The Medicines for Human Use (Clinical Trials) (Amendment) Regulations 2025 (the UK CTR Reforms) were signed into law in April 2025 and became applicable on 28 April 2026, following a 12-month implementation period. This legislation marks the most significant clinical trials reform in the United Kingdom in 20 years.
The UK CTR Reforms introduce a broad package of changes to the regulation of clinical trials of investigational medicinal products (CTIMPs) in the UK, including a combined review process for clinical trial applications, a notification-only scheme for certain low-risk trials, updated Good Clinical Practice (GCP) standards aligned with the ICH E6(R3) guideline, and new transparency requirements for trial registration and results disclosure.
Since Brexit, clinical trials regulation in the UK has remained based on the 2001 EU Clinical Trials Directive (EU CTD), while the EU has moved to the EU Clinical Trials Regulation (EU CTR). At the same time, the number of trials performed in the UK has declined over recent years, prompting the UK government to commission the O’Shaughnessy Review, which has identified changes to the UK regulatory landscape that would encourage more clinical trials. Some of these proposals are addressed in the UK CTR Reforms.
The UK CTR Reforms are intended to bring the UK’s regulatory framework into closer alignment with the current EU CTR, while preserving targeted, UK-specific features on timing, procedures, and registries in order to establish the UK as a leading jurisdiction for clinical trials.
Under the UK CTR Reforms, the Medicines and Healthcare products Regulatory Agency (MHRA) and research ethics committees (RECs) will conduct one combined review of clinical trial applications, replacing the prior practice of separate submissions and independent determinations. Applications will be made through the Integrated Research Application System (IRAS). This approach aligns with the EU CTR, which also has a single submission and assessment procedure.
Following a seven-day validation period, the MHRA and REC will review applications within a maximum of 30 calendar days. If the MHRA or REC requests further information, the sponsor has 60 days to respond, with the MHRA and REC then having a maximum of 10 calendar days after receiving such responses to issue a decision.
Sponsors must also recruit the first UK participant within two years of approval; otherwise, the approval will lapse, although extensions are available. This requirement helps keep benefit-risk assessments up to date and ensures that approved trials proceed without unnecessary delay.
The UK CTR Reforms introduce a notification scheme for certain low-intervention/lower-risk clinical trials (e.g., where the risk to participants is similar to standard medical care). Under this scheme, applications are automatically authorised within 14 days (without the need for full regulatory assessment), provided they meet specific criteria, including the absence of significant safety concerns and exclusion of higher-risk populations (such as children). Notably, REC approval is still required, similar to all other trials.
Under the current UK rules, substantial modifications to a clinical trial can only be approved or rejected by the MHRA. The UK CTR Reforms authorise the MHRA to request further information if anything is unclear during the review process, which may limit outright rejections.
The UK CTR Reforms provide sponsors with 60 days to respond to any request for information from the MHRA, again positioning the UK as a sponsor-friendly jurisdiction.
The UK CTR Reforms update GCP requirements to align with guidelines issued by the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH). In particular, the GCP provisions will align with ICH E6(R3), which took effect on 23 July 2025 and introduces several key changes, including:
The UK CTR Reforms introduce new transparency requirements. Clinical trials must be registered in a World Health Organization-recognised public registry before the recruitment of the first participant or within 90 days of the date of the clinical trial approval, whichever is sooner, unless an exemption or deferral has been granted. This reflects existing best practice adopted by the industry. Sponsors will also be required to publish a summary of trial results at the same public registry within 12 months of the trial’s completion, and to share a summary of the trial results with participants.
The UK CTR Reforms represent a significant modernisation of the UK’s clinical trials regulatory framework. While the reforms bring the UK into closer alignment with the EU CTR in several key areas, certain divergences remain that are designed to make the UK a more appealing jurisdiction for conducting clinical trials (e.g., shorter application review timelines and the notification scheme for low-risk trials).
To assist with implementation, the MHRA and the Health Research Authority (HRA) have both published guidance covering the key changes.