Effect of anti-laronidase antibodies on efficacy and safety of laronidase enzyme replacement therapy for MPS I: A comprehensive meta-analysis of pooled data from multiple studies

N-glycan-modified α-L-iduronidase produced by transgenic silkworms ameliorates clinical signs in a Japanese macaque with mucopolysaccharidosis I

BACKGROUND

Mucopolysaccharidosis type I (MPS I) is an inherited lysosomal storage disorder (LSD) caused by recessive mutations in the α-L-iduronidase (IDUA) gene. Enzyme replacement therapy (ERT) utilizing terminal mannose-6-phosphate (M6P)-carrying N-glycans attached to therapeutic enzymes produced by mammalian cell lines has been clinically applied to several LSDs. Recent studies suggested an unidentified delivery pathway mediated by sialic acid-containing N-glycans. However, more economical platform development is required to produce large quantities of recombinant enzymes. Transgenic silkworms have been established as low-cost systems for expressing recombinant glycoproteins. Microbial endo-β-N-acetylglucosaminidases (ENGases) enable the transglycosylation of N-glycans to other types.

METHODS

We purified recombinant human IDUA from IDUA transgenic silkworm cocoons and performed ENGase-mediated transglycosylation. Furthermore, we performed intravenous enzyme replacement therapy in a Japanese macaque MPS I non-human primate model carrying a homozygous IDUA missense mutation.

RESULTS

Here we show the establishment of IDUA transgenic silkworms and purification of recombinant human IDUA from cocoons. As M6P- and sialic acid-containing N-glycans are not attached to purified hIDUA, we perform ENGase-mediated transglycosylation to obtain hIDUAs with M6P- and sialic acid-containing N-glycans (neoglyco-hIDUAs). Furthermore, we perform intravenous neoglyco-hIDUA replacement therapy in MPS I non-human primate model and succeed in improving the clinical signs and reducing the urinary glycosaminoglycan (GAG) levels.

CONCLUSIONS

These glycotechnologies using transgenic silkworms and ENGases are expected to serve as platforms for developing therapeutic glycoproteins.

Clinical characteristics and long-term prognosis of 150 children with MELAS syndrome in China

OBJECTIVE

The aim was to summarise the clinical characteristics of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS), evaluate patient survival status, and identify prognostic factors.

METHODS

This retrospective study enrolled 150 children with MELAS from 07/2004 to 07/2023. The patients were followed up for a median of 3.37 years (IQR: 2.07-6.16 years). Disease burden was assessed using the Newcastle Pediatric Mitochondrial Disease Scale (NPMDS), and Spearman's correlation coefficient was used to analyse factors affecting disease severity. The Kaplan-Meier and Cox proportional methods were used for survival analysis.

RESULTS

Overall, 150 patients (73 male) were enrolled, of whom 118 were followed up and 22 died. The mean age at onset was 8.2 years (0.4-15.3), and stroke-like episodes were the most common initial symptoms (54%). Among the surviving patients, 78 completed the NPMDS (mean score: 23.6 ± 6.7 points), and 71.8% (56/78) had moderate-to-severe disease (NPMDS score ≥ 15 points). The NPMDS score was positively correlated with disease duration (r = 0.41, P < 0.001) and negatively correlated with age at onset (r =  -0.26, P < 0.01). Among 48 patients who received long-term oral L-arginine and anti-seizure medications (ASMs), 56.3% (27/48) experienced reductions in seizures and stroke-like episodes. The 10- and 15-year survival rates were 65.3% and 34.5%, respectively. Muscle weakness was an independent risk factor for death (HR = 4.83, 95% CI 1.32-17.68; P = 0.017).

CONCLUSIONS

This study had the largest cohort and longest follow-up of pediatric MELAS. Early onset was associated with severe disease, while muscle weakness was associated with a worse prognosis. Early identification and effective management of stroke-like episodes and seizures are crucial to reduce the disease burden.

