the first ribosomopathy described in humans. DBA is a congenital hypoplastic anemia, characterized by macrocytic aregenerative anemia, manifesting by differentiation blockage between the BFU-e/CFU-e developmental erythroid progenitor stages. In 50 % of the DBA cases, various malformations are noted. Strikingly, for a hematological disease with a relative erythroid tropism, DBA is due to ribosomal haploinsufficiency in 24 different ribosomal protein (RP) genes. A few other genes have been described in DBA-like disorders, but they do not fit into the classical DBA phenotype (Sankaran et al., 2012; van Dooijeweert et al., 2022; Toki et al., 2018; Kim et al., 2017 [1-4]). Haploinsufficiency in a RP gene leads to defective ribosomal RNA (rRNA) maturation, which is a hallmark of DBA. However, the mechanistic understandings of the erythroid tropism defect in DBA are still to be fully defined. Erythroid defect in DBA has been recently been linked in a non-exclusive manner to a number of mechanisms that include: 1) a defect in translation, in particular for the GATA1 erythroid gene; 2) a deficit of HSP70, the GATA1 chaperone, and 3) free heme toxicity. In addition, p53 activation in response to ribosomal stress is involved in DBA pathophysiology. The DBA phenotype may thus result from the combined contributions of various actors, which may explain the heterogenous phenotypes observed in DBA patients, even within the same family.

Perspectives of current understanding and therapeutics of Diamond-Blackfan anemia

ABSTACT

Diamond-Blackfan anemia (DBA) is a rare congenital bone marrow failure disorder characterized by erythroid hypoplasia. It primarily affects infants and is often caused by heterozygous allelic variations in ribosomal protein (RP) genes. Recent studies also indicated that non-RP genes like GATA1, TSR2, are associated with DBA. P53 activation, translational dysfunction, inflammation, imbalanced globin/heme synthesis, and autophagy dysregulation were shown to contribute to disrupted erythropoiesis and impaired red blood cell production. The main therapeutic option for DBA patients is corticosteroids. However, half of these patients become non-responsive to corticosteroid therapy over prolonged treatment and have to be given blood transfusions. Hematopoietic stem cell transplantation is currently the sole curative option, however, the treatment is limited by the availability of suitable donors and the potential for serious immunological complications. Recent advances in gene therapy using lentiviral vectors have shown promise in treating RPS19-deficient DBA by promoting normal hematopoiesis. With deepening insights into the molecular framework of DBA, emerging therapies like gene therapy hold promise for providing curative solutions and advancing comprehension of the underlying disease mechanisms.

Posttransplant complications in patients with marrow failure syndromes: are we improving long-term outcomes?

Inherited bone marrow failure syndromes (IBMFS) encompass a group of rare genetic disorders characterized by bone marrow failure, non-hematologic multisystemic comorbidities, disease defining congenital anomalies, and a susceptibility to myelodysplastic syndrome, acute myeloid leukemia, and in some instances solid tumors. The most common IBMFS include Fanconi anemia, Shwachman-Diamond syndrome, Diamond-Blackfan anemia, and telomere biology disorders/ dyskeratosis congenita. Allogeneic hematopoietic stem cell transplant (HCT) is a well-established curative treatment to correct the hematological manifestations but does not halt or reverse the nonhematological complications and may hasten them. With advances in HCT and in our ability to care for patients with IBMFS, an increasing number of survivors are making it imperative to not only diagnose but also treat late effects from the pre-, peri-, and post-HCT course and complications relating to the natural history of the syndrome. As the field of HCT evolves to allow for the incorporation of alternate graft sources, for expansion of donor options to include unrelated and mismatched donors, and for use of reduced-intensity conditioning or reduced toxicity myeloablative regimens, we have yet to determine if these advances modify the disease-specific course. While long-term outcomes of these patients are often included under one umbrella, this article seeks to address disease-specific post-HCT outcomes within IBMFS.

Minimal intensity conditioning strategies for bone marrow failure: is it time for "preventative" transplants?

