Recombinant Human Alpha-glucosidase Research Articles

Antibodies against recombinant human alpha-glucosidase do not seem to affect clinical outcome in childhood onset Pompe disease

BackgroundEnzyme replacement therapy (ERT) with recombinant human alpha-glucosidase (rhGAA, alglucosidase alfa) has improved survival, motor outcomes, daily life activity and quality of life in Pompe patients. However, ERT in Pompe disease often induces formation of antibodies, which may reduce the efficacy of treatment and can lead to adverse events. In this study antibody formation and their effect on clinical outcome in patients with childhood onset Pompe disease treated with enzyme replacement therapy (ERT) with recombinant human alpha-glucosidase (rhGAA) are analyzed.MethodsEnzyme-linked immunosorbent assay (ELISA) was used to determine anti-rhGAA antibody titers at predefined time points. The effect of antibodies on rhGAA activity (neutralizing effects) was measured in vitro. Clinical effects were evaluated by assessing muscle strength (MRC score) and function (QMFT-score), pulmonary function and infusion associated reactions (IARs).ResultsTwenty-two patients were included (age at start ERT 1.1–16.4 years, median treatment duration 12.4 years). Peak antibody titers were low (< 1:1250) in 9%, intermediate (1:1250–1:31,250) in 68% and high (≥ 1:31250) in 23% of patients; three patients (14%) had more than one titer of ≥ 1:31,250. Four patients (18%) experienced IARs; two patients from the high titer group had 86% of all IARs. Inhibition of intracellular GAA activity (58%) in vitro was found in one sample. The clinical course did not appear to be influenced by antibody titers.ConclusionsNinety-one percent of childhood onset Pompe patients developed anti-rhGAA antibodies (above background level), a minority of whom had high antibody titers at repeated time points, which do not seem to interfere with clinical outcome. High antibody titers may be associated with the occurrence of IARs. Although the majority of patients does not develop high titers; antibody titers should be determined in case of clinical deterioration.

Correction of oxidative stress enhances enzyme replacement therapy in Pompe disease.

Pompe disease is a metabolic myopathy due to acid alpha‐glucosidase deficiency. In addition to glycogen storage, secondary dysregulation of cellular functions, such as autophagy and oxidative stress, contributes to the disease pathophysiology. We have tested whether oxidative stress impacts on enzyme replacement therapy with recombinant human alpha‐glucosidase (rhGAA), currently the standard of care for Pompe disease patients, and whether correction of oxidative stress may be beneficial for rhGAA therapy. We found elevated oxidative stress levels in tissues from the Pompe disease murine model and in patients’ cells. In cells, stress levels inversely correlated with the ability of rhGAA to correct the enzymatic deficiency. Antioxidants (N‐acetylcysteine, idebenone, resveratrol, edaravone) improved alpha‐glucosidase activity in rhGAA‐treated cells, enhanced enzyme processing, and improved mannose‐6‐phosphate receptor localization. When co‐administered with rhGAA, antioxidants improved alpha‐glucosidase activity in tissues from the Pompe disease mouse model. These results indicate that oxidative stress impacts on the efficacy of enzyme replacement therapy in Pompe disease and that manipulation of secondary abnormalities may represent a strategy to improve the efficacy of therapies for this disorder.

POMPE DISEASE: EP.197 Antibodies against recombinant human alpha-glucosidase do not affect clinical outcome in childhood onset Pompe disease

POMPE DISEASE: EP.197 Antibodies against recombinant human alpha-glucosidase do not affect clinical outcome in childhood onset Pompe disease

Follow-up of late-onset Pompe disease patients with muscle magnetic resonance imaging reveals increase in fat replacement in skeletal muscles.

