Clinical trials generate data directly relevant to patentable inventions in the pharmaceutical field. Innovator pharmaceutical companies must balance the legitimate public interest in clinical trial transparency with the need to protect commercially confidential information. In the European Union, that balance is addressed through the Clinical Trials Information System (CTIS), established under the Clinical Trial Regulation (EU) No 536/2014,[1] which entered into force on 31 January 2022, and revised transparency rules adopted in June 2024 (discussed in our previous article here). The United Kingdom has now enacted its own modernised framework through the Medicines for Human Use (Clinical Trials) (Amendment) Regulations 2025[2] (the “2025 Amendment”), which introduces mandatory public registration and results publication requirements for UK clinical trials.
This article examines the new UK transparency requirements, compares them with the EU CTIS framework, and considers the strategic implications for patent filings, such as at the European Patent Office (EPO).
The UK Regulatory Framework: From the 2004 Regulations to the 2025 Amendment
The Original Framework: S.I. 2004/1031
The Medicines for Human Use (Clinical Trials) Regulations 2004[3] came into force on 1 May 2004, implementing EU Directive 2001/20/EC into UK law. Under that framework, a sponsor had to submit separate applications: one to the Medicines and Healthcare products Regulatory Agency (MHRA) for clinical trial authorisation, and one to a research ethics committee for an ethical opinion.
Notably, the 2004 Regulations did not require sponsors to register trials in a public registry or publish results. In accordance with Regulation 27B introduced in the 2019 Amendment to the Regulation, sponsors were required to notify the licensing authority of trial completion, and the authority had discretion to publish certain information.[4]
The 2025 Amendment, A Post-Brexit Modernisation: S.I. 2025/538
The 2025 Amendment was made on 28 April 2025 under powers conferred by the Medicines and Medical Devices Act 2021[5] and came into force on 28 April 2026. It extends to England, Wales, Scotland, and Northern Ireland.
Key changes include a combined approval procedure under new Regulation 16 (alongside new Schedule 3 Part A1),[6] which replaces the dual application system with a single “request for approval” covering both regulatory authorisation and ethics committee opinion, leading to a co-ordinated review and a single UK decision.
Of greatest significance for patent strategy are the new transparency requirements introduced by Regulation 25, discussed below.
New Transparency and Publication Requirements
Registration Obligation
New Regulation 25 imposes a positive obligation on sponsors to register clinical trials in a public registry.[7] The registration must take place by the earlier of:
(a) the date the first individual is recruited as a participant in the trial; or
(b) 90 days after the date of approval of the clinical trial.
A “public registry” is defined as a primary or partner registry of, or data provider to, the WHO International Clinical Trials Registry Platform (ICTRP), provided it facilitates public access to information about clinical trials conducted in the United Kingdom.[8]
The Health Research Authority (HRA) has published the data displayed in an ISRCTN registration record: What data will be shared with ISRCTN Registry? - Health Research Authority
Results Publication
Within 12 months of the conclusion of the trial, the sponsor must:
(a) publish a summary of results in the same public registry in which the trial was registered;[9] and
(b) offer to all relevant persons (including participants, their legal representatives, carers, or next of kin) a summary of results written in a manner understandable to laypersons.[10]
Enforcement
Failure to register or publish a summary of results, without any deferral or waiver, is an offence and, if not corrected, may result in MHRA enforcement action.[11]
Deferrals and Waivers
Recognising that immediate public disclosure may prejudice commercially confidential information, the 2025 Amendment provides a system of deferrals and waivers.[12] The sponsor may apply, when requesting approval or before the relevant deadline, for a deferral or waiver of the requirement to register a clinical trial in a public registry and/or publish results within 12 month of conclusion of the trial.
The licensing authority may defer registration or results publication for up to 30 months from the day after conclusion of the trial, for example to protect commercially confidential information. Once a deferral is agreed, the sponsor should publish a minimal record on a publicly accessible registry.[13] A sponsor may also apply for further deferrals, each of up to 30 months.[14] In exceptional circumstances, such as national defence and security, the authority may waive the requirement entirely.
For Phase I trials, the authority may provide an automatic deferral of: (a) the requirement to register the clinical trial in a public registry for up to 30 months after conclusion of the trial, provided the sponsor registers “required minimum information” (i.e., particulars identifying the trial and details of the sponsor and investigator)13 before the registration deadline; and (b) the results publication requirement for up to 30 months after conclusion of the trial.[15]
The maximum combined deferral period under any combination of these provisions is 10 years from the day after the conclusion of the trial.[16]
Transitional Provisions
The transitional provisions in Schedule 14 of the 2025 Amendment[17] provide that Regulation 25 applies to “old rules clinical trials” (i.e., trials for which a request for authorisation or an application for ethics committee opinion has been received before 28 April 2026), with the following exceptions:
(a) trials that concluded before 28 April 2026 are entirely exempt;
(b) for old rules trials that have been approved and have an end of trial date on or after 28 April 2026, the registration deadline is the earlier of first trial participant recruitment and 90 days after 28 April 2026; and
(c) the obligation to offer a layperson summary (Regulation 25(2)(b)) does not apply to old rules trials.
These transitional provisions are of practical significance for sponsors with existing trial portfolios, who must ensure compliance for ongoing trials.
Comparison with the EU Clinical Trials Information System
In an earlier article, accessible here, we reviewed the EU transparency rules for clinical trial information submitted via the EU Clinical Trials Information System (CTIS). These rules aim to balance transparency with the protection of personal data and commercially confidential information (CCI). Importantly, CTIS allows users to submit both 'for publication' and 'not for publication' versions of documents, enabling personal data and CCI to be redacted from publicly available versions.
