Hematopoietic cell transplantation for Wiskott-Aldrich syndrome: advances in biology and future directions for treatment

Diagnosis and initial management of children presenting with premature loss of primary teeth associated with a systemic condition: A scoping review and development of clinical aid

BACKGROUND

Premature loss of primary teeth (PLPT) can be a rare presentation of systemic medical conditions. Premature loss of primary teeth may present a diagnostic dilemma to paediatric dentists.

AIMS

To identify systemic conditions associated with PLPT and develop a clinical aid.

DESIGN

OVID Medline, Embase and Web of Science were searched up to March 2023. Citation searching of review publications occurred. Exclusion occurred for conference abstracts, absence of PLPT and absence of English-language full text.

RESULTS

Seven hundred and ninety-one publications were identified via databases and 476 by citation searching of review articles. Removal of 390 duplicates occurred. Following the exclusion of 466 records on abstract review, 411 publications were sought for retrieval, of which 142 met inclusion criteria. Thirty-one systemic conditions were identified. For 19 conditions, only one publication was identified. The majority of publications, 91% (n = 129), were case reports or series. Most publications, 44% (n = 62), were related to hypophosphatasia, and 25% (n = 35) were related to Papillon-Lefèvre. Diagnostic features were synthesised, and a clinical aid was produced by an iterative consensus approach.

CONCLUSIONS

A diverse range of systemic diseases are associated with PLPT. Evidence quality, however, is low, with most diseases having a low number of supporting cases. This clinical aid supports paediatric dentists in differential diagnosis and onward referral.

Allogeneic hematopoietic stem cell transplantation outcome in oldest known surviving patients with Wiskott-Aldrich syndrome

Regardless of their age, adult patients with Wiskott-Aldrich syndrome should be considered for hematopoietic stem cell transplantation if clinically indicated.

Outcomes of hematopoietic stem cell gene therapy for Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is a rare X-linked disorder characterized by combined immunodeficiency, eczema, microthrombocytopenia, autoimmunity, and lymphoid malignancies. Gene therapy (GT) to modify autologous CD34+ cells is an emerging alternative treatment with advantages over standard allogeneic hematopoietic stem cell transplantation for patients who lack well-matched donors, avoiding graft-versus-host-disease. We report the outcomes of a phase 1/2 clinical trial in which 5 patients with severe WAS underwent GT using a self-inactivating lentiviral vector expressing the human WAS complementary DNA under the control of a 1.6-kB fragment of the autologous promoter after busulfan and fludarabine conditioning. All patients were alive and well with sustained multilineage vector gene marking (median follow-up: 7.6 years). Clinical improvement of eczema, infections, and bleeding diathesis was universal. Immune function was consistently improved despite subphysiologic levels of transgenic WAS protein expression. Improvements in platelet count and cytoskeletal function in myeloid cells were most prominent in patients with high vector copy number in the transduced product. Two patients with a history of autoimmunity had flares of autoimmunity after GT, despite similar percentages of WAS protein-expressing cells and gene marking to those without autoimmunity. Patients with flares of autoimmunity demonstrated poor numerical recovery of T cells and regulatory T cells (Tregs), interleukin-10-producing regulatory B cells (Bregs), and transitional B cells. Thus, recovery of the Breg compartment, along with Tregs appears to be protective against development of autoimmunity after GT. These results indicate that clinical and laboratory manifestations of WAS are improved with GT with an acceptable safety profile. This trial is registered at clinicaltrials.gov as #NCT01410825.

Correcting inborn errors of immunity: From viral mediated gene addition to gene editing

Allogeneic hematopoietic stem cell transplantation is an effective treatment to cure inborn errors of immunity. Remarkable progress has been achieved thanks to the development and optimization of effective combination of advanced conditioning regimens and use of immunoablative/suppressive agents preventing rejection as well as graft versus host disease. Despite these tremendous advances, autologous hematopoietic stem/progenitor cell therapy based on ex vivo gene addition exploiting integrating γ-retro- or lenti-viral vectors, has demonstrated to be an innovative and safe therapeutic strategy providing proof of correction without the complications of the allogeneic approach. The recent advent of targeted gene editing able to precisely correct genomic variants in an intended locus of the genome, by introducing deletions, insertions, nucleotide substitutions or introducing a corrective cassette, is emerging in the clinical setting, further extending the therapeutic armamentarium and offering a cure to inherited immune defects not approachable by conventional gene addition. In this review, we will analyze the current state-of-the art of conventional gene therapy and innovative protocols of genome editing in various primary immunodeficiencies, describing preclinical models and clinical data obtained from different trials, highlighting potential advantages and limits of gene correction.

