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Filgotinib, a preferential Janus Kinase‐1 inhibitor, is approved in Europe and Japan for treatment of rheumatoid arthritis and is being developed for treatment of other chronic inflammatory diseases. Three drug‐drug interactions studies were conducted in healthy subjects to evaluate the effect of P‐glycoprotein (P‐gp) modulation (study 1: P‐gp inhibition by itraconazole and study 2: P‐gp induction by rifampin) on filgotinib pharmacokinetics and the potential of filgotinib to impact exposure of metformin, an organic cation transporter (OCT) 2 and multidrug and toxin extrusion (MATE) 1/2K substrate (study 3). Co‐administration of filgotinib with itraconazole increased filgotinib exposure (maximum concentration [Cmax] by 64% and area under the curve to infinity [AUCinf] by 45%) but had no effect on the exposure of GS‐829845, filgotinib’s primary metabolite. Rifampin moderately reduced exposures of filgotinib and GS‐829845 (Cmax by 26% and AUCinf by 27% for filgotinib; Cmax by 19% and AUCinf by 38% for GS‐829845). The data confirmed that filgotinib is a P‐gp substrate. However, the magnitude of change in filgotinib/GS‐829845 exposure by P‐gp modulators is not deemed to be clinically relevant based on filgotinib exposure‐response analyses in subjects with rheumatoid arthritis. Filgotinib did not alter metformin exposures, indicating that filgotinib and GS‐829845 do not inhibit OCT2 and MATE1/2K at the clinical doses. Filgotinib was generally well‐tolerated when administered alone or with the co‐administered drugs in the studies. Results from these studies were the basis to enable the use of P‐gp modulators and substrates of OCT2, MATE1, and MATE2K with filgotinib without the need for dose modifications in the current approved rheumatoid arthritis population.

Tirabrutinib is an irreversible, small-molecule Bruton's tyrosine kinase (BTK) inhibitor, which was approved in Japan (VELEXBRU) to treat B-cell malignancies and is in clinical development for inflammatory diseases. As an application of model-informed drug development, a semimechanistic pharmacokinetic/pharmacodynamic (PK/PD) model for irreversible BTK inhibition of tirabrutinib was developed to support dose selection in clinical development, based on clinical PK and BTK occupancy data from two phase I studies with a wide range of PK exposures in healthy volunteers and in subjects with rheumatoid arthritis. The developed model adequately described and predicted the PK and PD data. Overall, the model-based simulation supported a total daily dose of at least 40 mg, either q.d. or b.i.d., with adequate BTK occupancy (> 90%) for further development in inflammatory diseases. Following the PK/PD modeling and simulation, the relationship between model-predicted BTK occupancy and preliminary clinical efficacy data was also explored and a positive trend was identified between the increasing time above adequate BTK occupancy and better efficacy in treatment for RA by linear regression.

For children under 12 years of age who have chronic hepatitis C virus (HCV) infection, there are currently no approved treatments with direct‐acting antiviral agents. We therefore evaluated the safety and efficacy of ledipasvir‐sofosbuvir in HCV‐infected children aged 3 to

