Drugs, QTc interval prolongation and final ICH E14 guideline : an important milestone with challenges ahead.

Regulatory concerns on the ability of an ever-increasing number of non-antiarrhythmic drugs to delay ventricular repolarisation, prolong the corrected QT (QTc) interval and induce potentially fatal ventricular tachyarrhythmias have culminated in the adoption of two, internationally harmonised, regulatory guidelines. On 12 May 2005, the International Conference on Harmonisation (ICH) reached an important milestone when it adopted the final texts for clinical (ICH topic E14) and non-clinical (ICH topic S7B) strategies by which drugs should be investigated for their potential to induce these effects during their development.ICH E14 provides recommendations to sponsors concerning the design, conduct, analysis and interpretation of clinical studies to assess the potential of a drug to delay cardiac repolarisation. Specifically, it calls for a clinical 'thorough QT/QTc study' (typically conducted in healthy volunteers), which is intended to determine whether a drug has a threshold pharmacological effect on cardiac repolarisation, as detected by QT/QTc interval prolongation. The E14 recommendations are generally applicable not only to new drugs that have systemic bioavailability but also to approved drugs when a new dose, route of administration or target population that may result in an increased risk is explored. The guideline provides for exceptions when this study may not be required.Recognising the fractious relationship between ICH E14 and ICH S7B, and the persistence of a number of issues that may require clarity and/or the emergence of other new scientific issues in the future, the ICH Steering Committee has formed an Implementation Working Group that is charged with providing clarity on aspects of the guideline that are ambiguous and responding to issues on which the sponsors are uncertain. This paper provides a commentary on some of the challenges that are likely to be faced by the sponsors of drugs during the next few years of application of these two guidelines. The adoption of these guidelines has left a number of questions unanswered and raised some new ones. When in doubt, the sponsor should seek formal regulatory clarity before making key decisions that may impact further development, assessment and approval of a new chemical entity. Although the goal of developing drugs with much lower torsadogenic potential and without inappropriate restriction in the use (or even rejection) of potentially beneficial drugs is within sight, it is questionable whether the risk of drug-induced pro-arrhythmia will be eliminated completely.     

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

Following reports of death from cardiac arrhythmias with drugs like terfenadine and cisapride, the International Conference for Harmonization formulated a guidance (E14) document. This specifies that all new drugs must undergo a ‘thorough QT/QTc’ (TQT) study to detect drug-induced QT prolongation, a surrogate marker of ventricular tachycardia, especially torsades de pointes (TdPs). With better understanding of data from several completed TQT studies, regulatory requirements have undergone some changes since the E14 guidance was implemented in October 2005. This article reviews the implications of the E14 guidance and the changes in its interpretation including choice of baseline QT, demonstration of assay sensitivity, statistical analysis of the effect of new drug and positive control, and PK-PD modelling. Some issues like use of automated QT measurements remain unresolved. Pharmaceutical companies too are modifying Phase 1 studies to detect QTc liability early in order to save time and resources. After the E14 guidance, development of several drugs that prolong QTc by >5 ms is being abandoned by sponsors. However, all drugs that prolong the QT interval do not increase risk of TdP. Researchers in regulatory agencies, academia and industry are working to find better biomarkers of drug-induced TdP which could prevent many useful drugs from being prematurely abandoned. Drug-induced TdP is a rare occurrence. With fewer drugs that prolong QT interval reaching the licensing stage, knowing which of these drugs are torsadogenic is proving to be elusive. Thus, paradoxically, the effectiveness of the E14 guidance itself has made prospective validation of new biomarkers difficult.This article is part of a themed section on QT safety. To view this issue visit http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2010     

Performance characteristics for some typical QT study designs under the ICH E-14 guidance

The International Conference on Harmonization (ICH) guidance for clinical evaluation of QT prolongation (E14) affected drug development by advocating that a thorough QT study (TQT) be conducted during development to assess the QT prolongation liability of a compound. The ICH E14 Statistics Group shortly thereafter recommended that a noninferiority intersection-union test (IUT) be used to exclude a clinically worrisome QT prolongation. Recent analyses have indicated that the IUT might be overly conservative with respect to excluding QT prolongation. This report assesses the IUT false positive rate for 4 recently conducted TQT trials using simple simulation experiments. Positive TQT study rates ranged from negligible to nearly 60% depending on study design, sample size, and patient status, despite no drug effect. Addition of clinically nonmeaningful QT prolongations (up to 5 milliseconds) increased the positive study rate to 80% for 1 particular study design. Ultimately, these results reveal significant limitations of the IUT with respect to excluding an effect and study interpretation for certain trial designs.     

