Telemetric assessment of social and single housing: Evaluation of electrocardiographic intervals in jacketed cynomolgus monkeys

Method of measuring effects of study procedures in single and pair housed New Zealand White rabbits (Oryctolagus cuniculus)

Social housing of laboratory rabbits is encouraged and thought to improve animal welfare due to the social nature of this species. However, there is limited published information comparing the physiologic and cardiovascular (CV) effects of paired and single housed adult female rabbits in commonly used laboratory caging. This study describes measurement of heart rate, systolic blood pressure, activity level, body temperature and pairing methods in four female New Zealand White rabbits that were previously implanted with M10 cardiovascular telemetry devices. Data was collected in single housed rabbits having no history of social housing while they were undisturbed in the home cage, during restraint, intramuscular injections and intravenous blood collection. The same animals were then placed in compatible pairs and housed in conventional Allentown caging. As expected, we found increased activity in paired rabbits but no significant differences in body temperatures, and CV parameters in single and paired rabbits undergoing the same procedures. These data suggest that paired rabbits can be used for safety pharmacology studies with minimal impact to data, while supporting improved animal welfare.

Strategies to encourage the adoption of social housing during cardiovascular telemetry recordings in non-rodents

The National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) is working with industry to promote social housing during cardiovascular telemetry recordings within non-rodent safety pharmacology and toxicology studies. Following surveys to capture current practice, benefits and concerns to adoption of this refinement (2015 and 2017), a 2018 European workshop shared experience and practical advice to address common barriers such as sensitivity of different study designs and the potential for cross-contamination with test article in socially-housed conditions. A similar number of responses were received to each survey (38 in 2015; 36 in 2017), from biopharmaceutical companies and CROs that perform or outsource non-rodent telemetry studies. Each dataset had different respondents, but 19 facilities provided answers regarding dogs and non-human primates (NHPs) for both surveys. More respondents socially-housed their non-rodents in 2017; increases were apparent for both the non-recording/acclimatisation periods and the telemetry recording periods compared with 2015. However, on recording days only 60, 75 and 89% of respondents from Europe and 25, 14 and 36% of respondents from outside of Europe socially-housed their dogs, minipigs or NHPs respectively. The potential for contamination with test article between animals housed together is considered by some facilities as justification for individual housing during recordings, however, survey data did not support this rationale. Nine organisations provided data on prevalence of vomiting during telemetry studies, showing the risk was moderate for dogs and very low for minipig and NHP. Further, if vomiting did occur, this could be managed effectively with little impact on study outcomes or validity and with careful dose selection, the risk is further diminished. A recent increase in published papers and posters on this topic would suggest many more companies are planning, or have recently implemented, this refinement. The continued willingness of the community to share practical experience and publish validation data may lead to this approach becoming the 'new standard' across the industry in the near future, representing a core component of 'best-practice' recommendations to increase animal welfare whilst maintaining quality data provision for investigational and regulatory purposes.

Detecting drug-induced changes in ECG parameters using jacketed telemetry: Effect of different data reduction techniques

INTRODUCTION

Continuous cardiovascular data is routinely collected during preclinical safety assessment of new medicines. This generates large datasets, which must be summarised to analyse and interpret drug effects. We assessed four methods of data reduction of continuous electrocardiogram (ECG) data and examined the impact on the statistical power of the assay.

METHODS

Continuous ECG data were collected from a validation study in 6 cynomolgus monkeys using jacketed telemetry. Animals received either vehicle or vehicle followed by ascending doses of moxifloxacin each on a different dosing day. Recordings made for 25h on each dosing day were reduced to discrete time-points using: 1-min average snapshots, 15-min average snapshots, large duration averages (0.5-4h) or super-intervals (3.5-9h averages).

RESULTS

There was no difference in the ability to detect moxifloxacin-induced QTc prolongation between the 1- and 15-min snapshots and the large duration averages data reduction methods (minimum detectable change in QTca of 20, 17 and 18ms, respectively at 80% power). The super-intervals method detected slightly smaller changes in QTc (15ms), but did not detect a statistically significant increase in QTc after the lowest dose of moxifloxacin, in contrast to the other methods. There were fewer statistically significant differences between dosing days in animals given vehicle when the large duration averages and super-interval reduction techniques were used.

DISCUSSION

There is no marked difference in the power of detection of drug-induced ECG changes in cynomolgus monkeys when using either small duration average or large duration average data reduction techniques. Use of larger duration averages or super-intervals may facilitate data interpretation by reducing the incidence of spurious significant differences that occur by chance between dosing days.

