Three-dimensional tissue-engineered human skeletal muscle model of Pompe disease.

In Pompe disease, the deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA) causes skeletal and cardiac muscle weakness, respiratory failure, and premature death. While enzyme replacement therapy using recombinant human GAA (rhGAA) can significantly improve patient outcomes, detailed disease mechanisms and incomplete therapeutic effects require further studies. Here we report a three-dimensional primary human skeletal muscle ("myobundle") model of infantile-onset Pompe disease (IOPD) that recapitulates hallmark pathological features including reduced GAA enzyme activity, elevated glycogen content and lysosome abundance, and increased sensitivity of muscle contractile function to metabolic stress. In vitro treatment of IOPD myobundles with rhGAA or adeno-associated virus (AAV)-mediated hGAA expression yields increased GAA activity and robust glycogen clearance, but no improvements in stress-induced functional deficits. We also apply RNA sequencing analysis to the quadriceps of untreated and AAV-treated GAA-/- mice and wild-type controls to establish a Pompe disease-specific transcriptional signature and reveal novel disease pathways. The mouse-derived signature is enriched in the transcriptomic profile of IOPD vs. healthy myobundles and partially reversed by in vitro rhGAA treatment, further confirming the utility of the human myobundle model for studies of Pompe disease and therapy.

Expansion of immature, nucleated red blood cells by transient low-dose methotrexate immune tolerance induction in mice.

Biological treatments such as enzyme-replacement therapies (ERT) can generate anti-drug antibodies (ADA), which may reduce drug efficacy and impact patient safety and consequently led to research to mitigate ADA responses. Transient low-dose methotrexate (TLD-MTX) as a prophylactic ITI regimen, when administered concurrently with ERT, induces long-lived reduction of ADA to recombinant human alglucosidase alfa (rhGAA) in mice. In current clinical practice, a prophylactic ITI protocol that includes TLD-MTX, rituximab and intravenous immunoglobulin (optional), successfully induced lasting control of ADA to rhGAA in high-risk, cross-reactive immunological material (CRIM)-negative infantile-onset Pompe disease (IOPD) patients. More recently, evaluation of TLD-MTX demonstrated benefit in CRIM-positive IOPD patients. To more clearly understand the mechanism for the effectiveness of TLD-MTX, non-targeted transcriptional and proteomic screens were conducted and revealed up-regulation of erythropoiesis signatures. Confirmatory studies showed transiently larger spleens by weight, increased spleen cellularity and that following an initial reduction of mature red blood cells (RBCs) in the bone marrow and blood, a significant expansion of Ter-119+ CD71+ immature RBCs was observed in spleen and blood of mice. Histology sections revealed increased nucleated cells, including hematopoietic precursors, in the splenic red pulp of these mice. This study demonstrated that TLD-MTX induced a transient reduction of mature RBCs in the blood and immature RBCs in the bone marrow followed by significant enrichment of immature, nucleated RBCs in the spleen and blood during the time of immune tolerance induction, which suggested modulation of erythropoiesis may be associated with the induction of immune tolerance to rhGAA.

Safety of Intradiaphragmatic Delivery of Adeno-Associated Virus-Mediated Alpha-Glucosidase (rAAV1-CMV-hGAA) Gene Therapy in Children Affected by Pompe Disease.

A first-in-human trial of diaphragmatic gene therapy (AAV1-CMV-GAA) to treat respiratory and neural dysfunction in early-onset Pompe disease was conducted. The primary objective of this study was to assess the safety of rAAV1-CMV-hGAA vector delivered to the diaphragm muscle of Pompe disease subjects with ventilatory insufficiency. Safety was assessed by measurement of change in serum chemistries and hematology, urinalysis, and immune response to GAA and AAV, as well as change in level of health. The data demonstrate that the AAV treatment was safe and there were no adverse events related to the study agent. Adverse events related to the study procedure were observed in subjects with lower baseline neuromuscular function. All adverse events were resolved before the end of the study, except for one severe adverse event determined not to be related to either the study agent or the study procedure. In addition, an anti-capsid and anti-transgene antibody response was observed in all subjects who received rAAV1-CMV-hGAA, except for subjects who received concomitant immunomodulation to manage reaction to enzyme replacement therapy, as per their standard of care. This observation is significant for future gene therapy studies and serves to establish a clinically relevant approach to blocking immune responses to both the AAV capsid protein and transgene product.

