Cardiovascular (CV) parameters such as blood pressure (BP), electrocardiogram (ECG), and heart rate (HR) are routinely assessed in non-rodent toxicology studies, yet measurement quality varies by methodology—namely telemetry (implanted or jacketed) versus restraint-based techniques. This analysis examined how measurement methods affect baseline CV values and sensitivity to drug-induced effects. Data from three sources were analyzed: 495 toxicology studies from seven pharmaceutical companies (2015–2023), FDA recently approved drugs (47 NCEs, 26 NBEs in 2022–2023), and two major CROs (2020−2023). Studies involved dogs, minipigs, or non-human primates with dosing durations up to 52 weeks. Additional literature, proprietary data, and questionnaire informed baseline comparisons and statistical and pharmacological sensitivity. In our toxicology datasets, ECG was commonly collected, whereas BP was not. The selection of ECG and BP recording methods was mostly sponsor-dependent. Telemetry was predominantly used in short-duration studies; restraint-based snapshot methods were common in longer studies. Restraint consistently increased baseline BP and HR values and variability. QTc correction methods under restraint were inconsistent across sponsors/CROs. Statistical analysis was common with telemetry but infrequent under restraint. Case examples show that telemetry detected clinically-relevant BP or QTc changes; however, restraint methods usually did not. These findings demonstrate that restraint methods increase baseline values and variability, reducing pharmacological and statistical sensitivity to detect CV effects. Current practices appear driven by sponsor convention as well as scientific rationale. As ICH S7A/S7B evolve, re-evaluation of CV monitoring methods is warranted to enhance scientific rigor, regulatory alignment, and 3Rs compliance in nonclinical safety assessment.

Cardiovascular monitoring in non-rodent species remains a key component of regulatory safety assessment and translational risk evaluation in pharmaceutical development. Electrocardiogram, blood pressure, and heart rate measurements are central to identifying functional cardiovascular liabilities and informing first-in-human decisions. However, approaches used to collect these endpoints in repeat-dose toxicology studies remain heterogeneous across sponsors and study designs, with important consequences for data quality and interpretation.This review examines whether cardiovascular endpoints are required in every repeat-dose non-rodent toxicology study and evaluates the strengths and limitations of currently used methodologies. A review of ICH guidance indicates that cardiovascular monitoring is not explicitly mandated in all repeat-dose studies, supporting a context-of-use approach in which monitoring is determined by pharmacology, modality, exposure profile, and the totality of evidence. Emerging cross-industry surveys, retrospective analyses, and case studies further show that recording methodology is a major determinant of sensitivity, interpretability, and regulatory value.Restraint-based snapshot methods are limited by handling stress and, in some cases, sedation-related artefacts, which can alter baseline physiology, increase variability, and reduce the ability to detect clinically relevant effects such as QTc prolongation and hemodynamic changes. In contrast, telemetry-based approaches, including jacketed and implanted systems, provide continuous recordings in freely moving animals, enable circadian and exposure–response analyses, and generate more physiologically relevant datasets.Telemetry should therefore be considered the preferred standard for non-rodent cardiovascular monitoring when such assessment is warranted. Future progress will depend on broader standardization, refinement of telemetry technologies, advanced analytics, and integration with new approach methodologies.

New approach methodologies (NAMs) originated in chemical hazard assessment, where two forces operate together: the scale of characterizing many substances, and a long-standing ethical and legal commitment to replacing animal testing. Drug development is weighted differently. It is a translational and decision problem applied to small sets of compounds at pharmacologically active exposures. As NAMs capabilities have expanded, the two domains have been conflated, and framing NAMs against animal studies as a binary choice risks undermining both. The so-called translatability crisis is not a single problem with a single solution. Clinical attrition reflects gaps in mechanistic understanding, exposure-irrelevant study designs, underpowered analyses, and survivorship bias that obscures the screening value of nonclinical studies. Addressing these challenges requires an integrated strategy in which the choice of platform, the design of endpoints, and the rigor of validation are governed by a clearly defined context of use. A biologically relevant model is defined not by its type but by its fitness for the purpose it serves. We argue for a patient-centered nonclinical paradigm that combines animal and non-animal approaches, aligned with recent FDA, NIH, and EMA direction, and note that both domains converge on the same non-dogmatic conclusion.

