α-L-iduronidase fused with humanized anti-human transferrin receptor antibody (lepunafusp alfa) for mucopolysaccharidosis type I: A phase 1/2 trial.

Mucopolysaccharidosis type I (MPS I) causes systemic accumulation of glycosaminoglycans due to a genetic deficiency of α-L-iduronidase (IDUA), which results in progressive systemic symptoms affecting multiple organs, including the central nervous system (CNS). Because the blood-brain barrier (BBB) prevents enzymes from reaching the brain, enzyme replacement therapy is effective only against the somatic symptoms. Hematopoietic stem cell transplantation can address the CNS symptoms, but the risk of complications limits its applicability. We have developed a novel genetically modified protein consisting of IDUA fused with humanized anti-human transferrin receptor antibody (lepunafusp alfa; JR-171), which has been shown in nonclinical studies to be distributed to major organs, including the brain, bringing about systemic reductions in heparan sulfate (HS) and dermatan sulfate concentrations. Subsequently, a first-in-human study was conducted to evaluate the safety, pharmacokinetics, and exploratory efficacy of JR-171 in 18 patients with MPS I. No notable safety issues were observed. Plasma drug concentration increased dose dependently and reached its maximum approximately 4 h after the end of drug administration. Decreased HS in the cerebrospinal fluid suggested successful delivery of JR-171 across the BBB, while suppressed urine and serum concentrations of the substrates indicated that its somatic efficacy was comparable to that of laronidase.

Transferrin Receptor-Targeted Iduronate-2-sulfatase Penetrates the Blood-Retinal Barrier and Improves Retinopathy in Mucopolysaccharidosis II Mice.

Mucopolysaccharidoses (MPSs) make up a group of lysosomal storage diseases characterized by the aberrant accumulation of glycosaminoglycans throughout the body. Patients with MPSs display various signs and symptoms, such as retinopathy, which is also observed in patients with MPS II. Unfortunately, retinal disorders in MPS II are resistant to conventional intravenous enzyme-replacement therapy because the blood-retinal barrier (BRB) impedes drug penetration. In this study, we show that a fusion protein, designated pabinafusp alfa, consisting of an antihuman transferrin receptor antibody and iduronate-2-sulfatase (IDS), crosses the BRB and reaches the retina in a murine model of MPS II. We found that retinal function, as assessed by electroretinography (ERG) in MPS II mice, deteriorated with age. Early intervention with repeated intravenous treatment of pabinafusp alfa decreased heparan sulfate deposition in the retina, optic nerve, and visual cortex, thus preserving or even improving the ERG response in MPS II mice. Histological analysis further revealed that pabinafusp alfa mitigated the loss of the photoreceptor layer observed in diseased mice. In contrast, recombinant nonfused IDS failed to reach the retina and hardly affected the retinal disease. These results support the hypothesis that transferrin receptor-targeted IDS can penetrate the BRB, thereby ameliorating retinal dysfunction in MPS II.

Enzyme replacement with transferrin receptor-targeted α-L-iduronidase rescues brain pathology in mucopolysaccharidosis I mice.

Mucopolysaccharidosis I (MPS I), a lysosomal storage disease caused by dysfunction of α-L-iduronidase (IDUA), is characterized by the deposition of dermatan sulfate (DS) and heparan sulfate (HS) throughout the body, which causes several somatic and central nervous symptoms. Although enzyme-replacement therapy (ERT) is currently available to treat MPS I, it does not alleviate central nervous disorders, as it cannot penetrate the blood-brain barrier. Here we evaluate the brain delivery, efficacy, and safety of JR-171, a fusion protein comprising humanized anti-human transferrin receptor antibody Fab and IDUA, using monkeys and MPS I mice. Intravenously administered JR-171 was distributed in major organs, including the brain, and reduced DS and HS concentrations in the central nervous system and peripheral tissues. JR-171 exerted similar effects on peripheral disorders similar to conventional ERT and further reversed brain pathology in MPS I mice. We found that JR-171 improved spatial learning ability, which was seen to deteriorate in the vehicle-treated mice. Further, no safety concerns were noted in repeat-dose toxicity studies in monkeys. This study provides nonclinical evidence that JR-171 might potentially prevent and even improve disease conditions in patients with neuronopathic MPS I without serious safety concerns.

