Clinical immunogenicity outcomes from GENEr8-1, a phase 3 study of valoctocogene roxaparvovec, an AAV5-vectored gene therapy for hemophilia A.

Gene transfer therapies utilizing adeno-associated virus (AAV) vectors involve a complex drug design with multiple components that may impact immunogenicity. Valoctocogene roxaparvovec is an AAV serotype 5 (AAV5)-vectored gene therapy for the treatment of hemophilia A that encodes a B-domain-deleted human factor VIII (FVIII) protein controlled by a hepatocyte-selective promoter. Following previous results from the first-in-human phase 1/2 clinical trial, we assessed AAV5-capsid- and transgene-derived FVIII-specific immune responses with 2 years of follow-up data from GENEr8-1, a phase 3, single-arm, open-label study in 134 adult men with severe hemophilia A. No FVIII inhibitors were detected following administration of valoctocogene roxaparvovec. Immune responses were predominantly directed toward the AAV5 capsid, with all participants developing durable anti-AAV5 antibodies. Cellular immune responses specific for the AAV5 capsid were detected in most participants by interferon-γ enzyme-linked immunosorbent spot assay 2 weeks following dose administration and declined or reverted to negative over the first 52 weeks. These responses were weakly correlated with alanine aminotransferase elevations and showed no association with changes in FVIII activity. FVIII-specific cellular immune responses were less frequent and more sporadic compared with those specific for AAV5 and showed no association with safety or efficacy parameters.

Achieving efficacy in subjects with sustained pegvaliase-neutralizing antibody responses.

Pegvaliase (Palynziq®) is an enzyme substitution therapy using PEGylated recombinant Anabaena variabilis phenylalanine ammonia lyase (PAL) to reduce blood phenylalanine (Phe) levels in adults with phenylketonuria (PKU). In Phase 3 clinical studies, all subjects treated with pegvaliase developed anti-drug antibodies. To specifically evaluate pegvaliase-neutralizing antibodies (NAbs) and assess impact on pegvaliase efficacy, a novel hybrid ligand-binding/tandem mass spectrometry NAb assay was developed. Analysis of Phase 3 study samples revealed that pegvaliase NAb titers developed during early treatment (≤6 months after treatment initiation), and then plateaued and persisted in the majority of subjects during late treatment (>6 months). Subjects with the lowest/undetectable NAb titers had relatively high plasma pegvaliase concentrations and experienced the most rapid decline in blood Phe concentrations at relatively low pegvaliase dose concentrations. In contrast, subjects with higher NAb titers generally had lower plasma pegvaliase concentrations on similar low doses, with little change in blood Phe concentrations. However, with additional time on treatment and individualized dose titration, the majority of subjects achieved substantial and sustained blood Phe reduction, including those with higher NAb titers. Moreover, after maturation of the anti-pegvaliase immune response, NAb titers were stable over time and did not rise in response to dose increases; thus, subjects did not require additional dose increases to maintain reduction in blood Phe.

Monitoring cell-mediated immune responses in AAV gene therapy clinical trials using a validated IFN-γ ELISpot method.

Adeno-associated virus (AAV)-based gene therapies have recently shown promise as a novel treatment for hereditary diseases. Due to the viral origin of the vector capsid, however, cellular immune response may be elicited that could eliminate transduced target cells. To monitor cellular immune responses in clinical trials, we optimized and bioanalytically validated a sensitive, robust, and reliable interferon-γ (IFN-γ) enzyme-linked immunospot (ELISpot) assay. For method performance validation, human peripheral blood mononuclear cells (PBMCs) were stimulated with peptides derived from AAV5 capsid proteins and the encoded transgene product, human blood clotting factor VIII (FVIII), in addition to positive controls, such as peptides from the 65-kDa phosphoprotein of cytomegalovirus. We statistically assessed the limit of detection and confirmatory cutpoint, evaluated precision and linearity, and confirmed specificity using HIV peptides. Robustness parameter ranges and sample stability periods were established. The validated IFN-γ ELISpot assay was then implemented in an AAV5-FVIII gene therapy clinical trial. Cellular immune responses against the AAV5 capsid were observed in most participants as soon as 2 weeks following dose administration; only limited responses against the transgene product were detected. These data underscore the value of using validated methods for monitoring cellular immunity in AAV gene therapy trials.

COVID-19-associated ischaemic stroke due to underlying carotid artery thrombosis in a healthy young woman.