Telemetered models are essential tools in cardiovascular safety studies, but spontaneous activity can confound heart rate (HR) measurements. To isolate direct drug effects, we applied a “one-step” correction method (previously used for QT interval adjustment) to HR. This approach improves sensitivity and may reduce the number of animals needed to detect treatment-related changes. We hypothesize that it will increase statistical power and better detect small HR differences.We analyzed a historical study of 9 Sprague Dawley (SD) rats implanted with PA-C4 telemeters with 80 days of recordings. Data were collected for 10 s every 10 min. Least significant differences (LSDs) were determined by subtracting the lower confidence interval (CI) from the upper CI and dividing by 2. Group sizes of 3, 4, 6, and 8 were analyzed. A separate 48-day study of 17 Dahl S rats implanted with HD-S10 telemeters, treated with semaglutide at 0.1 mg/kg SC (N = 9) or vehicle (saline, N = 8) daily, was analyzed to evaluate treatment effect.The one-step method produced smaller LSD values compared to the conventional method. For group sizes of 8, average LSDs were 3 ± 0.001 BPM versus 15 ± 1 BPM for the one-step and conventional methods, respectively. Across all two-day and animal combinations, one-step LSDs averaged 3 ± 0.1 BPM compared to 14 ± 1 BPM with the conventional method. Weekly averages supported this advantage (1 ± 0.001 BPM vs. 15 ± 3 BPM). In the semaglutide-treated group, detected HR differences were similar (65 ± 0.5 BPM with one-step vs. 64 ± 2 BPM with conventional method), but LSDs were lower with one-step (1 BPM vs. 19 BPM). Super-interval (2–8 h) analyses at a group size of 8 demonstrated decreasing LSDs (median ± SD) with longer intervals: one-step yielded 11 ± 2, 8 ± 1, 6 ± 0.6, and 6 ± 0.5 BPM, while the conventional method returned 20 ± 4, 17 ± 3, 16 ± 3, and 16 ± 2 BPM, respectively.The one-step correction method enables more precise detection of drug-induced HR changes by accounting for activity-related variability, offering greater sensitivity. This supports the use of smaller group sizes while maintaining statistical power, reducing unnecessary animal use in preclinical studies.

The ICH S7A guideline on safety pharmacology has remained unchanged since its inception in 2000, fulfilling its crucial role in safeguarding clinical trial participants and patients. However, in the meanwhile there has been significant scientific and technological advancements in drug safety science, a paradigm shift in the drug discovery and development process, and a continuously evolving regulatory landscape, that led to the recommendation to revisit, adapt and evolve the ICH S7A guideline (Valentin & Leishman, 2023, 2025). A revision of the guidance would imply opening an ICH process, the first step consists in the development of a ‘concept paper’. In that context, a survey has been developed to determine which elements, if any, of the ICH S7A guideline should be revised. Sixty-five (65) responses were obtained from industry representatives of companies affiliated to EFPIA, JPMA or PhRMA. Overall, there was a large support to revisit most of the pillars originally identified via a ‘revision’ or a ‘Q&As’ ICH procedure. These include revisiting the ‘core battery’ assessment (58 to 68%), the adversity concept (77%), the modality agnosticism of the guideline (89%), the in vitro secondary pharmacology component (85%), the integrated risk assessment principles (75%), and the inclusion of safety pharmacology endpoints in general toxicology studies (72%). However, there were fewer than 50% positive responses to revisiting the timing of the studies with respect to drug development stages and the validation or qualification principles to be applied to novel assays and models (<50% of positive responses). Notably, the majority of respondents viewed the ‘core battery’ studies as valuable, whereas ‘supplemental’ studies were less frequently seen as contributing additional value. Moreover, many indicated that they routinely perform safety pharmacology studies outside of these predefined categories—such as exploratory, mechanistic, or investigative studies. Overall, there was a large agreement between the responses from all territories. The survey results captured which elements of the ICH S7A guideline should be revised to help the development of a formal ICH concept paper.