Traffic jam within lymphocytes: A clinician's perspective

With the discovery of novel diseases and pathways, as well as a new outlook on certain existing diseases, cellular trafficking disorders attract a great deal of interest and focus. Understanding the function of genes and their products in protein and lipid synthesis, cargo sorting, packaging, and delivery has allowed us to appreciate the intricate pathophysiology of these biological processes at the molecular level and the multi-system disease manifestations of these disorders. This article focuses primarily on lymphocyte intracellular trafficking diseases from a clinician's perspective. Familial hemophagocytic lymphohistiocytosis is the prototypical disease of abnormal vesicular transport in the lymphocytes. In this review, we highlight other mechanisms involved in cellular trafficking, including membrane contact sites, autophagy, and abnormalities of cytoskeletal structures affecting the immune cell function, based on a newer classification system, along with management aspects of these conditions.

Atopy as Immune Dysregulation: Offender Genes and Targets

Allergic diseases are a heterogeneous group of disorders resulting from exaggerated type 2 inflammation. Although typically viewed as polygenic multifactorial disorders caused by the interaction of several genes with the environment, we have come to appreciate that allergic diseases can also be caused by monogenic variants affecting the immune system and the skin epithelial barrier. Through a myriad of genetic association studies and high-throughput sequencing tools, many monogenic and polygenic culprits of allergic diseases have been described. Identifying the genetic causes of atopy has shaped our understanding of how these conditions occur and how they may be treated and even prevented. Precision diagnostic tools and therapies that address the specific molecular pathways implicated in allergic inflammation provide exciting opportunities to improve our care for patients across the field of allergy and immunology. Here, we highlight offender genes implicated in polygenic and monogenic allergic diseases and list targeted therapeutic approaches that address these disrupted pathways.

Severe antenatal intraventricular hemorrhage in a newborn with WASP pathogenic variant

Wiskott-Aldrich syndrome (WAS) is a rare X-linked immunodeficiency disorder caused by abnormal expression of the Wiskott-Aldrich syndrome protein due to WAS gene mutation, usually characterized by microthrombocytopenia, eczema, hematological malignancies, recurrent infections, and a high risk of autoimmune complications. In this report, we present a family presenting with severe intrauterine cranial hemorrhage. The family has novel c.1377_1378dup (p.Pro460Hisfs*12) variant of WAS gene. The severe and early onset clinic in the family seems to be related to location of the variant on VCA domain of the WAS protein.

Clinical Features, Cancer Biology, Transplant Approach and Other Integrated Management Strategies for Wiskott-Aldrich Syndrome

Wiskott–Aldrich syndrome (WAS) is a rare X-linked recessive inborn error of immunity (IEI) first described in 1937. Classic WAS is characterized by the triad of thrombocytopenia with small platelets, recurrent infections due to combined immunodeficiency, and eczema. Hematopoietic stem cell transplantation (HSCT) was the only curative option available for five decades, with excellent outcomes reported for matched sibling donors (MSD) and matched unrelated donors (MUD). More recently, alternative donor transplants such as umbilical cord blood (UCB) and haploidentical transplant have emerged as viable options due to improvements in better graft selection, cell dosing, and effective allograft manipulation measures. Gene therapy is another potential curative option with promising results, yet currently is offered only as part of a clinical trial.

Hematopoietic Stem Cell Therapy for Wiskott-Aldrich Syndrome: Improved Outcome and Quality of Life

The Wiskott-Aldrich syndrome (WAS) is an X-linked disorder caused by mutations in the WAS gene resulting in congenital thrombocytopenia, eczema, recurrent infections and an increased incidence of autoimmune diseases and malignancies. Without curative therapies, affected patients have diminished life expectancy and reduced quality of life. Since WAS protein (WASP) is constitutively expressed only in hematopoietic stem cell-derived lineages, hematopoietic stem cell transplantation (HSCT) and gene therapy (GT) are well suited to correct the hematologic and immunologic defects. Advances in high-resolution HLA typing, new techniques to prevent GvHD allowing the use of haploidentical donors, and the introduction of reduced intensity conditioning regimens with myeloablative features have increased overall survival (OS) to over 90%. The development of GT for WAS has provided basic knowledge into vector selection and random integration of various viral vectors into the genome, with the possibility of inducing leukemogenesis. After trials and errors, inactivating lentiviral vectors carrying the WAS gene were successfully evaluated in clinical trials, demonstrating cure of the disease except for insufficient resolution of the platelet defect. Thus, 50 years of clinical evaluation, genetic exploration and extensive clinical trials, a lethal syndrome has turned into a curable disorder.