SARS-CoV-2 has proven its versatility in host presentations; one such presentation is a hypercoagulable state causing large-vessel thrombosis. We report a case on a previously asymptomatic COVID-19-positive patient presenting with an acute ischaemic stroke and an incidental left internal carotid artery thrombus. The patient's medical, social and family history and hypercoagulability screening excluded any other explanation for the left carotid thrombus or stroke, except for testing positive for the COVID-19. This case explores the known hypercoagulable state associated with COVID-19 and the effect of the virus on the host's immune response. It also questions whether administration of recombinant tissue plasminogen activator (t-PA), according to the American Heart Association guidelines, following a negative head CT for haemorrhagic stroke is safe without prior extended imaging in this patient population. We recommend, in addition to obtaining a non-contrast CT scan of the brain, a CT angiogram or carotid duplex of the neck be obtained routinely in patients with COVID-19 exhibiting stroke symptoms before t-PA administration as the effects may be detrimental. This recommendation will likely prevent fragmentation and embolisation of an undetected carotid thrombus.

Development and pilot evaluation of the Cognition domain of the Hong Kong Comprehensive Assessment Scales for Toddlers.

Purpose: To describe the development of the Cognition domain of the Hong Kong Comprehensive Assessment Scales for Toddlers (HKCAS-T).Methods: Participants included 345 toddlers aged 18-41 months, with 258 recruited from Maternal and Child Health Centers (MCHCs) and 87 with cognitive delay recruited from Child Assessment Centers (CACs). They were individually administered the 83-item pilot version by medical practitioners or educational psychologists between 2017 and 2019 in MCHCs and CACs in Hong Kong.Results: Rasch analysis results supported the unidimensionality of the pilot version, after removing six items. Analysis of covariance results indicated that both the 83-item version and the 77-item version could differentiate between children of different age groups, and children with typical development from children with cognitive delay. Internal consistency and interrater reliability were 0.90 or above.Conclusions: The Cognition domain of the HKCAS-T is a promising developmental assessment tool for the assessment of toddlers. Cognition assessment, preschool, Chinese.

Early Phase Clinical Immunogenicity of Valoctocogene Roxaparvovec, an AAV5-Mediated Gene Therapy for Hemophilia A.

Evaluation of immune responses to adeno-associated virus (AAV)-mediated gene therapies prior to and following dose administration plays a key role in determining therapeutic safety and efficacy. This report describes up to 3 years of immunogenicity data following administration of valoctocogene roxaparvovec (BMN 270), an AAV5-mediated gene therapy encoding human B domain-deleted FVIII (hFVIII-SQ) in a phase 1/2 clinical study of adult males with severe hemophilia A. Patients with pre-existing humoral immunity to AAV5 or with a history of FVIII inhibitors were excluded from the trial. Blood plasma and peripheral blood mononuclear cell (PBMC) samples were collected at regular intervals following dose administration for assessment of humoral and cellular immune responses to both the AAV5 vector and transgene-expressed hFVIII-SQ. The predominant immune response elicited by BMN 270 administration was largely limited to the development of antibodies against the AAV5 capsid that were cross-reactive with other common AAV serotypes. No FVIII inhibitor responses were observed within 3 years following dose administration. In a context of prophylactic or on-demand corticosteroid immunosuppression given after vector infusion, AAV5 and hFVIII-SQ peptide-specific cellular immune responses were intermittently detected by an interferon (IFN)-γ and tumor necrosis factor (TNF)-α FluoroSpot assay, but they were not clearly associated with detrimental safety events or changes in efficacy measures.

The Sec1/Munc18 protein Vps45 holds the Qa-SNARE Tlg2 in an open conformation.

Fusion of intracellular trafficking vesicles is mediated by the assembly of SNARE proteins into membrane-bridging complexes. SNARE-mediated membrane fusion requires Sec1/Munc18-family (SM) proteins, SNARE chaperones that can function as templates to catalyze SNARE complex assembly. Paradoxically, the SM protein Munc18-1 traps the Qa-SNARE protein syntaxin-1 in an autoinhibited closed conformation. Here we present the structure of a second SM-Qa-SNARE complex, Vps45-Tlg2. Strikingly, Vps45 holds Tlg2 in an open conformation, with its SNARE motif disengaged from its Habc domain and its linker region unfolded. The domain 3a helical hairpin of Vps45 is unfurled, exposing the presumptive R-SNARE binding site to allow template complex formation. Although Tlg2 has a pronounced tendency to form homo-tetramers, Vps45 can rescue Tlg2 tetramers into stoichiometric Vps45-Tlg2 complexes. Our findings demonstrate that SM proteins can engage Qa-SNAREs using at least two different modes, one in which the SNARE is closed and one in which it is open.

