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

Long-term observation of patients with advanced late-onset Pompe disease undergoing enzyme replacement therapy: A 15-year observation in a single center

BACKGROUND

There have been few descriptions in the literature on long-term enzyme replacement therapy (ERT) in patients with advanced late-onset Pompe disease (LOPD).

OBJECTIVES

This study aimed to assess the efficacy and limitations of ERT in advanced LOPD patients.

METHODS

We retrospectively reviewed the clinical courses of patients with advanced LOPD (two juvenile-onset and five adult-onset patients) who were treated with recombinant human alglucosidase alfa to examine improvements achieved with and limitations of ERT until their death or when switching to avalglucosidase alfa occurred.

RESULTS

All patients were non-ambulant and ventilator dependent. The duration of follow-up ranged from 3.7 to 15.0 years (median 9.0 years). All patients reported improvements in their lives during the first two or three years of ERT. Vital capacity was clearly improved in patients with relatively spared respiratory function, although it deteriorated after respiratory complications such as pneumothorax. Pinch and grip power tended to be preserved during the treatment period. Muscle CT revealed progression of atrophy and fatty replacement predominantly in the proximal limb muscles without improvement after ERT. Four patients died due to aspergillosis, respiratory failure, ileus, and sudden death of unknown cause.

CONCLUSIONS

Our findings demonstrate that patients undergoing ERT show certain improvements, even in the advanced stage of Pompe disease. Respiratory complications are lethal even during ERT, and early diagnosis and induction of therapy are critical. Muscle wasting progressed more severely in the proximal limbs, even after ERT.

Comparing the efficacy of cipaglucosidase alfa plus miglustat with other enzyme replacement therapies for late-onset Pompe disease: a network meta-analysis utilizing patient-level and aggregate data

Aim: Late-onset Pompe disease is characterized by progressive loss of muscular and respiratory function. Until recently, standard of care was enzyme replacement therapy (ERT) with alglucosidase alfa. Second-generation ERTs avalglucosidase alfa (aval) and cipaglucosidase alfa with miglustat (cipa+mig) are now available. Without head-to-head trials comparing aval with cipa+mig, an indirect treatment comparison is informative and timely for understanding potential clinical differentiation. Materials & methods: A systematic literature review was performed to identify relevant studies on cipa+mig and aval. Using patient-level and aggregate published data from randomized controlled trials (RCTs) and phase I/II and open-label extension (OLE) trials, a multi-level network meta-regression was conducted, adjusting for various baseline covariates, including previous ERT duration, to obtain relative effect estimates on 6-minute walk distance (6MWD, meters [m]) and forced vital capacity (FVC, % predicted [pp]). Analyses of two networks were conducted: Network A, including only RCTs, and network B, additionally including single-arm OLE and phase I/II studies. Results: Network B (full evidence analysis) showed that cipa+mig was associated with a relative increase in 6MWD (mean difference 28.93 m, 95% credible interval [8.26-50.11 m]; Bayesian probability 99.7%) and FVC (2.88 pp [1.07-4.71 pp]; >99.9%) compared with aval. The comparison between cipa+mig and aval became more favorable for cipa+mig with increasing previous ERT duration for both end points. Analysis of network A showed that cipa+mig was associated with a relative decrease in 6MWD (-10.02 m [-23.62 to 4.00 m]; 91.8%) and FVC (-1.45 pp [-3.01 to 0.07 pp]; 96.8%) compared with aval. Conclusion: Cipa+mig showed a favorable effect versus aval when all available evidence was used in the analysis.

The Importance of Early Treatment of Inherited Neuromuscular Conditions

There has been tremendous progress in treatment of neuromuscular diseases over the last 20 years, which has transformed the natural history of these severely debilitating conditions. Although the factors that determine the response to therapy are many and in some instance remain to be fully elucidated, early treatment clearly has a major impact on patient outcomes across a number of inherited neuromuscular conditions. To improve patient care and outcomes, clinicians should be aware of neuromuscular conditions that require prompt treatment initiation. This review describes data that underscore the importance of early treatment of children with inherited neuromuscular conditions with an emphasis on data resulting from newborn screening efforts.

Pompe Disease: a Clinical, Diagnostic, and Therapeutic Overview

Purpose of Review

This review summarizes the clinical presentation and provides an update on the current strategies for diagnosis of Pompe disease. We will review the available treatment options. We examine newly approved treatments as well as upcoming therapies in this condition. We also provide commentary on the unmet needs in clinical management and research for this disease.