Antibodies to recombinant human alpha-L-iduronidase prevent disease correction in cortical bone in MPS I mice

Mucopolysaccharidosis I (MPS I) is a lysosomal storage disorder caused by deficiency of the enzyme α-l-iduronidase (IDUA). Failure of enzyme replacement therapy (ERT) to treat skeletal disease may be due to development of anti-IDUA antibodies, found previously to alter tissue distribution of ERT in animal models. To test this hypothesis, immunocompromised (non-obese diabetic [NOD]-severe combined immunodeficiency [SCID]) MPS I mice were treated with weekly ERT from birth (ERT alone). Some mice also received weekly injections of rabbit immunoglobulin G (IgG) against IDUA (immunized rabbit immune globulin [IRIG]) concomitant with ERT, imitating antibodies developed in patients (ERT+IRIG). Mice treated with ERT+IRIG showed lower IDUA activity and higher disease burden than mice treated with ERT alone in most tissues. Femora were harvested at 20 weeks for ex vivo microcomputed tomography (μCT). Femoral cortical bone thickness and cortical bone area in MPS I mice were greater than in unaffected mice. Mice treated with ERT alone had values that were statistically indistinguishable from carrier mice, while mice that received ERT+IRIG had no significant differences compared to vehicle-treated MPS I mice. The data suggests that immune-modulatory or immune-suppressive therapy to prevent or reduce the humoral immune response against ERT may improve treatment of skeletal disease due to MPS I.

Discovery of allosteric regulators with clinical potential to stabilize alpha-L-iduronidase in mucopolysaccharidosis type I

Mucopolysaccharidosis type I (MPS I) is an inherited lysosomal disease caused by lowered activity of the enzyme alpha-L-iduronidase (IDUA). Current therapeutic options show limited efficacy and do not treat some important aspects of the disease. Therefore, it may be advantageous to identify strategies that could improve the efficacy of existing treatments. Pharmacological chaperones are small molecules that protect proteins from degradation, and their use in combination with enzyme replacement therapy (ERT) has been proposed as an alternative therapeutic strategy. Using the SEE-Tx® proprietary computational drug discovery platform, a new allosteric ligand binding cavity in IDUA was identified distal from the active site. Virtual high-throughput screening of approximately 5 million compounds using the SEE-Tx® docking platform identified a subset of small molecules that bound to the druggable cavity and functioned as novel allosteric chaperones of IDUA. Experimental validation by differential scanning fluorimetry showed an overall hit rate of 11.4%. Biophysical studies showed that one exemplary hit molecule GT-01803 bound to (Kd = 22 μM) and stabilized recombinant human IDUA (rhIDUA) in a dose-dependent manner. Co-administration of rhIDUA and GT-01803 increased IDUA activity in patient-derived fibroblasts. Preliminary in vivo studies have shown that GT-01803 improved the pharmacokinetic (PK) profile of rhIDUA, increasing plasma levels in a dose-dependent manner. Furthermore, GT-01803 also increased IDUA enzymatic activity in bone marrow tissue, which benefits least from standard ERT. Oral bioavailability of GT-01803 was found to be good (50%). Overall, the discovery and validation of a novel allosteric chaperone for rhIDUA presents a promising strategy to enhance the efficacy of existing treatments for MPS I. The compound's ability to increase rhIDUA activity in patient-derived fibroblasts and its good oral bioavailability underscore its potential as a potent adjunct to ERT, particularly for addressing aspects of the disease less responsive to standard treatment.

