Hematopoietic stem cell transplantation in severe congenital neutropenia: experience of the French SCN register

Genetic backgrounds and clinical characteristics of congenital neutropenias in Israel

BACKGROUND

Congenital neutropenias are characterized by severe infections and a high risk of myeloid transformation; the causative genes vary across ethnicities. The Israeli population is characterized by an ethnically diverse population with a high rate of consanguinity.

OBJECTIVE

To evaluate the clinical and genetic spectrum of congenital neutropenias in Israel.

METHODS

We included individuals with congenital neutropenias listed in the Israeli Inherited Bone Marrow Failure Registry. Sanger sequencing was performed for ELANE or G6PC3, and patients with wild-type ELANE/G6PC3 were referred for next-generation sequencing.

RESULTS

Sixty-five patients with neutropenia were included. Of 51 patients with severe congenital neutropenia, 34 were genetically diagnosed, most commonly with variants in ELANE (15 patients). Nine patients had biallelic variants in G6PC3, all of consanguineous Muslim Arab origin. Other genes involved were SRP54, JAGN1, TAZ, and SLC37A4. Seven patients had cyclic neutropenia, all with pathogenic variants in ELANE, and seven had Shwachman-Diamond syndrome caused by biallelic SBDS variants. Eight patients (12%) developed myeloid transformation, including six patients with an unknown underlying genetic cause. Nineteen (29%) patients underwent hematopoietic stem cell transplantation, mostly due to insufficient response to treatment with granulocyte-colony stimulating factor or due to myeloid transformation.

CONCLUSIONS

The genetic spectrum of congenital neutropenias in Israel is characterized by a high prevalence of G6PC3 variants and an absence of HAX1 mutations. Similar to other registries, for 26% of the patients, a molecular diagnosis was not achieved. However, myeloid transformation was common in this group, emphasizing the need for close follow-up.

Reduced toxicity matched sibling bone marrow transplant results in excellent outcomes for severe congenital neutropenia

Severe congenital neutropenia (SCN) is caused by germline mutations, most commonly in ELANE, impacting neutrophil maturation and leading to high risk of life-threatening infections. Most patients with ELANE-mutant SCN can achieve safe neutrophil counts with chronic Granulocyte-Colony Stimulating Factor (G-CSF). However, up to 10% of patients have neutropenia refractory to G-CSF and require allogeneic stem cell transplant. Traditional conditioning for these patients includes busulfan and cyclophosphamide which is associated with significant toxicities. We present five patients with SCN without myeloid malignancy transplanted using a reduced toxicity regimen of busulfan, fludarabine and thymoglobulin. 5 pediatric patients with SCN underwent matched sibling donor bone marrow transplant (MSD-BMT) between 2014-2022 on or per CHP14BT057 (NCT02928991), a prospective, single center trial testing elimination of cyclophosphamide from conditioning in pediatric patients with single lineage inherited BMF syndromes. All patients had MSDs and no evidence of MDS. Conditioning consisted of PK-adjusted busulfan, fludarabine, and thymoglobulin, with calcineurin inhibitor and mycophenolate mofetil GVHD prophylaxis. With median follow-up of 48.4 months, overall and event-free survival were 100%. There was no acute GVHD and one instance of chronic limited GVHD. Patients exhibited >95% donor myeloid chimerism at 5 years post-BMT. Two patients experienced CMV reactivation without end-organ disease, and no other viral reactivation or significant infections occurred. MSD-BMT with reduced toxicity myeloablation for SCN provides excellent outcomes while minimizing toxicity. These data suggest that busulfan, fludarabine, and ATG can be considered an efficacious, low-toxicity standard of care regimen for patients with SCN undergoing MSD-BMT.

Diagnosis and management of neutropenia in children: The approach of the Study Group on Neutropenia and Marrow Failure Syndromes of the Pediatric Italian Hemato-Oncology Association (Associazione Italiana Emato-Oncologia Pediatrica - AIEOP)

Neutropenia refers to a group of diseases characterized by a reduction in neutrophil levels below the recommended age threshold. The present study aimed to review the diagnosis and management of neutropenia, including a diagnostic toolkit and candidate underlying genes. This study also aimed to review the progress toward the definition of autoimmune and idiopathic neutropenia rising in infancy or in late childhood but without remission, and provide suggestions for efficient diagnostics, including indications for the bone marrow and genetic testing. The management and treatment protocols for common and unique presentations are also reviewed, providing evidence tailored to a single patient.

Outcomes for patients with severe chronic neutropenia treated with granulocyte colony-stimulating factor

Severe chronic neutropenia (SCN), defined as blood neutrophils < 0.5 x 109/L for more than 3 months, is an uncommon hematological condition associated with recurrent and severe bacterial infections. After short-term clinical trials showed the benefits of granulocyte colony-stimulating factor (G-CSF) treatment for SCN, the Severe Chronic Neutropenia International Registry (SCNIR) opened to determine the long-term benefits and safety of this treatment. This report summarizes findings from more than 16 000 patient-years of prospective observations for patients with congenital and acquired SCN. We observed that adverse outcomes depend on the underlying etiology. MDS and AML occur infrequently and largely in patients with congenital neutropenias. Having cyclic or chronic autoimmune/idiopathic neutropenia portends a favorable prognosis. A few patients with idiopathic neutropenia evolve to develop lymphoid malignancies, but they do not appear to be at increased risk of myeloid malignancies, even with very long-term G-CSF therapy. Progression to systemic autoimmune diseases, bone marrow failure, aplastic anemia, or non-myeloid malignancies are not expected consequences of SCN or treatment with G-CSF.

