OECD Series on Adverse Outcome Pathways

An Adverse Outcome Pathway (AOP) describes a logical sequence of causally linked events at different levels of biological organisation, which follows exposure to a stressor and leads to an adverse health effect in humans or wildlife. AOPs are the central element of a toxicological knowledge framework, promoted by member countries through OECD, built to support chemical risk assessment based on mechanistic reasoning. These AOPs are available in the AOP-Wiki, an interactive and virtual encyclopaedia for AOP development. Following their development and review, the endorsed AOPs are published in the OECD Series on Adverse Outcome Pathways. As scientific knowledge progresses, the publication of an AOP in this series does not preclude regular updates or new contributions to a given AOP. While the AOP-Wiki is a dynamic tool, only impactful changes to the AOP will be reflected in subsequent updates of the published AOP.


Inhibitor binding to topoisomerase II leading to infant leukaemia

This Adverse Outcome Pathway (AOP) describes the linkages between the perturbation of the normal topoisomerase II enzyme function and infant leukaemia. Infant leukaemia is a rare haematological disease (1 in 106 newborns, accounting for 10% of all childhood acute lymphoblastic leukaemias) of developmental origin, manifesting soon after birth (< 1 year old). The present AOP describes how interference of stressors with DNA topoisomerase II enzyme can possibly result in DNA double-strand break and chromosomal rearrangement during intrauterine development and lead to infant leukaemia, manifesting soon after birth. The proposed AOP is supported by a number of evidences by means of using etoposide as a model compound to empirically support the linkage between the proposed molecular initiating event and the adverse outcome. This AOP also identifies several knowledge gaps, the main ones being the identification of the initiating cell and the investigation of TopoII poisons in a robust model; thus, the present AOP may be modified in future on the basis of new evidence. This AOP is referred to as AOP 202 in the Collaborative Adverse Outcome Pathway Wiki (AOP-Wiki).


Keywords: Infant leukaemia, Topoisomerase II, Genotoxicity
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error