Early investigation of QTc liability: the role of multiple ascending dose (MAD) study

The International Conference on Harmonization (ICH) guidance note E14 requires a thorough QT (TQT) study to characterize proactively the potential of a new drug to affect cardiac repolarization, as determined by prolongation of the corrected QT (QTc) interval. A typical TQT study is reviewed herein with a discussion on various practical issues concerning the use of a supratherapeutic dose, establishing assay sensitivity, the application of QT rate-correction methods, and restricting analyses of ECGs and plasma samples to key timepoints. We then discuss, and provide examples of, how multiple ascending dose (MAD) study protocols can be modified to integrate robust ECG monitoring and analyses to gather key information provided by a TQT study. Among the main advantages of this approach are the ability to study the ECG effects of a wide range of doses to the maximum tolerated doses, eliminating routine analyses at unnecessary timepoints, making early go-no-go decisions, making phase II studies more efficient and, if necessary, being able to implement rigorous ECG monitoring in populations and pivotal studies of regulatory interest. If clear evidence for the presence or absence of QTc effect is found, the data from a modified MAD study may support a request for a waiver from the requirement to conduct a TQT study. In the event that a TQT study is considered unnecessary, there are obvious significant savings without compromising collection of vital safety data.     

Effect of baseline measurement on the change from baseline in QTc intervals

Phase I thorough QT (TQT) studies are routinely conducted by pharmaceutical companies for all new compounds to satisfy the requirements of International Conference on Harmonisation (ICH) E14 guidance on the evaluation of QTc prolongation. The primary endpoint is the change from baseline in QT interval corrected for heart rate (QTc), and the hypothesis of interest is the noninferiority of drug to placebo. Sometimes, due to the properties of the compound, it becomes necessary to use parallel group designs for TQT studies. In such situations, the effect of the baseline on the change from baseline in QTc becomes an important issue because differing baseline between the drug and placebo groups may not allow for proper estimation of the drug's effect. In this work, we evaluate the effect of baseline on the change from baseline using the placebo data from several TQT studies. Resampling techniques are used to evaluate the impact of differing baselines across groups.     

Effect of Baseline Measurement on the Change from Baseline in QTc Intervals

Phase I thorough QT (TQT) studies are routinely conducted by pharmaceutical companies for all new compounds to satisfy the requirements of International Conference on Harmonisation (ICH) E14 guidance on the evaluation of QTc prolongation. The primary endpoint is the change from baseline in QT interval corrected for heart rate (QTc), and the hypothesis of interest is the noninferiority of drug to placebo. Sometimes, due to the properties of the compound, it becomes necessary to use parallel group designs for TQT studies. In such situations, the effect of the baseline on the change from baseline in QTc becomes an important issue because differing baseline between the drug and placebo groups may not allow for proper estimation of the drug's effect. In this work, we evaluate the effect of baseline on the change from baseline using the placebo data from several TQT studies. Resampling techniques are used to evaluate the impact of differing baselines across groups.     

Statistical assessment of QT/QTc prolongation based on maximum of correlated normal random variables

To establish noninferiority in QT/QTc prolongation of a test drug with respect to either a placebo or an active control, a thorough QT/QTc study is recommended by ICH (ICH E14, ICH 2005) which concerns statistical inference on the maximal time-matched drug effect. The existing statistical methods for assessing such effects suffer either power loss or parameter restriction. In this paper, we propose a new asymptotic test with small sample correction based on distribution of maximum of correlated random variables under both a parallel-group design and a crossover design. Simulations indicate that our proposed test has adequate powers.     

ICH E14:一项新的评价新药研发中药物临床心脏安全性的国际药政法规

2005年5月，有关在临床研究中如何监督新药对心脏安全性的措施，经国际协调会议（ICH）讨论并通过了一项新的工作指南，即ICH协调性三方指南：非抗心律不齐药物的致QT／QTc间期延长和致心律失常的临床评价。本文概述并讨论了该指南要点，以期望对相关新药安全性监督起到一定指导作用。     