Pegvaliase for the treatment of phenylketonuria: Results of the phase 2 dose-finding studies with long-term follow-up.

BACKGROUND: Phenylketonuria (PKU) is characterized by a deficiency in phenylalanine hydroxylase (PAH) that may lead to elevated blood phenylalanine (Phe) and significant neurocognitive and neuropsychological comorbidities. Pegvaliase (PALYNZIQ®, BioMarin Pharmaceutical Inc.) is a PEGylated recombinant Anabaena variabilis phenylalanine ammonia lyase (PAL), which converts Phe to trans-cinnamic acid and ammonia, and was approved in May 2018 in the United States and in May 2019 in the European Union for decreasing blood Phe levels in adults with PKU with blood Phe levels >600 µmol/L. The efficacy and safety of pegvaliase was assessed in two phase 2 dose-finding studies in adults with PKU (PAL-002, NCT00925054, and PAL-004, NCT01212744). Participants completing these studies could enroll in a long-term extension study (PAL-003, NCT00924703). METHODS: Participants in PAL-002 received pegvaliase 0.001, 0.003, 0.01, 0.03, or 0.1 mg/kg weekly for 8 weeks, then continued treatment for a further 8 weeks with dose and/or frequency adjusted to achieve blood Phe concentrations of 60 to 600 µmol/L. Participants in PAL-004 received pegvaliase 0.001 to 0.4 mg/kg 5 days/week for 13 weeks, with modifications made to the starting dose in response to safety and/or efficacy, followed by 3 additional weeks of follow-up assessments. The maximum allowable daily dose in both studies was 1.0 mg/kg/day (5.0 mg/kg/week). Participants who completed any of the phase 2 studies (PAL-002; PAL-004; or a third phase 2 study, 165-205) were eligible to enroll in an open-label, multicenter, long-term extension study (PAL-003, NCT00924703). RESULTS: Thirty-seven of the 40 enrolled participants completed PAL-002 and 15 of the 16 enrolled participants completed PAL-004. Mean blood Phe at baseline was 1311.0 (standard deviation [SD] 354) µmol/L in PAL-002 and 1482.1 (SD 363.5) µmol/L in PAL-004. Mean blood Phe did not substantially decrease with pegvaliase treatment in PAL-002 (-206.3 [SD 287.1] µmol/L at Week 16) or PAL-004 (-410.8 [SD 653.7] µmol/L at Week 13). In PAL-004, mean blood Phe dropped from baseline by 929.1 µmol/L (SD 691.1) by Week 2; subsequent to dose modifications and interruptions, this early decrease in mean Phe level was not sustained. With increased pegvaliase dose and duration in PAL-003, mean blood Phe levels steadily decreased from baseline, with mean reductions by Week 120 of 68.8% (SD 44.2%) in PAL-002 participants and 75.9% (SD 32.4%) in PAL-004 participants. All participants in PAL-002 and PAL-004 reported ≥1 adverse event (AE), with higher exposure-adjusted event rates in PAL-004. The majority of AEs were mild (87.2% in PAL-002, 86.7% in PAL-004) or moderate (12.4% in PAL-002, 13.3% in PAL-004). The most commonly reported AEs in PAL-002 were injection site reaction (50.0% of participants), headache (42.1%), injection site erythema (36.8%), nausea (34.2%), and arthralgia (29.0%), and in PAL-004 were arthralgia (75.0%), headache (62.5%), dizziness (56.3%), injection site erythema (56.3%), and injection site reaction (50.0%). CONCLUSIONS: In two phase 2 dose-finding studies, pegvaliase did not lead to substantial blood Phe reductions. Higher and more frequent pegvaliase dosing in PAL-004 led to a substantial initial drop in blood Phe, but an increase in the number of hypersensitivity AEs and dose reductions or interruptions. With increased dose and duration of treatment in PAL-003, mean blood Phe reduction was substantial and sustained, and the frequency of hypersensitivity AEs decreased and stabilized. Together, these studies led to the development of an induction-titration-maintenance regimen that has been approved for pegvaliase, with patients starting at a low weekly dose that gradually increases in dose and frequency until they achieve a standard non-weight-based daily maintenance dose. This regimen has been tested in a third phase 2 study, as well as in two successful phase 3 studies of pegvaliase.