BackgroundLate‐onset Pompe disease (LOPD) is a genetic disorder characterized by progressive degeneration of the skeletal muscles produced by a deficiency of the enzyme acid alpha‐glucosidase. Enzymatic replacement therapy with recombinant human alpha‐glucosidase seems to reduce the progression of the disease; although at the moment, it is not completely clear to what extent. Quantitative muscle magnetic resonance imaging (qMRI) is a good biomarker for the follow‐up of fat replacement in neuromuscular disorders. The aim of this study was to describe the changes observed in fat replacement in skeletal muscles using qMRI in a cohort of LOPD patients followed prospectively.MethodsA total of 36 LOPD patients were seen once every year for 4 years. qMRI, several muscle function tests, spirometry, activities of daily living scales, and quality‐of‐life scales were performed on each visit. Muscle MRI consisted of two‐point Dixon studies of the trunk and thigh muscles. Computer analysis of the images provided the percentage of muscle degenerated and replaced by fat in every muscle (known as fat fraction). Longitudinal analysis of the measures was performed using linear mixed models applying the Greenhouse–Geisser test.ResultsWe detected a statistically significant and continuous increase in mean thigh fat fraction both in treated (+5.8% in 3 years) and in pre‐symptomatic patients (+2.6% in 3years) (Greenhouse–Geisser p < 0.05). As an average, fat fraction increased by 1.9% per year in treated patients, compared with 0.8% in pre‐symptomatic patients. Fat fraction significantly increased in every muscle of the thighs. We observed a significant correlation between changes observed in fat fraction in qMRI and changes observed in the results of the muscle function tests performed. Moreover, we identified that muscle performance and mean thigh fat fraction at baseline visit were independent parameters influencing fat fraction progression over 4 years (analysis of covariance, p < 0.05).ConclusionsOur study identifies that skeletal muscle fat fraction continues to increase in patients with LOPD despite the treatment with enzymatic replacement therapy. These results suggest that the process of muscle degeneration is not stopped by the treatment and could impact muscle function over the years. Hereby, we show that fat fraction along with muscle function tests can be considered a good outcome measures for clinical trials in LOPD patients.

Effects of immunomodulation in classic infantile Pompe patients with high antibody titers

PurposeTo evaluate whether immunomodulation can eliminate high sustained antibody levels, and thereby improve clinical outcome in classic infantile Pompe patients receiving enzyme replacement therapy (ERT) with recombinant human alpha-glucosidase (rhGAA).MethodsThree patients (two cross-reactive immunologic material (CRIM) negative) with high sustained antibodies received a three-week treatment protocol with Rituximab and Bortezomib, followed by daily Rapamycin and monthly IVIG. Patients received 40 mg/kg/week rhGAA. Antibody titers were measured using ELISA. Neutralizing effects on cellular uptake were determined. Clinical efficacy was measured in terms of (ventilator-free) survival, reduction in left ventricular mass index (LVMI) and improvement in motor function.ResultsBefore immunomodulation anti-rhGAA antibody titers ranged from 1:156,250 to 1:781,250 and at last assessment from 1:31,250 to 1:156,250. Neutralizing effects of anti-rhGAA antibody titers (observed in two patients) disappeared. Infusion-associated reactions were no longer present. Immunomodulation resulted in substantial increases of aspartate transaminase, alanine transaminase, and creatine kinase levels. The two CRIM-negative patients who could walk at start of immunomodulation maintained their ability to walk; the patient who had lost this ability did not regain it.ConclusionsTo some extent, the immunomodulation protocol used in our study reduced antibody titers, but it did not eliminate them. Overall, there have been few reports on secondary immunomodulation, and various protocols have been applied. Future research should seek to identify the most successful immunomodulation protocol in patients with high sustained titers.

Enzymatic replacement therapy in patients with late-onset Pompe disease – 6-Year follow up

IntroductionLate-onset Pompe disease (LOPD) is a progressive metabolic myopathy, affecting skeletal muscles, which, if untreated, leads to disability and/or respiratory failure. The enzyme replacement therapy (ERT) improves muscle strength and respiratory function and prevents disease progression. We present a 6-year follow-up of 5 patients with LOPD treated with ERT. MethodsFive patients with LOPD received ERT: two started treatment in 2008, other two in 2010 and one in 2011. All patients received recombinant human alpha-glucosidase in dose 20mg/kg intravenously every two weeks. Physical performance was assessed in 6-minute walk test (6MWT) and spirometry was performed to examine FVC and FEV1. Liver enzymes, CK levels were also assessed. ResultsThe walking distance in 6MWT increased by average 16.9±2.26% in the first three years of treatment. Similar changes were detected in spirometry: the most significant FVC increase was observed in two patients with the highest FVC values before treatment, which increased to normal values adjusted for age and sex in three years of treatment, that is by 28% and 34%. In two other patients FVC reached 88% and 76% of predicted values. ERT also improved the liver and muscle enzymes levels. ConclusionThe improvements of exercise tolerance and FVC were observed in all patients in the first three years of treatment and were the most pronounced in the longest-treated patients and with the least severe neurological and respiratory symptoms. Our research suggests that early start of the ERT results in higher improvement of respiratory and ambulation functions.

