This post was written by Erin Janssen.

The FDA recently published a guidance document entitled “S2(R1) Genotoxicity Testing and Data Interpretation for Pharmaceuticals Intended for Human Use.” This guidance combines and replaces two ICH guidances, S2A Specific Aspects for Regulatory Genotoxicity Tests for Pharmaceuticals (ICH S2A guidance) and S2B Genotoxicity: A Standard Battery for Genotoxicity Testing of Pharmaceuticals (ICH S2B guidance). The purpose of the revision is to provide guidance on optimizing the standard genetic toxicology battery for prediction of potential human risks, and on interpreting results, with the goal of improving risk characterization for carcinogenic effects that have their basis in changes in the genetic material. The revised guidance describes internationally agreed-upon standards for follow-up testing and interpretation of positive results in vitro and in vivo in the standard genetic toxicology battery, including assessment of nonrelevant findings. This guidance is intended to apply only to products being developed as human pharmaceuticals.