Pathogenic Roles of Heparan Sulfate and Its Use as a Biomarker in Mucopolysaccharidoses.

Heparan sulfate (HS) is an essential glycosaminoglycan (GAG) as a component of proteoglycans, which are present on the cell surface and in the extracellular matrix. HS-containing proteoglycans not only function as structural constituents of the basal lamina but also play versatile roles in various physiological processes, including cell signaling and organ development. Thus, inherited mutations of genes associated with the biosynthesis or degradation of HS can cause various diseases, particularly those involving the bones and central nervous system (CNS). Mucopolysaccharidoses (MPSs) are a group of lysosomal storage disorders involving GAG accumulation throughout the body caused by a deficiency of GAG-degrading enzymes. GAGs are stored differently in different types of MPSs. Particularly, HS deposition is observed in patients with MPS types I, II, III, and VII, all which involve progressive neuropathy with multiple CNS system symptoms. While therapies are available for certain symptoms in some types of MPSs, significant unmet medical needs remain, such as neurocognitive impairment. This review presents recent knowledge on the pathophysiological roles of HS focusing on the pathogenesis of MPSs. We also discuss the possible use and significance of HS as a biomarker for disease severity and therapeutic response in MPSs.

Pharmacokinetics and pharmacodynamics of once-weekly administration of JR-142, a long-acting albumin-fused human growth hormone: A rondemized, placebo-controlled phase 1 study.

OBJECTIVE: Under clinical development for patients with growth hormone deficiency, JR-142 is a long-acting growth hormone with a half-life extended by fusion with modified serum albumin. We conducted a Phase 1 study to investigate the safety, tolerability, and pharmacokinetic (PK) and pharmacodynamic (PD) profiles of once-weekly subcutaneous administrations of JR-142. The study consisted of two parts: an open-label single ascending dosing study (Part 1), and a randomized, placebo-controlled, assessor-blinded multiple ascending dosing study (Part 2). DESIGN: A total of 31 healthy Japanese male participants were enrolled. In Part 1, seven of them received a single subcutaneous injection of JR-142 each at dosages of 0.15 mg/kg (n = 1), 0.25 mg/kg (n = 2), 0.5 mg/kg (n = 2), or 1.0 mg/kg (n = 2). In Part 2, one weekly subcutaneous injection of JR-142 at 0.25 mg/kg, 0.5 mg/kg, 1.0 mg/kg or a placebo were given for four weeks to each of the other 24 participants (six in each group). Plasma JR-142 and serum insulin-like growth factor-1 (IGF-1) concentrations were measured for PK and PD assessments. Safety was evaluated on the basis of adverse events (AEs), laboratory tests, and other measures. RESULTS: JR-142 induced dose-dependent increases in the maximum plasma JR-142 concentration (Cmax) and the area under the plasma concentration-time curve from time 0 to τ (AUC0-τ). A similar dose-response relationship was observed in serum IGF-1 concentrations. All trough IGF-1 levels were well sustained one week after the final administrations of JR-142 at the three dosages, while the peak concentrations of IGF-1 remained mildly elevated. No serious AEs were observed, and laboratory tests, including assessment of anti-drug antibodies, uncovered no significant safety issues. CONCLUSIONS: Once-weekly subcutaneous injections of JR-142 produced positive dose-dependent PK and PD profiles over the dosage range. Drug accumulation was observed after the four-week administration period but did not raise safety concerns, indicating that JR-142 is well-tolerated in healthy participants. The PD profiles observed in terms of IGF-1 concentrations were also positive, and we believe the encouraging results of this study warrant substantiation in further clinical trials in patients with GHD. ETHICS: This clinical study was conducted at one investigational site in Osaka, Japan, where the clinical study and the non-clinical data of JR-142 were reviewed and approved by its Institutional Review Board on 9th May 2019. The study was conducted in compliance with the approved study protocol, the Declaration of Helsinki, 1964, as revised in 2013, and Good Clinical Practice.