Alglucosidase alfa: 5 years of experience in late-onset Pompe disease

Glycogen storage disease type 2, Pompe disease, is a progressive muscle disorder with a wide range of phenotypic presentations, caused by an inherited deficiency of the enzyme acid alpha-glucosidase. Although only a few patients have been treated with recombinant human alpha-glucosidase from rabbit milk since 2004, enzyme replacement therapy (ERT) with alglucosidase alfa has been licensed for the treatment of Pompe disease since 2006. Here, a systematic review [1] evaluates the clinical efficacy and safety of alglucosidase alfa treatment in juvenile and adult patients with late-onset Pompe disease (LOPD). Studies of alglucosidase alfa treatment in patients with LOPD, published up to October 2012, were identified using an electronic search of the EMBASE and MEDLINE databases, and manual searches of the reference lists. Data on ERT outcomes were extracted from the selected papers and analyzed descriptively. No statistical analyses were performed owing to data heterogeneity. Twenty-two studies containing clinical data from 437 LOPD patients were analyzed. Overall, at least two-thirds of patients were stabilized or exhibited improvements in creatine kinase levels, and muscular and/or respiratory function following treatment with alglucosidase alfa. Enzyme replacement therapy was well tolerated; the majority of adverse events were mild or moderate infusion-related reactions. Alglucosidase alfa treatment offers an effective and well tolerated treatment that attenuates the progression of LOPD in the majority of patients. Although first insights are upcoming, further research is required to investigate reliable prognostic factors such as age at treatment start, phenotypic presentation, and genotypic characteristics, of which may enable better clinical and therapeutic management of LOPD patients.

Enzyme replacement therapy in late-onset Pompe disease: a systematic literature review

Glycogen storage disease type 2/Pompe disease is a progressive muscle disorder with a wide range of phenotypic presentations, caused by an inherited deficiency of acid alpha-glucosidase. Since 2004 only a limited number of patients have been treated with recombinant human alpha-glucosidase from rabbit milk whereas since 2006 enzyme replacement therapy (ERT) with alglucosidase alfa has been licensed for the treatment of Pompe disease. This systematic review evaluates the clinical efficacy and safety of alglucosidase alfa treatment of juvenile and adult patients with late-onset Pompe disease (LOPD). Studies of alglucosidase alfa treatment of LOPD patients-published up to January 2012-were identified by electronic searching of the EMBASE and MEDLINE databases, and manual searching of the reference lists. Data on ERT outcomes were extracted from selected papers and analyzed descriptively. No statistical analysis was performed owing to data heterogeneity. Twenty-one studies containing clinical data from 368 LOPD patients were analyzed. Overall, at least two-thirds of patients were stabilized or had improved creatine kinase levels and muscular and/or respiratory function following treatment with alglucosidase alfa. ERT was well tolerated; most adverse events were mild or moderate infusion-related reactions. In conclusion, alglucosidase alfa treatment is effective and well tolerated and attenuates progression of LOPD in most patients. Further research is required to investigate factors such as age at diagnosis, phenotypic presentation, and genotypic characteristics, identification of which may enable better clinical and therapeutic management of LOPD patients.

