Enzyme Replacement Therapy In Pompe Disease Research Articles

Home-based enzyme replacement therapy in children and adults with Pompe disease; a prospective study

BackgroundPompe disease is a lysosomal storage disease treated with life-long enzyme replacement therapy (ERT). Home-based ERT has been provided in the Netherlands since 2008 because it diminishes the burden of treatment, increases patient flexibility and autonomy, and is thus a more patient-centred approach to ERT.MethodsAll Dutch Pompe patients receiving alglucosidase alfa infusions at home were approached to participate in a questionnaire to validate the safety of home-based ERT. Prospective data on symptoms occurring during or within 48 h after infusion and retrospective data on infusion associated reactions (IARs) in the last three months were collected four times during one year.ResultsIn total, 116 out of 120 eligible patients (17 classic infantile, 2 atypical infantile, 15 childhood onset and 82 adult) filled out 423 questionnaires (response rate: 88.1%). Symptoms during or after infusion were reported 27 times in 17 patients. Fatigue was the most commonly reported health complaint (in 9.5% of patients). Four health complaints were judged to be IARs and reported to the Erasmus MC University Medical Center. None of the IARs reported in this study warranted emergency clinical care.ConclusionsOur data demonstrate that home-based ERT in Pompe disease can be safely implemented as few, mostly mild, symptoms were reported during or after infusion. Insights from this study can be used as a base for implementing home-based ERT in other countries and to further optimize patient care, as unreported mild symptoms do not pose a health risk but may still be relevant to the patient.

VP.29 Safety analysis of home-based enzyme replacement therapy with alglucosidase alfa in Pompe disease; a prospective study

Pompe disease is a progressive lysosomal storage disease treated with life-long weekly or biweekly enzyme replacement therapy (ERT). Home-based ERT diminishes the burden of treatment in Pompe patients and has been provided in the Netherlands since 2008. The COVID-19 pandemic has prompted the need for home-based ERT. We conducted a prospective survey to map infusion associated reactions (IARs) and validate safety of home-based ERT during one year. Patients with Pompe disease currently receiving alglucosidase alfa infusions at home were included. Prospective data on the occurrence, severity and management of IARs related to the home-infusion of alglucosidase alfa were collected by means of questionnaires. Patients received this questionnaire every three months during one year. Data on 120 patients were collected; 18 classic infantile, 18 childhood onset, and 84 adult onset Pompe patients. In total 116 of these patients filled in 423 questionnaires (overall response rate: 88%). Health problems during or within 48 hours from infusion were reported 27 times in 17 patients (5 classic infantile, 1 childhood onset, 11 adult onset). None of the infusion associated reactions that occurred warranted immediate care in hospital. Our data demonstrate that home-based ERT in Pompe disease is safe as few IARs occurred and those that occurred could be managed with no or minor interventions. Insights gained from this study can be used as a base for implementation of home-infusions in other countries and for further optimization of the protocol for home-based therapy with ERT in Pompe disease.

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.

Immunological challenges and approaches to immunomodulation in Pompe disease: a literature review.

Pompe disease is an autosomal recessive disorder caused by a deficiency of acid alpha-glucosidase resulting in intralysosomal glycogen accumulation in multiple tissue types, especially cardiac, skeletal, and smooth muscle. Enzyme replacement therapy (ERT) with alglucosidase alfa has led to improved clinical outcomes and prolonged survival in patients with Pompe disease. While ERT has changed the natural course of Pompe disease, with many long-term survivors, several factors affect the response to ERT. Previous studies in Pompe disease have shown that IgG antibodies to ERT can lead to a decline in muscle strength, pulmonary function, and overall and ventilator-free survival. Additionally, antibody responses to ERT can also cause hypersensitivity reactions. Various strategies to prevent or eliminate the IgG antibody response have been attempted in patients with Pompe disease. A detailed literature search was performed to compile data regarding the consequences of IgG antibodies, clinical approaches to prevent or eliminate IgG antibodies in patients with Pompe disease, and to expand our understanding of new modalities being developed in non-clinical settings. All qualifying articles describing the impact of IgG antibodies on the response to ERT, immunomodulation in patients with Pompe disease, and non-clinical settings identified via a PubMed database search were included in the review. Here, we provide a comprehensive review of combination- and single-agent therapies that have been investigated in the context of immune tolerance induction to ERT in Pompe disease to date. Immunomodulation strategies that successfully induce immune tolerance to ERT have improved overall survival, especially reflected in the decreased number of ventilator-dependent or deceased cross-reactive immunologic material (CRIM)-negative infantile Pompe disease (IPD) patients due to development of IgG antibodies when treated with ERT alone. Immunomodulation in CRIM-positive patients at the time they receive ERT also results in a decrease in the development of IgG antibodies compared to cases treated with ERT alone. Lessons learned from current approaches, alongside results from trials of novel immunomodulation strategies, may provide important insights into the development of next-generation therapies.

