Dr. O'Neill serves as a member of the Executive Board and provides consulting on many aspects of vision science with a specific focus on study design and regulatory requirement considerations for IND submission. Dr. O'Neill is an Assistant Adjunct Professor in the Pharmacology and Toxicology Graduate Group at University of California-Davis. He has contributed to 26 regulatory submissions in the US, EU, Australia and Japan, coauthored over 40 peer-reviewed publications, and been a Diplomate of the American Board of Toxicology since 1995. With 14 years of biotechnology and pharmaceutical development experience, Dr. O'Neill has led non-clinical development efforts regarding anti-angiogenic molecules including the targeted oncology monoclonal antibody AvastinTM, and the intra-vitreally delivered monoclonal antibody fragment LucentisTM, a treatment for the neovascular form of age-related macular degeneration.
Safety Findings of Dosing Gene Therapy Vectors in NHP With Pre-existing or Treatment-Emergent Anti-capsid Antibodies
Toxicol Pathol. 2023 Nov 3:1926233231202995. doi: 10.1177/01926233231202995. Online ahead of print.
Replication-incompetent adeno-associated virus (AAV)-based vectors are nonpathogenic viral particles used to deliver therapeutic genes to treat multiple monogenic disorders. AAVs can elicit immune responses; thus, one challenge in AAV-based gene therapy is the presence of neutralizing antibodies against vector capsids that may prevent transduction of target cells or elicit adverse findings. We present safety findings from two 12-week studies in nonhuman primates (NHPs) with pre-existing or treatment-emergent antibodies. In the first study, NHPs with varying levels of naturally acquired anti-AAV5 antibodies were dosed with an AAV5-based vector encoding human factor VIII (hFVIII). In the second study, NHPs with no pre-existing anti-AAV antibodies were dosed with an AAV5-based vector carrying the beta subunit of choriogonadotropic hormone (bCG); this led to the induction of high-titer antibodies against the AAV5 capsid. Four weeks later, the same NHPs received an equivalent dose of an AAV5-based vector carrying human factor IX (hFIX). In both of these studies, the administration of vectors carrying hFVIII, bCG, and hFIX was well-tolerated in NHPs with no adverse clinical pathology or microscopic findings. These two studies demonstrate the safety of AAV-based vector administration in NHPs with either low-titer pre-existing anti-AAV5 antibodies or re-administration, even in the presence of high-titer antibodies.
Safety, pharmacokinetics and CNS distribution of tralesinidase alfa administered via intracerebroventricular infusion to juvenile cynomolgus monkeys
Toxicol Rep. 2023 Mar 1;10:357-366. doi: 10.1016/j.toxrep.2023.02.014. eCollection 2023.
Mucopolysaccharidosis Type IIIB (MPS IIIB) is an ultrarare, fatal pediatric disease with no approved therapy. It is caused by mutations in the gene encoding for lysosomal enzyme alpha-N-acetylglucosaminidase (NAGLU). Tralesinidase alfa (TA) is a fusion protein comprised of recombinant NAGLU and a modified human insulin-like growth factor 2 that is being developed as an enzyme replacement therapy for MPS IIIB. Since MPS IIIB is a pediatric disease the safety/toxicity, pharmacokinetics and biodistribution of TA were evaluated in juvenile non-human primates that were administered up to 5 weekly intracerebroventricular (ICV) or single intravenous (IV) infusions of TA. TA administered by ICV slow-, ICV isovolumetric bolus- or IV-infusion was well-tolerated, and no effects were observed on clinical observations, electrocardiographic or ophthalmologic parameters, or respiratory rates. The drug-related changes observed were limited to increased cell infiltrates in the CSF and along the ICV catheter track after ICV administration. These findings were not associated with functional changes and are associated with the use of ICV catheters. The CSF PK profiles were consistent across all conditions tested and TA distributed widely in the CNS after ICV administration. Anti-drug antibodies were observed but did not appear to significantly affect the exposure to TA. Correlations between TA concentrations in plasma and brain regions in direct contact with the cisterna magna suggest glymphatic drainage may be responsible for clearance of TA from the CNS. The data support the administration of TA by isovolumetric bolus ICV infusion to pediatric patients with MPS IIIB.
Brain Alterations in Aged OVT73 Sheep Model of Huntington's Disease: An MRI Based Approach
J Huntingtons Dis. 2022;11(4):391-406. doi: 10.3233/JHD-220526.
BACKGROUND: Huntington's disease (HD) is a fatal neurodegenerative autosomal dominant disorder with prevalence of 1 : 20000 that has no effective treatment to date. Translatability of candidate therapeutics could be enhanced by additional testing in large animal models because of similarities in brain anatomy, size, and immunophysiology. These features enable realistic pre-clinical studies of biodistribution, efficacy, and toxicity.
OBJECTIVE AND METHODS: Here we non-invasively characterized alterations in brain white matter microstructure, neurochemistry, neurological status, and mutant Huntingtin protein (mHTT) levels in cerebrospinal fluid (CSF) of aged OVT73 HD sheep.
RESULTS: Similar to HD patients, CSF mHTT differentiates HD from normal sheep. Our results are indicative of a decline in neurological status, and alterations in brain white matter diffusion and spectroscopy metric that are more severe in aged female HD sheep. Longitudinal analysis of aged female HD sheep suggests that the decline is detectable over the course of a year. In line with reports of HD human studies, white matter alterations in corpus callosum correlates with a decline in gait of HD sheep. Moreover, alterations in the occipital cortex white matter correlates with a decline in clinical rating score. In addition, the marker of energy metabolism in striatum of aged HD sheep, shows a correlation with decline of clinical rating score and eye coordination.
CONCLUSION: This data suggests that OVT73 HD sheep can serve as a pre-manifest large animal model of HD providing a platform for pre-clinical testing of HD therapeutics and non-invasive tracking of the efficacy of the therapy.
Tralesinidase Alfa Enzyme Replacement Therapy Prevents Disease Manifestations in a Canine Model of Mucopolysaccharidosis Type IIIB
J Pharmacol Exp Ther. 2022 Sep;382(3):277-286. doi: 10.1124/jpet.122.001119. Epub 2022 Jun 18.
Mucopolysaccharidosis type IIIB (MPS IIIB; Sanfilippo syndrome B; OMIM #252920) is a lethal, pediatric, neuropathic, autosomal recessive, and lysosomal storage disease with no approved therapy. Patients are deficient in the activity of N-acetyl-alpha-glucosaminidase (NAGLU; EC 3.2.150), necessary for normal lysosomal degradation of the glycosaminoglycan heparan sulfate (HS). Tralesinidase alfa (TA), a fusion protein comprised of recombinant human NAGLU and a modified human insulin-like growth factor 2, is in development as an enzyme replacement therapy that is administered via intracerebroventricular (ICV) infusion, thus circumventing the blood brain barrier. Previous studies have confirmed ICV infusion results in widespread distribution of TA throughout the brains of mice and nonhuman primates. We assessed the long-term tolerability, pharmacology, and clinical efficacy of TA in a canine model of MPS IIIB over a 20-month study. Long-term administration of TA was well tolerated as compared with administration of vehicle. TA was widely distributed across brain regions, which was confirmed in a follow-up 8-week pharmacokinetic/pharmacodynamic study. MPS IIIB dogs treated for up to 20 months had near-normal levels of HS and nonreducing ends of HS in cerebrospinal fluid and central nervous system (CNS) tissues. TA-treated MPS IIIB dogs performed better on cognitive tests and had improved CNS pathology and decreased cerebellar volume loss relative to vehicle-treated MPS IIIB dogs. These findings demonstrate the ability of TA to prevent or limit the biochemical, pathologic, and cognitive manifestations of canine MPS IIIB disease, thus providing support of its potential long-term tolerability and efficacy in MPS IIIB subjects. SIGNIFICANCE STATEMENT: This work illustrates the efficacy and tolerability of tralesinidase alfa as a potential therapeutic for patients with mucopolysaccharidosis type IIIB (MPS IIIB) by documenting that administration to the central nervous system of MPS IIIB dogs prevents the accumulation of disease-associated glycosaminoglycans in lysosomes, hepatomegaly, cerebellar atrophy, and cognitive decline.
Lack of germline transmission in male mice following a single intravenous administration of AAV5-hFVIII-SQ gene therapy
Gene Ther. 2023 Aug;30(7-8):581-586. doi: 10.1038/s41434-022-00318-5. Epub 2022 Feb 7.
