Update on the evaluation of a new drug for effects on cardiac repolarization in humans: issues in early drug development

ToxSTK: A multi-target toxicity assessment utilizing molecular structure and stacking ensemble learning

Drug registration requires risk assessment of new active pharmaceutical ingredients or excipients to ensure they are safe for human health and the environment. However, traditional risk assessment is expensive and relies heavily on animal testing. Machine learning (ML) has been used as a risk assessment tool, providing less time, money, and involved animals than in vivo experiments. Despite that, the ML models often rely on a single model, which may introduce bias and unreliable prediction. Stacking ensemble learning is an ML framework that makes predictions based on multimodal outcomes. This framework performs well in quantitative structure-activity relationship (QSAR) studies. In this study, we developed ToxSTK, a multi-target toxicity assessment using stacking ensemble learning. We aimed to create an ML tool that facilitates toxicity assessments more affordably with reduced reliance on animal models. We focused on four key targets generally assessed in early-stage drug development: hERG toxicity, mTOR toxicity, PBMCs toxicity, and mutagenicity. Our model integrated 12 molecular fingerprints with 3 ML algorithms, generating 36 novel predictive features (PFs). These PFs were then combined to construct the final meta-decision model. Our results demonstrated that the ToxSTK model surpasses standard regression and classification metrics, ensuring it is highly reliable and accurate in predicting chemical toxicities within its application domain. This model passed the y-randomization test, confirming that the identified QSAR is robust and not due to random chance. Additionally, this model outperforms the existing ML methods for these endpoints, suggesting its effectiveness for risk assessment applications. We recommend incorporating this stacking ensemble learning framework into the chemical risk assessment pipeline to improve model generalization, accuracy, robustness, and reliability.

Case report: Phosphoinositide 3-kinase inhibitor with fulvestrant in a patient with ER+/HER2- metastatic breast carcinoma induced fatal arrhythmias: a preventable event?

Phosphoinositide 3-kinase (PI3K) inhibitors have shown synergistic anticancer effects with endocrine therapy against ER+/PIK3CA-mutated breast cancer. PI3K inhibitors for cancer therapy are becoming more common. There is an increasing need to understand their cardiac adverse events. In this report, we describe the features of near-fatal mixed arrhythmias in a patient who was undergoing a phase Ib clinical study of PI3Kα inhibitor with fulvestrant. Subsequently, the patient survived by cardiopulmonary resuscitation and therefore did not die. This case highlights that PI3K inhibitors can induce QT/QTc prolongation and predispose patients to TdP. The combination of QT/QTc prolongation in combination with prolonged cardiac repolarization, such as an AV block during treatment with PI3Kα inhibitor, may aggravate the occurrence of TdP. It is likely to be a safer strategy to adjust the standard of discontinuing drugs and continuing drugs (QTc interval was <500 and <60 ms at baseline) or choose other types of alternative treatment options. This report provided some ideas for clinicians to identify early and prevent the occurrence of fatal arrhythmias during anticancer treatment.

Association of Torsade de Pointes and QT Prolongation With Antifungal Triazoles: Analysis Using a Pharmacovigilance Database

BACKGROUND/AIM

Torsade de pointes (TdP)/QT prolongation (QTP) is one of the most life-threatening adverse effects of antifungal triazoles. The aim of the present study was to evaluate the association of antifungal triazoles with TdP/QTP by age group and the profile of the time of TdP/QTP onset by analyzing the spontaneous adverse event database for Japan.

PATIENTS AND METHODS

Data registered in the Japanese Adverse Drug Event Report database (JADER) from April 2004 to March 2022 were analyzed. The association between the administration of antifungal triazoles and TdP/QTP according to age was evaluated using an adjusted reporting odds ratio (aROR). In addition, the time-to-onset of TdP/QTP after antifungal triazole treatment was analyzed using the Weibull distribution according to the route of administration.

RESULTS

Antifungal triazole treatment was associated with TdP/QTP (aROR=1.77, 95% confidence interval=1.52-2.07). In the subgroup analyses by age group, antifungal triazole treatments in patients ≤29 years old and ≥50 (except ≥90) years old were associated with TdP/QTP. The medians (quartiles) of time-to-onset for intravenous and oral antifungal triazole treatment were 8 (6-12) and 23 (8-86) days, respectively. In addition, the shape parameter in the Weibull distribution analysis of oral triazole treatment revealed that the hazard exhibited an early failure profile.

CONCLUSION

TdP/QTP is associated with antifungal triazoles even in young patients, and patients should be monitored for the development of TdP/QTP, especially early after the initiation of treatment.

Characterizing complex and competing drug-drug interactions between the antiviral regimen of glecaprevir and pibrentasvir with rifampin or carbamazepine

The fixed-dose combination of the direct acting antivirals glecaprevir (GLE) and pibrentasvir (PIB) is an oral, once-daily treatment for all six major genotypes of chronic hepatitis C virus infection. A single and multiple-dose rifampin study (N = 12) and a carbamazepine study (N = 12) were conducted in healthy subjects to evaluate the effects of CYP3A/P-gp induction and OATP inhibition on the pharmacokinetics of GLE and PIB. In study 1, GLE 300 mg + PIB 120 mg was administered as a single dose either alone, after single and multiple daily doses of rifampin 600 mg, or 24 h after the last rifampin dose. In study 2, GLE 300 mg + PIB 120 mg was administered as a single dose either alone or after multiple doses of carbamazepine 200 mg. Relative to GLE + PIB alone, exposure of GLE was significantly increased by the first co-administered rifampin dose due to OATP inhibition, significantly decreased 24 h after the last rifampin dose due to CYP3A/P-gp induction, and slightly increased when co-administered with steady-state rifampin due to a combination of inhibition and induction forces. Exposure of PIB was not affected when co-administered with the first rifampin dose but was significantly decreased with steady-state rifampin co-administration, or 24 h after the last rifampin dose due to P-gp induction. Carbamazepine significantly decreased GLE and PIB exposure, mainly attributed to P-gp induction. The regimens tested were generally well-tolerated by the subjects and no new safety issues were identified.

QTc Interval Reference Values and Their (Non)-Maturational Factors in Neonates and Infants: A Systematic Review

QTc interval measurement is a widely used screening tool to assess the risk of cardiac diseases, arrhythmias, and is a useful biomarker for pharmacovigilance. However, the interpretation of QTc is difficult in neonates due to hemodynamic maturational changes and uncertainties on reference values. To describe trends in QTc values throughout infancy (1 year of life), and to explore the impact of (non)-maturational changes and medicines exposure, a structured systematic review (PROSPERO CRD42022302296) was performed. In term neonates, a decrease was observed over the first week of life, whereafter values increased until two months of age, followed by a progressive decrease until six months. A similar pattern with longer QTc values was observed in preterms. QTc is influenced by cord clamping, hemodynamic changes, therapeutic hypothermia, illnesses and sleep, not by sex. Cisapride, domperidone and doxapram result in QTc prolongation in neonates. Further research in this age category is needed to improve primary screening practices and QTcthresholds, earlier detection of risk factors and precision pharmacovigilance.

