The use of recovery animals in nonclinical safety assessment studies with monoclonal antibodies: further 3Rs opportunities remain.

Assessment of reversibility from nonclinical toxicity findings in animals with potential adverse clinical impact is required during pharmaceutical development, but there is flexibility around how and when this is performed and if recovery animals are necessary. For monoclonal antibodies (mAbs) and in accordance with ICH S6(R1) if inclusion of recovery animals is warranted, this need only occur in one study. Data on study designs for first-in-human (FIH)-enabling and later-development toxicity studies were shared from a recent collaboration between the NC3Rs, EPAA, Netherlands Medicines Evaluation Board (MEB) and 14 pharmaceutical companies. This enabled a review of practices on recovery animal use during mAb development and identification of opportunities to reduce research animal use. Recovery animals were included in 68% of FIH-enabling and 69% of later-development studies, often in multiple studies in the same program. Recovery groups were commonly in control plus one test article-dosed group or in all dose groups (45% of studies, each design). Based on the shared data review and conclusions, limiting inclusion of recovery to a single nonclinical toxicology study and species, study design optimisation and use of existing knowledge instead of additional recovery groups provide opportunities to further reduce animal use within mAb development programs.

Species selection for nonclinical safety assessment of drug candidates: Examples of current industry practice.

In drug development, nonclinical safety assessment is pivotal for human risk assessment and support of clinical development. Selecting the relevant/appropriate animal species for toxicity testing increases the likelihood of detecting potential effects in humans, and although recent regulatory guidelines state the need to justify or dis-qualify animal species for toxicity testing, individual companies have developed decision-processes most appropriate for their molecules, experience and 3Rs policies. These generally revolve around similarity of metabolic profiles between toxicology species/humans and relevant pharmacological activity in at least one species for New Chemical Entities (NCEs), whilst for large molecules (biologics) the key aspect is similarity/presence of the intended human target epitope. To explore current industry practice, a questionnaire was developed to capture relevant information around process, documentation and tools/factors used for species selection. Collated results from 14 companies (Contract Research Organisations and pharmaceutical companies) are presented, along with some case-examples or over-riding principles from individual companies. As the process and justification of species selection is expected to be a topic for continued emphasis, this information could be adapted towards a harmonized approach or best practice for industry consideration.

Opportunities for use of one species for longer-term toxicology testing during drug development: A cross-industry evaluation.

An international expert working group representing 37 organisations (pharmaceutical/biotechnology companies, contract research organisations, academic institutions and regulatory bodies) collaborated in a data sharing exercise to evaluate the utility of two species within regulatory general toxicology studies. Anonymised data on 172 drug candidates (92 small molecules, 46 monoclonal antibodies, 15 recombinant proteins, 13 synthetic peptides and 6 antibody-drug conjugates) were submitted by 18 organisations. The use of one or two species across molecule types, the frequency for reduction to a single species within the package of general toxicology studies, and a comparison of target organ toxicities identified in each species in both short and longer-term studies were determined. Reduction to a single species for longer-term toxicity studies, as used for the development of biologicals (ICHS6(R1) guideline) was only applied for 8/133 drug candidates, but might have been possible for more, regardless of drug modality, as similar target organ toxicity profiles were identified in the short-term studies. However, definition and harmonisation around the criteria for similarity of toxicity profiles is needed to enable wider consideration of these principles. Analysis of a more robust dataset would be required to provide clear, evidence-based recommendations for expansion of these principles to small molecules or other modalities where two species toxicity testing is currently recommended.

Neurofunctional test batteries in safety pharmacology - Current and emerging considerations for the drug development process.

Regulatory guidelines recommend specialised safety pharmacology assessments in animals to characterise drug-induced effects on the central nervous system (CNS) prior to first-in-human trials, including the functional observational battery or Irwin test (here collectively termed neurofunctional assessments). These assessments effectively detect overtly neurotoxic drugs; however, the suitability of the in vivo assessments to readily detect more subtle drug effects on the nervous system has been questioned. A survey was formulated by an international expert working group convened by the (NC3Rs) to capture practice in CNS neurofunctional assessment tests and opinions on the perceived impact of in vivo test battery endpoints. Impact was defined as "the impact of measures alone/in combination on decision making in drug development or candidate selection when using the neurofunctional assessment". The results demonstrate that rodents are predominantly used for small molecule assessments, whereas non-rodents are frequently used to test biotherapeutics. Practice varied between respondents in terms of experimental design. Subsets of test battery endpoints were consistently considered highly impactful (e.g. convulsions, stereotypic behaviors); however, the perceived impact level of other endpoints varied depending whether drugs were designed for CNS targets. Many endpoints were considered to have no or minimal impact, whereas a subset of endpoints in CNS test batteries appears more impactful than others. A critical evaluation is required to assess whether the translational value of CNS in vivo safety pharmacology assessments could be increased by modifying or augmenting standard CNS test batteries. A revised approach to CNS safety assessment has the potential to reduce animal numbers without compromising patient safety.