Production of recombinant human acid α-glucosidase with high-mannose glycans in gnt1 rice for the treatment of Pompe disease

Lysosomal storage diseases are a group of inherited metabolic disorders. Patients are treated with enzyme replacement therapy (ERT), in which the replacement enzymes are required to carry terminal mannose or mannose 6-phosphate residues to allow efficient uptake into target cells and tissues. N-acetylglucosaminyltransferase-I (GnTI) mediates N-glycosylation in the cis cisternae of the Golgi apparatus by adding N-acetylglucosamine to the exposed terminal mannose residue of core N-glycan structures for further processing. Mutant rice lacking GnTI produces only high mannosylated glycoproteins. In this study, we introduced a gene encoding recombinant human acid α-glucosidase (rhGAA), which is used in ERT for Pompe disease, into gnt1 rice callus by particle bombardment. Integration of the target gene into the genome of the gnt1 rice line and its mRNA expression were confirmed by PCR and Northern blot, respectively. Western blot analysis was performed to confirm secretion of the target proteins into the culture media. Using an indirect enzyme linked immunosorbent assay, we determined the maximum expression of rhGAA to be approximately 45mg/L, 13days after induction. To assay the enzymatic activity and determine the N-glycan profile of rhGAA, we purified the protein using a 6×histidine tag. The in vitro α-glucosidase activity of rhGAA from gnt1 rice callus (gnt1-GAA) was 3.092U/mg, similar to the activity of the Chinese hamster ovary cell-derived GAA (3.154U/mg). N-glycan analysis revealed the presence of high-mannose N-glycans on gnt1-GAA. In addition, the production of high-mannose GAA using gnt1 rice calli as an expression host was characterized, which may aid the future development of therapeutic enzymes for the treatment of Pompe disease.

Durable and sustained immune tolerance to ERT in Pompe disease with entrenched immune responses.

Enzyme replacement therapy (ERT) has prolonged survival and improved clinical outcomes in patients with infantile Pompe disease (IPD), a rapidly progressive neuromuscular disorder. Yet marked interindividual variability in response to ERT, primarily attributable to the development of antibodies to ERT, remains an ongoing challenge. Immune tolerance to ongoing ERT has yet to be described in the setting of an entrenched immune response. Three infantile Pompe patients who developed high and sustained rhGAA IgG antibody titers (HSAT) and received a bortezomib-based immune tolerance induction (ITI) regimen were included in the study and were followed longitudinally to monitor the long-term safety and efficacy. A trial to taper the ITI protocol was attempted to monitor if true immune tolerance was achieved. Bortezomib-based ITI protocol was safely tolerated and led to a significant decline in rhGAA antibody titers with concomitant sustained clinical improvement. Two of the 3 IPD patients were successfully weaned off all ITI protocol medications and continue to maintain low/no antibody titers. ITI protocol was significantly tapered in the third IPD patient. B cell recovery was observed in all 3 IPD patients. This is the first report to our knowledge on successful induction of long-term immune tolerance in patients with IPD and HSAT refractory to agents such as cyclophosphamide, rituximab, and methotrexate, based on an approach using the proteasome inhibitor bortezomib. As immune responses limit the efficacy and cost-effectiveness of therapy for many conditions, proteasome inhibitors may have new therapeutic applications. This research was supported by a grant from the Genzyme Corporation, a Sanofi Company (Cambridge, Massachusetts, USA), and in part by the Lysosomal Disease Network, a part of NIH Rare Diseases Clinical Research Network (RDCRN).

Long-Term Interruption of Enzyme Replacement Therapy with rhGAA in Pompe Disease Leads to Irreversible Clinical Decline

Enzyme replacement therapy (ERT) with recombinant human alglucosidase alfa (rhGAA) in Pompe disease is moderately effective and a life-long therapy is warranted. Clinical investigations of temporary ERT interruption are lacking, but might be of clinical signifi cance (i.e. due to patient’s wish, adherence issues, holidays, or problems with drug supply). In Switzerland, ERT for Pompe disease was interrupted after the federal court judged that the treatment costs for adults were greatly out of proportion. Retreatment was initiated after therapy was fi nally licensed.

