Challenge 10

PREDART

Launched Phase 1 awarded Phase 2 awarded Completed

The aim of this Challenge is to develop and characterise non-mammalian assays that can provide an indication of developmental and reproductive toxicity potential to mammals, including man, in order to reduce and refine in vivo mammalian testing.

Publication

Racz PI, Wildwater M, Rooseboom, et al. (2017). Application of Caenorhabditis elegans (nematode) and Danio rerio embryo (zebrafish) as model systems to screen for developmental and reproductive toxicity of Piperazine compounds. Toxicology in Vitro 44: 11-16. doi.org/10.1016/j.tiv.2017.06.002.

Product launched

The Vivaltes service pipeline offers non-mammalian Caenorhabditis elegans (C. elegans) testing for Developmental and Reproductive Toxicology (DART).

Challenge completed

The PREDART Challenge led by Professor Raymond Pieters, Institute for Risk Assessment Sciences/ Toxicology, has been successfully completed. In the process, the team formed a company called Vivaltes that offers a service pipeline for toxicological assessments using non-mammalian species.

Conference presentation

51st Congress of the European Societies of Toxicology (Porto, Portugal)

Conference presentation

SETAC Europe 25th Annual Meeting (Barcelona, Spain)

Conference presentation

Society of Toxicology’s 53rd Annual Meeting (Arizona, USA)

Phase 2 awarded

A team led by Professor Raymond Pieters, Institute for Risk Assessment Sciences/Toxicology, has been awarded £750,000 to deliver the project: An integrative Dictyostelium, C. elegans and zebrafish approach to assess DART.

Conference presentation

19th International C. elegans Meeting (Los Angeles, USA)

Phase 1 awarded

Three Phase 1 Awards were made to project teams led by:

  • Professor R Wayne Glasse-Davies, Brainwave‐Discovery Ltd, £96,600.
  • Dr Nils Klüver, Helmholtz Centre for Environmental Research GmbH ‐ UFZ, £99,957.
  • Professor Raymond Pieters, Institute for Risk Assessment Sciences/ Toxicology, £100,000.

Challenge launched

Sponsored by Shell and Syngenta, the PREDART Challenge aims to develop and characterise non-mammalian assays that can provide an indication of developmental and reproductive toxicity potential to mammals, including man, in order to reduce and refine in vivo mammalian testing.

Background

Developmental and reproductive toxicity studies in rats and rabbits form the main basis for regulatory assessment of the potential effects of chemicals on the developing foetus. These studies use large numbers of animals, are expensive and time consuming. In addition, the relevance to humans of effects seen in these studies is not always clear and significant species differences exist. In addition, there remains a dearth of information about the fundamental pathways of embryogenesis and the effects of toxicity on them.

If a compound is found to be toxic to reproduction and/or development, this has significant consequences for potential use of the product, including restriction from occupational and/or consumer use or prohibition of authorisation for any use under regulatory schemes, including REACH and the EU’s plant protection products regulation. It is therefore important to obtain an indicator of developmental toxicity early in the product development pipeline.

In the past the use of alternative models in lower species or in vitro systems has been hampered by the drive for a 1:1 predictive screen for mammalian outcomes. However, in the absence of an understanding of the complex underlying developmental pathways and species differences this has proved to be unachievable.

In recent years numerous alternative developmental biology model systems have been explored, ranging from whole organism systems including zebrafish, Caenorhabditis elegans and slime moulds, to cell based systems using mouse or human embryonic stem (ES) cells. Groups working with these systems are embracing and exploiting the explosion in molecular biology and genetics to better understand the underlying pathways driving normal embryogenesis and the effects of perturbations to these pathways.

The key to unlocking the potential of these alternative test systems is to understand the conservation of key pathways across different species, including mammals, and to use these non-mammalian (surrogate) systems to inform mammalian toxicity potential. The issue of exposure concentrations in the test systems versus those in rats/rabbits and humans will also need to be assessed. There has been progress in this direction in recent years, but there is now a need for a focused effort towards practical, commercial solutions, which will include an integration of the available systems.