The functional observational battery and modified Irwin test as global neurobehavioral assessments in the rat: Pharmacological validation data and a comparison of methods.

BACKGROUND: Evaluation of the effects of candidate drugs on the nervous system in preclinical safety pharmacology studies utilises a global neurobehavioral assessment, usually in the rat. This either takes the form of the functional observational battery (FOB) or modified Irwin Test, both of which evaluate effects across 4 functional domains: autonomic, neuromuscular, sensorimotor and behavioral. Although there is a great deal of overlap in the parameters they address, the two tests approach the assessments slightly differently. We undertook a broad pharmacological validation of both the FOB and the Irwin test, and compared the two outcomes. METHODS: Male rats (6 per treatment group) were used to assess each of 12 reference drugs alongside vehicle controls in separate FOB and Irwin studies. The drugs compared in the two study types were chlorpromazine, chlordiazepoxide, clonidine, baclofen, (+)-amphetamine, harmaline, 8-hydroxy-2-(di-n-propylamino)tetralin, buspirone, physostigmine, picrotoxin, yohimbine and atropine. There is a high degree of semantic equivalence in the parameters assessed in the autonomic domain between the two tests, with a lower degree of equivalence for neuromuscular and behavioral domains, whereas sensorimotor reflex testing in the FOB is far more extensive than in the Irwin test. RESULTS: Across the set of reference drugs, concordance between the two tests was generally good across the 4 functional domains at the 'domain' level (i.e., detecting 'an effect'), whereas there was generally a poor concordance at the individual parameter level. However, this was partially explained by variability between repeated studies on a single reference drug using the same test (FOB or Irwin). CONCLUSIONS: Both tests are 'fit-for-purpose' in detecting effects of candidate drugs on the nervous system. We would encourage the global safety pharmacology community to consider whether (a) the tests could be combined into one industry standard; (b) candidate drugs could be triaged according to CNS penetration, with the level of scrutiny in the CNS core battery assessment adjusted accordingly and (c) whether new home cage technology could be applied to semi-automate the preclinical neurobehavioral assessment.

The use of human tissue in safety assessment.

INTRODUCTION: The safety-related failure of drugs during clinical phases of development is a significant contributor to drug attrition, wasting resources and preventing treatments from reaching patients. A lack of concordance between results from animal models and adverse events in the clinic has been identified as one potential cause of attrition. In vitro models using human tissue or cells have the potential to replace some animal models and improve predictivity to humans. METHODS: To gauge the current use of human tissue models in safety pharmacology and the barriers to greater uptake, an electronic survey of the international safety assessment community was carried out and a Safety Pharmacology Society European Regional Meeting was organised entitled 'The Use of Human Tissue in Safety Assessment'. RESULTS: A greater range of human tissue models is in use in safety assessment now than four years ago, although data is still not routinely included in regulatory submissions. The barriers to increased uptake of the models have not changed over that time, with inadequate supply and characterisation of tissue being the most cited blocks. DISCUSSION: Supporting biobanking, the development of new human tissue modelling technology, and raising awareness in the scientific and regulatory communities are key ways in which the barriers to greater uptake of human tissue models can be overcome. The development of infrastructure and legislation in the UK to support the use of post-mortem or surgical discard tissue will allow scientists to locally source tissue for research.

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.

Safety pharmacology--a progressive approach.

Although deaths and life-threatening adverse drug reactions (ADRs) in Phase I clinical trials are extremely rare, less severe ADRs occur with an incidence of over 13%. Of the candidate drugs (CDs) that fail prior to marketing, it is generally acknowledged that about 1 in 5 do so because of ADRs in the clinic. Once new chemical entities (NCEs) are on the market, ADRs are estimated to be the fourth leading cause of death in the USA. These various statistics indicate that there is room for improvement in preclinical safety assessment, and a smarter approach to safety pharmacology (SP) can contribute to this. Rather than 'bundling' the SP studies together just prior to Phase I trials, a step-wise, streamlined approach can be adopted throughout the drug discovery process. In this way, the SP information can contribute to making informed judgements at each milestone throughout the preclinical drug discovery process: (i) to assist in series and compound selection; (ii) to assess potential risk of failure in the clinic due to ADRs; (iii) to predict potential ADRs that the clinical pharmacologists can focus on; (iv) to define a therapeutic window for acute dosing in humans. To achieve these objectives, the SP tests need to be carefully selected, adequately validated in-house, and be robust and reliable. To achieve (ii) above, outcome criteria have to be set which, for each test (in vitro and in vivo), take into account acceptable safety margins for the particular therapeutic target. Thus, highly sensitive and predictive SP tests positioned strategically and as early as possible should contribute to reducing attrition during clinical development and ultimately to marketing safer medicines more rapidly.