Enzyme replacement therapy in mice lacking arylsulfatase B targets bone-remodeling cells, but not chondrocytes.

Mucopolysaccharidosis type VI (MPS-VI), caused by mutational inactivation of the glycosaminoglycan-degrading enzyme arylsulfatase B (Arsb), is a lysosomal storage disorder primarily affecting the skeleton. We have previously reported that Arsb-deficient mice display high trabecular bone mass and impaired skeletal growth. In the present study, we treated them by weekly injection of recombinant human ARSB (rhARSB) to analyze the impact of enzyme replacement therapy (ERT) on skeletal growth and bone remodeling. We found that all bone-remodeling abnormalities of Arsb-deficient mice were prevented by ERT, whereas chondrocyte defects were not. Likewise, histologic analysis of the surgically removed femoral head from an ERT-treated MPS-VI patient revealed that only chondrocytes were pathologically affected. Remarkably, a side-by-side comparison with other cell types demonstrated that chondrocytes have substantially reduced capacity to endocytose rhARSB, together with low expression of the mannose receptor. We finally took advantage of Arsb-deficient mice to establish quantification of chondroitin sulfation for treatment monitoring. Our data demonstrate that bone-remodeling cell types are accessible to systemically delivered rhARSB, whereas the uptake into chondrocytes is inefficient.

Identification of a critical sulfation in chondroitin that inhibits axonal regeneration.

The failure of mammalian CNS neurons to regenerate their axons derives from a combination of intrinsic deficits and extrinsic factors. Following injury, chondroitin sulfate proteoglycans (CSPGs) within the glial scar inhibit axonal regeneration, an action mediated by the sulfated glycosaminoglycan (GAG) chains of CSPGs, especially those with 4-sulfated (4S) sugars. Arylsulfatase B (ARSB) selectively cleaves 4S groups from the non-reducing ends of GAG chains without disrupting other, growth-permissive motifs. We demonstrate that ARSB is effective in reducing the inhibitory actions of CSPGs both in in vitro models of the glial scar and after optic nerve crush (ONC) in adult mice. ARSB is clinically approved for replacement therapy in patients with mucopolysaccharidosis VI and therefore represents an attractive candidate for translation to the human CNS.

The effect of galsulfase enzyme replacement therapy on the growth of patients with mucopolysaccharidosis VI (Maroteaux-Lamy syndrome).

Mucopolysaccharidosis (MPS) VI is an autosomal recessive lysosomal storage disorder arising from deficient activity of N-acetylgalactosamine-4-sulfatase (arylsulfatase B) and subsequent intracellular accumulation of the glycosaminoglycans (GAGs) dermatan sulfate and chondroitin-4-sulfate. Manifestations are multi-systemic and include skeletal abnormalities such as dysostosis multiplex and short stature. Reference height-for-age growth charts for treatment-naïve MPS VI patients have been published for both the slowly and rapidly progressing populations. Categorization of disease progression for these charts was based on urinary GAG (uGAG) level; high (>200µg/mg creatinine) levels identified subjects as rapidly progressing. Height data for 141 patients who began galsulfase treatment by the age of 18years were collected and stratified by baseline uGAG level and age at ERT initiation in 3-year increments. The reference MPS VI growth charts were used to calculate change in Z-score from pre-treatment baseline to last follow-up. Among patients with high baseline uGAG levels, galsulfase ERT was associated with an increase in Z-score for those beginning treatment at 0-3, >3-6, >6-9, >9-12, and >12-15years of age (p<0.05). Increases in Z-score were not detected for patients who began treatment between 15 and 18years of age, nor for patients with low (≤200µg/mg creatinine) baseline uGAG levels, regardless of age at treatment initiation. The largest positive deviation from untreated reference populations was seen in the high uGAG excretion groups who began treatment by 6years of age, suggesting an age- and severity-dependent impact of galsulfase ERT on growth.