Hematopoietic cell transplantation (HCT) can cure blood dyscrasias and reduce the risk of hematologic cancers in patients with inherited bone marrow failure syndromes (IBMFS). However, because of its high mortality rate, HCT is generally reserved until patients with IBMFS manifest life-threatening cytopenias or myeloid malignancy, at which point outcomes are poor. Screening tests that accurately predict transformation and enable timely intervention are lacking. These unknowns and risks limit the use of HCT in patients with IBMFS, sometimes until significant disease-related sequelae have occurred. A major goal for IBMFS is to reduce cellular therapy-related complications to the point that earlier intervention can be considered before significant transfusion exposure, occurrence of comorbidities, or malignant transformation. In recent decades, disease-specific allogeneic HCT trials have yielded significant improvements in outcomes in IBMFS conditions, including Fanconi anemia and dyskeratosis congenita. This is in large part due to marked reductions in conditioning intensity to address the increased sensitivity of these patients to cytotoxic chemotherapy and radiation. The success of these approaches may also indicate an ability to leverage intrinsic fitness defects of hematopoietic stem and progenitor cells across IBMFS disorders. Now with advances in tracking somatic genetic evolution in hematopoiesis and tailored minimal intensity conditioning regimens, this question arises: is it time for preventative HCT for IBMFS?

Pediatric Bone Marrow Failure: A Broad Landscape in Need of Personalized Management

Irreversible severe bone marrow failure (BMF) is a life-threatening condition in pediatric patients. Most important causes are inherited bone marrow failure syndromes (IBMFSs) and (pre)malignant diseases, such as myelodysplastic syndrome (MDS) and (idiopathic) aplastic anemia (AA). Timely treatment is essential to prevent infections and bleeding complications and increase overall survival (OS). Allogeneic hematopoietic stem cell transplantation (HSCT) provides a cure for most types of BMF but cannot restore non-hematological defects. When using a matched sibling donor (MSD) or a matched unrelated donor (MUD), the OS after HSCT ranges between 60 and 90%. Due to the introduction of post-transplantation cyclophosphamide (PT-Cy) to prevent graft versus host disease (GVHD), alternative donor HSCT can reach similar survival rates. Although HSCT can restore ineffective hematopoiesis, it is not always used as a first-line therapy due to the severe risks associated with HSCT. Therefore, depending on the underlying cause, other treatment options might be preferred. Finally, for IBMFSs with an identified genetic etiology, gene therapy might provide a novel treatment strategy as it could bypass certain limitations of HSCT. However, gene therapy for most IBMFSs is still in its infancy. This review summarizes current clinical practices for pediatric BMF, including HSCT as well as other disease-specific treatment options.

A De Novo Frameshift Mutation in RPL5 with Classical Phenotype Abnormalities and Worsening Anemia Diagnosed in a Young Adult-A Case Report and Review of the Literature

Diamond-Blackfan anemia (DBA) is a congenital bone marrow failure syndrome associated with malformations. DBA is related to defective ribosome biogenesis, which impairs erythropoiesis, causing hyporegenerative macrocytic anemia. The disease has an autosomal dominant inheritance and is commonly diagnosed in the first year of life, requiring continuous treatment. We present the case of a young woman who, at the age of 21, developed severe symptomatic anemia. Although, due to malformations, a congenital syndrome had been suspected since birth, a confirmation diagnosis was not made until the patient was referred to our center for an evaluation of her anemia. In her neonatal medical history, she presented with anemia that required red blood cell transfusions, but afterwards remained with a stable, mild, asymptomatic anemia throughout her childhood and adolescence. Her family history was otherwise unremarkable. To explain the symptomatic anemia, vitamin deficiencies, autoimmune diseases, bleeding causes, and myeloid and lymphoid neoplasms were investigated and ruled out. A molecular investigation showed the RPL5 gene variant c.392dup, p.(Asn131Lysfs*6), confirming the diagnosis of DBA. All family members have normal blood values and none harbored the mutation. Here, we will discuss the unusual evolution of this case and revisit the literature.

Hematopoietic cell transplantation and gene therapy for Diamond-Blackfan anemia: state of the art and science

