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Evaluating the Need for the Use of Two Species in Toxicity Testing

Overview

Regulatory agencies typically require toxicity testing in both a rodent and a non-rodent species before new drugs can proceed to human trials. Given rapid advancements in human-relevant science, what new approaches might augment or substitute the traditional two-species model?

This hybrid workshop, hosted by faculty and members of the Toxicology Policy Program at Johns Hopkins Bloomberg School of Public Health and Cruelty Free International, will critically examine the scientific, ethical and regulatory case for moving toward a single-species approach – especially for longer-term toxicity studies (e.g. 3 to 6+ months). We will build on recent advances, including the ICH S1 guideline revision, which introduced a new approach to reducing animal testing for carcinogenicity, and emerging modern, human-relevant non-animal methods (NAMs), to explore how regulatory flexibility could drive meaningful change.

Who Should Attend?

  • Toxicologists, drug development experts, regulatory scientists, and professionals in animal-free science

  • Researchers and developers working on NAMs e.g., microphysiological systems (MPS), in silico models and other human-relevant alternatives to systemic toxicity testing

  • Stakeholders interested in evidence-based reform of international regulatory guidelines

Workshop Structure:

The workshop will be held in two parts:

Part One: Reassessing the Two-Species Requirement

  • What does the current evidence say about the scientific use of the second species test?

  • Under what conditions could the second species requirement be waived?

  • What updates are needed to the ICH M3 guideline?

Part Two: The Role of Non-Animal Methods (NAMs)

  • What cutting-edge NAMs could replace or supplement animal testing for systemic toxicity?

  • How can a weight-of-evidence (WoE) framework be constructed using NAM data to support regulatory decisions?

What You’ll Do:

As a participant, you will:

  • Join hybrid sessions either in-person at Johns Hopkins University or online

  • Engage in expert presentations, discussions and breakout groups

  • Help shape a formal proposal to ICH for revising outdated testing guidelines

  • Contribute to a peer-reviewed report summarizing the workshop outcomes

Date and Location

When:

Session 1: October 24th, 2025 (Bloomberg Center DC?)

Session 2: November 7th, 2025 (BPSH – Feinstone Hall?)

Where: Hybrid format – in-person at Johns Hopkins Bloomberg School of Public Health, Baltimore, MD or online

Sign Up Now

This event is free to attend.

Register your interest and receive workshop updates by clicking [HERE TO SIGN UP].

For more information, please contact Laura Alvarez at laura.alvarez@crueltyfreeinternational.org.

Background Resources:

To prepare for the workshop, you may find these documents helpful: [ADD LINKS TO EACH]

Next
January 2

Event Two