Core battery cardiovascular (CV) parameters [e.g., arterial blood pressure (BP), electrocardiogram (ECG), heart rate (HR)] are recorded in non-rodent safety pharmacology and toxicology studies. Data is used to support drug development in accordance with regulatory guidelines (e.g., ICH S7A. S7B S6, S9 and M3(R2)). However, the quality of measurements varies based on the methods used, ranging from restraint (unacclimated) to telemetry (implanted or jacketed)-based recordings. This analysis reviewed and compared current practice regarding methodological approaches applied to the acquisition of CV data in repeat-dose non-rodent toxicology studies. The data was sourced from 7 Sponsors, 2 major CROs and FDA regulatory drug approvals. Studies evaluated data acquired from dogs or non-human primates (NHP) with study durations up to 52 weeks. A literature-based search and proprietary published examples were used to establish baseline CV values and to ascertain the ability of the different methodologies used to detect drug-induced CV effects. The literature search provided evidence that baseline CV (BP and HR) values are consistently higher in restrained versus non-invasive telemetry methods. Moxifloxacin and proprietary drugs showed that hERG-mediated QTc prolongation was detected in the clinic and in NHP or dog studies using telemetry methods but not in restrained surface‑lead snapshot methods. Data showed that the ECG is collected in most repeat-dose toxicology studies, but BP is usually not collected. Overall, telemetry-based methods account for 61 % of ECG recordings; while much less frequent, restraint-based methods are used for 44 % of BP recordings, when collected. The choice and usage of collection methods is highly sponsor-dependent, with restraint-based methods for individual sponsors ranging from 0 to 100 %. Data showed that telemetry-based methods are predominately used in short-duration studies for drug safety assessments, but restraint-based snapshot methods are used in longer-duration studies. The data compiled thus far serves as a basis to consider CV collection methods used in toxicology studies and to develop recommendations on the measurement of ECG and BP in non-rodent species in support of regulatory safety assessment studies.

Small, relatively insensitive studies can be useful in safety assessment when multiples of the therapeutic clinical concentration are tested. This is a fundamental principle in safety testing in animals which is equally valid for early clinical evaluations in healthy volunteers. It is often less practical to increase the number of test subjects than to increase the exposure tested. Both, when combined with the analysis method, can have an impact on the sensitivity to detect an effect. The objective is that the relationship between statistical power, analysis method, number of animals and exposure multiple explored can be illustrated using the example of QTc assessment in animals. The statistical power to detect an effect on the electrocardiogram QTc interval in nonhuman primates (NHP) for different analyses methods was known. The concentration-QTc relationship was also known for reference agents in NHP. Lastly, the critical concentration associated with a 10 ms QTc interval change in man was known for these same reference agents. This information was combined to illustrate how doubling the number of NHP used or increasing the exposure tested would support a conclusion concerning the presence or absence of an effect on the QTc interval for a test agent. In NHP, the most sensitive analysis methods have >80 % power (at p < 0.05) to detect an effect of the reference agent at the critical concentration using only 4 animals. Less sensitive techniques can detect an effect with the same power when either more animals are used or where higher multiples of the critical concentration are tested. This illustrates the principle that even with only 4 animals and an insensitive technique an effect can be detected provided higher exposures are tested. Conversely, a study using more animals, or a more sensitive analysis needn't require a higher exposure in animals to exclude an effect in man. Rather than focusing on a fixed QTc threshold sensitivity regardless of experimental design these analyses demonstrate that investigators have the flexibility to use the simplest available combination of exposures, animal numbers and analysis to achieve an effective QTc assessment.