[Inborn error of metabolism and allogenic hematopoietic cell transplantation: Guidelines from the SFGM-TC]

Inherited Metabolic Diseases (IMD) are rare genetic diseases, including both lysosomal and peroxisomal diseases. Lysosomal diseases are related to the deficiency of one or more lysosomal enzymes or transporter. Lysosomal diseases are progressive and involve several tissues with most often neurological damage. Among peroxisomal diseases, X-linked adrenoleukodystrophy (ALD) is a neurodegenerative disease combining neurological and adrenal damage. For these diseases, enzyme replacement therapy (ERT), allogeneic hematopoietic cell transplantation (allo-HCT) and gene therapy represent various possible treatment options, used alone or in combination. The purpose of this workshop is to describe the indications, modalities, and follow-up of allo-HCT as well as the use of ERT peri-transplant. All indications for transplant in these rare diseases are associated with comorbidities and are subject to criteria that must be discussed in a dedicated national multidisciplinary consultation meeting. There are some consensual indications in type I-H mucopolysaccharidosis (MPS-IH) and in the cerebral form of ALD. For other IMDs, no clear benefit from the transplant has been demonstrated. The ideal donor is a non-heterozygous HLA-identical sibling. The recommended conditioning is myeloablative combining fludarabine and busulfan. In MPS-IH, ERT has to be started at diagnosis and continued until complete chimerism and normal enzyme assay are achieved. The pre-transplant assessment and post-transplant follow-up are made according to the published recommendations (PNDS). Standard follow-up is carried out jointly by the transplant and referral teams.

Blood-brain barrier delivery for lysosomal storage disorders with IgG-lysosomal enzyme fusion proteins

The majority of lysosomal storage diseases affect the brain. Treatment of the brain with intravenous enzyme replacement therapy is not successful, because the recombinant lysosomal enzymes do not cross the blood-brain barrier (BBB). Biologic drugs, including lysosomal enzymes, can be re-engineered for BBB delivery as IgG-enzyme fusion proteins. The IgG domain of the fusion protein is a monoclonal antibody directed against an endogenous receptor-mediated transporter at the BBB, such as the insulin receptor or the transferrin receptor. This receptor transports the IgG across the BBB, in parallel with the endogenous receptor ligand, and the IgG acts as a molecular Trojan horse to ferry into brain the lysosomal enzyme genetically fused to the IgG. The IgG-enzyme fusion protein is bi-functional and retains both high affinity binding for the BBB receptor, and high lysosomal enzyme activity. IgG-lysosomal enzymes are presently in clinical trials for treatment of the brain in Mucopolysaccharidosis.

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.

Retrospective chart review of urinary glycosaminoglycan excretion and long-term clinical outcomes of enzyme replacement therapy in patients with mucopolysaccharidoses

BACKGROUND

Mucopolysaccharidoses (MPS) are a group of rare, inherited metabolic diseases that result from a deficiency in one of several lysosomal enzymes essential for stepwise glycosaminoglycan (GAG) degradation, leading to GAG accumulation and widespread cellular pathology and clinical disease. Although disease presentation is heterogeneous, the clinical hallmarks are largely comparable across several MPS subtypes. Extensive data have shown that the level of urinary GAG (uGAG) excretion above normal is strongly correlated with disease severity and clinical outcomes in MPS diseases. Thus, change in uGAG excretion may have significant value as a potential primary endpoint in clinical trials of MPS diseases that are too rare to study using traditional clinical endpoints.

METHODS

A retrospective medical chart review was undertaken of patients with MPS I, II, and VI who had been treated long term with enzyme replacement therapy (ERT). The relationship between uGAG reduction and clinical outcomes relevant to the major clinical manifestations of these MPS diseases was evaluated. A multi-domain responder index (MDRI) score was calculated, measuring the following 4 domains: 6-min walk test, pulmonary function, growth rate, and Clinician Global Impression of Change. For each domain, a minimal important difference (MID) was defined based on published information of these outcome measures in MPS and other diseases.

RESULTS

Of the 50 patients evaluated, 18 (36%) had MPS I, 23 (46%) had MPS II, and 9 (18%) had MPS VI. Forty-two were clinical practice patients and 8 had participated in clinical trials. Across all MPS subtypes, the mean (± SD) uGAG level at baseline was 66.0 ± 51.5 mg/mmol creatinine (n = 48) and there was a mean reduction of 54.6% following ERT. Analysis of the MDRI score based on the MID defined for each domain showed a greater magnitude of improvement in patients with increased uGAG reduction when compared with those patients with lower uGAG reduction for all assessed uGAG thresholds, and a trend toward a higher likelihood of positive mean MDRI score in patients with a uGAG reduction ≥40%.

