Effect of long term enzyme replacement therapy in late onset Pompe disease: A single-centre experience

Late onset Pompe disease (LOPD) is a slowly progressive metabolic myopathy with variable clinical severity. The advent of enzyme replacement therapy (ERT) has modified the natural course of the disease, though the treatment effect on adult patients is modest compared to infants with the classic form. This study aims to describe the long-term clinical outcome of the Greek LOPD cohort, as assessed by 6 min walk test, muscle strength using MRC grading scale and spirometry. ERT efficacy was estimated using statistical methodology that is novel in the context of Pompe disease, which at the same time is well-suited to longitudinal studies with small samples and missing data (local non-linear regression analysis). Improvement over baseline was significant at 1 year for motor performance and muscle strength (p < 0.05), and at 2 years for FVC-U and FVC-S (p < 0.05). A subgroup analysis showed that the onset of the disease before adulthood (18 years), a male gender, and a latency of more than 2 years between the onset of symptoms and ERT administration are unfavorable prognostic factors. Conclusively, this study presents longitudinal data from the Greek LOPD cohort supporting previous observations, that therapeutic delay is related to worse prognosis and treatment effects may decline after several years of ERT.     

A retrospective study of six patients with late-onset Pompe disease

IntroductionPompe's disease, also called glycogen storage disease type II or acid maltase deficiency, is an autosomal recessive disease caused by an enzymatic deficiency of acid-alpha-glucosidase (GAA). This deficiency causes an accumulation of intralysosomal glycogen in different organs. The classic form appears in the newborn with a very severe hypotonia and cardiomyopathy, which lead to death before age two. Less frequently, the disease appears only in childhood or in adult life, so called late-onset Pompe's disease. This form causes a very progressive limb-girdle myopathy and restrictive respiratory failure. The diagnosis is based on a low level of GAA either in the muscle biopsy or in the leucocytes. We report six cases of late-onset Pompe's disease from the Languedoc-Roussillon district.MethodOur work was a retrospective analysis of all cases of Pompe disease diagnosed in adults between 1975 and 2006 at the Montpellier and Nîmes Universitary Hospital. We describe the clinical presentation and course of this form and explain the diagnostic approach. Results. The mean age at onset was 44.3 years (range: 36–60 years). The first symptom was fatigability (50%), gait difficulty (50%) and dyspnea (16%). The mean delay from symptom onset to diagnosis was 8.4 years (range: 17 years). Fatal outcome due to respiratory failure was noted in three patients. The mean time between symptom onset and death (four patients) was 20.75 years (range: 37 years). The diagnosis was made on the muscle biopsy showing a low level of GAA. Muscle was strictly normal on the morphologic study in one patient, pointing out the requirement for enzymatic analysis. Molecular confirmation was available in one patient.DiscussionLate-onset Pompe's disease is a possible cause of limb-girdle myopathy. Respiratory involvement is a characteristic feature. Enzymatic assay of GAA activity on the muscle biopsy is required for certain diagnosis.ConclusionIt is very important to recognize the adult form of Pompe's disease, a possible cause of limb-girdle myopathy, in order to search for respiratory failure and propose non-invasive ventilation if necessary. Moreover, substitutive therapy (recombinant acid-alpha-glucosidase) has shown efficiency for the classical infantile form of Pompe's disease and such treatment could be proposed for the adult form if larger studies confirm its efficacy.     

Quantitative computed tomography for enzyme replacement therapy in Pompe disease

Objective: Pompe disease is an autosomal recessive disorder caused by deficiency of the lysosomal enzyme, acid alpha-glucosidase (GAA). To the best of our knowledge, no studies have reported the results of systematic and sequential CT analyses before and during ERT. In this study we have treated three patients with late onset Pompe disease by ERT, and investigated the efficacy of treatment by computed tomography number. Methods: We measured the serial changes in the computed tomography (CT) number of multiple organs in three patients with late onset of Pompe disease during 24 months of enzyme replacement therapy (ERT). Results: Before treatment, the liver and muscle CT numbers were higher in these patients than in the controls. The liver CT number decreased after performing ERT. Furthermore, the urinary glucose tetrasaccharide levels, a biomarker of glycogen accumulation, were elevated before ERT and reduced thereafter. Conclusions: The findings in these cases suggest that the elevation of the liver CT number represents glycogen accumulation in the liver and that the analysis of the liver CT number is therefore a useful tool for assessing the efficacy of ERT.     

The impact of interrupting enzyme replacement therapy in late-onset Pompe disease

Journal of Neurology - Late-onset Pompe disease (LOPD) is a rare autosomal recessive disorder caused by mutations in the GAA gene, leading to progressive weakness of locomotor and respiratory...     