Exposure-response analysis of adverse events associated with molibresib and its active metabolites in patients with solid tumors

Molibresib (GSK525762) is an investigational orally bioavailable small-molecule bromodomain and extraterminal (BET) protein inhibitor for the treatment of advanced solid tumors. In the first-time-in-human BET115521 study of molibresib in patients with solid tumors, thrombocytopenia was the most frequent treatment-related adverse event (AE), QT prolongation was an AE of special interest based on preclinical signals, and gastrointestinal (GI) AEs (nausea, vomiting, diarrhea, and dysgeusia) were often observed. The aims of this analysis were the following: (i) develop a population pharmacokinetic (PK)/pharmacodynamic (PD) model capable of predicting platelet time courses in individual patients after administration of molibresib and identify covariates of clinical interest; (ii) evaluate the effects of molibresib (and/or its two active metabolites [GSK3529246]) exposure on cardiac repolarization by applying a systematic modeling approach using high-quality, intensive, PK time-matched 12-lead electrocardiogram measurements; (iii) evaluate the exposure-response (ER) relationship between molibresib and/or GSK3529246 exposures and the occurrence of Grade 2 or higher GI AEs. Overall, the PK/PD model (including a maximal drug effect model and molibresib concentration) adequately described platelet counts following molibresib treatment and was used to simulate the impact of molibresib dosing on thrombocytopenia at different doses and regimens. ER analyses showed no clinically meaningful QT interval prolongation with molibresib at up to 100 mg q.d., and no strong correlation between molibresib exposure and the occurrence of Grade 2 or higher GI AEs. The models described here can aid dosing/schedule and drug combination strategies and may support a thorough QT study waiver request for molibresib.

Comparing the consistency of electrocardiogram interval measurements by resting ECG versus 12-lead Holter

In clinical trials, traditionally only a limited number of 12-lead resting electrocardiograms (ECGs) can be recorded and, thus, long intervals may elapse between assessment timepoints and valuable information may be missed during times when patients' cardiac electrical activity is not being monitored. These limitations have led to the increasing use of Holter recorders which provide continuous data registrations while reducing the burden on patients and freeing up time for clinical trial staff to perform other tasks. However, there is a shortage of data comparing the two approaches. In this study, data from a randomized, double-blind, four-period, crossover thorough QT study in 40 healthy subjects were used to compare continuous 12-lead Holter recordings to standard 12-lead resting ECGs which were recorded in parallel. Heart rate and QT interval data were estimated by averaging three consecutive heartbeats. Values exceeding the sample average by more than 5% were tagged as outliers and excluded from the analysis. Visual comparisons of the ECG waveforms of the Holter signal showed a good correlation with resting ECGs at matching timepoints. Resting ECG data revealed sex differences that Holter data did not show. Specifically, women were found to have a longer QTcF of 20 ms, while men had a lower heart rate. We found that continuous recordings provided a more accurate reflection of changes in cardiac electrical activity over 24 hr. However, manual adjudication is still required to ensure the quality and accuracy of ECG data, and that only artifacts are removed thereby avoiding loss of true signals.

Evaluation of the Potential Effect of Iptakalim Hydrochloride on the QT Interval in Single- and Multiple-Ascending-Dose Studies Using Concentration-QTc Analysis

Cardiotoxicity has been one of the most common causes of withdrawal of drugs from the market, and prolongation of the QT interval is one of the manifestations of drug cardiotoxicity. Iptakalim hydrochloride (ITKL) is a selective ATP-sensitive potassium channel opener used to treat hypertension. It is crucial to assess the risk of cardiac repolarization of ITKL in clinical trials. This study was conducted to determine the effect of ITKL on corrected QT (QTc) interval. A randomized, double-blind, placebo-controlled single- and multidose regimen was carried out to investigate the QTc and ITKL concentration correlation. ITKL was administered at doses of 5, 10, 15, and 20 mg with single oral administration and 10 and 20 mg with multiple oral administration, along with placebo, in 83 healthy subjects. Electrocardiograms (ECGs) and blood samples were collected on a preset time schedule. A ΔΔQTcF effect above 10 milliseconds was excluded at all observed plasma levels. Among them, the highest dose was 20 mg, which is twice the therapeutic dose. We concluded that ITKL did not prolong the QT interval in healthy subjects within the therapeutic dose. Retrospectively registered: The study was registered at Chinese Clinical Trial Registry with registration number ChiCTR1800014466.

Management of Adverse Events Associated with Cabozantinib Treatment in Patients with Advanced Hepatocellular Carcinoma

Cabozantinib is an oral multikinase inhibitor whose targets include vascular endothelial growth factor receptors, MET, and the TAM family of kinases (TYRO3, AXL, MER). Cabozantinib is approved for patients with advanced hepatocellular carcinoma who have been previously treated with sorafenib, based on improved overall survival and progression-free survival relative to placebo in the phase III CELESTIAL study. During CELESTIAL, the most common adverse events (AEs) experienced by patients receiving cabozantinib included palmar-plantar erythrodysesthesia, fatigue, gastrointestinal-related events, and hypertension. These AEs can significantly impact treatment tolerability and patient quality of life. However, AEs can be effectively managed with supportive care and dose modifications. During CELESTIAL, more than half of the patients receiving cabozantinib required a dose reduction, while the rate of treatment discontinuation due to AEs was low. Here, we review the safety profile of cabozantinib and provide guidance on the prevention and management of the more common AEs, based on current evidence from the literature as well as our clinical experience. We consider the specific challenges faced by clinicians in treating this patient population and discuss factors that may affect exposure and tolerability to cabozantinib.

Evaluation of the Effect of Contezolid (MRX-I) on the Corrected QT Interval in a Randomized, Double-Blind, Placebo- and Positive-Controlled Crossover Study in Healthy Chinese Volunteers

Contezolid (MRX-I), a new oxazolidinone, is an antibiotic in development for treating complicated skin and soft tissue infections caused by resistant Gram-positive bacteria. This was a thorough QT study conducted in 52 healthy subjects who were administered oral contezolid at a therapeutic (800 mg) dose, a supratherapeutic (1,600 mg) dose, placebo, and oral moxifloxacin at 400 mg in four separate treatment periods. The pharmacokinetic profile of contezolid was also evaluated. Time point analysis indicated that the upper bounds of the two-sided 90% confidence interval (CI) for placebo-corrected change-from-baseline QTc (ΔΔQTc) were <10 ms for the contezolid therapeutic dose at each time point. The upper bound of the 90% CI for ΔΔQTc was slightly more than 10 ms with the contezolid supratherapeutic dose at 3 and 4 h postdose, and the prolongation effect on the QT/QTc interval was less than that of the positive control, moxifloxacin, at 400 mg. At 3 and 4 h after the moxifloxacin dose, the moxifloxacin group met the assay sensitivity criteria outlined in ICH Guidance E14 by having a lower confidence bound of ≥5 ms. The results of a linear exposure-response model which were similar to that of a time point analysis demonstrated a slightly positive relationship between contezolid plasma levels and ΔQTcF interval with a slope of 0.227 ms per mg/liter (90% CI, 0.188 to 0.266). In summary, contezolid did not prolong the QT interval at a therapeutic dose and may have a slight effect on QT interval prolongation at a supratherapeutic dose.