Valoctocogene roxaparvovec (AAV5-hFVIII-SQ) is an adeno-associated virus serotype five gene therapy under investigation for the treatment of hemophilia A. Herein, we assessed the potential for germline transmission of AAV5-hFVIII-SQ in mice. Male B6.129S6-Rag2tm1Fwa N12 mice received a single intravenous dose of vehicle or 6 × 1013 vg/kg AAV5-hFVIII-SQ. Vehicle and AAV5-hFVIII-SQ-treated mice were mated with naïve females 4 days after dosing, when the concentration of vector genomes was expected to be at its peak in semen, and 37 days after dosing, when a full spermatogenesis cycle was estimated to be complete. Quantitative PCR was used to evaluate the presence of transgene DNA in liver and testes from F0 males dosed with AAV5-hFVIII-SQ and liver tissue of F1 offspring. Transgene DNA was detected in liver and testes of all F0 males dosed with AAV5-hFVIII-SQ, confirming successful transduction. Importantly, no transgene DNA was detected in any tested F1 offspring derived from F0 males dosed with AAV5-hFVIII-SQ. Using a novel 2-stage statistical model that takes into account the number of males dosed with AAV5-hFVIII-SQ and the number of offspring sired by these males, we estimate that the risk of germline transmission is <5% with a 99.2% confidence level.
Molecular analysis of AAV5-hFVIII-SQ vector-genome-processing kinetics in transduced mouse and nonhuman primate livers
Mol Ther Methods Clin Dev. 2021 Dec 21;24:142-153. doi: 10.1016/j.omtm.2021.12.004. eCollection 2022 Mar 10.
Valoctocogene roxaparvovec (AAV5-hFVIII-SQ) is an adeno-associated virus serotype 5 (AAV5)-based gene therapy vector containing a B-domain-deleted human coagulation factor VIII (hFVIII) gene controlled by a liver-selective promoter. AAV5-hFVIII-SQ is currently under clinical investigation as a treatment for severe hemophilia A. The full-length AAV5-hFVIII-SQ is >4.9 kb, which is over the optimal packaging limit of AAV5. Following administration, the vector must undergo a number of genome-processing, assembly, and repair steps to form full-length circularized episomes that mediate long-term FVIII expression in target tissues. To understand the processing kinetics of the oversized AAV5-hFVIII-SQ vector genome into circular episomes, we characterized the various molecular forms of the AAV5-hFVIII-SQ genome at multiple time points up to 6 months postdose in the liver of murine and non-human primate models. Full-length circular episomes were detected in liver tissue beginning 1 week postdosing. Over 6 months, quantities of circular episomes (in a predominantly head-to-tail configuration) increased, while DNA species lacking inverted terminal repeats were preferentially degraded. Levels of duplex, circular, full-length genomes significantly correlated with levels of hFVIII-SQ RNA transcripts in mice and non-human primates dosed with AAV5-hFVIII-SQ. Altogether, we show that formation of full-length circular episomes in the liver following AAV5-hFVIII-SQ transduction was associated with long-term FVIII expression.
Dose selection for intracerebroventricular cerliponase alfa in children with CLN2 disease, translation from animal to human in a rare genetic disease
Clin Transl Sci. 2021 Sep;14(5):1810-1821. doi: 10.1111/cts.13028. Epub 2021 Jun 2.
Neuronal ceroid lipofuscinosis type 2 (CLN2 disease) is an ultra-rare pediatric neurodegenerative disorder characterized by deficiency of the lysosomal enzyme tripeptidyl peptidase-1 (TPP1). In the absence of adequate TPP1, lysosomal storage material accumulation occurs in the central nervous system (CNS) accompanied by neurodegeneration and neurological decline that culminates in childhood death. Cerliponase alfa is a recombinant human TPP1 enzyme replacement therapy administered via intracerebroventricular infusion and approved for the treatment of CLN2 disease. Here, we describe two allometric methods, calculated by scaling brain mass across species, that informed the human dose selection and exposure prediction of cerliponase alfa from preclinical studies in monkeys and a dog model of CLN2 disease: (1) scaling of dose using a human-equivalent dose factor; and (2) scaling of compartmental pharmacokinetic (PK) model parameters. Source PK data were obtained from cerebrospinal fluid (CSF) samples from dogs and monkeys, and the human exposure predictions were confirmed with CSF data from the first-in-human clinical study. Nonclinical and clinical data were analyzed using noncompartmental analysis and nonlinear mixed-effect modeling approaches. Both allometric methods produced CSF exposure predictions within twofold of the observed exposure parameters maximum plasma concentration (Cmax ) and area under the curve (AUC). Furthermore, cross-species qualification produced consistent and reasonable PK profile predictions, which supported the allometric scaling of model parameters. The challenges faced in orphan drug development place an increased importance on, and opportunity for, data translation from research and nonclinical development. Our approach to dose translation and human exposure prediction for cerliponase alfa may be applicable to other CNS administered therapies being developed.
Intravitreal enzyme replacement inhibits progression of retinal degeneration in canine CLN2 neuronal ceroid lipofuscinosis
Exp Eye Res. 2020 Sep;198:108135. doi: 10.1016/j.exer.2020.108135. Epub 2020 Jul 4.
CLN2 neuronal ceroid lipofuscinosis is a rare recessive hereditary retinal and neurodegenerative disease resulting from deleterious sequence variants in TPP1 that encodes the soluble lysosomal enzyme tripeptidyl peptidase-1 (TPP1). Children with this disorder develop normally, but starting at 2-4 years of age begin to exhibit neurological signs and visual deficits. Vision loss that progresses to blindness is associated with progressive retinal degeneration and impairment of retinal function. Similar progressive loss of retinal function and retinal degeneration occur in a dog CLN2 disease model with a TPP1 null sequence variant. Studies using the dog model were conducted to determine whether intravitreal injection of recombinant human TPP1 (rhTPP1) administered starting after onset of retinal functional impairment could slow or halt the progression of retinal functional decline and degeneration. TPP1-null dogs received intravitreal injections of rhTPP1 in one eye and vehicle in the other eye beginning at 23.5-25 weeks of age followed by second injections at 34-40 weeks in 3 out of 4 dogs. Ophthalmic exams, in vivo ocular imaging, and electroretinography (ERG) were repeated regularly to monitor retinal structure and function. Retinal histology was evaluated in eyes collected from these dogs when they were euthanized at end-stage neurological disease (40-45 weeks of age). Intravitreal rhTPP1 injections were effective in preserving retinal function (as measured with the electroretinogram) and retinal morphology for as long as 4 months after a single treatment. These findings indicate that intravitreal injection of rhTPP1 administered after partial loss of retinal function is an effective treatment for preserving retinal structure and function in canine CLN2 disease.
Intravitreal enzyme replacement preserves retinal structure and function in canine CLN2 neuronal ceroid lipofuscinosis
Exp Eye Res. 2020 Aug;197:108130. doi: 10.1016/j.exer.2020.108130. Epub 2020 Jul 1.
CLN2 neuronal ceroid lipofuscinosis is a hereditary neurodegenerative disorder characterized by progressive vision loss, neurological decline, and seizures. CLN2 disease results from mutations in TPP1 that encodes the lysosomal enzyme tripeptidyl peptidase-1 (TPP1). Children with CLN2 neuronal ceroid lipofuscinosis experience ocular disease, characterized by progressive retinal degeneration associated with impaired retinal function and gradual vision loss culminating in total blindness. A similar progressive loss of retinal function is also observed in a dog CLN2 model with a TPP1 null mutation. A study was conducted to evaluate the efficacy of periodic intravitreal injections of recombinant human (rh) TPP1 in inhibiting retinal degeneration and preserving retinal function in the canine model. TPP1 null dogs received periodic intravitreal injections of rhTPP1 in one eye and vehicle in the other eye beginning at approximately 12 weeks of age. Ophthalmic exams, in vivo ocular imaging, and electroretinography (ERG) were repeated regularly to monitor retinal structure and function. Retinal histology was evaluated in eyes collected from these dogs when they were euthanized at end-stage neurological disease (43-46 weeks of age). Intravitreal rhTPP1 dosing prevented disease-related declines in ERG amplitudes in the TPP1-treated eyes. At end-stage neurologic disease, TPP1-treated eyes retained normal morphology while the contralateral vehicle-treated eyes exhibited loss of inner retinal neurons and photoreceptor disorganization typical of CLN2 disease. The treatment also prevented the development of disease-related focal retinal detachments observed in the control eyes. Uveitis occurred secondary to the administration of the rhTPP1 but did not hinder the therapeutic benefits. These findings demonstrate that periodic intravitreal injection of rhTPP1 preserves retinal structure and function in canine CLN2 disease.
Translational studies of intravenous and intracerebroventricular routes of administration for CNS cellular biodistribution for BMN 250, an enzyme replacement therapy for the treatment of Sanfilippo type B
Drug Deliv Transl Res. 2020 Apr;10(2):425-439. doi: 10.1007/s13346-019-00683-6.