Depletion of interfering IgG and IgM is critical to determine the role of IgE in pegvaliase-associated hypersensitivity.

Pegvaliase is an enzyme substitution therapy developed to lower blood phenylalanine (Phe) in adults with phenylketonuria (PKU). In phase 3 clinical studies, pegvaliase substantially reduced mean blood Phe in adult subjects with PKU. The most common type of adverse event observed in the pegvaliase clinical program was hypersensitivity adverse events (HAEs), which included occurrences of arthralgia, rash, and pruritis. The most clinically relevant HAEs were acute systemic hypersensitivity reactions consistent with anaphylaxis observed in 4.6% of phase 3 patients. HAEs were more commonly observed around the time of high circulating immune complex (CIC) levels and complement activation, and the majority of subjects that experienced acute systemic hypersensitivity events were able to continue treatment, which is atypical for a classical IgE-mediated anaphylactic event, but common for type III hypersensitivity reactions. To investigate the alternative mechanism of type III hypersensitivity, serum samples collected shortly after hypersensitivity events (in phase 2 and 3 studies) were tested for anti-pegvaliase IgE using custom radioallergosorbent test and/or ImmunoCAP® (ThermoFisher Scientific, Waltham, MA) assay methods. All subjects with acute systemic hypersensitivity that were tested for anti-pegvaliase IgE at or near the time of event with one or both assays tested negative for IgE. As presented here, an investigation using selected study samples with high anti-drug antibody (ADA) titers demonstrated that presence of IgM and/or IgG ADA can interfere with measurement of a human anti-pegvaliase IgE surrogate positive control. A depletion method was therefore developed using protein A- and G-conjugated Sepharose to remove interfering IgG and IgM in serum samples to low levels (<45 mg/dL) before IgE testing. A final 2× concentration step brought the IgE concentration in the depleted sample to approximately the same level of the starting serum. Phase 3 study samples with sufficient volume remaining that previously tested negative for anti-pegvaliase IgE were re-tested after depletion of IgG and IgM. All samples again tested negative, confirming the original test results. Taken together, the clinical presentation, temporal association of HAEs with CIC levels and complement activation, and lack of anti-pegvaliase IgE suggest pegvaliase-associated acute systemic hypersensitivity events were not IgE-mediated. Furthermore, we describe a universal method that is broadly applicable to enzyme therapies for detection of low concentrations of drug-specific IgE in the presence of high titer anti-drug antibodies of different isotypes.

Association of immune response with efficacy and safety outcomes in adults with phenylketonuria administered pegvaliase in phase 3 clinical trials.

BACKGROUND: This study assessed the immunogenicity of pegvaliase (recombinant Anabaena variabilis phenylalanine [Phe] ammonia lyase [PAL] conjugated with polyethylene glycol [PEG]) treatment in adults with phenylketonuria (PKU) and its impact on safety and efficacy. METHODS: Immunogenicity was assessed during induction, upward titration, and maintenance dosing regimens in adults with PKU (n = 261). Total antidrug antibodies (ADA), neutralizing antibodies, immunoglobulin (Ig) M and IgG antibodies against PAL and PEG, IgG and IgM circulating immune complex (CIC) levels, complement components 3 and 4 (C3/C4), plasma Phe, and safety were assessed at baseline and throughout the study. Pegvaliase-specific IgE levels were measured in patients after hypersensitivity adverse events (HAE). FINDINGS: All patients developed ADA against PAL, peaking by 6 months and then stabilizing. Most developed transient antibody responses against PEG, peaking by 3 months, then returning to baseline by 9 months. Binding of ADA to pegvaliase led to CIC formation and complement activation, which were highest during early treatment. Blood Phe decreased over time as CIC levels and complement activation declined and pegvaliase dosage increased. HAEs were most frequent during early treatment and declined over time. No patient with acute systemic hypersensitivity events tested positive for pegvaliase-specific IgE near the time of the event. Laboratory evidence was consistent with immune complex-mediated type III hypersensitivity. No evidence of pegvaliase-associated IC-mediated end organ damage was noted. INTERPRETATION: Despite a universal ADA response post-pegvaliase administration, adult patients with PKU achieved substantial and sustained blood Phe reductions with a manageable safety profile. FUND: BioMarin Pharmaceutical Inc.

Long-term safety and efficacy of pegvaliase for the treatment of phenylketonuria in adults: combined phase 2 outcomes through PAL-003 extension study.