Combining an in silico proarrhythmic risk assay with a tPKPD model to predict QTc interval prolongation in the anesthetized guinea pig assay

Human-based in silico models are emerging as important tools to study the effects of integrating inward and outward ion channel currents to predict clinical proarrhythmic risk. The aims of this study were 2-fold: 1) Evaluate the capacity of an in silico model to predict QTc interval prolongation in the in vivo anesthetized cardiovascular guinea pig (CVGP) assay for new chemical entities (NCEs) and; 2) Determine if a translational pharmacokinetic/pharmacodynamic (tPKPD) model can improve the predictive capacity. In silico simulations for NCEs were performed using a population of human ventricular action potential (AP) models. PatchXpress® (PX) or high throughput screening (HTS) ion channel data from respectively n = 73 and n = 51 NCEs were used as inputs for the in silico population. These NCEs were also tested in the CVGP (n = 73). An M5 pruned decision tree-based regression tPKPD model was used to evaluate the concentration at which an NCE is liable to prolong the QTc interval in the CVGP. In silico results successfully predicted the QTc interval prolongation outcome observed in the CVGP with an accuracy/specificity of 85%/73% and 75%/77%, when using PX and HTS ion channel data, respectively. Considering the tPKPD predicted concentration resulting in QTc prolongation (EC_5%) increased accuracy/specificity to 97%/95% using PX and 88%/97% when using HTS. Our results support that human-based in silico simulations in combination with tPKPD modeling can provide correlative results with a commonly used early in vivo safety assay, suggesting a path toward more rapid NCE assessment with reduced resources, cycle time, and animal use.

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Cardiac electrophysiological in silico model predicts QTc interval prolongation in the guinea pig.

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PKPD model predicts relevant QTc interval prolongation concentration in guinea pig.

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Combining the models improves the accuracy of predicting guinea pig QTc effects.

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Combining models accelerates assessment of QTc with lower resources and animal use.

Changes in left ventricular repolarization after short-term testosterone replacement therapy in hypogonadal males

BACKGROUND AND AIM

Evidences suggest that androgen deficiency is associated with sudden cardiac death (SCD). Our purpose was to analyse some electrocardiographic (ECG) markers of repolarization phase in hypogonadal patients either at baseline or after testosterone replacement therapy (TRT).

PATIENTS AND METHODS

Baseline and after 6 months of testosterone replacement therapy, 14 hypogonadal patients and 10 age-matched controls underwent a short-term ECG recordings at rest and immediately after a maximal exercise test. The following ECG parameters have been collected: QTe (the interval between the q wave the end of T wave), QTp (the interval between the q wave and the peak of T wave), and Te (the interval between the peak and the end of T wave).

RESULTS

At baseline, in the hypogonadal patients, corrected QTe and QTp values were longer at rest than in the controls at rest (p < 0.05), whereas, during the recovery phase, only the QTp remained significantly longer (p < 0.05). After TRT, hypogonadal patients showed an improvement only in Te (p < 0.05). Conversely, any difference between hypogonadal patients and control subjects was found with respect to the markers of temporal dispersion of repolarization phases, except for a worse QTp → Te coherence (p = 0.001) obtained during the recovery phase.

CONCLUSIONS

In conclusion, at rest, hypogonadal patients suffer from a stable increase in the myocardial repolarization phase without an increase in its temporal dispersion and, hence, the SCD risk seems to be low.

LUF7244, an allosteric modulator/activator of Kv 11.1 channels, counteracts dofetilide-induced torsades de pointes arrhythmia in the chronic atrioventricular block dog model

BACKGROUND AND PURPOSE

K_v 11.1 (hERG) channel blockade is an adverse effect of many drugs and lead compounds, associated with lethal cardiac arrhythmias. LUF7244 is a negative allosteric modulator/activator of K_v 11.1 channels that inhibits early afterdepolarizations in vitro. We tested LUF7244 for antiarrhythmic efficacy and potential proarrhythmia in a dog model.

EXPERIMENTAL APPROACH

LUF7244 was tested in vitro for (a) increasing human I_Kv11.1 and canine I_Kr and (b) decreasing dofetilide-induced action potential lengthening and early afterdepolarizations in cardiomyocytes derived from human induced pluripotent stem cells and canine isolated ventricular cardiomyocytes. In vivo, LUF7244 was given intravenously to anaesthetized dogs in sinus rhythm or with chronic atrioventricular block.

KEY RESULTS

LUF7244 (0.5-10 μM) concentration dependently increased I_Kv11.1 by inhibiting inactivation. In vitro, LUF7244 (10 μM) had no effects on I_KIR2.1 , I_Nav1.5 , I_Ca-L , and I_Ks , doubled I_Kr , shortened human and canine action potential duration by approximately 50%, and inhibited dofetilide-induced early afterdepolarizations. LUF7244 (2.5 mg·kg^-1 ·15 min^-1 ) in dogs with sinus rhythm was not proarrhythmic and shortened, non-significantly, repolarization parameters (QTc: -6.8%). In dogs with chronic atrioventricular block, LUF7244 prevented dofetilide-induced torsades de pointes arrhythmias in 5/7 animals without normalization of the QTc. Peak LUF7244 plasma levels were 1.75 ± 0.80 during sinus rhythm and 2.34 ± 1.57 μM after chronic atrioventricular block.

CONCLUSIONS AND IMPLICATIONS

LUF7244 counteracted dofetilide-induced early afterdepolarizations in vitro and torsades de pointes in vivo. Allosteric modulators/activators of K_v 11.1 channels might neutralize adverse cardiac effects of existing drugs and newly developed compounds that display QTc lengthening.

Grapefruit juice prolongs the QT interval of healthy volunteers and patients with long QT syndrome

BACKGROUND

The list of medications linked to drug-induced long QT syndrome (LQTS) is diverse. It is possible that food products too have QT-prolonging potential.

OBJECTIVE

We tested the effects of grapefruit juice on the QT interval with the methodology used by the pharmaceutical industry to test new drugs.

METHODS

This was an open-label, randomized, crossover study with blinded outcome evaluation, a thorough QT study of grapefruit juice performed according to the Guidelines for the Clinical Evaluation of QT/QTc for Non-antiarrhythmic Drugs. Thirty healthy volunteers and 10 patients with congenital LQTS were studied. Healthy volunteers drank 2 L of grapefruit juice (in divided doses), or received 400 mg oral moxifloxacin, in a randomized crossover study. Patients with LQTS were tested with only grapefruit. Repeated baseline, off-drug, and on-drug (grapefruit or moxifloxacin) electrocardiograms were scanned and coded. QT measurements were done with electronic calipers.

RESULTS

In comparison to off-drug electrocardiograms, grapefruit juice led to significant rate-corrected QT (QTc) prolongation. The absolute net QTc prolongation from grapefruit was 14.0 ms (95% confidence interval 6.2-21.7 ms; P < .001). The QT-prolonging effects of grapefruit in healthy volunteers were comparable with those of moxifloxacin. The QT-prolonging effects of grapefruit juice were greater in female patients and particularly marked in patients with LQTS (net QTc prolongation 21.8 ms; 95% confidence interval 3.4-35.3 ms; P = .034).

CONCLUSION

Grapefruit juice, at doses tested, prolongs the QT interval. The effect is significant in healthy volunteers, greater in female patients, and more so in patients with LQTS.