CONCLUSIONS

In this retrospective study, uGAG reduction was associated with long-term clinical outcomes as assessed by a number of approaches, supporting the use of uGAG reduction as a biomarker primary endpoint.

Enzyme therapy: a forerunner in catalyzing a healthy society?

INTRODUCTION

The use of enzymes in various industries has been prevalent for centuries. However, their potency as therapeutics remained latent until the late 1950 s, when scientists finally realized the gold mine they were sitting on. Enzyme therapy has seen rapid development over the past few decades and has been widely used for the therapy of myriad diseases, including lysosomal storage disorders, cancer, Alzheimer's disease, irritable bowel syndrome, exocrine pancreatic insufficiency, and hyperuricemia. Enzymes are also used for wound healing, the treatment of microbial infections, and gene therapy.

AREAS COVERED

This is a comprehensive review of the therapeutic use of enzymes that can act as a guidepost for researchers and academicians and presents a general overview of the developments in enzyme therapy over the years, along with updates on recent advancements in enzyme therapy research.

EXPERT OPINION

Although enzyme therapy is immensely beneficial and induces little auxiliary damage, it has several drawbacks, ranging from high cost, low stability, low production, and hyperimmune responses to the failure to cure a variety of the problems associated with a disease. Further fine-tuning and additional clinical efficacy studies are required to establish enzyme therapy as a forerunner to catalyzing a healthy society.

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.

Targeting Macromolecules to CNS and Other Hard-to-Treat Organs Using Lectin-Mediated Delivery

The greatest challenges for therapeutic efficacy of many macromolecular drugs that act on intracellular are delivery to key organs and tissues and delivery into cells and subcellular compartments. Transport of drugs into critical cells associated with disease, including those in organs protected by restrictive biological barriers such as central nervous system (CNS), bone, and eye remains a significant hurdle to drug efficacy and impacts commercial risk and incentives for drug development for many diseases. These limitations expose a significant need for the development of novel strategies for macromolecule delivery. RTB lectin is the non-toxic carbohydrate-binding subunit B of ricin toxin with high affinity for galactose/galactosamine-containing glycolipids and glycoproteins common on human cell surfaces. RTB mediates endocytic uptake into mammalian cells by multiple routes exploiting both adsorptive-mediated and receptor-mediated mechanisms. In vivo biodistribution studies in lysosomal storage disease models provide evidence for the theory that the RTB-lectin transports corrective doses of enzymes across the blood–brain barrier to treat CNS pathologies. These results encompass significant implications for protein-based therapeutic approaches to address lysosomal and other diseases having strong CNS involvement.

Clinical trial of laronidase in Hurler syndrome after hematopoietic cell transplantation

BACKGROUND

Mucopolysaccharidosis I (MPS IH) is a lysosomal storage disease treated with hematopoietic cell transplantation (HCT) because it stabilizes cognitive deterioration, but is insufficient to alleviate all somatic manifestations. Intravenous laronidase improves somatic burden in attenuated MPS I. It is unknown whether laronidase can improve somatic disease following HCT in MPS IH. The objective of this study was to evaluate the effects of laronidase on somatic outcomes of patients with MPS IH previously treated with HCT.

METHODS

This 2-year open-label pilot study of laronidase included ten patients (age 5-13 years) who were at least 2 years post-HCT and donor engrafted. Outcomes were assessed semi-annually and compared to historic controls.

RESULTS

The two youngest participants had a statistically significant improvement in growth compared to controls. Development of persistent high-titer anti-drug antibodies (ADA) was associated with poorer 6-min walk test (6MWT) performance; when patients with high ADA titers were excluded, there was a significant improvement in the 6MWT in the remaining seven patients.

