David Ketteridge

Direct Comparison of Measures of Endurance, Mobility, and Joint Function During Enzyme-Replacement Therapy of Mucopolysaccharidosis VI (Maroteaux-Lamy Syndrome): Results After 48 Weeks in a Phase 2 Open-Label Clinical Study of Recombinant Human N-Acetylgalactosamine 4-Sulfatase

Objective. Mucopolysaccharidosis VI (MPS VI; Maroteaux-Lamy syndrome) is a lysosomal storage disease caused by a deficiency of the enzyme N-acetylgalactosamine 4-sulfatase (ASB). This enzyme deficiency leads to a progressive disorder with multiple tissue and organ involvement. The disease is rare and is heterogeneous in its clinical presentation and progression. A potential treatment for this disease exists in the form of enzyme-replacement therapy (ERT) with recombinant human ASB (rhASB), and a phase 1/2 randomized, double-blind, 2-dose (0.2 and 1 mg/kg) study in 6 patients showed the treatment at 48 weeks to be well tolerated. Greater biochemical efficacy based on a urine glycosaminoglycan occurred in the high-dose (1 mg/kg) group, and functional improvement seemed greater in patients in the high-dose group with rapidly advancing disease. On the basis of the phase 1/2 results, a phase 2, open-label study in patients with rapidly advancing disease was initiated primarily to evaluate efficacy variables that measure endurance, mobility, and joint function in a larger group of patients. Methods. This was an open-label, multinational study of 10 MPS VI patients who received 48 weekly intravenous treatments with 1.0 mg/kg rhASB and had assessments of biochemical and clinical responses at regular intervals. Results. After 24 weeks of treatment, each patient on average experienced a 155-m (98%) improvement in the 12-minute walk, a 64-m (62%) improvement at the 6-minute time point of the 12-minute walk, and a 48-stair (110%) gain in the 3-minute stair climb versus the baseline mean values. Additional improvements after 48 weeks of treatment were observed, including mean values of 211 m (138%) in the 12-minute walk, 75 m (80%) at the 6-minute time point of the 12-minute walk, and 61-stair (147%) gain in the 3-minute stair climb versus the baseline mean values. Joint Pain and Stiffness Questionnaire scores improved by at least 50% by week 24 and were maintained at week 48, whereas there were only small improvements in active shoulder range of motion (<10°) and in the time taken to stand, walk, and turn starting from a seated position (Expanded Timed Get-Up and Go test). Improvement in pulmonary function based on forced vital capacity and forced expiratory volume at 1 minute in the absence of growth was observed in 3 of 6 patients, and the observed gains occurred in the 24- to 48-week treatment interval. A mean decrease of 76% in urinary excretion of glycosaminoglycans indicated that a satisfactory biochemical response was achieved and the ERT was well tolerated. Conclusions. The results suggest that a 12-minute walk extends the dynamic range of the conventional 6-minute walk and, along with the 3-minute stair climb, provide a robust approach to documenting the improvement in endurance in MPS VI patients who undergo ERT with rhASB.

Long-term follow-up of endurance and safety outcomes during enzyme replacement therapy for mucopolysaccharidosis VI: Final results of three clinical studies of recombinant human N-acetylgalactosamine 4-sulfatase

UNLABELLED The objective of this study was to evaluate the long-term clinical benefits and safety of recombinant human arylsulfatase B (rhASB) treatment of mucopolysaccharidosis type VI (MPS VI: Maroteaux-Lamy syndrome), a lysosomal storage disease. Fifty-six patients derived from 3 clinical studies were followed in open-label extension studies for a total period of 97-260 Weeks. All patients received weekly infusions of rhASB at 1 mg/kg. Efficacy was evaluated by (1) distance walked in a 12-minute walk test (12MWT) or 6-minute walk test (6MWT), (2) stairs climbed in the 3-minute stair climb (3MSC), and (3) reduction in urinary glycosaminoglycans (GAG). Safety was evaluated by compliance, adverse event (AE) reporting and adherence to treatment. RESULTS A significant reduction in urinary GAG (71-79%) was sustained. For the 12MWT, subjects in Phase 2 showed improvement of 255+/-191 m (mean+/-SD) at Week 144; those in Phase 3 Extension demonstrated improvement from study baseline of 183+/-26 m (mean+/- SE) in the rhASB/rhASB group at Week 96 and from treatment baseline (Week 24) of 117+/-25 m in the placebo/rhASB group. The Phase 1/2 6MWT and the 3MSC from Phase 2 and 3 also showed sustained improvements through the final study measurements. Compliance was 98% overall. Only 560 of 4121 reported AEs (14%) were related to treatment with only 10 of 560 (2%) described as severe. CONCLUSION rhASB treatment up to 5 years results in sustained improvements in endurance and has an acceptable safety profile.