Can non-clinical repolarization assays predict the results of clinical thorough QT studies? Results from a research consortium

Background and Purpose

Translation of non‐clinical markers of delayed ventricular repolarization to clinical prolongation of the QT interval corrected for heart rate (QTc) (a biomarker for torsades de pointes proarrhythmia) remains an issue in drug discovery and regulatory evaluations. We retrospectively analysed 150 drug applications in a US Food and Drug Administration database to determine the utility of established non‐clinical in vitro IKr current human ether‐à‐go‐go‐related gene (hERG), action potential duration (APD) and in vivo (QTc) repolarization assays to detect and predict clinical QTc prolongation.

Experimental Approach

The predictive performance of three non‐clinical assays was compared with clinical thorough QT study outcomes based on free clinical plasma drug concentrations using sensitivity and specificity, receiver operating characteristic (ROC) curves, positive (PPVs) and negative predictive values (NPVs) and likelihood ratios (LRs).

Key Results

Non‐clinical assays demonstrated robust specificity (high true negative rate) but poor sensitivity (low true positive rate) for clinical QTc prolongation at low‐intermediate (1×–30×) clinical exposure multiples. The QTc assay provided the most robust PPVs and NPVs (ability to predict clinical QTc prolongation). ROC curves (overall test accuracy) and LRs (ability to influence post‐test probabilities) demonstrated overall marginal performance for hERG and QTc assays (best at 30× exposures), while the APD assay demonstrated minimal value.

Conclusions and Implications

The predictive value of hERG, APD and QTc assays varies, with drug concentrations strongly affecting translational performance. While useful in guiding preclinical candidates without clinical QT prolongation, hERG and QTc repolarization assays provide greater value compared with the APD assay.

Reduced cardiotoxicity and increased oral efficacy of artemether polymeric nanocapsules in Plasmodium berghei-infected mice

Artemether (ATM) cardiotoxicity, its short half-life and low oral bioavailability are the major limiting factors for its use to treat malaria. The purposes of this work were to study free-ATM and ATM-loaded poly-ε-caprolactone nanocapules (ATM-NC) cardiotoxicity and oral efficacy on Plasmodium berghei-infected mice. ATM-NC was obtained by interfacial polymer deposition and ATM was associated with polymeric NC oily core. For cardiotoxicity evaluation, male black C57BL6 uninfected or P. berghei-infected mice received, by oral route twice daily/4 days, vehicle (sorbitol/carboxymethylcellulose), blank-NC, free-ATM or ATM-NC at doses 40, 80 or 120 mg kg-1. Electrocardiogram (ECG) lead II signal was obtained before and after treatment. For ATM efficacy evaluation, female P. berghei-infected mice were treated the same way. ATM-NC improved antimalarial in vivo efficacy and reduced mice mortality. Free-ATM induced significantly QT and QTc intervals prolongation. ATM-NC (120 mg kg-1) given to uninfected mice reduced QT and QTc intervals prolongation 34 and 30%, respectively, compared with free-ATM. ATM-NC given to infected mice also reduced QT and QTc intervals prolongation, 28 and 27%, respectively. For the first time, the study showed a nanocarrier reducing cardiotoxicity of ATM given by oral route and it was more effective against P. berghei than free-ATM as monotherapy.

Preclinical study of a Kv11.1 potassium channel activator as antineoplastic approach for breast cancer

Potassium ion (K⁺) channels have been recently found to play a critical role in cancer biology. Despite that pharmacologic manipulation of ion channels is recognized as an important therapeutic approach, very little is known about the effects of targeting of K⁺ channels in cancer. In this study, we demonstrate that use of the Kv11.1 K⁺ channel activator NS1643 inhibits tumor growth in an in vivo model of breast cancer.

Tumors exposed to NS1643 had reduced levels of proliferation markers, high expression levels of senescence markers, increased production of ROS and DNA damage compared to tumors of untreated mice. Importantly, mice treated with NS1643 did not exhibit significant cardiac dysfunction. In conclusion, pharmacological stimulation of Kv11.1 activity produced arrested TNBC-derived tumor growth by generating DNA damage and senescence without significant side effects. We propose that use of Kv11.1 channels activators could be considered as a possible pharmacological strategy against breast tumors.

Human In Silico Drug Trials Demonstrate Higher Accuracy than Animal Models in Predicting Clinical Pro-Arrhythmic Cardiotoxicity

Early prediction of cardiotoxicity is critical for drug development. Current animal models raise ethical and translational questions, and have limited accuracy in clinical risk prediction. Human-based computer models constitute a fast, cheap and potentially effective alternative to experimental assays, also facilitating translation to human. Key challenges include consideration of inter-cellular variability in drug responses and integration of computational and experimental methods in safety pharmacology. Our aim is to evaluate the ability of in silico drug trials in populations of human action potential (AP) models to predict clinical risk of drug-induced arrhythmias based on ion channel information, and to compare simulation results against experimental assays commonly used for drug testing. A control population of 1,213 human ventricular AP models in agreement with experimental recordings was constructed. In silico drug trials were performed for 62 reference compounds at multiple concentrations, using pore-block drug models (IC₅₀/Hill coefficient). Drug-induced changes in AP biomarkers were quantified, together with occurrence of repolarization/depolarization abnormalities. Simulation results were used to predict clinical risk based on reports of Torsade de Pointes arrhythmias, and further evaluated in a subset of compounds through comparison with electrocardiograms from rabbit wedge preparations and Ca²⁺-transient recordings in human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs). Drug-induced changes in silico vary in magnitude depending on the specific ionic profile of each model in the population, thus allowing to identify cell sub-populations at higher risk of developing abnormal AP phenotypes. Models with low repolarization reserve (increased Ca²⁺/late Na⁺ currents and Na⁺/Ca²⁺-exchanger, reduced Na⁺/K⁺-pump) are highly vulnerable to drug-induced repolarization abnormalities, while those with reduced inward current density (fast/late Na⁺ and Ca²⁺ currents) exhibit high susceptibility to depolarization abnormalities. Repolarization abnormalities in silico predict clinical risk for all compounds with 89% accuracy. Drug-induced changes in biomarkers are in overall agreement across different assays: in silico AP duration changes reflect the ones observed in rabbit QT interval and hiPS-CMs Ca²⁺-transient, and simulated upstroke velocity captures variations in rabbit QRS complex. Our results demonstrate that human in silico drug trials constitute a powerful methodology for prediction of clinical pro-arrhythmic cardiotoxicity, ready for integration in the existing drug safety assessment pipelines.

Effect of Therapeutic and Supratherapeutic Doses of Vonoprazan on the QT/QTc Interval in a Phase I Randomized Study in Healthy Subjects

This phase I, randomized, 4-period, 4-sequence, double-blind, active- and placebo-controlled, crossover study assessed the effects of vonoprazan on the QT/QTc interval in healthy subjects. Subjects received single oral doses of vonoprazan 40 mg, vonoprazan 120 mg, moxifloxacin 400 mg (positive control/open label), and placebo. The primary end point was time-matched, placebo-corrected, baseline-adjusted mean Fridericia-corrected QT interval (ddQTcF). Of 64 subjects (mean age, 37.8 years; 50% male), 63 received all four regimens. One subject discontinued due to nondrug-related adverse event of tonsillitis. Assay sensitivity was established; lower bound of the one-sided 95% confidence interval (CI) for ddQTcF was >5 ms between 1.5 and 12 h following moxifloxacin administration. For both doses of vonoprazan, the one-sided upper 95% CI ddQTcF did not exceed 10 ms. There was no correlation between plasma vonoprazan concentrations and increases in ddQTcF. Vonoprazan was well tolerated. No severe adverse events/deaths were reported. (European Clinical Trials Database Registry: 2011-004003-20.).