Guía clínica de la enfermedad de Pompe de inicio tardío

Before 2006, Pompe disease or glycogenosis storage disease type II was an incurable disease whose treatment was merely palliative. The development of a recombinant human alpha-glucosidase enzymatic replacement therapy has become the first specific treatment for this illness. The aim of this guide is to serve as reference for the management of the late-onset Pompe disease, the type of Pompe disease that develops after one year of age. In the guide a group of Spanish experts make specific recommendations about diagnosis, follow-up and treatment of this illness. With regard to diagnosis, the dried blood spots method is essential as the first step for the diagnosis of Pompe disease. The confirmation of the diagnosis of Pompe disease must be made by means of an study of enzymatic activity in isolated lymphocytes or a mutation analysis of the alpha-glucosidase gene. With regard to treatment with enzymatic replacement therapy, the experts say that is effective improving or stabilizating the motor function and the respiratory function and it must be introduced when the first symptoms attributable to Pompe disease appear.

Observational clinical study in juvenile-adult glycogenosis type 2 patients undergoing enzyme replacement therapy for up to 4 years

The objective of this study was to describe a large Italian cohort of patients with late-onset glycogen storage disease type 2 (GSDII) at various stages of disease progression and to evaluate the clinical effectiveness of alglucosidase alpha enzyme replacement therapy (ERT). Previous studies showed in late-onset patients ERT efficacy against placebo and variable response in uncontrolled studies. Seventy-four juvenile or adult GSDII patients were treated with ERT in a multicenter open label, non-randomized study, from 12 months up to 54 months. Recombinant human alpha glucosidase (rh-GAA) was injected by intravenous route at 20 mg/kg every second week. Patients were divided into three groups according to ERT duration: Group A received treatment for 12-23 months (n = 16), Group B for 24-35 months (n = 14), and Group C for more than 36 months (n = 44). Clinical assessment included a 6-min walk test (6MWT), forced vital capacity (FVC), the Walton and Gardner-Medwin score, the number of hours of ventilation, body mass index, echocardiography and blood creatine kinase (CK). Included in our cohort were 33 males and 41 females (M:F = 0.8:1), with a mean age at first symptoms of 28.3 years (range 2-55 years) and a mean age of 43 years at study entry (range 7-72 years). Seven wheelchair bound patients, as well as 27 patients requiring ventilation support, were included. After treatment we could observe an increase in distance walked on the 6MWT in the large majority of patients (48/58; 83%), with an overall mean increase of 63 m (from 320 ± 161 to 383 ± 178 m). After treatment in the majority of patients FVC was improved or unchanged (45/69; 65%). In ventilated patients we observed an improvement in average number of hours off the ventilator (from 15.6 to 12.1 h). Six patients stopped mechanical ventilation and two others started it. The effect of therapy was not related to ERT duration. Nine of 64 patients (13%) that underwent to echocardiography showed a variable degree of cardiac hypertrophy (left ventriculum or septum), and a positive effect was observed after 36 months of ERT in one adult case. Discontinuation of treatment occurred in four patients: one drop-off case, one patient died for a sepsis after 34 months of treatment and two patients stopped ERT for worsening of general clinical condition. Mild adverse effects were observed in four cases (5%). This study represents the largest cohort of late-onset GSDII patients treated with ERT, and confirm a positive effect of treatment. These results, obtained in a large case series on therapy, indicate a favourable effect of ERT therapy, even in more advanced stage of the disease.

Close monitoring of initial enzyme replacement therapy in a patient with childhood-onset Pompe disease

Pompe disease is classified into infantile and late-onset (childhood and adult) forms based on onset age and degree of organ involvement. While benefits of enzyme replacement therapy (ERT) for the infantile form have been confirmed, efficacy for late-onset forms reportedly varies. We report close monitoring of initial ERT, focusing especially on the first year, in a 12-year-old boy with childhood-onset Pompe disease. At age 10, he started ERT at 20 mg/kg every other week. Respiratory and motor functions were evaluated at each infusion, and by skeletal muscle computed tomography (CT) and cardiac echography every 4 months. He gained the ability to climb stairs without a rail and % vital capacity improved just 1.5 months after starting ERT. Grip power, manual muscle testing (MMT) and the timed and 6-min walking distance tests (6MWT) improved promptly, paralleling improvements in clinical symptoms. However, this steady improvement stopped around 8 months, with deterioration to the initial level by about 24 months. Antibody against recombinant human alpha-glucosidase was very low at 15 months; therefore, the lack of treatment response did not completely correspond to antibody production. On the other hand, cardiac wall thickening worsened after 4 months, then improved to better than baseline after 8 months, and this improvement was well maintained. Among our set parameters, the timed test results corresponded better to his changing clinical course than did grip power, MMT or 6-min walking test results.