Enzyme replacement therapy for infantile-onset Pompe disease.

BACKGROUND: Infantile-onset Pompe disease is a rare and progressive autosomal-recessive disorder caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). Current treatment involves enzyme replacement therapy (with recombinant human alglucosidase alfa) and symptomatic therapies (e.g. to control secretions). Children who are cross-reactive immunological material (CRIM)-negative require immunomodulation prior to commencing enzyme replacement therapy.Enzyme replacement therapy was developed as the most promising therapeutic approach for Pompe disease; however, the evidence is lacking, especially regarding the optimal dose and dose frequency. OBJECTIVES: To assess the effectiveness, safety and appropriate dose regimen of enzyme replacement therapy for treating infantile-onset Pompe disease. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Inborn Errors of Metabolism Trials Register, which is compiled from electronic database searches and handsearching of journals and conference abstract books. We also searched the Cochrane Central Register of Controlled Trials (CENTRAL), Embase (Ovid), PubMed and LILACS, and CBM, CNKI, VIP, and WANFANG for literature published in Chinese. In addition, we searched three online registers: WHO International Clinical Trials Registry Platform ClinicalTrials.gov, and www.genzymeclinicalresearch.com. We also searched the reference lists of relevant articles and reviews.Date of last search of the Group's Inborn Errors of Metabolism Trials Register: 24 November 2016. SELECTION CRITERIA: Randomized and quasi-randomized controlled trials of enzyme replacement therapy in children with infantile-onset Pompe disease. DATA COLLECTION AND ANALYSIS: Two authors independently selected relevant trials, assessed the risk of bias and extracted data. We contacted investigators to obtain important missing information. MAIN RESULTS: We found no trials comparing the effectiveness and safety of enzyme replacement therapy to another intervention, no intervention or placebo.We found one trial (18 participants) that fulfilled the selection criteria, comparing different doses of alglucosidase alfa. The trial provided low-quality evidence (this was a small trial, there were no numerical results available by dose group, random sequence generation and allocation concealment were unclear, and there was a lack of blinding). The duration of alglucosidase alfa treatment ranged from 52 weeks (the length of the original study) to up to three years (including the extended phase of the trial), with a median duration of treatment being 2.3 years.The trial only reported that clinical responses including cardiac function and motor development, as well as the proportion of children that were free of invasive ventilation, were similar in the 20 mg/kg every two weeks and the 40 mg/kg every two weeks groups (low-quality evidence). Long-term alglucosidase alfa treatment markedly extended survival as well as ventilation-free survival and improved cardiomyopathy (low-quality evidence). In relation to the number of children experiencing one or more infusion-related events, there was no significant difference between dose groups, risk ratio 0.83 (95% confidence interval 0.40 to 1.76) (low-quality of evidence). However, of note, at 52 weeks, five children in the 20 mg/kg every two weeks dose group experienced a total of 41 mild or moderate (none severe) infusion-related events and the six children in the 40 mg/kg every two weeks dose group experienced a total of 123 infusion-related events. By the end of the extended phase of the trial, five children in the 20 mg/kg every two weeks dose group experienced a total of 47 infusion-related events and the six children in the 40 mg/kg every two weeks dose group experienced a total of 177 infusion-related events. The trial was supported by the Genzyme Corporation. AUTHORS' CONCLUSIONS: The search found no trials comparing the effectiveness and safety of enzyme replacement therapy to another intervention, no intervention or placebo. One small randomized controlled trial provided no robust evidence for which dosing schedule of alglucosidase alfa was more effective to treat infantile-onset Pompe disease. It is not deemed ethical to proceed with new placebo-controlled trials, therefore a randomized controlled trial with a large sample size comparing different dosing schedules of enzyme replacement therapy is needed. The main clinical outcomes (i.e. cardiac function, invasive ventilation, survival, motor development, adverse events (e.g. the development of antibodies)) should be standardized when evaluated and reported.