Clinical, Laboratory Features and Clinical Courses of Patients with Wiskott Aldrich Syndrome and X-linked Thrombocytopenia-A single center study

Objective: Wiskott Aldrich Syndrome is an X-linked primary immunodeficiency disorder characterized by microthrombocytopenia, severe immunodeficiency, and eczema. To define clinical-laboratory features, genetic defects (known/novel) of 23 patients of Wiskott Aldrich Syndrome/X-linked Thrombocytopenia (WAS/XLT) cohort, establish relationships between molecular defects and clinical features if present, evaluate patients who underwent hematopoietic stem cell transplantation (HSCT) and did not.Methods: Qualitative analysis from patients' hospital files and Sanger sequencing for molecular diagnosis was performed. Twenty-two WAS patients and one XLT patient were included in the study.Results: The median age of diagnosis was 15 months (2.5-172 months). The most common symptom was otitis media and all patients had microthrombocytopenia. Autoimmune findings were detected in 34.7% (8 patients) of the patients; three patients (13%) had positive anti-nuclear antibody (ANA), three patients (13%) hemolytic anemia, one patient autoimmune neutropenia, two patients vasculitis, and one patient demyelinating polyneuropathy. Nine of the 23 (39,1%) patients had HSCT with nearly 90% success. We identified 13 different mutations in our cohort; seven were novel.Conclusions: HSCT is the only curative treatment for WAS. The study confirms that early diagnosis is very important for the success of therapy, so we must increase awareness in society and physicians to keep an eye out for clues. Our study cohort and follow-up period are not sufficient to establish phenotype-genotype correlation, so a larger cohort from various centers with longer follow-up will be more decisive.

Disease Presentation, Treatment Options, and Outcomes for Myeloid Immunodeficiencies

PURPOSE OF REVIEW

Up-to-date review on various types of immunodeficiencies with a significant myeloid component including some more recently described congenital disorders.

RECENT FINDINGS

While a number of disorders have been described in the past, genetic sequencing has led to the identification of the specific disorders and clarified their pathophysiology. Advances in genetic therapies including genetic editing should provide future treatments beyond hematopoietic stem cell transplant for patients with these rare disorders. Neutrophils (or granulocytes) are a major contributor to infection surveillance and clearance, and defective neutrophils characteristically lead to pyogenic infections. Deficiency in numbers, either iatrogenic or congenital; functional defects; and/or inability to target to the sites of infection can all lead to serious morbidity and mortality; however, myeloid-based immunodeficiencies are not all the same. Having absent neutrophils, that is, neutropenia, has implications different to those of having dysfunctional neutrophils as will become evident as the various disorders are reviewed.

Successful Haploidentical Stem Cell Transplant With Posttransplant Cyclophosphamide in Wiskott-Aldrich Syndrome With Myeloablative Conditioning

Hematopoietic stem cell transplant (HSCT) is the only curative treatment modality for Wiskott-Aldrich syndrome. Haploidentical HSCT with posttransplant cyclophosphamide (PTCy) is an upcoming option in children with nonmalignant conditions. However, only few cases have been reported for Wiskott-Aldrich syndrome HSCT with PTCy approach. Here we report a 4-year-old boy, treated successfully by haploidentical HSCT with myeloablative conditioning (busulfan, fludarabine, and thiotepa) and PTCy. Posttransplant chimerism was fully donor. Of 13 cases (current case and other 12 published cases) 10 are alive and disease free after haploidentical HSCT with PTCy. Haploidentical HSCT with PTCy using myeloablative conditioning is feasible and safe.