Telavancin: a novel semisynthetic lipoglycopeptide agent to counter the challenge of resistant Gram-positive pathogens

Telavancin (TD-6424), a semisynthetic lipoglycopeptide vancomycin-derivative, is a novel antimicrobial agent developed by Theravance for overcoming resistant Gram-positive bacterial infections, specifically methicillin-resistant Staphylococcus aureus (MRSA). The US Food and Drug Administration (USFDA) had approved telavancin in 2009 for the treatment of complicated skin and skin structure infections (cSSSIs) caused by Gram-positive bacteria, including MRSA (S. aureus, Streptococcus agalactiae, Streptococcus pyogenes, Streptococcus anginosus group, or Enterococcus faecalis). Telavancin has two proposed mechanisms of action. In vitro, telavancin has a rapid, concentration-dependent bactericidal effect, due to disruption of cell membrane integrity. Telavancin has demonstrable in vitro activity against aerobic and anaerobic Gram-positive bacteria. Telavancin and vancomycin have similar spectra of activity. Gram-negative bacteria are usually non-susceptible to telavancin. Telavancin has been successfully tested in various animal models of bacteremia, endocarditis, meningitis, and pneumonia. Phase II Telavancin versus Standard Therapy for Treatment of Complicated Skin and Soft-Tissue Infections due to Gram-Positive Bacteria (FAST 1 and FAST 2) and phase III [Assessment of Telavancin in Complicated Skin and Skin Structure Infections 1 (ATLAS 1 and ATLAS 2)] clinical trials have been conducted for evaluating telavancin's efficacy and safety in cSSSIs. Phase III clinical trials have been carried out for evaluating telavancin's safety and efficacy in nosocomial pneumonia [Assessment of Telavancin for Treatment of Hospital acquired Pneumonia 1 and 2 (ATTAIN 1 and ATTAIN 2)]. A phase II randomized, double-blind, clinical trial has been carried out for evaluating telavancin's safety and efficacy in uncomplicated S. aureus bacteremia [Telavancin for Treatment of Uncomplicated S. aureus Bacteremia (ASSURE)]. Pacemaker lead-related infective endocarditis due to a vancomycin intermediate S. aureus (VISA) strain (non-daptomycin susceptible) was successfully treated with parenteral telavancin for 8 weeks. Telavancin extensively binds to serum albumin (~93%) and has a relatively small volume of distribution. Telavancin is not biotransformed by any cytochrome P450 microsomal enzymes and excreted mainly in the urine. Though well-tolerated, worrisome adverse effects, including renal dysfunction and QTc prolongation are of potential concern. Given its extensive binding to plasma proteins, long half-life, and a long post-antibiotic effect, it represents a promising addition to the therapeutic armamentarium in combating infections caused by resistant Gram-positive pathogens, namely, MRSA.

No Apparent Cardiac Conduction Effects of Acute Treatment with Risperidone in Children with Autism Spectrum Disorder

OBJECTIVES

Risperidone is approved for the treatment of serious behavioral problems in children with autism spectrum disorder (ASD). This study examined the effects of risperidone on cardiac conduction in children with ASD.

METHODS

Data were collected from an 8-week, five-site trial conducted by the Research Units on Pediatric Psychopharmacology Autism Network. Children (age 5-17 years) were randomly assigned to risperidone (n = 49) or placebo (n = 52) under double-blind conditions. Risperidone was superior to placebo in reducing serious behavioral problems. A standard 12-lead, electrocardiogram (ECG) was obtained in most subjects at screening and week 8. A pediatric electrophysiologist blind to treatment assignment reviewed all available ECGs for readability, abnormalities, and cardiac conduction parameters, including QTc. The electrophysiologist measurements were compared to machine readings. A second blinded electrophysiologist examined all available ECGs for abnormalities and a 20% random sample for QTc.

RESULTS

Of the 101 randomized subjects in the trial, complete pretreatment and week 8 data were available on 65 subjects (placebo n = 30; risperidone n = 35). The electrophysiologist did not identify any cardiac conduction adverse effects of risperidone and there was no difference in mean change on the QTc compared to placebo. The Bland-Altman plot showed a systematic bias in QTc measurements by the electrophysiologist and machine. Machine readings produced higher values than the electrophysiologist for shorter QTc intervals and machine scoring was lower than electrophysiologist readings for longer QTc values (p = 0.001). Two electrophysiologists had overall percent agreements of 82.9% (95% CI: 76.3 to 89.6) on qualitative assessment and 88.6% (95% CI: 79.3 to 98.0) on QTc interval.

CONCLUSION

Using conventional doses during acute treatment in children with ASD and serious behavioral problems, there was no difference in the mean change in QTc between risperidone and placebo. Compared to the electrophysiologist, the machine readings may miss elevated QTc measurements.

Early drug development: assessment of proarrhythmic risk and cardiovascular safety

INTRODUCTION

hERG assays and thorough ECG trials have been mandated since 2005 to evaluate the QT interval and potential proarrhythmic risk of new chemical entities. The high cost of these studies and the shortcomings inherent in these binary and limited approaches to drug evaluation have prompted regulators to search for more cost effective and mechanistic paradigms to assess drug liability as exemplified by the CiPA initiative and the exposure response ICH E14(R3) guidance document. Areas covered: This review profiles the changing regulatory landscape as it pertains to early drug development and outlines the analyses that can be performed to characterize preclinical and early clinical cardiovascular risk. Expert commentary: It is further acknowledged that the narrow focus on the QT interval needs to be expanded to include a more comprehensive evaluation of cardiovascular risk since unanticipated off target effects have led to the withdrawal of multiple drugs after they had been approved and marketed.

hERG1 potassium channel in cancer cells: a tool to reprogram immortality

It has been well established that changes in ion fluxes across cellular membranes as a function of time is fundamental in maintaining cellular homeostasis of every living cell. Consequently, dysregulation of ion channels activity is a critical event in pathological conditions of several tissues, including cancer. Nevertheless, the role of ion channels in cancer biology is still not well understood and very little is known about the possible therapeutic opportunities offered by the use of the vast collection of drugs that target ion channels. In this review, we focus on the recent advances in understanding the role of the voltage-gated hERG1 potassium channel in cancer and on the effects of pharmacologic manipulation of the hERG1 in cancer cells aiming to provide insights into the biochemical signaling and cellular processes that are altered by using these drugs.

Comparison of the spatial QRS-T angle derived from digital ECGs recorded using conventional electrode placement with that derived from Mason-Likar electrode position

BACKGROUND

The spatial QRS-T angle is ideally derived from orthogonal leads. We compared the spatial QRS-T angle derived from orthogonal leads reconstructed from digital 12-lead ECGs and from digital Holter ECGs recorded with the Mason-Likar (M-L) electrode positions.

METHODS AND RESULTS

Orthogonal leads were constructed by the inverse Dower method and used to calculate spatial QRS-T angle by (1) a vector method and (2) a net amplitude method, in 100 volunteers. Spatial QRS-T angles from standard and M-L ECGs differed significantly (57°±18° vs 48°±20° respectively using net amplitude method and 53°±28° vs 48°±23° respectively by vector method; p<0.001). Difference in amplitudes in leads V4-V6 was also observed between Holter and standard ECGs, probably due to a difference in electrical potential at the central terminal.

