> ## Content Index
> Fetch the complete content index at: https://www.fdaweb.com/llms.txt
> Use this file to discover other available public pages before exploring further.

# ICH Carcinogenicity Testing Supplement Out
- URL: https://www.fdaweb.com/ich-carcinogenicity-testing-supplement-out/
- Published: 2021-10-06T12:00:00.000Z
- Updated: 2026-09-14T17:18:01.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5150309

FDA has published a draft S1B addendum to the International Council for Harmonization (ICH) S1 guidances and documents on the need for carcinogenicity studies for pharmaceuticals. The ICH says the addendum expands the testing scheme for assessing the human carcinogenic risk of small molecule pharmaceuticals by introducing an additional approach that was not described in the original S1B testing guideline.

“This is an integrative approach that provides specific weight-of-evidence criteria that inform whether or not a two-year rat study adds value in completing a human carcinogenicity risk assessment,” the [document](https://www.fda.gov/regulatory-information/search-fda-guidance-documents/s1br1-addendum-s1b-testing-carcinogenicity-pharmaceuticals?ref=fdaweb.com) says.