Abstract Mycophenolic acid ( MPA ), a noncompetitive, selective and reversible inhibitor of inosine 5′‐monophosphate dehydrogenase ( IMPDH ), is an immunosuppressive agent that has a long history in medicine. Mechanistically, the inhibition of IMPDH leads to the selective and eventual arrest of T‐ and B‐lymphocyte proliferation. Mycophenolate mofetil ( MMF ), the first MPA ‐based product to receive marketing approval over two decades ago, was originally indicated for the prophylaxis of organ rejection in human transplant patients. Given its broad immunosuppressive properties and ability to selectively inhibit lymphocyte division and effector functions, the clinical utility of MPA was subsequently explored in a host of autoimmune diseases. Human clinical studies have shown MPA to be safe and effective and support its off‐label administration for immune‐mediated diseases such as lupus, myasthenia gravis and atopic dermatitis. MMF became generically available in the United States in 2008, and its clinical utility is increasingly being explored as a treatment option for dogs with immune‐mediated diseases. This review summarizes the available literature for MPA pharmacokinetics and pharmacodynamics, and the current status of MPA as a treatment for client‐owned dogs diagnosed with immune‐mediated diseases.
Background: Glucagon-like peptide-1 (GLP-1) is an incretin hormone that plays an important role in glucose homeostasis and food intake. In people, GLP-1 receptor agonists (GLP-1RAs) are commonly used for the treatment of type 2 diabetes mellitus (DM) and obesity; however, non-adherence to injectable medications is common. OKV-119 is an investigational drug delivery system intended for subdermal implantation and delivery of the GLP-1RA exenatide for up to 6 months. Hypothesis/Objectives: Develop protocols for the subcutaneous (SC) insertion and removal of OKV-119 and to evaluate its tolerability, in vivo drug-releasing characteristics, and weight-loss effects in cats. Animals: Two cadaveric and 19 purpose-bred cats. Methods: In cadavers, OKV-119 insertion protocol and imaging were performed at three SC locations. The safety and tolerability of OKV-119 implants were assessed in a small ( n = 4 cats) 62-day study. Weekly plasma exenatide concentrations and body weight were measured in a 42-day proof-of-concept study designed to evaluate OKV-119 prototypes implanted in cats ( n = 15). Results: In anesthetized cats, the duration of insertion and removal procedures was 1–2 min. OKV-119 was easily identified on radiographs, and well-tolerated without any apparent implant site reactions. Following implantation, exanatide plasma concentrations were observed for up to 35 days. Plasma exenatide concentrations were correlated to weight loss. Conclusion and clinical importance: Our findings suggest that OKV-119 could be easily inserted and removed during a routine clinic visit and can be used to safely and effectively deliver exenatide. Future studies of OKV-119, configured to release exenatide for a longer extended months-long duration, are warranted to determine whether the combination of metabolic improvements and beneficial weight-loss, coupled with minimal impact on pet-owner's lifestyle, lead to improved outcomes for obese cats and feline DM patients.
Abstract Background Mycophenolate is an immunomodulating agent successfully used for the treatment of moderate‐to‐severe atopic dermatitis (AD) in people. Mycophenolate is an effective steroid‐sparing treatment option for use in dogs with inflammatory skin diseases. Objective To evaluate whether once‐daily modified‐release mycophenolate (OKV‐1001) is safe and effective for treating moderate‐to‐severe canine AD. Animals Client‐owned atopic dogs ( n = 9) were enrolled. Materials and Methods In an open‐label multicentre pilot study, OKV‐1001 (30 mg/kg every 24 h) was given orally for ≤84 days. Concomitant tapering doses of glucocorticoids were administered up to Day (D)28. Clinicians assessed Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI‐04) on D0, D14, D28, D56 and D84. Body weight and clinical pathological parameters were measured at baseline and at the end of the study. Results Treatment with OKV‐1001 combined with glucocorticoids significantly reduced the severity of AD within two weeks in seven of nine (77.8%) dogs. The mean percentage change from baseline in the CADESI‐04 score was 29% ( p = 0.009) at D14 ( n = 9), 39% ( p = 0.008) at D28 ( n = 9) and 49% ( p = 0.03) at D56 ( n = 7) at which point glucocorticoids had been withdrawn. In two dogs the improvement in CADESI‐04 was 62% and 23% (respectively) on D84. No significant adverse events including clinical pathological findings were reported. Conclusions and Clinical Relevance Modified‐release mycophenolate (OKV‐1001) may represent a promising alternative treatment option for dogs with moderate‐to‐severe AD. The safety and efficacy profile of OKV‐1001 will need to be established in larger, placebo‐controlled clinical trials.