IgE-Mediated Hypersensitivity and Desensitisation with Recombinant Enzymes in Pompe Disease and Type I and Type VI Mucopolysaccharidosis.

Enzyme replacement therapy (ERT) is important for the treatment of lysosomal storage disorders. Hypersensitivity reactions with ERT have been reported, and in these cases, desensitisation with the enzyme is necessary. Here we report the cases of 3 patients with lysosomal storage disorders, including Pompe disease and mucopolysaccharidosis type I and VI, who had IgE-mediated hypersensitivity reactions and positive skin tests. Successful desensitisation protocols with the culprit enzyme solution were used for these patients. All 3 patients were able to safely receive ERT with the desensitisation protocol.

Eficacia y seguridad de galsulfasa en pacientes con diagnóstico de mucopolisacaridosis tipo VI / Efficacy and safety of galsulfase in patients with a diagnosis of mucopolysaccharidosis type VI

INTRODUCCION: Antecedentes: El Instituto de Evaluación de Tecnologías en Salud e Investigación (IETSI) ha recibido la solicitud de evaluar el uso de Galsulfasa para el uso en pacientes con diagnóstico de mucopolisacaridosis tipo VI (MPS-VI) confirmada por pruebas enzimáticas o genéticas y que presentan síntomas y signos propios de la enfermedad, indicación actualmente no contemplada en el Petitorio Farmacológico de ESSALUD. Aspectos Generales: La mucopolisacaridosis de tipo VI (MPS-VI) o síndrome de Maroteaux-Lamy es una enfermedad de almacenamiento lisosómico con afectación sistémica progresiva, asociada a un déficit de la enzima N-acetilgalactosamina 4-sulfatasa, conocida también como arilsulfatasa B (ASB). Este déficit enzimático provoca la acumulación de dermatán sulfato. Esta enfermedad presenta un amplio espectro de signos y síntomas. Se caracteriza por presentar displasia esquelética que incluye: estatura baja, disostosis múltiple y enfermedad articular degenerativa. La MPS-VI es una enfermedad de transmisión autosómica recesiva, causada por mutaciones en el gen ARSB, ubicado en el cromosoma 5. Se estima que aproximadamente 1 en 340,000 nacimientos están afectados con MPS-VI. Tecnología Sanitaria de Interés: Galsulfasa: La galsulfasa (Naglazyme O) es una forma recombinante de la enzima N-acetilgalactosamina-4-sulfatasa humana. Es el único tratamiento de reemplazo enzimático propuesto disponible para la MPS-VI. El fundamento y mecanismo de acción del tratamiento enzimático sustitutivo es restablecer un nivel de actividad enzimática suficiente para hidrolizar el sustrato y evitar la acumulación de dermatán sulfato. Tras la perfusión intravenosa, la galsulfasa se elimina rápidamente de la circulación y es captada por las células, probablemente por los receptores manosa-6-fosfato, y transportada a los lisosomas.\r\nMETODOLOGÍA: Se realizó una búsqueda de la literatura con respecto a la eficacia y seguridad de \r\nGalsulfasa para el tratamiento de MPS-VI en las bases de datos de MEDLINE, EMBASE, CENTRAL, DARE y TRIPDATABASE. Se hizo una búsqueda adicional en www.clinicaltrials.gov, para poder identificar ensayos clínicos aún en elaboración o que no hayan sido publicados. RESULTADOS: Sinopsis de la Evidencia: Se realizó la búsqueda bibliográfica y de evidencia científica que sustente el uso de galsulfasa en el tratamiento de MPS-VI. Guías Clínicas: se identificaron cuatro documentos de guías de tratamiento; Evaluaciones de tecnología sanitaria: se identificó una ETS (España). Galsulfasa no ha sido evaluado hasta el momento por las agencias de ETS de NICE o IETS, tampoco por ningunas de las agencias miembros de la INAHTA; Revisiones sistemáticas: Se identificó una RS Cochrane; Ensayos clínicos: se identificaron cuatro ensayos de los cuales solo uno es un ECA fase III controlado con placebo, el resto corresponden a ensayos de un solo brazo sin grupo comparador (un ensayo fase 1/11, uno de fase II, uno de fase IV); Ensayos Clínicos registrados: se encontró un estudio registrado en fase de reclutamiento; Estudios observacionales: se identificó un estudio transversal con mediciones en dos puntos temporales. CONCLUSIONES: La presente evaluación identificó cinco ensayos que evaluaron galsulfasa en la MPS VI y un reciente estudio transversal. El estudio de Harmatz 2006 es el único ensayo que provee información sobre la eficacia de galsulfasa por ser aleatorizado y controlado con placebo. El resto de ensayos fueron de fase I o II de un solo brazo o comparando dos dosis diferentes, y en muestras pequeñas (5 10 pacientes). El estudio transversal comparó parámetros clínicos y de laboratorio de pacientes con MPS VI obtenidos en dos encuestas realizadas con diez años de diferencia, pero en la segunda medición solo se recogió información de aproximadamente la mitad de los pacientes. El Instituto de Evaluación de Tecnología en Salud e Investigación-IETSI, no aprueba el uso de galsulfasa para el tratamiento de la mucopolisacaridosis tipo VI.