24-months results in two adults with Pompe disease on enzyme replacement therapy

Objective

Late-onset Pompe disease is a slowly progressive disorder resulting from deficiency of lysosomal acid alpha-glucosidase (GAA). Since 2006, an intravenous enzyme replacement therapy (ERT) with Myozyme™ (alglucosidase alfa) is available but long-term experience with ERT in late-onset Pompe disease is still limited.

Methods

Two adult patients with impaired walking ability and disease duration of 10 and 13 years, respectively received ERT over a period of 24 months. Clinical and functional parameters including dynamometer-based assessment of proximal muscle strength were registered longitudinally.

Results

In both patients some gain in function and physical endurance could be observed which was collaborated by stable dynamometer tests. No serious adverse events occurred and no patient required de novo ventilation.

Conclusion

The clinical results from our data base imply that long term enzyme replacement therapy seems to somewhat affect functionality and quality of life and can stabilize the otherwise progressive disease course in patients with late-onset Pompe disease.     

STIG study: real-world data of long-term outcomes of adults with Pompe disease under enzyme replacement therapy with alglucosidase alfa

Journal of Neurology - Pompe disease is one of the few neuromuscular diseases with an approved drug therapy, which has been available since 2006. Our study aimed to determine the real-world...     

Infantile Pompe disease: clinical and genetic characteristics with an experience of enzyme replacement therapy

Pompe disease is an autosomal recessive disorder caused by lysosomal acid α-glucosidase deficiency. Infantile-onset Pompe disease presents with cardiomyopathy and hypotonia, leading to premature death. This article describes 7 infantile Pompe disease cases and provides their molecular bases and clinical outcomes after enzyme replacement therapy for the first time in Korea. Molecular genetic analyses revealed the presence of 9 different mutations, including 5 novel mutations (c.2171C>A, c.2774C>T, c.1582_3de12, c.1261_1263Tms, and c.1322_1326+9de114). The most common mutation in these 7 patients was c.1316T>A (28%). Four patients received intravenous recombinant human acid α-glucosidase therapy for 2 years, on average, without significant side effects during the treatment course. They all exhibited increased muscle power, with considerable improvement in cardiac function. Pompe disease is heterogeneous regarding both clinical features and molecular characteristics. Early identification of Pompe disease is very important, considering that enzyme replacement therapy is a safe and effective treatment for early-onset patients.     

Clinical efficacy of the enzyme replacement therapy in patients with late-onset Pompe disease: a systematic review and a meta-analysis

Journal of Neurology - In patients with late-onset Pompe disease (LOPD), the efficacy of the enzyme replacement therapy (ERT) with recombinant human alpha-glucosidase (rhGAA) is difficult to...     

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.     

Adult Pompe disease: clinical manifestations and outcome of the first Greek patients receiving enzyme replacement therapy

Objective

Pompe disease is an autosomal recessive lysosomal disorder caused by α-glucosidase deficiency. A specific treatment for the disease with enzyme replacement therapy is currently available. The aim of the present study is to describe the clinical manifestations and the effect of treatment in the first Greek patients with the adult form of the disease.

Methods

Five Greek patients with adult onset Pompe disease aged between 40 and 73 years received 20 mg/kg Myozyme intravenously at two weekly intervals over a different period. Clinical and functional parameters were longitudinally registered.

Results

Proximal muscle weakness and respiratory insufficiency were the most common manifestations of the disease, but their severity was different even among patients with similar genotype. The effect of treatment varied with most patients experiencing some improvement in muscle strength and fatigability, while the most severely affected patient did not benefit and stopped therapy.

Conclusion

No clear genotype-phenotype correlation emerges from our study. The different effect of treatment on our patients seems to be mainly related to their pre-treatment condition and can be reliably assessed only on a long term basis.     

Obstructive sleep apnea in late-onset Pompe disease treated by enzyme replacement therapy

Obstructive sleep apnea is a common complication of Pompe disease. Treatment for obstructive sleep apnea in patients with Pompe disease is similar to treatment in the general population, typically involving positive airway pressure therapy. We present a case in which a patient with late-onset Pompe disease was able to discontinue positive airway pressure therapy after treatment with enzyme replacement therapy for his Pompe disease. It is likely that an improvement in muscle tone from the enzyme replacement therapy was sufficient to eliminate his obstructive sleep apnea. Pharmacological therapies for obstructive sleep apnea are lacking but could apply to certain populations, such as Pompe disease.     

Eight years experience with enzyme replacement therapy in two children and one adult with Pompe disease

Pompe disease (type 2 glycogenosis, acid maltase deficiency) is a disorder affecting skeletal and cardiac muscle, caused by deficiency of acid alpha-glucosidase. In 2006 enzyme therapy with recombinant human alpha-glucosidase received marketing approval based on studies in infants. Results in older children and adults are awaited. Earlier we reported on the 3-year follow-up data of enzyme therapy in two adolescents and one adult. In the present study these patients were followed for another 5 years. Two severely affected patients, wheelchair and ventilator dependent, who had shown stabilization of pulmonary and muscle function in the first 3 years, maintained this stabilization over the 5-year extension period. In addition patients became more independent in daily life activities and quality of life improved. The third moderately affected patient had shown a remarkable improvement in muscle strength and regained the ability to walk over the first period. He showed further improvement of strength and reached normal values for age during the extension phase. The results indicate that both long-term follow-up and timing of treatment are important topics for future studies.     