3Rs benefits

A standard two-generation reproductive and developmental toxicity study typically uses around 2,500 test animals. An early indication of developmental toxicity potential during compound development (such as relevant pathway perturbations) would be of benefit as a screening or ranking tool, helping to inform compound selection and direct testing strategies. The information can also be used to predict structure activity relationships (SAR) and steer chemistry design away from these key alerts.

This could impact on animal use in a number of ways including.

  • Reducing the number of regulatory toxicity studies carried out in animals (e.g. developmental and reproductive toxicity, teratogenicity, carcinogenicity) on compounds with potential for developmental toxicity that would not therefore be progressed into product development.
  • Supporting weight of evidence and/or read across arguments for registration, consequently reducing and replacing the use of animals for developmental toxicity testing. In the longer term as our understanding of underlying pathway perturbations improves and confidence is gained in these models, the opportunities to replace the use of rodents and rabbits will increase.

Phase 1 winners

Project teams led by:

  • Professor R Wayne Glasse-Davies, Brainwave‐Discovery Ltd, £96,600.
  • Dr Nils Klüver, Helmholtz Centre for Environmental Research GmbH ‐ UFZ, £99,957.
  • Professor Raymond Pieters, Institute for Risk Assessment Sciences/ Toxicology, £100,000.

Phase 2 winner

Project team led by:

Full Challenge information

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Through the PREDART Challenge, the team developed a test battery of assays combining three alternative non-mammalian test systems (the zebrafish Danio rerio, the nematode C.elegans and the social amoeba Dictyostelium discoideum) to pre-screen compounds for developmental and reproductive toxicity (DART) and identify mechanisms of action, reducing the number of regulatory animal studies carried out.

The advantages of the test systems include rapid high throughput screening, short turnover time enabling the entire developmental and reproductive cycle to be examined and easy identification of adverse outcomes pathways and molecular imitating events. The assays have been validated using 42 well characterised DART positive and negative compounds. D. Discoideum, C.elegans and D.rerio detected DART compounds with assay sensitivity values of 87%, 87% and 74%, respectively (Table 1.). Combining all three test systems increases the sensitivity to 92%, highlighting the value of the combinatorial approach.

The team has formed a company, Vivaltes B.V. which offers the alternative non-mammalian test system assays as a screening service. If you are interested in using alternative non-mammalian models as a screen or would like further information, please contact Dr Marjolein Wildwater.

Table 1. Sensitivity of the three alternative non-mammalian test systems in detecting DART.

Vivaltes

Product description:

The Vivaltes service pipeline offers non-mammalian Caenorhabditis elegans (C. elegans) testing for Developmental and Reproductive Toxicology (DART).

While cell based in vitro tests are an attractive alternative for animal studies, they do not always recapitulate the whole organism effects of chemicals. C. elegans is a multicellular organism, with neuronal, motor, digestive, and reproductive systems, endocrine signalling, and sensory/behavioural responses to stimuli.

Vivaltes’ strategy allows medium throughput pre-screening of compounds to select the most promising compounds to enter product development pipelines, reducing the number of in vivo studies performed. In addition, use of the test system provides biological insight into how compounds cause their effects, improving future compound/drug design.

 

Features

Humans and C. elegans are highly conserved

The organism has been studied for over 55 years, providing a large body of knowledge to inform detected outcomes. Humans and C. elegans have a common ancestor meaning many key biological pathways are conserved.

Ease of handling and rapid lifecycle


The ease of handling permits multiple concentrations and exposure times to be assessed simultaneously. The rapid lifecycle allows for low-dose lifespan and multigeneration testing in weeks rather than years.

Multiple endpoints



Multiple types of toxicity ranking screens have demonstrated good correlation of endpoints in C. elegans to rat LD50s.

You can find out more about this product on the Vivaltes website.