Overview of Revision of Guidelines for Carcinogenicity Testing of Pharmaceuticals

Abstract

ICH S1 (R1) Expert Working Group (EWG) has been investigating whether the value of the conduct of a two-year rat carcinogenicity study can be judged by an integrated “weight of evidence” approach based on various factors. From the results of the prospective evaluation conducted to verify this possibility, it was possible to judge whether or not to add value to the assessment of carcinogenicity risk in humans for some groups of pharmaceutical products without conducting a 2-year rat carcinogenicity study. Therefore, it was judged appropriate to expand the new carcinogenicity assessment framework based on the integrated “weight of evidence” WoE approach, and ICH S1B (R1) guideline was finalized in August 2022 and implemented in March 2023 in Japan. This review describes an overview of the background to the revision of the guideline and the prospective evaluation on which the revision was based.