In-vitro genotoxicity proves viable alternative to animal testing
potentially viable alternative to animal testing, reducing the need
for their use during drug development.
As well as providing a valuable new tool to confirm positive data from existing tests, the new human cell-based genotoxicity test aims to reduce the number of compounds going on to animal testing. The use of this new test will not only reduce the number of animals used in genotoxicity testing but also reduce the considerable costs of conducting animal tests. The research award of £133,024 (€196,714) has been granted to Gentronix by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs). The test specifically focuses on the development of a novel genotoxicity assay in a human liver cell line, designed to reduce the use of live animals in drug development. Most scientists and governments agree that animal testing should cause as little suffering to animals as possible, and that animal tests should only be performed where necessary. Reduction refers to methods that enable researchers to obtain comparable levels of information from fewer animals, or to obtain more information from the same number of animals. Replacement refers to the preferred use of non-animal methods over animal methods whenever it is possible to achieve the same scientific aim. Refinement refers to methods that alleviate or minimise potential pain, suffering or distress, and enhance animal welfare for the animals still used. The existing mammalian cell in vitro tests are highly sensitive so most carcinogens are identified, but many safe compounds are also falsely identified as potential carcinogens. Because this can lead to needless loss of useful new drugs, live animal tests are still conducted when there is only one in vitro positive result. By using a new high specificity human cell-based genotoxicity test, the aim will be to reduce the number of compounds tested on animals. Preliminary validation studies with a new human cell genotoxicity test have demonstrated an ability to detect all direct acting mechanistic classes of genotoxic chemicals, as well as aneugens and compounds disrupting DNA replication and repair. Results recently reported by Gentronix and GSK in Mutation Research show the new assay to have sensitivity comparable to that of existing mammalian in vitro genotoxic assays, but uniquely combined with very high levels of specificity. However, some compounds (promutagens) are only carcinogenic after passing through the liver, and regulations require a separate test to be performed using liver tissue extracts.
