Safety pharmacology in 2014: new focus on non-cardiac methods and models

Safety pharmacology methods and models in an evolving regulatory environment

This editorial prefaces the annual themed issue on safety pharmacology (SP) methods published in the Journal of Pharmacological and Toxicological Methods (JPTM). We highlight here the content derived from the recent 2016 Safety Pharmacology Society (SPS), Canadian Society of Pharmacology and Therapeutics (CSPT), and Japanese Safety Pharmacology Society (JSPS) joint meeting held in Vancouver, B.C., Canada. This issue of JPTM continues the tradition of providing a publication summary of articles primarily presented at the joint meeting with direct bearing on the discipline of SP. As the regulatory landscape is expected to evolve with revision announced for the existing guidance document on non-clinical proarrhythmia risk assessment (ICHS7B) there is also imminent inception of the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative. Thus, the field of SP is dynamically progressing with characterization and implementation of numerous alternative non-clinical safety models. Novel method development and refinement in all areas of the discipline are reflected in the content.

Recalibration of nonclinical safety pharmacology assessment to anticipate evolving regulatory expectations

Safety pharmacology (SP) has evolved in terms of architecture and content since the inception of the SP Society (SPS). SP was initially focused on the issue of drug-induced QT prolongation, but has now become a broad spectrum discipline with expanding expectations for evaluation of drug adverse effect liability in all organ systems, not merely the narrow consideration of torsades de pointes (TdP) liability testing. An important part of the evolution of SP has been the elaboration of architecture for interrogation of non-clinical models in terms of model development, model validation and model implementation. While SP has been defined by mandatory cardiovascular, central nervous system (CNS) and respiratory system studies ever since the core battery was elaborated, it also involves evaluation of drug effects on other physiological systems. The current state of SP evolution is the incorporation of emerging new technologies in a wide range of non-clinical drug safety testing models. This will refine the SP process, while potentially expanding the core battery. The continued refinement of automated technologies (e.g., automated patch clamp systems) is enhancing the scope for detection of adverse effect liability (i.e., for more than just IKr blockade), while introducing a potential for speed and accuracy in cardiovascular and CNS SP by providing rapid, high throughput ion channel screening methods for implementation in early drug development. A variety of CNS liability assays, which exploit isolated brain tissue, and in vitro electrophysiological techniques, have provided an additional level of complimentary preclinical safety screens aimed at establishing the seizurogenic potential and risk for memory dysfunction of new chemical entities (NCEs). As with previous editorials that preface the annual themed issue on SP methods published in the Journal of Pharmacological and Toxicological Methods (JPTM), we highlight here the content derived from the most recent (2015) SPS meeting held in Prague, Czech Republic. This issue of JPTM continues the tradition of providing a publication summary of articles primarily presented at the SPS meeting with direct bearing on the discipline of SP. Novel method development and refinement in all areas of the discipline are reflected in the content.

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.

Biophysics and Molecular Biology of Cardiac Ion Channels for the Safety Pharmacologist

Cardiac safety pharmacology is a continuously evolving discipline that uses the basic principles of pharmacology in a regulatory-driven process to generate data to inform risk/benefit assessment of a new chemical entity (NCE). The aim of cardiac safety pharmacology is to characterise the pharmacodynamic/pharmacokinetic (PK/PD) relationship of a drug's adverse effects on the heart using continuously evolving methodology. Unlike Toxicology, safety pharmacology includes within its remit a regulatory requirement to predict the risk of rare cardiotoxic (potentially lethal) events such as torsades de pointes (TdP), which is statistically associated with drug-induced changes in the QT interval of the ECG due to blockade of I Kr or K v11.1 current encoded by hERG. This gives safety pharmacology its unique character. The key issues for the safety pharmacology assessment of a drug on the heart are detection of an adverse effect liability, projection of the data into safety margin calculation and clinical safety monitoring. This chapter will briefly review the current cardiac safety pharmacology paradigm outlined in the ICH S7A and ICH S7B guidance documents and the non-clinical models and methods used in the evaluation of new chemical entities in order to define the integrated risk assessment for submission to regulatory authorities. An overview of how the present cardiac paradigm was developed will be discussed, explaining how it was based upon marketing authorisation withdrawal of many non-cardiovascular compounds due to unanticipated proarrhythmic effects. The role of related biomarkers (of cardiac repolarisation, e.g. prolongation of the QT interval of the ECG) will be considered. We will also provide an overview of the 'non-hERG-centric' concepts utilised in the evolving comprehensive in vitro proarrhythmia assay (CIPA) that details conduct of the proposed ion channel battery test, use of human stem cells and application of in silico models to early cardiac safety assessment. The summary of our current understanding of the triggers of TdP will include the interplay between action potential (AP) prolongation, early and delayed afterdepolarisation and substrates for re-entry arrhythmias.