Dose-dependent effects of a brain-penetrating iduronate-2-sulfatase on neurobehavioral impairments in mucopolysaccharidosis II mice.

Deposition of heparan sulfate (HS) in the brain of patients with mucopolysaccharidosis II (MPS II) is believed to be the leading cause of neurodegeneration, resulting in several neurological signs and symptoms, including neurocognitive impairment. We recently showed that pabinafusp alfa, a blood-brain-barrier-penetrating fusion protein consisting of iduronate-2-sulfatase and anti-human transferrin receptor antibody, stabilized learning ability by preventing the deposition of HS in the CNS of MPS II mice. We further examined the dose-dependent effect of pabinafusp alfa on neurological function in relation to its HS-reducing efficacy in a mouse model of MPS II. Long-term intravenous treatment with low (0.1 mg/kg), middle (0.5 mg/kg), and high (2.0 mg/kg) doses of the drug dose-dependently decreased HS concentration in the brain and cerebrospinal fluid (CSF). A comparable dose-dependent effect in the prevention of neuronal damage in the CNS, and dose-dependent improvements in neurobehavioral performance tests, such as gait analysis, pole test, Y maze, and Morris water maze, were also observed. Notably, the water maze test performance was inversely correlated with the HS levels in the brain and CSF. This study provides nonclinical evidence substantiating a quantitative dose-dependent relationship between HS reduction in the CNS and neurological improvements in MPS II.

Nonclinical safety evaluation of pabinafusp alfa, an anti-human transferrin receptor antibody and iduronate-2-sulfatase fusion protein, for the treatment of neuronopathic mucopolysaccharidosis type II.

Pabinafusp alfa is a fusion protein comprising a humanized anti-human transferrin receptor (TfR) antibody and human iduronate-2-sulfatase. It was developed as a novel modality to target central nervous system-related symptoms observed in patients with mucopolysaccharidosis type II (MPS II, also known as Hunter syndrome). As the fusion protein contains an entire IgG1 molecule that binds TfR, there may be specific safety concerns, such as unexpected cellular toxicity due to its effector functions or its ability to inhibit iron metabolism, in addition to general safety concerns. Here, we present the comprehensive results of a nonclinical safety assessment of pabinafusp alfa. Pabinafusp alfa did not exhibit effector functions, as assessed by antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity studies in TfR-expressing hematopoietic cells. Repeat-dose toxicity studies in cynomolgus monkeys showed that pabinafusp alfa did not induce any significant toxicological changes at doses up to 30 mg/kg/week upon intravenous administration for up to 26 weeks. Interaction of transferrin with TfR was not inhibited by pabinafusp alfa, suggesting that the effect of pabinafusp alfa on the physiological iron transport system is minimal, which was confirmed by toxicity studies in cynomolgus monkeys. These findings suggest that pabinafusp alfa is expected to be safe for long-term use in individuals with MPS II.

Clearance of heparan sulfate in the brain prevents neurodegeneration and neurocognitive impairment in MPS II mice.

Mucopolysaccharidosis II (MPS II), a lysosomal storage disease caused by mutations in iduronate-2-sulfatase (IDS), is characterized by a wide variety of somatic and neurologic symptoms. The currently approved intravenous enzyme replacement therapy with recombinant IDS (idursulfase) is ineffective for CNS manifestations due to its inability to cross the blood-brain barrier (BBB). Here, we demonstrate that the clearance of heparan sulfate (HS) deposited in the brain by a BBB-penetrable antibody-enzyme fusion protein prevents neurodegeneration and neurocognitive dysfunctions in MPS II mice. The fusion protein pabinafusp alfa was chronically administered intravenously to MPS II mice. The drug reduced HS and attenuated histopathological changes in the brain, as well as in peripheral tissues. The loss of spatial learning abilities was completely suppressed by pabinafusp alfa, but not by idursulfase, indicating an association between HS deposition in the brain, neurodegeneration, and CNS manifestations in these mice. Furthermore, HS concentrations in the brain and reduction thereof by pabinafusp alpha correlated with those in the cerebrospinal fluid (CSF). Thus, repeated intravenous administration of pabinafusp alfa to MPS II mice decreased HS deposition in the brain, leading to prevention of neurodegeneration and maintenance of neurocognitive function, which may be predicted from HS concentrations in CSF.