BACKGROUND: Deficiency of phenylalanine hydroxylase causes phenylketonuria (PKU) with elevated phenylalanine (Phe) levels and associated neuropsychiatric and neurocognitive symptoms. Pegvaliase (PEGylated phenylalanine ammonia lyase) is an investigational agent to lower plasma Phe in adults with PKU. This study aimed to characterize the long-term efficacy, safety, and immunogenicity of pegvaliase in adults with PKU. METHODS: PAL-003 is an ongoing, open-label, long-term extension study of the pegvaliase dose-finding parent phase 2 studies. Participants continued the dose of pegvaliase from one of three parent studies, with dose adjustments to achieve a plasma Phe concentration between 60 and 600 µmol/L. RESULTS: Mean (standard deviation [SD]) plasma Phe at treatment-naïve baseline for 80 participants in the parent studies was 1302.4 (351.5) µmol/L. In the 68 participants who entered the extension study, plasma Phe decreased 58.9 (39)% from baseline, to 541.6 (515.5) µmol/L at Week 48 of treatment. Plasma Phe concentrations ≤120 µmol/L, ≤360 µmol/L, and ≤ 600 µmol/L were achieved by 78.7, 80.0, and 82.5% of participants, respectively. Mean (SD) protein intake at baseline was 69.4 (40.4) g/day (similar to the recommended intake for the unaffected population) and remained stable throughout the study. All participants experienced adverse events (AEs), which were limited to mild or moderate severity in most (88.8%); the most common AEs were injection-site reaction (72.5%), injection-site erythema (67.5%), headache (67.5%), and arthralgia (65.0%). The AE rate decreased from 58.3 events per person-year in the parent studies to 18.6 events per person-year in the extension study. CONCLUSIONS: Pegvaliase treatment in adults with PKU produced meaningful and persistent reductions in mean plasma Phe concentration with a manageable safety profile for most subjects that continued with long-term treatment. TRIAL REGISTRATION: ClinicalTrials.gov , NCT00924703. Registered June 18, 2009, https://clinicaltrials.gov/ct2/show/NCT00924703.

Immunogenicity of Elosulfase Alfa, an Enzyme Replacement Therapy in Patients With Morquio A Syndrome: Results From MOR-004, a Phase III Trial.

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.

Traditional cardiovascular risk factors and the presence of obstructive coronary artery disease in men and women.

BACKGROUND: Extensive research has demonstrated the importance of traditional cardiovascular risk factors in predicting acute coronary events. Our main objective was to evaluate the relationship between traditional risk factors and the presence of obstructive coronary artery disease (CAD), and to explore potential differences in men vs women. METHODS: An observational study was conducted in a population-based cohort of stable patients who underwent cardiac catheterization in Ontario, Canada. We examined the relationship of diabetes, hypertension, hyperlipidemia, and smoking with the presence of obstructive CAD in men and women using multivariable logistic regression models. RESULTS: Of the 46,490 patients who were included in our study, 61.2% were men and 38.8% were women. We found that 97% of patients with obstructive CAD had at least 1 conventional cardiovascular risk factor. The adjusted odds ratios (ORs) for obstructive CAD in women with diabetes (OR, 1.51), hypertension (OR, 1.38), and smoking (OR, 1.39) were statistically significantly greater than in men (OR, 1.20 for diabetes; OR, 1.08 for hypertension; OR, 1.14 for smoking; P < 0.001). The sex difference was even greater for patients with multiple risk factors. For example, the association with obstructive CAD in women with 4 cardiac risk factors (OR, 4.30; 95% confidence interval, 3.49-5.28) was almost doubled compared with men (OR, 2.26; 95%confidence interval, 1.99-2.57; P < 0.001). CONCLUSIONS: Almost all patients with stable CAD undergoing cardiac catheterization had at least 1 traditional cardiac risk factor. Importantly, the association between multiple cardiac risk factors and the presence of obstructive CAD is substantially stronger in women than men.

Adverse effects associated with transcatheter aortic valve implantation: a meta-analysis of contemporary studies.