BMN 250 is being developed as enzyme replacement therapy for Sanfilippo type B, a primarily neurological rare disease, in which patients have deficient lysosomal alpha-N-acetylglucosaminidase (NAGLU) enzyme activity. BMN 250 is taken up in target cells by the cation-independent mannose 6-phosphate receptor (CI-MPR, insulin-like growth factor 2 receptor), which then facilitates transit to the lysosome. BMN 250 is dosed directly into the central nervous system via the intracerebroventricular (ICV) route, and the objective of this work was to compare systemic intravenous (IV) and ICV delivery of BMN 250 to confirm the value of ICV dosing. We first assess the ability of enzyme to cross a potentially compromised blood-brain barrier in the Naglu-/- mouse model and then assess the potential for CI-MPR to be employed for receptor-mediated transport across the blood-brain barrier. In wild-type and Naglu-/- mice, CI-MPR expression in brain vasculature is high during the neonatal period but virtually absent by adolescence. In contrast, CI-MPR remains expressed through adolescence in non-affected non-human primate and human brain vasculature. Combined results from IV administration of BMN 250 in Naglu-/- mice and IV and ICV administration in healthy juvenile non-human primates suggest a limitation to therapeutic benefit from IV administration because enzyme distribution is restricted to brain vascular endothelial cells: enzyme does not reach target neuronal cells following IV administration, and pharmacological response following IV administration is likely restricted to clearance of substrate in endothelial cells. In contrast, ICV administration enables central nervous system enzyme replacement with biodistribution to target cells.
The Impact of Pre-existing Immunity on the Non-clinical Pharmacodynamics of AAV5-Based Gene Therapy
Mol Ther Methods Clin Dev. 2019 Apr 11;13:440-452. doi: 10.1016/j.omtm.2019.03.006. eCollection 2019 Jun 14.
Adeno-associated virus (AAV)-based vectors are widely used for gene therapy, but the effect of pre-existing antibodies resulting from exposure to wild-type AAV is unclear. In addition, other poorly defined plasma factors could inhibit AAV vector transduction where antibodies are not detected. To better define the relationship between various forms of pre-existing AAV immunity and gene transfer, we studied valoctocogene roxaparvovec (BMN 270) in cynomolgus monkeys with varying pre-dose levels of neutralizing anti-AAV antibodies and non-antibody transduction inhibitors. BMN 270 is an AAV5-based vector for treating hemophilia A that encodes human B domain-deleted factor VIII (FVIII-SQ). After infusion of BMN 270 (6.0 × 1013 vg/kg) into animals with pre-existing anti-AAV5 antibodies, there was a mean decrease in maximal FVIII-SQ plasma concentration (Cmax) and AUC of 74.8% and 66.9%, respectively, compared with non-immune control animals, and vector genomes in the liver were reduced. In contrast, animals with only non-antibody transduction inhibitors showed FVIII-SQ plasma concentrations and liver vector copies comparable with those of controls. These results demonstrate that animals without AAV5 antibodies are likely responders to AAV5 gene therapy, regardless of other inhibiting plasma factors. The biological threshold for tolerable AAV5 antibody levels varied between individual animals and should be evaluated further in clinical studies.
<em>Ex Vivo</em> Gene Therapy: Graft-versus-host Disease (GVHD) in NSG™ (NOD.Cg-Prkdc<sup>scid</sup> Il2rg<sup>tm1Wjl</sup>/SzJ) Mice Transplanted with CD34<sup>+</sup> Human Hematopoietic Stem Cells
Toxicol Pathol. 2019 Jul;47(5):656-660. doi: 10.1177/0192623319844484. Epub 2019 May 7.
A therapeutic option for monogenic disorders is gene therapy with ex vivo-transduced autologous hematopoietic stem cells (HSCs). Safety or efficacy studies of ex vivo-modified HSCs are conducted in humanized mouse models after ablation of the murine bone marrow and transfer of human CD34+ HSCs. Engrafted human CD34+ cells migrate to bone marrow and differentiate into various human hematopoietic lineages. A 12-week study was conducted in NSG™ mice to evaluate engraftment, differentiation, and safety of human CD34+ cells that were transduced (ex vivo) with a proprietary lentiviral vector encoding a human gene (BMRN-1) or a mock (green fluorescent protein) vector. Several mice intravenously injected with naive CD34+ cells or transduced CD34+ cells had variable lymphohistiocytic inflammatory cell infiltrates and microgranulomas in the liver and lungs consistent with graft-versus-host disease (GVHD). Spleen, bone marrow, stomach, reproductive tract, but not the skin had similar inflammatory changes. Ex vivo viral transduction of CD34+ cells did not impact engraftment or predispose to xenogeneic GVHD.
Immunogenicity to cerliponase alfa intracerebroventricular enzyme replacement therapy for CLN2 disease: Results from a Phase 1/2 study
Clin Immunol. 2018 Dec;197:68-76. doi: 10.1016/j.clim.2018.09.003. Epub 2018 Sep 8.
Treatment with intracerebroventricular (ICV)-delivered cerliponase alfa enzyme replacement therapy (ERT) in a Phase 1/2 study of 24 subjects with CLN2 disease resulted in a meaningful preservation of motor and language (ML) function and was well tolerated. Treatment was associated with anti-drug antibody (ADA) production in the cerebrospinal fluid (CSF) of 6/24 (25%) and in the serum of 19/24 (79%) of clinical trial subjects, respectively, over a mean exposure of 96.4 weeks (range 0.1-129 weeks). Neutralizing antibodies (NAb) were not detected in the CSF of any of the subjects. No events of anaphylaxis were reported. Neither the presence of serum ADA nor drug-specific immunoglobulin E was associated with the incidence or severity of hypersensitivity adverse events. Serum and CSF ADA titers did not correlate with change in ML score. Therefore, the development of an ADA response to cerliponase alfa is not predictive of an adverse safety profile or poor treatment outcome.
Gene Therapy with BMN 270 Results in Therapeutic Levels of FVIII in Mice and Primates and Normalization of Bleeding in Hemophilic Mice
Mol Ther. 2018 Feb 7;26(2):496-509. doi: 10.1016/j.ymthe.2017.12.009. Epub 2017 Dec 14.
Hemophilia A is an X-linked bleeding disorder caused by mutations in the gene encoding the factor VIII (FVIII) coagulation protein. Bleeding episodes in patients are reduced by prophylactic therapy or treated acutely using recombinant or plasma-derived FVIII. We have made an adeno-associated virus 5 vector containing a B domain-deleted (BDD) FVIII gene (BMN 270) with a liver-specific promoter. BMN 270 injected into hemophilic mice resulted in a dose-dependent expression of BDD FVIII protein and a corresponding correction of bleeding time and blood loss. At the highest dose tested, complete correction was achieved. Similar corrections in bleeding were observed at approximately the same plasma levels of FVIII protein produced either endogenously by BMN 270 or following exogenous administration of recombinant BDD FVIII. No evidence of liver dysfunction or hepatocyte endoplasmic reticulum stress was observed. Comparable doses in primates produced similar levels of circulating FVIII. These preclinical data support evaluation of BMN 270 in hemophilia A patients.
Maternal phenylketonuria syndrome: studies in mice suggest a potential approach to a continuing problem
Pediatr Res. 2018 Apr;83(4):889-896. doi: 10.1038/pr.2017.323. Epub 2018 Jan 31.
BackgroundUntreated phenylketonuria (PKU), one of the most common human genetic disorders, usually results in mental retardation. Although a protein-restricted artificial diet can prevent retardation, dietary compliance in adults is often poor. In pregnant PKU women, noncompliance can result in maternal PKU syndrome, where high phenylalanine (Phe) levels cause severe fetal complications. Enzyme substitution therapy using Phe ammonia lyase (PAL) corrects PKU in BTBR Phe hydroxylase (Pahenu2) mutant mice, suggesting a potential for maternal PKU syndrome treatment in humans.MethodsWe reviewed clinical data to assess maternal PKU syndrome incidence in pregnant PKU women. We treated female PKU mice (on normal diet) with PAL, stabilizing Phe at physiological levels, and mated them to assess pregnancy outcomes.ResultsPatient records show that, unfortunately, the efficacy of diet to prevent maternal PKU syndrome has not significantly improved since the problem was first noted 40 years ago. PAL treatment of pregnant PKU mice shows that offspring of PAL-treated dams survive to adulthood, in contrast to the complete lethality seen in untreated mice, or limited survival seen in mice on a PKU diet.ConclusionPAL treatment reduced maternal PKU syndrome severity in mice and may have potential for human PKU therapy.
Partial rescue of neuropathology in the murine model of PKU following administration of recombinant phenylalanine ammonia lyase (pegvaliase)
Mol Genet Metab. 2017 Sep;122(1-2):33-35. doi: 10.1016/j.ymgme.2017.04.013. Epub 2017 Apr 29.