Diamond-Blackfan anemia (DBA) is one of the most common inherited causes of bone marrow failure in children. DBA typically presents with isolated erythroid hypoplasia and anemia in infants. Congenital anomalies are seen in 50% of the patients. Over time, many patients experience panhematopoietic defects resulting in immunodeficiency and multilineage hematopoietic cytopenias. Additionally, DBA is associated with increased risk of myelodysplastic syndrome, acute myeloid leukemia and solid organ cancers. As a prototypical ribosomopathy, DBA is caused by heterozygous loss-of-function mutations or deletions in over 20 ribosomal protein genes, with RPS19 being involved in 25% of patients. Corticosteroids are the only effective initial pharmacotherapy offered to transfusion-dependent patients aged 1 year or older. However, despite good initial response, only ~20-30% remain steroid-responsive while the majority of the remaining patients will require life-long red blood cell transfusions. Despite continuous chelation, iron overload and related toxicities pose a significant morbidity problem. Allogeneic hematopoietic cell transplantation (HCT) performed to completely replace the dysfunctional hematopoietic stem and progenitor cells is a curative option associated with potentially uncontrollable risks. Advances in HLA-typing, conditioning regimens, infection management, and graft-versus-host-disease prophylaxis have led to improved transplant outcomes in DBA patients, though survival is suboptimal for adolescents and adults with long transfusion-history and patients lacking well-matched donors. Additionally, many patients lack a suitable donor. To address this gap and to mitigate the risk of graft-versus-host disease, several groups are working towards developing autologous genetic therapies to provide another curative option for DBA patients across the whole age spectrum. In this review, we summarize the results of HCT studies and review advances and potential future directions in hematopoietic stem cell-based therapies for DBA.

Ovarian tissue cryopreservation in the pediatric with rare diseases- experience from China's first and the largest ovarian tissue cryobank

Background

There is limited information about the efficacy of ovarian tissue cryopreservation (OTC) in children. In the present study, we report eight patients with rare diseases who underwent OTC in China's first and largest ovarian tissue cryobank.

Procedure

Data from girls with rare diseases who underwent OTC between September 2020 and November 2022 were retrospectively analyzed. We also compared the number of cryopreserved cortex pieces, follicle number, and AMH in those with rare diseases and age-matched children with non-rare diseases who also underwent OTC in our cryobank.

Results

The median age of the children was 5.88 ± 3.52 (range 2-13) years old. Unilateral oophorectomy was undertaken via laparoscopy in all of the children. The diseases in the 8 patients were: 4 mucopolysaccharidoses (MPS I two cases, IVA two cases), 1 Diamond-Blackfan anemia (DBA), 1 Fanconi anemia (FA), 1 hyperimmunoglobulin E syndrome (HIES), 1 Niemann-Pick disease. The number of cryopreserved cortex pieces was 17.13 ± 6.36, and the follicle count per 2 mm biopsy was 447.38 ± 524.35. No significant difference in age, the count of cryopreserved cortex pieces, follicle number per 2 mm biopsy, and AMH level was seen between the 20 children with non-rare diseases and those with rare diseases.

Conclusions

The reports help practitioners counsel girls with rare diseases about fertility preservation. The demand for OTC in pediatrics will likely grow as a standard of care.

Molecular etiology of defective nuclear and mitochondrial ribosome biogenesis: Clinical phenotypes and therapy

Ribosomopathies are rare congenital disorders associated with defective ribosome biogenesis due to pathogenic variations in genes that encode proteins related to ribosome function and biogenesis. Defects in ribosome biogenesis result in a nucleolar stress response involving the TP53 tumor suppressor protein and impaired protein synthesis leading to a deregulated translational output. Despite the accepted notion that ribosomes are omnipresent and essential for all cells, most ribosomopathies show tissue-specific phenotypes affecting blood cells, hair, spleen, or skin. On the other hand, defects in mitochondrial ribosome biogenesis are associated with a range of clinical manifestations affecting more than one organ. Intriguingly, the deregulated ribosomal function is also a feature in several human malignancies with a selective upregulation or downregulation of specific ribosome components. Here, we highlight the clinical conditions associated with defective ribosome biogenesis in the nucleus and mitochondria with a description of the affected genes and the implicated pathways, along with a note on the treatment strategies currently available for these disorders.

Approach Toward Germline Predisposition Syndromes in Patients with Hematologic Malignancies

PURPOSE OF REVIEW

Hematologic malignancies were previously thought to be primarily sporadic cancers without germline predispositions. However, over the last two decades, with the widespread use of next generation sequencing (NGS), there have been several genes have been identified that carry a risk of inheriting hematologic malignancies. Identification of individuals with hereditary hematologic malignancies (HHM) involves a high index of suspicion and careful attention to family history, clinical features, and variant allele frequency on somatic NGS panels.

RECENT FINDINGS

Over the last several years, many genetic predisposition syndromes have been recognized to have unique features with both hematologic and non-hematologic co-morbidities. Multidisciplinary evaluation, including genetic counseling, is critical to optimizing diagnostic testing of individuals and at-risk family members. Prompt recognition of affected patients is imperative not only for personalized surveillance strategies but also for proper donor selection for those undergoing stem cell transplantation to avoid familial donors who also may share the same germline mutation. Herein, we describe our approach to recognizing patients suspected to carry a germline predisposition to hematologic malignancies and evaluation within a hereditary hematologic malignancies clinic (HHMC).