Mutations of the mitochondrial ND1 gene as a cause of MELAS

Complex I is the largest of the mitochondrial respiratory chain enzyme complexes, consisting of at least 46 subunits, seven of which are encoded by mtDNA. Deficiency of complex I is the most common respiratory chain defect, and can be caused by mutations in both nuclear and mtDNA encoded genes. It has a wide range of clinical presentations, from lethal infantile mitochondrial disease to isolated myopathy.1–3 Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is one of the syndromes associated with complex I deficiency and in approximately 80% of cases is caused by a mutation, 3243A→G, in the mitochondrial tRNALeu(UUR) gene ( MTTL1 ). Other mutations in MTTL1 and other transfer RNA genes ( MTTF , MTTV , MTTQ ) account for most of the remainder of cases.4 However, a number of mutations in the mitochondrial MTND subunit genes of complex I have also been reported to cause MELAS, most notably in MTND5 5 and to a lesser extent in MTND6 .6 In stark contrast, there are presently no mutations in the MTND1 subunit gene associated with MELAS. There are several mutations in MTND1 associated with Leber’s hereditary optic neuropathy (LHON) which may be pathogenic, but only one, the 3460G→A mutation, that has robust evidence, including cell biology studies, for pathogenicity.7–9 Here we report three unrelated patients with MELAS and isolated complex I deficiency in skeletal muscle and cultured fibroblasts due to previously unreported mutations in the MTND1 gene. Evidence confirming the pathogenic nature of these mutations includes data from cell fusion experiments and blue native polyacrylamide gel electrophoresis (BN-PAGE), the latter confirming a crucial role for the ND1 subunit in the assembly of complex I holoenzyme.10 ### Patient 1 Patient 1, a white male, presented at 4 years of age with a 3 month history of increasing tiredness, clumsiness, …

Threshold effect of urinary glycosaminoglycans and the walk test as indicators of disease progression in a survey of subjects with Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome).

A cross‐sectional survey in individuals affected with the lysosomal storage disease Mucopolysaccharidosis VI (MPS VI) was conducted to establish demographics, urinary glycosaminoglycan (GAG) levels, and clinical progression of the disease. The survey evaluated 121 bona fide MPS VI‐affected individuals over the age of 4 years from 15 countries across the Americas, Europe, and Australasia representing greater than 10% of the estimated world prevalence of the disease. A medical history, complete physical exam, urinary GAG determination, and assessment of several clinical measures related to physical endurance, pulmonary function, joint range of motion, strength, and quality of life were completed for each participant. Although a wide variation in clinical presentation was observed, several general findings were obtained reflecting progression of the disease. Impaired physical endurance, as measured by the distance achieved in a 6‐min walk, could be demonstrated across all age groups of MPS VI‐affected individuals. High urinary GAG values (>200 μg/mg creatinine) were associated with an accelerated clinical course comprised of age‐adjusted short stature and low body weight, impaired endurance, compromised pulmonary function, and reduced joint range of motion. An unexpected result was the predominance of urinary GAG values <100 μg/mg creatinine for those participants over the age of 20 years. Pending the collection of longitudinal data, these results suggest that urinary GAG levels predict clinical morbidity, and longer‐term survival is associated with urinary GAG levels below a threshold of 100 μg/mg creatinine.

