Gastrointestinal symptoms in late-onset Pompe disease: Early response to enzyme replacement therapy

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

BACKGROUND

Pompe 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.

METHODS

All 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.

RESULTS

In 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.

CONCLUSIONS

Our 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.

Gut dysmotility in children with neurological impairment: the nutritional management

Intestinal motility disorders represent a frequent problem in children with neurological impairment. These conditions are characterized by abnormal movements of the gut, which can result in symptoms such as constipation, diarrhea, reflux, and vomiting. The underlying mechanisms leading to dysmotility are various, and the clinical manifestations are often nonspecific. Nutritional management is an important aspect of care for children with gut dysmotility, as it can help to improve their quality of life. Oral feeding, when safe and in the absence of risk of ingestion or severe dysphagia, should always be encouraged. When oral nutrition is insufficient or potentially harmful, it is necessary to switch to an enteral by tube or parenteral nutrition before the onset of malnutrition. In most cases, children with severe gut dysmotility may require feeding via a permanent gastrostomy tube to ensure adequate nutrition and hydration. Drugs may be necessary to help manage gut dysmotility, such as laxatives, anticholinergics and prokinetic agents. Nutritional management of patients with neurological impairment often requires an individualized care plan to optimize growth and nutrition and to improve overall health outcomes. This review tries to sum up most significant neurogenetic and neurometabolic disorders associated with gut dysmotility that may require a specific multidisciplinary care, identifying a proposal of nutritional and medical management.

New Insights into Gastrointestinal Involvement in Late-Onset Pompe Disease: Lessons Learned from Bench and Bedside

BACKGROUND

There are new emerging phenotypes in Pompe disease, and studies on smooth muscle pathology are limited. Gastrointestinal (GI) manifestations are poorly understood and underreported in Pompe disease.

METHODS

To understand the extent and the effects of enzyme replacement therapy (ERT; alglucosidase alfa) in Pompe disease, we studied the histopathology (entire GI tract) in Pompe mice (GAAKO 6^neo/6^neo). To determine the disease burden in patients with late-onset Pompe disease (LOPD), we used Patient-Reported Outcomes Measurements Information System (PROMIS)-GI symptom scales and a GI-focused medical history.

RESULTS

Pompe mice showed early, extensive, and progressive glycogen accumulation throughout the GI tract. Long-term ERT (6 months) was more effective to clear the glycogen accumulation than short-term ERT (5 weeks). GI manifestations were highly prevalent and severe, presented early in life, and were not fully amenable to ERT in patients with LOPD (n = 58; age range: 18-79 years, median age: 51.55 years; 35 females; 53 on ERT).

CONCLUSION

GI manifestations cause a significant disease burden on adults with LOPD, and should be evaluated during routine clinical visits, using quantitative tools (PROMIS-GI measures). The study also highlights the need for next generation therapies for Pompe disease that target the smooth muscles.

Nutrition in adult patients with selected lysosomal storage diseases

Lysosomal storage disorders (LSDs) are a group of clinically heterogeneous disorders affecting the function of lysosomes and are characterized by an accumulation of undigested substrates within several cell types. In recent years there have been substantial advances in supportive care and drug treatment for some LSDs, leading to improved patient survival, as seen in Gaucher, Pompe and Fabry disease and some Mucopolysaccharidoses; however, many symptoms still persist. Thus it is now even more important to improve patients' quality of life and reduce symptoms and comorbidities. One potential way of achieving this goal is through adjunct nutritional therapy, which is challenging as patients may be overweight with associated consequences, or malnourished, or underweight. Furthermore, drugs used to treat LSDs can modify the metabolic status and needs of patients. There are currently not enough data to make specific dietary recommendations for individual LSDs; however, suggestions can be made for managing clinical manifestations of the diseases, as well as treatment-associated adverse events. The metabolic and nutritional status of adult patients must be regularly assessed and individualized dietary plans may be created to cater to a patient's specific needs. Damage to the autophagic process is a common feature in LSDs that is potentially sensitive to dietary manipulation and needs to be assessed in clinical studies.

Glycogen accumulation in smooth muscle of a Pompe disease mouse model

Pompe disease is a lysosomal storage disease caused by mutations within the GAA gene, which encodes acid α-glucosidase (GAA)—an enzyme necessary for lysosomal glycogen degradation. A lack of GAA results in an accumulation of glycogen in cardiac and skeletal muscle, as well as in motor neurons. The only FDA approved treatment for Pompe disease—an enzyme replacement therapy (ERT)—increases survival of patients, but has unmasked previously unrecognized clinical manifestations of Pompe disease. These clinical signs and symptoms include tracheo-bronchomalacia, vascular aneurysms, and gastro-intestinal discomfort. Together, these previously unrecognized pathologies indicate that GAA-deficiency impacts smooth muscle in addition to skeletal and cardiac muscle. Thus, we sought to characterize smooth muscle pathology in the airway, vascular, gastrointestinal, and genitourinary in the Gaa^−/− mouse model. Increased levels of glycogen were present in smooth muscle cells of the aorta, trachea, esophagus, stomach, and bladder of Gaa^−/− mice, compared to wild type mice. In addition, there was an increased abundance of both lysosome membrane protein (LAMP1) and autophagosome membrane protein (LC3) indicating vacuolar accumulation in several tissues. Taken together, we show that GAA deficiency results in subsequent pathology in smooth muscle cells, which may lead to life-threatening complications if not properly treated.

