Self-administered intranasal etripamil using a symptom-prompted, repeat-dose regimen for atrioventricular-nodal-dependent supraventricular tachycardia (RAPID): a multicentre, randomised trial.

BACKGROUND: Etripamil is a fast-acting, intranasally administered calcium-channel blocker in development for on-demand therapy outside a health-care setting for paroxysmal supraventricular tachycardia. We aimed to evaluate the efficacy and safety of etripamil 70 mg nasal spray using a symptom-prompted, repeat-dose regimen for acute conversion of atrioventricular-nodal-dependent paroxysmal supraventricular tachycardia to sinus rhythm within 30 min. METHODS: RAPID was a multicentre, randomised, placebo-controlled, event-driven trial, conducted at 160 sites in North America and Europe as part 2 of the NODE-301 study. Eligible patients were aged at least 18 years and had a history of paroxysmal supraventricular tachycardia with sustained, symptomatic episodes (≥20 min) as documented by electrocardiogram. Patients were administered two test doses of intranasal etripamil (each 70 mg, 10 min apart) during sinus rhythm; those who tolerated the test doses were randomly assigned (1:1) using an interactive response technology system to receive either etripamil or placebo. Prompted by symptoms of paroxysmal supraventricular tachycardia, patients self-administered a first dose of intranasal 70 mg etripamil or placebo and, if symptoms persisted beyond 10 min, a repeat dose. Continuously recorded electrocardiographic data were adjudicated, by individuals masked to patient assignment, for the primary endpoint of time to conversion of paroxysmal supraventricular tachycardia to sinus rhythm for at least 30 s within 30 min after the first dose, which was measured in all patients who administered blinded study drug for a confirmed atrioventricular-nodal-dependent event. Safety outcomes were assessed in all patients who self-administered blinded study drug for an episode of perceived paroxysmal supraventricular tachycardia. This trial is registered at ClinicalTrials.gov, NCT03464019, and is complete. FINDINGS: Between Oct 13, 2020, and July 20, 2022, among 692 patients randomly assigned, 184 (99 from the etripamil group and 85 from the placebo group) self-administered study drug for atrioventricular-nodal-dependent paroxysmal supraventricular tachycardia, with diagnosis and timing confirmed. Kaplan-Meier estimates of conversion rates by 30 min were 64% (63/99) with etripamil and 31% (26/85) with placebo (hazard ratio 2·62; 95% CI 1·66-4·15; p<0·0001). Median time to conversion was 17·2 min (95% CI 13·4-26·5) with the etripamil regimen versus 53·5 min (38·7-87·3) with placebo. Prespecified sensitivity analyses of the primary assessment were conducted to test robustness, yielding supporting results. Treatment-emergent adverse events occurred in 68 (50%) of 99 patients treated with etripamil and 12 (11%) of 85 patients in the placebo group, most of which were located at the administration site and were mild or moderate, and all of which were transient and resolved without intervention. Adverse events occurring in at least 5% of patients treated with etripamil were nasal discomfort (23%), nasal congestion (13%), and rhinorrhea (9%). No serious etripamil-related adverse events or deaths were reported. INTERPRETATION: Using a symptom-prompted, self-administered, initial and optional-repeat-dosing regimen, intranasal etripamil was well tolerated, safe, and superior to placebo for the rapid conversion of atrioventricular-nodal-dependent paroxysmal supraventricular tachycardia to sinus rhythm. This approach could empower patients to treat paroxysmal supraventricular tachycardia themselves outside of a health-care setting, and has the potential to reduce the need for additional medical interventions, such as intravenous medications given in an acute-care setting. FUNDING: Milestone Pharmaceuticals.

Gene- and variant-specific efficacy of serum/glucocorticoid-regulated kinase 1 inhibition in long QT syndrome types 1 and 2.