Pegylated recombinant phenylalanine ammonia lyase (pegvaliase) is an enzyme substitution therapy being evaluated for the treatment of phenylketonuria (PKU). PKU is characterized by elevated plasma phenylalanine, which is thought to lead to a deficiency in monoamine neurotransmitters and ultimately, neurocognitive dysfunction. A natural history evaluation in a mouse model of PKU demonstrated a profound decrease in tyrosine hydroxylase (TH) immunoreactivity in several brain regions, beginning at 4weeks of age. Following treatment with pegvaliase, the number of TH positive neurons was increased in several brain regions compared to placebo treated ENU2 mice.
Long-term Immunogenicity of Elosulfase Alfa in the Treatment of Morquio A Syndrome: Results From MOR-005, a Phase III Extension Study
Clin Ther. 2017 Jan;39(1):118-129.e3. doi: 10.1016/j.clinthera.2016.11.017. Epub 2016 Dec 10.
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.
Reveglucosidase alfa (BMN 701), an IGF2-Tagged rhAcid α-Glucosidase, Improves Respiratory Functional Parameters in a Murine Model of Pompe Disease
J Pharmacol Exp Ther. 2017 Feb;360(2):313-323. doi: 10.1124/jpet.116.235952. Epub 2016 Nov 16.
Pompe disease is a rare neuromuscular disorder caused by an acid α-glucosidase (GAA) deficiency resulting in glycogen accumulation in muscle, leading to myopathy and respiratory weakness. Reveglucosidase alfa (BMN 701) is an insulin-like growth factor 2-tagged recombinant human acid GAA (rhGAA) that enhances rhGAA cellular uptake via a glycosylation-independent insulin-like growth factor 2 binding region of the cation-independent mannose-6-phosphate receptor (CI-MPR). The studies presented here evaluated the effects of Reveglucosidase alfa treatment on glycogen clearance in muscle relative to rhGAA, as well as changes in respiratory function and glycogen clearance in respiratory-related tissue in a Pompe mouse model (GAAtm1Rabn/J). In a comparison of glycogen clearance in muscle with Reveglucosidase alfa and rhGAA, Reveglucosidase alfa was more effective than rhGAA with 2.8-4.7 lower EC50 values, probably owing to increased cellular uptake. The effect of weekly intravenous administration of Reveglucosidase alfa on respiratory function was monitored in Pompe and wild-type mice using whole body plethysmography. Over 12 weeks of 20-mg/kg Reveglucosidase alfa treatment in Pompe mice, peak inspiratory flow (PIF) and peak expiratory flow (PEF) stabilized with no compensation in respiratory rate and inspiratory time during hypercapnic and recovery conditions compared with vehicle-treated Pompe mice. Dose-related decreases in glycogen levels in both ambulatory and respiratory muscles generally correlated to changes in respiratory function. Improvement of murine PIF and PEF were similar in magnitude to increases in maximal inspiratory and expiratory pressure observed clinically in late onset Pompe patients treated with Reveglucosidase alfa (Byrne et al., manuscript in preparation).
Antibodies that neutralize cellular uptake of elosulfase alfa are not associated with reduced efficacy or pharmacodynamic effect in individuals with Morquio A syndrome
J Immunol Methods. 2017 Jan;440:41-51. doi: 10.1016/j.jim.2016.10.006. Epub 2016 Oct 24.
Many enzyme replacement therapies (ERTs) for lysosomal storage disorders use the cell-surface cation-independent mannose-6 phosphate receptor (CI-M6PR) to deliver ERTs to the lysosome. However, neutralizing antibodies (NAb) may interfere with this process. We previously reported that most individuals with Morquio A who received elosulfase alfa in the phase 3 MOR-004 trial tested positive for NAbs capable of interfering with binding to CI-M6PR ectodomain in an ELISA-based assay. However, no correlation was detected between NAb occurrence and clinical efficacy or pharmacodynamics. To quantify and better characterize the impact of NAbs, we developed a functional cell-based flow cytometry assay with a titer step that detects antibodies capable of interfering with elosulfase alfa uptake. Serum samples collected during the MOR-004 trial were tested and titers were determined. Consistent with earlier findings on NAb positivity, no correlations were observed between NAb titers and the clinical outcomes of elosulfase alfa-treated individuals with Morquio A.
Workshop Proceedings: Streamlined Development of Safety Assessment Programs Supporting Orphan/Rare Diseases-Are We There Yet?
Int J Toxicol. 2016 Jul;35(4):393-409. doi: 10.1177/1091581816644709. Epub 2016 Jun 6.
A workshop entitled "Streamlined Development of Safety Assessment Programs Supporting Orphan/Rare Diseases-Are We There Yet?" was held at the 36th Annual Meeting of the American College of Toxicology in Summerlin, Nevada. The workshop was sponsored by Shire and Ultragenyx and was designed to present the nonclinical considerations for the development of various products for rare diseases. A panel of experts from industry and government highlighted the nonclinical considerations in developing toxicology programs supporting rare disease therapeutics, challenges in preclinical safety assessment, reviewed the current guidance, and presented the progress that has been made to date. The main learning from the workshop was that nonclinical testing of therapeutics targeting rare disease warrants special considerations, and early collaboration between sponsors and health authorities may help optimize the scope and timing of the supportive studies. Specific examples for nonclinical development programs for enzyme replacement therapy (ERT) were presented. Although the symposium focused on ERTs, the concepts are broadly applicable.
Pharmacodynamics, pharmacokinetics and biodistribution of recombinant human N-acetylgalactosamine 4-sulfatase after 6months of therapy in cats using different IV infusion durations
Mol Genet Metab. 2016 Feb;117(2):157-63. doi: 10.1016/j.ymgme.2015.10.006. Epub 2015 Oct 21.
BACKGROUND: Mucopolysaccharidosis VI (MPS VI) is a lysosomal storage disease characterized by an absence or marked reduction of lysosomal N-acetylgalactosamine-4-sulfatase activity. Affected individuals have widespread accumulation of unmetabolized glycosaminoglycan substrates leading to detrimental effects. Recombinant human N-acetylgalactosamine 4-sulfatase (rhASB) is an approved enzyme replacement therapy for patients with MPS VI. Despite the known efficacy of weekly 4-h rhASB infusions, some clinicians wish to treat patients using reduced infusion times. This study compared the pharmacodynamics, pharmacokinetics, and tissue biodistribution of rhASB when administered as 2- and 4-h intravenous infusions using a feline model of MPS VI.
METHODS: Study animals were MPS VI-affected cats that demonstrate clinical signs and biochemical derangements similar to human MPS VI patients. Beginning at age 4weeks, animals received weekly 2-h (N=6) or 4-h (N=6) IV infusions of rhASB for 26weeks (Naglazyme® [galsulfase] Solution for Intravenous Infusion; BioMarin Pharmaceutical, Inc.). The control group consisted of untreated MPS VI-affected cats (N=6). The pharmacokinetic parameters of plasma rhASB and urinary glycosaminoglycan were determined at weeks 13 and 26. Animals were euthanized 48h after the last infusion and tissue concentration of ASB, GAG and β-glucuronidase were measured in the liver, spleen, aorta, and kidney. Skeletal and ophthalmological evaluations were performed within 2weeks of euthanasia.
RESULTS: At week 13, the mean AUC0-t in animals treated with 4-h infusions was similar to 2-h infusions while the Cmax of the 4-h infusion was 50% of the 2-h infusion. By week 26, the mean AUC0-t of the 4-h infusion was 1.3-fold higher than the 2-h infusion (p<0.05) while Cmax of the 4-h infusion was 70% of the 2-h infusion (p<0.05). Among animals treated with 2- and 4-h infusions, there was no difference in urinary GAG excretion, tissue GAG storage, tissue galsulfase activity, and β-glucuronidase but all were significantly different than control animals (for each, p<0.001). Radiographic skeletal abnormality scores for animals were also similar for both treatment groups and significantly higher than control animals (p<0.001). There was no significant difference in corneal clouding scores among treated and untreated animals.
CONCLUSIONS: There was no significant difference in clinical outcomes when rhASB was administered to MPS VI affected cats as 2- and 4-h infusions over 26weeks. Additional studies may determine if shorter infusion times are appropriate for MPS VI patients without significant infusion-associated reactions.
Effects of Food Intake on the Relative Bioavailability of Amifampridine Phosphate Salt in Healthy Adults
Clin Ther. 2015 Jul 1;37(7):1555-63. doi: 10.1016/j.clinthera.2015.05.498. Epub 2015 Jun 20.