Pharmacodynamics, pharmacokinetics and biodistribution of recombinant human N-acetylgalactosamine 4-sulfatase after 6months of therapy in cats using different IV infusion durations.

BACKGROUND: Mucopolysaccharidosis VI (MPS VI) is a lysosomal storage disease characterized by an absence or marked reduction of lysosomal N-acetylgalactosamine-4-sulfatase activity. Affected individuals have widespread accumulation of unmetabolized glycosaminoglycan substrates leading to detrimental effects. Recombinant human N-acetylgalactosamine 4-sulfatase (rhASB) is an approved enzyme replacement therapy for patients with MPS VI. Despite the known efficacy of weekly 4-h rhASB infusions, some clinicians wish to treat patients using reduced infusion times. This study compared the pharmacodynamics, pharmacokinetics, and tissue biodistribution of rhASB when administered as 2- and 4-h intravenous infusions using a feline model of MPS VI. METHODS: Study animals were MPS VI-affected cats that demonstrate clinical signs and biochemical derangements similar to human MPS VI patients. Beginning at age 4weeks, animals received weekly 2-h (N=6) or 4-h (N=6) IV infusions of rhASB for 26weeks (Naglazyme® [galsulfase] Solution for Intravenous Infusion; BioMarin Pharmaceutical, Inc.). The control group consisted of untreated MPS VI-affected cats (N=6). The pharmacokinetic parameters of plasma rhASB and urinary glycosaminoglycan were determined at weeks 13 and 26. Animals were euthanized 48h after the last infusion and tissue concentration of ASB, GAG and ß-glucuronidase were measured in the liver, spleen, aorta, and kidney. Skeletal and ophthalmological evaluations were performed within 2weeks of euthanasia. RESULTS: At week 13, the mean AUC0-t in animals treated with 4-h infusions was similar to 2-h infusions while the Cmax of the 4-h infusion was 50% of the 2-h infusion. By week 26, the mean AUC0-t of the 4-h infusion was 1.3-fold higher than the 2-h infusion (p<0.05) while Cmax of the 4-h infusion was 70% of the 2-h infusion (p<0.05). Among animals treated with 2- and 4-h infusions, there was no difference in urinary GAG excretion, tissue GAG storage, tissue galsulfase activity, and ß-glucuronidase but all were significantly different than control animals (for each, p<0.001). Radiographic skeletal abnormality scores for animals were also similar for both treatment groups and significantly higher than control animals (p<0.001). There was no significant difference in corneal clouding scores among treated and untreated animals. CONCLUSIONS: There was no significant difference in clinical outcomes when rhASB was administered to MPS VI affected cats as 2- and 4-h infusions over 26weeks. Additional studies may determine if shorter infusion times are appropriate for MPS VI patients without significant infusion-associated reactions.