Assay sensitivity in “Hybrid thorough QT/QTc (TQT)” study

A concurrent positive control should be included in a thorough QTc clinical trial to validate the study according to ICH E14 guidance. Some pharmaceutical companies have started to use “hybrid TQT” study to meet ICH E14 regulatory requirements since the release of ICH E14 Q&A (R3). The “hybrid TQT” study includes the same treatment arms (therapeutic and/or supratherapeutic dose of investigational drug, placebo, and positive control) with sample size less than traditional TQT studies, but use concentration-QTc (C-QTc) analysis as primary analysis and assay sensitivity analysis. To better understand the statistical characteristics of assay sensitivity with a commonly used positive control – Moxifloxacin - in “hybrid TQT” studies, we examined the original and subsampled moxifloxacin and placebo data from more than a hundred of TQT studies submitted to FDA. The assay sensitivity results are quite consistent between classical E14 analysis and C-QTc analysis using the original datasets. Performance of assay sensitivity in “hybrid TQT” studies using subsampled data depends on number of moxifloxacin subjects, study design (crossover design and parallel design), and C-QTc model. The results presented here can aid the design of future “hybrid TQT” studies.     

Drugs, QT interval prolongation and ICH E14: the need to get it right.

Regulatory concerns on the ability of an ever-increasing number of non-cardiovascular drugs to prolong the corrected QT (QTc) interval and induce potentially fatal ventricular tachyarrhythmias have culminated in initiatives to harmonise internationally the regulatory guidance on strategies by which to evaluate new drugs for this liability. The International Conference on Harmonisation (ICH) has released consensus texts for clinical (ICH topic E14) and non-clinical (ICH topic S7B) strategies as regulatory drafts for wider consultation. Draft ICH E14 calls for a clinical 'thorough QT/QTc study' (typically in healthy volunteers) for new drugs with systemic bioavailability, regardless of the non-clinical data. This indifference to non-clinical data has sparked off a major debate, even among the regulators. The 'thorough QT/QTc study' is intended to determine whether a drug has a threshold pharmacological effect on cardiac repolarisation, as detected by QT/QTc prolongation, and proposes the use of a positive control to validate the study. The guideline recommends exploration of the effect of concentrations that are higher than those achieved following the anticipated therapeutic doses and, consequently, a negative 'thorough QT/QTc study', even in the presence of non-clinical data of concern, will almost always allow standard collection of on-therapy ECGs. The proposed threshold of a 5 ms increase in mean placebo-corrected QTc interval for designating a study as positive for an effect, with all its implications for subsequent development of the drug and its regulatory assessment and labelling, has also generated a controversy. This paper provides an overview commentary on some contentious or ambiguous aspects of draft ICH E14 with a view to stimulating a debate and inviting scientifically supported comments from stakeholders in order to ensure that the application of the ICH E14 strategy, when finalised and adopted, does not result in either restriction in the use (or even rejection) of a potentially beneficial drug or approval of an otherwise hazardous drug without the restrictions required to promote its safe use.     

ICH E14 Q & A (R1) document: perspectives on the updated recommendations on thorough QT studies

The International Conference on Harmonization (ICH) guidance ICH E14 provides recommendations, focusing on a clinical ‘thorough QT/QT_c (TQT) study’, to evaluate the QT liability of a drug during its development. An Implementation Working Group (IWG) was also established to assist the sponsors with any uncertainties and clarify any ambiguities. In April 2012, the IWG updated its June 2008 version of the Questions and Answers document to address additional issues. These include the gender of the study population, a reasonable approach to evaluating QT_c changes in late stage clinical development and the recommended approach to correcting the measured QT interval. This commentary provides our observations and, when appropriate, recommendations, on these issues. We review briefly evidence that suggests that (i) the greater QT effect observed in females is not entirely related to differences in drug exposure and (ii) the Fridericia correction of measured QT interval is adequate for a majority of TQT studies. Until further evidence suggests otherwise, we recommend balanced gender representation in TQT studies, unless warranted otherwise, and for positive studies, subgroup analysis of key data by common demographic variables including the gender and ethnicity. We provide a general scheme for ECG monitoring in late phase clinical trials and consider that while intensive monitoring and centralized reading of ECGs in late phase clinical trials is the norm when a TQT study is positive, there are other circumstances that also call for high quality ECG reading. Therefore, locally read ECGs should only be acceptable as long as accurate high quality ECG data can be guaranteed.     

Early QT assessment – how can our confidence in the data be improved?

