This year, the UK introduced significant changes to the way in which clinical trials are conducted. The Medicines for Human Use (Clinical Trials) (Amendment) Regulations 2025 came into effect in all four nations of the UK on 28 April 2026. Developed jointly by the Medicines and Healthcare products Regulatory Agency (MHRA) and the Health Research Authority (HRA), these reforms revise the previous 2004 Regulations, and thus represent the most substantial change to clinical trial regulations in the UK in over 20 years.
The reformed Regulations apply to all Clinical Trials of Investigational Medicinal Products (CTIMPs) in the UK. They bring the UK closer to EU regulations, with a clear aim: to make the UK a more attractive jurisdiction for clinical research.
There is good reason for the ambition. The Association of the British Pharmaceutical Industry (ABPI) found that between 2017 and 2021, the UK fell from fourth to tenth place in global rankings for hosting Phase III trials (1). Similarly, between 2022/23 and 2024/25, the number of patients enrolled onto commercial clinical trials in the UK fell by as much as 25% (2).
The new reforms are intended to reverse that decline. They aim to accelerate clinical trial approvals via a streamlined and risk-proportionate review process. They were also amended with a view to increasing transparency.
Five key changes
- The combined review process becomes law
Every CTIMP application in the UK requires both a clinical trial authorisation (CTA) from the MHRA and a favourable ethical opinion from a Research Ethics Committee (REC) for trial approval. Previously, clinical trial sponsors were required to submit separate applications to each body to obtain trial approval. However, since January 2022, a ‘combined review’ service coordinating these two independent procedures has been available to applicants. With the new reforms, this combined review process is formally enshrined into law. The aim is to reduce unnecessary burden on trial sponsors and shorten the time to trial approval.
- A fast lane for notifiable trials
The Regulations introduce a notification scheme for CTIMP applications deemed relatively low-risk. These ‘notifiable trials’ are fast-tracked for automatic MHRA approval within 14 days of validation of the application. Approval of notifiable trial applications is therefore subject only to a favourable opinion by a REC; no assessment by the MHRA is required.
To qualify, an application must meet several safety criteria. These include, the absence of significant safety concerns associated with the investigational medicinal product (IMP) and the exclusion from the trial of participants who are under 18 years of age, breastfeeding or pregnant. This change marks the intention of the MHRA and HRA to move towards a more streamlined and risk-proportionate approach in review and approval of CTIMP applications in order to achieve accelerated approval timelines and reduced regulatory burden.
- Different processes for substantial modifications
Sponsors can modify a clinical trial after approval. Under the updated regulations, modifications are categorised as “minor modifications”, “modifications of an important detail”, or “substantial modifications” (3). Previously, every substantial modifications was necessarily subject to MHRA review. However, the updated regulations provide a route to automatic MHRA approval of a substantial trial modification provided there are no significant safety concerns arising from the modification. Substantial modifications are now split into two routes, categorised by risk:
- Route A substantial modifications are those deemed likely to have a substantial impact on trial participant safety, trial participant rights, or the robustness of trial data. Such modifications remain subject to MHRA review before approval.
- Route B substantial modifications, on the other hand, are those deemed low risk – wherein there are no substantial safety concerns associated with the proposed modification. Approval requires only a favourable REC opinion and is not subject to MHRA review.
- Updates to good clinical practice requirements
CTIMPs must now be conducted in accordance with the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) E6 (R3) Good Clinical Practice (GCP) principles, which were adopted in January 2025. Among the resulting changes is a focus on “proactively designing quality into clinical trials”. The principles also promote diversity: participant selection should be representative of the population in which the IMP is intended to be used, and sponsors must document their rationale for excluding any participants (4).
- Transparency becomes a legal obligation
Prior to the new reforms, there were no statutory obligations to register CTIMPs or report their results. Rather, expectations varied between research funders, publishers and industry associations, allowing clinical trials to go unregistered and unpublished. That lack of clinical trial transparency and data availability undermines patient safety and public trust in clinical research, and can hinder the progress of medical research.
This has now changed. Trial sponsors are obligated to:
- register the CTIMP in a public registry by the date on which the first participant is recruited or by 90 days after the date of trial approval, whichever is earlier;
- publish a summary of the trial results in the same public registry within 12 months of the trial concluding; and
- offer trial participants a lay-friendly summary of the trial results.
What the reforms mean for patent strategy
With the ultimate goal of positioning the UK as an attractive and internationally competitive destination for clinical research, these reforms were developed to make trial approval pathways faster, more streamlined and less burdensome without compromising patient safety. As patent attorneys, we also recognise that the reforms will have an impact on patent filing strategy.
Notably, the new rules introduce an obligation for all clinical trials to be registered and the results published within specified timeframes. Once a trial is registered, details of its design may be in the public domain. Sponsors should therefore decide, with counsel, how much detail to include in the registry entry, within what is legally required, so that commercially sensitive information is not disclosed any earlier or more fully than necessary. Depending on what the entry contains, that may include the patient population, dosing regimen, combination therapies, endpoints etc. Such information may be citable against later patent applications, and with faster trial approvals, earlier patent filings may become necessary. The 12-month post-trial results summary is a second, later disclosure. Unexpected efficacy findings, subgroup responses or biomarker data may support follow-on patent filings, but only if those filings are made before the summary is published. Trial modifications may alter the design in ways that create new patentable subject matter. Sponsors may want to flag these changes to IP counsel before they are approved.
All of this depends on good communication between clinical trial sponsors and their outside IP counsel, ideally from the earliest stages of trial design. The biotech team at Boult is highly experienced in navigating clinical trial disclosures alongside robust patent filing strategies. Get in touch with your usual Boult advisor with any questions.
References
- Association of the British Pharmaceutical Industry. UK clinical trials performance improves but remains in intensive care. [Online] 10 December 2024. [Cited: 25 August 2026.]
- Association of the British Pharmaceutical Industry. UK industry clinical trials: Translating actions into impact. [Online] 2 December 2025. [Cited: 25 August 2026.]
- Medicines and Healthcare products Regulatory Agency. Clinical trials for medicines: modifying a clinical trial approval. [Online] 19 August 2026. [Cited: 25 August 2026.]
- International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use. ICH HARMONISED GUIDELINE FOR GOOD CLINICAL PRACTICE E6(R3). [Online] 6 January 2025. [Cited: 25 August 2026.]
