Enzyme replacement therapy for Mucopolysaccharidosis Type I among patients followed within the MPS Brazil Network

Preclinical Enzyme Replacement Therapy with a Recombinant β-Galactosidase-Lectin Fusion for CNS Delivery and Treatment of GM1-Gangliosidosis

GM1-gangliosidosis is a catastrophic, neurodegenerative lysosomal storage disease caused by a deficiency of lysosomal β-galactosidase (β-Gal). The primary substrate of the enzyme is GM1-ganglioside (GM1), a sialylated glycosphingolipid abundant in nervous tissue. Patients with GM1-gangliosidosis present with massive and progressive accumulation of GM1 in the central nervous system (CNS), which leads to mental and motor decline, progressive neurodegeneration, and early death. No therapy is currently available for this lysosomal storage disease. Here, we describe a proof-of-concept preclinical study toward the development of enzyme replacement therapy (ERT) for GM1-gangliosidosis using a recombinant murine β-Gal fused to the plant lectin subunit B of ricin (mβ-Gal:RTB). We show that long-term, bi-weekly systemic injection of mβ-Gal:RTB in the β-Gal-/- mouse model resulted in widespread internalization of the enzyme by cells of visceral organs, with consequent restoration of enzyme activity. Most importantly, β-Gal activity was detected in several brain regions. This was accompanied by a reduction of accumulated GM1, reversal of neuroinflammation, and decrease in the apoptotic marker caspase 3. These results indicate that the RTB lectin delivery module enhances both the CNS-biodistribution pattern and the therapeutic efficacy of the β-Gal ERT, with the potential to translate to a clinical setting for the treatment of GM1-gangliosidosis.

Non-cardiac Manifestations in Adult Patients With Mucopolysaccharidosis

Mucopolysaccharidoses (MPS) are a heterogeneous group of disorders that results in the absence or deficiency of lysosomal enzymes, leading to an inappropriate storage of glycosaminoglycans (GAGs) in various tissues of the body such as bones, cartilage, heart valves, arteries, upper airways, cornea, teeth, liver and nervous system. Clinical manifestations can become progressively exacerbated with age and affect their quality of life. Developments in advanced supportive treatment options such as enzyme replacement therapy (ERT), hematopoietic stem cell transplantation (HSCT) may have improved patients' life span. Adult MPS patients require specialist clinical surveillance long-term. In many cases, in addition to the MPS-related health problems, they may develop age-related complications. Considering the complexity of their clinical manifestations and lack of guidelines on the management of adult MPS disorders, multispecialty and multidisciplinary teams' care is essential to diagnose and treat health problems that are likely to be encountered. This review presents non-cardiac clinical manifestations, their pathophysiology, management and long-term outcomes in adult MPS patients.

The natural history of neurocognition in MPS disorders: A review

MPS disorders are associated with a wide spectrum of neurocognitive effects, from mild problems with attention and executive functions to progressive and degenerative neuronopathic disease. Studies of the natural history of neurocognition are necessary to determine the profile of abnormality and the rates of change, which are crucial to select endpoints for clinical trials of brain treatments and to make clinical recommendations for interventions to improve patients' quality of life. The goal of this paper is to review neurocognitive natural history studies to determine the current state of knowledge and assist in directing future research in all MPS disorders. There are seven different types of MPS diseases, each resulting from a specific enzyme deficiency and each having a separate natural history. MPS IX, will not be discussed as there are only 4 cases reported in the literature without cognitive abnormality. For MPS IH, hematopoietic cell transplant (HCT) is standard of care and many studies have documented the relationship between age at treatment and neurocognitive outcome, and to a lesser extent, neurocognitive status at baseline. However, the mortality and morbidity associated with the transplant process and residual long-term problems after transplant, have led to renewed efforts to find better treatments. Rather than natural history, new trials will likely need to use the developmental trajectories of the patients with HCT as a comparators. The literature has extensive data regarding developmental trajectories post-HCT. For attenuated MPS I, significant neurocognitive deficits have been documented, but more longitudinal data are needed in order to support a treatment directed at their attention and executive function abnormalities. The neuronopathic form of MPS II has been a challenge due to the variability of the trajectory of the disease with differences in timing of slowing of development and decline. Finding predictors of the course of the disease has only been partially successful, using mutation type and family history. Because of lack of systematic data and clinical trials that precede a thorough understanding of the disease, there is need for a major effort to gather natural history data on the entire spectrum of MPS II. Even in the attenuated disease, attention and executive function abnormalities need documentation. Lengthy detailed longitudinal studies are needed to encompass the wide variability in MPS II. In MPS IIIA, the existence of three good natural history studies allowed a quasi-meta-analysis. In patients with a rapid form of the disease, neurocognitive development slowed up until 42 to 47 months, halted up to about 54 months, then declined rapidly thereafter, with a leveling off at an extremely low age equivalent score below 22 months starting at about chronological age of 6. Those with slower or attenuated forms have been more variable and difficult to characterize. Because of the plethora of studies in IIIA, it has been recommended that data be combined from natural history studies to minimize the burden on parents and patients. Sufficient data exists to understand the natural history of cognition in MPS IIIA. MPS IIIB is quite similar to IIIA, but more attenuated patients in that phenotype have been reported. MPS IIIC and D, because they are so rare, have little documentation of natural history despite the prospects of treatments. MPS IV and VI are the least well documented of the MPS disorders with respect to their neurocognitive natural history. Because, like attenuated MPS I and II, they do not show progression of neurocognitive abnormality and most patients function in the range of normality, their behavioral, attentional, and executive function abnormalities have been ignored to the detriment of their quality of life. A peripheral treatment for MPS VII, extremely rare even among MPS types, has recently been approved with a post-approval monitoring system to provide neurocognitive natural history data in the future. More natural history studies in the MPS forms with milder cognitive deficits (MPS I, II, IV, and VI) are recommended with the goal of improving these patients' quality of life with and without new brain treatments, beyond the benefits of available peripheral enzyme replacement therapy. Recommendations are offered at-a-glance with respect to what areas most urgently need attention to clarify neurocognitive function in all MPS types.