CONCLUSION

Mean spatial QRS-T angles derived from standard and M-L lead systems differed by 5°-9°. Though statistically significant, these differences may not be clinically significant.

Specific prediction of clinical QT prolongation by kinetic image cytometry in human stem cell derived cardiomyocytes

INTRODUCTION

A priority in the development and approval of new drugs is assessment of cardiovascular risk. Current methodologies for screening compounds (e.g. HERG testing) for proarrhythmic risk lead to many false positive and false negative results, resulting in the attrition of potentially therapeutic compounds in early development, and the advancement of other candidates that cause adverse effects. With improvements in the technologies of high content imaging and human stem cell differentiation, it is now possible to directly screen compounds for arrhythmogenic tendencies in human stem cell derived cardiomyocytes (hSC-CMs).

METHODS

A training panel of 90 compounds consisting of roughly equal numbers of QT-prolonging and negative control (non-QT-prolonging) compounds, and a follow-up blinded study of 35 compounds including 16 from the 90 compound panel and 2 duplicates, were evaluated for prolongation of the calcium transient in hSC-CMs using kinetic image cytometry (KIC), a specialized form of high content analysis.

RESULTS

The KIC-hSC-CM assay identified training compounds that prolong the calcium transient with 98% specificity, 97% precision, 80% sensitivity, and 89% accuracy in predicting clinical QT prolongation by these compounds. The follow-up study of 35 blinded compounds confirmed the reproducibility and strong diagnostic accuracy of the assay.

DISCUSSION

The correlation of the KIC-hSC-CM results to clinical observations met or surpassed traditional preclinical assessment of cardiac risk utilizing animal models. Thus, the KIC-hSC-CM assay, which can be accomplished in high throughput and at relatively low cost, is an effective new model system for testing chemicals for cardiovascular risk.

Detecting moxifloxacin-induced QTc prolongation in thorough QT and early clinical phase studies using a highly automated ECG analysis approach

BACKGROUND AND PURPOSE

Exposure-response (ER) modelling (concentration-QTc analysis) is gaining as much acceptance as the traditional by-time analysis of the placebo-adjusted change from baseline in the QTc interval (ΔΔQTcF). It has been postulated that intensive ECG analysis and ER modelling during early-phase drug development could be a cost-effective approach of estimating QT liability of a new drug, in a small number of subjects.

EXPERIMENTAL APPROACH

We used a highly automated analysis of ECGs from 46 subjects from a crossover thorough QT/QTc study to detect ΔΔQTcF with moxifloxacin. Using these data, we also simulated (bootstrapped) 1000 datasets of a parallel study with eight subjects receiving moxifloxacin and eight others receiving placebo.

KEY RESULTS

The slope from the concentration-QTc analysis for moxifloxacin in 46 subjects was 4.12 ms of ΔΔQTcF per μg(-1) mL(-1) ; at mean Cmax of 2.95 μg·mL(-1) , estimated ΔΔQTcF was 13.4 ms (90% confidence interval 11.3, 15.4 ms). In the 1000 simulated datasets, in 996 datasets, ER modelling showed that the upper bound of the 90% confidence interval for ΔΔQTcF at geometric mean Cmax exceeded 10 ms. In 895 of these 996 datasets, the slope of the ER relationship was statistically significantly positive. Thus, with a small sample size (eight subjects on active drug and eight on placebo), moxifloxacin-induced QTc prolongation was demonstrated using ER analysis with statistical power of >80%.

CONCLUSIONS AND IMPLICATIONS

Our study adds to the growing body of data supporting intensive ECG collection and analysis in early-phase studies to estimate QT liability.

Model-based evaluation of drug-induced QTc prolongation for compounds in early development

AIMS

Significant differences between dogs and humans have been observed in the concentration-QTc effect relationship of compounds with known pro-arrhythmic properties. These findings suggest that interspecies differences must be considered when evaluating drug effects. The aim of this study was to evaluate the performance of a model-based approach to assess the risk of QTc prolongation for three investigational compounds (NCE01, NCE02 and NCE03).

METHODS

Pharmacokinetic and pharmacodynamic data from experiments in conscious dogs and healthy subjects were included in this analysis. Pharmacokinetic modelling and deconvolution methods were applied to derive drug concentrations at the time of each QT measurement. An integrated pharmacokinetic-pharmacodynamic (PKPD) model was then used to describe QT prolongation. A threshold of ≥10 ms was used to characterize the probability of QTc prolongation.

RESULTS

The PKPD relationships of all three compounds were successfully described in both species. A strong effect was observed after administration of NCE01 to dogs and humans, with a slope of 0.0061 and 0.0662 ms nm(-1), respectively, and maximal probability of QTc prolongation ≥10 ms at peak concentration. For NCE02 and NCE03, QTc-shortening and borderline QT effects were observed both in dogs and humans, as described by negative or very shallow slopes (NCE02, -0.00098 and -0.01 ms nm(-1); NCE03, 0.00064 and -0.0002 ms nm(-1)).

CONCLUSIONS

Whilst NEC01 shows clear pro-arrhythmic effects, the liability for QT/QTc prolongation for NCE02 and NCE03 can be deemed low at the expected therapeutic exposure. Moreover, our results show the advantages of an integrated PKPD approach as the basis for translating pro-arrhythmic effects from dogs to humans.

The role of concentration-effect relationships in the assessment of QTc interval prolongation

Population pharmacokinetic and pharmacokinetic-pharmacodynamic (PKPD) modelling has been widely used in clinical research. Yet, its application in the evaluation of cardiovascular safety remains limited, particularly in the evaluation of pro-arrhythmic effects. Here we discuss the advantages of disadvantages of population PKPD modelling and simulation, a paradigm built around the knowledge of the concentration-effect relationship as the basis for decision making in drug development and its utility as a guide to drug safety. A wide-ranging review of the literature was performed on the experimental protocols currently used to characterize the potential for QT interval prolongation, both pre-clinically and clinically. Focus was given to the role of modelling and simulation for design optimization and subsequent analysis and interpretation of the data, discriminating drug from system specific properties. Cardiovascular safety remains one of the major sources of attrition in drug development with stringent regulatory requirements. However, despite the myriad of tests, data are not integrated systematically to ensure accurate translation of the observed drug effects in clinically relevant conditions. The thorough QT study addresses a critical regulatory question but does not necessarily reflect knowledge of the underlying pharmacology and has limitations in its ability to address fundamental clinical questions. It is also prone to issues of multiplicity. Population approaches offer a paradigm for the evaluation of drug safety built around the knowledge of the concentration-effect relationship. It enables quantitative assessment of the probability of QTc interval prolongation in patients, providing better guidance to regulatory labelling and understanding of benefit/risk in specific populations.

Changes in QTc associated with a rapid bolus dose of dexmedetomidine in patients receiving TIVA: a retrospective study

BACKGROUND

Clinical indications for the perioperative use of dexmedetomidine in pediatric anesthesia are accumulating. However, in 2013, dexmedetomidine was added to the list of medications with possible risk of prolonging the QT interval and/or inducing Torsades de Pointes. Unfortunately, current evidence for dexmedetomidine-induced QT prolongation is sparse and somewhat contradictory.