Quantification of muscle pathology in infantile Pompe disease.

The effects of enzyme replacement therapy (ERT) in infantile Pompe disease are variable, necessitating the identification of biomarkers to assess the severity of disease and response to ERT. The aims of this study were to investigate whether quantification of muscle pathology in infantile Pompe disease prior to and during ERT is feasible at the light microscope, and to develop a score that summarizes the degree of muscle pathology in a comprehensive manner from PAS-stained resin sections alone. We, therefore, determined glycogen load, extent of muscle fibre disruption, and amount of autophagic vacuoles in resin-embedded muscle biopsy specimens from 11 infantile Pompe patients and 2 with early childhood phenotype by quantitative methods, correlated the findings with ultrastructural analyses, compared PAS-stained resin sections with conventional PAS-stained cryosections, and related the quantified degree of muscle damage from infantile patients to the effects of ERT. Comparison of electron and light microscopic findings demonstrated that important alterations of skeletal muscle morphology can also be depicted by examining PAS stained resin sections. Infantile patients with good response to ERT had lower muscle pathology score values prior to and during ERT than those with moderate and poor response, but the number of tissue samples available for evaluation was limited. These findings suggest that quantification of muscle pathology by analysing PAS stained resin sections is in principle feasible and useful to monitor disease progression and therapy response. These results have to be validated by investigating a larger group of patients.

Prospective exploratory muscle biopsy, imaging, and functional assessment in patients with late-onset Pompe disease treated with alglucosidase alfa: The EMBASSY Study.

BACKGROUND: Late-onset Pompe disease is characterized by progressive skeletal myopathy followed by respiratory muscle weakness, typically leading to loss of ambulation and respiratory failure. In this population, enzyme replacement therapy (ERT) with alglucosidase alfa has been shown to stabilize respiratory function and improve mobility and muscle strength. Muscle pathology and glycogen clearance from skeletal muscle in treatment-naïve adults after ERT have not been extensively examined. METHODS: This exploratory, open-label, multicenter study evaluated glycogen clearance in muscle tissue samples collected pre- and post- alglucosidase alfa treatment in treatment-naïve adults with late-onset Pompe disease. The primary endpoint was the quantitative reduction in percent tissue area occupied by glycogen in muscle biopsies from baseline to 6months. Secondary endpoints included qualitative histologic assessment of tissue glycogen distribution, secondary pathology changes, assessment of magnetic resonance images (MRIs) for intact muscle and fatty replacement, and functional assessments. RESULTS: Sixteen patients completed the study. After 6months of ERT, the percent tissue area occupied by glycogen in quadriceps and deltoid muscles decreased in 10 and 8 patients, respectively. No changes were detected on MRI from baseline to 6months. A majority of patients showed improvements on functional assessments after 6months of treatment. All treatment-related adverse events were mild or moderate. CONCLUSIONS: This exploratory study provides novel insights into the histopathologic effects of ERT in late-onset Pompe disease patients. Ultrastructural examination of muscle biopsies demonstrated reduced lysosomal glycogen after ERT. Findings are consistent with stabilization of disease by ERT in treatment-naïve patients with late-onset Pompe disease.

Seguridad y eficacia de alglucosidasa alfa en el tratamiento de pacientes con enfermedad de pompe de inicio tardío / Safety and efficacy of alglucosidase alfa in the treatment of patients with late-onset pompe disease