Quantitative QTc assessment in toxicology studies can use one of two techniques, either continuous telemetry recording in ambulatory animals or short snapshots of electrocardiograms recorded using multilead electrodes in restrained animals. QTc assessments can augment clinical QTc data in regulatory submissions provided both the statistical and pharmacological sensitivity can be demonstrated. Analyses in dogs (N = 24) used both jacketed external telemetry (ET) and short segment or 'snapshot' (SS) multilead recordings in separate phases. Three groups (moxifloxacin, and two doses of ondansetron) were compared to a vehicle group. In phases 1 and 2, one group received moxifloxacin (30 mg/kg), two received doses of ondansetron (3 and 10 mg/kg), and the last received vehicle (0.5 % (w/v) methylcellulose in deionized water) in a parallel group study design. The third phase of the study involved the original 12 male dogs receiving all treatments in a randomized triple Latin square design. ET (n = 6/group) detected a significant effect on QTc of moxifloxacin for all but one hour of the postdose period and detected an effect at fewer timepoints with ondansetron in a dose- and exposure-dependent manner. QTc prolongation at a single timepoint was significant for both the lower dose of ondansetron and moxifloxacin using SS. SS did not detect any significant QTc effect at the higher dose of ondansetron. In the cross-over phase (ET only), moxifloxacin significantly prolonged the QTc interval through all but one hour of the post dose period. Low dose ondansetron did not significantly prolong the QTc interval while there was a small dose-dependent effect with isolated time points being significant with the higher dose. The least significant differences detectable were approximately 9 (ET), 17 (SS) and 5 ms (ET with Latin square) for the three phases, respectively. These analyses demonstrate the statistical and pharmacological sensitivity of the techniques commonly used in large animal toxicology studies. Overall, QTc assessment using telemetry is the more sensitive and consistent technique and is a model sufficiently sensitive to supplement clinical QTc assessment.

The core ICH S7B in vitro assay is a hERG assessment which has associated best practice recommendations. Three reference agents are being used to compare margins based on concentrations associated with 10 ms QTc prolongation in man. The objective of the current analyses was to compare the margins for best practice hERG patch-clamp data with those for other in vitro assessments. The unbound critical concentrations shared as part of the Training Materials were used as the denominator throughout. The numerators were: the hERG IC50 generated in a study conforming to current best practice guidance, the pKi from published dofetilide-binding data, the concentrations associated with either published rate corrected APD90 prolongation in isolated IPD-derived human cardiomyocytes, or with a 25 ms change in APD90 in human ventricular trabeculae tissue. The respective margins for dofetilide, moxifloxacin and ondansetron in the patch-clamp study were 45, 32 and 4.2. The dofetilide-binding displacement pKi, gave margins of 11, 15 and 10. In isolated cardiomyocytes the margins were 0.5, 5.2 and 1.3. In human trabeculae tissue the margins were 14, 4.5 and 9. There is an underlying assumption that for selective hERG blocking drugs the amount of hERG block (and associated hERG margin) would be similar for the same 10 ms change in QTc. The consistent margin determined using the dofetilide-binding displacement pKi and the concentration associated with a 25 ms APD90 prolongation in human trabeculae would tend to support that assessment. There was more variability in isolated cardiomyocytes where there was an 11-fold difference between dofetilide and moxifloxacin margins while the ondansetron margin lay in between these margins. The hERG patch-clamp study had skewed variability with a margin for ondansetron 11-fold and 8-fold different from the margins for dofetilide and moxifloxacin, respectively. The small margin for ondansetron caused wider confidence intervals for the pooled margin of 18-fold. Overall, these data suggest that any of these assays might realistically be used to predict a QTc prolongation in man. The hERG patch-clamp study is the required study. Where there are ‘ondansetron-like’ blocking characteristics an additional assay may be warranted to clarify the prediction.