Gene Therapies for Primary Immune Deficiencies

Gene therapy is an innovative treatment for Primary Immune Deficiencies (PIDs) that uses autologous hematopoietic stem cell transplantation to deliver stem cells with added or edited versions of the missing or malfunctioning gene that causes the PID. Initial studies of gene therapy for PIDs in the 1990-2000's used integrating murine gamma-retroviral vectors. While these studies showed clinical efficacy in many cases, especially with the administration of marrow cytoreductive conditioning before cell re-infusion, these vectors caused genotoxicity and development of leukoproliferative disorders in several patients. More recent studies used lentiviral vectors in which the enhancer elements of the long terminal repeats self-inactivate during reverse transcription ("SIN" vectors). These SIN vectors have excellent safety profiles and have not been reported to cause any clinically significant genotoxicity. Gene therapy has successfully treated several PIDs including Adenosine Deaminase Severe Combined Immunodeficiency (SCID), X-linked SCID, Artemis SCID, Wiskott-Aldrich Syndrome, X-linked Chronic Granulomatous Disease and Leukocyte Adhesion Deficiency-I. In all, gene therapy for PIDs has progressed over the recent decades to be equal or better than allogeneic HSCT in terms of efficacy and safety. Further improvements in methods should lead to more consistent and reliable efficacy from gene therapy for a growing list of PIDs.

Treatment of primary immunodeficiency with allogeneic transplant and gene therapy

The treatment of primary immunodeficiency disorders with allogeneic hematopoietic cell transplantation (HCT) has a history dating back to 1968 with the first successful transplant for a patient with severe combined immunodeficiency (SCID). The omission of conditioning for patients with SCID owing to their inability to reject allogeneic grafts and the increasing use of reduced intensity conditioning regimens often result in a state of mixed or split donor-recipient chimerism. The use of gene therapy (GT) via retroviral or lentiviral transduction of autologous CD34+ hematopoietic stem and progenitor cells is expected to correct only a portion of the hematopoietic stem cell compartment. The consequences of partial correction after either form of cellular therapy differ according to how the genetic deficiency affects immune cell development and function. Moreover, the conditioning regimen or lack thereof impacts the cell lineages at risk of partial correction. Advances in our understanding of immune reconstitution after HCT and GT for SCID, Wiskott-Aldrich syndrome, and chronic granulomatous disease are discussed.

Host and Graft Factors Impacting Infection Risk in Hematopoietic Cell Transplantation

Infection contributes significantly to morbidity and mortality in hematopoietic cell transplantation. A complex interplay of host, graft, and technical factors contributes to infectious risk in the recipient. Host factors such as age, underlying disease, and comorbidities; central venous access; and the preparative regimen contribute to mucosal disruption, organ dysfunction, and immunodeficiency before hematopoietic cell transplantation. Graft factors, including donor histocompatibility, cell source, and graft components, along with immunosuppression and graft-versus-host disease, contribute to the speed of immune reconstitution. Evaluation of these factors, plus previous and posttransplant exposure to pathogens, is necessary to best assess an individual recipient's infection risk.

Primary immunodeficiency and autoimmunity: A comprehensive review

The primary immunodeficiency diseases (PIDs) include many genetic disorders that affect different components of the innate and adaptive responses. The number of distinct genetic PIDs has increased exponentially with improved methods of detection and advanced laboratory methodology. Patients with PIDs have an increased susceptibility to infectious diseases and non-infectious complications including allergies, malignancies and autoimmune diseases (ADs), the latter being the first manifestation of PIDs in several cases. There are two types of PIDS. Monogenic immunodeficiencies due to mutations in genes involved in immunological tolerance that increase the predisposition to develop autoimmunity including polyautoimmunity, and polygenic immunodeficiencies characterized by a heterogeneous clinical presentation that can be explained by a complex pathophysiology and which may have a multifactorial etiology. The high prevalence of ADs in PIDs demonstrates the intricate relationships between the mechanisms of these two conditions. Defects in central and peripheral tolerance, including mutations in AIRE and T regulatory cells respectively, are thought to be crucial in the development of ADs in these patients. In fact, pathology that leads to PID often also impacts the Treg/Th17 balance that may ease the appearance of a proinflammatory environment, increasing the odds for the development of autoimmunity. Furthermore, the influence of chronic and recurrent infections through molecular mimicry, bystander activation and super antigens activation are supposed to be pivotal for the development of autoimmunity. These multiple mechanisms are associated with diverse clinical subphenotypes that hinders an accurate diagnosis in clinical settings, and in some cases, may delay the selection of suitable pharmacological therapies. Herein, a comprehensively appraisal of the common mechanisms among these conditions, together with clinical pearls for treatment and diagnosis is presented.

Posttransplant cyclophosphamide for haploidentical stem cell transplantation in children with Wiskott-Aldrich syndrome

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is the curative treatment for Wiskott-Aldrich syndrome (WAS). However, it is difficult to find a matched donor for patients. Therefore, haploidentical donors should be considered for patients lacking a suitable donor. Our pilot study evaluated whether HSCT with posttransplantation cyclophosphamide (PTCy) is an effective treatment for WAS.

