ICH Guide Seeks to Reduce Rat Studies

The International Council for Harmonization is challenging the usefulness of two-year rat studies in a just-released Addendum to the Guideline on Testing for Carcinogenicity of Pharmaceuticals S1B(R1). The document expands the testing scheme for assessing human carcinogenic risk of small molecule pharmaceuticals by introducing an additional approach that is not described in the original S1B Guideline — a weight-of-evidence approach to determine whether or not a two-year rat study adds value in completing a human carcinogenicity risk assessment. “Application of this integrative approach would reduce the use of animals in accordance with the Rs (reduce/refine/replace) principles, and shift resources to focus onto generating more scientific mechanism-based carcinogenicity assessments, while promoting safe and ethical development of new small molecule pharmaceuticals,” the guide says.