Five decades of gene therapy innovation and regulation in the US and EU: a historical analysis.

The development of gene therapy is characterized by expectations of patient benefits, but challenges persist, including rapid technological change and, typically, small target populations. This has thus far resulted in relatively few gene therapies reaching the market and benefiting patients. Regulation plays a central role in shaping how these challenges are addressed and how gene therapies reach patients. This study investigated how gene therapy regulatory regimes have developed in the US and EU between 1973 and 2025, and how gene therapy regulation events contributing to regulatory regime building have shaped gene therapy innovation outcomes. We conducted a scoping review of scientific literature and expert interviews, which together characterized all authorized gene therapies in the US and EU. We constructed and validated timelines of gene therapy regulation events in these regimes. Interviewees attributed observed differences in the timelines to factors specific to gene therapy regulation and to the broader medicines regulatory system. Regulatory leadership in gene therapy has shifted repeatedly between the US and the EU, reflecting differences in how each jurisdiction responds to scientific and technological uncertainty, societal risks and needs, and commercial pressure.