CONCLUSIONS

Laronidase seemed to improve growth in participants <8 years old, and 6MWT performance in participants without ADA. Given the small number of patients treated in this pilot study, additional study is needed before definitive conclusions can be made.

Enzyme replacement therapy for mucopolysaccharidoses; past, present, and future

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders, which lack an enzyme corresponding to the specific type of MPS. Enzyme replacement therapy (ERT) has been the standard therapeutic option for some types of MPS because of the ability to start immediate treatment with feasibility and safety and to improve prognosis. There are several disadvantages for current ERT, such as limited impact to the brain and avascular cartilage, weekly or biweekly infusions lasting 4-5 h, the immune response against the infused enzyme, a short half-life, and the high cost. Clinical studies of ERT have shown limited efficacy in preventing or resolving progression in neurological, cardiovascular, and skeletal diseases. One focus is to penetrate the avascular cartilage area to at least stabilize, if not reverse, musculoskeletal diseases. Although early intervention in some types of MPS has shown improvements in the severity of skeletal dysplasia and stunted growth, this limits the desired effect of ameliorating musculoskeletal disease progression to young MPS patients. Novel ERT strategies are under development to reach the brain: (1) utilizing a fusion protein with monoclonal antibody to target a receptor on the BBB, (2) using a protein complex from plant lectin, glycan, or insulin-like growth factor 2, and (3) direct infusion across the BBB. As for MPS IVA and VI, bone-targeting ERT will be an alternative to improve therapeutic efficacy in bone and cartilage. This review summarizes the effect and limitations on current ERT for MPS and describes the new technology to overcome the obstacles of conventional ERT.

Therapeutic Options for Mucopolysaccharidoses: Current and Emerging Treatments

Mucopolysaccharidoses (MPS) are inborn errors of metabolism produced by a deficiency of one of the enzymes involved in the degradation of glycosaminoglycans (GAGs). Although taken separately, each type is rare. As a group, MPS are relatively frequent, with an overall estimated incidence of around 1 in 20,000-25,000 births. Development of therapeutic options for MPS, including hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy (ERT), has modified the natural history of many MPS types. In spite of the improvement in some tissues and organs, significant challenges remain unsolved, including blood-brain barrier (BBB) penetration and treatment of lesions in avascular cartilage, heart valves, and corneas. Newer approaches, such as intrathecal ERT, ERT with fusion proteins to cross the BBB, gene therapy, substrate reduction therapy (SRT), chaperone therapy, and some combination of these strategies may provide better outcomes for MPS patients in the near future. As early diagnosis and early treatment are imperative to improve therapeutic efficacy, the inclusion of MPS in newborn screening programs should enhance the potential impact of treatment in reducing the morbidity associated with MPS diseases. In this review, we evaluate available treatments, including ERT and HSCT, and future treatments, such as gene therapy, SRT, and chaperone therapy, and describe the advantages and disadvantages. We also assess the current clinical endpoints and biomarkers used in clinical trials.

Post-transplant laronidase augmentation for children with Hurler syndrome: biochemical outcomes

Allogeneic hematopoietic cell transplantation (HCT) benefits children with Hurler syndrome (MPS-IH). However, survivors remain burdened by substantial MPS-IH related residual disease. We studied the feasibility, safety and biochemical impact of augmentative recombinant intravenous enzyme replacement therapy (IV-ERT) post transplantation. Ten children with MPS-IH and ≥2 years from successful HCT underwent IV-ERT for 2 years’ duration. Patients were monitored for anti-drug antibody (ADA) development, including inhibitory capacity and changes in urinary excretion of glycosaminoglycans (uGAG). Three patients demonstrated low-level ADA at baseline, though all children tolerated IV-ERT well. Eight patients developed ADA over the 2-year study, with 3 (38%) meeting criteria for an inhibitory ADA response. The aggregate cohort experienced a reduction in uGAG from baseline to study end, which was enhanced in children with low or no ADA response. Conversely, children with inhibitory ADA showed increase in uGAG over time. IV-ERT in previously transplanted children with MPS-IH appears safe and can reduce uGAG, although this is reversed by the presence of inhibitory ADA. These data show a biochemical change after initiation of post-HCT IV-ERT, but the occurrence of ADA and inhibitory antibodies are a concern and should be monitored in future efficacy trials. This trial was registered at www.clinicaltrials.gov, NCT01173016, 07/30/2010.

