Enzyme replacement therapy with alglucosidase alfa in Pompe disease: Clinical experience with rate escalation

Long-Term Outcome of Infantile Onset Pompe Disease Patients Treated with Enzyme Replacement Therapy - Data from a German-Austrian Cohort

BACKGROUND

Enzyme replacement therapy (ERT) with recombinant human alglucosidase alfa (rhGAA) was approved in Europe in 2006. Nevertheless, data on the long-term outcome of infantile onset Pompe disease (IOPD) patients at school age is still limited.

OBJECTIVE

We analyzed in detail cardiac, respiratory, motor, and cognitive function of 15 German-speaking patients aged 7 and older who started ERT at a median age of 5 months.

RESULTS

Starting dose was 20 mg/kg biweekly in 12 patients, 20 mg/kg weekly in 2, and 40 mg/kg weekly in one patient. CRIM-status was positive in 13 patients (86.7%) and negative or unknown in one patient each (6.7%). Three patients (20%) received immunomodulation. Median age at last assessment was 9.1 (7.0-19.5) years. At last follow-up 1 patient (6.7%) had mild cardiac hypertrophy, 6 (42.9%) had cardiac arrhythmias, and 7 (46.7%) required assisted ventilation. Seven patients (46.7%) achieved the ability to walk independently and 5 (33.3%) were still ambulatory at last follow-up. Six patients (40%) were able to sit without support, while the remaining 4 (26.7%) were tetraplegic. Eleven patients underwent cognitive testing (Culture Fair Intelligence Test), while 4 were unable to meet the requirements for cognitive testing. Intelligence quotients (IQs) ranged from normal (IQ 117, 102, 96, 94) in 4 patients (36.4%) to mild developmental delay (IQ 81) in one patient (9.1%) to intellectual disability (IQ 69, 63, 61, 3x <55) in 6 patients (54.5%). White matter abnormalities were present in 10 out of 12 cerebral MRIs from 7 patients.

CONCLUSION

Substantial motor, cardiac, respiratory, and cognitive deficits are frequent in IOPD long-term survivors who started ERT before 2016. The findings of this study can be valuable as comparative data when evaluating the impact of newer treatment strategies including higher enzyme dosage, immunomodulation, modified enzymes, or early start of treatment following newborn screening.

Clinical and Genetic Aspects of Juvenile Onset Pompe Disease

Little is known about clinical symptomatology and genetics of juvenile onset Pompe disease (JOPD). The aims of this study were to analyze how these children are diagnosed, what clinical problems they have, and how phenotype is related to genotype. To accomplish this, we analyzed retrospectively data of 34 patients diagnosed after their first and before completion of their 18th birthday. Median age at diagnosis was 3.9 (range 1.1-17) years. Eight patients (23.5%) developed initial symptoms in the first year, 12 (35%) between 1 and 7 years, and 6 (18%) thereafter. Eight (23.5%) had no clinical symptoms at the time of diagnosis. Indications for diagnostics were a positive family history in three (9%), hyperCKemia in eight (23.5%), motor developmental delay in three (9%), and muscle weakness and/or pain in 17 (50%). Rare clinical signs were failure to thrive, recurrent diarrhea, and suspected hepatopathy with glycogen storage. Thirty-two different mutations were identified. Twenty-seven patients (79.5%) carried the milder c.32-13T > G mutation, known to be associated with a broad range of phenotypes. Three out of eight patients manifesting within the first year of life showed generalized muscle weakness, hypertrophic cardiomyopathy, and had to be ventilated during the course of disease, thereby demonstrating clinical overlap with infantile onset Pompe disease.These findings demonstrate that the phenotype of JOPD is broad and that the differential is not only restricted to neuromuscular disorders. Genotypic analysis was useful to delineate subjects with early onset JOPD from those with IOPD, but overall genotype-phenotype correlation was poor.

To detect potential pathways and target genes in infantile Pompe patients using computational analysis

Introduction: Pompe disease (PD) is a disease caused by pathogenic variations in the GAA gene known as glycogen storage disease type II, characterized by heart hypertrophy, respiratory failure, and muscle hypotonia, leading to premature death if not treated early. The only treatment option, enzyme replacement therapy (ERT), significantly improves the prognosis for some patients while failing to help others. In this study, the determination of key genes involved in the response to ERT and potential molecular mechanisms were investigated.

Methods: Gene Expression Omnibus (GEO) data, accession number GSE38680, containing samples of biceps and quadriceps muscles was used. Expression array data were analyzed using BRB-Array Tools. Biceps group patients did not receive ERT, while quadriceps received treatment with rhGAA at 0, 12, and 52 weeks. Differentially expressed genes (DEGs) were deeply analyzed by DAVID, GO, KEGG and STRING online analyses, respectively.