Currently, the only approved hepatitis C virus (HCV) treatment for children aged

The global prevalence of ulcerative colitis is increasing, and induction and maintenance of remission is a crucial therapeutic goal. We assessed the efficacy and safety of filgotinib, a once-daily, oral Janus kinase 1 preferential inhibitor, for treatment of ulcerative colitis.This phase 2b/3, double-blind, randomised, placebo-controlled trial including two induction studies and one maintenance study was done in 341 study centres in 40 countries. Eligible patients were aged 18-75 years with moderately to severely active ulcerative colitis for at least 6 months before enrolment (induction study A: inadequate clinical response, loss of response to or intolerance to corticosteroids or immunosuppressants, naive to tumour necrosis factor [TNF] antagonists and vedolizumab [biologic-naive]; induction study B: inadequate clinical response, loss of response to or intolerance to any TNF antagonist or vedolizumab, no TNF antagonist or vedolizumab use within 8 weeks before screening [biologic-experienced]). Patients were randomly assigned 2:2:1 to receive oral filgotinib 200 mg, filgotinib 100 mg, or placebo once per day for 11 weeks. Patients who had either clinical remission or a Mayo Clinic Score response at week 10 in either induction study entered the maintenance study. Patients who received induction filgotinib were rerandomised 2:1 to continue their induction filgotinib regimen or to placebo. Patients who received induction placebo continued receiving placebo. The primary endpoint was clinical remission by Mayo endoscopic, rectal bleeding, and stool frequency subscores at weeks 10 and 58. For the induction studies, efficacy was assessed in all randomised patients who received at least one dose of study drug or placebo within that study. For the maintenance study, efficacy was assessed in all patients randomised to any filgotinib treatment group in the induction studies who received at least one dose of study drug or placebo in the maintenance study. Patients who received placebo throughout the induction and maintenance study were not included in the full analysis set for the maintenance study. Safety was assessed in all patients who received at least one dose of the study drug or placebo within each study. This trial is registered with ClinicalTrials.gov, NCT02914522.Between Nov 14, 2016, and March 31, 2020, we screened 2040 patients for eligibility. 659 patients enrolled in induction study A were randomly assigned to receive filgotinib 100 mg (n=277), filgotinib 200 mg (n=245), or placebo (n=137). 689 patients enrolled into induction study B were randomly assigned to receive filgotinib 100 mg (n=285), filgotinib 200 mg (n=262), or placebo (n=142). 34 patients in induction study A and 54 patients in induction study B discontinued the study drug before week 10. After efficacy assessment at week 10, 664 patients entered the maintenance study (391 from induction study A, 273 from induction study B). 93 patients continued to receive placebo. 270 patients who had received filgotinib 100 mg in the induction study were randomly assigned to receive filgotinib 100 mg (n=179) or placebo (n=91). 301 patients who had received filgotinib 200 mg in the induction study were randomly assigned to receive filgotinib 200 mg (n=202) or placebo (n=99). 263 patients discontinued treatment in the maintenance study. At week 10, a greater proportion of patients given filgotinib 200 mg had clinical remission than those given placebo (induction study A 26·1% vs 15·3%, difference 10·8%; 95% CI 2·1-19·5, p=0·0157; induction study B 11·5% vs 4·2%, 7·2%; 1·6-12·8, p=0·0103). At week 58, 37·2% of patients given filgotinib 200 mg had clinical remission versus 11·2% in the respective placebo group (difference 26·0%, 95% CI 16·0-35·9; p0·0001). Clinical remission was not significantly different between filgotinib 100 mg and placebo at week 10, but was significant by week 58 (23·8% vs 13·5%, 10·4%; 0·0-20·7, p=0·0420). The incidence of serious adverse events and adverse events of interest was similar between treatment groups. In the induction studies, serious adverse events occurred in 28 (5·0%) of 562 patients given filgotinib 100 mg, 22 (4·3%) of 507 patients given filgotinib 200 mg, and 13 (4·7%) of 279 patients given placebo. In the maintenance study, serious adverse events were reported in eight (4·5%) of 179 patients given filgotinib 100 mg, seven (7·7%) of 91 patients in the respective placebo group, nine (4·5%) of 202 patients in the filgotinib 200 mg group, and no patients in the respective placebo group. No deaths were reported during either induction study. Two patients died during the maintenance study; neither was related to treatment.Filgotinib 200 mg was well tolerated, and efficacious in inducing and maintaining clinical remission compared with placebo in patients with moderately to severely active ulcerative colitis.Gilead Sciences.

Physiologically-based pharmacokinetic (PBPK) modeling in predicting metabolic drug–drug interactions (mDDIs) is routinely used in drug development. Currently, the US FDA endorses the use of PBPK to potentially support dosing recommendations for investigational drugs as enzyme substrates of mDDIs, and to inform a lack of mDDIs for investigational drugs as enzyme modulators. We systematically evaluated the performance of PBPK modeling in predicting mDDIs published in the literature. Models developed to assess both investigational drugs as enzyme substrates (Groups 1 and 2, as being inhibited and induced, respectively) or enzyme modulators (Groups 3 and 4, as inhibitors and inducers, respectively) were evaluated. Predicted ratios of the area under the curve (AUCRs) and/or maximum plasma concentration (CmaxRs) with and without comedication were compared with the observed ratios. For Groups 1, 2, 3, and 4, 62, 50, 44, and 43% of model-predicted AUCRs, respectively, were within a predefined threshold of 1.25-fold of observed values (0.8–1.25x). When the threshold was widened to twofold, the values increased to 100, 80, 81, and 86% (0.5–2.0x). For Groups 3 and 4, prediction for mDDI liability (the existence or lack of mDDIs) using PBPK appears to be satisfactory. Our analysis supports the FDA’s current recommendations on the use of PBPK to predict mDDIs.