Targeting a Pre-existing Anti-transgene T Cell Response for Effective Gene Therapy of MPS-I in the Mouse Model of the Disease

Mucopolysaccharidosis type I (MPS-I) is a severe genetic disease caused by a deficiency of the alpha-L-iduronidase (IDUA) enzyme. Ex vivo hematopoietic stem cell (HSC) gene therapy is a promising therapeutic approach for MPS-I, as demonstrated by preclinical studies performed in naive MPS-I mice. However, after enzyme replacement therapy (ERT), several MPS-I patients develop anti-IDUA immunity that may jeopardize ex vivo gene therapy efficacy. Here we treat MPS-I mice with an artificial immunization protocol to mimic the ERT effect in patients, and we demonstrate that IDUA-corrected HSC engraftment is impaired in pre-immunized animals by IDUA-specific CD8⁺ T cells spared by pre-transplant irradiation. Conversely, humoral anti-IDUA immunity does not impact on IDUA-corrected HSC engraftment. The inclusion of lympho-depleting agents in pre-transplant conditioning of pre-immunized hosts allowes rescue of IDUA-corrected HSC engraftment, which is proportional to CD8⁺ T cell eradication. Overall, these data demonstrate the relevance of pre-existing anti-transgene T cell immunity on ex vivo HSC gene therapy, and they suggest the application of tailored immune-depleting treatments, as well as a deeper immunological characterization of patients, to safeguard the therapeutic effects of ex vivo HSC gene therapy in immunocompetent hosts.

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.

Plasma Pharmacokinetics of Valanafusp Alpha, a Human Insulin Receptor Antibody-Iduronidase Fusion Protein, in Patients with Mucopolysaccharidosis Type I

BACKGROUND

Mucopolysaccharidosis type I (MPSI) is caused by mutations in the gene encoding the α-L-iduronidase (IDUA) lysosomal enzyme and the majority of MPSI patients have severe central nervous system (CNS) involvement. Enzyme replacement therapy (ERT) with recombinant IDUA does not treat the CNS, due to the lack of transport of the enzyme across the blood-brain barrier (BBB). Human IDUA has been re-engineered as an IgG-IDUA fusion protein, valanafusp alpha, where the IgG domain is a monoclonal antibody (MAb) against the human insulin receptor (HIR). The HIRMAb domain binds the endogenous insulin receptor on the human BBB to trigger receptor-mediated transport across the BBB, and acts as a molecular Trojan horse to ferry the fused IDUA into the brain of patients with MPSI.

METHODS

The present investigation describes the initial dosing, plasma pharmacokinetics, and plasma glucose response to the intravenous infusion of doses of valanafusp alpha ranging from 0.3 to 3 mg/kg in five adults and from 1 to 6 mg/kg in 13 pediatric subjects with MPSI.

RESULTS

Valanafusp alpha plasma clearance is increased four-fold in children, and shows a linear pharmacokinetic response over the dose range of 0.3-3 mg/kg with a stable plasma elimination half-life (t_½). The plasma pharmacokinetic parameters for valanafusp alpha overlapped with the same parameters previously reported for recombinant human IDUA (laronidase). The majority of the tested subjects had been receiving laronidase ERT for years, and some showed high levels of anti-drug antibodies (ADAs). However, the presence of these ADAs did not generally alter the rate of plasma clearance of valanafusp alpha in MPSI. The infusion of 0.3-6 mg/kg doses of valanafusp alpha had no effect on plasma glucose for up to 24 h after the drug infusion.