Variable Clinical Features in a Large Family With Diamond Blackfan Anemia Caused by a Pathogenic Missense Mutation in RPS19

Introduction: Diamond Blackfan anemia (DBA) is an autosomal dominant ribosomopathy caused predominantly by pathogenic germline variants in ribosomal protein genes. It is characterized by failure of red blood cell production, and common features include congenital malformations and cancer predisposition. Mainstays of treatment are corticosteroids, red blood cell transfusions, and hematologic stem cell transplantation (HSCT). Despite a better understanding of the genotype of DBA, the biological mechanism resulting in the clinical phenotype remains poorly understood, and wide heterogeneity can be seen even within a single family as depicted here.

Case Description: Thirty family members enrolled in the National Cancer Institute inherited bone marrow failure syndromes study were evaluated with detailed medical questionnaires and physical examinations, including 22 in the family bloodline and eight unrelated partners. Eight participants had been previously told they had DBA by clinical criteria. Targeted germline RPS19 testing was done on all family members. A pathogenic heterozygous missense mutation in RPS19 (p.R62Q, c.185G > A) was detected in ten family members, including one person previously presumed unaffected. Eight family members presented with macrocytic anemia in infancy; all of whom were responsive to prednisone. Four family members became treatment independent; however, one individual became transfusion-dependent 36 years later following an episode of pneumonia. One prednisone responsive individual electively discontinued steroid treatment, and lives with severe anemia. One prednisone responsive individual died at age 28 from a stroke. Two family members developed colorectal cancer in their fifties; one had never required treatment for anemia. None had major congenital anomalies.

Discussion: This large family with DBA demonstrates the heterogeneity of phenotypes that can be seen within the same genotype. Most family members presented with steroid-responsive anemia in infancy and subtle congenital malformations, findings consistent with recent genotype-phenotype studies of RPS DBA. However, two family members were relatively unaffected, underscoring the importance of further studies to assess modifier genes, and epigenetic and/or environmental factors which may result in normal erythropoiesis despite underlying ribosome dysfunction. This large, multigenerational family highlights the need for individualized treatment, the importance of early cancer surveillance even in individuals with clinically mild phenotypes, and the benefit of long-term follow-up to identify late complications.

Recent advances in hematopoietic cell transplantation for inherited bone marrow failure syndromes

Inherited bone marrow failure syndromes (IBMFSs) are a group of rare genetic disorders characterized by bone marrow failure with unique phenotypes and predisposition to cancer. Classical IBMFSs primarily include Fanconi anemia with impaired DNA damage repair, dyskeratosis congenita with telomere maintenance dysfunction, and Diamond-Blackfan anemia with aberrant ribosomal protein biosynthesis. Recently, comprehensive genetic analyses have been implemented for the definitive diagnosis of classic IBMFSs, and advances in molecular genetics have led to the identification of novel disorders such as AMeD and MIRAGE syndromes. Allogeneic hematopoietic cell transplantation (HCT), a promising option to overcome impaired hematopoiesis in patients with IBMFSs, does not correct nonhematological defects and may enhance the risk of secondary malignancies. Disease-specific management is necessary because IBMFSs differ in underlying defects and are associated with varying degrees of risk for clonal evolution and early or late complications after HCT. In addition, long-term follow-up is essential to detect complications related to the IBMFS or HCT. This review provides a summary of current clinical practices along with the latest data on HCT in IBMFSs.

Individualized Dosage Optimization for Myeloablative Conditioning before Unrelated Cord Blood Transplantation in a Diamond–Blackfan Anemia Patient with Germline RPL11 Mutation: A Case Study