Hematopoietic stem cell transplantation for inherited bone marrow failure syndromes: alternative donor and disease-specific conditioning regimen with unmanipulated grafts

Objective: The outcomes of alternative donor hematopoietic stem cell transplantation (HSCT) with unmanipulated grafts for Inherited bone marrow failure syndromes (IBMFS) are discouraging. Our study is to demonstrate that IBMFS with disease-specific characteristics requires a tailored conditioning regimens to enhance engraftment and reduce regimen related toxicities. Methods: We retrospectively analyzed 42 patients diagnosed with IBMFS and transplanted with an alternative donor graft at our center from November 2012 to August 2018. Twenty-seven patients had Fanconi anemia (FA), 7 had dyskeratosis congenita (DC), and 8 had severe congenital neutropenia (SCN). Patients received ex-vivo unmanipulated alternative donor grafts from a matched unrelated donor (MUD) (n = 22), haploidentical donor (HID) (n = 17) and unrelated cord blood donor (UCBD) (n = 3). FA and DC patient subgroups received reduce intensified conditioning (RIC), while SCN patients received a myeloablative conditioning (MAC) regimen. Results: The median follow-up time for the surviving patients was 38 months (range: 9-63 months). The failure-free survival (FFS) for entire cohort was 76.1%, and was 72.4%, 100% and 56.2% for patients with FA, DC and SCN, respectively. There were no primary graft failures. The cumulative incidence of aGVHD at day 100 was 48.1%. The cumulative incidence of cGVHD at 1 and 3 years was 35.0% and 69.3%, respectively. Conclusion: HSCT using alternative donors with unmanipulated grafts and disease-specific conditioning regimens for IBMFS patients shows promising survival.

Neutrophil Elastase Defects in Congenital Neutropenia

Severe congenital neutropenia (SCN) is a rare hematological condition with heterogenous genetic background. Neutrophil elastase (NE) encoded by ELANE gene is mutated in over half of the SCN cases. The role of NE defects in myelocytes maturation arrest in bone marrow is widely investigated; however, the mechanism underlying this phenomenon has still remained unclear. In this review, we sum up the studies exploring mechanisms of neutrophil deficiency, biological role of NE in neutrophil and the effects of ELANE mutation and neutropenia pathogenesis. We also explain the hypotheses presented so far and summarize options of neutropenia therapy.

Management of a Patient With Congenital Biallelic CSF3R Mutation With GM-CSF

Severe Congenital Neutropenia (SCN) is a rare inherited disease characterized by an absolute neutrophil count (ANC) lower than 500/μL. Genetic heterogeneity and biallelic CSF3R mutation has rarely been identified as an underlying genetic defect in SCN. The majority of SCN patients respond to granulocyte colony stimulating factor treatment; however, in patients with inherited CSF3R mutation, ANC cannot generally be increased with granulocyte colony stimulating factor treatment. In such cases, granulocyte macrophage colony stimulating factor presents as an effective treatment option. Herein, we report a case of a 5-year-old SCN girl with homozygous c610-611 del ins AG (p.Q204R) mutation in the CSF3R gene, who was successfully treated with granulocyte macrophage colony stimulating factor.

HSCT may lower leukemia risk in ELANE neutropenia: a before-after study from the French Severe Congenital Neutropenia Registry

ELANE neutropenia is associated with myelodysplasia and acute leukemia (MDS–AL), and severe infections. Because the MDS–AL risk has also been shown to be associated with exposure to GCSF, since 2005, in France, patients receiving high daily GCSF doses (>15 μg/kg/day) are eligible for HSCT, in addition to classic indications (MDS–AL or GCSF refractoriness). We analyzed the effect of this policy. Among 144 prospectively followed ELANE-neutropenia patients enrolled in the French Severe Congenital Neutropenia Registry, we defined two groups according to period: “before 2005” for those born before 2005 and followed until 31/12/2004 (1588 person-years); and “after 2005” comprised of those born after 2005 or born before 2005 but followed after 2005 until 31/03/2019 (1327 person-years). Sixteen of our cohort patients underwent HSCT (14 long-term survivors) and six developed MDS–ALs. Six leukemic transformations occurred in the before-2005 group and none after 2005 (respective frequencies 3.8 × 10^–3 vs. 0; P < 0.01), while four HSCTs were done before 2005 and 12 since 2005 (respective HSCT rates increased 2.5 × 10^–3 vs. 9 × 10^–3; P < 0.01). Our results support early HSCT for patients with ELANE mutations who received high GCSF doses, as it might lower the risk of leukemic transformation.

Elastase inhibitors as potential therapies for ELANE-associated neutropenia

Mutations in ELANE, the gene for neutrophil elastase (NE), a protease expressed early in neutrophil development, are the most frequent cause of cyclic (CyN) and severe congenital neutropenia (SCN). We hypothesized that inhibitors of NE, acting either by directly inhibiting enzymatic activity or as chaperones for the mutant protein, might be effective as therapy for CyN and SCN. We investigated β-lactam-based inhibitors of human NE (Merck Research Laboratories, Kenilworth, NJ, USA), focusing on 1 inhibitor called MK0339, a potent, orally absorbed agent that had been tested in clinical trials and shown to have a favorable safety profile. Because fresh, primary bone marrow cells are rarely available in sufficient quantities for research studies, we used 3 cellular models: patient-derived, induced pluripotent stem cells (iPSCs); HL60 cells transiently expressing mutant NE; and HL60 cells with regulated expression of the mutant enzyme. In all 3 models, the cells expressing the mutant enzyme had reduced survival as measured with annexin V and FACS. Coincubation with the inhibitors, particularly MK0339, promoted cell survival and increased formation of mature neutrophils. These studies suggest that cell-permeable inhibitors of neutrophil elastase show promise as novel therapies for ELANE-associated neutropenia.

Severe congenital neutropenias

Severe congenital neutropenias are a heterogeneous group of rare haematological diseases characterized by impaired maturation of neutrophil granulocytes. Patients with severe congenital neutropenia are prone to recurrent, often life-threatening infections beginning in their first months of life. The most frequent pathogenic defects are autosomal dominant mutations in ELANE, which encodes neutrophil elastase, and autosomal recessive mutations in HAX1, whose product contributes to the activation of the granulocyte colony-stimulating factor (G-CSF) signalling pathway. The pathophysiological mechanisms of these conditions are the object of extensive research and are not fully understood. Furthermore, severe congenital neutropenias may predispose to myelodysplastic syndromes or acute myeloid leukaemia. Molecular events in the malignant progression include acquired mutations in CSF3R (encoding G-CSF receptor) and subsequently in other leukaemia-associated genes (such as RUNX1) in a majority of patients. Diagnosis is based on clinical manifestations, blood neutrophil count, bone marrow examination and genetic and immunological analyses. Daily subcutaneous G-CSF administration is the treatment of choice and leads to a substantial increase in blood neutrophil count, reduction of infections and drastic improvement of quality of life. Haematopoietic stem cell transplantation is the alternative treatment. Regular clinical assessments (including yearly bone marrow examinations) to monitor treatment course and detect chromosomal abnormalities (for example, monosomy 7 and trisomy 21) as well as somatic pre-leukaemic mutations are recommended.