Results: A total of 1727 genes in the biceps group and 1198 genes in the quadriceps group are expressed differently. It was observed that DEGs were enriched in the group that responded poorly to ERT in the 52nd week. Genes frequently changed in the weak response group; the expression of 530 genes increased and 1245 genes decreased compared to 0 and 12 weeks. The GO analysis demonstrated that the DEGs were mainly involved in vascular smooth muscle contraction, lysosomes, autophagy, regulation of actin cytoskeleton, inflammatory response, and the WNT signaling pathway. We also discovered that the WNT signaling pathway is highly correlated with DEGs. Several DEGs, such as WNT11, WNT5A, CTNNB1, M6PR, MYL12A, VCL, TLN, FYN, YES1, and BCL2, may be important in elucidating the mechanisms underlying poor response to ERT.

Conclusion: Early diagnosis and treatment of PD are very important for the clinic of the disease. As a result, it suggests that the enriched genes and new pathways emerging as a result of the analysis may help identify the group that responds poorly to treatment and the outcome of the treatment. Obtained genes and pathways in neonatal screening will guide diagnosis and treatment.

Hepatic expression of GAA results in enhanced enzyme bioavailability in mice and non-human primates

Pompe disease (PD) is a severe neuromuscular disorder caused by deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). PD is currently treated with enzyme replacement therapy (ERT) with intravenous infusions of recombinant human GAA (rhGAA). Although the introduction of ERT represents a breakthrough in the management of PD, the approach suffers from several shortcomings. Here, we developed a mouse model of PD to compare the efficacy of hepatic gene transfer with adeno-associated virus (AAV) vectors expressing secretable GAA with long-term ERT. Liver expression of GAA results in enhanced pharmacokinetics and uptake of the enzyme in peripheral tissues compared to ERT. Combination of gene transfer with pharmacological chaperones boosts GAA bioavailability, resulting in improved rescue of the PD phenotype. Scale-up of hepatic gene transfer to non-human primates also successfully results in enzyme secretion in blood and uptake in key target tissues, supporting the ongoing clinical translation of the approach.

Stepwise shortening of agalsidase beta infusion duration in Fabry disease: Clinical experience with infusion rate escalation protocol

Background

Although enzyme replacement therapy with agalsidase beta resulted in a variety of clinical benefits, life‐long biweekly intravenous infusion may impact on patients’ quality of life. Moreover, regular infusions are time‐consuming: although a stepwise shortening of infusion duration is allowed up to a minimum of 1.5 hr, in most centers it remains ≥3 hr, and no data exists about the safety and tolerability of agalsidase beta administration at maximum tolerated infusion rate.

Methods

In this study, we reported our experience with a stepwise infusion rate escalation protocol developed in our center in a cohort of 53 Fabry patients (both already receiving and treatment‐naΪve), and explored factors predictive for the infusion rate increase tolerability.

Results

Fifty‐two patients (98%) reduced infusion duration ≤3 hr; of these, 38 (72%) even reached a duration ≤2 hr. We found a significant difference between the mean duration reached by already treated and naΪve patients (p < .01). More severely affected patients (male patients and those with lower enzyme activity) received longer infusions for higher risk of infusion‐associated reactions (IARs). A significant correlation between anti‐agalsidase antibodies and IARs was found.

Conclusion

Our infusion rate escalation protocol is safe and could improve patient compliance, satisfaction and quality of life.

Gene Therapy for Pompe Disease: The Time is now

Pompe disease (PD) is caused by the deficiency of the lysosomal enzyme acid α-glucosidase (GAA), resulting in systemic pathological glycogen accumulation. PD can present with cardiac, skeletal muscle, and central nervous system manifestations, as a continuum of phenotypes among two main forms: classical infantile-onset PD (IOPD) and late-onset PD (LOPD). IOPD is caused by severe GAA deficiency and presents at birth with cardiac hypertrophy, muscle hypotonia, and severe respiratory impairment, leading to premature death, if not treated. LOPD is characterized by levels of residual GAA activity up to ∼20% of normal and presents both in children and adults with a varied severity of muscle weakness and motor and respiratory deficit. Enzyme replacement therapy (ERT), based on repeated intravenous (i.v.) infusions of recombinant human GAA (rhGAA), represents the only available treatment for PD. Upon more than 10 years from its launch, it is becoming evident that ERT can extend the life span of IOPD and stabilize disease progression in LOPD; however, it does not represent a cure for PD. The limited uptake of the enzyme in key affected tissues and the high immunogenicity of rhGAA are some of the hurdles that limit ERT efficacy. GAA gene transfer with adeno-associated virus (AAV) vectors has been shown to reduce glycogen storage and improve the PD phenotype in preclinical studies following different approaches. Here, we present an overview of the different gene therapy approaches for PD, focusing on in vivo gene transfer with AAV vectors and discussing the potential opportunities and challenges in developing safe and effective gene therapies for the disease. Based on emerging safety and efficacy data from clinical trials for other protein deficiencies, in vivo gene therapy with AAV vectors appears to have the potential to provide a therapeutically relevant, stable source of GAA enzyme, which could be highly beneficial in PD.