Cessation and resuming of alglucosidase alfa in Pompe disease: a retrospective analysis.

Enzyme replacement therapy (ERT) with recombinant human alglucosidase alfa (rhGAA) in late-onset Pompe disease is moderately effective. Little is known about the clinical course after treatment termination and the resumption of ERT. In Switzerland, rhGAA therapy for Pompe disease was temporarily withdrawn after the federal court judged that the treatment costs were greatly out of proportion compared to the benefits. Re-treatment was initiated after the therapy was finally licensed. We retrospectively analysed seven Pompe patients, who underwent cessation and resumption of ERT (median age 43years). The delay from first symptoms to final diagnosis ranged from 4 to 20years. The demographics, clinical characteristics, assessments with the 6-min walking test (6-MWT), the predicted forced vital capacity (FVC) and muscle strength were analysed. Before initiation of ERT, all patients suffered from proximal muscle weakness of the lower limbs; one was wheelchair-bound and two patients received night-time non-invasive ventilation. Initial treatment stabilised respiratory function in most patients and improved their walking performance. After treatment cessation, upright FVC declined in most and the 6-MWT declined in all patients. Two patients needed additional non-invasive ventilatory support. Twelve months after resuming ERT, the respiratory and walking capacity improved again in most patients. However, aside for one patient, none of the patients reached the same level of respiratory function or distance walked in 6min, as at the time of ERT withdrawal. We conclude that cessation of ERT in Pompe disease causes a decline in clinical function and should be avoided. Resuming treatment only partially recovers respiratory function and walking capacity.

Immune responses and hypercoagulation in ERT for Pompe disease are mutation and rhGAA dose dependent.

Enzyme replacement therapy (ERT) with recombinant human acid-α-glucosidase (rhGAA) is the only FDA approved therapy for Pompe disease. Without ERT, severely affected individuals (early onset) succumb to the disease within 2 years of life. A spectrum of disease severity and progression exists depending upon the type of mutation in the GAA gene (GAA), which in turn determines the amount of defective protein produced and its enzymatic activity. A large percent of the early onset patients are also cross reactive immunological material negative (CRIM-) and develop high titer immune responses to ERT with rhGAA. New insights from our studies in pre-clinical murine models reveal that the type of Gaa mutation has a profound effect on the immune responses mounted against ERT and the associated toxicities, including activation of clotting factors and disseminated intravascular coagulation (DIC). Additionally, the mouse strain affects outcomes, suggesting the influence of additional genetic components or modifiers. High doses of rhGAA (20 mg/kg) are currently required to achieve therapeutic benefit. Our studies indicate that lower enzyme doses reduce the antibody responses to rhGAA, reduce the incidence of immune toxicity and avoid ERT-associated anaphylaxis. Therefore, development of rhGAA with increased efficacy is warranted to limit immunotoxicities.

Lysosomal storage diseases: Stem cell-based cell- and gene-therapy.

Lysosomal storage diseases (LSDs) are caused by inborn genetic defects and most affected babies show pathology in the CNS. LSDs are caused by a specific inherited enzyme deficiency that results in accumulation of substrates in the lysosomes, distension of the organelles and subsequent cellular malfunction. Currently, no effective treatment is available for most of the LSDs, because the blood?brain barrier bars entry of enzyme preparations into the brain. Treatment for LSDs can be divided into those address symptoms or those address cause. At present, successful treatments for the LSDs are enzyme replacement therapy (ERT) and cell therapy. ERT is most successful in Gaucher disease and has been approved for Fabry disease, and mucopolysaccharidosis I (MPS I). In addition, ERT for Pompe disease, MPS II, MPS VI and MPS VII has been planned and awaiting approval for treatment. Limitations in ERT include need for life-long treatment, development of antibodies, and inability to cross blood brain barrier (BBB) resulting in failure to halt disease progression in the brain. Transplantation of hematopoietic stem cells (HSCs), bone marrow stem cells (BMSCs) and umbilical cord blood-derived stem cells (UCBSCs) offer effective but limited efficacy for patients suffering from Krabbe disease, MPS VII and adrenal leukodystrophy but in other LSDs they are ineffective. Intracranial/intracerebral transplantation of genetically modified stem cells as enzyme delivery system could bypass the BBB effectively and ensure release of therapeutically beneficial amount of enzymes to affected CNS lesion sites. For this reason, stem cell-based gene therapy is the most effective treatment for LSDs. In mouse models of LSDs, genetically modified neural stem cells encoding enzyme genes effectively decreased lysosomal storage, reduced pathology and extended life span of animals. Cell-based gene therapies for LSDs bridge the application of ERT and gene therapy and are important direction to pursue in the future.