Recent Findings

In March 2015, Pompe disease was added to the Recommended Uniform Screening Panel (RUSP) and since then a number of states have added Pompe disease to their slate of diseases for their Newborn Screening (NBS) program. Data emerging from these programs is revising our knowledge of incidence of Pompe disease. In 2021, two randomized controlled trials involving new forms of enzyme replacement therapy (ERT) were completed and one new product is already FDA-approved and on the market, whereas the other product will come up for FDA review in the fall. Neither of the new ERT were shown to be superior to the standard of care product, alglucosidase. The long-term effectiveness of these newer forms of ERT is unclear. Newer versions of the ERT are in development in addition to multiple different strategies of gene therapy to deliver GAA, the gene responsible for producing acid alpha-glucosidase, the defective protein in Pompe Disease. Glycogen substrate reduction is also in development in Pompe disease and other glycogen storage disorders.

Summary

There are significant unmet needs as it relates to clinical care and therapeutics in Pompe disease as well as in research. The currently available treatments lose effectiveness over the long run and do not have penetration into neuronal tissues and inconsistent penetration in certain muscles. More definitive gene therapy and enzyme replacement strategies are currently in development and testing.

Outcome of Later-Onset Pompe Disease Identified Through Newborn Screening

OBJECTIVE

To determine the outcomes of patients with later-onset Pompe disease (LOPD) identified through newborn screening (NBS).

STUDY DESIGN

A prospective observational cohort study was conducted from the initiation of Pompe disease NBS by following subjects every 3-12 months for motor development and biochemical markers.

RESULTS

Between 2005 and 2018, 39 of 994 975 newborns evaluated were classified as having LOPD based on low acid α-glucosidase (GAA) activity but no cardiac involvement at the time of screening. As of December 2020, 8 of these 39 infants (21%) were treated with enzyme replacement therapy owing to persistent elevation of creatine kinase (CK), cardiac involvement, or developmental delay. All subjects' physical performance and endurance improved after treatment. Subjects carrying c.[752C>T;761C>T] and c.[546+5G>T; 1726G>A] presented a phenotype of nonprogressive hypotonia, muscle weakness, and impairment in physical fitness tests, but they have not received treatment.

CONCLUSIONS

One-fifth of subjects identified through NBS as having LOPD developed symptoms after a follow-up of up to 15 years. NBS was found to facilitate the early detection and early treatment of those subjects. GAA variants c.[752C>T;761C>T] and c.[546+5G>T; 1726G>A] might not cause Pompe disease but still may affect skeletal muscle function.

Bioimpedance Phase Angle as a Prognostic Tool in Late-Onset Pompe Disease: A Single-Centre Prospective Study With a 15-year Follow-Up

Background: Late-onset Pompe disease (LOPD) is an autosomal-recessive metabolic myopathy caused by deficiency of the lysosomal enzyme Acid Alpha—Glucosidase (GAA), leading to glycogen accumulation in proximal and axial muscles, and in the diaphragm. Enzyme Replacement Therapy (ERT) with recombinant GAA became available in 2006. Since then, several outcome measures have been investigated for the adequate follow-up of disease progression and treatment response, usually focusing on respiratory and motor function. Prognostic factors predicting outcome have not been identified till now.

Methods: In this single Centre, prospective study, we evaluate the response to enzyme replacement therapy in 15 patients (7 males) with LOPD in different stages of disease, aged 49.4 ± 16.1, followed-up for 15 years. Treatment response was measured by the 6-min walking test, vital capacity in supine and upright position, respiratory muscle strength, muscle MRI, manual muscle testing. We investigated the usefulness of Body Impedance Vectorial Analysis for serial body composition assessment.

Results: Although most patients with LOPD benefit from long-term treatment, some secondary decline may occur after the first 3–5 years. Some nutritional (lower body mass index, higher fat free mass, higher phase angle) and disease parameters (higher creatinine and shorter disease duration at the beginning of treatment) seem to predict a better motor outcome. Lower Phase Angle, possibly reflecting loss of integrity of skeletal muscle membranes and thus treatment mis-targeting, seems to correlate with worse treatment response on long-term follow-up.

Conclusion: Body Impedance Vectorial Analysis is a fast, easily performed and cheap tool that may be able to predict long-term treatment response in patients with LOPD. Low Phase angle may serve as a marker of muscle quality and may be used to predict the response to a muscle-targeted intervention such as ERT, thus improving the identification of patients needing a closer follow-up due to higher fragility and risk of deterioration.

Safety and efficacy of cipaglucosidase alfa plus miglustat versus alglucosidase alfa plus placebo in late-onset Pompe disease (PROPEL): an international, randomised, double-blind, parallel-group, phase 3 trial

BACKGROUND

Pompe disease is a rare disorder characterised by progressive loss of muscle and respiratory function due to acid α-glucosidase deficiency. Enzyme replacement therapy with recombinant human acid α-glucosidase, alglucosidase alfa, is the first approved treatment for the disease, but some patients do not respond, and many do not show a sustained benefit. We aimed to assess the safety and efficacy of an investigational two-component therapy (cipaglucosidase alfa, a novel recombinant human acid α-glucosidase, plus miglustat, an enzyme stabiliser) for late-onset Pompe disease.