Objective Interindividual clinical response to leukotriene modifiers is highly variable, and less efficacious than inhaled corticosteroids in treating asthma. Genetic variability in 5-lipoxygenase biosynthetic and receptor pathway gene loci may influence cysteinyl-leukotriene production and subsequent response to leukotriene modifiers. Methods Using data from two clinical trials of 12-week duration, post-hoc analyses were performed in 174 patients randomized to montelukast. Associations between polymorphisms in 10 candidate genes (ALOX5, ALOX5AP, LTC4S, CYSLTR1, CYSLTR2, PLA2G4A, CYP2C9, CYP3A4, ADRB2, and NR3C1) and response to montelukast were modeled using change in morning peak expiratory flow and forced expiratory volume in 1 s (FEV1) to define the response phenotype. Results In our sample, eight out of 25 markers in 10 candidate genes were statistically associated with response to montelukast, with an estimated proportion of false discoveries of 16%. The strongest statistical evidence of clinically relevant pharmacogenetic effects peak expiratory flow were identified in CYSLTR2 (rs91227 and rs912278; P=0.02 and P=0.02, respectively) and ALOX5 (rs4987105 and rs4986832; P=0.01 and P=0.01, respectively). Patients with these variant genotypes, found in roughly 10–13% of patients, had an 18–25% improvement in peak expiratory flow. In contrast, the majority of patients with the wild-type alleles had only a marginal (8–10%) improvement. Conclusions The overall mean response to montelukast may be skewed towards a response phenotype by a small subset (<15%) of asthma patients. CYSLTR2 and ALOX5 polymorphisms may predispose a minority of individuals to excessive cysteinyl-leukotriene concentrations, yielding a distinct asthma phenotype most likely to respond to leukotriene modifier pharmacotherapy. These findings require replication to establish validity and clinical utility.
Abstract Beneficial weight-loss properties of glucagon-like peptide-1 receptor agonists (GLP-1RA) in obese people, with corresponding improvements in cardiometabolic risk factors, are well established. OKV-119 is an investigational drug delivery system that is being developed for the long-term delivery of the GLP-1RA exenatide to feline patients. The purpose of this study was to evaluate the drug release characteristics of subcutaneous OKV-119 implants configured to release exenatide for 84 days. Following a 7-day acclimation period, five purpose-bred cats were implanted with OKV-119 protypes and observed for a 112-day study period. Food intake, weekly plasma exenatide concentrations and body weight were measured. Exenatide plasma concentrations were detected at the first measured timepoint (Day 7) and maintained above baseline for over 84 Days. Over the first 28 days, reduced caloric intake and a reduction in body weight were observed in four of five cats. In these cats, a body weight reduction of at least 5% was maintained throughout the 112-day study period. This study demonstrates that a single OKV-119 implant can deliver the GLP-1RA exenatide for a months long duration. Results suggest that exposure to exenatide plasma concentrations ranging from 1.5 ng/ml to 4 ng/ml are sufficient for inducing weight loss in cats.