Exposure–response (ER) analysis has emerged as an important tool to interpret QT data from thorough QT (TQT) studies and allows the prediction of effects in the targeted patient population. Recently, ER analysis has also been applied to data from early clinical pharmacology studies, such as single and multiple ascending dose studies, in which high plasma concentrations are often achieved. In line with this, there is an on-going discussion between sponsors, academicians and regulators on whether ‘early QT assessment’ can provide sufficiently high confidence in assessment of QT prolongation to replace the TQT study. In this article, we discuss how QT assessment can be applied to early clinical studies (‘early QT assessment’) and what we believe is needed to achieve the same high confidence in the data as we currently obtain from data from the TQT study. The power to exclude a QT_c effect exceeding 10 ms in small sample sizes using ER analysis will be discussed and compared with time-matched analysis, as described in the ICH E14 guidance. Two examples of early QT assessment are shared; one negative and one positive, and the challenge in terms of demonstrating assay sensitivity in the absence of a pharmacological positive control will be discussed. Finally, we describe a recent research proposal, which may generate data to support the replacement of the TQT study with data from QT assessment in early phase 1 studies.     

Testing for positive control activity in a thorough QTc study

The ICH E14 guidance (ICH, 2005) recommend that a concurrent positive control should be included in a thorough QTc clinical trial to validate the study. The ICH E14 guidance (ICH, 2005) state that "The positive control should have an effect on the mean QTc interval of about 5 ms (i.e., an effect that is close to the QTc effect that represents the threshold of regulatory concern, around 5 ms)". This task may be carried out through some statistical tests. The current practice is to test at each time point where QT measurements are collected. This method is usually not efficient. In this article, I discuss two types of statistical procedures. The first one is a local statistical test to make a time-point-specific claim, i.e., to claim a mild QTc effect due to the positive control at some specific time points. A different approach, named as a global test, is also proposed, to make a general claim that the mean difference of the positive control and placebo after baseline adjustment will be about 5 ms without specifying at which time points. An example will be used to illustrate how to apply the two procedures. How to best allocate sample size in a parallel QTc study is also discussed in this paper.     

The use of electrocardiograms in clinical trials: a public discussion of the proposed ICH E14 regulatory guidance

This meeting, jointly sponsored by the FDA, Drug Information Association and Heart Rhythm Society, examined crucial issues on nonclinical and clinical evaluation of the potential of new drugs to prolong the QT interval of an electrocardiogram (ECG). It gathered ～ 350 attendees from pharmaceutical industry, academia, core ECG analysis laboratories, regulatory agencies (FDA, European Medicines Agency, Japanese Ministry of Health, Labour and Welfare, and Health Canada) and the International Conference on Harmonisation (ICH). Key issues discussed included the reliability of the S7B guideline strategy, design and usefulness of the ‘thorough QT/QTc study’ recommended by ICH E14 guideline, choice of 5 ms QTc prolongation as a threshold for regulatory concern, ECG reading, and statistical analysis. This report is restricted to the two main presentations dealing with the predictability of nonclinical tests for clinical outcomes – one defending the prognostic value of nonclinical tests and the other, from the FDA, which casts reservations on the predictive value of nonclinical studies. Commentary on the recent finalisation of ICH S7B and E14 guidelines are also provided.     

The use of electrocardiograms in clinical trials: a public discussion of the proposed ICH E14 regulatory guidance. April 11-12, 2005, Bethesda, MD, USA

This meeting, jointly sponsored by the FDA, Drug Information Association and Heart Rhythm Society, examined crucial issues on nonclinical and clinical evaluation of the potential of new drugs to prolong the QT interval of an electrocardiogram (ECG). It gathered approximately 350 attendees from pharmaceutical industry, academia, core ECG analysis laboratories, regulatory agencies (FDA, European Medicines Agency, Japanese Ministry of Health, Labour and Welfare, and Health Canada) and the International Conference on Harmonisation (ICH). Key issues discussed included the reliability of the S7B guideline strategy, design and usefulness of the 'thorough QT/QTc study' recommended by ICH E14 guideline, choice of 5 ms QTc prolongation as a threshold for regulatory concern, ECG reading, and statistical analysis. This report is restricted to the two main presentations dealing with the predictability of nonclinical tests for clinical outcomes--one defending the prognostic value of nonclinical tests and the other, from the FDA, which casts reservations on the predictive value of nonclinical studies. Commentary on the recent finalisation of ICH S7B and E14 guidelines are also provided.     