Enzyme replacement therapy for mucopolysaccharidosis VI: Growth and pubertal development in patients treated with recombinant human N-acetylgalactosamine 4-sulfatase

BACKGROUND AND METHODS: Growth failure is characteristic of untreated mucopolysaccharidosis type VI (MPS VI: Maroteaux-Lamy syndrome). Growth was studied in fifty-six MPS VI patients (5 to 29 years old) prior to and for up to 240 weeks of weekly infusions of recombinant human arylsulfatase B (rhASB) at 1 mg/kg during Phase 1/2, Phase 2, Phase 3 or Phase 3 Extension clinical trials. Height, weight, and Tanner stage data were collected. Pooled data were analyzed to determine mean height increase by treatment week, growth impacts of pubertal status, baseline urinary GAG, and age at treatment initiation. Growth rate for approximately 2 years prior to and following treatment initiation was analyzed using longitudinal modeling. RESULTS: Mean height increased by 2.9 cm after 48 weeks and 4.3 cm after 96 weeks on enzyme replacement therapy (ERT). Growth on ERT was not correlated with baseline urinary GAG. Patients under 16 years of age showed greatest increases in height on treatment. Model results based on pooled data showed significant improvement in growth rate during 96 weeks of ERT when compared to the equivalent pretreatment time period. Delayed pubertal onset or progression was noted in 10 patients entering the clinical trials; all of whom showed progression of at least one Tanner stage during 2 years on ERT, and 6 of whom (60%) completed puberty. CONCLUSION: Analysis of mean height by treatment week and longitudinal modeling demonstrate significant increase in height and growth rate in MPS VI patients receiving long-term ERT. This impact was greatest in patients aged below 16 years. Height increase may result from bone growth and/or reduction in joint contractures. Bone growth and resolution of delayed puberty may be related to improvements in general health, bone cell health, nutrition, endocrine gland function and reduced inflammation.

Diagnosing mucopolysaccharidosis IVA

Mucopolysaccharidosis IVA (MPS IVA; Morquio A syndrome) is an autosomal recessive lysosomal storage disorder resulting from a deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS) activity. Diagnosis can be challenging and requires agreement of clinical, radiographic, and laboratory findings. A group of biochemical genetics laboratory directors and clinicians involved in the diagnosis of MPS IVA, convened by BioMarin Pharmaceutical Inc., met to develop recommendations for diagnosis. The following conclusions were reached. Due to the wide variation and subtleties of radiographic findings, imaging of multiple body regions is recommended. Urinary glycosaminoglycan analysis is particularly problematic for MPS IVA and it is strongly recommended to proceed to enzyme activity testing even if urine appears normal when there is clinical suspicion of MPS IVA. Enzyme activity testing of GALNS is essential in diagnosing MPS IVA. Additional analyses to confirm sample integrity and rule out MPS IVB, multiple sulfatase deficiency, and mucolipidoses types II/III are critical as part of enzyme activity testing. Leukocytes or cultured dermal fibroblasts are strongly recommended for enzyme activity testing to confirm screening results. Molecular testing may also be used to confirm the diagnosis in many patients. However, two known or probable causative mutations may not be identified in all cases of MPS IVA. A diagnostic testing algorithm is presented which attempts to streamline this complex testing process.

Dietary L-tyrosine supplementation in nemaline myopathy.

Nemaline myopathy is defined by the presence of nemaline bodies, or rods, on muscle biopsy. Facial and bulbar weakness in nemaline myopathy cause chewing and swallowing difficulties, recurrent aspiration, and poor control of oral secretions. This article discusses 5 patients (4 infants and 1 adolescent) with nemaline myopathy who received dietary supplementation with L-tyrosine (250 to 3000 mg/day). All 4 infants were reported to have an initial decrease in sialorrhoea and an increase in energy levels. The adolescent showed improved strength and exercise tolerance. No adverse effects of treatment were observed. Dietary tyrosine supplementation may improve bulbar function, activity levels, and exercise tolerance in nemaline myopathy.

