Towards a more proportionate EU framework for low-intervention clinical trials: Lessons from the UK and Switzerland

Post-marketing treatment-optimisation trials evaluate established therapies to determine their optimal dosage, duration, sequencing, scheduling, and use in combination strategies. Although these studies may qualify as low-intervention clinical trials and generally entail lower additional risks than pre-authorisation drug-development trials, the current EU framework for these trials entails disproportionate regulatory requirements that may impede their conduct, particularly in multinational academic research that aims to improve patient-relevant outcomes, including quality of life, rather than to support the development or registration of new medicinal products.

This article undertakes a comparative legal and policy analysis of the low-risk clinical trial frameworks applicable in the European Union (EU), United Kingdom (UK), and Switzerland (CH). It identifies the principal elements within the legal provisions of each jurisdiction that determine whether a clinical trial may be categorised as low-risk and examines the regulatory implications that follow from such classification. More practically, the EU and CH low-risk framework divergencies are highlighted in the EORTC 2238 'DE-ESCALATE' prostate cancer trial case study. Texts were analysed as in force or proposed in September 2026.

In the EU, low-intervention status depends on product authorisation, evidentiary support, and minimal added procedural risk, while leaving the role of established clinical practice less explicitly defined than in the UK and CH frameworks. The UK also provides a notification-based route, and CH exempts qualifying Category A trials from Swissmedic authorisation. DE-ESCALATE illustrates the resulting differences in timelines, costs, and review burdens.

EU reform should clarify the low-intervention clinical trial definition by specifying acceptable evidence and recognising context-based established clinical practice. Classification should also produce proportionate regulatory consequences, including an accelerated notification pathway and, where appropriate, review centred on Ethics Committee approval.