PURPOSE: Amifampridine (3,4-diaminopyridine) has been approved in the European Union for the treatment of Lambert-Eaton myasthenic syndrome. Amifampridine has a narrow therapeutic index, and supratherapeutic exposure has been associated with dose-dependent adverse events, including an increased risk for seizure. This study assessed the effect of food on the relative bioavailability of amifampridine in healthy subjects and informed on conditions that can alter exposure.
METHODS: This randomized, open-labeled, 2-treatment, 2-period crossover study enrolled 47 healthy male and female subjects. Subjects were randomly assigned to receive 2 single oral doses of amifampridine phosphate salt (20 mg base equivalents per dose) under fed or fasted conditions separated by a washout period. Blood and urine samples for pharmacokinetic analyses were taken before and after dosing. Plasma concentrations of amifampridine and an inactive 3-N-acetyl metabolite were determined. The relative bioavailability values of amifampridine and metabolite were assessed based on the plasma PK parameters AUC0-∞, AUC0-t, and Cmax in the fed and fasted states using noncompartmental pharmacokinetic analysis. Parent drug and metabolite excretion were calculated from urinary concentrations. A food effect on bioavailability would be established if the 90% CI of the ratio of population geometric mean value of AUC0-∞, AUC0-t, or Cmax between fed and fasted administration was not within the bioequivalence range of 80% to 125%. Tolerability was assessed based on adverse-event reporting, clinical laboratory assessments, physical examination including vital sign measurements, 12-lead ECG, and concurrent medication use.
FINDINGS: Food slowed and somewhat decreased the absorption of amifampridine. There was a decrease in exposure (Cmax, 44%; AUC, 20%) after oral administration of amifampridine phosphate salt in the presence of food, and mean Tmax was 2-fold longer in the fed state. The extent of exposure and plasma elimination half-life of the major metabolite was greater than those of amifampridine in the fed and fasted conditions. Mean AUCs in the fed and fasted states were slightly greater in women than men, with no difference in mean Cmax. Orally administered amifampridine was renally eliminated (>93%) as the parent compound and metabolite within 24 hours. Single oral doses of 20 mg of amifampridine phosphate salt were considered well tolerated in both the fed and fasted conditions. High intersubject variability (%CVs, >30%) in amifampridine pharmacokinetic parameter values was observed.
IMPLICATIONS: At the intended dose under fasting conditions, amifampridine exposure may be increased. European Union Drug Regulating Authorities Clinical Trials identifier: 2011-000596-13.
Genetic variation in aryl N-acetyltransferase results in significant differences in the pharmacokinetic and safety profiles of amifampridine (3,4-diaminopyridine) phosphate
Pharmacol Res Perspect. 2015 Feb;3(1):e00099. doi: 10.1002/prp2.99. Epub 2014 Dec 9.
The clinical use of amifampridine phosphate for neuromuscular junction disorders is increasing. The metabolism of amifampridine occurs via polymorphic aryl N-acetyltransferase (NAT), yet its pharmacokinetic (PK) and safety profiles, as influenced by this enzyme system, have not been investigated. The objective of this study was to assess the effect of NAT phenotype and genotype on the PK and safety profiles of amifampridine in healthy volunteers (N = 26). A caffeine challenge test and NAT2 genotyping were used to delineate subjects into slow and fast acetylators for PK and tolerability assessment of single, escalating doses of amifampridine (up to 30 mg) and in multiple daily doses (20 mg QID) of amifampridine. The results showed that fast acetylator phenotypes displayed significantly lower C max, AUC, and shorter t 1/2 for amifampridine than slow acetylators. Plasma concentrations of the N-acetyl metabolite were approximately twofold higher in fast acetylators. Gender differences were not observed. Single doses of amifampridine demonstrated dose linear PKs. Amifampridine achieved steady state plasma levels within 1 day of dosing four times daily. No accumulation or time-dependent changes in amifampridine PK parameters occurred. Overall, slow acetylators reported 73 drug-related treatment-emergent adverse events versus 6 in fast acetylators. Variations in polymorphic NAT corresponding with fast and slow acetylator phenotypes significantly affects the PK and safety profiles of amifampridine.
Neutral endopeptidase-resistant C-type natriuretic peptide variant represents a new therapeutic approach for treatment of fibroblast growth factor receptor 3-related dwarfism
J Pharmacol Exp Ther. 2015 Apr;353(1):132-49. doi: 10.1124/jpet.114.218560. Epub 2015 Feb 3.
Achondroplasia (ACH), the most common form of human dwarfism, is caused by an activating autosomal dominant mutation in the fibroblast growth factor receptor-3 gene. Genetic overexpression of C-type natriuretic peptide (CNP), a positive regulator of endochondral bone growth, prevents dwarfism in mouse models of ACH. However, administration of exogenous CNP is compromised by its rapid clearance in vivo through receptor-mediated and proteolytic pathways. Using in vitro approaches, we developed modified variants of human CNP, resistant to proteolytic degradation by neutral endopeptidase, that retain the ability to stimulate signaling downstream of the CNP receptor, natriuretic peptide receptor B. The variants tested in vivo demonstrated significantly longer serum half-lives than native CNP. Subcutaneous administration of one of these CNP variants (BMN 111) resulted in correction of the dwarfism phenotype in a mouse model of ACH and overgrowth of the axial and appendicular skeletons in wild-type mice without observable changes in trabecular and cortical bone architecture. Moreover, significant growth plate widening that translated into accelerated bone growth, at hemodynamically tolerable doses, was observed in juvenile cynomolgus monkeys that had received daily subcutaneous administrations of BMN 111. BMN 111 was well tolerated and represents a promising new approach for treatment of patients with ACH.
Immunogenicity of Elosulfase Alfa, an Enzyme Replacement Therapy in Patients With Morquio A Syndrome: Results From MOR-004, a Phase III Trial
Clin Ther. 2015 May 1;37(5):1012-1021.e6. doi: 10.1016/j.clinthera.2014.11.005. Epub 2014 Dec 6.
PURPOSE: Morquio A syndrome (mucopolysaccharidosis IVA [MPS IVA]) is a lysosomal storage disorder caused by deficiency of the enzyme N-acetylgalactosamine-6-sulfatase, which is required to degrade the glycosaminoglycan keratan sulfate. Morquio A is associated with extensive morbidity and early mortality. Elosulfase alfa is an enzyme replacement therapy that provides a treatment option for patients with Morquio A. We examined the immunogenicity profile of elosulfase alfa, assessing any correlations between antidrug antibodies and the efficacy and safety outcomes in 176 patients with Morquio A from a 24-week international Phase III trial.
METHODS: Patients were randomized to placebo (n = 59) or elosulfase alfa 2.0 mg/kg administered weekly (n = 58) or every other week (n = 59) as an ~4-hour infusion. Blood samples were routinely tested to determine drug-specific total antibody titer and neutralizing antibody (NAb) positivity. Drug-specific immunoglobulin E positivity was tested routinely and in response to severe hypersensitivity adverse events (AEs). Antidrug antibody positivity and titer were compared with efficacy and safety metrics to assess possible correlations.
FINDINGS: The 176 patients in the trial were 54% female, with a mean age of 11.9 years. In all patients treated with elosulfase alfa antidrug antibodies developed, and in the majority, antibodies capable of interfering with cation-independent mannose-6-phosphate receptor binding in vitro (NAb) developed. Less than 10% of patients tested positive for drug-specific IgE during the study. Despite the high incidence of anti-elosulfase alfa antibodies, no correlations were detected between higher total antibody titers or NAb positivity and worsened 6-minute walk test results, urine keratin sulfate levels, or hypersensitivity AEs. Drug-specific IgE positivity had no apparent association with the occurrence of anaphylaxis, other hypersensitivity AEs, and/or treatment withdrawal.
IMPLICATIONS: Despite the universal development of antidrug antibodies, elosulfase alfa treatment was both safe and well tolerated and immunogenicity was not associated with reduced treatment effect. ClinicalTrials.gov identifier: NCT01275066. (Clin Ther.
Nonclinical evaluation of CNS-administered TPP1 enzyme replacement in canine CLN2 neuronal ceroid lipofuscinosis
Mol Genet Metab. 2015 Feb;114(2):281-93. doi: 10.1016/j.ymgme.2014.09.004. Epub 2014 Sep 16.