METHODS

We did a randomised, double-blind, parallel-group, phase 3 trial at 62 neuromuscular and metabolic medical centres in 24 countries in the Americas, Asia-Pacific, and Europe. Eligible participants were aged 18 years or older with late-onset Pompe disease, and had either been receiving alglucosidase alfa for at least 2 years or were enzyme replacement therapy-naive. Participants were randomly assigned (2:1) using interactive response technology software, stratified by 6-min walk distance and previous enzyme replacement therapy status, to intravenous cipaglucosidase alfa (20 mg/kg) plus oral miglustat or to intravenous alglucosidase alfa (20 mg/kg) plus oral placebo once every 2 weeks for 52 weeks. Patients, investigators, and outcome assessors were masked to treatment assignment. The primary endpoint was change from baseline to week 52 in 6-min walk distance, assessed using a mixed-effect model for repeated measures analysis for comparison of superiority in the intention-to-treat population (all patients who received at least one dose of study drug). This study is now complete and is registered with ClinicalTrials.gov, NCT03729362.

FINDINGS

Between Dec 3, 2018, and Nov 26, 2019, 130 patients were screened for eligibility and 125 were enrolled and randomly assigned to receive cipaglucosidase alfa plus miglustat (n=85) or alglucosidase alfa plus placebo (n=40). Two patients in the alglucosidase alfa plus placebo group did not receive any dose due to absence of genotype confirmation of late-onset Pompe disease and were excluded from analysis. Six patients discontinued (one in the alglucosidase alfa plus placebo group, five in the cipaglucosidase alfa plus miglustat group), and 117 completed the study. At week 52, mean change from baseline in 6-min walk distance was 20·8 m (SE 4·6) in the cipaglucosidase alfa plus miglustat group versus 7·2 m (6·6) in the alglucosidase alfa plus placebo group using last observation carried forward (between-group difference 13·6 m [95% CI -2·8 to 29·9]). 118 (96%) of 123 patients experienced at least one treatment-emergent adverse event during the study; the incidence was similar between the cipaglucosidase alfa plus miglustat group (n=81 [95%]) and the alglucosidase alfa plus placebo group (n=37 [97%]). The most frequently reported treatment-emergent adverse events were fall (25 [29%] patients in the cipaglucosidase alfa plus miglustat group vs 15 [39%] in the alglucosidase alfa plus placebo group), headache (20 [24%] vs 9 [24%]), nasopharyngitis (19 [22%] vs 3 [8%]), myalgia (14 [16%] vs 5 [13%]), and arthralgia (13 [15%]) vs 5 [13%]). 12 serious adverse events occurred in eight patients in the cipaglucosidase alfa plus miglustat group; only one event (anaphylaxis) was deemed related to study drug. One serious adverse event (stroke) occurred in the alglucosidase alfa plus placebo group, which was deemed unrelated to study drug. There were no deaths.

INTERPRETATION

Cipaglucosidase alfa plus miglustat did not achieve statistical superiority to alglucosidase alfa plus placebo for improving 6-min walk distance in our overall population of patients with late-onset Pompe disease. Further studies should investigate the longer-term safety and efficacy of cipaglucosidase alfa plus miglustat and whether this investigational two-component therapy might provide benefits, particularly in respiratory function and in patients who have been receiving enzyme replacement therapy for more than 2 years, as suggested by our secondary and subgroup analyses.

FUNDING

Amicus Therapeutics.

Hypoventilation syndrome in neuromuscular disorders

PURPOSE OF REVIEW

Hypoventilation syndrome in neuromuscular disorders (NMDs) is primarily due to respiratory muscle weakness and results in increased morbidity and mortality. This article highlights current aspects of neuromuscular hypoventilation syndrome, including pathophysiology, clinical symptoms, assessment, respiratory involvement in various NMD, and causal and symptomatic treatments with an emphasis on recent research and advances.

RECENT FINDINGS AND SUMMARY

New therapeutic agents have been developed within the last years, proving a positive effect on respiratory system. Symptomatic therapies, including mechanical ventilation and cough assistance approaches, are important in NMD and respiratory muscle training may have benefit in strengthening respiratory muscles and should be offered patients with respiratory muscle weakness the same way as physiotherapy. Correct respiratory assessments and their correct interpretation are hallmarks for early diagnosis of hypoventilation syndrome and treatment.