METHODS

Haploidentical family donors were selected as donor sources for a total of five patients without a suitable donor between March 2015 and March 2017. A modified transplant protocol using PTCy (50 mg/kg/day on days +3 and +4) was performed, including busulfan (16 mg/kg), fludarabine (150 mg/m² ), and rabbit antihuman thymocyte globulin (7.5 mg/kg).

RESULTS

The median time for neutrophil recovery over 1,000 × 10³ /mm³ was 15 days (range, 12-18 days), and that for keeping platelets counts over 50,000/mm³ was 27.5 days (range, 20-35 days). The median follow-up was 2.1 years (range, 1.4-2.5 years). Two patients developed grade I acute graft-versus-host disease (GVHD), and one patient had limited chronic GVHD. All five patients are alive and independent of platelet infusion with 100% donor chimerism.

CONCLUSION

Our pilot study suggests that HSCT with modified PTCy is a safe and effective treatment for WAS, which needs further clinical practice and research.

Outcomes after Allogeneic Transplant in Patients with Wiskott-Aldrich Syndrome

/kg (range, .3 to 7.9). The median times to neutrophil and platelet engraftment were 19 days (range, 13 to 27) and 18.5 days (range, 12 to 31), respectively. The rate of overall survival was 92% with median follow-up of 67 months (range, 3 to 146). Two patients developed grade IV acute graft-versus-host disease, and 1 died on day +99. Five of 12 patient's (42%) had mixed donor chimerism (range, 12% to 85%) at day +180. None of the pretransplant patient parameters was predictive of mixed chimerism. Nonetheless, of these 5 patients, 2 had normalization of the platelet count despite the mixed chimerism, 2 had full donor chimerism after receiving a second transplant with the same donor, and 1 remains transfusion dependent awaiting a second transplant. Hence, even with a significant rate of mixed chimerism, HSCT provides substantial benefit to WAS patients, with excellent overall survival.

Gene therapy for Wiskott-Aldrich syndrome in a severely affected adult

Until recently, hematopoietic stem cell transplantation was the only curative option for Wiskott-Aldrich syndrome (WAS). The first attempts at gene therapy for WAS using a ϒ-retroviral vector improved immunological parameters substantially but were complicated by acute leukemia as a result of insertional mutagenesis in a high proportion of patients. More recently, treatment of children with a state-of-the-art self-inactivating lentiviral vector (LV-w1.6 WASp) has resulted in significant clinical benefit without inducing selection of clones harboring integrations near oncogenes. Here, we describe a case of a presplenectomized 30-year-old patient with severe WAS manifesting as cutaneous vasculitis, inflammatory arthropathy, intermittent polyclonal lymphoproliferation, and significant chronic kidney disease and requiring long-term immunosuppressive treatment. Following reduced-intensity conditioning, there was rapid engraftment and expansion of a polyclonal pool of transgene-positive functional T cells and sustained gene marking in myeloid and B-cell lineages up to 20 months of observation. The patient was able to discontinue immunosuppression and exogenous immunoglobulin support, with improvement in vasculitic disease and proinflammatory markers. Autologous gene therapy using a lentiviral vector is a viable strategy for adult WAS patients with severe chronic disease complications and for whom an allogeneic procedure could present an unacceptable risk. This trial was registered at www.clinicaltrials.gov as #NCT01347242.

Un-manipulated Haploidentical Transplant in Wiskott-Aldrich Syndrome

BACKGROUND

Allogeneic stem cell transplant is the only curative treatment for Wiskott-Aldrich syndrome.

CASE CHARACTERISTICS

18-months-old boy with no sibling, cord blood or matched unrelated donor transplant options.

OUTCOME

Doing well 7 years after haplo-identical stem cell transplantation using unmanipulated bone marrow as the stem cell source.

MESSAGE

Father as a haplo-identical donor is a feasible option.

Clinical and imaging considerations in primary immunodeficiency disorders: an update

Primary immunodeficiencies are a group of genetically determined disorders with diverse presentations. The purpose of this review is to provide a practical and brief description of a select number of these diseases and to discuss the important role the radiologist can have in making an early diagnosis and in detecting and following disease complications. The role of diagnostic imaging and informed performance and interpretation are vital in the diagnosis, surveillance and management of all primary immunodeficiency disorders.