INTRODUCCIÓN: Antecedentes: El presente informe expone la evaluación del medicamento alglucosidasa alfa (AA) respecto a su uso en pacientes con enfermedad de Pompe de inicio tardío (EPIT). Aspectos generales: La enfermedad de Pompe, clasificada también como enfermedad por depósito del glucógeno tipo II, es un trastorno de herencia autosómica recesiva que causa deficiencia de la enzima denominada alfa-1,4-glucosidasa ácida (GAA). La deficiencia de la enzima GAA conduce a la acumulación de glucógeno en los lisosomas y en el citoplasma, resultando en la destrucción de los tejidos, principalmente del musculo esquelético y cardiaco. Tecnología Sanitaria de Interés: Alglucosidasa Alfa: La AA es una forma recombinante de la enzima GAA, el cual es requerido para la división del glucógeno. La AA se une a los receptores de manosa 6-fosfato en la superficie de las células, es internalizado y transportado a los lisosomas donde es activado para aumentar la división del glucógeno. METODOLOGÍA: Estratégia de Busqueda: Se realizó una búsqueda de la literatura con respecto a la eficacia y seguridad de AA como terapia de reemplazo enzimático en pacientes con EPIT, en las bases de datos de OVID MEDLINE y TRIPDATABASE. También se hizo una búsqueda adicional en www.clinicaltrials.gov, para poder identificar ensayos en desarrollo o no publicados. \r\nAdicionalmente, se hizo una búsqueda dentro de la información generada por grupos que realizan revisiones sistemáticas, evaluación de tecnologías sanitarias y guías de práctica clínica, tales como The Cochrane Library y The National Institute for Health and Care Excellence (NICE). RESULTADOS: Sinopsis de la Evidencia: Se realizó la búsqueda bibliográfica y de evidencia científica para el sustento del uso de AA en el tratamiento de pacientes con EPIT. A continuación se detallan los resultados de la búsqueda según tipo de publicación. Guías Clínicas: la búsqueda identificó dos guías sobre la EPIT. Ambas guías fueron desarrolladas por el grupo de expertos de la enfermedad de Pompe en España, para el diagnóstico, seguimiento y manejo de la EPIT; y la más actual, para el seguimiento de la EPIT; Evaluaciones de tecnología sanitaria: \r\nse identificó una evaluación de tecnología sanitaria que evaluó la eficacia y seguridad de AA en los pacientes con EPIT; Revisiones sistemáticas: se identificó una revisión sistemática que recopiló la información de los estudios publicados hasta el 9 de enero del 2012. En esta evaluación no se describirán sus resultados debido a que la ETS incluye los estudios identificados por esta revisión; Ensayos clínicos: se identificó un ECA que evaluó la eficacia y seguridad de AA en los pacientes con EPIT; Estudios observacionales: se identificaron tres estudios adicionales a los incluidos en la ETS, los que evaluaron los efectos de AA en los pacientes con EPIT; Ensayos Clínicos registrados en www.clinicaltrials.gov: no se identificaron estudios registrados que tengan como objetivo evaluar la eficacia y seguridad de AA en los pacientes con EPIT. CONCLUSIONES: El Instituto de Evaluación de Tecnologías en Salud e Investigación-IETSI, aprueba el uso de AA en el tratamiento de pacientes con EPIT. El presente dictamen preliminar tiene una vigencia de dos años a partir de la fecha de publicación. Dado que la calidad de la evidencia del efecto de AA en desenlaces claves como la sobrevida y calidad de vida es aun baja y el impacto presupuestario del uso de esta tecnología es alta, se establece que el efecto del tratamiento de la EPIT con AA se evaluara con datos de los pacientes que estén recibiendo \r\nAA por el lapso de un año para determinar su impacto en desenlaces clínicos y en la calidad de vida. Esta información servirá para una re-evaluación del medicamento, incluyendo una evaluación económica, al terminar la vigencia del presente dictamen.

Oral delivery of Acid Alpha Glucosidase epitopes expressed in plant chloroplasts suppresses antibody formation in treatment of Pompe mice.