Allogeneic Transplant in ELANE and MEFV Mutation Positive Severe Cyclic Neutropenia: Review of Prognostic Factors for Secondary Severe Events

Objective and Importance. Cyclic neutropenia (CyN) is a rare autosomal dominant inherited disorder due to the mutation ELANE primarily affecting bone marrow stem cells and is characterized by recurrent neutropenia every 2 to 4 weeks. Symptoms vary from benign to severe, including death. Postulations on the cause of wide spectrum in symptom presentation include the possibility of other genetic mutations, such as MEFV. Recommended treatment for CyN is G-CSF to keep ANC higher to minimize risk of infection. Case. A 25-year-old male diagnosed with CyN, on G-CSF but worsening quality of life. Pretransplant investigations revealed ELANE mutation positive severe CyN along with familial Mediterranean fever (MEFV) mutation. Intervention. Bone marrow transplantation as treatment for dual mutation (ELANE and MEFV mutation) positive severe CyN. Conclusion. BMT may be considered as an alternative treatment for severe CyN in patients who are refractory to G-CSF. It is postulated that in our patient the combined mutations (CyN and MEFV) may have contributed to the severity of this individual's symptoms. We suggest CyN patients who present with severe symptoms have evaluation with ELANE mutation testing, Periodic Fever Syndromes Panel, and routine marrow assessment with FISH, conventional cytogenetics, and morphological evaluation for MDS/AML.

Allogeneic hematopoietic stem cell transplantation for inherited bone marrow failure syndromes

Inherited bone marrow failure (IBMF) syndromes are a heterogeneous group of rare hematological disorders characterized by the impairment of hematopoiesis, which harbor specific clinical presentations and pathogenic mechanisms. Some of these syndromes may progress through clonal evolution, myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Most prominent are failures of DNA repair such as Fanconi Anemia and much rarer failure of ribosomal apparatus, e.g., Diamond Blackfan Anemia or of telomere elongation such as dyskeratosis congenita. In these congenital disorders, hematopoietic stem cell transplantation (HSCT) is often a consideration. However, HSCT will not correct the underlying disease and possible co-existing extra-medullary (multi)-organ defects, but will improve BMF. Indications as well as transplantation characteristics are most of the time controversial in this setting because of the rarity of reported cases. The present paper proposes a short overview of current practices.

Stem cell transplantation in severe congenital neutropenia: an analysis from the European Society for Blood and Marrow Transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment of severe congenital neutropenia (SCN), but data on outcome are scarce. We report on the outcome of 136 SCN patients who underwent HSCT between 1990 and 2012 in European and Middle East centers. The 3-year overall survival (OS) was 82%, and transplant-related mortality (TRM) was 17%. In multivariate analysis, transplants performed under the age of 10 years, in recent years, and from HLA-matched related or unrelated donors were associated with a significantly better OS. Frequency of graft failure was 10%. Cumulative incidence (day +90) of acute graft-versus-host disease (GVHD) grade 2-4 was 21%. In multivariate analysis, HLA-matched related donor and prophylaxis with cyclosporine A and methotrexate were associated with lower occurrence of acute GVHD. Cumulative incidence (1 year) of chronic GVHD was 20%. No secondary malignancies occurred after a median follow-up of 4.6 years. These data show that the outcome of HSCT for SCN from HLA-matched donors, performed in recent years, in patients younger than 10 years is acceptable. Nevertheless, given the TRM, a careful selection of HSCT candidates should be undertaken.

Recommendations on hematopoietic stem cell transplantation for inherited bone marrow failure syndromes

Allogeneic hematopoietic stem cell transplantation (HSCT) offers the potential to cure patients with an inherited bone marrow failure syndrome (IBMFS). However, the procedure involves the risk of treatment-related mortality and may be associated with significant early and late morbidity. For these reasons, the benefits should be carefully weighed against the risks. IBMFS are rare, whereas case reports and small series in the literature illustrate highly heterogeneous practices in terms of indications for HSCT, timing, stem cell source and conditioning regimens. A consensus meeting was therefore held in Vienna in September 2012 on behalf of the European Group for Blood and Marrow Transplantation to discuss HSCT in the setting of IBMFS. This report summarizes the recommendations from this expert panel, including indications for HSCT, timing, stem cell source and conditioning regimen.

Hematopoietic Cell Transplantation Using Reduced-Intensity Conditioning Is Successful in Children with Hematologic Cytopenias of Genetic Origin

Genetically derived hematologic cytopenias are a rare heterogeneous group of disorders. Allogeneic hematopoietic cell transplantation (HCT) is curative but offset by organ toxicities from the preparative regimen, graft rejection, graft-versus-host disease (GVHD), or mortality. Because of these possibilities, consideration of HCT can be delayed, especially in the unrelated donor setting. We report a prospective multicenter trial of reduced-intensity conditioning (RIC) with alemtuzumab, fludarabine, and melphalan and HCT in 11 children with marrow failure of genetic origin (excluding Fanconi anemia) using the best available donor source (82% from unrelated donors). The median age at transplantation was 23 months (range, 2 months to 14 years). The median times to neutrophil (>500 × 10(6)/L) and platelet (>50 × 10(9)/L) engraftment were 13 (range, 12 to 24) and 30 (range, 7 to 55) days, respectively. The day +100 probability of grade II to IV acute GVHD and the 1-year probability of limited and extensive GVHD were 9% and 27%, respectively. The probability of 5-year overall and event-free survival was 82%; 9 patients were alive with normal blood counts at last follow-up and all were successfully off systemic immunosuppression. In patients with genetically derived severe hematologic cytopenias, allogeneic HCT with this RIC regimen was successful in achieving a cure. This experience supports consideration of HCT early in such patients even in the absence of suitable related donors.