Summary Background Asthma is a clinically heterogeneous disease caused by a complex interaction between genetic susceptibility and diverse environmental factors. In common with other complex diseases the lack of a standardized scheme to evaluate the phenotypic variability poses challenges in identifying the contribution of genes and environments to disease expression. Objective To determine the minimum number of sets of features required to characterize subjects with asthma which will be useful in identifying important genetic and environmental contributors. Methods Probands aged 7–35 years with physician diagnosed asthma and symptomatic siblings were identified in 1022 nuclear families from 11 centres in six countries forming the Genetics of Asthma International Network. Factor analysis was used to identify distinct phenotypes from questionnaire, clinical, and laboratory data, including baseline pulmonary function, allergen skin prick test (SPT). Results Five distinct factors were identified:(1) baseline pulmonary function measures [forced expiratory volume in 1 s (FEV 1 ) and forced vital capacity (FVC)], (2) specific allergen sensitization by SPT, (3) self‐reported allergies, (4) symptoms characteristic of rhinitis and (5) symptoms characteristic of asthma. Replication in symptomatic siblings was consistent with shared genetic and/or environmental effects, and was robust across age groups, gender, and centres. Cronbach's α ranged from 0.719 to 0.983 suggesting acceptable internal scale consistencies. Derived scales were correlated with serum IgE, methacholine PC 20 , age and asthma severity (interrupted sleep). IgE correlated with all three atopy‐related factors, the strongest with the SPT factor whereas severity only correlated with baseline lung function, and with symptoms characteristic of rhinitis and of asthma. Conclusion In children and adolescents with established asthma, five distinct sets of correlated patient characteristics appear to represent important aspects of the disease. Factor scores as quantitative traits may be better phenotypes in epidemiological and genetic analyses than those categories derived from the presence or absence of combinations of +ve SPTs and/or elevated IgE.
Abstract Mycophenolic acid (MPA) is an immunomodulating agent commonly used in human medicine for the treatment of immune‐mediated diseases. There is growing evidence that the immunomodulating properties of mycophenolate mofetil (MMF), a prodrug of MPA, are therapeutically beneficial for the treatment of immune‐mediated diseases in dogs. A narrow therapeutic index and high inter‐and intra‐patient pharmacokinetic (PK) variability complicate the use of MMF. A better characterization of MPA pharmacokinetics is needed to help establish dosing regimens and standardized treatment protocols for canine patients. The purpose of this study was to evaluate the pharmacokinetics of MPA in dogs. MMF oral suspension (10 mg/kg) was administered to five healthy beagle dogs. Serial blood samples were collected from 0 to 18 hours after administration. The simultaneous quantification of MPA, and its metabolites MPA‐7‐O‐glucuronide (MPAG), and acyl glucuronide (AcMPAG) was determined by liquid chromatography (LC)‐mass spectrometry (MS)/MS. MPA peak concentrations were achieved rapidly (median Tmax of 0.5 h). Concentrations fell through 3 hours post‐dose and then plateaued around 20% of Cmax. The mean elimination half‐life was rapid (5.8 hours) and notable variability was observed in all PK parameters. The PK profiles for the MPAG and AcMPAG metabolites followed a similar pattern as MPA concentration. Future repeat‐dose studies will be needed to evaluate steady‐state PK parameters and to define therapeutic MPA dose levels.
Background: Mycophenolic acid (MPA) is a broad-acting immunomodulating agent that may be therapeutically beneficial for the treatment of immune-mediated diseases in canine patients. Objectives: To determine the suppressive effects of MPA on T-cell proliferation, and to assess the feasibility of a canine-specific q24 h modified-release MPA formulation (OKV-1001b). Animals: Fifteen healthy purpose-bred male beagle dogs. Methods: Two nearly identical open-label fifteen-day studies were conducted in which dogs were randomized to receive mycophenolate mofetil (MMF; 10 mg/kg q12h), or two doses of OKV-1001b (270 mg and 180 mg; q24h). Serial pharmacokinetic (PK) and pharmacodynamic (PD) samples were collected on Days 1, 8, and 15. MPA plasma concentrations were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), while an ex vivo T-cell proliferation assay assessed PD effects. Dogs were continuously monitored for evidence of side effects and gastrointestinal tolerability. Results: MPA induced inhibition of T-cell proliferation was observed following administration of all MPA preparations in a clear concentration-dependent manner. The PK/PD relationship was maintained across all days and time-points. Data generated herein suggest that MPA plasma concentrations above 600 ng/mL achieve at least 50% inhibition of T-cell proliferation. Conclusions and Clinical Importance: MPA holds therapeutic potential for treating dogs with immune-mediated disease, but clinical trials will be necessary to determine its safety and efficacy in naturally occurring disease. Likewise, q24h oral modified release MPA preparations that maintain MPA plasma concentrations between 600 and 1,000 ng/mL are warranted for further studies in client-owned dogs.
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