Physicochemical and biological evaluation of JR-131 as a biosimilar to a long-acting erythropoiesis-stimulating agent darbepoetin alfa.

Renal anemia is predominantly caused by a relative deficiency in erythropoietin (EPO). Conventional treatment for renal anemia includes the use of recombinant human EPO (rhEPO) or a long-acting erythropoiesis-activating agent named darbepoetin alfa, which is a modified rhEPO with a carbohydrate chain structure that differs from native hEPO. We have developed a biosimilar to darbepoetin alfa designated JR-131. Here, we comprehensively compare the physicochemical and biological characteristics of JR-131 to darbepoetin alfa. JR-131 demonstrated similar protein structure to the originator, darbepoetin alfa, by peptide mapping and circular dichroism spectroscopy. Additionally, mass spectroscopic analyses and capillary zone electrophoresis revealed similar glycosylation patterns between the two products. Human bone marrow-derived erythroblasts differentiated and proliferated to form colonies with JR-131 to a similar degree as darbepoetin alfa. Finally, JR-131 stimulated erythropoiesis and improved anemia in rats similarly to darbepoetin alfa. Our data show the similarity in physicochemical and biological properties of JR-131 to those of darbepoetin alfa, and JR-131 therefore represents a biosimilar for use in the treatment of renal anemia.

Iduronate-2-Sulfatase with Anti-human Transferrin Receptor Antibody for Neuropathic Mucopolysaccharidosis II: A Phase 1/2 Trial.

Hunter syndrome (mucopolysaccharidosis II [MPS II]), a deficiency of iduronate-2-sulfatase (IDS), causes an accumulation of glycosaminoglycans, giving rise to multiple systemic and CNS symptoms. The currently available therapies, idursulfase and idursulfase beta, are ineffective against the CNS symptoms because they cannot pass the blood-brain barrier (BBB). A novel IDS fused with anti-human transferrin receptor antibody (JR-141) has been shown to penetrate the BBB and ameliorate learning deficits in model mice. This first-in-human study evaluated the pharmacokinetics, safety, and potential efficacy of JR-141 in 14 patients with MPS II. In a dose-escalation study performed in two patients, JR-141 plasma concentrations were dose dependent and peaked at 3 hr after initiation of each infusion, and no or only mild adverse reactions were exhibited. In a subsequent 4-week evaluation at two dose levels, the plasma concentration profiles were similar between the first and final administration, indicating no drug accumulation. Levels of heparan sulfate (HS) and dermatan sulfate (DS) were suppressed in both plasma and urine and HS levels were significantly decreased in cerebrospinal fluid. Two patients experienced some amelioration of neurocognitive and motor symptoms. These results suggest that the drug successfully penetrates the BBB and could have CNS efficacy.

Non-clinical evaluation of JR-051 as a biosimilar to agalsidase beta for the treatment of Fabry disease.

