The in vitro ɣH2AX/pH3 method has recently emerged as a potential regulatory test that could complement the current battery of in vitro tests for evaluating the in vitro genotoxic potential of chemicals. It combines in a single assay two specific phosphorylated histone biomarkers, ɣH2AX and pH3. γH2AX is an early marker of DNA damage, while pH3 is indicative of mitotic disruption and aneugenicity. Together, these biomarkers aim to discriminate between genotoxicants and non-genotoxicants and to provide insight into the mode of action of chemicals identified as genotoxicants.
First commenting round on a Detailed Review Paper on in vitro mammalian cell genotoxicity methods based on the phosphorylated histone biomarkers ɣH2AX and pH3
- Submission period
- 15 May - 26 June 2026
Background public consultation
Project description
The project to develop a Detailed Review Paper (DRP) on in vitro mammalian cell genotoxicity assays based on the ɣH2AX and pH3 histone biomarkers, was included in the Test Guideline Programme workplan in April 2023, on a joint proposal from France and Germany. The document describes various methods associated with the detection of the two biomarkers and includes an extensive retrospective performance analysis of the data collected with these methods.
How to contribute
The draft new DRP on in vitro mammalian cell genotoxicity assays based on the ɣH2AX and pH3 histone biomarkers is currently under a commenting round by the Working Party of the National Coordinators of the Test Guidelines Programme and open for comments from the public at the same time. Interested parties are invited to submit comments to their National Coordinators at least a week before 26 June 2026.