Multisystem late onset Pompe disease (LOPD): an update on clinical aspects

Pompe disease is classified by age of onset, organ involvement, severity, and rate of progression in two main forms: the first one, infantile onset Pompe disease (IOPD), presents before the age of 12 months with generalized muscle weakness, hypotonia, respiratory distress, and hypertrophic cardiomyopathy as main clinical features. The second form, late onset Pompe disease (LOPD), is characterized by an onset at the age of 12 months to adulthood, hyperCKemia, and limb-girdle and axial muscle weakness, often complicated by respiratory muscles degeneration. In the last 10-15 years, an increasing interest in Pompe disease has led to multiple studies in an effort to clarify the emerging clinical aspects, to find out the best diagnostic tools to identify the disease as early as possible, and to offer new therapeutic options apart from enzyme replacement therapy (ERT). Since 2006, ERT-the first treatment for Pompe disease-has been universally accepted in the majority of countries all over the world. Although for years Pompe disease has been primarily considered a muscle disorder, nowadays it is clear that the involvement of several other organs has changed the cultural approach to this entity which is now viewed as a multisystem disorder. The emerging clinical aspects have greatly expanded the spectrum of the disease manifestations. In fact, central, peripheral, and autonomous nervous systems are often involved; vascular malformations and heart involvement are frequently observed; musculoskeletal and bone changes as well as oro-gastrointestinal and urinary tract alterations have been better defined. A great deal of effort has been made to clarify the clinical aspects of Pompe disease, to raise awareness of the LOPD patients' problems and to improve their quality of life.

The impact of Pompe disease on smooth muscle: a review

Pompe disease (OMIM 232300) is an autosomal recessive disorder caused by mutations in the gene encoding acid α-glucosidase (GAA) (EC 3.2.1.20), the enzyme responsible for hydrolyzing lysosomal glycogen. The primary cellular pathology is lysosomal glycogen accumulation in cardiac muscle, skeletal muscle, and motor neurons, which ultimately results in cardiorespiratory failure. However, the severity of pathology and its impact on clinical outcomes are poorly described in smooth muscle. The advent of enzyme replacement therapy (ERT) in 2006 has improved clinical outcomes in infantile-onset Pompe disease patients. Although ERT increases patient life expectancy and ventilator free survival, it is not entirely curative. Persistent motor neuron pathology and weakness of respiratory muscles, including airway smooth muscles, contribute to the need for mechanical ventilation by some patients on ERT. Some patients on ERT continue to experience life-threatening pathology to vascular smooth muscle, such as aneurysms or dissections within the aorta and cerebral arteries. Better characterization of the disease impact on smooth muscle will inform treatment development and help anticipate later complications. This review summarizes the published knowledge of smooth muscle pathology associated with Pompe disease in animal models and in patients.

Improvement of bone mineral density after enzyme replacement therapy in Chinese late-onset Pompe disease patients

Objective

Late-onset Pompe disease (LOPD) is a lysosomal storage disease resulted from deficiency of the enzyme acid α-glucosidase. Patients usually develop a limb-girdle pattern of myopathy and respiratory impairment, and enzyme replacement therapy (ERT) is the only specific treatment available. Recently, LOPD has been associated with low bone mineral density (BMD), but the effect of ERT on BMD is inconclusive. In this report we described our early observations on the change of BMD after ERT in Chinese LOPD patients.

Results

We studied four Chinese LOPD patients with different severities of myopathy. All were underweight, and three had osteoporosis at baseline. We found significant weight gain in three patients after ERT and all four patients showed improvement in BMD. The biggest improvement, 84.4% increase in BMD, was seen in a lady with the most prominent weight recovery. Our results suggest that ERT improves BMD in Chinese LOPD and weight gain could be a major contributor to this effect.

The emerging phenotype of late-onset Pompe disease: A systematic literature review

BACKGROUND

Pompe disease is an autosomal recessive disorder caused by deficiency of the lysosomal glycogen-hydrolyzing enzyme acid α-glucosidase (GAA). The adult-onset form, late-onset Pompe disease (LOPD), has been characterized by glycogen accumulation primarily in skeletal, cardiac, and smooth muscles, causing weakness of the proximal limb girdle and respiratory muscles. However, increased scientific study of LOPD continues to enhance understanding of an evolving phenotype.

PURPOSE

To expand our understanding of the evolving phenotype of LOPD since the approval of enzyme replacement therapy (ERT) with alglucosidase alfa (Myozyme™/Lumizyme™) in 2006.

METHODS

All articles were included in the review that provided data on the charactertistics of LOPD identified via the PubMed database published since the approval of ERT in 2006. All signs and symptoms of the disease that were reported in the literature were identified and included in the review.

RESULTS

We provide a comprehensive review of the evolving phenotype of LOPD. Our findings support and extend the knowledge of the multisystemic nature of the disease.

CONCLUSIONS

With the advent of ERT and the concurrent increase in the scientific study of LOPD, the condition once primarily conceptualized as a limb-girdle muscle disease with prominent respiratory involvement is increasingly recognized to be a condition that results in signs and symptoms across body systems and structures.