Galsulfase (Naglazyme®) therapy in infants with mucopolysaccharidosis VI.

OBJECTIVE: To evaluate the efficacy and safety of two dose levels of galsulfase (Naglazyme®) in infants with MPS VI. STUDY DESIGN: This was a phase 4, multicenter, multinational, open-label, two-dose level study. Subjects were randomized 1:1 to receive weekly infusions of 1.0 or 2.0 mg/kg of galsulfase for a minimum of 52 weeks. Progression of skeletal dysplasia was determined by monitoring physical appearance, radiographic changes, and growth. Urinary glycosaminoglycan (GAG) levels, gross and fine motor function, cardiac function, vision, hearing, and health resource utilization were evaluated. Safety assessments were performed. RESULTS: Four infants (aged 3.3-12.7 months) participated in the study. Galsulfase was well tolerated at 1.0 and 2.0 mg/kg/week dose levels with no drug-related serious adverse events. Two subjects experienced a total of four possible treatment-related adverse events which were all considered mild. Length and weight remained within age-expected norms. Skeletal abnormalities continued to progress in all subjects. High baseline urinary GAG levels (mean: 870 µg/mg creatinine) decreased by approximately 70%; these reduced levels were maintained (mean: 220 µg/mg creatinine at week 52) despite the development of anti-galsulfase antibodies. Hearing, cardiac function, hepatosplenomegaly, and facial dysmorphism stabilized or improved, but corneal clouding progressed. There was no clear difference in safety or efficacy between the two doses. CONCLUSIONS: Galsulfase at two dose levels was safe and well tolerated in infants. Normal growth was maintained but skeletal abnormalities continued to progress. Urinary GAG levels decreased with treatment. Early initiation of galsulfase may prevent or slow progression of some disease manifestations.

Informe de evaluación rápida de tecnología sobre seguridad y efectividad de la galsulfasa para mucopolisacaridosis tipo VI / Rapid evaluation report of technology on safety and effectiveness of galsulfase for mucopolysaccharidosis type VI

La mucopolisacaridosis tipo VI (MPS VI), o también llamada síndrome de Maroteaux- Lamy, es una enfermedad por depósito lisosómico (MDL). Está causada por el déficit de la enzima de N-acetilgalactosamina-4-sulfatosulfatasa o arisulfatasa B (ARSB) necesario para la degradación del dermatán sulfato, un tipo de glicosaminoglicano (GAG) y principal componente principal del tejido conectivo. La progresiva acumulación de dermatán sulfato en los lisosomas puede conducir a daños tisulares irreversibles y alterar la función normal de algunos órganos. Como resultado de la utilización de galsulfasa en pacientes con mucopolisacaridosis tipo VI se observó mejoras en su estado funcional y en términos de calidad de vida. Se recomienda cubrir con generación de evidencia.(AU)

Ethical and economic considerations of rare diseases in ethnic minorities: the case of mucopolysaccharidosis VI in Colombia.

Mucopolysaccharidosis VI is an autosomal recessive lysosomal storage disorder associated with severe disability and premature death. The presence of a mucopolysaccharidosis-like disease in indigenous ethnic groups in Colombia can be inferred from archaeological findings. There are several indigenous patients with mucopolysaccharidosis VI currently receiving enzyme replacement therapy. We discuss the ethical and economic considerations, regarding both direct and indirect costs, of a high-cost orphan disease in a marginalised minority population in a developing country.

Intrathecal recombinant human 4-sulfatase reduces accumulation of glycosaminoglycans in dura of mucopolysaccharidosis VI cats.