OBJECTIVE

The purpose of this study was to evaluate temporal changes in corrected QT interval (QTc) after a rapid bolus administration of dexmedetomidine under total intravenous anesthesia (TIVA) with a standardized propofol and remifentanil administration.

METHODS

Electrocardiography (ECG) and corresponding trend data were extracted from automated electronic data capture of physiological monitoring. Ten-second epochs of ECG data were extracted in 1-min intervals for 12 min, starting 1 min before dexmedetomidine bolus administration, and ending 10 min after. QT intervals were extracted using an automated routine in MATLAB, and corrected for heart rate (HR) using Bazett's (QTcB) and Fridericia's formulas (QTcF). QTcB and QTcF were compared using Wilcoxon signed-rank test between baseline measurements and the subsequent four interval values.

RESULTS

Data from 21 subjects (17 male) with median (range) age 7.1 (5.4-9.5) yr, weight 23.6 (16.2-36.7) kg, and height 121 (103-140) cm were analyzed. Bolus administration of dexmedetomidine reduced HR in all subjects (median 22%), and caused transient reduction of QT interval, with its peak at 1-min postbolus administration: QTcB (median reduction 30.7 ms, P < 0.001) or QTcF (median reduction 15.4 ms, P = 0.001); QT shortening became statistically insignificant 4 min following dexmedetomidine bolus administration for QTcB and 2 min for QTcF.

CONCLUSION

In this study, a rapid bolus of dexmedetomidine transiently shortened corrected QT intervals. However, these effects are confounded by dexmedetomidine-induced bradycardia. These findings should be confirmed in pediatric studies without concomitant TIVA administration and with optimized correction of baseline HR.

Digital Photoplethysmography for Assessment of Arterial Stiffness: Repeatability and Comparison with Applanation Tonometry

Introduction

Arterial stiffness is an independent risk factor for cardiovascular morbidity and can be assessed by applanation tonometry by measuring pulse wave velocity (PWV) and augmentation index (AIX) by pressure pulse wave analysis (PWA). As an inexpensive and operator independent alternative, photoelectric plethysmography (PPG) has been introduced with analysis of the digital volume pulse wave (DPA) and its second derivatives of wave reflections.

Objective

The objective was to investigate the repeatability of arterial stiffness parameters measured by digital pulse wave analysis (DPA) and the associations to applanation tonometry parameters.

Methods and Results

112 pregnant and non-pregnant individuals of different ages and genders were examined with SphygmoCor arterial wall tonometry and Meridian DPA finger photoplethysmography. Coefficients of repeatability, Bland-Altman plots, intraclass correlation coefficients and correlations to heart rate (HR) and body height were calculated for DPA variables, and the DPA variables were compared to tonometry variables left ventricular ejection time (LVET), PWV and AIX. No DPA variable showed any systematic measurement error or excellent repeatability, but dicrotic index (DI), dicrotic dilatation index (DDI), cardiac ejection elasticity index (EEI), aging index (AI) and second derivatives of the crude pulse wave curve, b/a and e/a, showed good repeatability. Overall, the correlations to AIX were better than to PWV, with correlations coefficients >0.70 for EEI, AI and b/a. Considering the level of repeatability and the correlations to tonometry, the overall best DPA parameters were EEI, AI and b/a. The two pansystolic time parameters, ejection time compensated (ETc) by DPA and LVET by tonometry, showed a significant but weak correlation.

Conclusion

For estimation of the LV function, ETc, EEI and b/a are suitable, for large artery stiffness EEI, and for small arteries DI and DDI. The only global parameter, AI, showed a high repeatability and the overall best correlations with AIX and PWV.

Considerations for assessing the potential effects of antidiabetes drugs on cardiac ventricular repolarization: A report from the Cardiac Safety Research Consortium

Thorough QT studies conducted according to the International Council on Harmonisation E14 guideline are required for new nonantiarrhythmic drugs to assess the potential to prolong ventricular repolarization. Special considerations may be needed for conducting such studies with antidiabetes drugs as changes in blood glucose and other physiologic parameters affected by antidiabetes drugs may prolong the QT interval and thus confound QT/corrected QT assessments. This review discusses potential mechanisms for QT/corrected QT interval prolongation with antidiabetes drugs and offers practical considerations for assessing antidiabetes drugs in thorough QT studies. This article represents collaborative discussions among key stakeholders from academia, industry, and regulatory agencies participating in the Cardiac Safety Research Consortium. It does not represent regulatory policy.

Antibody-drug conjugates for cancer therapy: The technological and regulatory challenges of developing drug-biologic hybrids

Antibody-drug conjugates (ADCs) are a new class of therapeutic agents that combine the targeting ability of monoclonal antibodies (mAbs) with small molecule drugs. The combination of a mAb targeting a cancer-specific antigen with a cytotoxin has tremendous promise as a new type of targeted cancer therapy. Two ADCs have been approved and many more are in clinical development, suggesting that this new class of drugs is coming to the forefront. Because of their unique nature as biologic-small drug hybrids, ADCs are challenging to develop, from both the scientific and regulatory perspectives. This review discusses both these aspects in current practice, and surveys the current state of the art of ADC drug development.

A thorough QT study to assess the effects of tbo-filgrastim on cardiac repolarization in healthy subjects

Tbo-filgrastim is a recombinant human granulocyte colony-stimulating factor approved by the US Food and Drug Administration to reduce the duration of severe neutropenia in patients with nonmyeloid malignancies receiving myelosuppressive anticancer drugs associated with a clinically significant incidence of febrile neutropenia. We assessed the effect of tbo-filgrastim on cardiac conduction and repolarization in healthy subjects. A three-arm, parallel-group, active- and placebo-controlled, double-blind study randomized healthy adults to a single 5 μg/kg intravenous tbo-filgrastim infusion, a single intravenous placebo infusion, or a single 400 mg moxifloxacin oral dose. The primary end point was placebo-corrected time-matched change from baseline in QT interval corrected using a QT individual correction (QTcI) method. Secondary end points included heart rate, PR interval, QRS duration, change in electrocardiogram patterns, correlation between QTcI change from baseline (milliseconds) and tbo-filgrastim serum concentrations, and safety variables. A total of 145 subjects were enrolled (50 tbo-filgrastim, 50 placebo, 45 moxifloxacin). Peak placebo-corrected change from baseline for QTcI with tbo-filgrastim was 3.5 milliseconds, with a two-sided 95% upper confidence interval of 7.2 milliseconds, demonstrating no signal for any tbo-filgrastim effect on QTc. Concentration-effect modeling showed no evidence of an effect of tbo-filgrastim on cardiac repolarization. Tbo-filgrastim produced no clinically significant changes in other electrocardiogram parameters. Tbo-filgrastim was well tolerated.