Deficiency of acid alpha glucosidase (GAA) causes Pompe disease in which the patients systemically accumulate lysosomal glycogen in muscles and nervous systems, often resulting in infant mortality. Although enzyme replacement therapy (ERT) is effective in treating patients with Pompe disease, formation of antibodies against rhGAA complicates treatment. In this report, we investigated induction of tolerance by oral administration of GAA expressed in chloroplasts. Because full-length GAA could not be expressed, N-terminal 410-amino acids of GAA (as determined by T-cell epitope mapping) were fused with the transmucosal carrier CTB. Tobacco transplastomic lines expressing CTB-GAA were generated through site-specific integration of transgenes into the chloroplast genome. Homoplasmic lines were confirmed by Southern blot analysis. Despite low-level expression of CTB-GAA in chloroplasts, yellow or albino phenotype of transplastomic lines was observed due to binding of GAA to a chloroplast protein that has homology to mannose-6 phosphate receptor. Oral administration of the plant-made CTB-GAA fusion protein even at 330-fold lower dose (1.5 µg) significantly suppressed immunoglobulin formation against GAA in Pompe mice injected with 500 µg rhGAA per dose, with several-fold lower titre of GAA-specific IgG1 and IgG2a. Lyophilization increased CTB-GAA concentration by 30-fold (up to 190 µg per g of freeze-dried leaf material), facilitating long-term storage at room temperature and higher dosage in future investigations. This study provides the first evidence that oral delivery of plant cells is effective in reducing antibody responses in ERT for lysosomal storage disorders facilitating further advances in clinical investigations using plant cell culture system or in vitro propagation.

Rapid progressive course of later-onset Pompe disease in Chinese patients.

BACKGROUND: Pompe disease presents with a wide variety of phenotypes ranging from a fatal disease in infancy (the infantile-onset form) to other milder later-onset forms. Currently, the clinical manifestations in Chinese patients with later-onset Pompe disease are still not well understood. METHODS: Fifteen Chinese patients who were clinically diagnosed with Pompe disease at later than one year of age at the National Taiwan University Hospital from 1993 to 2009 were included in this study. Confirmatory diagnosis included both biochemical and molecular tests. Patient outcomes after recombinant human acid α-glucosidase (GAA) therapy were also evaluated by assessing the percentage of predicted forced vital capacity in the upright position, hours of daily ventilator use, and the functional status change using Walton Gardner Medwin Scale. RESULTS: The median age at symptom onset was 15 (12-35)years, and the median age at diagnosis was 21 (10-38)years. At the time of diagnosis or shortly after, 8 patients (53%) required mechanical ventilation. A quadriceps muscle biopsy from a 13-year-old boy already showed extensive glycogen storage and muscle fiber destruction. Mutation analysis revealed that the two dual mutations in the GAA gene c.[1935C>A; 1726G>A] (p.[D645E; G576S]) and c.[2238G>C; 1726G>A] (p.[W746C; G576S]) represented 66.5% of the mutated chromosomes. Using mutagenesis, we showed that the p.G576S pseudodeficiency mutation significantly decreased the residual enzyme activity of p.W746C. Most patients responded poorly to recombinant human GAA. CONCLUSIONS: Chinese patients with later-onset Pompe disease often showed onset of symptoms in their second decade of life with rapid disease progression, which is probably due to a specific pattern of GAA gene mutation. Therefore, early diagnosis and early treatment would be necessary to improve the prognosis of these patients.

Strategies for Neoglycan conjugation to human acid α-glucosidase.

Engineering proteins for selective tissue targeting can improve therapeutic efficacy and reduce undesired side effects. The relatively high dose of recombinant human acid α-glucosidase (rhGAA) required for enzyme replacement therapy of Pompe disease may be attributed to less than optimal muscle uptake via the cation-independent mannose 6-phosphate receptor (CI-MPR). To improve muscle targeting, Zhu et al. (1) conjugated periodate oxidized rhGAA with bis mannose 6-phosphate bearing synthetic glycans and achieved 5-fold greater potency in a murine Pompe efficacy model. In the current study, we systematically evaluated multiple strategies for conjugation based on a structural homology model of GAA. Glycan derivatives containing succinimide, hydrazide, and aminooxy linkers targeting free cysteine, lysines, and N-linked glycosylation sites on rhGAA were prepared and evaluated in vitro and in vivo. A novel conjugation method using enzymatic oxidation was developed to eliminate side oxidation of methionine. Conjugates derived from periodate oxidized rhGAA still displayed the greatest potency in the murine Pompe model. The efficiency of conjugation and its effect on catalytic activity were consistent with predictions based on the structural model and supported its use in guiding selection of appropriate chemistries.

Induction of immune tolerance to a therapeutic protein by intrathymic gene delivery.