INTRODUCTION: Mucopolysaccharidosis VI (MPS-VI) is caused by a deficiency in N-acetylgalactosamine-4-sulfatase activity, resulting in lysosomal accumulation of partially degraded glycosaminoglycans (GAGs). Compressive myelopathy in early-onset MPS-VI patients has been partly attributed to thickening of the dura mater following engorgement with GAG. In this study, we therefore tested whether the dural abnormalities could be prevented in a feline model of the disorder. RESULTS: All intrathecal injections (IT-INJs) were well tolerated. MPS-VI cats treated with IT-INJ of recombinant human N-acetylgalactosamine-4-sulfatase (rhASB) exhibited reduced vacuolation in the dural fibroblasts, diminished levels of sulfated-N-acetylhexosamine (HNAc(+S)) in the cerebrospinal fluid (CSF) and no hind-limb paresis. Serum anti-rhASB antibodies remained low in MPS-VI cats treated with intravenous enzyme replacement therapy (IV-ERT) and increased slightly in normal cats treated with IT-INJ of rhASB alone. Anti-rhASB antibodies in CSF remained undetectable. DISCUSSION: These data indicate that repeated IT-INJ of rhASB can safely prevent GAG storage in MPS-VI dura. METHODS: Cats were assigned to three groups: (i) receiving weekly IV-ERT of rhASB from birth plus six monthly IT-INJs of rhASB from age 2 months; (ii) receiving six monthly IT-INJs of vehicle; or (iii) untreated. Additional normal cats received five fortnightly IT-INJs of rhASB or vehicle alone.

Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI): a single dose of galsulfase further reduces urine glycosaminoglycans after hematopoietic stem cell transplantation.

BACKGROUND: Maroteaux-Lamy syndrome, or mucopolysaccharidosis (MPS) type VI, is the autosomal recessive lysosomal disorder resulting from deficient N-acetylgalactosamine 4-sulfatase (ARSB) and the consequent accumulation of glycosaminoglycan (GAG). Patients fully engrafted after hematopoietic stem cell transplantation (HSCT) demonstrate several indicators of metabolic correction such as reduction in liver size, absence of hepatic ultrastructural pathology, and patients do not develop cervical cord compression. Engrafted patients demonstrate reduction in urine GAG achieving near-normal levels. HYPOTHESIS: We presumed that HSCT engraftment from a normal individual would provide sufficient systemic enzyme to accomplish maximal metabolic correction, and that no additional benefit would accrue from additional therapy such as with intravenous recombinant human ARSB protein, galsulfase. MATERIALS AND METHODS: A 22-year-old male had received an allogeneic bone marrow transplant from an HLA-identical sibling donor, and remained fully engrafted after 20 years. In response to his request regarding the potential benefit of enzyme replacement therapy, we administered a single, standard dose of galsulfase while monitoring urine GAG daily, before and after the treatment. RESULTS: Urine GAG declined from slightly high pre-treatment levels (7.63 mg GAG/mmol creatinine; range 7.0-8.5, N=3) progressively declining below the age-specific normal range (<6.5) over 10 days to the lowest level of 4.4, with a mean post-treatment level of 5.60 (N=10). CONCLUSIONS: Somewhat surprisingly, the biomarker urine GAG was significantly reduced after a single treatment of intravenous galsulfase thus suggesting that supplemental enzyme replacement therapy might improve the clinical outcome for donor-engrafted patients with MPS VI.

Intrathecal administration of recombinant human N-acetylgalactosamine 4-sulfatase to a MPS VI patient with pachymeningitis cervicalis.