Outcome of patients with infantile Pompe's disease treated with recombinant human alpha-glucosidase (Alglucosidase alfa) in Germany – A retrospective survey

Initial clinical studies with intravenous application of recombinant human alpha-glucosidase showed improved survival, cardiac and respiratory function, and motor development in infants with Pompe's disease. Since experience with enzyme replacement therapy (ERT) in Pompe's disease is still limited, we aimed to achieve an overview of results obtained with this form of treatment in Germany. To accomplish this, we analyzed retrospectively the data of 13 patients with infantile Pompe's disease (9 of German and 4 of Turkish descent) treated with Alglucosidase alfa. Age at onset of first symptoms was 1.5±1.0, age at diagnosis 3.8±3.0, and age at start of ERT 4.9±4.1 months. 4 out of 13 subjects (31%) died during therapy and 1 infant became ventilator-dependent. Mean age at death was 18.6±6.3 months while the mean age of the surviving patients is 34.5±24.1 months. The age of the oldest living child is 5.4 years. Reduction of cardiac size was attained in 12 subjects whereas one individual deceased due to cardiac arrhythmia resulting from progressive hypertrophic cardiomyopathy. Among the 7 patients older than age 12 months, 1 is unable to sit, 1 sits with support 3 sit without support and achieved some form of ambulation, and 2 attained free walking. Recurrent pneumonia, swallowing difficulties, and gastro-esophageal reflux were frequent complications during ERT. Motor development is nearly normal in 2 out of 3 subjects in whom ERT was started within the first six weeks of life, while the remainder is not able to sit without support at age 14 months. This study confirms previous investigations that demonstrated prolonged survival in infants with Pompe's disease receiving ERT. Our data also suggest that substantial reduction of cardiac hypertrophy can be achieved in nearly all patients, but that the effects of ERT on motor development are variable. Even infants treated early seem not always to realize major gains in motor functions.

Cardiomyopathy in Pompe's disease

Pompe's disease (glycogen storage disease type II) is a lysosomal storage disorder resulting from a deficiency in alpha 1, 4 glucosidase. Prognosis is poor because of heart involvement. Treatment in adult form relies on supportive therapy. Enzyme replacement therapy with recombinant human alpha glucosidase remains a hope for patients.

Long-Term Enzyme Replacement Therapy for Pompe Disease With Recombinant Human Alpha-glucosidase Derived From Chinese Hamster Ovary Cells

Pompe disease is a rare autosomal recessive myopathy due to the deficiency of lysosomal acid alpha-glucosidase. Clinical phenotypes range from the severe classic infantile form (hypotonia and hypertrophic cardiomyopathy), to milder late onset forms (skeletal myopathy and absence of significant heart involvement). Enzyme replacement therapy with recombinant human alpha-glucosidase derived from either rabbit milk or Chinese hamster ovary cells has been introduced and is undergoing clinical trials. Reported is a long-term follow-up of 3 Pompe patients presenting without cardiomyopathy, treated with recombinant human alpha-glucosidase derived from Chinese hamster ovary cells. This study suggests that enzyme replacement therapy can lead to significant motor and respiratory improvement in the subgroup of patients who start the therapy before extensive muscle damage has occurred. The recombinant enzyme derived from Chinese hamster ovary cells, administered at doses significantly higher than previously reported, appears to have the same safety as the drug derived from rabbit milk.

Long-term intravenous treatment of Pompe disease with recombinant human alpha-glucosidase from milk.