Natural history and galsulfase treatment in mucopolysaccharidosis VI (MPS VI, Maroteaux–Lamy syndrome)—10-year follow-up of patients who previously participated in an MPS VI survey study†

Mucopolysaccharidosis VI (MPS VI) is a clinically heterogeneous and progressive disorder with multiorgan manifestations caused by deficient N‐acetylgalactosamine‐4‐sulfatase activity. A cross‐sectional Survey Study in individuals (n = 121) affected with MPS VI was conducted between 2001 and 2002 to establish demographics, urinary glycosaminoglycan (GAG) levels, and clinical progression of disease. We conducted a Resurvey Study (ClinicalTrials.gov: NCT01387854) to obtain 10‐year follow‐up data, including medical histories and clinical assessments (n = 59), and survival status over 12 years (n = 117). Patients received a mean (SD) of 6.8 (2.2) years of galsulfase ERT between baseline (Survey Study) and follow‐up. ERT patients increased in height by 20.4 cm in the 4–7‐year‐old baseline age group and by 16.8 cm in the 8–12‐year‐old baseline age group. ERT patients <13 years‐old demonstrated improvement in forced vital capacity (FVC) by 68% and forced expiratory volume in 1 sec (FEV1) by 55%, and those ≥13 years‐old increased FVC by 12.8% and maintained FEV1. Patients with >200 µg/mg baseline uGAG levels increased FVC by 48% in the <13‐year‐old baseline age group and by 15% in the ≥13‐year‐old baseline age group. ERT patients who completed the 6‐min walk test demonstrated a mean (SD) increase of 65.7 (100.6) m. Cardiac outcomes did not significantly improve or worsen. Observed mortality rate among naïve patients was 50% (7/14) and 16.5% (17/103) in the ERT group (unadjusted hazard ratio, 0.24; 95% CI, 0.10–0.59). Long‐term galsulfase ERT was associated with improvements in pulmonary function and endurance, stabilized cardiac function and increased survival.

Expert recommendations for the laboratory diagnosis of MPS VI.

Mucopolysaccharidosis VI (MPS VI) is a lysosomal storage disease caused by a deficiency of N-acetylgalactosamine 4-sulfatase (arylsulfatase B, ASB). This enzyme is required for the degradation of dermatan sulfate. In its absence, dermatan sulfate accumulates in cells and is excreted in large quantities in urine. Specific therapeutic intervention is available; however, accurate and timely diagnosis is crucial for maximal benefit. To better understand the current practices for diagnosis and to establish diagnostic guidelines, an international MPS VI laboratory diagnostics scientific summit was held in February of 2011 in Miami, Florida. The various steps in the diagnosis of MPS VI were discussed including urinary glycosaminoglycan (uGAG) analysis, enzyme activity analysis, and molecular analysis. The following conclusions were reached. Dilute urine samples pose a significant problem for uGAG analysis and MPS VI patients can be missed by quantitative uGAG testing alone as dermatan sulfate may not always be excreted in large quantities. Enzyme activity analysis is universally acknowledged as a key component of diagnosis; however, several caveats must be considered and the appropriate use of reference enzymes is essential. Molecular analysis supports enzyme activity test results and is essential for carrier testing, subsequent genetic counseling, and prenatal testing. Overall the expert panel recommends caution in the use of uGAG screening alone to rule out or confirm the diagnosis of MPS VI and acknowledges enzyme activity analysis as a critical component of diagnosis. Measurement of another sulfatase enzyme to exclude multiple sulfatase deficiency was recommended prior to the initiation of therapy. When feasible, the use of molecular testing as part of the diagnosis is encouraged. A diagnostic algorithm for MPS VI is provided.

An overview of intra-articular therapy for mucopolysaccharidosis VI

Dyane Auclaira,∗, David Ketteridgeb, Stephanie Oatesb, John J. Hopwooda and Sharon Byersc Lysosomal Diseases Research Unit, SA Pathology (at Women’s and Children’s Hospital), North Adelaide, SA, Australia Metabolic unit, SA Pathology (at Women’s and Children’s Hospital), North Adelaide, SA, Australia Matrix Biology Unit, SA Pathology (at Women’s and Children’s Hospital), North Adelaide, SA, Australia