Fabry disease (FD) is an X-linked lysosomal storage disease. It is caused by deficiency of the enzyme α-galactosidase A (α-Gal A), which leads to excessive deposition of neutral glycosphingolipids, especially globotriaosylceramide (GL-3), in cells throughout the body. Progressive accumulation of GL-3 causes life-threatening complications in several tissues and organs, including the vasculature, heart, and kidney. Currently available enzyme replacement therapy for FD employs recombinant α-Gal A in two formulations, namely agalsidase alfa and agalsidase beta. Here, we evaluated JR-051 as a biosimilar to agalsidase beta in a non-clinical study. JR-051 was shown to have identical primary and similar higher-order structures to agalsidase beta. Mannose-6-phosphate content was higher in JR-051 than in agalsidase beta, which probably accounts for a slightly better uptake into fibroblasts in vitro. In spite of these differences in in vitro biological features, pharmacokinetic profiles of the two compounds in mice, rats, and monkeys were similar. The ability to reduce GL-3 accumulation in the kidney, heart, skin, liver, spleen, and plasma of Gla-knockout mice, a model of FD, was not different between JR-051 and agalsidase beta. Furthermore, we identified no safety concerns regarding JR-051 in a 13-week evaluation using cynomolgus monkeys. These findings indicate that JR-051 is similar to agalsidase beta in terms of physicochemical and biological properties.

A Blood-Brain-Barrier-Penetrating Anti-human Transferrin Receptor Antibody Fusion Protein for Neuronopathic Mucopolysaccharidosis II.

Mucopolysaccharidosis II (MPS II) is an X-linked recessive lysosomal storage disease caused by mutations in the iduronate-2-sulfatase (IDS) gene. Since IDS catalyzes the degradation of glycosaminoglycans (GAGs), deficiency in this enzyme leads to accumulation of GAGs in most cells in all tissues and organs, resulting in severe somatic and neurological disorders. Although enzyme replacement therapy with human IDS (hIDS) has been used for the treatment of MPS II, this therapy is not effective for defects in the CNS mainly because the enzyme cannot cross the blood-brain barrier (BBB). Here, we developed a BBB-penetrating fusion protein, JR-141, which consists of an anti-human transferrin receptor (hTfR) antibody and intact hIDS. The TfR-mediated incorporation of JR-141 was confirmed by using human fibroblasts in vitro. When administrated intravenously to hTfR knockin mice or monkeys, JR-141, but not naked hIDS, was detected in the brain. In addition, the intravenous administration of JR-141 reduced the accumulation of GAGs both in the peripheral tissues and in the brain of hTfR knockin mice lacking Ids, an animal model of MPS II. These data provide a proof of concept for the translation of JR-141 to clinical study for the treatment of patients with MPS II with CNS disorders.

Mesenchymal Stem Cells Overexpressing Interleukin-10 Promote Neuroprotection in Experimental Acute Ischemic Stroke.

Interleukin (IL)-10 is a contributing factor to neuroprotection of mesenchymal stem cell (MSC) transplantation after ischemic stroke. Our aim was to increase therapeutic effects by combining MSCs and ex vivo IL-10 gene transfer with an adeno-associated virus (AAV) vector using a rat transient middle cerebral artery occlusion (MCAO) model. Sprague-Dawley rats underwent 90 min MCAO followed by intravenous administration of MSCs alone or IL-10 gene-transferred MSCs (MSC/IL-10) at 0 or 3 hr after ischemia reperfusion. Infarct lesions, neurological deficits, and immunological analyses were performed within 7 days after MCAO. 0-hr transplantation of MSCs alone and MSC/IL-10 significantly reduced infarct volumes and improved motor function. Conversely, 3-hr transplantation of MSC/IL-10, but not MSCs alone, significantly reduced infarct volumes (p < 0.01) and improved motor function (p < 0.01) compared with vehicle groups at 72 hr and 7 days after MCAO. Immunological analysis showed that MSC/IL-10 transplantation significantly inhibits microglial activation and pro-inflammatory cytokine expression compared with MSCs alone. Moreover, overexpressing IL-10 suppressed neuronal degeneration and improved survival of engrafted MSCs in the ischemic hemisphere. These results suggest that overexpressing IL-10 enhances the neuroprotective effects of MSC transplantation by anti-inflammatory modulation and thereby supports neuronal survival during the acute ischemic phase.

Host Cell Proteins: The Hidden Side of Biosimilarity Assessment.