Swiss national guideline for reimbursement of enzyme replacement therapy in late-onset Pompe disease

Glycogen storage disease type II is a rare multi-systemic disorder characterised by an intracellular accumulation of glycogen due a mutation in the acid alpha glucosidase (GAA) gene. The level of residual enzyme activity, the genotype and other yet unknown factors account for the broad variation of the clinical phenotype. The classical infantile form is characterised by severe muscle hypotonia and cardiomyopathy leading to early death. The late-onset form presents as a limb girdle myopathy with or without pulmonary dysfunction. Enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA) in infants is life saving. In contrast, therapeutic efficacy of rhGAA in the late-onset form is modest. High expenses of rhGAA, on-going infusions and poor pharmacokinetic efficacy raised a discussion of the cost effectiveness of ERT in late-onset Pompe disease in Switzerland. This discussion was triggered by a Swiss federal court ruling which confirmed the reluctance of a health care insurer not to reimburse treatment costs in a 67-year-old female suffering from Pompe disease. As a consequence of this judgement ERT was stopped by all insurance companies in late-onset Pompe patients in Switzerland regardless of their clinical condition. Subsequent negotiations lead to the release of a national guideline of the management of late-onset Pompe disease. Initiation and limitation of ERT is outlined in a national Pompe registry. Reimbursement criteria are defined and individual efficacy of ERT with rhGAA is continuously monitored.     

Pompe disease (glycogen storage disease type II): clinical features and enzyme replacement therapy

Pompe disease (glycogen storage disease type II, acid maltase deficiency) is a progressive metabolic myopathy caused by deficiency of the lysosomal enzyme acid alpha-glucosidase. This leads to an accumulation of glycogen in various tissues of the body, most notably in skeletal muscle. The disease has an autosomal recessive inheritance with a predicted frequency of 1 :40.000. Pompe disease is a continuous spectrum but for clinical practice different subtypes are recognized. The classic infantile form of the disease occurs in infants (shortly after birth) and is characterized by generalized hypotonia, failure to thrive, and cardiorespiratory failure. Patients usually die within the first year of life. The non-classic or late-onset form of the disease may occur at any age in childhood or adulthood. It presents predominantly as a slowly progressive proximal myopathy, with or without respiratory failure. Enzyme replacement therapy (ERT) is under study as treatment for the disease. The first results with recombinant human alpha-glucosidase are promising and a registered therapy seems near. Beneficial effects of ERT have been reported both in patients with the classic infantile form as well as in patients with the non-classic or late-onset form of the disease. The best therapeutic results are achieved when ERT is started early in the course of symptom development and before irreversible muscular damage has occurred. Detailed knowledge about the natural course of the disease becomes more and more essential to determine the indication and timing of treatment.     

Discontinuation of enzyme replacement therapy in adults with Pompe disease: Evaluating the European POmpe Consortium stop criteria

Enzyme replacement therapy for Pompe disease received market authorization in 2006. To implement this costly treatment in the Netherlands in the most sensible way, a multidisciplinary expert committee was installed. We evaluated decision making in adult patients in relation to the European POmpe Consortium stop criteria. Of 125 adult Pompe patients, 111 started treatment; subsequently treatment stopped in 24 patients (21%). In 10 patients, treatment was discontinued for medical or personal reasons, as defined in the six stop criteria (median treatment duration: 2.1 years, range: 0.3–14.6 years). Three of these patients continued follow-up (follow-up: 1.3–8.0 years), these patients did not display a more rapid decline after discontinuation. In 14 of 24 patients, therapy ended at time of death. In 10 patients death was related to Pompe disease (median treatment duration: 7.2 years, range: 0.4–10.3 years). All 10 patients were severely affected at start of treatment, treatment had elicited positive effects in eight. The European POmpe Consortium guidelines worked well in decision making on stopping treatment. However, (re)evaluation of the rationale for continuation of treatment in advanced disease stage is not addressed. We suggest to add this to the treatment evaluation and to handle treatment decisions in a multidisciplinary expert team.     

Token reinforcement therapy with chronic psychiatric patients: A three-year evaluation

A three year evaluation of a token economy program revealed significant differences in the direction of change in five out of seven behavioral ratings. The subjects were 143 chronic neuropsychiatric patients. Length of hospitalization and length of time in the token economy program were positively correlated with change in behavioral ratings. Readmission rates for patients discharged from the hospital were encouragingly low.