Clinical spectrum and long-term follow-up of 14 cases with G6PC3 mutations from the French Severe Congenital Neutropenia Registry

Background

The purpose of this study was to describe the natural history of severe congenital neutropenia (SCN) in 14 patients with G6PC3 mutations and enrolled in the French SCN registry.

Methods

Among 605 patients included in the French SCN registry, we identified 8 pedigrees that included 14 patients with autosomal recessive G6PC3 mutations.

Results

Median age at the last visit was 22.4 years. All patients had developed various comordibities, including prominent veins (n = 12), cardiac malformations (n = 12), intellectual disability (n = 7), and myopathic syndrome with recurrent painful cramps (n = 1). Three patients developed Crohn’s disease, and five had chronic diarrhea with steatorrhea. Neutropenia was profound (<0.5 × 10⁹/l) in almost all cases at diagnosis and could marginally fluctuate. The bone marrow smears exhibited mild late-stage granulopoeitic defects. One patient developed myelodysplasia followed by acute myelogenous leukemia with translocation (18, 21) at age 14 years, cured by chemotherapy and hematopoietic stem cell transplantation. Four deaths occurred, including one from sepsis at age 5, one from pulmonary late-stage insufficiency at age 19, and two from sudden death, both at age 30 years. A new homozygous mutation (c.249G > A /p.Trp83*) was detected in one pedigree.

Conclusions

Severe congenital neutropenia with autosomal recessive G6PC3 mutations is associated with considerable clinical heterogeneity. This series includes the first described case of malignancy in this neutropenia.

[SFGM-TC recommendation on indications for allogeneic stem cell transplantation in children with congenital neutropenia]

In this report, we address the issue of allogeneic stem cell transplantation in children with congenital neutropenia. Constitutional disorders with neutropenia are exceptional. Treatment and prevention of severe infections are a major concern in the management of chronic neutropenia. These disorders, especially Kostmann's disease and Shwachman-Bodian-Diamond syndrome, are associated with an increased risk of leukemia. The role of allogeneic stem cell transplantation in these patients is still unclear. In an effort to harmonize clinical practices between different French transplantation centers, the French Society of Bone Marrow Transplantation and Cell Therapy (SFGM-TC) set up the fourth annual series of workshops which brought together practitioners from all member centers and took place in September 2013 in Lille.

Neurological findings and genetic alterations in patients with Kostmann syndrome and HAX1 mutations

OBJECTIVES

To describe the clinical profile and the prevalence of severe congenital neutropenia (SCN) and HAX1 mutations, so-called Kostmann syndrome, in France.

STUDY DESIGN

Two pedigrees were identified from the French registry.

RESULTS

The study included five subjects (three males), which represent 0.7% of the 759 SCN cases registered in France. The age at diagnosis was 0.3 years (range: 0.1-1.2 years) and the median age at the last follow-up was 7.3 years (range: 1.2-17.8 years). A novel large homozygous deletion of the HAX1 gene (exons 2-5) was found in one pedigree; while, a homozygous frameshift mutation was identified in exon 3 (c.430dupG, p.Val144fs) in the second pedigree. Severe bacterial infections were observed in four patients, including two cases of sepsis, one case of pancolitis, a lung abscess, and recurrent cellulitis and stomatitis. During routine follow-up, the median neutrophil value was 0.16 × 10(9)/L, associated with monocytosis (2 × 10(9)/L). Bone marrow (BM) smears revealed a decrease of the granulocytic lineage with no mature myeloid cells above the myelocytes. One patient died at age 2 from neurological complications, while two other patients, including one who underwent a hematopoietic stem cell transplantation (HSCT) at age 5, are living with very severe neurological retardation.

CONCLUSIONS

SCN with HAX1 mutations, is a rare sub type of congenital neutropenia, mostly observed in population from Sweden and Asia minor, associating frequently neurological retardation, when the mutations involved the B isoform of the protein.

Neutropenia in primary immunodeficiency

PURPOSE OF REVIEW

Neutropenia is a feature of several primary immunodeficiency diseases (PIDDs). Because of the diverse pathophysiologies of the PIDDs and the rarity of each disorder, data are often lacking, leading to the necessity of empiric treatment. Recent developments in the understanding of neutropenia in several of the PIDDs make a review of the data timely.

RECENT FINDINGS

The category of severe congenital neutropenia continues to expand. Mutations in G6PC3 have been identified as the cause of neutropenia in a minority of previously molecularly undefined cases. Recent advances have broadened our understanding of the pathophysiology and the clinical expression of this disorder. A possible function of the C16orf57 gene has been hypothesized that may explain the clinical overlap between Clerucuzio-type poikiloderma with neutropenia and other marrow diseases. Plerixafor has been shown to be a potentially useful treatment in the warts, hypogammaglobulinemia, infection, and myelokathexis syndrome. Investigations of patients with adenosine deaminase deficient severe combined immunodeficiency have identified neutropenia, and particularly susceptibility to myelotoxins, as a feature of this disorder. Granulocyte-colony stimulating factor is the treatment of choice for neutropenia in PIDD, whereas hematopoietic cell transplantation is the only curative option.

SUMMARY

The number of PIDDs associated with neutropenia has increased, as has our understanding of the range of phenotypes. Additional data and hypotheses have been generated helping to explain the diversity of presentations of neutropenia in PIDDs.

Extended spectrum of human glucose-6-phosphatase catalytic subunit 3 deficiency: novel genotypes and phenotypic variability in severe congenital neutropenia

OBJECTIVE

To delineate the phenotypic and molecular spectrum of patients with a syndromic variant of severe congenital neutropenia (SCN) due to mutations in the gene encoding glucose-6-phosphatase catalytic subunit 3 (G6PC3).

STUDY DESIGN

Patients with syndromic SCN were characterized for associated malformations and referred to us for G6PC3 mutational analysis.

RESULTS

In a cohort of 31 patients with syndromic SCN, we identified 16 patients with G6PC3 deficiency including 11 patients with novel biallelic mutations. We show that nonhematologic features of G6PC3 deficiency are good predictive indicators for mutations in G6PC3. Additionally, we demonstrate genetic variability in this disease and define novel features such as growth hormone deficiency, genital malformations, disrupted bone remodeling, and abnormalities of the integument. G6PC3 mutations may be associated with hydronephrosis or facial dysmorphism. The risk of transition to myelodysplastic syndrome/acute myeloid leukemia may be lower than in other genetically defined SCN subgroups.

