Replacing immunisation-dependent antibody reagent production: Challenges under the UK <i>Replacing</i> <i>Animals in</i> <i>Science</i> 2025 strategy

The UK’s 2025 Replacing Animals in Science strategy introduces a commitment to end polyclonal antibody reagent production by 2030. While this represents a significant milestone, focusing exclusively on polyclonal reagents raises scientific, ethical and implementation challenges, given that monoclonal and other recombinant antibody formats frequently remain dependent on animal immunisation. This study examines whether current UK licensing practice and reporting frameworks are positioned to deliver genuine replacement . A structured, Three Rs-aligned replacement framework is articulated, reflecting the principles set out in the UK Animals in Science Committee (ASC) 2022 review. This framework is applied to UK Non-Technical Summaries (NTS), to assess how antibody reagent production is justified at the project licence stage and the extent to which applications align with ASC expectations. In parallel, UK Home Office Annual Statistics of Scientific Procedures on Living Animals are analysed, to evaluate how antibody-related procedures are categorised, and to determine whether this national reporting enables progress toward the 2030 commitment to be monitored. The analysis identifies limited implementation of ASC replacement guidance in post-2022 licences, with few applications providing evidence-based interrogation of non-animal alternatives, documented use of validated in vitro discovery platforms, or robust justification for immunisation. The national statistics lack sufficient resolution to clearly capture immunisation-dependent antibody reagent production across commercial, basic and translational research contexts. In addition, inconsistent terminology complicates the interpretation of genuine replacement . Importantly, the findings indicate that, without complementary regulatory, reporting and infrastructural measures, the 2030 commitment risks being met through increased reliance on other immunisation-dependent antibody formats, geographical outsourcing, or reduced visibility of antibody production that is embedded within broader research categories, rather than through genuine replacement . Achieving the intended reduction in animal use will therefore require clearer terminology, improved reporting resolution, wider access to non-animal discovery infrastructure and the integration of a Three Rs-aligned decision framework into licensing expectations.