Mucopolysaccharidosis Type I: Current Treatments, Limitations, and Prospects for Improvement

Mucopolysaccharidosis type I (MPS I) is a lysosomal disease, caused by a deficiency of the enzyme alpha-L-iduronidase (IDUA). IDUA catalyzes the degradation of the glycosaminoglycans dermatan and heparan sulfate (DS and HS, respectively). Lack of the enzyme leads to pathologic accumulation of undegraded HS and DS with subsequent disease manifestations in multiple organs. The disease can be divided into severe (Hurler syndrome) and attenuated (Hurler-Scheie, Scheie) forms. Currently approved treatments consist of enzyme replacement therapy (ERT) and/or hematopoietic stem cell transplantation (HSCT). Patients with attenuated disease are often treated with ERT alone, while the recommended therapy for patients with Hurler syndrome consists of HSCT. While these treatments significantly improve disease manifestations and prolong life, a considerable burden of disease remains. Notably, treatment can partially prevent, but not significantly improve, clinical manifestations, necessitating early diagnosis of disease and commencement of treatment. This review discusses these standard therapies and their impact on common disease manifestations in patients with MPS I. Where relevant, results of animal models of MPS I will be included. Finally, we highlight alternative and emerging treatments for the most common disease manifestations.

Intravenous Enzyme Replacement Therapy in Mucopolysaccharidoses: Clinical Effectiveness and Limitations

The aim of this review is to summarize the evidence on efficacy, effectiveness and safety of intravenous enzyme replacement therapy (ERT) available for mucopolysaccharidoses (MPSs) I, II, IVA, VI and VII, gained in phase III clinical trials and in observational post-approval studies. Post-marketing data are sometimes conflicting or controversial, possibly depending on disease severity, differently involved organs, age at starting treatment, and development of anti-drug antibodies (ADAs). There is general agreement that ERT is effective in reducing urinary glycosaminoglycans and liver and spleen volume, while heart and joints outcomes are variable in different studies. Effectiveness on cardiac valves, trachea and bronchi, hearing and eyes is definitely poor, probably due to limited penetration in the specific tissues. ERT does not cross the blood–brain barrier, with the consequence that the central nervous system is not cured by intravenously injected ERT. All patients develop ADAs but their role in ERT tolerance and effectiveness has not been well defined yet. Lack of reliable biomarkers contributes to the uncertainties about effectiveness. The data obtained from affected siblings strongly indicates the need of neonatal screening for treatable MPSs. Currently, other treatments are under evaluation and will surely help improve the prognosis of MPS patients.