CONCLUSIONS

The phenotypic and molecular spectrum in G6PC3 deficiency is wider than previously appreciated. The risk of transition to myelodysplastic syndrome or acute myeloid leukemia may be lower in G6PC3 deficiency compared with other subgroups of SCN.

Hematopoietic stem cell transplantation for severe congenital neutropenia

PURPOSE OF REVIEW

Hematopoietic stem cell transplantation (HCT) is the only curative option for patients with severe congenital neutropenia (SCN). Transplant success is dependent on identifying at-risk patients and proceeding to transplant before the development of severe infections or malignant transformation. This review focuses on recent advancements in risk stratification of SCN patients, indications for HCT, and review of published transplant studies.

RECENT FINDINGS

Patients with poor neutrophil response despite high doses of granulocyte colony-stimulating factor (G-CSF) are at greatest risk for malignant transformation. Other studies demonstrate elevated risk with mutations in the G-CSF receptor gene and a specific mutation in the ELANE gene. These patients are at high-risk of sepsis or leukemia development and should proceed to transplant with best available donor. As recent published studies demonstrate, HCT is highly successful in patients without leukemia and, therefore, may be considered in selected low-risk patients given the life-long risk of malignancy and infection.

SUMMARY

The decision whether to proceed to HCT in healthy patients maintained on G-CSF is difficult. As transplant-related mortality continues to decrease, the role of transplant in SCN is likely to expand to more patients.

Congenital and acquired neutropenias consensus guidelines on therapy and follow-up in childhood from the Neutropenia Committee of the Marrow Failure Syndrome Group of the AIEOP (Associazione Italiana Emato-Oncologia Pediatrica)

The management of congenital and acquired neutropenias presents some differences according to the type of the disease. Treatment with recombinant human granulocyte-colony stimulating factor (G-CSF) is not standardized and scanty data are available on the best schedule to apply. The frequency and the type of longitudinal controls in patients affected with neutropenias are not usually discussed in the literature. The Neutropenia Committee of the Marrow Failure Syndrome Group (MFSG) of the Associazione Italiana di Emato-Oncologia Pediatrica (AIEOP) elaborated this document following design and methodology formerly approved by the AIEOP board. The panel of experts reviewed the literature on the topic and participated in a conference producing a document that includes recommendations on neutropenia treatment and timing of follow-up.

[Severe congenital neutropenia: analysis of clinical features, diagnostic methods, treatment and long-term outcome]

INTRODUCTION

Severe congenital neutropenia (SCN), a heterogeneous condition with onset at early ages, is characterised by primary myelopoiesis failure with an absolute neutrophil count (ANC) < 0.5 x10(9)/L, severe infections and risk of leukaemic transformation.

OBJECTIVE

The aim of the study was to ascertain the long term outcome of patients with SCN.

MATERIAL AND METHODS

The clinical features, diagnostic methods, treatment and outcome of 11 patients with SCN were analysed.

RESULTS

The median age at diagnosis was 4 months (range: 3 days-12 years). The primary clinical manifestation was severe infection. Median ANC at diagnosis: 0.2 x 10(9)/L (range: 0-0.37). Bone marrow aspirate showed maturation arrest at promyelocyte stage in all cases. Genetic studies revealed 3 mutations, two in ELA-2 gene and 1 in G6PC3 gene, showing a correlation between genotype and phenotype. Granulocyte Colony Stimulating Factor (G-CSF) was the first-line treatment in 9 patients; six of whom showed a good response at doses between 5 and 15 μg/kg/day for 3-7 days/week. The remaining 3 patients failed to respond to G-CSF and allogeneic stem cell transplantation (SCT) was indicated. Furthermore, SCT was the treatment of choice in two cases. Median follow-up of the cohort was 5 years (range: 1-10 years) with 100% survival and no cases of leukaemic transformation.

CONCLUSIONS

We conclude that genetic study is useful for establishing a correlation between genotype and phenotype. The treatment of choice for SCN is G-CSF to which 2/3 of patients should respond; while SCT is reserved for cases of poor response or those evolving to myelodysplastic syndrome (MDS) or leukaemia; thus close follow-up of this condition is essential.

Congenital neutropenia: diagnosis, molecular bases and patient management

The term congenital neutropenia encompasses a family of neutropenic disorders, both permanent and intermittent, severe (<0.5 G/l) or mild (between 0.5-1.5 G/l), which may also affect other organ systems such as the pancreas, central nervous system, heart, muscle and skin. Neutropenia can lead to life-threatening pyogenic infections, acute gingivostomatitis and chronic parodontal disease, and each successive infection may leave permanent sequelae. The risk of infection is roughly inversely proportional to the circulating polymorphonuclear neutrophil count and is particularly high at counts below 0.2 G/l.When neutropenia is detected, an attempt should be made to establish the etiology, distinguishing between acquired forms (the most frequent, including post viral neutropenia and auto immune neutropenia) and congenital forms that may either be isolated or part of a complex genetic disease.Except for ethnic neutropenia, which is a frequent but mild congenital form, probably with polygenic inheritance, all other forms of congenital neutropenia are extremely rare and have monogenic inheritance, which may be X-linked or autosomal, recessive or dominant.About half the forms of congenital neutropenia with no extra-hematopoietic manifestations and normal adaptive immunity are due to neutrophil elastase (ELANE) mutations. Some patients have severe permanent neutropenia and frequent infections early in life, while others have mild intermittent neutropenia.Congenital neutropenia may also be associated with a wide range of organ dysfunctions, as for example in Shwachman-Diamond syndrome (associated with pancreatic insufficiency) and glycogen storage disease type Ib (associated with a glycogen storage syndrome). So far, the molecular bases of 12 neutropenic disorders have been identified.Treatment of severe chronic neutropenia should focus on prevention of infections. It includes antimicrobial prophylaxis, generally with trimethoprim-sulfamethoxazole, and also granulocyte-colony-stimulating factor (G-CSF). G-CSF has considerably improved these patients' outlook. It is usually well tolerated, but potential adverse effects include thrombocytopenia, glomerulonephritis, vasculitis and osteoporosis. Long-term treatment with G-CSF, especially at high doses, augments the spontaneous risk of leukemia in patients with congenital neutropenia.