CONCLUSION

The plasma clearance of valanafusp alpha is increased four-fold in children with MPSI compared with adult subjects at a dose of 1-3 mg/kg. The plasma pharmacokinetic profile of valanafusp alpha, at a dose of 1-3 mg/kg, is comparable to that of laronidase in children with MPSI.

Neurocognitive and somatic stabilization in pediatric patients with severe Mucopolysaccharidosis Type I after 52 weeks of intravenous brain-penetrating insulin receptor antibody-iduronidase fusion protein (valanafusp alpha): an open label phase 1-2 trial

BACKGROUND

Mucopolysaccharidosis (MPS) Type I (MPSI) is caused by mutations in the gene encoding the lysosomal enzyme, α-L-iduronidase (IDUA), and a majority of patients present with severe neurodegeneration and cognitive impairment. Recombinant IDUA does not cross the blood-brain barrier (BBB). To enable BBB transport, IDUA was re-engineered as an IgG-IDUA fusion protein, valanafusp alpha, where the IgG domain targets the BBB human insulin receptor to enable transport of the enzyme into the brain. We report the results of a 52-week clinical trial on the safety and efficacy of valanafusp alpha in pediatric MPSI patients with cognitive impairment. In the phase I trial, 6 adults with attenuated MPSI were administered 0.3, 1, and 3 mg/kg doses of valanafusp alpha by intravenous (IV) infusion. In the phase II trial, 11 pediatric subjects, 2-15 years of age, were treated for 52 weeks with weekly IV infusions of valanafusp alpha at 1, 3, or 6 mg/kg. Assessments of adverse events, cognitive stabilization, and somatic stabilization were made. Outcomes at 52 weeks were compared to baseline.

RESULTS

Drug related adverse events included infusion related reactions, with an incidence of 1.7%, and transient hypoglycemia, with an incidence of 6.4%. The pediatric subjects had CNS involvement with a mean enrollment Development Quotient (DQ) of 36.1±7.1. The DQ, and the cortical grey matter volume of brain, were stabilized by valanafusp alpha treatment. Somatic manifestations were stabilized, or improved, based on urinary glycosaminoglycan levels, hepatic and spleen volumes, and shoulder range of motion.

CONCLUSION

Clinical evidence of the cognitive and somatic stabilization indicates that valanafusp alpha is transported into both the CNS and into peripheral organs due to its dual targeting mechanism via the insulin receptor and the mannose 6-phosphate receptor. This novel fusion protein offers a pharmacologic approach to the stabilization of cognitive function in MPSI.

TRIAL REGISTRATION

Clinical Trials.Gov, NCT03053089 . Retrospectively registered 9 February, 2017; Clinical Trials.Gov, NCT03071341 . Registered 6 March, 2017.

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.

Efficacy of laronidase therapy in patients with mucopolysaccharidosis type I who initiated enzyme replacement therapy in adult age. A systematic review and meta-analysis

BACKGROUND

The efficacy of starting enzyme replacement therapy (ERT) in adults with Muchopolysaccharidosis Type I (MPS-I) is controversial. Evaluating the benefits reported by patients initiating ERT with laronidase at adult age might help physicians decide whether the use of ERT in these patients is worthwhile from a clinical point of view.

OBJECTIVE

To assess every effectiveness variable modified in MPS-I patients who initiated laronidase at adult age.

METHODS

A systematic search of the literature, from inception to July 2016, was conducted using MEDLINE, EMBASE, CENTRAL and LILACS to identify randomized trials or observational studies including ≥1 MPS-I patients with ERT initiated in adult age (≥18years) and evaluating ERT efficacy. A meta-analysis of studies evaluating the same effectiveness outcome was performed and the evidence was rated according to GRADE criteria. Heterogeneity was assessed by the Chi-squared test and the I-squared statistic. Case reports were excluded from meta-analysis but their main outcomes were separately evaluated. The decrease in urine glycosaminoglycans (uGAGs) levels as patient percentage with reduction in uGAGs and with normalization was the primary outcome.