Reliable prediction and prevention of adverse drug reactions (ADRs) remains a key challenge in the development of new medicines. Advanced mathematical and computational modelling approaches, which incorporate cutting-edge mechanistic understanding of ADRs in concert with systematically collected data addressing knowledge gaps, are integral components of model-informed drug discovery and development (MID3). These approaches provide a precise, quantitative framework for predicting and mitigating safety risks in the earliest phases of drug development. Here, we highlight recent developments in the burgeoning field of quantitative systems toxicology (QST), including insights into the current state-of-the-art, as well as outcomes from the Innovative Medicines Initiative (IMI) 2 TransQST project. QST models that describe the disruption of cardiovascular, gastrointestinal, hepatic and renal physiological functions following drug exposure are presented, along with recommendations for their application in drug discovery and development.

INTRODUCTION:Cardiovascular (CV) parameters1 such as blood pressure (BP), electrocardiogram (ECG), and heart rate (HR) are recorded in non-rodent non-clinical safety studies to support drug development. However, measurement quality varies depending on the methodology used, including restraint-based or telemetry (implanted or jacketed) techniques. Measurement quality, in this context, refers to the sensitivity and reliability of CV measurements in affecting baseline values of measured CV parameters and in detecting pharmacological effects. This retrospective multifaceted analysis evaluated the impact of recording methods on baseline CV parameters and their statistical and pharmacological sensitivities in detecting drug-induced CV effects. METHODS:Data were collected from three sources: (i) 495 studies from seven pharmaceutical sponsors (2015-2023), (ii) FDA-approved drugs (47 NCEs, 26 NBEs from 2022 to 2023), and (iii) two major CROs (2020-2023). Studies were conducted in dogs, non-human primates (NHP), or minipigs, with treatment durations of up to 52 weeks. Additionally, literature-based and proprietary data were analyzed to assess baseline CV values and methodology sensitivity. A survey was conducted to evaluate statistical analysis practices in these studies. RESULTS:All 3 datasets showed that the ECG is collected in most repeat dose toxicology studies, but not BP; the findings were largely independent on the modality (i.e., NCE versus NBE) or the indication (i.e., oncology vs. non-oncology). The choice and usage of ECG and BP methods is highly sponsor-dependent, with restraint-based methods for individual sponsors ranging from 0 to 100 %. FDA data showed that telemetry-based methods are predominantly used in short, single dose toxicology/safety pharmacology studies for NCEs. Subsequent studies of longer duration employ predominantly restraint-based snapshot methods. CRO data showed that approximately 30 % of toxicology studies do not include ECGs; however, when an ECG is recorded it is primarily collected in restrained animals using a snapshot approach. BP is infrequently recorded, regardless of methodology, in repeat dose toxicology studies. The de novo analysis and literature-based search showed that baseline BP/HR values were highly variable with consistently higher means under restraint compared to telemetry methods. The root mean square errors for BP/HR were larger under restrained conditions, in both species. Under restrained conditions, the use of fixed formulae for HR-corrected QT resulted in inconsistent QTc values across sponsor and CROs. The survey showed that statistical analysis of ECG/BP data was infrequently performed under restrained conditions in contrast to telemetry-based methods. Proprietary and published case studies showed that drug-induced BP elevation or QTc prolongation observed clinically and in NHP or dog using telemetry were not reliably detected under restraint-based conditions, highlighting limitations of RB methods in CV safety evaluation. The data illustrate that animal restraint reduces the pharmacological and statistical sensitivities to detect CV effects. CONCLUSIONS:ECG and BP recording methods vary based on sponsor preference, experience and/or institutional practices in addition to scientific rationale. Literature and case studies confirm the limitations of restraint-based methods. As ICH S7A/S7B evolve, revisiting CV assessment practices is necessary to align with scientific, technological, regulatory, and 3Rs considerations, ultimately improving best practices for regulatory safety assessment.