Hematopoietic stem cell transplantation in severe congenital neutropenia

BACKGROUND

Severe congenital neutropenia (SCN) is an immunodeficiency characterized by disturbed myelopoiesis and an absolute neutrophil count (ANC) <0.5 × 10(9)/L. SCN is also a premalignant condition; a significant proportion of patients develop myelodysplastic syndrome or leukemia (MDS/L). Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment for SCN.

PROCEDURE

Since 2004, eight HSCT have been performed in seven patients at our center. The indications were transformation to MDS/L (n = 2), granulocyte colony-stimulating factor receptor (CSF3R) mutation(s) (n = 2), granulocyte colony-stimulating factor (G-CSF) resistance (n = 2), and at the patient's own request (n = 1).

RESULTS

The mean age at transplantation was 13 years (2.8-28 years) (mean follow-up 32 months, range 21-60). Three patients harbored ELANE mutations, three HAX1 mutations, and in one patient no causative mutation was identified. Two of the ELANE mutations were novel mutations. Three patients initially received myeloablative conditioning and four had reduced intensity conditioning (RIC). Three grafts were from HLA-identical siblings, three from matched unrelated donors and two were cord blood units. Engraftment occurred in all patients. Two of seven (29%) patients died; both had MDS/L and both were among the three that underwent myeloablative conditioning. One patient has chronic GVHD 2 years post-transplant.

CONCLUSIONS

The role of HSCT should be explored further in patients with SCN. In particular, the influence of the conditioning regime needs to be evaluated in a larger cohort of patients.

Transplantation for congenital bone marrow failure syndromes

Congenital bone marrow failure syndromes (BMFSs) are relatively rare disorders characterized by aberrant development in one or more hematopoietic lineages. Genetic alterations have now been identified in most of these disorders although the exact role of the molecular defects has yet to be elucidated. Most of these diseases are successfully managed with supportive care, however, treatment refractoriness and disease progression-often involving malignant transformation-may necessitate curative treatment with hematopoietic stem cell transplantation. Due to the underlying molecular defects, the outcome of transplantation for BMFS may be dramatically different than those associated with transplantation for more common diseases, including leukemia. Given recent improvements in survival and molecular diagnosis of bone marrow failure syndrome patients presenting at adult ages without physical stigmata, it is important for both pediatric and adult hematologists to be aware of the possible diagnosis of BMF syndromes and the unique approaches required in treating such patients.

Outcomes after related and unrelated umbilical cord blood transplantation for hereditary bone marrow failure syndromes other than Fanconi anemia

BACKGROUND

Allogeneic stem cell transplantation is the only curative option for patients with hereditary bone marrow failure syndromes. Umbilical cord blood is an alternative source of stem cells for allogeneic transplantation.

DESIGN AND METHODS

This multicenter, retrospective study is based on data reported to the Eurocord Registry about patients with hereditary bone marrow failure syndrome who underwent umbilical cord blood transplantation.

RESULTS

Sixty-four patients with hereditary bone marrow failure syndromes were transplanted from related (n = 20) or unrelated donors (n = 44). Diagnoses were Diamond-Blackfan anemia (21 patients), congenital amegakaryocytic thrombocytopenia (16 patients), dyskeratosis congenita (8 patients), Shwachman-Diamond syndrome (2 patients), severe congenital neutropenia (16 patients) and unclassified (1 patient). In the group of patients who received grafts from related donors, all patients but one received an HLA-matched sibling transplant. The median number of total nucleated cells infused was 5 × 10⁷/kg. The cumulative incidence of neutrophil recovery at 60 days was 95%. Two patients had grade II-IV acute graft-versus-host disease, while the 2-year cumulative incidence of chronic graft-versus-host disease was 11%. The 3-year overall survival rate was 95%. In the group of patients who received grafts from unrelated donors, 86% had HLA-mismatched grafts and three received two umbilical cord blood units. The median number of total nucleated cells infused was 6.1 × 10⁷/kg. The cumulative incidence of neutrophil recovery at day 60 in this group was 55%. The 100-day cumulative incidence of grade II-IV acute graft-versus-host disease was 24%, while the 2-year cumulative incidence of chronic graft-versus-host disease was 53%. The 3-year overall survival rate was 61%; better overall survival was associated with age less than 5 years (P = 0.01) and 6.1 × 10⁷/kg or more total nucleated cells infused (P = 0.05).

CONCLUSIONS

In patients with hereditary bone marrow failure syndromes, related umbilical cord blood transplantation is associated with excellent outcomes while increasing cell dose and better HLA matching might provide better results in unrelated umbilical cord blood transplantation.

Hematopoietic stem cell transplantation in patients with severe congenital neutropenia: an analysis of 18 Japanese cases

We studied the outcome of allogeneic HSCT in patients with SCN. Between 1989 and 2005, 18 patients with SCN in Japan received HSCT for reasons other than malignant transformation, i.e., because of the lack of or a partial response to treatment with r-HuG-CSF. The median age of the patients at the first HSCT was three and a half yr (range 0.2-16.7 yr). Nine patients received stem cells from an HLA-identical sibling donor and nine from an alternative donor. Twelve and six patients received myeloablative and non-myeloablative conditioning regimens, respectively. Engraftment occurred at the first HSCT in 12 patients, four patients received a second HSCT for graft failure, and two patients died. The cause of death was renal failure and graft failure at the first and second HSCT, respectively. The cumulative incidence of grade II-IV acute GVHD and TRM at the first transplantation was 11% and 5.6%, respectively. Of our patients, 16 are alive and in complete remission, with a median follow-up of six and a half yr. Our results suggest that HSCT is beneficial for patients with SCN refractory to r-HuG-CSF treatment.

Resolving a genetic paradox throughout preimplantation genetic diagnosis for autosomal dominant severe congenital neutropenia

OBJECTIVE

Severe congenital neutropenia is an inherited disease characterized by low peripheral blood neutrophils, amenable to bone marrow transplantation. Genetic analysis in the family here described detected a ELA2 splice-site mutation in the affected child and also in his asymptomatic father. The parents requested preimplantation genetic diagnosis (PGD), coupled with HLA matching, to obtain a suitable bone marrow donor for the affected child.

