Dutch toxicology company Toxys has announced the publication of OECD Test Guideline 446A for ToxTracker, its stem cell-based genotoxicity testing platform, marking formal recognition of the assay within international regulatory testing frameworks. The guideline, issued through the OECD Test Guidelines Programme, opens the door to wider use of ToxTracker in chemical, pharmaceutical and consumer product safety assessment.

What the guideline covers

ToxTracker is an in vitro assay designed to detect genotoxic hazards while also offering mechanistic insight into how a test substance causes damage. Rather than simply flagging a positive or negative result, the platform distinguishes between direct DNA reactivity and indirect genotoxicity arising from oxidative stress or protein damage, giving toxicologists a clearer picture of mode of action. Under OECD Test Guideline 446A, ToxTracker is positioned as a follow-up tool for equivocal findings generated by established in vitro genotoxicity assays, and as a means of generating mechanistic data to support the interpretation of positive genotoxicity results. This places it within the growing category of New Approach Methodologies (NAMs), which regulators and industry are increasingly looking to as alternatives to traditional animal-based testing. Giel Hendriks, chief executive officer of Toxys, described the milestone in strong terms. “Publication of the OECD Test Guideline for ToxTracker is a defining milestone for Toxys and for the broader adoption of NAMs in toxicology,” he said. He added that “the guideline enables organizations around the world to incorporate ToxTracker into regulatory testing strategies and represents an important step toward broader acceptance of next-generation safety assessment methods. We look forward to supporting our customers as they implement ToxTracker in their development and regulatory programs.”

Sector implications

The guideline is expected to support uptake of ToxTracker across the pharmaceutical, chemical, agrochemical, cosmetics and food sectors, all of which rely on genotoxicity data as part of regulatory submissions. By providing a harmonised framework for how the assay is applied and interpreted, OECD Test Guideline 446A gives laboratories and sponsors a standardised reference point when incorporating ToxTracker into study designs, potentially reducing reliance on repeat testing using conventional animal models. For clinical laboratory scientists and toxicologists working in genetic toxicology, the formal OECD status matters because it changes how ToxTracker data can be used in regulatory dossiers. Guideline-recognised methods carry more weight with regulatory authorities than proprietary or non-standardised assays, and this step may influence how laboratories structure their in vitro testing batteries when equivocal results emerge from first-line assays. Toxys, based in Oegstgeest, the Netherlands, specialises in genetic, developmental and investigative toxicology testing and works with research institutions and regulatory bodies internationally. The company states that its focus remains on providing mechanistic insight into test substances as part of its wider NAM portfolio. The full text of OECD Test Guideline 446A is available through the OECD Test Guidelines Programme.