BACKGROUND: Transcatheter aortic valve implantation (TAVI) has emerged as an important treatment for patients with severe symptomatic aortic stenosis who are at high operative risk, but accurate estimates of serious adverse effects in contemporary practice are not available. PURPOSE: To quantify the adverse effects associated with TAVI, and to evaluate whether the type of transcatheter valve and the route of valve implantation are associated with differences in adverse outcomes. DATA SOURCE: PubMed to 5 May 2012. STUDY SELECTION: All studies that included at least 100 patients who had TAVI and reported at least 1 outcome of interest. DATA EXTRACTION: Two reviewers abstracted the data independently. A random-effects model was used to combine data on adverse outcomes and conduct stratified analyses. DATA SYNTHESIS: A total of 49 studies enrolling 16 063 patients met the inclusion criteria. Overall 30-day and 1-year survival after TAVI were 91.9% (95% CI, 91.1% to 92.8%) and 79.2% (CI, 76.9% to 81.4%), respectively. Heart block requiring permanent pacemaker implantation was the most common adverse outcome (13.1%) and was 5 times more common with the CoreValve (Medtronic, Minneapolis, Minnesota) than the Sapien valve (Edwards Lifesciences, Irving, California) implanted using the transarterial route (25.2% vs. 5.0%, respectively). The overall rate of vascular complications was 10.4% and was highest with transarterial implantation of the Sapien valve (22.3%). Acute renal failure requiring renal replacement therapy was the third most common complication, occurring in 4.9% of patients. LIMITATION: Rates of major vascular complications may be overestimated owing to rapidly evolving TAVI technology. CONCLUSION: The most common adverse effects associated with TAVI are heart block, vascular complications, and renal failure. The type of transcatheter valve and the route of implantation are associated with observed variations in the risks for some adverse effects. PRIMARY FUNDING SOURCE: Heart and Stroke Foundation of Canada.

Cooperative roles of BDNF expression in neurons and Schwann cells are modulated by exercise to facilitate nerve regeneration.

After peripheral nerve injury, neurotrophins play a key role in the regeneration of damaged axons that can be augmented by exercise, although the distinct roles played by neurons and Schwann cells are unclear. In this study, we evaluated the requirement for the neurotrophin, brain-derived neurotrophic factor (BDNF), in neurons and Schwann cells for the regeneration of peripheral axons after injury. Common fibular or tibial nerves in thy-1-YFP-H mice were cut bilaterally and repaired using a graft of the same nerve from transgenic mice lacking BDNF in Schwann cells (BDNF(-/-)) or wild-type mice (WT). Two weeks postrepair, axonal regeneration into BDNF(-/-) grafts was markedly less than WT grafts, emphasizing the importance of Schwann cell BDNF. Nerve regeneration was enhanced by treadmill training posttransection, regardless of the BDNF content of the nerve graft. We further tested the hypothesis that training-induced increases in BDNF in neurons allow regenerating axons to overcome a lack of BDNF expression in cells in the pathway through which they regenerate. Nerves in mice lacking BDNF in YFP(+) neurons (SLICK) were cut and repaired with BDNF(-/-) and WT nerves. SLICK axons lacking BDNF did not regenerate into grafts lacking Schwann cell BDNF. Treadmill training could not rescue the regeneration into BDNF(-/-) grafts if the neurons also lacked BDNF. Both Schwann cell- and neuron-derived BDNF are thus important for axon regeneration in cut peripheral nerves.

Biomarker analysis of Morquio syndrome: identification of disease state and drug responsive markers.

BACKGROUND: This study was conducted to identify potential biomarkers that could be used to evaluate disease progression and monitor responses to enzyme replacement therapy (ERT) in patients with mucopolysaccharidosis (MPS) IVA. METHODS: Levels of 88 candidate biomarkers were compared in plasma samples from 50 healthy controls and 78 MPSIVA patients not receiving ERT to test for significant correlations to the presence of MPSIVA. MPSIVA samples were also tested for correlations between candidate biomarkers and age, endurance, or urinary keratin sulfate (KS) levels. Then, levels of the same 88 analytes were followed over 36 weeks in 20 MPSIVA patients receiving ERT to test for significant correlations related to ERT, age, or endurance. RESULTS: Nineteen candidate biomarkers were significantly different between MPSIVA and unaffected individuals. Of these, five also changed significantly in response to ERT: alpha-1-antitrypsin, eotaxin, lipoprotein(a), matrix metalloprotein (MMP)-2, and serum amyloid P. Three of these were significantly lower in MPSIVA individuals versus unaffected controls and were increased during ERT: alpha-1-antitrypsin, lipoprotein(a), and serum amyloid P. CONCLUSIONS: Candidate biomarkers alpha-1-antitrypsin, lipoprotein(a), and serum amyloid P may be suitable markers, in addition to urinary KS, to follow the response to ERT in MPSIVA patients.