Unrelated cord blood transplantation (CBT) for Diamond–Blackfan anemia (DBA), a systemic ribosomopathy affecting the disposition of conditioning agents, has resulted in outcomes inferior to those by transplantations from matched donors. We report the experience of the pharmacokinetics-guided myeloablative unrelated CBT in a DBA patient with a germline RPL11 mutation. The conditioning consisted of individualized dosing of fludarabine (based on weight and renal function with a target area under the curve (AUC) of 17.5 mg·h/L) and busulfan (based on therapeutic drug monitoring with a target AUC of 90 mg·h/L), as well as dosing and timing of thymoglobulin (based on body weight and pre-dose lymphocyte count to target pre-CBT AUC of 30.7 AU·day/mL and post-CBT AUC of 4.3 AU·day/mL, respectively). The pharmacokinetic measures resulted in a 27.5% reduction in busulfan and a 35% increase in fludarabine, as well as an over three-fold increase in thymoglobulin dosage with the start time changed to day-9 instead of day-2 compared to regular regimens. The transplantation resulted in rapid, complete, and sustained hematopoietic engraftment. The patient is now healthy over 3 years after CBT. A pharmacokinetics-guided individualized dosing strategy for conditioning might be a feasible option to improve the outcomes of DBA patients receiving unrelated myeloablative CBT.

Short Stature in Patients with Diamond-Blackfan Anemia: A Cross-Sectional Study

OBJECTIVE

To systematically describe the short stature of patients with Diamond-Blackfan anemia and to explore factors affecting the height development of patients with Diamond-Blackfan anemia.

STUDY DESIGN

This cross-sectional study was conducted at the Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, and the height, weight, and clinical data of 129 patients with Diamond-Blackfan anemia were collected from June 2020 to September 2020.

RESULTS

The median height-age-z score (HAZ) of children affected by Diamond-Blackfan anemia was -1.54 (-6.36-1.96). Short stature was found in 37.98% of the patients. Specific Diamond-Blackfan anemia growth curves were developed for weight, height, and body mass index, separately for male and female patients. Multivariable logistic regression models showed that female sex (aOR 4.92; 95% CI 1.29-18.71; P = .0195), underweight (aOR 10.41, 95% CI 1.41-76.98, P = .0217), cardiovascular malformations (aOR 216.65; 95% CI 3.29-14279.79; P = .0118), and RPL11(aOR 29.14; 95% CI 1.18-719.10; P = .0392) or RPS26 (aOR 53.49; 95% CI 1.40-2044.30; P = .0323) mutations were independent risk factors for short stature. In the subgroup of patients who were steroid-dependent, patients with a duration of steroid therapy over 2 years (OR 2.95; 95% CI 1.00-8.66; P = .0494) or maintenance dose of prednisone >0.1 mg/kg per day (OR 3.30; 95% CI 1.02-10.72; P = .0470) had a higher incidence of short stature.

CONCLUSIONS

Patients with Diamond-Blackfan anemia had a high prevalence of short stature. The risk of short stature increased with age and was associated with sex, underweight, congenital malformations, and RPL11 or RPS26 mutations. The duration of steroid therapy and maintenance dose of steroid was significantly associated with the incidence of short stature in steroid-dependent patients with Diamond-Blackfan anemia.

Diamond-Blackfan anemia

Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure syndrome, characterized as a rare congenital bone marrow erythroid hypoplasia (OMIM#105650). Erythroid defect in DBA results in erythroblastopenia in bone marrow as a consequence of maturation blockade between the burst forming unit-erythroid and colony forming unit-erythroid developmental stages, leading to moderate to severe usually macrocytic aregenerative (<20 × 109/L of reticulocytes) anemia. Congenital malformations localized mostly in the cephalic area and in the extremities (thumbs), as well as short stature and cardiac and urogenital tract abnormalities, are a feature of 50% of the DBA-affected patients. A significant increased risk for malignancy has been reported. DBA is due to a defect in the ribosomal RNA (rRNA) maturation as a consequence of a heterozygous mutation in 1 of the 20 ribosomal protein genes. Besides classical DBA, some DBA-like diseases have been identified. The relation between the defect in rRNA maturation and the erythroid defect in DBA has yet to be fully defined. However, recent studies have identified a role for GATA1 either due to a specific defect in its translation or due to its defective regulation by its chaperone HSP70. In addition, excess free heme-induced reactive oxygen species and apoptosis have been implicated in the DBA erythroid phenotype. Current treatment options are either regular transfusions with appropriate iron chelation or treatment with corticosteroids starting at 1 year of age. The only curative treatment for the anemia of DBA to date is bone marrow transplantation. Use of gene therapy as a therapeutic strategy is currently being explored.

Hematopoietic stem cell transplantation for classical inherited bone marrow failure syndromes: an update

INTRODUCTION

Inherited bone marrow failure syndromes (IBMFS) feature complex molecular pathophysiology resulting in ineffective hematopoiesis and increased risk of progression to myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Allogenic hematopoietic stem cell transplantation (HSCT) is the only well-established cure for the hematological manifestations of these diseases.