Mucopolysaccharidosis Type I

Mucopolysaccharidosis type I (MPS I) is caused by the deficiency of α-l-iduronidase, leading to the storage of dermatan and heparan sulfate. There is a broad phenotypical spectrum with the presence or absence of neurological impairment. The classical form is known as Hurler syndrome, the intermediate form as Hurler-Scheie, and the most attenuated form is known as Scheie syndrome. Phenotype seems to be largely influenced by genotype. Patients usually develop several somatic symptoms such as abdominal hernias, extensive dermal melanocytosis, thoracolumbar kyphosis odontoid dysplasia, arthropathy, coxa valga and genu valgum, coarse facial features, respiratory and cardiac impairment. The diagnosis is based on the quantification of α-l-iduronidase coupled with glycosaminoglycan analysis and gene sequencing. Guidelines for treatment recommend hematopoietic stem cell transplantation for young Hurler patients (usually at less than 30 months of age). Intravenous enzyme replacement is approved and is the standard of care for attenuated-Hurler-Scheie and Scheie-forms (without cognitive impairment) and for the late-diagnosed severe-Hurler-cases. Intrathecal enzyme replacement therapy is under evaluation, but it seems to be safe and effective. Other therapeutic approaches such as gene therapy, gene editing, stop codon read through, and therapy with small molecules are under development. Newborn screening is now allowing the early identification of MPS I patients, who can then be treated within their first days of life, potentially leading to a dramatic change in the disease's progression. Supportive care is very important to improve quality of life and might include several surgeries throughout the life course.

Canine Models of Inherited Musculoskeletal and Neurodegenerative Diseases

Mouse models of human disease remain the bread and butter of modern biology and therapeutic discovery. Nonetheless, more often than not mouse models do not reproduce the pathophysiology of the human conditions they are designed to mimic. Naturally occurring large animal models have predominantly been found in companion animals or livestock because of their emotional or economic value to modern society and, unlike mice, often recapitulate the human disease state. In particular, numerous models have been discovered in dogs and have a fundamental role in bridging proof of concept studies in mice to human clinical trials. The present article is a review that highlights current canine models of human diseases, including Alzheimer's disease, degenerative myelopathy, neuronal ceroid lipofuscinosis, globoid cell leukodystrophy, Duchenne muscular dystrophy, mucopolysaccharidosis, and fucosidosis. The goal of the review is to discuss canine and human neurodegenerative pathophysiologic similarities, introduce the animal models, and shed light on the ability of canine models to facilitate current and future treatment trials.

Long-term outcomes of systemic therapies for Hurler syndrome: an international multicenter comparison

PURPOSE

Early treatment is critical for mucopolysaccharidosis type I (MPS I), justifying its incorporation into newborn screening. Enzyme replacement therapy (ERT) treats MPS I, yet presumptions that ERT cannot penetrate the blood-brain barrier (BBB) support recommendations that hematopoietic cell transplantation (HCT) treat the severe, neurodegenerative form (Hurler syndrome). Ethics precludes randomized comparison of ERT with HCT, but insight into this comparison is presented with an international cohort of patients with Hurler syndrome who received long-term ERT from a young age.

METHODS

Long-term survival and neurologic outcomes were compared among three groups of patients with Hurler syndrome: 18 treated with ERT monotherapy (ERT group), 54 who underwent HCT (HCT group), and 23 who received no therapy (Untreated). All were followed starting before age 5 years. A sensitivity analysis restricted age of treatment below 3 years.

RESULTS

Survival was worse when comparing ERT versus HCT, and Untreated versus ERT. The cumulative incidences of hydrocephalus and cervical spinal cord compression were greater in ERT versus HCT. Findings persisted in the sensitivity analysis.

CONCLUSION

As newborn screening widens treatment opportunity for Hurler syndrome, this examination of early treatment quantifies some ERT benefit, supports presumptions about BBB impenetrability, and aligns with current guidelines to treat with HCT.

Beneath the floor: re-analysis of neurodevelopmental outcomes in untreated Hurler syndrome

Background

Hurler syndrome (MPS IH), the severe, neurodegenerative form of type one mucopolysaccharidosis, is associated with rapid neurocognitive decline during toddlerhood and multi-system dysfunction. It is now standardly treated with hematopoietic cell transplantation (HCT), which halts accumulating disease pathology and prevents early death. While norm-based data on developmental functioning in untreated children have previously demonstrated neurocognitive decline, advances in methodology for understanding the cognitive functioning of children with neurodegenerative diseases have highlighted that the previous choice of scores to report results was not ideal. Specifically, the lowest possible norm-based score is 50, which obscures the complete range of cognitive functioning at more advanced stages of neurodeterioration. To a set of cognitive data collected on a sample of untreated children, we applied a modern method of score analysis, calculating a developmental quotient based on age equivalent scores, to reveal the full range of cognitive functioning beneath this cutoff of 50, uncovering new information about the rapidity of decline and the profound impairment in these children.