METHODS

A PGD protocol was developed, based on multiplex nested PCR for direct analysis of the ELA2 mutation, flanking polymorphic markers and HLA typing.

RESULTS

The amplification efficiency of the mutation was > 90% in single leukocytes from the affected child but only 67% in the father. Analysis of single haploid sperm cells from the father demonstrated three different sperm-cell populations: (1) sperm cells harboring the ELA2 mutation on the 'affected' haplotype, (2) sperm cells without the ELA2 mutation on the 'normal' haplotype, and (3) sperm cells without the ELA2 mutation on the 'affected' haplotype.

CONCLUSION

These data demonstrate that the ELA2 mutation in the father occurred de novo during his embryonic development, resulting in somatic as well as germ-line mosaicism. This conclusion was also taken into consideration when PGD was performed.

Eponym. Kostmann disease

Rolf Kostmann (1909-1982) was a Swedish pediatrician and army doctor. He was the first to describe an inherited form of chronic neutropenia in childhood. In 1956, Kostmann published his article "Infantile genetic agranulocytosis" in Acta Paediatrica. "Infantile agranulocytosis," as Rolf Kostmann named this hereditary syndrome, has been known for more than half a century, yet the underlying genetic mutations have remained unknown for many decades. Fifty years later, homozygous mutations in the gene encoding the mitochondrial protein HCLS1-associated X1 were found in affected members of the original Kostmann pedigree. Therefore, the eponym "Kostmann disease" best fits this specific mutation and mode of inheritance. The identification of genetic cause now allows the analysis of genotype-phenotype correlations. After the development of recombinant human granulocyte colony-stimulating factor (G-CSF), the prognosis and quality of life improved dramatically. Hematopoietic stem cell transplantation remains the only currently available treatment for refractory cases to G-CSF and patients who have transformed into leukemia.

Bone marrow transplantation for inherited bone marrow failure syndromes

The inherited bone marrow failure (BMF) syndromes are characterized by impaired hematopoiesis and cancer predisposition. Most inherited BMF syndromes are also associated with a range of congenital anomalies. Progress in improving the outcomes for children with inherited BMF syndromes has been limited by the rarity of these disorders, as well as disease-specific genetic, molecular, cellular, and clinical characteristics that increase the risks of complications associated with hematopoietic stem cell transplantation (HSCT). As a result, the ability to develop innovative transplant approaches to circumvent these problems has been limited. Recent progress has been made, as best evidenced in studies adding fludarabine to the preparative regimen for children undergoing unrelated donor HSCT for Fanconi anemia. The rarity of these diseases coupled with the far more likely incremental improvements that will result from ongoing research will require prospective international clinical trials to improve the outcome for these children.

Bone marrow transplantation for primary immunodeficiency diseases

Advances in immunology have led to a breathtaking expansion of recognized primary immunodeficiency diseases (PID) with over 120 disease-related genes identified. In North America alone more than 1000 children have received allogeneic blood or marrow transplant over the past 30 years, with the majority surviving long term. This review presents results and highlights challenges and notable advances, including novel less toxic conditioning regimens, to transplant the more common and severe forms of PID. HLA-matched sibling donors remain the ideal option, however, advances in living donor unrelated HSCT and banked umbilical cord blood grafts provide hope for all children with severe PID.

Unrelated cord blood transplantation in children with severe congenital neutropenia

SCN is an inherited hematological disorder with severe neutropenia and recurrent infections. Although there are some reports that recombinant rhG-CSF improves clinical outcome, allogeneic HSCT appears to be the only curative treatment for these patients. We report here two children with SCN successfully treated by CBT from unrelated donors. They were refractory to rhG-CSF treatment and have no identical family donor. Bu + CY were given as conditioning. Case 1 and Case 2 received 6/6 and 5/6 HLA-matched unrelated umbilical cord blood, respectively. The number of infused nucleated cells was 6, 18 x 10(7)/kg and CD34(+) cell number was 3, 74 x 10(5)/kg in Case 1. Those cell numbers were 8, 8 x 10(7)/kg and 5, 34 x 10(5)/kg for Case 2, respectively. Neutrophil/platelet engraftments were 45/49 days in Case 1 and 24/36 days in Case 2. Grade II cutaneous acute GVHD was seen in Case 2 that was treated successfully with prednisolone. Both patients are well with normal hematological findings and full donor chimerism for post-transplant 20 and 24 months, respectively. We conclude that UCB can be considered as a safe source of stem cell in patients with SCN who need urgent HSCT.

Unrelated donor and HLA-identical sibling haematopoietic stem cell transplantation cure chronic granulomatous disease with good long-term outcome and growth

Chronic granulomatous disease (CGD) causes recurrent infection and inflammatory disease. Despite antimicrobial prophylaxis, patients experience frequent hospitalisations and 50% mortality by 30 years. Haematopoietic stem cell transplantation (HSCT) can cure CGD with resolution of infection and colitis. This study reports the survival and long-term outcome in 20 conditioned patients treated between 1998 and 2007, using 10 matched sibling (MSD) and 10 unrelated donors (URD). Age at HSCT, graft-versus-host disease (GvHD), growth, and outcome were analysed. Fourteen had > or = 1 invasive infection, 10 had colitis and seven had growth failure before HSCT. Median age at transplantation was 75 months (range 15 months-21 years). Eighteen (90%) were alive 4-117 months (median 61) after HSCT with normal neutrophil function. Two died from disseminated fungal infection. Two experienced significant chronic GvHD, with continuing sequelae in 1. Colitis resolved within 8 weeks of HSCT. Mean weight and height for age Z scores on recovery from HSCT rose significantly (P < 0.001). HSCT with MSD or URD gave excellent engraftment and survival, remission of colitis and catch-up growth, with low incidence of significant GvHD. Transplant-associated complications were restricted to those with pre-existing infection or inflammation, supporting the argument for early HSCT for more CGD patients with a well matched donor.