The efficacy of recombinant enzyme therapy for genetic diseases is limited in some patients by the generation of a humoral immune response to the therapeutic protein. Inducing immune tolerance to the protein prior to treatment has the potential to increase therapeutic efficacy. Using an AAV8 vector encoding human acid α-glucosidase (hGAA), we have evaluated direct intrathymic injection for inducing tolerance. We have also compared the final tolerogenic states achieved by intrathymic and intravenous injection. Intrathymic vector delivery induced tolerance equivalent to that generated by intravenous delivery, but at a 25-fold lower dose, the thymic hGAA expression level was 10,000-fold lower than the liver expression necessary for systemic tolerance induction. Splenic regulatory T cells (Tregs) were apparent after delivery by both routes, but with different phenotypes. Intrathymic delivery resulted in Tregs with higher FoxP3, TGFß, and IL-10 mRNA levels. These differences may account for the differences noted in splenic T cells, where only intravenous delivery appeared to inhibit their activation. Our results imply that different mechanisms may be operating to generate immune tolerance by intrathymic and intravenous delivery of an AAV vector, and suggest that the intrathymic route may hold promise for decreasing the humoral immune response to therapeutic proteins in genetic disease indications.

[Pompe's disease. Part I: pathogenesis and clinical features]. / Pompe-kór -- I. Rész--A betegség patogenezise és klinikuma.

Pompe's disease is an ultra-orphan disease caused by the deficiency of lysosomal alpha-glucosidase. At present, it is the only inherited muscle disorder, which can be treated by replacement of the enzyme. According to the natural course, early infantile and late childhood-juvenile-adult cases are known. Respiratory insufficiency, cardiomyopathy, and muscle hypotonia are cardinal symptoms/signs in infantile Pompe's disease, while cardiomyopathy is absent in adult-onset cases. CK levels are always elevated in the sera of infantile patients. Hip-girdle dystrophy and orthopnoe should alert suspicion in adult patients. Diagnosis is established by decreased activity of the enzyme or mutational analysis. Muscle biopsy can be misleading in adult cases due to absence of glycogen in the examined specimen. In this review, we also discuss our experiences obtained by the treatment of three patients.

Partial phenotypic correction and immune tolerance induction to enzyme replacement therapy after hematopoietic stem cell gene transfer of alpha-glucosidase in Pompe disease.

BACKGROUND: Glycogen storage disease type II (GSDII) or Pompe disease is an inherited disease of glycogen metabolism caused by a lack of functional lysosomal acid alpha-glucosidase (GAA). Affected individuals store glycogen in lysosomes resulting in fatal hypertrophic cardiomyopathy and respiratory failure in the most severe form. Even if enzyme replacement therapy (ERT) has already proven some efficacy, its results remain heterogeneous in skeletal muscle, especially in cross reactive immunological material (CRIM)-negative patients. We investigated for the first time the use of hematopoietic stem cell (HSC) gene therapy in a murine model of GSDII. METHODS: Deficient HSC were transduced with a lentiviral vector expressing human GAA or enhanced green fluorescent protein (GFP) under the control of the retroviral MND promoter and transplanted into lethally irradiated GSDII mice. Animals were then subjected to an ERT protocol for 5 weeks and monitored for metabolic correction and GAA-induced immune reaction. RESULTS: GAA was expressed as a correctly processed protein, allowing a complete enzymatic correction in transduced deficient cells without toxicity. Seventeen weeks after transplantation, a partial restoration of the GAA enzymatic activity was observed in bone marrow and peripheral blood cells of GSDII mice, allowing a significant glycogen clearance in skeletal muscle. ERT induced a robust antibody response in GFP-transplanted mice, whereas no immune reaction could be detected in GAA-transplanted mice. CONCLUSIONS: Lentiviral vector-mediated HSC gene therapy leads to a partial metabolic correction and induces a tolerance to ERT in GSDII mice. This strategy could enhance the efficacy of ERT in CRIM-negative Pompe patients.