Results

Among 39 observations for 32 patients with untreated Hurler syndrome, the full array of cognitive functioning below 50 includes many children in the severely to profoundly impaired range. The loss of skills per time unit was 14 points between age 1 and 2. There was a very large range of developmental quotients corresponding to the norm-based cutoff of 50.

Conclusions

This report enables clarification of functioning at levels that extend beneath the floor of 50 in previous work. At the dawn of newborn screening and amidst a proliferation of new therapies for MPS I, these data can provide crucial benchmark information for developing treatments, particularly for areas of the world where transplant may not be available.

Survival in idursulfase-treated and untreated patients with mucopolysaccharidosis type II: data from the Hunter Outcome Survey (HOS)

Mucopolysaccharidosis type II (MPS II; Hunter syndrome; OMIM 309900) is a life-limiting, multisystemic disease with varying presentation and severity. Enzyme replacement therapy with intravenous idursulfase (EC 3.1.6.13) has been available since 2006. Data from the Hunter Outcome Survey (July 2016) were used to compare survival in idursulfase-treated (n = 800) and untreated (n = 95) male patients followed prospectively in this multinational, observational registry. Median age at symptom onset was similar for the treated and untreated groups (1.6 and 1.5 years, respectively), as was median age at diagnosis (3.3 and 3.2 years) and the proportion of patients with cognitive impairment (58.0%; 57.9%). The proportion of idursulfase-treated patients differed according to geographical region. Overall, 124/800 (15.5%) treated and 28/95 (29.5%) untreated patients had died. Respiratory failure was the most common cause of death (treated, 43/124 [34.7%]; untreated, 10/28 [35.7%]). Median survival (95% confidence interval [CI]) was 33.0 (30.4, 38.4) years in treated patients and 21.2 (16.1, 31.5) years in untreated patients; median follow-up time from birth to death or last visit was 13.0 and 15.1 years, respectively. A Cox model adjusted for treatment status, cognitive impairment, region and age at diagnosis indicated a 54% lower risk of death in treated compared with untreated patients: hazard ratio (HR), 0.46 (95% CI: 0.29, 0.72). Patients with cognitive impairment had nearly a fivefold higher risk of death than those without (HR, 4.84 [3.13, 7.47]). This analysis in a large population of patients with MPS II indicates for the first time that idursulfase treatment is associated with increased survival.

Efficacy and safety of intravenous laronidase for mucopolysaccharidosis type I: A systematic review and meta-analysis

Mucopolysaccharidosis type I (MPS I) is an autosomal recessive disease caused by deficient activity of alpha-L-iduronidase. Intravenous (IV) enzyme replacement therapy (ERT) with laronidase is currently used for treating patients with MPS I.

Mucopolysaccharidosis type I, II and VI and response to enzyme replacement therapy: Results from a single-center case series study

Mucopolysaccharidoses (MPS) types I, II and VI are associated with deficiencies in alpha-L-iduronidase, iduronate-2-sulfatase and N-acetylgalactosamine-4-sulfatase, respectively, and generally involve progressive and multi-systemic clinical manifestations. Enzyme replacement therapy (ERT) appears to be reasonably well tolerated. The aim of this study was to examine clinical and diagnostic findings of a series of pediatric and adult MPS patients, and assess the safety and efficacy of ERT in children and adults with MPS type I, II and VI. Pediatric and adult patients were treated weekly with 1 mg/kg recombinant human N-acetylgalactosamine-4-sulphatase (rhASB), 0.45 mg/kg alpha-L-iduronidase, or 0.5 mg/kg iduronate-2-sulfatase. Clinical and biochemical parameters with ERT were evaluated for a mean duration of 5 years. Mantel-Haenszel risk ratios and associated 95% confidence intervals (CIs) were calculated for rates of death among different types of enzyme replacement therapies (ERTs). Twenty-seven patients (mean ages ‒ pediatric: 6.8 years; adult: 29 years) were included. ERT was found to be consistently well tolerated and effective in attenuating symptoms, but did not prevent the progression of the disease or reduce mortality rates. Our findings demonstrated that early diagnosis and initiation of ERT are critical for improvements in patient-important outcomes and quality of life, although disease progression and mortality rates remain high.