AIMS: Current long QT syndrome (LQTS) therapy, largely based on beta-blockade, does not prevent arrhythmias in all patients; therefore, novel therapies are warranted. Pharmacological inhibition of the serum/glucocorticoid-regulated kinase 1 (SGK1-Inh) has been shown to shorten action potential duration (APD) in LQTS type 3. We aimed to investigate whether SGK1-Inh could similarly shorten APD in LQTS types 1 and 2. METHODS AND RESULTS: Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and hiPSC-cardiac cell sheets (CCS) were obtained from LQT1 and LQT2 patients; CMs were isolated from transgenic LQT1, LQT2, and wild-type (WT) rabbits. Serum/glucocorticoid-regulated kinase 1 inhibition effects (300 nM-10 µM) on field potential durations (FPD) were investigated in hiPSC-CMs with multielectrode arrays; optical mapping was performed in LQT2 CCS. Whole-cell and perforated patch clamp recordings were performed in isolated LQT1, LQT2, and WT rabbit CMs to investigate SGK1-Inh (3 µM) effects on APD. In all LQT2 models across different species (hiPSC-CMs, hiPSC-CCS, and rabbit CMs) and independent of the disease-causing variant (KCNH2-p.A561V/p.A614V/p.G628S/IVS9-28A/G), SGK1-Inh dose-dependently shortened FPD/APD at 0.3-10 µM (by 20-32%/25-30%/44-45%). Importantly, in LQT2 rabbit CMs, 3 µM SGK1-Inh normalized APD to its WT value. A significant FPD shortening was observed in KCNQ1-p.R594Q hiPSC-CMs at 1/3/10 µM (by 19/26/35%) and in KCNQ1-p.A341V hiPSC-CMs at 10 µM (by 29%). No SGK1-Inh-induced FPD/APD shortening effect was observed in LQT1 KCNQ1-p.A341V hiPSC-CMs or KCNQ1-p.Y315S rabbit CMs at 0.3-3 µM. CONCLUSION: A robust SGK1-Inh-induced APD shortening was observed across different LQT2 models, species, and genetic variants but less consistently in LQT1 models. This suggests a genotype- and variant-specific beneficial effect of this novel therapeutic approach in LQTS.

Rationale for and design of a multicenter, placebo-controlled, phase 3 study to assess efficacy and safety of intranasal etripamil for the conversion of paroxysmal supraventricular tachycardia.

Presently, acute pharmacological termination of paroxysmal supraventricular tachycardia (PSVT) unresponsive to patient-initiated vagal maneuvers requires in-hospital intervention. Etripamil, a fast-acting, nondihydropyridine, L-type calcium channel blocker, is formulated as an intranasal spray to rapidly terminate atrioventricular (AV) nodal-dependent PSVT in a medically unsupervised setting. The NODE-301 study did not meet its prespecified primary end point of PSVT conversion over 5 hours following a single dose of etripamil 70 mg. However, analysis at earlier time points demonstrated etripamil treatment effect during the first 30 minutes, consistent with its expected rapid onset and short duration of action. This led to the design of the RAPID study, which includes a new dosing regimen (up to 2 etripamil 70 mg doses separated by 10 minutes) to increase the exposure and pharmacodynamic effect of etripamil. The primary objective of RAPID (NCT03464019) is to determine if etripamil self-administered by patients is superior to placebo in terminating PSVT in an at-home setting. The secondary objective is to evaluate the safety of etripamil when self-administered by patients without medical supervision. Additional efficacy end points include the proportion of patients requiring additional medical intervention in an emergency department to terminate PSVT and patient-reported outcomes. After successfully completing a test dose to assess the safety of 2 70 mg doses of etripamil during sinus rhythm, approximately 500 patients will be randomized 1:1 to etripamil or placebo to accrue 180 positively adjudicated AV nodal-dependent PSVT events for treatment with the study drug. Etripamil may offer a new alternative to the current in-hospital treatment modality, providing for safe and effective at-home termination of PSVT.

Is there a role for pharmacokinetic/pharmacodynamic-guided dosing for novel oral anticoagulants?

The novel direct oral anticoagulants (NOACs) represent a major advance in oral anticoagulant therapy and are replacing vitamin K antagonists as the preferred options for many indications. Given in fixed doses without routine laboratory monitoring, they have been shown to be at least as effective in reducing thromboembolic stroke as dose-adjusted warfarin in phase 3 randomized trials and less likely to cause hemorrhagic stroke. Pharmacokinetic and/or pharmacodynamic subanalyses of the major NOAC trials in patients with atrial fibrillation have established relationships between clinical characteristics, and drug levels and/or pharmacodynamic responses with both efficacy and safety. Based on these analyses, pharmaceutical manufacturers and regulatory authorities have provided contraindications and dosing recommendations based on clinical characteristics that are associated with drug levels and/or pharmacodynamic responses, stroke reduction, and bleeding risk to optimize the risk-benefit profile of the NOACs in the real world. The current fixed-dosing strategy of NOACs has triggered discussions about the potential value of laboratory monitoring and dose adjustment in customizing drug exposure to further improve the safety and efficacy of the NOACs in patients with atrial fibrillation. As there is neither high-quality evidence nor consensus about the potential role of laboratory monitoring and dose adjustment for the NOACs, a Cardiac Research Safety Consortium "Think Tank" meeting was held at the American College of Cardiology Heart House in December 2015 to discussions these issues. This manuscript reports on the deliberations and the conclusions reached at that meeting.

