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

Patients with Pompe disease have realized significant medical benefits due to enzyme replacement therapy (ERT) infusions with alglucosidase alfa. However, regular infusions are time-consuming. Utilizing recommended infusion rates, infusion duration is 3h 45min for a patient receiving the standard dose of 20mg/kg, not including additional time needed for preparation of ERT, assessment of vital signs, intravenous access, and post-infusion monitoring. Recent studies have demonstrated increased effectiveness of higher dose of ERT (40mg/kg) in infantile-onset Pompe disease (IOPD), which increases the infusion duration to 6h 36min. Increased infusion durations compound the psychosocial burden on patients and families and potentially further disrupt family activities and obligations. We developed a stepwise infusion rate escalation protocol to administer higher dose ERT safely while decreasing infusion duration, which has been implemented in 15 patients to date. Reported here in detail are five patients with IOPD on 40mg/kg/weekly ERT in whom infusion duration was decreased with individualized, stepwise rate escalation. All patients tolerated rate escalations above the recommended rates without experiencing any infusion associated reactions and experienced a reduction in infusion duration by 1h and 24min with a corresponding increase in reported satisfaction. Our experience with ERT rate escalation is presented. SYNOPSIS: A careful stepwise method of enzyme replacement therapy (ERT) rate escalation can safely reduce infusion duration in patients with Pompe disease.

Sensitivity of whole exome sequencing in detecting infantile- and late-onset Pompe disease.

Pompe disease is a metabolic myopathy with a wide spectrum of clinical presentation. The gold-standard diagnostic test is acid alpha-glucosidase assay on skin fibroblasts, muscle or blood. Identification of two GAA pathogenic variants in-trans is confirmatory. Optimal effectiveness of enzyme replacement therapy hinges on early diagnosis, which is challenging in late-onset form of the disease due to non-specific presentation. Next-generation sequencing-based panels effectively facilitate diagnosis, but the sensitivity of whole-exome sequencing (WES) in detecting pathogenic GAA variants remains unknown. We analyzed WES data from 93 patients with confirmed Pompe disease and GAA genotypes based on PCR/Sanger sequencing. After ensuring that the common intronic variant c.-32-13T>G is not filtered out, whole-exome sequencing identified both GAA pathogenic variants in 77/93 (83%) patients. However, one variant was missed in 14/93 (15%), and both variants were missed in 2/93 (2%). One complex indel leading to a severe phenotype was incorrectly called a nonsynonymous substitution c.-32-13T>C due to misalignment. These results demonstrate that WES may fail to diagnose Pompe disease. Clinicians need to be aware of limitations of WES, and consider tests specific to Pompe disease when WES does not provide a diagnosis in patients with proximal myopathy, progressive respiratory failure or other subtle symptoms.

Low anal sphincter tone in infantile-onset Pompe Disease: an emerging clinical issue in enzyme replacement therapy patients requiring special attention.

Pompe Disease (PD) is a lysosomal storage disease caused by acid α-glucosidase deficiency. The infantile form typically results in death in the first year of life. Patient survival has improved with enzyme replacement therapy (ERT), but new complications are being recognized. We report three cases of infantile onset PD on ERT who present with a new finding of poor anal tone, a finding that requires special attention for further complications such as rectal prolapse.

The emerging phenotype of long-term survivors with infantile Pompe disease.

PURPOSE: Enzyme replacement therapy with alglucosidase alfa for infantile Pompe disease has improved survival creating new management challenges. We describe an emerging phenotype in a retrospective review of long-term survivors. METHODS: Inclusion criteria included ventilator-free status and age ≤6 months at treatment initiation, and survival to age ≥5 years. Clinical outcome measures included invasive ventilator-free survival and parameters for cardiac, pulmonary, musculoskeletal, gross motor, and ambulatory status; growth; speech, hearing, and swallowing; and gastrointestinal and nutritional status. RESULTS: Eleven of 17 patients met study criteria. All were cross-reactive immunologic material-positive, alive, and invasive ventilator-free at most recent assessment, with a median age of 8.0 years (range: 5.4-12.0 years). All had marked improvements in cardiac parameters. Commonly present were gross motor weakness, motor speech deficits, sensorineural and/or conductive hearing loss, osteopenia, gastroesophageal reflux, and dysphagia with aspiration risk. Seven of 11 patients were independently ambulatory and four required the use of assistive ambulatory devices. All long-term survivors had low or undetectable anti-alglucosidase alfa antibody titers. CONCLUSION: Long-term survivors exhibited sustained improvements in cardiac parameters and gross motor function. Residual muscle weakness, hearing loss, risk for arrhythmias, hypernasal speech, dysphagia with risk for aspiration, and osteopenia were commonly observed findings.

Ectopic Ocular Surface Calcification in Patients With Hypophosphatasia Treated With Asfotase Alfa.

PURPOSE: To assess for ectopic ocular calcification in a series of patients with hypophosphatasia (HPP) treated with asfotase alfa, a recombinant tissue-nonspecific alkaline phosphatase. METHODS: This is a retrospective analysis of subjects enrolled at Duke University Medical Center in ENB-009-10 (ClinicalTrials.gov: NCT01163149), a randomized controlled trial of asfotase alfa in adolescents and adults with HPP. Seven patients between the ages of 45 and 66 years diagnosed with HPP based on clinical features and low serum alkaline phosphatase levels were enrolled at our site. Subjects were randomized to receive either daily subcutaneous injections of asfotase alfa or no treatment. After 24 weeks, during the open-label extension phase, all subjects received treatment for at least 4 years. All subjects underwent comprehensive eye examinations at baseline and at 24-week intervals throughout the study to assess for development of ocular calcifications. RESULTS: By week 120, all 7 subjects developed asymptomatic white refractile deposits in the interpalpebral perilimbal conjunctiva. Biopsy of the conjunctival lesions in 2 subjects revealed elastosis with subepithelial calcification. The lesions were nonprogressive and in 5 subjects exhibited some degree of regression. CONCLUSIONS: Asfotase alfa was invariably associated with development of mild focal conjunctival calcification, likely through disinhibition of hydroxyapatite crystal propagation. The calcifications were not symptomatic or vision-threatening and should not preclude enzyme replacement therapy for patients with this rare and often debilitating disease.