Long-term outcome and unmet needs in infantile-onset Pompe disease

Infantile-onset Pompe disease (IOPD) is characterized by virtually complete absence of acid alpha-glucosidase (GAA)-activity, resulting in rapidly progressive hypertrophic cardiomyopathy (HCM), profound skeletal muscle weakness, and death usually within the first 12 months of life. Enzyme replacement therapy (ERT) with recombinant GAA in humans started in 1999, and pivotal studies demonstrated that the treatment ameliorated HCM, improved motor function in some patients, and prolonged overall and ventilator-free survival. These outcomes led to the approval of ERT in 2006. Implementation of ERT has uncovered multisystemic character of IOPD, not known in the pre-ERT era. Although ERT has substantially improved the prognosis of IOPD, mortality is still considerable, and decline of motor function with time is frequent in long-term survivors. This review details the new complex IOPD phenotype, outlines problems related to ERT, and highlights unmet needs.

Improvement in Cardiac Function With Enzyme Replacement Therapy in a Patient With Infantile-Onset Pompe Disease

Background

Pompe disease is a lysosomal storage disorder that results from an inborn error of metabolism involving abnormal glycogen storage. Infantile-onset Pompe disease is the most severe phenotype, and enzyme replacement therapy with alglucosidase alfa (Lumizyme) improves medical and functional outcomes in patients with infantile-onset Pompe disease.

Case Report

We report the case of a patient with infantile-onset Pompe disease who presented with severe hypertrophic cardiomyopathy, systolic and diastolic cardiac dysfunction, and hypotonia. She experienced significant improvement in cardiac systolic function while receiving enzyme replacement therapy.

Conclusion

Typically, patients with infantile-onset Pompe disease and severe hypertrophic cardiomyopathy are not as responsive to enzyme replacement therapy as patients with mild or no hypertrophic cardiomyopathy. We demonstrated the efficacy of enzyme replacement therapy in a patient with severe hypertrophic cardiomyopathy.

Early higher dosage of alglucosidase alpha in classic Pompe disease

Background With conventional enzyme replacement therapy (ERT), the clinical prognosis of classic Pompe disease is often unsatisfactory. About half the patients treated with ERT at the recommended dosage (20 mg/kg every other week) require ventilatory support within the first years of life. The heterogeneous response to ERT has been related to different factors, including cross-reactive immunologic material (CRIM) status and age at ERT initiation. Early treatment with a standard dosage of ERT improves clinical outcome and avoids mechanical ventilation in CRIM-positive patients detected at newborn screening, not preventing persistent hyperCKemia and muscle weakness. Later treatment with higher dosages of ERT was shown to provide similar benefits in CRIM-positive patients. Here, we report the clinical and biochemical outcomes of six patients with classic Pompe disease treated with different dosages of alglucosidase alpha at different ages. Methods A standard dosage of ERT was employed in five patients, sharing a poor prognosis after transient clinical improvements, even in the case of early treatment (four died at 22.2±11.9 months and one survived but required tracheostomy and gastrostomy). Early higher dosage of alglucosidase alpha (40 mg/kg/week from 14 days) was administered to one CRIM-positive patient with fetal persistent bradycardia. Results Early higher dosage of alclucosidase alpha not only achieved normal neuromotor development but also the full correction of biochemical markers of muscle damage until 3 years of age, an unmet target with the standard dosage. Speech delay was not prevented by this approach. Conclusions We suggest that early treatment with a higher dosage of ERT may further improve clinical prognosis in classic Pompe disease.

[Research advances in the diagnosis and treatment of Pompe disease]

Pompe disease, also called type II glycogen storage disease, is a rare autosomal recessive inherited disease caused by the storage of glycogen in lysosome due to acid α-glucosidase (GAA) deficiency, with the most severe conditions in the skeletal muscle, the myocardium, and the smooth muscle. Patients may have the manifestations of dyspnea and dyskinesia, with or without hypertrophic cardiomyopathy. GAA gene mutation has ethnic and regional differences, and new mutation sites are found with the advances in research. Gene analysis is the gold standard for the diagnosis of Pompe disease. Conventional methods, such as skin and muscle biopsies and dried blood spot test, have certain limitations for the diagnosis of this disease. In recent years, prenatal diagnosis and newborn screening play an important role in early diagnosis of this disease. Enzyme replacement therapy (ERT) has a satisfactory effect in the treatment of this disease, but it may lead to immune intolerance. New targeted gene therapy and modified ERT will be put into practice in the future. This article reviews the research advances in the diagnosis and treatment of Pompe disease.

Pompe disease treatment with twice a week high dose alglucoside alfa in a patient with severe dilated cardiomyopathy

There is limited information regarding ideal dosage of alglucoside alfa in patients with Infantile Onset Pompe Disease (IOPD). The U.S. Food and Drug Administration approved alglucoside alfa at dosing of 20 mg/kg every other week, but there are small studies and case reports suggesting that dosing higher than this leads to improved ventilator free survival and development without adverse events. We review the clinical course and short term clinical outcomes one year following late diagnosis of IOPD in a 3 month old who presented severely affected and was treated with 40 mg/kg twice a week for 21 infusions until six months of age then transitioned to 40 mg/kg/week. The patient responded well to 40 mg/kg twice a week treatment without adverse reactions and significant clinical improvement.