Solithromycin, a novel macrolide, does not prolong cardiac repolarization: a randomized, three-way crossover study in healthy subjects.

BACKGROUND: Macrolide antibiotics may cause QT prolongation. OBJECTIVES: To study the QT effect of a novel macrolide, solithromycin. METHODS: This was a thorough QT study with a three-way crossover design performed in healthy male and female subjects to evaluate the ECG effects of a novel macrolide, solithromycin. Forty-eight subjects were randomized to receive 800 mg of intravenous (iv) solithromycin, 400 mg of oral moxifloxacin and placebo in three separate treatment periods. Continuous 12 lead ECGs were recorded at a pre-dose baseline and serially after drug administration for 24 h. RESULTS: After the 40 min infusion of 800 mg of solithromycin, the geometric mean solithromycin peak plasma concentration (Cmax) reached 5.9 (SD: 1.30) µg/mL. Solithromycin infusion caused a heart rate increase with a peak effect of 15 bpm immediately after the end of the infusion. The change-from-baseline QTcF (ΔQTcF) was similar after dosing with solithromycin and placebo and the resulting placebo-corrected ΔQTcF (ΔΔQTcF) for solithromycin was therefore small at all timepoints with a peak effect at 4 h of only 2.8 ms (upper bound of the 90% CI: 4.9 ms). Using a linear exposure-response model, a statistically significant, slightly negative slope of -0.86 ms per ng/mL (90% CI: -1.19 to -0.53; P = 0.0001) was observed with solithromycin. The study's ability to detect small QT changes was confirmed by the moxifloxacin response. Solithromycin did not have a clinically meaningful effect on the PR or QRS interval. CONCLUSIONS: The study demonstrated that solithromycin, unlike other macrolide antibiotics, does not cause QT prolongation.

Finding the rhythm of sudden cardiac death: new opportunities using induced pluripotent stem cell-derived cardiomyocytes.

Sudden cardiac death is a common cause of death in patients with structural heart disease, genetic mutations, or acquired disorders affecting cardiac ion channels. A wide range of platforms exist to model and study disorders associated with sudden cardiac death. Human clinical studies are cumbersome and are thwarted by the extent of investigation that can be performed on human subjects. Animal models are limited by their degree of homology to human cardiac electrophysiology, including ion channel expression. Most commonly used cellular models are cellular transfection models, which are able to mimic the expression of a single-ion channel offering incomplete insight into changes of the action potential profile. Induced pluripotent stem cell-derived cardiomyocytes resemble, but are not identical, adult human cardiomyocytes and provide a new platform for studying arrhythmic disorders leading to sudden cardiac death. A variety of platforms exist to phenotype cellular models, including conventional and automated patch clamp, multielectrode array, and computational modeling. Induced pluripotent stem cell-derived cardiomyocytes have been used to study long QT syndrome, catecholaminergic polymorphic ventricular tachycardia, hypertrophic cardiomyopathy, and other hereditary cardiac disorders. Although induced pluripotent stem cell-derived cardiomyocytes are distinct from adult cardiomyocytes, they provide a robust platform to advance the science and clinical care of sudden cardiac death.

The Cardiac Safety Research Consortium enters its second decade: An invitation to participate.

The Cardiac Safety Research Consortium (CSRC), a transparent, public-private partnership established in 2005 as a Critical Path Program and formalized in 2006 under a Memorandum of Understanding between the United States Food and Drug Administration and Duke University, is entering its second decade. Our continuing goal is to advance paradigms for more efficient regulatory science related to the cardiovascular safety of new therapeutics, both in the United States and globally, particularly where such safety questions add burden to innovative research and development. Operationally, CSRC brings together a broad base of stakeholders from academia, industry, and government agencies in a collaborative forum focused on identifying barriers and then creating novel solutions through shared data, expertise, and collaborative research. This white paper provides a brief overview of the Consortium's activities in its first decade and a context for some of our current activities and future directions. The growth and success of the CSRC have been primarily driven by members' active participation and the development of goodwill and trust throughout our membership, which have facilitated novel collaborations across traditionally competitive or contentious stakeholder boundaries. The continued expansion of our base of participating academicians, industry experts, and regulators will define the Consortium's success in our second decade. It is our hope that sharing our endeavors to date will stimulate additional participation in the CSRC and also provide a model for other groups starting to develop similar collaborative forums.