Relato do primeiro paciente brasileiro com a forma infantil da doença de Pompe tratado com alfa-glicosidase recombinante humana / Report of the first Brazilian infantile Pompe disease patient to be treated with recombinant human acid alpha-glucosidase

Objetivo: Relatar o primeiro caso de forma infantil da doença de Pompe tratado no Brasil. Descrição: Trata-se de doença de depósito lisossomal que se caracteriza por defeitos da enzima alfa-glicosidase ácida, com acúmulo intracelular de glicogênio, principalmente nos músculos. São descritas a forma infantil e tardia. Desde 2006, está disponível tratamento com enzima recombinante humana. Descreve-se o primeiro caso de forma infantil da doença tratado no Brasil. Trata-se de menina com 2,5 meses de idade e progressão rápida da doença, com perda dos movimentos dos membros, miocardiopatia hipertrófica e insuficiência respiratória aos 7 meses de idade. Após 10 meses de tratamento, apresentou boa resposta clínica, com remissão da insuficiência respiratória, recuperação parcial dos movimentos dos membros e melhora importante do quadro cardiológico. Comentários: Apesar de pouco freqüente, a forma infantil da doença de Pompe é letal. A disponibilidade de tratamento eficaz aumenta a necessidade de conhecimento e diagnóstico precoce da doença.

Objective: To describe the first case of infantile Pompe disease to be treated in Brazil. Description: Pompe disease is a glycogen storage disease related to defects in the acid alpha-glucosidase enzyme, leading to an intracellular accumulation of glycogen, mainly in muscles. Two forms are described: infantile and juvenile. Since 2006, treatment with recombinant human acid alpha-glucosidase has been available. This article describes the first case of infantile Pompe disease treated in Brazil. A girl presented at 2.5 months of age with rapid disease progression, exhibiting severe hypotonia, loss of movements in both upper and lower limbs and hypertrophic cardiomyopathy, progressing to respiratory failure by the age of 7 months. After 10 months of treatment, she exhibited a good clinical response, with remission of the respiratory failure, partial recovery of arm and leg movements and improvement of cardiologic condition. Comments: Despite its low incidence, infantile Pompe disease is lethal. The availability of an effective treatment has created an urgent need to improve knowledge and early diagnosis of this disease.

Enhanced response to enzyme replacement therapy in Pompe disease after the induction of immune tolerance.

Pompe disease, which results from mutations in the gene encoding the glycogen-degrading lysosomal enzyme acid alpha -glucosidase (GAA) (also called "acid maltase"), causes death in early childhood related to glycogen accumulation in striated muscle and an accompanying infantile-onset cardiomyopathy. The efficacy of enzyme replacement therapy (ERT) with recombinant human GAA was demonstrated during clinical trials that prolonged subjects' overall survival, prolonged ventilator-free survival, and also improved cardiomyopathy, which led to broad-label approval by the U.S. Food and Drug Administration. Patients who lack any residual GAA expression and are deemed negative for cross-reacting immunologic material (CRIM) have a poor response to ERT. We previously showed that gene therapy with an adeno-associated virus (AAV) vector containing a liver-specific promoter elevated the GAA activity in plasma and prevented anti-GAA antibody formation in immunocompetent GAA-knockout mice for 18 wk, predicting that liver-specific expression of human GAA with the AAV vector would induce immune tolerance and enhance the efficacy of ERT. In this study, a very low number of AAV vector particles was administered before initiation of ERT, to prevent the antibody response in GAA-knockout mice. A robust antibody response was provoked in naive GAA-knockout mice by 6 wk after a challenge with human GAA and Freund's adjuvant; in contrast, administration of the AAV vector before the GAA challenge prevented the antibody response. Most compellingly, the antibody response was prevented by AAV vector administration during the 12 wk of ERT, and the efficacy of ERT was thereby enhanced. Thus, AAV vector-mediated gene therapy induced a tolerance to introduced GAA, and this strategy could enhance the efficacy of ERT in CRIM-negative patients with Pompe disease and in patients with other lysosomal storage diseases.

Recombinant human acid [alpha]-glucosidase: major clinical benefits in infantile-onset Pompe disease.