Unrelated cord blood transplantation for severe congenital neutropenia: report of two cases with very different transplant courses

SCN is characterized by neutropenia, life-threatening infections, and progression to myelodysplastic syndrome/acute myelogenous leukemia. The only curative option is SCT, but few reports using UCB as a stem cell source exist. Here, we report two SCN patients transplanted with UCB. Patient 1 was transplanted at seven yr of age due to increasingly large injections of G-CSF (>100 microg/kg/day) and the risk of developing leukemia. He engrafted promptly and is clinically well and immune reconstituted >2 yr post-transplant. Patient 2 underwent UCB SCT at nine months of age for recurrent severe infections, despite high doses of G-CSF. He rejected his first graft, having 100% host cells on day +35, and immediately underwent a second UCB SCT. He engrafted but experienced late graft rejection six months after the second transplant. He received a third UCB SCT following a more immunosuppressive conditioning regimen. His course was complicated by HHV-6 viremia and gut GVHD, but he is now clinically well and has 99% donor engraftment >20 months post-transplant. We conclude that UCB is an acceptable stem cell source for SCN patients, but conditioning must be adequately immunosuppressive to ensure engraftment in patients without prior chemotherapy.

Reduced-intensity conditioning is effective and safe for transplantation of patients with Shwachman-Diamond syndrome

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only potentially curative treatment for the BM dysfunction seen in patients with Shwachman-Diamond syndrome (SDS). Historically, these patients have fared poorly with intensive conditioning regimens with increased regimen-related toxicity especially involving the heart and lungs. We report our institutional experience with a reduced-intensity-conditioning protocol in seven patients with SDS and BM aplasia or myelodysplastic syndrome/AML. The preparative regimen consisted of Campath-1H, fludarabine and melphalan. Four patients received matched related marrow and three received unrelated stem cells (two PBSCs and one marrow). All but one was 8 of 8 allele HLA matched. All patients established 100% donor-derived hematopoiesis. No patient in this cohort developed grades III-IV GVHD. One patient had grade II skin GVHD that responded to systemic corticosteroids and one had grade I skin GVHD, treated with topical corticosteroids. Two out of seven patients developed bacterial infections in the early post transplant period. Viral infections were seen in four out of seven patients and were successfully treated with appropriate antiviral therapy. All patients are currently alive. These data indicate that HSCT with reduced-intensity conditioning is feasible in patients with SDS and associated with excellent donor cell engraftment and modest morbidity.

Lymphadenopathy as the primary manifestation of malignant transformation in two patients with severe congenital neutropenia

We present the cases of two patients with severe congenital neutropenia (SCN) who both developed generalized adenopathy. Although both had recent histories that placed infection high on the differential of causes for the adenopathy, biopsies demonstrated acute myeloid leukemia (AML) as the etiology. The risk of malignant transformation in SCN is known to be significantly elevated, and these cases illustrate the need for physicians of such patients to keep myelodysplastic syndrome (MDS) and AML high on the differential when patients manifest atypical symptoms.

Non-myeloablative transplantation for severe congenital neutropenia

Severe Congenital Neutropenia is a rare condition characterized by a very low neutrophil count, which pre-disposes the affected child to recurrent bacterial infections. Treatment with granulocyte colony stimulating factor (G-CSF) has dramatically improved the prognosis of these children; but in patients who have become G-CSF refractory, hematopoeitic stem cell transplant is still the only effective curative treatment. We describe a patient who was unresponsive to escalating doses of G-CSF and underwent a successful reduced intensity conditioning, matched unrelated donor allograft resulting in cure.

[Granulopoeisis and leukemogenesis: lessons from congenital neutropenia]

Congenital neutropenia are extremely rare diseases, defined by a permanent or cyclic decrease of blood neutrophils. Molecular basis of several congenital neutropenia has been recently determined, involving gene coding for the neutrophil elastase gene (ELA2), GFI1, WAS protein and mitochondrial HAX1 protein. These mutations, dominant (ELA2, GFI1), X-linked (WAS) and autosomal recessive (HAX1), result in instability of the contents of the granules- particularly the neutrophil elastase- or in abnormalities of the cytoskeleton, and possibly, in an increased apoptosis. ELA2 mutations resulting both in profound and permanent neutropenia, and in cyclic--pseudo sinusoidal--neutropenia lead to consider that time pattern is very close in the two apparently distinct phenotypes. This observation suggests that temporal variations of neutrophils could be represented by non linear functions. Congenital neutropenia, specifically ELA2 mutated, are also characterized by a high rate of leukemia (about 15% at 20 years of age). Leukemia risk does not appear to be related to an oncogenic effect of ELA2 mutations, but much likely to the deepness of the neutropenia, and the intensity of G-CSF therapy.

Stem cell transplantation in primary immunodeficiencies

PURPOSE OF REVIEW

To review indications and outcomes of haematopoietic stem cell transplantation in primary immunodeficiencies, in light of recent advances in the field.

RECENT FINDINGS

Remarkable improvements in the outcome of haematopoietic stem cell transplantation in primary immunodeficiencies have recently been reported. This is a result of the successful use of alternative donors and more effective strategies to prevent and treat complications. These advances have now permitted the indications for haematopoietic stem cell transplantation to be extended in primary immunodeficiencies.

SUMMARY

The optimal results of haematopoietic stem cell transplantation in primary immunodeficiencies have long been obtained with related human leukocyte antigen-identical donors, an option limited to a minority of patients. Transplantation from mismatched related donors has been used with good results mainly in infants with severe combined immune deficiency, but has been associated with significantly delayed or incomplete immune reconstitution. Recent data indicate that transplantation from matched unrelated donors and cord blood transplantation represent valid alternatives, which can be used in all forms of severe primary immunodeficiencies. This, along with careful monitoring of infections, coupled with preemptive treatment, has resulted in a significant improvement in the outcome of haematopoietic stem cell transplantation for severe forms of primary immunodeficiencies.

The investigation and management of chronic neutropenia in children

Unravelling the cause of a neutropenia poses a complex diagnostic challenge. The differential diagnosis ranges from life threatening disease to transient benign causes of little clinical significance. This review offers a practical guide to investigating the neutropenic child, and highlights features that merit specialist referral. Therapeutic options, the role of long term follow up, and the complications of severe chronic neutropenia are considered.