Cardiovascular safety for once-weekly dulaglutide in type 2 diabetes: a pre-specified meta-analysis of prospectively adjudicated cardiovascular events.

BACKGROUND: Patients with type 2 diabetes (T2D) have a substantial increased risk for cardiovascular (CV) disease and associated mortality than those without diabetes. Dulaglutide is a once-weekly glucagon-like peptide-1 receptor agonist that is approved for treatment of T2D. METHODS: This meta-analysis evaluates the CV risk in patients with T2D treated with dulaglutide in 9 randomized safety and efficacy trials. Mean (median) treatment duration was 333 (358) days. Reported CV events were independently adjudicated by a treatment-blinded clinical endpoint committee. The primary measure was a 4-component major adverse CV event (4-component MACE) composite endpoint of death due to CV causes, nonfatal myocardial infarction (MI), nonfatal stroke, or hospitalization for unstable angina. Additional pre-specified endpoints included adjudicated coronary revascularizations, hospitalization for heart failure, and all-cause mortality. A Cox proportional hazards regression model (stratified by study) was used to estimate the hazard ratio (HR) and confidence interval (CI). Tests of treatment effects for the primary endpoint were conducted at a 2-sided alpha level of 0.0198 and a corresponding 98.02 % CI was calculated. Statistical heterogeneity between the strata (studies) was tested by including in the Cox model an interaction term between treatment and strata. RESULTS: The analysis included 6010 randomized patients [dulaglutide: 3885; comparator therapy (active or placebo): 2125]; cumulative exposure to dulaglutide or comparator therapy was 3941 and 2223 patient-years, respectively. The demographic and baseline CV disease characteristics were similar across groups. Twenty-six (0.67 %) patients in the dulaglutide group versus 25 (1.18 %) in the comparator group experienced a primary 4-component MACE (HR 0.57; adjusted 98.02 % CI 0.30, 1.10). Results for the 3-component MACE (composite endpoint of death due to CV causes, nonfatal MI or stroke), 6-component MACE (composite endpoint of death due to CV causes, nonfatal MI or stroke, hospitalization for unstable angina or heart failure, or coronary revascularizations) and all-cause mortality were consistent with the primary analysis (HR < 1.0 for all). CONCLUSIONS: These results suggest that dulaglutide does not increase the risk of major CV events in T2D patients. The ongoing CV outcomes study, Researching CV Events with a Weekly Incretin in Diabetes (REWIND), will further assess CV safety of dulaglutide.

Cardiovascular Safety Outcome Trials: A meeting report from the Cardiac Safety Research Consortium.

This White Paper provides a summary of presentations and discussions at a Cardiovascular Safety Outcome Trials Think Tank cosponsored by the Cardiac Safety Research Consortium, the US Food and Drug Administration, and the American College of Cardiology, held at American College of Cardiology's Heart House, Washington, DC, on February 19, 2014. Studies to assess cardiovascular (CV) risk of a new drug are sometimes requested by regulators to resolve ambiguous safety signals seen during its development or among other members of its class. Think Tank participants thought that important considerations in undertaking such studies were as follows: (1) plausibility-how likely it is that a possible signal indicating risk is real, based on strength of evidence, and/or whether a plausible mechanism of action for potential CV harm has been identified; (2) relevance-what relative and absolute CV risk would need to be excluded to determine that the drug had an acceptable benefit-to-risk balance for its use in the intended patient population; and (3) how plausibility and relevance influence the timing and approach to further safety assessment.

Centralized adjudication of cardiovascular end points in cardiovascular and noncardiovascular pharmacologic trials: a report from the Cardiac Safety Research Consortium.

This white paper provides a summary of presentations and discussions at a cardiovascular (CV) end point adjudication think tank cosponsored by the Cardiac Safety Research Committee and the US Food and Drug Administration (FDA) that was convened at the FDA's White Oak headquarters on November 6, 2013. Attention was focused on the lack of clarity concerning the need for end point adjudication in both CV and non-CV trials: there is currently an absence of widely accepted academic or industry standards and a definitive regulatory policy on how best to structure and use clinical end point committees (CECs). This meeting therefore provided a forum for leaders in the fields of CV clinical trials and CV safety to develop a foundation of initial best practice recommendations for use in future CEC charters. Attendees included representatives from pharmaceutical companies, regulatory agencies, end point adjudication specialist groups, clinical research organizations, and active, academically based adjudicators. The manuscript presents recommendations from the think tank regarding when CV end point adjudication should be considered in trials conducted by cardiologists and by noncardiologists as well as detailing key issues in the composition of a CEC and its charter. In addition, it presents several recommended best practices for the establishment and operation of CECs. The science underlying CV event adjudication is evolving, and suggestions for additional areas of research will be needed to continue to advance this science. This manuscript does not constitute regulatory guidance.