Aerobic training as an adjunctive therapy to enzyme replacement in Pompe disease

BackgroundAerobic exercise may be used in conjunction with enzyme replacement therapy (ERT) to attenuate cardiovascular deconditioning, skeletal muscle wasting, and loss of motor function in Pompe disease (glycogen storage disease type II; GSDII), but the effects on lysosomal glycogen content and macroautophagy have not been defined to date. PurposeThe main objectives of this study were to determine if acute aerobic exercise enhances 24-h uptake of recombinant human enzyme (rhGAA; Myozyme® [aim 1]) and if endurance training improves disease pathology when combined with ERT [aim 2] in Pompe mice. MethodsFor the first aim in our study, Pompe mutant mice (6neo/6neo) were grouped into ERT (Myozyme® injection only [40mg/kg]) and ERT+EX (Myozyme® injection followed by 90min treadmill exercise) cohorts, and enzyme uptake was assessed in the heart and quadriceps 24h post injection. For the second aim of our study, mutant mice were randomized into control, endurance-trained, enzyme-treated, or combination therapy groups. Exercised animals underwent 14weeks of progressive treadmill training with or without biweekly Myozyme® injections (40mg/kg) and tissues were harvested 1week post last treatment. ResultsMyozyme® uptake (GAA activity) was not improved in ERT+EX over ERT alone at 24-h post injection. Endurance exercise training, with or without ERT, improved aerobic capacity and normalized grip strength, motor function, and lean mass (P<0.05), but did not reduce glycogen content or normalize macroautophagy beyond traditional enzyme replacement therapy. ConclusionsEndurance training is beneficial as an adjunctive therapy to ERT in Pompe disease, although it works by mechanisms independent of a reduction in glycogen content.

β2 Agonists enhance the efficacy of simultaneous enzyme replacement therapy in murine Pompe disease

Enzyme replacement therapy (ERT) with recombinant human acid α-glucosidase (rhGAA) has improved clinical outcomes in patients with Pompe disease; however, the response of skeletal muscle and the central nervous system to ERT has been attenuated. The poor response of skeletal muscle to ERT has been attributed to the low abundance of the cation-independent mannose-6-phosphate receptor (CI-MPR), which mediates receptor-mediated uptake of rhGAA. Hence the ability of adjunctive therapy with β2-agonists to increase CI-MPR expression in skeletal muscle was evaluated during ERT in murine Pompe disease with regard to reversal of neuromuscular involvement. Mice with Pompe disease were treated with weekly rhGAA injections (20 mg/kg) and a selective β2-agonist, either albuterol (30 mg/l in drinking water) or low-dose clenbuterol (6 mg/l in drinking water). Biochemical correction was enhanced by β2-agonist treatment in both muscle and the cerebellum, indicating that adjunctive therapy could enhance efficacy from ERT in Pompe disease with regard to neuromuscular involvement. Intriguingly, clenbuterol slightly reduced muscle glycogen content independent of CI-MPR expression, as demonstrated in CI-MPR knockout/GAA knockout mice that were otherwise resistant to ERT. Thus, adjunctive therapy with β2 agonists might improve the efficacy of ERT in Pompe disease and possibly other lysosomal storage disorders through enhancing receptor-mediated uptake of recombinant lysosomal enzymes.

Enzyme-Replacement Therapy for Pompe Disease

Pompe disease (α-glucosidase deficiency; also known as glycogen storage disease type II) is the first lysosomal storage disorder for which the biochemical basis was determined. Development of enzyme-replacement therapy for Pompe disease initially involved competing commercial interests and clinical trials using two different enzyme formulations, including one derived from transgenic rabbit’s milk. Further studies have since been conducted with the enzyme generated from transduction of Chinese hamster ovary cells. Therapeutic benefits have been observed in treated patients with either the infantile or late-onset form of Pompe disease; clinical subtypes with marked differences in clinical course and survival. Several factors, including disease duration and antibody formation, appear to influence clinical outcome of enzyme-replacement therapy. Recently, defects of autophagy have been demonstrated; these changes may represent a separate target for therapeutic intervention to optimize outcome. Meanwhile, issues that require further investigation include pathogenesis, ways to improve the means of targeting of recombinant enzyme to skeletal muscle, means to facilitate an early diagnosis and the benefit of early intervention, particularly for the late-onset forms of the disease. Moreover, other therapeutic strategies, such as the use of pharmacologic chaperone and gene therapy, are under investigation.