RESULTS

Nineteen clinical studies and 12 case reports were selected. ERT decreased uGAG levels (high evidence) and liver volume (high), improved 6-min walking test (6MWT) (moderate) and increased blood anti-ERT antibody levels (high). There was no conclusive results (low or very low evidence) regarding improvement/stabilization of respiratory function, change in shoulder flexion, cardiac improvement/stabilization, improvement in symptoms of nocturnal hypoventilation and sleep apnea, improvement in quality of life, visual acuity, otolaryngologic function, bone mineral density or effectiveness of intrathecal therapy.

LIMITATIONS

Excluding case reports, there was no study conducted specifically in the target population (ERT ≥18years). Data were from subgroup analyses of selected studies. There was a great heterogeneity between designs and clinical outcomes evaluated.

CONCLUSIONS

ERT improves uGAGs and liver volume in MPS-I patients initiating therapy as adults, although the putative clinical benefit associated to these improvements is unclear. Moderate evidence was shown for improvement in 6MWT. Systematic review registration number (PROSPERO): 42,016,041,306.

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.

Long-term Immunogenicity of Elosulfase Alfa in the Treatment of Morquio A Syndrome: Results From MOR-005, a Phase III Extension Study

PURPOSE

Elosulfase alfa is an enzyme replacement therapy for the treatment of Morquio A syndrome (mucopolysaccharidosis IVA), a lysosomal storage disorder caused by a deficiency of the enzyme N-acetylgalactose-amine-6-sulfatase. We previously reported immunogenicity data from our 24-week placebo-controlled Phase III study, MOR-004. Here, we report the long-term immunogenicity profile of elosulfase alfa from MOR-005, the Phase III extension trial to assess potential correlations between antidrug antibodies and efficacy and safety profile outcomes throughout 120 weeks of treatment.

METHODS

The long-term immunogenicity of elosulfase alfa was evaluated in patients with Morquio A syndrome in an open-label extension study for a total of 120 weeks. All patients received 2.0 mg/kg elosulfase alfa either weekly or every other week before establishment of 2.0 mg/kg/wk as the recommended dose, at which time all patients received weekly treatment. Efficacy measures were compared with those from the MOR-004 baseline, enabling analysis of changes over 120 weeks. The primary efficacy measure was the change from baseline in 6-minute walk test. Secondary measures included changes from baseline in 3-minute stair climb test and normalized urine keratan sulfate, a pharmacodynamic metric.

FINDINGS

All patients treated with elosulfase alfa developed antidrug total antibodies (TAb) by week 24 of MOR-004. In the extension study, all patients, including those who had previously received placebo, were TAb positive by study week 36 (MOR-005 week 12). All patients remained TAb positive throughout the study, and TAb titers were similar across treatment groups at week 120. Nearly all patients tested positive for neutralizing antibodies (NAb) at least once, with incidence of NAb positivity peaking at 85.9% at study week 36, then steadily declining to 66.0% at study week 120. In all treatment groups, mean urine keratan sulfate remained below treatment-naive baseline despite the presence of antidrug antibodies. No relationship was observed between TAb titers or NAb positivity and changes in urine keratan sulfate, 6-minute walk test, or 3-minute stair climb test from baseline to week 120. No consistent associations were detected between antidrug antibodies and the occurrence of hypersensitivity adverse events or anaphylaxis over the course of the study.

IMPLICATIONS

Immunogenicity results from this long-term study are consistent with previously reported 24-week results. Despite the sustained presence of antidrug antibodies, elosulfase alfa was well tolerated, and patients continued to benefit from treatment through week 120. No associations were detected between higher TAb titers or NAb positivity and reduced treatment effect or worsened safety profile measures. ClinicalTrials.gov identifier: NCT01415427.