In mucopolysaccharidosis VI, or Maroteaux-Lamy syndrome, deficiency of N-acetylgalactosamine 4-sulfatase leads to storage of glycosaminoglycans (GAGs) and MPS VI patients often develop spinal cord compression during the course of the disease due to GAG storage within the cervical meninges, requiring neurosurgical intervention, as intravenous (IV) enzyme replacement therapy (ERT) is not expected to cross the blood-brain barrier. We report the use of intrathecal (IT) recombinant human N-acetylgalactosamine 4-sulfatase (arylsulfatase B, or ASB) in a MPS VI child with spinal cord compression whose parents initially refused the surgical treatment. Assessments were performed at baseline, with clinical, neurological and biochemical evaluations, urodynamic studies and MRI of the CNS. Changes on these parameters were evaluated after IT infusions of ASB administered monthly via lumbar puncture (LP) in a IV ERT naive patient. To our knowledge, this was the first MPS VI patient who received IT ERT. Despite significant urodynamic improvement and some neurological amelioration, the patient developed worsening of walking capacity. After IV ERT was started, the patient presented with a generalized hypotonia and a life-saving surgical fixation of the neck was then performed. The results observed on this MPS VI patient suggest that instability of the cervical vertebrae could be unmasked by IV ERT as joint storage is reduced, and the decrease in neck stiffness and stability could confound the expected improvement of SCC manifestations following IT ERT. The study of further patients, if possible in a clinical trial setting, is needed to evaluate the potential of a non-surgical IT ERT treatment of SCC for MPS VI.

Enzyme replacement therapy in the home setting for mucopolysaccharidosis VI: a survey of patient characteristics and physicians' early findings in the United States.

Galsulfase, a Food and Drug Administration-approved enzyme replacement therapy for mucopolysaccharidosis VI, is administered once weekly in a hospital setting as a 4-hour intravenous infusion. To improve convenience and alleviate family responsibilities associated with clinic visits, some physicians are transitioning appropriate patients to home infusion therapy. An online survey was conducted with 3 physicians treating 4 patients with mucopolysaccharidosis VI to better understand the factors motivating the transition to home infusion therapy, identify characteristics of appropriate candidates, and evaluate the potential impact on the lives of patients and their families. Survey results showed that home infusion may offer patients and their families increased flexibility of schedule and enhanced family life.

Does enzyme replacement therapy influence the ocular changes in type VI mucopolysaccharidosis?

BACKGROUND: To describe the ocular changes noted in seven patients with type VI mucopolysaccharidosis (MPS VI) during 44 months of follow-up while on enzyme replacement therapy (ERT). METHODS: One male and six female patients with MPS VI were followed-up for a mean period of 44 months while undergoing enzyme replacement therapy (ERT) with recombinant arylsulfatase B (Naglazyme). They were examined annually for visual acuity, corneal clouding, intraocular pressure (IOP), optic nerve head and fundus morphology. Corneal clouding was documented by photography. We acknowledge that our methodology may not have been sensitive enough to detect extremely mild ocular changes, including minimal increases in corneal thickness or clouding. Nevertheless, this limitation has been considered in the interpretation of our findings. RESULTS: Ophthalmological findings remained stable in 5/7 patients. One patient experienced a modest improvement in visual acuity of more than 2 Snellen lines in one eye, while another patient suffered a deterioration in visual acuity of more than 2 Snellen lines in both eyes. Five out of seven patients showed optic nerve pathology: two of these exhibited optic nerve head swelling, while the other three showed variable degrees of optic nerve atrophy. All seven patients suffered from the typical corneal stromal opacities, however, to variable extents. CONCLUSION: Visual function and ocular findings did not deteriorate in six out of seven MPS VI patients during a mean follow-up period of 3 and a half years on ERT.

Home treatment with Elaprase and Naglazyme is safe in patients with mucopolysaccharidoses types II and VI, respectively.

Enzyme replacement therapy for lysosomal storage disorders has made an important contribution to improving the quality of life of affected patients. The treatment, however, is invasive and onerous, involving weekly or biweekly intravenous infusions of product over a 3-4 h period. Such therapy can be extremely disruptive of normal family life and the provision of a safe, home treatment regimen is greatly appreciated by affected families. In this report we demonstrate the safety of home treatment with Elaprase for mucopolysaccharidosis type II (17 patients) and Naglazyme for mucopolysaccharidosis type VI (6 patients). Careful patient selection, an experienced home care company and a detailed management plan for potential anaphylaxis and infusion-associated reactions are important components in a successful home treatment programme.