Abstract 4396: Clinical Response to Recombinant Acid α-Glucosidase is Predicted by Cardiac Outcome Measures in Children with Pompe Disease

Background : Pompe disease is an autosomal-recessive glycogen storage disease due to deficiency of acid α-glucosidase (GAA). Clinical findings in infantile onset disease are due to glycogen accumulation leading to hypertrophic cardiomyopathy, skeletal myopathy, respiratory failure and death. Enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA; Myozyme®) has been shown to prolong survival in infants. We assessed the hypothesis that myocardial response to rhGAA predicts clinical outcome in Pompe. Methods: Echos during one year of ERT were reviewed from patients enrolled in open label trials of rhGAA (n=38). A standardized echo protocol was used at specific time points (wks 0, 4, 8, 12, 26, 38, 52). A central reader made measurements off-line, blinded to study information. Variables including LV mass, volumes, and ejection fraction (EF) were determined. Clinical outcomes at study-end were analyzed in 2 groups: Group A, alive and free of assisted ventilation (AV) or Group B, died or requiring AV. Z-scores were calculated for all echo variables and median z-scores between outcome groups at wk 0 and wk 52 were compared using median scores tests. Non-linear random effects models were used to examine changes over time. Results: Mean age at first infusion = 10.9±9.8 months (range 1.2 – 43.1). At study onset, 7/38 received AV. At study end, mean time to last infusion = 115±44 weeks with 16/38 in Group A and 22/38 in Group B. For Group A vs. Group B, median z-scores at week 0 for LV mass = 6.11 vs. 7.41, mass to volume ratio (MVR) = 4.5 vs. 8.8, and EF = 0.8 for both groups; p≥ 0.12 for each measure. Median z-scores for the same outcome groups, respectively, at week 52 for LV mass = 0.57 vs. 3.41 (p=0.06), for MVR = 0.48 vs. 3.54 (p=0.001) and EF = −0.6 in both groups. In the subgroup not requiring AV at study onset (n=31), MVR is higher at all times in Group B (p≤ 0.03). Conclusion: rhGAA therapy can prolong life in young patients with Pompe, improving outcome compared to an untreated natural history cohort. Even with ERT, there is significant morbidity and mortality. Diminished myocardial response with persistence of significant LV hypertrophy predicts progression to poor clinical outcomes. These and other predictors are required to fully understand response to ERT in Pompe disease.

Glucose tetrasaccharide as a biomarker for monitoring the therapeutic response to enzyme replacement therapy for Pompe disease

A tetraglucose oligomer, Glcα1-6Glcα1-4Glcα1-4Glc, designated Glc 4, has been shown to be a putative biomarker for the diagnosis of Pompe disease. The purpose of this study was to assess whether Glc 4 could be used to monitor the therapeutic response to recombinant human acid α glucosidase (rhGAA) enzyme replacement therapy (ERT) in patients with Pompe disease. Urinary Glc 4 levels in 11 patients receiving rhGAA therapy was determined by both HPLC-UV and stable isotope dilution ESI-MS/MS. Combined Glc 4 and maltotetraose, Glcα1-4Glcα1-4Glcα1-4Glc, (M 4) concentrations, designated Hex 4, in plasma from these patients were measured by HPLC-UV only. Baseline urinary Glc 4 and plasma Hex 4 in these patients (mean ± SD: 34.2 ± 11.3 mmol/mol creatinine and 1.7 ± 0.8 μM, respectively) were higher than age-matched control values (mean ± SD, 6.1 ± 5.1 mmol/mol creatinine and 0.22 ± 0.15 μM, respectively). Both urinary Glc 4 and plasma Hex 4 levels decreased after initiation of ERT for all patients. In the four patients with the best overall clinical response in both skeletal and cardiac muscle, levels decreased to within, or near, normal levels during the first year of treatment. In contrast, levels fluctuated and were persistently elevated above the control ranges in those patients with a less favorable clinical response (good cardiac response but limited motor improvement). These results suggest that urinary Glc 4 and plasma Hex 4 could serve as a valuable adjunct to clinical endpoints for monitoring the efficacy of therapeutic interventions such as rhGAA ERT in Pompe disease.