Novel oral anticoagulants and reversal agents: Considerations for clinical development.

This white paper provides a summary of presentations and discussions that were held at an Anticoagulant-Induced Bleeding and Reversal Agents Think Tank co-sponsored by the Cardiac Safety Research Consortium and the US Food and Drug Administration (FDA) at the FDA's White Oak Headquarters on April 22, 2014. Attention focused on a development pathway for reversal agents for the novel oral anticoagulants (NOACs). This is important because anticoagulation is still widely underused for stroke prevention in patients with atrial fibrillation. Undertreatment persists, although NOACs, in general, overcome some of the difficulties associated with anticoagulation provided by vitamin K antagonists. One reason for the lack of a wider uptake is the absence of NOAC reversal agents. As there are neither widely accepted academic and industry standards nor a definitive regulatory policy on the development of such reversal agents, this meeting provided a forum for leaders in the fields of cardiovascular clinical trials and cardiovascular safety to discuss the issues and develop recommendations. Attendees included representatives from pharmaceutical companies; regulatory agencies; end point adjudication specialist groups; contract research organizations; and active, academically based physicians. There was wide and solid consensus that NOACs overall offer improvements in convenience, efficacy, and safety compared with warfarin, even without reversal agents. Still, it was broadly accepted that it would be helpful to have reversal agents available for clinicians to use. Because it is not feasible to do definitive outcomes studies demonstrating a reversal agent's clinical benefits, it was felt that these agents could be approved for use in life-threatening bleeding situations if the molecules were well characterized preclinically, their pharmacodynamic and pharmacokinetic profiles were well understood, and showed no harmful adverse events in early human testing. There was also consensus that after such approval, efforts should be made to augment the available clinical information until such time as there is a body of evidence to demonstrate real-world clinical outcomes with the reversal agents. No recommendations were made for more generalized use of these agents in the setting of non-life-threatening situations. This article reflects the views of the authors and should not be construed to represent FDA's views or policies.

Rechanneling the cardiac proarrhythmia safety paradigm: a meeting report from the Cardiac Safety Research Consortium.

This white paper provides a summary of a scientific proposal presented at a Cardiac Safety Research Consortium/Health and Environmental Sciences Institute/Food and Drug Administration-sponsored Think Tank, held at Food and Drug Administration's White Oak facilities, Silver Spring, MD, on July 23, 2013, with the intention of moving toward consensus on defining a new paradigm in the field of cardiac safety in which proarrhythmic risk would be primarily assessed using nonclinical in vitro human models based on solid mechanistic considerations of torsades de pointes proarrhythmia. This new paradigm would shift the emphasis from the present approach that strongly relies on QTc prolongation (a surrogate marker of proarrhythmia) and could obviate the clinical Thorough QT study during later drug development. These discussions represent current thinking and suggestions for furthering our knowledge and understanding of the public health case for adopting a new, integrated nonclinical in vitro/in silico paradigm, the Comprehensive In Vitro Proarrhythmia Assay, for the assessment of a candidate drug's proarrhythmic liability, and for developing a public-private collaborative program to characterize the data content, quality, and approaches required to assess proarrhythmic risk in the absence of a Thorough QT study. This paper seeks to encourage multistakeholder input regarding this initiative and does not represent regulatory guidance.

The evaluation and management of drug effects on cardiac conduction (PR and QRS intervals) in clinical development.

Recent advances in electrocardiographic monitoring and waveform analysis have significantly improved the ability to detect drug-induced changes in cardiac repolarization manifested as changes in the QT/corrected QT interval. These advances have also improved the ability to detect drug-induced changes in cardiac conduction. This White Paper summarizes current opinion, reached by consensus among experts at the Cardiac Safety Research Consortium, on the assessment of electrocardiogram-based safety measurements of the PR and QRS intervals, representing atrioventricular and ventricular conduction, respectively, during drug development.

SGK1 inhibition attenuated the action potential duration in patient- and genotype-specific re-engineered heart cells with congenital long QT syndrome.