Immune tolerance induction for laronidase treatment in mucopolysaccharidosis I

Enzyme replacement therapy (ERT) can produce anti-drug antibody (ADA) responses that reduce efficacy or lead to hypersensitivity reactions. Six patients with severe mucopolysaccharidosis type I (MPS I/Hurler syndrome) who did not receive hematopoietic stem cell transplantation underwent an immunosuppression regimen prior to initiating ERT with laronidase. The primary endpoint for immune tolerance induction was the number of patients with an ADA titer ≤ 3200 after 24 weeks of laronidase at the labeled dose. Cyclosporine levels were measured weekly and doses adjusted to maintain trough levels above 400 mg/mL. A 6-week (Cohort 1) or 12-week (Cohort 2) immune tolerance induction period with cyclosporine (initial dose: 15 or 20 mg/kg/day), azathioprine (initial dose: 2.5 or 5 mg/kg/day) and low-dose laronidase infusions (0.058–0.29 mg/kg/week) was followed by an immune-challenge period with laronidase infusions at the labeled dose (0.58 mg/kg/week) for 24 weeks. Anti-laronidase IgG titers were determined following treatment. There were 147 treatment-emergent adverse events reported, most of which were mild and not related to the study treatment. While there was no evidence of immune tolerance in 3 of 3 patients in Cohort 1, there were some indications of immune tolerance induction in 2 of 3 patients in Cohort 2. Patients with lower ADA titers showed greater reductions in urinary glycosaminoglycan excretion. Routine monitoring of plasma cyclosporine parent-compound levels by high pressure liquid chromatography proved difficult for clinical practice. The evolving clinical management of MPS I and a better understanding of the clinical impact of laronidase-related immunogenicity require reassessment of immune modulation strategies in patients with MPS I receiving laronidase treatment. Clinical Trial Registration: NCT00741338.

Thoracolumbar kyphosis in patients with mucopolysaccharidoses: clinical outcomes and predictive radiographic factors for progression of deformity

AIMS

Clinical and radiological data were reviewed for all patients with mucopolysaccharidoses (MPS) with thoracolumbar kyphosis managed non-operatively or operatively in our institution.

METHODS

In all 16 patients were included (eight female: eight male; 50% male), of whom nine had Hurler, five Morquio and two Hunter syndrome. Six patients were treated non-operatively (mean age at presentation of 6.3 years; 0.4 to 12.9); mean kyphotic progression +1.5(o)/year; mean follow-up of 3.1 years (1 to 5.1) and ten patients operatively (mean age at presentation of 4.7 years; 0.9 to 14.4); mean kyphotic progression 10.8(o)/year; mean follow-up of 8.2 years; 4.8 to 11.8) by circumferential arthrodesis with posterior instrumentation in patients with flexible deformities (n = 6).

RESULTS

In the surgical group (mean age at surgery of 6.6 years; 2.4 to 16.8); mean post-operative follow-up of 6.3 years (3.5 to 10.3), mean pre-operative thoracolumbar kyphosis of 74.3(o) (42(o) to 110(o)) was corrected to mean of 28.6(o) (0(o) to 65(o)) post-operatively, relating to a mean deformity correction of 66.9% (31% to 100%). Surgical complications included a deep wound infection treated by early debridement, apical non-union treated by posterior re-grafting, and stable adjacent segment spondylolisthesis managed non-operatively. Thoracolumbar kyphosis > +38(o) at initial presentation was identified as predicting progressively severe deformity with 90% sensitivity and 83% specificity.

DISCUSSION

This study demonstrates that severe thoracolumbar kyphosis in patients with MPS can be effectively treated by circumferential arthrodesis. Severity of kyphosis at initial presentation may predict progression of thoracolumbar deformity. Patients with MPS may be particularly susceptible to post-operative complications due to the underlying connective tissue disorder and inherent immunological compromise.

TAKE HOME MESSAGE

Clinical and radiological data were reviewed for all patients with mucopolysaccharidoses with thoracolumbar kyphosis managed non-operatively or operatively in our institution.

Personalized Pharmacoperones for Lysosomal Storage Disorder: Approach for Next-Generation Treatment

Lysosomal storage disorders (LSDs) are a collection of inborn errors of metabolic disorders affected by mutations in lysosome functional genes, commonly acid hydrolases. From the past decades, many approaches like enzyme replacement therapy, substrate reduction therapy are followed to treat these conditions. However, all these approaches have their own limitations. Proof-of-concept studies on pharmacological chaperone therapy (PCT) is now transformed into clinical practice to treat LSDs. Furthermore, it is narrowed with individuals to chaperone sensitive, specific mutations. Hence, personalizing the PCT will be a new direction to combat LSDs. In this review, we have discussed the available clinical strategies and pointed the light on how pharmacological chaperones can be personalized and hopeful to be a next-generation approach to address LSDs.