AREAS COVERED

In recent years, analysis of large series from international databases (mainly from the European Bone Marrow Transplantation [EBMT] database) has improved knowledge about HSCT in IBMFS. This review, following a thorough Medline search of the pertinent published studies, reports the most recent data on HSCT in IBMFS.

EXPERT OPINION

Despite the common features, IBMFS are very different in their manifestations and in the occurrence and management of HSCT complications. Thus, a 'disease-specific' HSCT using an optimized conditioning regimen based on the characteristics of the disease is essential for achieving long-term survival. The phenotypical heterogeneity associated with extramedullary abnormalities has to be carefully evaluated before HSCT because transplantation may only correct impaired hematopoiesis. HSCT may be associated with the risk of treatment-related mortality and with significant early and late morbidity. For these reasons, the benefits should be carefully weighed against the risks.

Recommendations on hematopoietic stem cell transplantation for patients with Diamond-Blackfan anemia. On behalf of the Pediatric Diseases and Severe Aplastic Anemia Working Parties of the EBMT

Diamond Blackfan anemia (DBA) is a rare congenital syndrome presenting primarily as pure red cell aplasia with constitutional abnormalities and cancer predisposition. Established treatment options are corticosteroids, regular erythrocyte transfusions with iron chelation therapy, and hematopoietic stem cell transplantation (HSCT). To date, HSCT is the only definitive curative treatment for the hematological phenotype of DBA, but there is little experience with its use. Given the rarity of the disease and its unique features, an expert panel agreed to draw up a set of recommendations on the use of HSCT in DBA to guide clinical decision-making and practice. The recommendations address indications, pretransplant patient evaluation, donor selection, stem cell sources, conditioning regimens, prophylaxis of rejection and graft versus host disease, and post-transplant follow-up.

Stem Cell Transplantation for Diamond-Blackfan Anemia. A Retrospective Study on Behalf of the Severe Aplastic Anemia Working Party of the European Blood and Marrow Transplantation Group (EBMT)

Data on stem cell transplantation (SCT) for Diamond-Blackfan Anemia (DBA) is limited. We studied patients transplanted for DBA and registered in the EBMT database. Between 1985 and 2016, 106 DBA patients (median age, 6.8 years) underwent hematopoietic stem cell transplantation from matched-sibling donors (57%), unrelated donors (36%), or other related donors (7%), using marrow (68%), peripheral blood stem cells (20%), both marrow and peripheral blood stem cells (1%), or cord blood (11%). The cumulative incidence of engraftment was 86% (80% to 93%), and neutrophil recovery and platelet recovery were achieved on day +18 (range, 16 to 20) and +36 (range, 32 to 43), respectively. Three-year overall survival and event-free survival were 84% (77% to 91%) and 81% (74% to 89%), respectively. Older patients were significantly more likely to die (hazard ratio, 1.4; 95% confidence interval, 1.06 to 1.23; P < .001). Outcomes were similar between sibling compared to unrelated-donor transplants. The incidence of acute grades II to IV of graft-versus-host disease (GVHD) was 30% (21% to 39%), and the incidence of extensive chronic GVHD was 15% (7% to 22%). This study shows that SCT may represent an alternative therapeutic option for transfusion-dependent younger patients.

Special pre- and posttransplant considerations in inherited bone marrow failure and hematopoietic malignancy predisposition syndromes

Advances in the diagnosis and treatment of inherited bone marrow failure syndromes (IBMFS) have provided insight into the complexity of these diseases. The diseases are heterogeneous and characterized by developmental abnormalities, progressive marrow failure, and predisposition to cancer. A correct diagnosis allows for appropriate treatment, genetic counseling, and cancer surveillance. The common IBMFSs are Fanconi anemia, dyskeratosis congenita, and Diamond-Blackfan anemia. Hematopoietic cell transplantation (HCT) offers curative treatment of the hematologic complications of IBMFS. Because of the systemic nature of these diseases, transplant strategies are modified to decrease immediate and late toxicities. HCT from HLA-matched related or unrelated donors offers excellent survival for young patients in aplasia. Challenges include the treatment of adults with marrow aplasia, presentation with myeloid malignancy regardless of age, and early detection or treatment of cancer. In this article, I will describe our approach and evaluation of patients transplanted with IBMFS and review most frequent complications before and after transplant.