Improvement with ongoing Enzyme Replacement Therapy in advanced late-onset Pompe disease: a case study.

Benefits of enzyme replacement therapy with Myozyme (alglucosidase alfa), anecdotally reported in late-onset Pompe disease, range from motor and pulmonary improvement in less severely affected patients, to stabilization with minimal improvement in those with advanced disease. We report a case of a 63-year-old patient with significant morbidity who made notable motor and pulmonary function gains after two years on therapy. Thus, improvements in those with advanced disease may be possible after long-term treatment.

Corticobasal syndrome in a man with Gaucher disease type 1: Expansion of the understanding of the neurological spectrum.

Gaucher disease (GD) is an autosomal recessive condition that results from a deficiency of the enzyme ß-glucocerebrosidase. The increased risk of primary parkinsonism symptoms among individuals affected with GD and carriers for the disorder is well-documented in the literature. However, these risks and case reports often reflect patients with classical Parkinson's disease (PD) symptoms. We report a patient with GD type 1 who was diagnosed with corticobasal syndrome (CBS), a clinical atypical parkinsonism diagnosis, in his sixth decade of life. Our case highlights the need to consider forms of atypical parkinsonism such as CBS in addition to PD in the differential diagnosis of cognitive and motor changes in patients with GD type 1. We also recommend careful assessment and routine monitoring of cognition, mood, behavior, sleep patterns, olfaction, and memory in patients with GD type 1 to identify early symptoms indicative of neurological involvement.

Algorithm for the early diagnosis and treatment of patients with cross reactive immunologic material-negative classic infantile pompe disease: a step towards improving the efficacy of ERT.

OBJECTIVE: Although enzyme replacement therapy (ERT) is a highly effective therapy, CRIM-negative (CN) infantile Pompe disease (IPD) patients typically mount a strong immune response which abrogates the efficacy of ERT, resulting in clinical decline and death. This study was designed to demonstrate that immune tolerance induction (ITI) prevents or diminishes the development of antibody titers, resulting in a better clinical outcome compared to CN IPD patients treated with ERT monotherapy. METHODS: We evaluated the safety, efficacy and feasibility of a clinical algorithm designed to accurately identify CN IPD patients and minimize delays between CRIM status determination and initiation of an ITI regimen (combination of rituximab, methotrexate and IVIG) concurrent with ERT. Clinical and laboratory data including measures of efficacy analysis for response to ERT were analyzed and compared to CN IPD patients treated with ERT monotherapy. RESULTS: Seven CN IPD patients were identified and started on the ITI regimen concurrent with ERT. Median time from diagnosis of CN status to commencement of ERT and ITI was 0.5 months (range: 0.1-1.6 months). At baseline, all patients had significant cardiomyopathy and all but one required respiratory support. The ITI regimen was safely tolerated in all seven cases. Four patients never seroconverted and remained antibody-free. One patient died from respiratory failure. Two patients required another course of the ITI regimen. In addition to their clinical improvement, the antibody titers observed in these patients were much lower than those seen in ERT monotherapy treated CN patients. CONCLUSIONS: The ITI regimen appears safe and efficacious and holds promise in altering the natural history of CN IPD by increasing ERT efficacy. An algorithm such as this substantiates the benefits of accelerated diagnosis and management of CN IPD patients, thus, further supporting the importance of early identification and treatment initiation with newborn screening for IPD.

Cardiac arrhythmias following anesthesia induction in infantile-onset Pompe disease: a case series.

BACKGROUND: Patients with infantile-onset Pompe disease suffer from marked hypertrophic cardiomyopathy and an increased risk of arrhythmia. A noncompliant left ventricle predisposes these infants to diastolic heart failure with elevated left ventricular enddiastolic pressure (LVEDP); these patients also commonly develop systolic heart failure. Given this baseline cardiac physiology, coronary perfusion pressure becomes highly sensitive to abrupt changes in diastolic blood pressure (DBP). METHODS: We retrospectively reviewed the experiences of 139 patients enrolled in clinical trials investigating the treatment of infantile-onset Pompe disease with recombinant human acid alpha-glucosidase (rhGAA). Adverse events were screened for those involving anesthesia. RESULTS: Nine patients (6%) with infantile-onset Pompe disease experienced an arrhythmia or cardiopulmonary arrest soon after the induction of general anesthesia. Of these events, propofol was involved in four arrhythmias; sevoflurane without propofol was associated with an additional two. Deaths resulting from arrhythmia appeared to correlate with left ventricular mass indices >350 g x m(-2). CONCLUSIONS: With the advent of enzyme replacement therapy (ERT) using rhGAA, and increased survivability, more infantile Pompe patients will likely present for surgical procedures. Additional care in maximizing coronary perfusion pressure and minimizing arrhythmia risk must be given. For these reasons, it is recommended that anesthesia for infantile Pompe patients specifically avoid propofol or high concentrations of sevoflurane and, instead, use an agent such as ketamine as the cornerstone for induction in order to better support coronary perfusion pressure and to avoid decreasing DBP with vasodilatory agents.