Background: Long QT syndrome (LQTS) stems from pathogenic variants in KCNQ1 (LQT1), KCNH2 (LQT2), or SCN5A (LQT3) and is characterized by action potential duration (APD) prolongation. Inhibition of serum and glucocorticoid regulated kinase-1 (SGK1) is proposed as a novel therapeutic for LQTS. Objective: The study sought to test the efficacy of novel, selective SGK1 inhibitors in induced pluripotent stem cell-derived cardiomyocyte (iPSC-CM) models of LQTS. Methods: The mexiletine (MEX)-sensitive SCN5A-P1332L iPSC-CMs were tested initially compared with a CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 SCN5A-P1332L variant-corrected isogenic control (IC). The SGK1-I1 therapeutic efficacy, compared with MEX, was tested for APD at 90% repolarization (APD90) shortening in SCN5A-P1332L, SCN5A-R1623Q, KCNH2-G604S, and KCNQ1-V254M iPSC-CMs using FluoVolt. Results: The APD90 was prolonged in SCN5A-P1332L iPSC-CMs compared with its IC (646 ± 7 ms vs 482 ± 23 ms; P < .0001). MEX shortened the APD90 to 560 ± 7 ms (52% attenuation, P < .0001). SGK1-I1 shortened the APD90 to 518 ± 5 ms (78% attenuation, P < .0001) but did not shorten the APD90 in the IC. SGK1-I1 shortened the APD90 of the SCN5A-R1623Q iPSC-CMs (753 ± 8 ms to 475 ± 19 ms compared with 558 ± 19 ms with MEX), the KCNH2-G604S iPSC-CMs (666 ± 10 ms to 574 ± 18 ms vs 538 ± 15 ms after MEX), and the KCNQ1-V254M iPSC-CMs (544 ± 10 ms to 475 ± 11ms; P = .0004). Conclusions: Therapeutically inhibiting SGK1 effectively shortens the APD in human iPSC-CM models of the 3 major LQTS genotypes. These preclinical data support development of SGK1 inhibitors as novel, first-in-class therapy for patients with congenital LQTS.

SGK1 inhibition attenuates the action potential duration in reengineered heart cell models of drug-induced QT prolongation.

BACKGROUND: Drug-induced QT prolongation (DI-QTP) is a clinical entity in which administration of a human ether-à-go-go-related gene/rapid delayed rectifier potassium current blocker such as dofetilide prolongs the cardiac action potential duration (APD) and the QT interval on the electrocardiogram. Inhibition of serum and glucocorticoid regulated kinase-1 (SGK1) reduces the APD at 90% repolarization (APD90) in induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) derived from patients with congenital long QT syndrome. OBJECTIVE: Here, we test the efficacy of 2 novel SGK1 inhibitors-SGK1-I1 and SGK1-I2-in iPSC-CM models of dofetilide-induced APD prolongation. METHODS: Normal iPSC-CMs were treated with dofetilide to produce a DI-QTP iPSC-CM model. SGK1-I1's and SGK1-I2's therapeutic efficacy for shortening the dofetilide-induced APD90 prolongation was compared to mexiletine. The APD90 values were recorded 4 hours after treatment using a voltage-sensing dye. RESULTS: The APD90 was prolonged in normal iPSC-CMs treated with dofetilide (673 ± 8 ms vs 436 ± 4 ms; P < .0001). While 10 mM mexiletine shortened the APD90 of dofetilide-treated iPSC-CMs from 673 ± 4 to 563 ± 8 ms (46% attenuation; P < .0001), 30 nM of SGK1-I1 shortened the APD90 from 673 ± 8 to 502 ± 7 ms (72% attenuation; P < .0001). Additionally, 300 nM SGK1-I2 shortened the APD90 of dofetilide-treated iPSC-CMs from 673 ± 8 to 460 ± 7 ms (90% attenuation; P < .0001). CONCLUSION: These novel SGK1-Is substantially attenuated the pathological APD prolongation in a human heart cell model of DI-QTP. These preclinical data support the development of this therapeutic strategy to counter and neutralize DI-QTP, thereby increasing the safety profile for patients receiving drugs with torsadogenic potential.

Cardiac imaging approaches to evaluate drug-induced myocardial dysfunction.