Evaluation of opicapone on cardiac repolarization in a thorough QT/QTc study

Opicapone, a novel third-generation catechol-O-methyltransferase inhibitor for use as adjunctive therapy in levodopa-treated Parkinson's disease patients, was investigated on cardiac repolarization in healthy adult volunteers. This was a single-center, randomized, double-blind, placebo-controlled, open-label active-controlled, 4-period crossover study conducted in 64 subjects. In each period, subjects received a single oral dose of 50 mg opicapone, 800 mg opicapone, placebo, or 400 mg moxifloxacin and 24-hour 12-lead Holter monitoring was performed on day -1 (baseline) and after each single dose. After a single oral administrations of 50 and 800 mg opicapone, opicapone was the major entity in the circulation, with a median tmax of 1.5-2.0 hours. Opicapone was rapidly eliminated, with an elimination half-life of 1-2 hours. There was no clinically relevant effect of 50 and 800 mg opicapone versus placebo on cardiac depolarization or repolarization. All upper bounds of the 1-sided 95% confidence interval (CI) were below 10 milliseconds, confirming that opicapone has no QT-prolonging effect. Moxifloxacin caused an increase in the QTcI, with a lower bound of the 2-sided 95% CI always higher than 5 milliseconds, around the tmax of peak concentration, demonstrating assay sensitivity. In conclusion, administration of opicapone at therapeutic (50 mg) and supratherapeutic (800 mg) doses did not induce a clinically significant prolongation of the QTc interval.

Thorough QT study of the effect of oral moxifloxacin on QTc interval in the fed and fasted state in healthy Japanese and Caucasian subjects

AIMS

The aims of this study were three-fold and were to (i) investigate the effect of food (fasted and fed state) on the degree of QT prolongation caused by moxifloxacin under the rigorous conditions of a TQT study, (ii) differentiate the effects on QTc that arise from changes in PK from those arising as a result of electrophysiological changes attributable to raised levels of C-peptide [11] offsetting in part the IKr blocking properties of moxifloxacin and (iii) characterize the QTc F profile of oral moxifloxacin (400 mg) in healthy Japanese volunteers compared with Caucasian subjects.

METHODS

The study population consisted of 32 healthy non-smoking, Caucasian (n = 13) and Japanese (n = 19), male and female subjects, aged between 20-45 years with a body mass index of between 18 to 25 kg m(-2). Female volunteers were required to use an effective contraceptive method or be abstinent. Subjects with ECGs which were deemed unsuitable for evaluation in a TQT study were excluded. ECGs were recorded in triplicate with subsequent blinded manual adjudication of the automated interval measurements. Electrocardiograms in the placebo arm were recorded twice in fasted and fed condition.

RESULTS

The results demonstrated a substantial change in the typical moxifloxacin effect on the ECG. The effect on ΔΔQTc in the fed state led to a significant delay and a modest reduction compared with the fasted state correcting both conditions with the corresponding placebo data. The largest QTc F change from baseline in the fed state was observed at 4 h with a peak value of 11.6 ms (two-sided 90% CI 9.1, 14.1). In comparison, the largest QTc F change observed in the fasted state was 14.4 ms (90% CI 11.9, 16.8) and occurred at 2.5 h post-dose. The PK of moxifloxacin were altered by food and this change was consistent with the observed QTc F change. In the fed state plasma concentrations of moxifloxacin were considerably and consistently lower in comparison with the fasted state, and this applied to both ethnicities. The concentration-effect analysis revealed that there was no change in slope and confirmed that the difference in this analysis was caused by a change in the PK profile of moxifloxacin. Comparisons of the moxifloxacin effect in the fed state compared with fasted placebo also revealed a pharmacodynamic effect whereby a meal appears to antagonize the effects of moxifloxacin on the lengths of the QTc interval.

CONCLUSIONS

Our findings demonstrate that the food effect by itself leads to a shortening of the QTc interval offsetting in part the effects of a 400 mg single dose of oral moxifloxacin. The typical moxifloxacin PK profile is also altered by food prior to dosing reducing the Cmax and delays the peak effects on QTc up to several hours thereby reducing the overall magnitude of the effect and delaying the peak QTc prolongation. The contribution of the two effects was clearly discernible. Given that moxifloxacin is sometimes given with food in TQT studies, consideration should be given to adequate baseline corrections and appropriate sampling time points. In this study the PK-PD relationship was similar for Japanese and Caucasian subjects in the fed and fasted conditions, thereby providing further evidence that the sensitivity to the QTc prolonging effects of fluoroquinolones was likely to be independent of ethnicity. The small differences observed between the two subpopulations were not statistically significant. However, future studies should give consideration to formal ethnic comparisons as a secondary outcome parameter as very little is known about the relationship between ethnicity and drug effects on cardiac repolarization.

Novel tetrahydropyran-based bacterial topoisomerase inhibitors with potent anti-gram positive activity and improved safety profile

Novel antibacterial drugs that are effective against infections caused by multidrug resistant pathogens are urgently needed. In a previous report, we have shown that tetrahydropyran-based inhibitors of bacterial type II topoisomerases (DNA gyrase and topoisomerase IV) display potent antibacterial activity and exhibit no target-mediated cross-resistance with fluoroquinolones. During the course of our optimization program, lead compound 5 was deprioritized due to adverse findings in cardiovascular safety studies. In the effort of mitigating these findings and optimizing further the pharmacological profile of this class of compounds, we have identified a subseries of tetrahydropyran-based molecules that are potent DNA gyrase and topoisomerase IV inhibitors and display excellent antibacterial activity against Gram positive pathogens, including clinically relevant resistant isolates. One representative of this class, compound 32d, elicited only weak inhibition of hERG K(+) channels and hNaV1.5 Na(+) channels, and no effects were observed on cardiovascular parameters in anesthetized guinea pigs. In vivo efficacy in animal infection models has been demonstrated against Staphylococcus aureus and Streptococcus pneumoniae strains.

A repeat-dose thorough QT study of inhaled fluticasone furoate/vilanterol combination in healthy subjects

AIMS

This study was designed as a thorough QT (TQT) study to evaluate the effects of fluticasone furoate (FF)/vilanterol (VI) in healthy subjects. Supportive data from a TQT study conducted with FF are also presented.

METHODS

This was a randomized, placebo- and positive-controlled, double-dummy, double-blind, four-way crossover study, in which healthy subjects (n = 85) were randomized to 7 days of once-daily treatment of FF/VI (200/25 or 800/100 μg) or placebo or single-dose oral moxifloxacin (single-blind, 400 mg). In the supportive TQT study, subjects (n = 40) were randomized to single-dose inhaled FF (4000 μg), oral moxifloxacin (400 mg) or placebo.

RESULTS

There was a lack of effect of FF/VI (200/25 μg) on QTcF (Fridericia's correction); all time-matched mean differences from baseline relative to placebo (0-24 h) were <5 ms, with upper 90% confidence intervals (CI) of <10 ms. At 800/100 μg, FF/VI had no significant clinical effect on QTcF except at 30 min postdose when the 90% CI was >10 ms [mean (90% CI), 9.6 ms (7.2, 12.0)]. No effect on QTci (individually corrected) was observed at either strength of FF/VI, with mean time-matched treatment differences <5 ms at all time points [upper 90% CIs <10 ms (0-24 h)]. Assay sensitivity was confirmed; moxifloxacin prolonged QTcF and QTci, with time-matched mean differences from baseline relative to placebo of >10 ms (1-8 h postdose).

CONCLUSIONS

Repeat once-daily dosing of FF/VI (200/25 μg), which is the highest therapeutic strength used in phase III studies, is not associated with QTc prolongation in healthy subjects. Supratherapeutic strength FF/VI (800/100 μg) demonstrated a small transient effect on QTcF but not on QTci.