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.

Biochemical, pathological, and skeletal improvement of mucopolysaccharidosis VI after gene transfer to liver but not to muscle.

Mucopolysaccharidosis VI (MPS VI) is caused by deficient activity of arylsulfatase B (ARSB), resulting in intralysosomal storage of dermatan sulfate (DS) and multisystem disease without central nervous system involvement. After gene transfer, muscle or liver can theoretically be converted into factories for systemic ARSB secretion, leading to uptake by non-transduced cells. We have injected newborn MPS VI rats and cats with adeno-associated viral (AAV) vectors expressing ARSB under the control of liver-specific, muscle-specific, or universally active promoters. After systemic or intramuscular (IM) administration of AAV, therapeutic levels of circulating ARSB are achieved, resulting in skeletal improvements and significant decrease in glycosaminoglycan (GAG) storage, inflammation and apoptosis (despite a neutralizing immune response to ARSB in MPS VI rats). In addition, we have observed wide-spread dissemination of vector after IM AAV administration. This results in secretion of therapeutic levels of ARSB when the universally active cytomegalovirus (CMV) but not the muscle-specific muscle creatine kinase (MCK) promoter is used, suggesting that transduction of extramuscular sites rather than enzyme secretion from muscle occurs after muscle ARSB gene transfer. We conclude that AAV-mediated expression of ARSB from liver represents a feasible therapeutic strategy for MPS VI, potentially avoiding multiple infusions of costly recombinant enzyme associated with enzyme replacement therapy.

Long-term intra-articular administration of recombinant human N-acetylgalactosamine-4-sulfatase in feline mucopolysaccharidosis VI.

Degenerative joint disease (DJD) is one aspect of mucopolysaccharidosis VI (MPS VI) pathology that has proven resistant to systemic enzyme replacement therapy (ERT). In this study the effect of repeated intra-articular injections (IA INJ) of recombinant human acetylgalactosamine-4-sulfatase (rh4S) on DJD was examined. Four MPS VI cats received i.v. ERT weekly from birth plus IA INJ (0 or 500 microg of rh4S per joint; monthly or every three months) while three MPS VI cats received IA INJ only. After 10 months, shoulders, elbows and knees were compared. Taken individually, an improvement in joint appearance was observed between the joints that received rh4S monthly or every three months compared with the contralateral joints treated with buffer or at lower frequency. Within articular cartilage of joints treated more frequently, the depth of clearance of lysosomal storage tended to be greater and uronic acid content was reduced reflecting the removal of glycosaminoglycans. Synovium in treated joints also showed less storage. No abnormal clinical signs were observed after the IA INJ and negligible antibody titres were measured throughout the study. No clear benefit was observed by combining IA INJ with weekly ERT and the most significant improvement in joint appearance resulted from increased IA INJ frequency. These data support the view that intra-articular therapy may be a good option for preventing the development of the severe articular pathology in MPS VI.

Intra-articular enzyme administration for joint disease in feline mucopolysaccharidosis VI: enzyme dose and interval.

Degenerative joint changes have been reported in human mucopolysaccharidosis VI (MPS VI) and are a prominent feature of feline MPS VI. Joint disease has proven refractory to intravenous enzyme replacement therapy (ERT) in the MPS VI cat because enzyme is unable to reach cells in cartilage. In this study, enzyme was infused directly into the intraarticular space to determine whether joint tissues are able to respond to replacement enzyme. Clearance of glycosaminoglycans from chondrocytes was observed at a dose of 10 microg recombinant human N-acetylgalactosamine-4-sulfatase (rh4S), but greater clearance was observed with higher doses. The chondrocytes at the articular surface were cleared preferentially. Lysosomal vacuolation in cruciate ligament and synovial cells also decreased upon addition of rh4S. One month after injection of rh4S, a slight reaccumulation of storage was observed at the surface of the joint, but extensive reaccumulation was observed 2 mo after injection. These results indicate that by bypassing the synovium using intraarticular ERT, significant reduction in storage material in joint tissues can be achieved. Localized ERT in the joint space provides a mechanism for delivering enzyme directly to the articular cartilage and a potential therapy for joint pathology in MPS VI.

