The draft guidance outlines an approach to streamline testing of proposed products by reducing, refining, and replacing animal studies, including recommending against long-term chronic toxicology testing in non-rodent species (such as monkeys). It encourages the use of alternative approaches supported by a ‘weight-of-evidence’ (WoE) risk assessment. 

The guidance does not apply to multi-specific antibodies, oncology products, antibody constructs, or conjugated antibodies.

Industry stakeholders argue that the guidance is too narrow in scope. Organisations including Pharmaceutical Research and Manufacturers of America, Genentech, and the Biotechnology Innovation Organization have called for the FDA to expand the framework beyond single-target monoclonal antibodies to include multi-specific antibodies, antibody-drug conjugates, and other complex biologics, particularly in therapeutic areas such as oncology. They highlight that these products share key characteristics (such as predictable metabolism and target-driven toxicity) that justify similar streamlined testing approaches. 

A central theme in stakeholder feedback is the need for greater clarity around the WoE framework. Industry groups are seeking more detailed guidance on how to design, document, and incorporate these assessments into regulatory submissions, particularly within Investigational New Drug (IND) applications. There is also interest in understanding how prior knowledge (such as existing literature or data from similar drugs) can be used without requiring formal rights of reference.

Concerns were also raised about whether shorter toxicology studies would be sufficient to support later-stage clinical trials, with companies warning that uncertainty could undermine the intended efficiency gains. Meanwhile, advocacy groups such as the Humane World Action Fund argue the guidance does not go far enough, calling for stronger requirements, clearer benchmarks for reducing animal use, and greater transparency.

Overall, while the draft guidance represents progress, stakeholders agree that further refinement is needed to ensure both scientific rigour and meaningful reductions in animal testing.

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