Assessing QT/QTc interval prolongation with concentration-QT modeling for Phase I studies: impact of computational platforms,model structures and confidence interval calculation methods

Modeling the relationship between drug concentrations and heart rate corrected QT interval (QTc) change from baseline (C-?QTc), based on Phase I single ascending dose (SAD) or multiple ascending dose (MAD) studies, has been proposed as an alternative to thorough QT studies (TQT), in assessing drug-induced QT prolongation risk. The present analysis used clinical SAD, MAD and TQT study data of an experimental compound, AZD5672, to evaluate the performance of: (i) three computational platforms (linear mixed-effects modeling implemented via PROC MIXED in SAS, as well as in R using LME4 package and linear quantile mixed models (LQMM) implemented via LQMM package; (ii) different model structures with and without treatment- or time-specific intercepts; and (iii) three methods for calculating the confidence interval (CI) of QTc prolongation (analytical and bootstrap methods with fixed or varied geometric mean concentrations). We show that treatment- and time-specific intercepts may need to be included into C-?QTc modeling through PROC MIXED or LME4, regardless of their statistical significance. With the intersection union test (IUT) in the TQT study as a reference for comparison, inclusion of these intercepts increased the feasibility for C-?QTc modelling of SAD or MAD to reach the same conclusion as the IUT analysis based on TQT study. Compared to PROC MIXED or LME4, the LQMM method is less dependent on inclusion of treatment- or time-specific intercepts, and the bootstrap CI calculation methods provided higher likelihood for C-?QTc modeling of SAD and MAD studies to reach the same conclusion as the IUT based on the TQT study.     

全面QT研究的临床试验设计

药物导致的心电图QT/QTc间期延长,虽然发生率不高,但潜在危险性大,严重的可诱发室性心律失常甚至猝死。2005年5月,人用药品注册技术要求国际协调会正式颁布了《非抗心律失常药物潜在导致QT/QTc间期延长和心律失常的临床评价指南》(E14)。本文根据该指南及从大量已完成的研究中总结的经验讨论全面QT研究的临床试验设计要点,以期对今后中国的相关研究提供有益的指导。     

Statistical Issues of QT Prolongation Assessment Based on Linear Concentration Modeling∗

The ICH (2005 ICH ( 2005 ). ICH (E14) Guidance. The Clinical Evaluation of QT/QTc Interval Prolongation and Proarrhythmic Potential for Nonantiarrhythmic Drugs. International Conference on Harmonization, May 2005, in Geneva, Switzerland . [Google Scholar]) defined drug-induced prolongation of QT interval, i.e., the duration of depolarization and repolarization of ventricles, as evidenced by an upper bound of the 95% confidence interval around the mean effect on QTc (QT corrected for heart rate) of 10 ms. Furthermore, it defined that a negative thorough QT/QTc study is one in which the upper bound of the 95% one-sided confidence interval for the largest time-matched mean effect of the drug on the QTc interval excludes 10 ms. This objective leads to the application of intersection-union tests by testing the mean difference between test treatment and placebo of QTc change from baseline at each of the matched time points at which the observations are collected. The nature of the higher false positive rate due to more observational time points leads to the concern of study efficiency. Based on the concept of clinical pharmacology, a concentration-response modeling approach is often adopted to assess the prolongation size of QTc interval induced by a drug without carefully examining the validity of the assumptions involved. In most of the applications, the model is assumed either to be linear, log-linear, or logistic. The supporter of the modeling often emphasizes the advantage of power improvement and reduction in estimation error. However, it has been often pointed out by statisticians and pharmacologists that modeling under an invalid uniformity assumption across study population often leads to severe bias in testing and estimation. In this article, we examine data sets of New Drug Applications to illustrate the bias and lack of validity of the linearity assumptions.     

Scientific white paper on concentration-QTc modeling

The International Council for Harmonisation revised the E14 guideline through the questions and answers process to allow concentration-QTc (C-QTc) modeling to be used as the primary analysis for assessing the QTc interval prolongation risk of new drugs. A well-designed and conducted QTc assessment based on C-QTc modeling in early phase 1 studies can be an alternative approach to a thorough QT study for some drugs to reliably exclude clinically relevant QTc effects. This white paper provides recommendations on how to plan and conduct a definitive QTc assessment of a drug using C-QTc modeling in early phase clinical pharmacology and thorough QT studies. Topics included are: important study design features in a phase 1 study; modeling objectives and approach; exploratory plots; the pre-specified linear mixed effects model; general principles for model development and evaluation; and expectations for modeling analysis plans and reports. The recommendations are based on current best modeling practices, scientific literature and personal experiences of the authors. These recommendations are expected to evolve as their implementation during drug development provides additional data and with advances in analytical methodology.