The ability to make informed benefit-risk assessments for potentially cardiotoxic new compounds is of considerable interest and importance at the public health, drug development, and individual patient levels. Cardiac imaging approaches in the evaluation of drug-induced myocardial dysfunction will likely play an increasing role. However, the optimal choice of myocardial imaging modality and the recommended frequency of monitoring are undefined. These decisions are complicated by the array of imaging techniques, which have varying sensitivities, specificities, availabilities, local expertise, safety, and costs, and by the variable time-course of tissue damage, functional myocardial depression, or recovery of function. This White Paper summarizes scientific discussions of members of the Cardiac Safety Research Consortium on the main factors to consider when selecting nonclinical and clinical cardiac function imaging techniques in drug development. We focus on 3 commonly used imaging modalities in the evaluation of cardiac function: echocardiography, magnetic resonance imaging, and radionuclide (nuclear) imaging and highlight areas for future research.

A Phase 1 Clinical Study Evaluating the Effects of Cenobamate on the QT Interval.

Cenobamate is an antiseizure medication for uncontrolled focal seizures. This thorough QT study assessed the effects of therapeutic and supratherapeutic cenobamate doses (maximum recommended dose, 400 mg/day) on correct QT interval (QTc) in healthy adults (N = 108) randomly assigned to 1 of 3 treatments: (A) cenobamate (days 1-63) up-titrated by 50-mg increments weekly to a 200 mg/day therapeutic dose (day 35) and then by 100 mg weekly to a 500 mg/day supratherapeutic dose (day 63), with placebo-moxifloxacin (days -1 and 64); (B) moxifloxacin 400 mg (day -1; positive control), placebo-cenobamate (days 1-63), and placebo-moxifloxacin (day 64); and (C) placebo-moxifloxacin (day -1), placebo-cenobamate (days 1-64), and moxifloxacin 400 mg (day 64). The primary end point was baseline-adjusted, placebo-corrected QTc (ΔΔQTcF; corrected for heart rate [HR] by Fridericia's method) with cenobamate 200 and 500 mg/day. Baseline electrocardiographic parameters were balanced across groups. Mean ΔΔQTcF was negative throughout for cenobamate doses (largest: day 35, -10.8 milliseconds; day 63, -18.4 milliseconds). Based on concentration-QTc analysis, ∆∆QTcF effect was predicted as -9.85 and -17.14 milliseconds at mean peak plasma levels of therapeutic (200 mg/day; 23.06 µg/mL) and supratherapeutic (500 mg/day; 63.96 µg/mL) doses. Cenobamate had no clinically relevant prolonging effect on electrocardiographic parameters (eg, PR, QRS); HR effects were similar to placebo. Cenobamate showed slight dose-related shortening of QTc, but to a degree not known to be clinically relevant (no reductions ≤340 milliseconds). Cenobamate had no clinically relevant effects on HR or electrocardiographic parameters and no QTc-prolonging effect at therapeutic/supratherapeutic doses. Cenobamate is contraindicated in patients with short-QT syndrome and caution should be used when coadministering with drugs that shorten QT interval.

First Randomized, Multicenter, Placebo-Controlled Study of Self-Administered Intranasal Etripamil for Acute Conversion of Spontaneous Paroxysmal Supraventricular Tachycardia (NODE-301).

BACKGROUND: Pharmacologic termination of paroxysmal supraventricular tachycardia (PSVT) often requires medically supervised intervention. Intranasal etripamil, is an investigational fast-acting, nondihydropyridine, L-type calcium channel blocker, designed for unsupervised self-administration to terminate atrioventricular nodal-dependent PSVT. Phase 2 results showed potential safety and efficacy of etripamil in 104 patients with PSVT. METHODS: NODE-301, a phase 3, multicenter, double-blind, placebo-controlled study evaluated the efficacy and safety of etripamil nasal spray administered, unsupervised in patients with symptomatic sustained PSVT. After a medically supervised etripamil test dose while in sinus rhythm, patients were randomized 2:1 to receive etripamil 70 mg or placebo. When PSVT symptoms developed, patients applied a cardiac monitor and attempted a vagal maneuver; if symptoms persisted, they self-administered blinded treatment. An independent Adjudication Committee reviewed continuous electrocardiogram recordings. The primary efficacy endpoint was termination of adjudicated PSVT within 5 hours after study drug administration. RESULTS: NODE-301 accrued 156 positively adjudicated PSVT events treated with etripamil (n=107) or placebo (n=49). The hazard ratio for the primary endpoint, time-to-conversion to sinus rhythm during the 5-hour observation period, was 1.086 (95% CI, 0.726-1.623; P=0.12). In predefined sensitivity analyses, etripamil effects (compared with placebo) occurred at 3, 5, 10, 20, and 30 minutes (P<0.05). For example, at 30 minutes, there was a 53.7% of SVT conversion in the treatment arm compared to 34.7% in the placebo arm (hazard ratio, 1.87 [95% CI, 1.09-3.22]; P=0.02). Etripamil was well tolerated; adverse events were mainly related to transient nasal discomfort and congestion (19.6% and 8.0%, respectively, of randomized treatment-emergent adverse events. CONCLUSIONS: Although the primary 5-hour efficacy endpoint was not met, analyses at earlier time points indicated an etripamil treatment effect in terminating PSVT. Etripamil self-administration during PSVT was safe and well tolerated. These results support continued clinical development of etripamil nasal spray for self-administration during PSVT in a medically unsupervised setting. REGISTRATION: URL: https://www. CLINICALTRIALS: gov; Unique identifier: NCT03464019.