Background The melanin synthesis enzyme dopachrome tautomerase (Dct) regulates intracellular Ca 2+ in melanocytes. Homozygous Dct knockout (Dct −/− ) adult mice are vulnerable to atrial arrhythmias (AA). Objective The purpose of this study was to determine whether apamin-sensitive small conductance Ca 2+ -activated K + (SK) currents are upregulated in Dct −/− mice and contribute to AA. Methods Optical mapping was used to study the membrane potential of the right atrium in Langendorff perfused Dct −/− (n = 9) and Dct +/− (n = 9) mice. Results Apamin prolonged action potential duration (APD) by 18.8 ms (95% confidence interval [CI] 13.4–24.1 ms) in Dct −/− mice and by 11.5 ms (95% CI 5.4–17.6 ms) in Dct +/− mice at a pacing cycle length of 150 ms ( P = .047). The pacing cycle length threshold to induce APD alternans was 48 ms (95% CI 34–62 ms) for Dct −/− mice and 21 ms (95% CI 12–29 ms) for Dct +/− mice ( P = .002) at baseline, and it was 35 ms (95% CI 21–49 ms) for Dct −/− mice and 22 ms (95% CI 11–32 ms) for Dct +/− mice ( P = .025) after apamin administration. Apamin prolonged post-burst pacing APD by 8.9 ms (95% CI 3.9–14.0 ms) in Dct −/− mice and by 1.5 ms (95% CI 0.7–2.3 ms) in Dct +/− mice ( P = .005). Immunoblot and quantitative polymerase chain reaction analyses showed that protein and transcripts levels of SK1 and SK3 were increased in the right atrium of Dct −/− mice. AA inducibility (89% vs 11%; P = .003) and duration (281 seconds vs 66 seconds; P = .008) were greater in Dct −/− mice than in Dct +/− mice at baseline, but not different (22% vs 11%; P = 1.00) after apamin administration. Five of 8 (63%) induced atrial fibrillation episodes in Dct −/− mice had focal drivers. Conclusion Apamin-sensitive SK current upregulation in Dct −/− mice plays an important role in the mechanism of AA.

Background and Objectives Recent studies showed that, in addition to parasympathetic nerves, cervical vagal nerves contained significant sympathetic nerves. We hypothesized that cervical vagal nerve stimulation (VNS) may capture the sympathetic nerves within the vagal nerve and activate the stellate ganglion. Materials and Methods We recorded left stellate ganglion nerve activity (SGNA), left thoracic vagal nerve activity (VNA), and subcutaneous electrocardiogram in seven dogs during left cervical VNS with 30 seconds on-time and 30 seconds off time. We then compared the SGNA between VNS on and off times. Results Cervical VNS at moderate (0.75 mA) output induced large SGNA, elevated heart rate (HR), and reduced HR variability, suggesting sympathetic activation. Further increase of the VNS output to >1.5 mA increased SGNA but did not significantly increase the HR, suggesting simultaneous sympathetic and parasympathetic activation. The differences of integrated SGNA and integrated VNA between VNS on and off times (ΔSGNA) increased progressively from 5.2 mV-s {95% confidence interval (CI): 1.25-9.06, p=0.018, n=7} at 1.0 mA to 13.7 mV-s (CI: 5.97-21.43, p=0.005, n=7) at 1.5 mA. The difference in HR (ΔHR, bpm) between on and off times was 5.8 bpm (CI: 0.28-11.29, p=0.042, n=7) at 1.0 mA and 5.3 bpm (CI 1.92 to 12.61, p=0.122, n=7) at 1.5 mA. Conclusion Intermittent cervical VNS may selectively capture the sympathetic components of the vagal nerve and excite the stellate ganglion at moderate output. Increasing the output may result in simultaneously sympathetic and parasympathetic capture.