Opportunities to Apply the 3Rs in Safety Assessment Programs

Before a potential new medicine can be administered to humans it is essential that its safety is adequately assessed. Safety assessment in animals forms an integral part of this process, from early drug discovery and initial candidate selection to the program of recommended regulatory tests in animals. The 3Rs (replacement, reduction, and refinement of animals in research) are integrated in the current regulatory requirements and expectations and, in the EU, provide a legal and ethical framework for in vivo research to ensure the scientific objectives are met whilst minimizing animal use and maintaining high animal welfare standards. Though the regulations are designed to uncover potential risks, they are intended to be flexible, so that the most appropriate approach can be taken for an individual product. This article outlines current and future opportunities to apply the 3Rs in safety assessment programs for pharmaceuticals, and the potential (scientific, financial, and ethical) benefits to the industry, across the drug discovery and development process. For example, improvements to, or the development of, novel, early screens (e.g., in vitro, in silico, or nonmammalian screens) designed to identify compounds with undesirable characteristics earlier in development have the potential to reduce late-stage attrition by improving the selection of compounds that require regulatory testing in animals. Opportunities also exist within the current regulatory framework to simultaneously reduce and/or refine animal use and improve scientific outcomes through improvements to technical procedures and/or adjustments to study designs. It is important that approaches to safety assessment are continuously reviewed and challenged to ensure they are science-driven and predictive of relevant effects in humans.

Social housing of non-rodents during cardiovascular recordings in safety pharmacology and toxicology studies

INTRODUCTION

The Safety Pharmacology Society (SPS) and National Centre for the Replacement, Refinement & Reduction of Animals in Research (NC3Rs) conducted a survey and workshop in 2015 to define current industry practices relating to housing of non-rodents during telemetry recordings in safety pharmacology and toxicology studies. The aim was to share experiences, canvas opinion on the study procedures/designs that could be used and explore the barriers to social housing.

METHODS

Thirty-nine sites, either running studies (Sponsors or Contract Research Organisations, CROs) and/or outsourcing work responded to the survey (51% from Europe; 41% from USA).

RESULTS

During safety pharmacology studies, 84, 67 and 100% of respondents socially house dogs, minipigs and non-human primates (NHPs) respectively on non-recording days. However, on recording days 20, 20 and 33% of respondents socially house the animals, respectively. The main barriers for social housing were limitations in the recording equipment used, study design and animal temperament/activity. During toxicology studies, 94, 100 and 100% of respondents socially house dogs, minipigs and NHPs respectively on non-recording days. However, on recording days 31, 25 and 50% of respondents socially house the animals, respectively. The main barriers for social housing were risk of damage to and limitations in the recording equipment used, food consumption recording and temperament/activity of the animals.

CONCLUSIONS

Although the majority of the industry does not yet socially house animals during telemetry recordings in safety pharmacology and toxicology studies, there is support to implement this refinement. Continued discussions, sharing of best practice and data from companies already socially housing, combined with technology improvements and investments in infrastructure are required to maintain the forward momentum of this refinement across the industry.

The shifting landscape of safety pharmacology in 2015

The relative importance of the discipline of safety pharmacology (which integrates physiology, pharmacologyand toxicology) has evolved since the incorporation of the Safety Pharmacology Society (SPS) as an entity on August 10, 2000. Safety pharmacology (SP), as a synthesis of these other fields of knowledge, is concerned with characterizing the safety profile (or potential undesirable pharmacodynamic effects) of new chemical entities (NCEs) and biologicals. Initially focused on the issue of drug-induced QT prolongation it has developed into an important discipline over the past 15years with expertise beyond its initial focus on torsades de pointes (TdP). It has become a repository for interrogation of models for drug safety studies and innovative non-clinical model development, validation and implementation. Thus, while safety pharmacology consists of the triumvirate obligatory cardiovascular, central nervous system (CNS) and respiratory system core battery studies it also involves assessing drug effects on numerous other physiological systems (e.g., ocular, auditory, renal, gastrointestinal, blood, immune) leveraging emerging new technologies in a wide range of non-clinical drug safety testing models. As with previous editorials that preface the themed issue on safety pharmacology methods published in the Journal of Pharmacological and Toxicological Methods (JPTM), we highlight here the content derived from the most recent (2014) SPS meeting held in Washington, DC. The dynamics of the discipline remain fervent and method development, extension and refinement are reflected in the content. This issue of the JPTM continues the tradition of providing a publication summary of articles (reviews, commentaries and methods) with impact on the discipline of safety pharmacology.