Diagnosis and treatment of inherited thrombocytopenias

Knowledge in the field of inherited thrombocytopenias (ITs) has greatly improved over the last 15 years. Several new genes responsible for thrombocytopenia have been identified leading to the definition of novel nosographic entities and to a much better characterization of the phenotypes of these diseases. To date, ITs encompass 22 disorders caused by mutations in 24 genes and characterized by different degrees of complexity and great variability in prognosis. Making a definite diagnosis is important for setting an appropriate follow-up, choosing the best treatments and providing proper counseling. Despite the abovementioned progress, diagnosis of ITs remains difficult and these disorders are still underdiagnosed. The purpose of this review is to provide an updated guide to the diagnosis of ITs based on simple procedures. Moreover, the currently available therapeutic options for these conditions are recapitulated and discussed.

Outcomes following gene therapy in patients with severe Wiskott-Aldrich syndrome

IMPORTANCE

Wiskott-Aldrich syndrome is a rare primary immunodeficiency associated with severe microthrombocytopenia. Partially HLA antigen-matched allogeneic hematopoietic stem cell (HSC) transplantation is often curative but is associated with significant comorbidity.

OBJECTIVE

To assess the outcomes and safety of autologous HSC gene therapy in Wiskott-Aldrich syndrome.

DESIGN, SETTING, AND PARTICIPANTS

Gene-corrected autologous HSCs were infused in 7 consecutive patients with severe Wiskott-Aldrich syndrome lacking HLA antigen-matched related or unrelated HSC donors (age range, 0.8-15.5 years; mean, 7 years) following myeloablative conditioning. Patients were enrolled in France and England and treated between December 2010 and January 2014. Follow-up of patients in this intermediate analysis ranged from 9 to 42 months.

INTERVENTION

A single infusion of gene-modified CD34+ cells with an advanced lentiviral vector.

MAIN OUTCOMES AND MEASURES

Primary outcomes were improvement at 24 months in eczema, frequency and severity of infections, bleeding tendency, and autoimmunity and reduction in disease-related days of hospitalization. Secondary outcomes were improvement in immunological and hematological characteristics and evidence of safety through vector integration analysis.

RESULTS

Six of the 7 patients were alive at the time of last follow-up (mean and median follow-up, 28 months and 27 months, respectively) and showed sustained clinical benefit. One patient died 7 months after treatment of preexisting drug-resistant herpes virus infection. Eczema and susceptibility to infections resolved in all 6 patients. Autoimmunity improved in 5 of 5 patients. No severe bleeding episodes were recorded after treatment, and at last follow-up, all 6 surviving patients were free of blood product support and thrombopoietic agonists. Hospitalization days were reduced from a median of 25 days during the 2 years before treatment to a median of 0 days during the 2 years after treatment. All 6 surviving patients exhibited high-level, stable engraftment of functionally corrected lymphoid cells. The degree of myeloid cell engraftment and of platelet reconstitution correlated with the dose of gene-corrected cells administered. No evidence of vector-related toxicity was observed clinically or by molecular analysis.

CONCLUSIONS AND RELEVANCE

This study demonstrated the feasibility of the use of gene therapy in patients with Wiskott-Aldrich syndrome. Controlled trials with larger numbers of patients are necessary to assess long-term outcomes and safety.

Successful treatment of non-Hodgkin's lymphoma using R-CHOP in a patient with Wiskott-Aldrich syndrome followed by a reduced-intensity stem cell transplant

WAS is an X-linked primary immunodeficiency characterized by microthrombocytopenia, eczema, recurrent infections, and increased incidence of autoimmunity and malignancy. HSCT is the only curative treatment for WAS. Herein, we report the case of a 17-yr-old boy with WAS who received an unrelated HSCT while in complete remission of diffuse large B-cell lymphoma after chemotherapy. Pretransplant conditioning consisted of fludarabine, busulfan, and total body irradiation (4 Gy). GvHD prophylaxis consisted of tacrolimus and short-course methotrexate. Following HSCT, rapid and stable engraftment was observed. Platelet count gradually increased, and the generalized eczema improved. The patient developed grade II acute GvHD and limited chronic GvHD on days 30 and 210, respectively, which resolved with immunosuppressive treatment. Symptoms caused by the reactivation of human herpes virus-6, BK virus, and VZV were observed from days 21, 60, and 96, respectively; they were resolved after conservative treatment and acyclovir administration. No other regimen-related toxicity was observed. Complete donor bone marrow chimerism was achieved one month after transplantation. RIST is an effective therapeutic option for older children with WAS accompanied by malignant lymphoma.