Galsulfase: arylsulfatase B, BM 102, recombinant human arylsulfatase B, recombinant human N-acetylgalactosamine-4-sulfatase, rhASB.

Galsulfase [Aryplase, arylsulfatase B, BM 102, Naglazyme, rhASB, recombinant human N-acetylgalactosamine-4-sulfatase, recombinant human arylsulfatase B] is under development with BioMarin Pharmaceutical as an enzyme replacement therapy for the treatment of mucopolysaccharidosis (MPS) VI. MPS VI (also known as Maroteaux-Lamy syndrome) is a progressive, debilitating genetic disease resulting in early death. Patients with MPS VI have a deficiency in the arylsulfatase B (ASB) enzyme that is essential for the progressive breakdown of certain complex carbohydrates. The deficiency in ASB results in the build-up of carbohydrate residues in the lysosomes in all cells of the body. Patients are usually diagnosed at 6-24 months of age, and the symptoms include deceleration of growth, enlarged liver and spleen, skeletal and joint deformities, and upper airway obstruction. Patients do not survive past 20-30 years of age in the more severe cases, but may live longer with the milder cases, but with significant medical problems. While the symptoms of MPS VI are similar to those of MPS I, mental retardation associated with the severe forms of MPS I had not been reported for patients with MPS VI. For some patients, bone marrow transplantation is a treatment, albeit risky, option. MPS VI afflicts approximately 1100 patients in the world. In November 2004, BioMarin announced that it has filed a Biologics License Application (BLA) with the the US FDA for galsulfase for the treatment of MPS VI. The company has requested a priority review as part of the BLA submission, which, if granted, is expected to be completed within 6 months of submission. The FDA accepted the filing of the BLA for galsulfase for MPS VI in February 2005, and granted it a 6-month priority review period. The FDA's decision is due on 31 May 2005. The FDA has granted galsulfase orphan drug status and fast-track designation. Orphan drug status will provide BioMarin Pharmaceutical with 7 years of marketing exclusivity for galsulfase in the US providing that galsulfase is the first agent to gain approval in the US for MPS VI. BioMarin received an orphan drug designation from the EC for galsulfase for the treatment of MPS VI. Following positive safety and efficacy results from the phase I study with galsulfase, BioMarin Pharmaceutical commenced and successfully completed a phase II trial with rhASB in ten patients with MPS VI. This 24-week, open-label, multicentre trial was conducted at two sites, in the US and Australia (at the Lysosomal Diseases Research Unit, Women's and Children's Hospital, Adelaide, Australia, by Dr John Hopwood), and evaluated the safety, efficacy and pharmacokinetics of weekly intravenous infusions of galsulfase at a dose of 1.0 mg/kg. BioMarin Pharmaceutical completed a phase I/II clinical trial of galsulfase in six patients with MPS VI in the Children's Hospital, Oakland, CA, USA, with Dr Paul Harmatz as a principal investigator. This randomised, double-blind study evaluated the safety and efficacy of two doses of galsulfase administered by weekly intravenous infusions for 24 weeks. Five patients from the phase I study had completed the 24-week, open-label extension study. Data from this study confirmed safety and good tolerability of both doses of galsulfase with the 1.0 mg/kg dose producing greater sustained effects. The patients will continue receiving therapy in the future. Seven preclinical trials with galsulfase were conducted in a naturally occurring feline model of MPS VI disease at the Lysosomal Diseases Research Unit, Women's and Children's Hospital, Adelaide, Australia, by Dr John Hopwood. The company manufactures galsulfase at a GMP facility licensed from the State of California.