Released in 2022, the FDA's draft guidance “Assessment of Pressor Effects of Drugs”, proposes that a dedicated clinical study for chronic use drugs should be powered to rule out a potential systolic arterial blood pressure (BP) increase of 3 mmHg over 24 h. Given the resource commitment of clinical studies, sensitive nonclinical prediction of potentially meaningful BP increases would be valuable. This study aimed to determine the utility of long-term rat studies for detecting acute and chronic blood pressure changes. We hypothesized that studies using rats have adequate stability and variability to detect BP changes ≥3 mmHg over several weeks. Available data from a historic rodent assessment of 80 days duration (N = 9) in vehicle treated Sprague Dawley rats was used. The data were assessed for minimal detectable differences (MDDs), least significant differences (LSDs), and changes from baseline for all BP measures in light and dark 12 h, days, and weeks. Day 15 was used as the reference day and Day 43 as the comparison for day-to-day and light and dark changes from baseline to simulate a 4-week study with a week-long baseline assessment. In week comparison, week 2 was compared to week 5. A one-way t-test was conducted against an assumed mean difference of 0 to evaluate for significance. Study average difference from baseline for the dark cycle were 1.80 ± 1.42 (mean ± standard deviation), 1.99 ± 1.34, and 1.86 ± 1.25 mmHg for diastolic (Dia), systolic (Sys), and mean arterial pressure (MAP), respectively. Light cycle differences were 0.54 ± 1.23, −0.04 ± 1.101, and 0.143 ± 0.91 mmHg for Dia, Sys, and MAP . Day-to-day differences of 1.21 ± 1.29, 0.89 ± 1.12, and 0.931 ± 1.01 mmHg for Dia, Sys, and MAP were seen. Week-to-week differences were − 2.55 ± 1.47 mmHg for Sys, 2.30 ± 1.29 mmHg for MAP, and 1.87 ± 1.22 mmHg for Dia. Results were not significantly different from 0. Overall, rats demonstrated small insignificant changes from baseline in their blood pressure measures across a longitudinal study. The low variability observed was sufficient to encourage further evaluation of the minimal detectable differences which is currently underway.

Life supportive cardiovascular (CV) parameters [e.g., arterial blood pressure (BP), electrocardiogram (ECG), heart rate (HR)] are recorded in non-rodent safety pharmacology and toxicology studies and data are used to support pharmaceutical drug development in accordance with several guidelines (e.g., ICH M3, S6, S7, S9). Various methodological approaches are used to collect CV parameters on toxicology studies, including fully implantable telemetry, non-invasive jacket telemetry, and short-duration restraint-based measurement from surface ECG leads and a blood pressure cuff, but their robustness and applicability domain differ widely. The challenge of using conscious animals, especially non-human primates, is that arousal behavior, locomotion, body temperature, and sympathetic activation are significant sources of variability that impact CV parameters, thus telemetry methods are the preferred approach. Historically, toxicology studies have incorporated short-duration restraint methods (manual; chemical sedation) to collect brief periods (“a snapshot at one timepoint”) of CV endpoints in a large number of non-rodents (N ≥ 24) after repeat dosing. Non-rodent species, however, demonstrate increased BP and HR in response to room entry and/or manual restraint, which confounds the interpretation of drug-related effects. Published case examples and company experiences indicate that CV waveforms collected under restraint are of low quality, can vary based on body position and sensor placement (skin electrode; pressure cuff), as well as the type of sedative and dose used. In addition, the data captured can be misleading or incongruent with CV safety pharmacology findings in the same animal species. As a result, restraint-induced stress lowers the sensitivity to detect CV changes as measured over a short-duration and has a higher probability for false negative findings. Although functional CV evaluations in restrained animals have been included in toxicology studies for decades, there is no industry consensus on methods, assay performance, or value (translation) for risk assessment. This communication will review the available literature and leverage pharmaceutical and Contract Research Organization (CRO) experiences, and propose recommendations, with an emphasis on short-duration techniques, from the ICH E14/S7B Industry Support Group with the aim to identify how, when, and if short term restraint-based CV data are valuable for nonclinical safety assessment.