Background Purkinje cells ( PC s) are important in cardiac arrhythmogenesis. Whether small‐conductance calcium‐activated potassium ( SK ) channels are present in PC s remains unclear. We tested the hypotheses that subtype 2 SK ( SK 2) channel proteins and apamin‐sensitive SK currents are abundantly present in PC s. Methods and Results We studied 25 normal rabbit ventricles, including 13 patch‐clamp studies, 4 for Western blotting, and 8 for immunohistochemical staining. Transmembrane action potentials were recorded in current‐clamp mode using the perforated‐patch technique. For PC s, the apamin (100 nmol/L) significantly prolonged action potential duration measured to 80% repolarization by an average of 10.4 ms (95% CI , 0.11–20.72) (n=9, P =0.047). Voltage‐clamp study showed that apamin‐sensitive SK current density was significantly larger in PC s compared with ventricular myocytes at potentials ≥0 mV. Western blotting of SK 2 expression showed that the SK 2 protein expression in the midmyocardium was 58% ( P =0.028) and the epicardium was 50% ( P =0.018) of that in the pseudotendons. Immunostaining of SK 2 protein showed that PCs stained stronger than ventricular myocytes. Confocal microscope study showed SK 2 protein was distributed to the periphery of the PC s. Conclusions SK 2 proteins are more abundantly present in the PC s than in the ventricular myocytes of normal rabbit ventricles. Apamin‐sensitive SK current is important in ventricular repolarization of normal PC s.

Background A secondary rise of intracellular Ca2+(Cai) and an upregulation of apamin-sensitive K+current (IKAS) are characteristic findings of failing ventricular myocytes. We hypothesize that apamin, a specific IKASblocker, may induce torsades de pointes (TdP) ventricular arrhythmia from failing ventricles exhibiting secondary rises of Cai. Objective To test the hypothesis that small conductance Ca2+activated IKASmaintains repolarization reserve and prevents ventricular arrhythmia in a rabbit model of heart failure (HF). Methods We performed Langendorff perfusion and optical mapping studies in 7 hearts with pacing-induced HF and in 5 normal control rabbit hearts. Atrioventricular block was created by cryoablation to allow pacing at slow rates. Results The left ventricular ejection fraction reduced from 69.1% [95% confidence interval 62.3%-76.0%] before pacing to 30.4% [26.8%-34.0%] (N = 7; P

Small conductance calcium activated potassium (SK) currents are abundantly present in the neurons1, 2 and in atrial cardiomyocytes.3–6 However, little or no apamin-sensitive K currents are present in normal ventricles.3, 7, 8 These channels are activated by increases in intracellular Ca2+ (Cai) and are blocked by apamin.2 In the nervous system, activation of apamin-sensitive K+ current (IKAS) is responsible for slow afterhyperpolarizations, which help terminate neuronal action potential bursts.9 Similar to rapid neuronal discharges, ventricular fibrillation (VF) also causes Cai accumulation that may persist minutes after successful defibrillation.10 Cai accumulation and acute postshock action potential duration (APD) shortening facilitated the development of late phase 3 early afterdepolarization (EAD)11 (also known as Cai transient triggered firing)12, 13 and electrical storm in that model. The acute postshock APD shortening in failing ventricles was shown to be due to IKAS activation.8 A more recent study by Chang et al14 showed that both the IKAS and the SK protein are increased in the native hearts of transplant recipients, and that apamin significantly prolongs the APD in failing human ventricular myocytes but not in normal control ventricular myocytes. These findings suggest that IKAS is important in ventricular repolarization and arrhythmogenesis in failing ventricles by shortening APD during Cai accumulation. However, the ability to accelerate the repolarization may also be antiarrhythmic. The redundancy in the complexities of myocardial repolarization (repolarization reserve)15 is important in maintaining normal and orderly ventricular repolarization, while reduced repolarization reserve underlies the mechanisms of afterdepolarization and ventricular arrhythmias in congenital or acquired long-QT syndromes.16 Myocardial infarction (MI) is followed by significant arrhythmogenic ion-channel remodeling including downregulation of multiple K currents in the peri-infarct zone as well as in the subendocardial Purkinje fibers.17 These changes were thought to underlie the mechanisms of afterdepolarizations and ventricular arrhythmias in MI ventricles. While K current remodeling after MI has been extensively studied, none of these studies included an evaluation of IKAS after MI. If there is an increased IKAS, it would counterbalance the downregulation of other K currents, hence maintaining repolarization reserve. Inhibition of IKAS by apamin would prolong the APD and reduce the repolarization reserve. The purpose of the present study was to perform optical mapping studies and patch clamp studies to test the hypothesis that IKAS is increased in rabbit ventricles with chronic MI and contributes significantly to ventricular repolarization in MI ventricles.