The CLN2 form of neuronal ceroid lipofuscinosis, a type of Batten disease, is a lysosomal storage disorder caused by a deficiency of the enzyme tripeptidyl peptidase-1 (TPP1). Patients exhibit progressive neurodegeneration and loss of motor, cognitive, and visual functions, leading to death by the early teenage years. TPP1-null Dachshunds recapitulate human CLN2 disease. To characterize the safety and pharmacology of recombinant human (rh) TPP1 administration to the cerebrospinal fluid (CSF) as a potential enzyme replacement therapy (ERT) for CLN2 disease, TPP1-null and wild-type (WT) Dachshunds were given repeated intracerebroventricular (ICV) infusions and the pharmacokinetic (PK) profile, central nervous system (CNS) distribution, and safety were evaluated. TPP1-null animals and WT controls received 4 or 16mg of rhTPP1 or artificial cerebrospinal fluid (aCSF) vehicle every other week. Elevated CSF TPP1 concentrations were observed for 2-3 days after the first ICV infusion and were approximately 1000-fold higher than plasma levels at the same time points. Anti-rhTPP1 antibodies were detected in CSF and plasma after repeat rhTPP1 administration, with titers generally higher in TPP1-null than in WT animals. Widespread brain distribution of rhTPP1 was observed after chronic administration. Expected histological changes were present due to the CNS delivery catheters and were similar in rhTPP1 and vehicle-treated animals, regardless of genotype. Neuropathological evaluation demonstrated the clearance of lysosomal storage, preservation of neuronal morphology, and reduction in brain inflammation with treatment. This study demonstrates the favorable safety and pharmacology profile of rhTPP1 ERT administered directly to the CNS and supports clinical evaluation in patients with CLN2 disease.
Pharmacokinetic and pharmacodynamic evaluation of elosulfase alfa, an enzyme replacement therapy in patients with Morquio A syndrome
Clin Pharmacokinet. 2014 Dec;53(12):1137-47. doi: 10.1007/s40262-014-0173-y.
BACKGROUND AND OBJECTIVES: Morquio A syndrome (mucopolysaccharidosis IVA; MPS IVA) is a lysosomal storage disorder caused by deficiency of N-acetylgalactosamine-6-sulfatase, an enzyme required for degradation of the glycosaminoglycan keratan sulfate. Enzyme replacement therapy with elosulfase alfa provides a potential therapy for Morquio A syndrome. We analyzed the pharmacokinetics and pharmacodynamics of elosulfase alfa in Morquio A patients from a phase III clinical trial.
METHODS: In a randomized double-blind study, elosulfase alfa at 2.0 mg/kg was administrated weekly or every other week for 24 weeks. Pharmacokinetic parameters of elosulfase alfa were determined at weeks 0 and 22 by non-compartmental analysis. Safety was assessed throughout the study. The relationship of pharmacokinetic parameters to patient demographics, pharmacodynamic assessments, immunogenicity, and efficacy and safety outcomes were assessed graphically by treatment group.
RESULTS: Elosulfase alfa exposure and half-life (t(½)) increased for both dose regimens during the study. There appeared to be no consistent trend between drug clearance (CL) and patient's sex, race, body weight, or age. All patients developed anti-drug antibodies, but no association was noted between total antibody titer and CL. In contrast, positive neutralizing antibody (NAb) status appeared to associate with decreased CL and prolonged t(½) for patients in the cohort dosed weekly. NAb may interfere with receptor-mediated cellular uptake and lead to increased circulation time of elosulfase alfa.
CONCLUSION: Despite the association between NAb and decreased drug clearance, neither dosing cohort showed associations between drug exposure and change in urinary keratan sulfate, 6-min walk test distances, or the occurrence of adverse events.
Enzyme replacement therapy delays pupillary light reflex deficits in a canine model of late infantile neuronal ceroid lipofuscinosis
Exp Eye Res. 2014 Aug;125:164-72. doi: 10.1016/j.exer.2014.06.008. Epub 2014 Jun 19.
Late-infantile neuronal ceroid lipofuscinosis (CLN2 disease) is a hereditary neurological disorder characterized by progressive retinal degeneration and vision loss, cognitive and motor decline, seizures, and pronounced brain atrophy. This fatal pediatric disease is caused by mutations in the CLN2 gene which encodes the lysosomal enzyme tripeptidyl peptidase-1 (TPP1). Utilizing a TPP1-/- Dachshund model of CLN2 disease, studies were conducted to assess the effects of TPP1 enzyme replacement administered directly to the CNS on disease progression. Recombinant human TPP1 (rhTPP1) or artificial cerebrospinal fluid vehicle was administered to CLN2-affected dogs via infusion into the CSF. Untreated and vehicle treated affected dogs exhibited progressive declines in pupillary light reflexes (PLRs) and electroretinographic (ERG) responses to light stimuli. Studies were undertaken to determine whether CSF administration of rhTPP1 alters progression of the PLR and ERG deficits in the canine model. rhTPP1 administration did not inhibit the decline in ERG responses, as rhTPP1 treated, vehicle treated, and untreated dogs all exhibited similar progressive and profound declines in ERG amplitudes. However, in some of the dogs treated with rhTPP1 there were substantial delays in the appearance and progression of PLR deficits compared with untreated or vehicle treated affected dogs. These findings indicate that CSF administration of TPP1 can attenuate functional impairment of neural pathways involved in mediating the PLR but does not prevent loss of retinal responses detectable with ERG.
Enzyme replacement therapy attenuates disease progression in a canine model of late-infantile neuronal ceroid lipofuscinosis (CLN2 disease)
J Neurosci Res. 2014 Nov;92(11):1591-8. doi: 10.1002/jnr.23423. Epub 2014 Jun 17.
Using a canine model of classical late-infantile neuronal ceroid lipofuscinosis (CLN2 disease), a study was conducted to evaluate the potential pharmacological activity of recombinant human tripeptidyl peptidase-1 (rhTPP1) enzyme replacement therapy administered directly to the cerebrospinal fluid (CSF). CLN2 disease is a hereditary neurodegenerative disorder resulting from mutations in CLN2, which encodes the soluble lysosomal enzyme tripeptidyl peptidase-1 (TPP1). Infants with mutations in both CLN2 alleles develop normally but in the late-infantile/early-childhood period undergo progressive neurological decline accompanied by pronounced brain atrophy. The disorder, a form of Batten disease, is uniformly fatal, with clinical signs starting between 2 and 4 years of age and death usually occurring by the early teenage years. Dachshunds homozygous for a null mutation in the canine ortholog of CLN2 (TPP1) exhibit a similar disorder that progresses to end stage at 10.5-11 months of age. Administration of rhTPP1 via infusion into the CSF every other week, starting at approximately 2.5 months of age, resulted in dose-dependent significant delays in disease progression, as measured by delayed onset of neurologic deficits, improved performance on a cognitive function test, reduced brain atrophy, and increased life span. Based on these findings, a clinical study evaluating the potential therapeutic value of rhTPP1 administration into the CSF of children with CLN2 disease has been initiated.
Recombinant human tripeptidyl peptidase-1 infusion to the monkey CNS: safety, pharmacokinetics, and distribution
Toxicol Appl Pharmacol. 2014 May 15;277(1):49-57. doi: 10.1016/j.taap.2014.03.005. Epub 2014 Mar 15.
CLN2 disease is caused by deficiency in tripeptidyl peptidase-1 (TPP1), leading to neurodegeneration and death. The safety, pharmacokinetics (PK), and CNS distribution of recombinant human TPP1 (rhTPP1) were characterized following a single intracerebroventricular (ICV) or intrathecal-lumbar (IT-L) infusion to cynomolgus monkeys. Animals received 0, 5, 14, or 20mg rhTPP1, ICV, or 14 mg IT-L, in artificial cerebrospinal fluid (aCSF) vehicle. Plasma and CSF were collected for PK analysis. Necropsies occurred at 3, 7, and 14 days post-infusion. CNS tissues were sampled for rhTPP1 distribution. TPP1 infusion was well tolerated and without effect on clinical observations or ECG. A mild increase in CSF white blood cells (WBCs) was detected transiently after ICV infusion. Isolated histological changes related to catheter placement and infusion were observed in ICV treated animals, including vehicle controls. The CSF and plasma exposure profiles were equivalent between animals that received an ICV or IT-L infusion. TPP1 levels peaked at the end of infusion, at which point the enzyme was present in plasma at 0.3% to 0.5% of CSF levels. TPP1 was detected in brain tissues with half-lives of 3-14 days. CNS distribution between ICV and IT-L administration was similar, although ICV resulted in distribution to deep brain structures including the thalamus, midbrain, and striatum. Direct CNS infusion of rhTPP1 was well tolerated with no drug related safety findings. The favorable nonclinical profile of ICV rhTPP1 supports the treatment of CLN2 by direct administration to the CNS.
Evaluation of the therapeutic potential of a CNP analog in a Fgfr3 mouse model recapitulating achondroplasia
Am J Hum Genet. 2012 Dec 7;91(6):1108-14. doi: 10.1016/j.ajhg.2012.10.014. Epub 2012 Nov 29.