Nonclinical QTc studies can augment clinical QTc assessments in regulatory submissions provided they are of sufficient quality and sensitivity. Both the statistical performance and species translation play a role in determining the sensitivity of the model. The current analyses examine the effects of dofetilide or vehicle on the QT interval in nonhuman primate (NHP; n = 16) using a one-step estimated marginal means method where both treatment and animal ID are used in regression models to avoid a separate rate correction step, in comparison to other commonly utilized methods. The doses of dofetilide were chosen to span a threshold dose with exposure only just exceeding the concentration associated with 10 ms QTc prolongation in man, to a dose where exposures exceed the Emax for QTc prolongation. The primary objective was an evaluation of which doses and exposures can be detected as eliciting a statistically significant change in QTc. A group size of 8 for cross-over analysis was insufficient to detect, as statistically significant, the effects of the threshold dose of 0.01 mg/kg dofetilide using common correction and statistical analysis methods and hourly time intervals. Higher doses were all detected as causing a statistically significant effect using the same techniques. The 'One-Step' method was able to detect as statistically significant effects at all doses of dofetilide across a wide range of time and exposure. There were also temporal differences between the mean effects observed using the common and 'One-Step' methods. Preliminary concentration-QTc assessment suggests a higher maximum prolongation in concentration QTc with the 'One-Step' method. Furthermore, this analysis suggests that at exposures associated with a 10 ms QTc prolongation in man a 10 ms prolongation is also observed in NHP. The observed ED50 concentration (0.85 ng/ml unbound) is close to that described in man (0.98 ng/ml). These analyses demonstrate the statistical sensitivity of the 'One-Step' method of QTc assessment in NHP. The pharmacological sensitivity was also demonstrated and a detection threshold of 10 ms was consistent in terms of exposure between NHP and man. Overall, QTc assessment using the 'One-Step' method in NHP is a robust and sensitive model to supplement clinical QTc assessment.

Jacketed external telemetry (JET) is an important technology allowing access to continuous ambulatory electrocardiogram data in settings in addition to standalone cardiovascular safety pharmacology studies such as GLP toxicology studies. In developing oncology therapeutics under ICH S9 it may also be the case that QTc data collected during toxicology studies is the only in vivo data available to support an integrated risk assessment under the new ICH E14 Q6.1. The current analyses compared JET in freely moving dogs with more conventional ‘snapshot’ collections in restrained, recumbent animals for the same group of 24 beagle dogs (12 M, 12F). The treatments tested were vehicle, ondansetron (3 and 10 mg/kg), and moxifloxacin (30 mg/kg). A parallel study design (3 animals per sex per group) was used in the comparison of JET and ‘snapshot’ collection. In a subsequent phase of the study the 12 male dogs were rotated through the other treatments to create a Latin square crossover analysis. The higher dose of ondansetron achieved Cmax exposures consistent with the clinical critical concentration associated with a 10 ms QTc prolongation. The tested dose of moxifloxacin was the same as that tested in previous studies and achieved a Cmax concentration ~ 3-fold the critical concentration associated with a 10 ms QTc prolongation and had sustained exposure throughout the 24 h telemetry collection period. No treatment related QTc effects were detected using ‘snapshot’ data collection. The small heart rate increase following moxifloxacin detected using JET was not detected in the ‘snapshot’ analysis. Statistically significant, treatment-related QTc prolongation was detected for both doses of ondansetron and moxifloxacin in the parallel and the cross-over JET data analyses. The study-specific least significant difference was 7.1 ms and 2.6 ms for these analyses, respectively. JET data collection and analysis in a parallel toxicology-like design proved sensitive enough to support ICH E14 Q6.1 integrated risk assessment. Conventional ‘snapshot’ analysis was not sufficiently sensitive to detect a treatment-related effect even for modest multiples of the human critical concentrations.