Lentiviral vectors for the treatment of primary immunodeficiencies

In the last years important progress has been made in the treatment of several primary immunodeficiency disorders (PIDs) with gene therapy. Hematopoietic stem cell (HSC) gene therapy indeed represents a valid alternative to conventional transplantation when a compatible donor is not available and recent success confirmed the great potential of this approach. First clinical trials performed with gamma retroviral vectors were promising and guaranteed clinical benefits to the patients. On the other hand, the outcome of severe adverse events as the development of hematological abnormalities highlighted the necessity to develop a safer platform to deliver the therapeutic gene. Self-inactivating (SIN) lentiviral vectors (LVVs) were studied to overcome this hurdle through their preferable integration pattern into the host genome. In this review, we describe the recent advancements achieved both in vitro and at preclinical level with LVVs for the treatment of Wiskott-Aldrich syndrome (WAS), chronic granulomatous disease (CGD), ADA deficiency (ADA-SCID), Artemis deficiency, RAG1/2 deficiency, X-linked severe combined immunodeficiency (γchain deficiency, SCIDX1), X-linked lymphoproliferative disease (XLP) and immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome.

Successful allogeneic hemopoietic stem cell transplantation in a case of Wiskott-Aldrich syndrome and non-Hodgkin lymphoma

WAS is a severe X-linked recessive disorder characterized by microthrombocytopenia, eczema, and immunodeficiency. A six-yr-old boy with WAS diagnosed as B-cell NHL (Stage III) localized in the liver who underwent successful HSCT from HLA-one antigen mismatch sibling donor has been presented here. His conditioning regimen included ATG, busulfan, and fludarabine. He received 2.3 × 10(6) /kg CD 34+ stem cells and 11 × 10(8) /kg nucleated cells at day 0. Neutrophil engraftment was achieved at day +14 and platelet engraftment at day +20. He has been in CR for more than two yr after transplantation. Thus, HSCT is an effective treatment for children with WAS even after development of lymphoma.

Impact of conditioning on outcome of hematopoietic stem cell transplantation for wiskott-Aldrich syndrome

Hematopoietic stem cell transplantation (HSCT) is the treatment of choice for Wiskott-Aldrich syndrome (WAS). The aim of this retrospective study is to report the effect of the conditioning regimen and donor source on disease-free survival (DFS) in children undergoing HSCT for WAS. Fourteen children who underwent HSCT at 4 Israeli centers from 1996 to 2011 were included in this study. Five children were transplanted from matched related donors (4/5 siblings, 1/5 fully matched uncle) and other donors were used in 9 children. Six patients were conditioned with full dose busulfan/cyclophosphamide (Bu/Cy) whereas 8 patients were conditioned with other regimens. Thirteen of 14 patients (92.8%) are alive with a median follow-up of 3.4 years (range, 5 mo to 12.5 y). Nine patients (64.3%) survive with complete clinical, immunologic, and hematologic recovery. Children conditioned with full dose Bu/Cy had a 100% DFS, compared with children conditioned with other regimens, 25%±19% (P=0.022). Donor source was not associated with DFS. Graft failure was related to the use of conditioning regimens other than full dose Bu/Cy and not to the donor source. Further studies are required to determine the best conditioning regimen and optimal donor source for children with WAS.

Wiskott-Aldrich syndrome protein-deficient hematopoietic cells can be efficiently mobilized by granulocyte colony-stimulating factor

The Wiskott-Aldrich syndrome protein is an essential cytoskeleton regulator found in cells of the hematopoietic lineage and controls the motility of leukocytes. The impact of WAS gene deficiency on the mobilization of hematopoietic progenitor/stem cells in circulation has remained unexplored but information would be pertinent in the context of autologous gene therapy of Wiskott-Aldrich syndrome. The response to granulocyte-colony stimulating factor mobilization was investigated in a murine WAS knock-out model of the disease, by measuring hematologic parameters, circulation and engraftment of hematopoietic progenitor/stem cells. In the steady-state, adult WAS knock-out mice have B-cell lymphopenia, marked neutrophilia, increased counts of circulating hematopoietic progenitor cells and splenomegaly, presumably caused by the retention of hematopoietic progenitor cells due to high levels of splenic CXCL12. In spite of these anomalies, the administration of granulocyte-colony-stimulating factor mobilizes progenitor/stem cells in WAS knock-out mice to the same level and with the same kinetics as in wild-type control mice. Mobilized peripheral blood cells from WAS knock-out mice can be transduced and are able to engraft into lethally-irradiated hosts reconstituting multiple lineages of cells and providing more effective radio-protection than mobilized cells from wild-type control mice. Surprisingly, the homing and the peripheral blood recovery of B lymphocytes was influenced by the background of the host. Thus, in the absence of Wiskott-Aldrich syndrome protein, effective mobilization is achieved but partial correction may occur as a result of an abnormal hematopoietic environment.