Multicenter validation of the diagnostic accuracy of a blood-based gene expression test for assessing obstructive coronary artery disease in nondiabetic patients.

BACKGROUND: Diagnosing obstructive coronary artery disease (CAD) in at-risk patients can be challenging and typically requires both noninvasive imaging methods and coronary angiography, the gold standard. Previous studies have suggested that peripheral blood gene expression can indicate the presence of CAD. OBJECTIVE: To validate a previously developed 23-gene, expression-based classification test for diagnosis of obstructive CAD in nondiabetic patients. DESIGN: Multicenter prospective trial with blood samples obtained before coronary angiography. (ClinicalTrials.gov registration number: NCT00500617) SETTING: 39 centers in the United States. PATIENTS: An independent validation cohort of 526 nondiabetic patients with a clinical indication for coronary angiography. MEASUREMENTS: Receiver-operating characteristic (ROC) analysis of classifier score measured by real-time polymerase chain reaction, additivity to clinical factors, and reclassification of patient disease likelihood versus disease status defined by quantitative coronary angiography. Obstructive CAD was defined as 50% or greater stenosis in 1 or more major coronary arteries by quantitative coronary angiography. RESULTS: The area under the ROC curve (AUC) was 0.70 ± 0.02 (P < 0.001); the test added to clinical variables (Diamond-Forrester method) (AUC, 0.72 with the test vs. 0.66 without; P = 0.003) and added somewhat to an expanded clinical model (AUC, 0.745 with the test vs. 0.732 without; P = 0.089). The test improved net reclassification over both the Diamond-Forrester method and the expanded clinical model (P < 0.001). At a score threshold that corresponded to a 20% likelihood of obstructive CAD (14.75), the sensitivity and specificity were 85% and 43% (yielding a negative predictive value of 83% and a positive predictive value of 46%), with 33% of patient scores below this threshold. LIMITATION: Patients with chronic inflammatory disorders, elevated levels of leukocytes or cardiac protein markers, or diabetes were excluded. CONCLUSION: A noninvasive whole-blood test based on gene expression and demographic characteristics may be useful for assessing obstructive CAD in nondiabetic patients without known CAD. PRIMARY FUNDING SOURCE: CardioDx.

Why translation from basic discoveries to clinical applications is so difficult for atrial fibrillation and possible approaches to improving it.

Atrial fibrillation (AF) is the most common sustained clinical arrhythmia, with a lifetime incidence of up to 37%, and is a major contributor to population morbidity and mortality. Important components of AF management include control of cardiac rhythm, rate, and thromboembolic risk. In this narrative review article, we focus on rhythm-control therapy. The available therapies for cardiac rhythm control include antiarrhythmic drugs and catheter-based ablation procedures; both of these are presently neither optimally effective nor safe. In order to develop improved treatment options, it is necessary to use preclinical models, both to identify novel mechanism-based therapeutic targets and to test the effects of putative therapies before initiating clinical trials. Extensive research over the past 30 years has provided many insights into AF mechanisms that can be used to design new rhythm-maintenance approaches. However, it has proven very difficult to translate these mechanistic discoveries into clinically applicable safe and effective new therapies. The aim of this article is to explore the challenges that underlie this phenomenon. We begin by considering the basic problem of AF, including its clinical importance, the current therapeutic landscape, the drug development pipeline, and the notion of upstream therapy. We then discuss the currently available preclinical models of AF and their limitations, and move on to regulatory hurdles and considerations and then review industry concerns and strategies. Finally, we evaluate potential paths forward, attempting to derive insights from the developmental history of currently used approaches and suggesting possible paths for the future. While the introduction of successful conceptually innovative new treatments for AF control is proving extremely difficult, one significant breakthrough is likely to revolutionize both AF management and the therapeutic development landscape.