In preclinical cardiovascular safety pharmacology studies, it is often not viable to predict a concentration/QT prolongation relationship due to a lack of robust pharmacokinetic (PK) data or physiologic effects on telemetry data. As the QT-RR relationship changes with drug plasma concentration and factors like body temperature, it becomes difficult to determine the instantaneous concentration-QTc relationship. Currently, robust testing in telemetered animals is standard for determining this relationship in preclinical studies. However, we can relate the average concentration over specific time periods to the average corrected QT interval. In the present study, it is hypothesized that averaging plasma concentration over time creates a simple, and accurate evaluation of the concentration-QTc without the need for expansive PK and PD data. Cardiovascular telemetry studies were conducted in dogs (n = 8, cross-over) and non-human primates (NHP; n = 48 cross-over). Pharmacokinetic samples were taken on separate days in both studies. Average plasma concentrations for specific time intervals (CAverage0-X) were calculated for moxifloxacin in dogs (30 mg/kg, po) and non-human primates (NHP; 80 mg/kg, po) using PkAnalix modeling software (Lixoft). The average QTc effect was then calculated for the same intervals using a linear regression of all the QT and RR data from the 0-X hour interval. The concentration and QTc data were used to model the concentration-QTc effect. In moxifloxacin-treated NHPs, a 10.9 ± 0.06 ms (mean ± SEM) change in QTc was detected at approximately 1.5× the plasma concentration known to cause a 10 ms QT change in man, the critical concentration. The concentration QTc relationship for a sham treatment did not detect a change up to 3× the critical concentration. Similarly in moxifloxacin-treated dogs, a 16.6 ± 0.1 ms change was detected at 1.7× critical concentration, while only a 0.04 ± 0.1 ms change was seen for sham. Overall, while it is optimal to have expansive PK and QTc data points, it is not absolutely necessary for rigorous concentration-QTc analyses. These analyses demonstrate that a simple concentration QTc model can detect effects at relevant exposures. These findings illustrate a simple and effective way to address key cardiovascular safety pharmacology questions when preclinical drug exposures exceed clinical concentrations. In its simplest form, if the average concentration over 24 h exceeds the clinical exposures by at least 2× then determining the average QTc effect (using all the 24-h QT-RR data) would be sufficient to rule out a QTc effect.

The hERG potassium channel has been a critical focus in drug discovery and development for the past 30 years due to its role in cardiac repolarization and its association with drug‐induced torsade des pointes (TdP). An initial spike in TdP adverse events in the 1990s led to extensive regulatory and pharmaceutical industry efforts to mitigate this risk. The hERG channel, known for its promiscuous binding to various drugs, has unique structural features that contribute to its susceptibility to blockade. The absence of the Pro‐X‐Pro motif in its S6 transmembrane helix results in a wider inner vestibule, allowing diverse drugs to bind. Unique pore‐lining amino acids can facilitate that binding. The hERG margin, defined as the ratio between the hERG IC 50 and the therapeutic unbound plasma concentration, has been a key metric in assessing the risk of QTc prolongation and proarrhythmia. Despite the challenges, advancements in in silico and in vitro screening tools have improved the efficiency of hERG testing. The Comprehensive in vitro Proarrhythmia Assessment (CiPA) initiative has further refined the predictive models for proarrhythmia risk. The regulatory response, including the ICH S7B and E14 guidelines, has provided a framework for integrated risk assessment. The continued vigilance and optimization of compounds to avoid hERG blockade remain crucial in drug development, ensuring patient safety and minimizing the risk of drug‐induced cardiac events.

This work explores the relationship between event prevalence and event observation in the context of a study with a fixed number of subjects. For any given study size, one expects the number of occurrences of a given event to increase as the prevalence of that event increases. We use the Binomial distribution to characterize the likelihood of observing at least one specified event for a fixed sized study over a range of prevalence values. From this, we explore the marginal impact on that likelihood as the study size increases. We present findings regarding the value of prevalence that maximizes the marginal impact of adding one additional subject to a study. We then explicitly characterize the interaction of prevalence and sample size in yielding event observation and provide a vehicle by which study planners may design studies based on risk of non-detection as opposed to traditional power calculations.