Gene therapy for the Wiskott-Aldrich syndrome

BACKGROUND

Wiskott-Aldrich syndrome (WAS) is a rare X-linked primary immunodeficiency (PID) characterized by micro-thrombocytopenia, recurrent infections, eczema, which is associated with a high incidence of auto-immunity and lymphoreticular malignancy. One of the first diseases to be successfully treated by allogeneic hematopoietic stem cell transplantation, WAS is currently the subject of several phase I/II gene therapy trials for patients without HLA-compatible donors.

PURPOSE OF REVIEW

This article reviews the preclinical and clinical data leading to the development of gene therapy of WAS with lentiviral vectors.

RECENT FINDINGS

A recent clinical trial using a conventional gammaretroviral vector has demonstrated the proof of principle of gene therapy in WAS, but has also highlighted a common limitation of the technology. Encouraging preclinical efficacy and safety results using refined lentiviral vectors, and the development of robust clinical-grade manufacturing processes have supported the initiation of several phase I/II new studies.

SUMMARY

WAS is amenable to hematopoietic stem cell gene therapy. New trials using lentiviral vectors are expected to improve efficacy and safety profiles. Beyond proof of principle, ongoing international efforts to coordinate trials of gene therapy for the WAS may also provide a model for the expedited development of new treatments for other rare diseases.

What To Do When You Suspect an Inherited Platelet Disorder

Inherited platelet disorders (IPDs) comprise a heterogenous group of diseases that include defects in platelet function and disordered megakaryopoiesis. Some IPDs overlap as both defects in function and thrombopoiesis, resulting in both altered aggregation and/or secretion and thrombocytopenia. This review examines the key features of the presentation of IPDs in children and adults and presents a diagnostic algorithm for the evaluation of these patients. In addition, recent advances in our understanding of the pathophysiology of platelet disorders are addressed, with attention given to some of the novel genetic associations. Finally, treatment options and future therapies are briefly discussed.

Long-term outcome and lineage-specific chimerism in 194 patients with Wiskott-Aldrich syndrome treated by hematopoietic cell transplantation in the period 1980-2009: an international collaborative study

In this retrospective collaborative study, we have analyzed long-term outcome and donor cell engraftment in 194 patients with Wiskott-Aldrich syndrome (WAS) who have been treated by hematopoietic cell transplantation (HCT) in the period 1980- 2009. Overall survival was 84.0% and was even higher (89.1% 5-year survival) for those who received HCT since the year 2000, reflecting recent improvement of outcome after transplantation from mismatched family donors and for patients who received HCT from an unrelated donor at older than 5 years. Patients who went to transplantation in better clinical conditions had a lower rate of post-HCT complications. Retrospective analysis of lineage-specific donor cell engraftment showed that stable full donor chimerism was attained by 72.3% of the patients who survived for at least 1 year after HCT. Mixed chimerism was associated with an increased risk of incomplete reconstitution of lymphocyte count and post-HCT autoimmunity, and myeloid donor cell chimerism < 50% was associated with persistent thrombocytopenia. These observations indicate continuous improvement of outcome after HCT for WAS and may have important implications for the development of novel protocols aiming to obtain full correction of the disease and reduce post-HCT complications.

Otitis media in children with congenital immunodeficiencies

Otitis media represents one of the most common infections in childhood. Within the first 3 years of life, up to 80% of children experience at least one episode of otitis media. It is often resolved with supportive therapies and consequently not considered a worrisome problem. However, it may be an early manifestation of a severe underlying disease. Primary immunodeficiencies are rare congenital defects of the immune system that often remain unrecognized, or diagnosis can be delayed, sometimes resulting in fatal consequences for the child. Patients suffer from recurrent, prolonged, and/or unusual infections leading to local sequelae, failure to thrive, developmental delays, and systemic infections with severe courses. This review provides a brief insight into primary immunodeficiencies and an overview of leading findings that should result in further evaluation of the immune system in cases of otitis media. A stepwise diagnostic approach is proposed to facilitate early and accurate diagnosis and, consequently, effective and timely therapy to improve the patient's outcome and quality of life.