Paralysis periodica paramyotonica is an overlapping disease that shares the features of paramyotonia characteristic of paramyotonia congenita (PC) and periodic paralysis characteristic of hyperkalemic periodic paralysis. We report the case of a 23-year-old man with paralysis periodica paramyotonica. His father and a younger brother also exhibited a similar phenotype. A SCN4A Arg1448Cys mutation was detected in this family. The affected family members exhibited marked shifts in compound muscle action potential amplitudes on exercise test, and muscle weakness could be induced by potassium loading and cold exposure. This case demonstrates that SCN4A Arg1448Cys can produce paralysis periodica paramyotonica. Other genetic or environmental factors may modulate the manifestation of SCN4A Arg1448Cys mutation.

Patients with CKD have an increased risk of cardiovascular mortality from arrhythmias and sudden cardiac death. We used a rat model of CKD (Cy/+) to study potential mechanisms of increased ventricular arrhythmias. Rats with CKD showed normal ejection fraction but hypertrophic myocardium. Premature ventricular complexes occurred more frequently in CKD rats than normal rats (42% versus 11%, P=0.18). By optical mapping techniques, action potential duration (APD) at 80% of repolarization was longer in CKD rats (78±4ms) than normal rats (63±3 ms, P

An 18-year-old woman presented with exercise induced sudden collapse. Series of cardiac work up revealed no structural cardiac abnormalities. Bidirectional ventricular tachycardia occurred during a treadmill exercise test. Under the impression of catecholaminergic polymorphic ventricular tachycardia, we screened the cardiac ryanodine receptor gene for mutation. We identified a novel heterozygous mutation at the 169th amino acid (Arg169Gln). This amino acid is highly conserved among many species and this mutation was not present in 50 normal control subjects. This patient was treated with a β-block with good response.

Background— Apamin-sensitive K currents ( I KAS ) are upregulated in heart failure. We hypothesize that apamin can flatten action potential duration restitution (APDR) curve and can reduce ventricular fibrillation duration in failing ventricles. Methods and Results— We simultaneously mapped membrane potential and intracellular Ca (Ca i ) in 7 rabbit hearts with pacing-induced heart failure and in 7 normal hearts. A dynamic pacing protocol was used to determine APDR at baseline and after apamin (100 nmol/L) infusion. Apamin did not change APD 80 in normal ventricles, but prolonged APD 80 in failing ventricles at either long (≥300 ms) or short (≤170 ms) pacing cycle length, but not at intermediate pacing cycle length. The maximal slope of APDR curve was 2.03 (95% confidence interval, 1.73–2.32) in failing ventricles and 1.26 (95% confidence interval, 1.13–1.40) in normal ventricles at baseline ( P =0.002). After apamin administration, the maximal slope of APDR in failing ventricles decreased to 1.43 (95% confidence interval, 1.01–1.84; P =0.018), whereas no significant changes were observed in normal ventricles. During ventricular fibrillation in failing ventricles, the number of phase singularities (baseline versus apamin, 4.0 versus 2.5), dominant frequency (13.0 versus 10.0 Hz), and ventricular fibrillation duration (160 versus 80 s) were all significantly ( P Conclusions— Apamin prolongs APD at long and short, but not at intermediate pacing cycle length in failing ventricles. I KAS upregulation may be antiarrhythmic by preserving the repolarization reserve at slow heart rate, but is proarrhythmic by steepening the slope of APDR curve, which promotes the generation and maintenance of ventricular fibrillation.

