ASPIS Academy: A blueprint for building early-career researcher networks to advance NAM-based risk assessment.

Chemical risk assessment is moving away from traditional animal-based testing toward New Approach Methodologies (NAMs) that are more human-relevant, efficient, and aligned with the replacement, reduction, and refinement of animal use. This transition depends not only on new methods and technologies, but also on the researchers who will develop, apply, and promote them. Early-career researchers (ECRs) are central to this effort, yet they often work within fragmented professional networks and have limited opportunities for mentoring, visibility, and leadership. The ASPIS Academy (AA) was established within the ASPIS cluster, comprising the EU Horizon 2020-funded projects ONTOX, RISK-HUNT3R, and PrecisionTox, to support ECRs working on NAM-based chemical risk assessment. Built and coordinated by ECRs with support from senior advisors, AA evolved from an initial idea into an operational network offering training, mentoring, mirroring, twinning, communication, dissemination, and collaboration activities. Its development was shaped not only by strategic planning, but also by the practical realities of voluntary coordination and the changing needs of ECRs across large multidisciplinary consortia. This manuscript presents the establishment, growth, and legacy planning of AA as a case study for building ECR networks in collaborative research environments. We describe the decisions, challenges, lessons learned, and activities that helped the network become useful to its community and provide a practical blueprint for other consortia seeking to support the next generation of NAM scientists. The AA experience demonstrates that empowering ECRs to lead can strengthen scientific communities and accelerate the uptake of NAMs.