Achondroplasia (ACH), the most common form of dwarfism, is an inherited autosomal-dominant chondrodysplasia caused by a gain-of-function mutation in fibroblast-growth-factor-receptor 3 (FGFR3). C-type natriuretic peptide (CNP) antagonizes FGFR3 downstream signaling by inhibiting the pathway of mitogen-activated protein kinase (MAPK). Here, we report the pharmacological activity of a 39 amino acid CNP analog (BMN 111) with an extended plasma half-life due to its resistance to neutral-endopeptidase (NEP) digestion. In ACH human growth-plate chondrocytes, we demonstrated a decrease in the phosphorylation of extracellular-signal-regulated kinases 1 and 2, confirming that this CNP analog inhibits fibroblast-growth-factor-mediated MAPK activation. Concomitantly, we analyzed the phenotype of Fgfr3(Y367C/+) mice and showed the presence of ACH-related clinical features in this mouse model. We found that in Fgfr3(Y367C/+) mice, treatment with this CNP analog led to a significant recovery of bone growth. We observed an increase in the axial and appendicular skeleton lengths, and improvements in dwarfism-related clinical features included flattening of the skull, reduced crossbite, straightening of the tibias and femurs, and correction of the growth-plate defect. Thus, our results provide the proof of concept that BMN 111, a NEP-resistant CNP analog, might benefit individuals with ACH and hypochondroplasia.
Intrathecal recombinant human 4-sulfatase reduces accumulation of glycosaminoglycans in dura of mucopolysaccharidosis VI cats
Pediatr Res. 2012 Jan;71(1):39-45. doi: 10.1038/pr.2011.13.
INTRODUCTION: Mucopolysaccharidosis VI (MPS-VI) is caused by a deficiency in N-acetylgalactosamine-4-sulfatase activity, resulting in lysosomal accumulation of partially degraded glycosaminoglycans (GAGs). Compressive myelopathy in early-onset MPS-VI patients has been partly attributed to thickening of the dura mater following engorgement with GAG. In this study, we therefore tested whether the dural abnormalities could be prevented in a feline model of the disorder.
RESULTS: All intrathecal injections (IT-INJs) were well tolerated. MPS-VI cats treated with IT-INJ of recombinant human N-acetylgalactosamine-4-sulfatase (rhASB) exhibited reduced vacuolation in the dural fibroblasts, diminished levels of sulfated-N-acetylhexosamine (HNAc(+S)) in the cerebrospinal fluid (CSF) and no hind-limb paresis. Serum anti-rhASB antibodies remained low in MPS-VI cats treated with intravenous enzyme replacement therapy (IV-ERT) and increased slightly in normal cats treated with IT-INJ of rhASB alone. Anti-rhASB antibodies in CSF remained undetectable.
DISCUSSION: These data indicate that repeated IT-INJ of rhASB can safely prevent GAG storage in MPS-VI dura.
METHODS: Cats were assigned to three groups: (i) receiving weekly IV-ERT of rhASB from birth plus six monthly IT-INJs of rhASB from age 2 months; (ii) receiving six monthly IT-INJs of vehicle; or (iii) untreated. Additional normal cats received five fortnightly IT-INJs of rhASB or vehicle alone.
Intrathecal tripeptidyl-peptidase 1 reduces lysosomal storage in a canine model of late infantile neuronal ceroid lipofuscinosis
Mol Genet Metab. 2011 Nov;104(3):325-37. doi: 10.1016/j.ymgme.2011.06.018. Epub 2011 Jun 30.
Late infantile neuronal ceroid lipofuscinosis (LINCL) is caused by mutations in the gene encoding tripeptidyl-peptidase 1 (TPP1). LINCL patients accumulate lysosomal storage materials in the CNS accompanied by neurodegeneration, blindness, and functional decline. Dachshunds homozygous for a null mutation in the TPP1 gene recapitulate many symptoms of the human disease. The objectives of this study were to determine whether intrathecal (IT) TPP1 treatment attenuates storage accumulation and functional decline in TPP1-/- Dachshunds and to characterize the CNS distribution of TPP1 activity. TPP1 was administered to one TPP1-/- and one homozygous wild-type (WT) dog. An additional TPP1-/- and WT dog received vehicle. Four IT administrations of 32 mg TPP1 formulated in 2.3 mL of artificial cerebrospinal fluid (aCSF) or vehicle were administered monthly via the cerebellomedullary cistern from four to seven months of age. Functional decline was assessed by physical and neurological examinations, electrophysiology, and T-maze performance. Neural tissues were collected 48 h after the fourth administration and analyzed for TPP1 activity and autofluorescent storage material. TPP1 was distributed at greater than WT levels in many areas of the CNS of the TPP1-/- dog administered TPP1. The amount of autofluorescent storage was decreased in this dog relative to the vehicle-treated affected control. No improvement in overall function was observed in this dog compared to the vehicle-treated TPP1-/- littermate control. These results demonstrate for the first time in a large animal model of LINCL widespread delivery of biochemically active TPP1 to the brain after IT administration along with a decrease in lysosomal storage material. Further studies with this model will be necessary to optimize the dosing route and regimen to attenuate functional decline.
Bi-modal dose-dependent cardiac response to tetrahydrobiopterin in pressure-overload induced hypertrophy and heart failure
J Mol Cell Cardiol. 2011 Oct;51(4):564-9. doi: 10.1016/j.yjmcc.2011.05.017. Epub 2011 May 30.
The exogenous administration of tetrahydrobiopterin (BH4), an essential cofactor of nitric oxide synthase (NOS), has been shown to reduce left ventricular hypertrophy, fibrosis, and cardiac dysfunction in mice with pre-established heart disease induced by pressure-overload. In this setting, BH4 re-coupled endothelial NOS (eNOS), with subsequent reduction of NOS-dependent oxidative stress and reversal of maladaptive remodeling. However, recent studies suggest the effective BH4 dosing may be narrower than previously thought, potentially due to its oxidation upon oral consumption. Accordingly, we assessed the dose response of daily oral synthetic sapropterin dihydrochloride (6-R-l-erythro-5,6,7,8-tetrahydrobiopterin, 6R-BH4) on pre-established pressure-overload cardiac disease. Mice (n=64) were administered 0-400mg/kg/d BH4 by ingesting small pre-made pellets (consumed over 15-30 min). In a dose range of 36-200mg/kg/d, 6R-BH4 suppressed cardiac chamber remodeling, hypertrophy, fibrosis, and oxidative stress with pressure-overload. However, at both lower and higher doses, BH4 had less or no ameliorative effects. The effective doses correlated with a higher myocardial BH4/BH2 ratio. However, BH2 rose linearly with dose, and at the 400mg/kg/d, this lowered the BH4/BH2 ratio back toward control. These results expose a potential limitation for the clinical use of BH4, as variability of cellular redox and perhaps heart disease could produce a variable therapeutic window among individuals. This article is part of a special issue entitled ''Key Signaling Molecules in Hypertrophy and Heart Failure.''
Biodistribution and pharmacodynamics of recombinant human alpha-L-iduronidase (rhIDU) in mucopolysaccharidosis type I-affected cats following multiple intrathecal administrations
Mol Genet Metab. 2011 Jul;103(3):268-74. doi: 10.1016/j.ymgme.2011.03.011. Epub 2011 Mar 21.
The storage disorder mucopolysaccharidosis type I (MPS I) is caused by a deficiency in lysosomal α-L-iduronidase activity. The inability to degrade glycosaminoglycans (GAG) results in lysosomal accumulation and widespread tissue lesions. Many symptoms of MPS I are amenable to treatment with recombinant human α-L-iduronidase (rhIDU), however, peripherally administered rhIDU does not cross the blood-brain barrier and has no beneficial effects in the central nervous system (CNS). A feline model of MPS I was used to evaluate the CNS effects of rhIDU following repeated intrathecal (IT) administration. Twelve animals were randomized into four groups based on the time of euthanasia and tissue evaluation following three repeat IT administrations of 0.1 mg/kg rhIDU or placebo on Study Days 1, 4 or 5, and 9. Two days after the final IT injection, the mean tissue α-L-iduronidase (IDU) activity in the brains of the two treated animals were approximately 3-times higher (50.1 and 54.9 U/mg protein) than the activity found in normal cat brains (mean of 18.3 U/mg), and remained higher than untreated MPSI brain at 1 month (2.4 and 4.1 U/mg protein) before returning to near-baseline levels after 2 months. This activity corresponded with decreased brain GAG concentrations after 2 days (1.4 and 2.0 μg/mg) and 1 month (0.9 and 1.1 μg/mg) which approached levels observed in normal animals (0.7 μg/mg). Attenuation of GAG, gangliosides GM2 and GM3, and cholesterol reaccumulation was identified at both two days and one month following final IT injection. No adverse effects attributable to IT rhIDU administration were observed. IT rhIDU may be an effective means for providing enzyme replacement therapy for the central manifestations of MPS I.