One major concern with biosimilars is that small differences compared with reference products might lead to unforeseen immunogenicity, thus affecting patient safety and drug efficacy. Differences could be due to either post-translational modifications of the therapeutic protein and/or to traces of impurities from the manufacturing process. The results presented in this communication illustrate the efforts to assess "biosimilarity" of a biosimilar candidate to a reference product for a specific group of process-related impurities, the host cell proteins (HCP). Extensive characterization of HCP in the drug substance of a biosimilar candidate revealed the identity of HCP copurifying with the protein of interest and guided process development to improve overall HCP clearance in the downstream process. The data presented illustrate the challenge of matching the reference product on either quantitative or qualitative aspects of HCP impurities.

Coformulation of a Novel Human α-Galactosidase A With the Pharmacological Chaperone AT1001 Leads to Improved Substrate Reduction in Fabry Mice.

Fabry disease is an X-linked lysosomal storage disorder caused by mutations in the gene that encodes α-galactosidase A and is characterized by pathological accumulation of globotriaosylceramide and globotriaosylsphingosine. Earlier, the authors demonstrated that oral coadministration of the pharmacological chaperone AT1001 (migalastat HCl; 1-deoxygalactonojirimycin HCl) prior to intravenous administration of enzyme replacement therapy improved the pharmacological properties of the enzyme. In this study, the authors investigated the effects of coformulating AT1001 with a proprietary recombinant human α-galactosidase A (ATB100) into a single intravenous formulation. AT1001 increased the physical stability and reduced aggregation of ATB100 at neutral pH in vitro, and increased the potency for ATB100-mediated globotriaosylceramide reduction in cultured Fabry fibroblasts. In Fabry mice, AT1001 coformulation increased the total exposure of active enzyme, and increased ATB100 levels in cardiomyocytes, cardiac vascular endothelial cells, renal distal tubular epithelial cells, and glomerular cells, cell types that do not show substantial uptake with enzyme replacement therapy alone. Notably, AT1001 coformulation also leads to greater tissue globotriaosylceramide reduction when compared with ATB100 alone, which was positively correlated with reductions in plasma globotriaosylsphingosine. Collectively, these data indicate that intravenous administration of ATB100 coformulated with AT1001 may provide an improved therapy for Fabry disease and thus warrants further investigation.

Enzyme replacement therapy (ERT) procedure for mucopolysaccharidosis type II (MPS II) by intraventricular administration (IVA) in murine MPS II.

Mucopolysaccharidosis type II (MPS II), or Hunter syndrome, is a lysosomal storage disorder caused by a deficiency of iduronate-2-sulfatase (IDS) and is characterized by the accumulation of glycosaminoglycans (GAGs). MPS II has been treated by hematopoietic stem cell therapy (HSCT)/enzyme replacement therapy (ERT), but its effectiveness in the central nervous system (CNS) is limited because of poor enzyme uptake across the blood-brain barrier (BBB). To increase the efficacy of ERT in the brain, we tested an intraventricular ERT procedure consisting of repeated administrations of IDS (20 µg/mouse/3 weeks) in IDS-knockout, MPS II model mice. The IDS enzyme activity and the accumulation of total GAGs were measured in mouse brains. The IDS activity was significantly increased, and the accumulation of total GAGs was decreased in the MPS II mouse brains treated with multiple administrations of IDS via intraventricular ERT. Additionally, a high level of IDS enzyme activity was appreciated in other MPS II mouse tissues, such as the liver, spleen, testis and others. A Y-maze was used to test learning and memory after repeated intraventricular ERT with IDS. The IDS-treated mouse groups recovered the capacity for short-term memory and activity. Although large and small vacuoles were found at the margin of the cerebellar Purkinje cells in the disease-control mice, these vacuoles disappeared upon treated with IDS. Loss of vacuoles was also observed in other tissues (liver, kidney and testis). These results demonstrate the possible efficacy of an ERT procedure with intraventricular administration of IDS for the treatment of MPS II.