BACKGROUND: Pompe disease is a progressive metabolic neuromuscular disorder resulting from deficiency of lysosomal acid alpha-glucosidase (GAA). Infantile-onset Pompe disease is characterized by cardiomyopathy, respiratory and skeletal muscle weakness, and early death. The safety and efficacy of recombinant human (rh) GAA were evaluated in 18 patients with rapidly progressing infantile-onset Pompe disease. METHODS: Patients were diagnosed at 6 months of age and younger and exhibited severe GAA deficiency and cardiomyopathy. Patients received IV infusions of rhGAA at 20 mg/kg (n = 9) or 40 mg/kg (n = 9) every other week. Analyses were performed 52 weeks after the last patient was randomized to treatment. RESULTS: All patients (100%) survived to 18 months of age. A Cox proportional hazards analysis demonstrated that treatment reduced the risk of death by 99%, reduced the risk of death or invasive ventilation by 92%, and reduced the risk of death or any type of ventilation by 88%, as compared to an untreated historical control group. There was no clear advantage of the 40-mg/kg dose with regard to efficacy. Eleven of the 18 patients experienced 164 infusion-associated reactions; all were mild or moderate in intensity. CONCLUSIONS: Recombinant human acid alpha-glucosidase is safe and effective for treatment of infantile-onset Pompe disease. Eleven patients experienced adverse events related to treatment, but none discontinued. The young age at which these patients initiated therapy may have contributed to their improved response compared to previous trials with recombinant human acid alpha-glucosidase in which patients were older.

Nuevas opciones terapeuticas para tratamiento de la Diabetis Mellitus tipo 2 / New therapeutic options for the treatment of diabetis mellitus type 2

La diabetes mellitus Tipo 2 constituye un problema de Salud Pública, por el aumento de su prevalencia que llega actualmente al 7% en nuestra población. Existe una relación entre la morbimortalidad cardiovascular y la hiperglucemia posprandial. Para evitar las complicaciones que presenta esta enfermedad, se debe mantener niveles de Hbalc de 7%, glicemia en ayunas por debajo de 110 mg/dL, y los posprandiales en 180 mg /dL dos horas después de las comidas. Esto se logra con una educación del paciente, dieta, y el uso de los fármacos que en la actualidad se encuentran disponibles, entre los cuales tenemos los insulinosecretores como las sulfonilureas, la repaglinida y nateglinida que actúan controlando la glicemia posprandial; los sensibilizadores de los receptores como son la metformina y las glitazonas; también existen los inhibidores de la alfaglucosidasa. Asimismo, se están utilizando nuevos antidiabéticos cuya acción terapéutica está basada en el aumento de la acción de las hormonas gastrointestinales, que producen una disminución del vaciamiento gástrico, estimulación de la insulina e inhibición de la secreción de glucagon, control de la hiperglicemia posprandial y evitan el aumento del peso corporal, entre estos tenemos la pramlintida que es un análogo de la amilina y la exenamida que es un agonista de los receptores de GLP ( glucagon like peptide), todos estos pueden ser usados en combinación entre si o con insulina para lograr mejores resultados.

Diabetes mellitus Type 2 is a health problem, due to the increase of its prevalence, which at the moment is 7% in our population., in order to avoid the complications that this disease presents it is necessary to maintain levels of Hbalc at 7%, fasting glicemia at levels below 110 mg/dL, and postprandial at 180 mg/dL two hours after meals, because a relation exists between cardiovascular morbimortality and postprandial hyperglicemia. This goal could be obtained by education of the patient, diet, and the use of drugs that at the present time are available among which we have the insulinosecretors like sulfonilureas, repaglinide and nateglinide that control postprandial glicemia. The sensibilization receptors which are metformin and glitazones; also the alfaglucosidase inhibitors, and at the present new antidiabetics are used whose therapeutic action is based on the increase of the action of the gastrointestinal hormones, that produce a diminution of the gastric emptying, insulin stimulation and glucagon inhibition, control of postprandial hyperglicemia and avoid weight gain. Among these we have the pramlintide that is an amyline analogue and exenamide that is an agonist of the GLP receptors (glucagon like peptide). All these can be used in combination with each other or with insulin obtaining better results.