The pharmacologic assessment of a novel lymphocyte function-associated antigen-1 antagonist (SAR 1118) for the treatment of keratoconjunctivitis sicca in dogs
Invest Ophthalmol Vis Sci. 2011 May 16;52(6):3174-80. doi: 10.1167/iovs.09-5078.
PURPOSE: Keratoconjunctivitis sicca (KCS) is characterized by inflammation and decreased production of tears containing increased levels of cytokines. The release occurs in the setting of conjunctival and lacrimal gland inflammation, potentially mediated by the interaction between lymphocyte function-associated antigen (LFA)-1, a cell surface protein found on lymphocytes, and its cognate ligand intercellular adhesion molecule (ICAM)-1. SAR 1118 is a novel LFA-1 antagonist and may be an effective therapeutic agent for the treatment of KCS. The following studies were performed to assess the in vitro activity of SAR 1118 and to evaluate the clinical efficacy of topical SAR 1118 for the treatment of idiopathic canine KCS.
METHOD: Pharmacodynamics were assessed by measuring the ability of SAR 1118 to inhibit Jurkat T-cell binding with recombinant human ICAM-1 and to inhibit cytokine release from human peripheral blood mononuclear cells (PBMCs) stimulated by staphylococcal enterotoxin B. For the assessment of clinical efficacy, 10 dogs diagnosed with idiopathic KCS were treated with SAR 1118 1% topical ophthalmic solution three times daily for 12 weeks. Schirmer's tear test (STT) was used to measure tear production.
RESULTS: SAR 1118 demonstrated concentration-dependent inhibition of Jurkat T-cell attachment, inhibition of lymphocyte activation, and release of inflammatory cytokines, particularly the Th1, Th2, and Th17 T-cell cytokines IFN-γ, IL-2, and IL-17F, respectively. Mean STT values increased from 3.4 mm during week 1 to 5.8 mm at week 12 (P < 0.025). No SAR 1118-related adverse events were observed.
CONCLUSIONS: SAR 1118 appears to be an effective anti-inflammatory treatment for KCS. Additional studies are warranted to establish the efficacy of SAR 1118 for the treatment of KCS in humans.
Delivery of SAR 1118 to the retina via ophthalmic drops and its effectiveness in a rat streptozotocin (STZ) model of diabetic retinopathy (DR)
Invest Ophthalmol Vis Sci. 2010 Oct;51(10):5198-204. doi: 10.1167/iovs.09-5144. Epub 2010 May 5.
PURPOSE: To determine the pharmacokinetics of SAR 1118, a small-molecule antagonist of leukocyte function-associated antigen (LFA)-1, after administration of ophthalmic drops in normal rats, and to determine its pharmacologic activity by assessing the inhibition of retinal leukostasis and vascular leakiness in a streptozotocin (STZ)-induced diabetic retinopathy model.
METHODS: The ocular pharmacokinetics of SAR 1118 were studied in rats after a single topical dose of (14)C-SAR 1118 (1 mg/eye; 40 μCi; 15.5 μL). SAR 1118 concentration time profiles in plasma and ocular tissues were quantified by liquid scintillation counting (LSC). The pharmacologic activity of SAR 1118 eye drops administered thrice daily for 2 months at 1% (0.3 mg/eye/d) and 5% (1.5 mg/eye/d) was assessed in an STZ-induced diabetic rat model by determining retinal leukostasis and blood-retinal barrier breakdown. Diabetic rats treated with periocularly administered celecoxib microparticles served as the positive control, and vehicle-treated rats served as the negative control.
RESULTS: A single dose of 6.5% (14)C-radiolabeled SAR 1118 ophthalmic drops delivered retinal drug levels greater than 1 μM in less than 30 minutes and sustained levels greater than 100 nM for 8 hours. SAR 1118 eye drops significantly reduced leukostasis and blood-retinal barrier breakdown in a dose-dependent manner.
CONCLUSIONS: SAR 1118 ophthalmic drops administered thrice daily deliver therapeutic levels of SAR 1118 in the retina and can alleviate the retinal complications associated with diabetes.
Tetrahydrobiopterin supplementation reduces atherosclerosis and vascular inflammation in apolipoprotein E-knockout mice
Clin Sci (Lond). 2010 May 6;119(3):131-42. doi: 10.1042/CS20090559.
BH4 (tetrahydrobiopterin) supplementation improves endothelial function in models of vascular disease by maintaining eNOS (endothelial nitric oxide synthase) coupling and NO (nitric oxide) bioavailability. However, the cellular mechanisms through which enhanced endothelial function leads to reduced atherosclerosis remain unclear. We have used a pharmaceutical BH4 formulation to investigate the effects of BH4 supplementation on atherosclerosis progression in ApoE-KO (apolipoprotein E-knockout) mice. Single oral dose pharmacokinetic studies revealed rapid BH4 uptake into plasma and organs. Plasma BH4 levels returned to baseline by 8 h after oral dosing, but remained markedly increased in aorta at 24 h. Daily oral BH4 supplementation in ApoE-KO mice from 8 weeks of age, for a period of 8 or 12 weeks, had no effect on plasma lipids or haemodynamic parameters, but significantly reduced aortic root atherosclerosis compared with placebo-treated animals. BH4 supplementation significantly reduced VCAM-1 (vascular cell adhesion molecule 1) mRNA levels in aortic endothelial cells, markedly reduced the infiltration of T-cells, macrophages and monocytes into plaques, and reduced T-cell infiltration in the adjacent adventitia, but importantly had no effect on circulating leucocytes. GCH (GTP cyclohydrolase I)-transgenic mice, with a specific increase in endothelial BH4 levels, exhibited a similar reduction in vascular immune cell infiltration compared with BH4-deficient controls, suggesting that BH4 reduces vascular inflammation via endothelial cell signalling. In conclusion, BH4 supplementation reduces vascular immune cell infiltration in atherosclerosis and may therefore be a rational therapeutic approach to reduce the progression of atherosclerosis.
Repeated intrathecal injections of recombinant human 4-sulphatase remove dural storage in mature mucopolysaccharidosis VI cats primed with a short-course tolerisation regimen
Mol Genet Metab. 2010 Feb;99(2):132-41. doi: 10.1016/j.ymgme.2009.10.002. Epub 2009 Oct 13.
All MPS-VI cats treated thus far with weekly intravenous enzyme replacement therapy (IV ERT) with recombinant human N-acetylgalactosamine-4-sulphatase (rhASB) from 3 months of age onwards developed circulating anti-rhASB antibodies. In view of this, the possibility of inducing immune tolerance by using a short-course tolerisation regimen was tested. Starting at 4 months of age, MPS-VI (n=5) and unaffected cats (n=2) received cyclosporine and azathioprine over a 22-day period plus weekly IV ERT with 0.1mg/kg rhASB. After a 4-week resting period, these cats were administered weekly IV ERT with 1mg/kg rhASB until 11 or 17 months of age. Four unaffected cats (n=4) received weekly IV ERT only. Health, growth and seroconversion were regularly monitored. Four out of five MPS-VI cats tolerated rhASB well, as indicated by negligible or low antibody titres and absence of hypersensitivity reactions. One MPS-VI cat exhibited elevated antibody titres and hypersensitivity reactions during some IV treatments. The two unaffected cats that received the tolerisation regimen remained seronegative, however, only half of the unaffected cats not submitted to this regimen seroconverted. Only minor side-effects were attributed to the short-course of cyclosporine and azathioprine. Two MPS-VI cats also well-tolerated four weekly intrathecal injections of rhASB and consequently exhibited less oligosaccharide fragments in cerebrospinal fluid and less vacuolation within their dura mater. These data indicate that a relatively high rate of immunotolerance towards rhASB can be achieved in MPS-VI cats with a short-course tolerisation regimen ultimately permitting removal of lysosomal storage within the dura mater with the use of intrathecal therapy.
Characterization of a Monkey Model of Laser-Induced Choroidal Neovascularization (CNV)
The Toxicologist, 72 (S-1): 311, (2003)
26-Week Intravitreal Injection Toxicity Study with rhuFab VEGF in Cynomolgus Monkeys with an 8-Week Recovery
Association for Research in Vision and Ophthalmology Annual Meeting. Invest Ophthalmol Vis Sci., 44 – electronic abstract (2003).
Safety Evaluation of Differing Schedules of Intravitreal Administration of rhuFab VEGF in Cynomolgus Monkeys for 2 Months
Toxicologist, 60 (1):97 (2001).
Safety Evaluation of Intravitreal Administration of rhuFab VEGF in Cynomolgus Monkeys for 3 Months
Invest Ophthalmol Vis Sci, 41 (4):S142 (2000).