Na channel blockers are effective in suppressing delayed afterdepolarizations (DADs) in isolated Purkinje fibers. However, in isolated mouse ventricular myocytes lacking calsequestrin, only those Na channel blockers that also inhibit type 2 ryanodine receptor channels were effective against spontaneous Ca elevation (SCaE) and DADs.To test the hypothesis that combined Na channel and type 2 ryanodine receptor channel blocker ((R)-propafenone) is more effective than a Na channel blocker (lidocaine) in suppressing SCaE and DADs in the intact rabbit ventricles.We compared (R)-propafenone (3 μmol/L) with lidocaine (50 μmol/L) on SCaE and DADs by using epicardial optical mapping of intracellular calcium (Ca(i)) and membrane voltage in Langendorff-perfused rabbit hearts. SCaE and DADs were induced by rapid pacing trains and isoproterenol (0.3 μmol/L) infusion. One arbitrary unit is equivalent to the Ca transient amplitude of paced beats.SCaEs were observed at the cessation of rapid pacing in all hearts at baseline. (R)-Propafenone nearly completely inhibited DADs and SCaE (0.04 arbitrary units [95% confidence interval 0.02-0.06] vs 0.23 arbitrary units [95% confidence interval 0.18-0.28] at baseline; n = 6 hearts; P.001). Lidocaine also significantly reduced the SCaE but was significantly (P.05) less effective than (R)-propafenone. Both drugs increased the rise time of action potential upstroke and reduced conduction velocity to a similar extent, suggesting a significant inhibition of I(Na).Both Na channel blockers significantly reduced tachycardia-induced SCaEs in the rabbit ventricles, but (R)-propafenone was significantly more effective than lidocaine. These data suggest that type 2 ryanodine receptor inhibition potentiates the activity of Na channel blockers against SCaE and DADs in the intact hearts.

Background/Purpose Desmosome gene mutations have been reported in patients with arrhythmogenic right ventricular dysplasia (ARVD). However, there are hardly any genetic studies in Asians. We studied the clinical characteristics, cardiac manifestations and desmosome gene mutations in ARVD patients in Taiwan. Methods Medical records of five ARVD patients were reviewed and genomic DNA was obtained from peripheral blood samples. Mutation screening in desmoplakin (DSP), plakophilin-2, desmoglein-2 (DSG2) and desmocollin-2 genes was performed using polymerase chain reaction and DNA sequencing techniques. Results Among the five patients, three presented with palpitations followed by loss of consciousness, and the other two had palpitations or chest tightness without loss of consciousness. Electrocardiogram (ECG), magnetic resonance imaging and signal averaged ECG results were similar to those reported in Western countries. Mutations in the desmosome genes were identified in four of the five patients (three with a DSG2 mutation and one with a DSP mutation). Five gene mutations were noted in four patients and all mutations were novel (one patient had a DSG2 double mutation). The mutation types were missense in four and splicing mutation in one. Conclusion Patients with ARVD in Taiwan had similar clinical and cardiac manifestations as reported in the Western literature. More than half of the patients had desmosome gene mutations.

Metformin has been reported to reduce cardiovascular complications in diabetic patients. The purpose of the present study was to investigate the anti-inflammatory effects of metformin on endothelial cells and the related molecular mechanisms.Human umbilical vein endothelial cells (HUVEC) were used for the experiments. The effects of metformin on TNF-alpha-induced IL-6 production were investigated. Modulation of AMPK and related signal transduction pathways were also performed.TNF-alpha increased IL-6 secretion by HUVEC in a dose-dependent manner but inhibitors of NF-kappaB abolished the TNF-alpha-induced IL-6 production. Pre-treatment with metformin (100-1000 micromol/L) also inhibited TNF-alpha-induced IL-6 production, phosphorylation of IkappaB kinase (IKK) alpha/beta and IkappaB-alpha degradation. Metformin increased phosphorylation of AMP-activated kinase (AMPK) but wortmannin, a PI3K inhibitor, negated its effects on AMPK phosphorylation and TNF-alpha-induced IkappaB-alpha degradation. AICAR, a direct AMPK activator, had inhibitory effects on TNF-alpha-induced IL-6 production, similar to that of metformin. Transfection of siRNA against alpha1-AMPK eradicated the inhibitory effects of metformin on TNF-alpha-induced IL-6, implying the essential role of AMPK.Metformin had anti-inflammatory effects on endothelial cells and inhibited TNF-alpha-induced IKKalpha/beta phosphorylation, IkappaB-alpha degradation and IL-6 production in HUVEC. This effect was related to PI3K-dependent AMPK phosphorylation.