Jazz Pharmaceuticals

Studies envision a not-so-distant future in which virtually all routine toxicity testing would be conducted in human cells or cell lines in vitro by evaluating cellular responses in a suite of toxicity pathway assays using high-throughput tests, that could be implemented with robotic assistance.

Healthcare organisations and the general public have both been increasingly frustrated with toxicity testing's failure to deliver timely, pertinent data to enable informed regulation of environmental agents in recent decades. The mainstay of current toxicity testing methods is the detection of negative health effects in experimental animals given high dosages of these substances. Such observations necessitate questionable extrapolations from high doses to environmental levels that are typically orders of magnitude lower than those utilised in animal research, and then from animals to humans, to conclude hazards to human populations. 

Conventional methods of testing for toxicity have existed for perhaps 30 to 60 years, and they were developed at a time when little was known about biology, particularly signalling pathways. Although toxicity testing procedures have gradually improved over time, advancements in cellular and molecular biology can be used to enhance them.

The toxicity tests' nature and the way the test results would be arranged to enable human health risk assessment are the revolutionary elements of the new toxicity testing paradigm. Modern biology encompasses a wide range of instruments and procedures that would be used to create these new toxicity testing protocols and analyse the results of these studies. Defining dose-response relationships for toxicity pathway perturbations that would be anticipated to result in adverse health outcomes if the perturbations were maintained in vivo at a sufficient level of intensity and for a period of sufficient length of time is the foundation of this vision for toxicity testing. Pathway testing would necessitate a set of tests that could pinpoint the several significant biological changes that exposure to chemicals might cause in humans.

High-throughput screens with robotic assistance would be used to carry out these experiments. These tests should ideally be carried out on human cells, cell lines, or tissues. Whole animal testing would be significantly less necessary if a wide range of in vitro tests of toxicity pathway responses were used to identify relevant biological perturbations using cellular and molecular systems based on human biology. These tests would also produce much more powerful, mechanistically based, predictive tools for assessing the risk to human health.

Improvements to Toxicity Testing Rather Than Alternatives to Animal Testing

This new vision focuses on substituting a suite of toxicity pathway assays for current toxicity testing methods that can be carried out quickly and effectively using modern robotics. Many in vitro test panels are being created to anticipate how laboratory animals will react to acute treatment, recurrent doses, or target-specific toxicity testing. Prioritization of substances for focused testing in animals is the current focus of the U.S. EPA ToxCast programme, which employs a range of high-throughput assays and computational methodologies. Nevertheless, for the long-term goal of revolutionising toxicity assessment, the methods and tools will be crucial.

The proposal substitutes high-dose animal testing with in vitro assessments of human biology disturbances caused by environmental chemicals and extrapolation of these assessments to in vivo human exposure circumstances. The suggested toxicity testing framework would only involve a small number of animals, and over time, significantly reduce the usage of animals for routine testing, despite not being intended as an "alternative to animal testing." In a best-case scenario, this new strategy would enable the generation of the large volumes of toxicity test data necessary to implement comprehensive regulatory risk assessment programmes, without increasing the use of laboratory animals, and would provide the data to support a human health risk assessment in weeks rather than years.

Coordination of in vitro and in vivo investigations will be necessary for the near future to better understand the connections between early perturbations and more integrated apical responses. Currently, substantial dosages of experimental animals are used for in vivo toxicity testing, and mechanistic study is done to aid in the interpretation of the results. It relies on mechanistically grounded, high-throughput experiments to pinpoint essential perturbations of toxicity pathways and to construct circumstances in which these perturbations are anticipated to have minimal effects on human health. Then, to contextualise these early responses, interpretive studies on the link between the simpler route responses seen in vitro and the more integrated, apical responses in vivo could be conducted.

The need to shift away from the existing "gold standard" for toxicological risk assessment, high dose animal experiments, and in favour of tests that look at human biology at relevant human exposure levels must also be emphasised. A multi-sector partnership between the government and industry, including the chemical, pharmaceutical, and consumer product industries, would broaden the base of funding and involve both regulators and the regulated communities in a common research effort of mutual interest and benefit. Although toxicity testing originally envisioned such a programme as existing within a publicly funded federal institute. Since environmental agents are tested for toxicity and their risks beyond national borders, the future course should be decided in conjunction with the global scientific and regulatory community.