Objective. Recent reports warn that the worldwide cell culture capacity is insufficient to fulfill the increasing demand for human protein drugs. Produc- tion in milk of transgenic animals is an attractive alter- native. Kilogram quantities of product per year can be obtained at relatively low costs, even in small animals such as rabbits. We tested the long-term safety and effi- cacy of recombinant human -glucosidase (rhAGLU) from rabbit milk for the treatment of the lysosomal stor- age disorder Pompe disease. The disease occurs with an estimated frequency of 1 in 40 000 and is designated as orphan disease. The classic infantile form leads to death at a median age of 6 to 8 months and is diagnosed by absence of -glucosidase activity and presence of fully deleterious mutations in the -glucosidase gene. Cardiac hypertrophy is characteristically present. Loss of muscle strength prevents infants from achieving developmental milestones such as sitting, standing, and walking. Milder forms of the disease are associated with less severe mu- tations and partial deficiency of -glucosidase. Methods. In the beginning of 1999, 4 critically ill pa- tients with infantile Pompe disease (2.5- 8 months of age) were enrolled in a single-center open-label study and treated intravenously with rhAGLU in a dose of 15 to 40 mg/kg/week. Results. Genotypes of patients were consistent with the most severe form of Pompe disease. Additional mo- lecular analysis failed to detect processed forms of -glu- cosidase (95, 76, and 70 kDa) in 3 of the 4 patients and revealed only a trace amount of the 95-kDa biosynthetic intermediate form in the fourth (patient 1). With the more sensitive detection method, 35S-methionine incorpora-

Enzyme replacement therapy in late-onset Pompe's disease: a three-year follow-up.

Pompe's disease is an autosomal recessive myopathy. The characteristic lysosomal storage of glycogen is caused by acid alpha-glucosidase deficiency. Patients with late-onset Pompe's disease present with progressive muscle weakness also affecting pulmonary function. In search of a treatment, we investigated the feasibility of enzyme replacement therapy with recombinant human alpha-glucosidase from rabbit milk. Three patients (aged 11, 16, and 32 years) were enrolled in the study. They were all wheelchair-bound and two of them were ventilator dependent with a history of deteriorating pulmonary function. After 3 years of treatment with weekly infusions of alpha-glucosidase, the patients had stabilized pulmonary function and reported less fatigue. The youngest and least affected patient showed an impressive improvement of skeletal muscle strength and function. After 72 weeks of treatment, he could walk without support and finally abandoned his wheelchair. Our findings demonstrate that recombinant human alpha-glucosidase from rabbit milk has a therapeutic effect in late-onset Pompe's disease. There is good reason to continue the development of enzyme replacement therapy for Pompe's disease and to explore further the production of human therapeutic proteins in the milk of mammals.

Morphological changes in muscle tissue of patients with infantile Pompe's disease receiving enzyme replacement therapy.

Pompe's disease (glycogen storage disease type II) is an autosomal recessive myopathy caused by lysosomal alpha-glucosidase deficiency. Enzyme replacement therapy (ERT) is currently under development for this disease. We evaluated the morphological changes in muscle tissue of four children with infantile Pompe's disease who received recombinant human alpha-glucosidase from rabbit milk for 72 weeks. The patients were 2.5-8 months of age at entry. Prior to treatment, all patients showed lysosomal glycogen storage in skeletal and smooth muscle cells, vascular endothelium, Schwann cells, and perineurium. The first response to treatment was noticed in vascular endothelium and in peripheral nerves after 12 weeks of treatment at an enzyme dose of 15-20 mg/kg. Increasing the dose to 40 mg/kg led, after 72 weeks of treatment, to a reduction of glycogen storage and substantial improvement of muscle architecture in the least affected patient. Not all patients responded equally well, possibly due to differences in degree of glycogen storage and concomitant muscle pathology at the start of treatment. We conclude that intravenous administration of recombinant human alpha-glucosidase from rabbit milk can improve muscle morphology in classic infantile Pompe's disease when treatment is started before irreversible damage has occurred.

Recombinant human α-glucosidase from rabbit milk in Pompe patients

Pompe's disease is a fatal muscular disorder caused by lysosomal alpha-glucosidase deficiency. In an open-label study, four babies with characteristic cardiomyopathy were treated with recombinant human alpha-glucosidase (rhGAA) from rabbit milk at starting doses of 15 mg/kg or 20 mg/kg, and later 40 mg/kg. The enzyme was generally well tolerated. Activity of alpha-glucosidase normalised in muscle. Tissue morphology and motor and cardiac function improved. The left-ventricular-mass index decreased significantly. We recommend early treatment. Long-term effects are being studied.