By contrast, the UK system mandates public registry registration and results publication, but allows sponsors to apply for deferrals or waivers.
Strategic Approaches to Patent Filings at the EPO
Any public disclosure concerning a drug and/or its therapeutic use before the relevant priority or filing date may constitute prior art for a patent application relating to that drug or therapy and may therefore be detrimental to the grant of a patent. Consequently, information published in a clinical trial public registry under Regulation 25 or disclosed by the MHRA under Regulation 27B may be relevant prior art for European patent applications.
The new UK requirements create several trigger points at which information may enter the public domain. These are summarised in the table below with the available deferral periods.
| Timepoint | When | Deferral, e.g. to protect commercially confidential information |
| Registration in a public registry (Reg 25(1)) | By first trial participant recruitment or 90 days after approval (whichever is earlier). | Deferral of up to 30 months after conclusion of the trial (Reg 25(5)). Phase I automatic deferral up to 30 months after conclusion of the trial (Reg 25(10)). Further deferrals are available where justified; the maximum combined period is 10 years (Reg 25(11)). Deferrals after the initial 30-month period will normally apply only to results publication and participants’ summaries. |
| Results publication in the public registry (Reg 25(2)) | Within 12 months of conclusion of the trial. | |
| Layperson summary (Reg 25(2)) | Within 12 months of conclusion of the trial. | |
| Authority disclosure (Reg 27B) | At the Authority’s discretion, subject to prior publication of a disclosure list. | None. |
Determining the optimum time to file a patent application requires balancing the need to file before clinical trial documents are published, as those documents could become prior art[18] relevant for the assessment of novelty and inventive step, against the need to include sufficient data to meet disclosure requirements. For a medical use claim to be sufficiently disclosed, the application and/or the common general knowledge must provide some information making it credible that the therapeutic agent is suitable for the claimed therapeutic application.[19] Applicants must therefore weight the risk of additional publications being added to the state of the art when filing late and the risk of insufficiency of their own invention when filing early.
The relevance of clinical trial-related disclosures will depend on the information already in the public domain regarding the subject matter of interest, such as the drug and/or therapy being investigated. A detailed review of the case law in this field, published in March and April 2025, can be found here and here.
The most effective strategy remains filing patent applications before any relevant information enters a public registry. Given that registration must occur by the earlier of first participant recruitment or 90 days after approval, sponsors should ensure that patentable inventions identified from pre-clinical and/or early clinical data are captured in patent applications filed before the trial registration deadline. Sponsors may use the UK deferral provisions to allow more time for filing a patent application, in particular where data from the trial would be needed to meet the sufficiency and/or inventive step requirements.
For Phase I trials in healthy volunteers, the automatic deferral of up to 30 months after conclusion of a trial may allow sponsors to finalise their patent filing strategies before disclosure obligations take effect. Sponsors must nevertheless register “required minimum information” (particulars identifying the trial and details of the sponsor and investigator). Practitioners should therefore assess whether that minimum information, taken alone or in combination with other publicly available data, could prejudice patentability.
Conclusion
The 2025 Amendment represents a significant step in the UK’s post-Brexit development of an independent clinical trials regulatory framework, in particular with the introduction of mandatory registration and results publication requirements under Regulation 25.
For patent practitioners, these changes introduce new considerations that should be integrated into patent filing strategies. Importantly, the deferral mechanisms for protecting commercially confidential information offer significant flexibility.
The key to navigating this new landscape is early engagement between patent, regulatory and clinical teams; proactive use of deferral mechanisms; careful management of the information included in “required minimum information”; and coordination with timelines in other jurisdictions such as EU CTIS timelines for multinational trials.
[1]Regulation (EU) No 536/2014 of the European Parliament and of the Council of 16 April 2014 on clinical trials on medicinal products for human use, and repealing Directive 2001/20.EC.
[2]The Medicines for Human Use (Clinical Trials) (Amendment) Regulations 2025, S.I. 2025/538.
[3]The Medicines for Human Use (Clinical Trials) Regulations 2004, S.I. 2004/1031.
[4]The 2019 Amendment to the Regulation inserts new Regulation 27B, “Publication of information”, which provides that the licensing authority may make information relating to the trial accessible to the public. Before doing so, the authority must, after consulting such persons as it considers appropriate, publish a list of the information that may be made accessible to the public.
[5]Medicines and Medical Devices Act 2021, c. 3.
[6]S.I. 2025/538, Regulation 16 (combined approval procedure).
[7]S.I. 2025/538, Regulation 25(1).
[8]S.I. 2025/538, Regulation 25(12): definition of ‘public registry’ as a primary or partner registry of, or data provider to, the WHO ICTRP. Both ISRCTN and ClinicalTrials.gov are registries that meet the definition of a public registry under the regulations. Registration with the EU Clinical Trials Information System (CTIS) or EudraCT does not satisfy the trial registration requirement in the 2025 regulations.
[9]S.I. 2025/538, Regulation 25(2)(a).
[10]S.I. 2025/538, Regulations 25(2)(b) and 25(12). The summary results should describe the trial's results as a whole, not the participant’s individual results.
[11]S.I. 2025/538, Schedule 14.
[12]S.I. 2025/538, Regulation 25(3)–(5) and (8)-(9).
[13] According to the HRA (Deferrals - Health Research Authority, accessed on 7 July 2026), the “required minimum information” includes: registry number, IRAS ID, chief investigator name and site address, sponsor name and address, REC decision and date of decision, nature of clinical trial (for example, bioequivalence in 24 healthy volunteers), date of start of trial, date of end of the trial in the UK, European Union member states (if applicable) and globally (if applicable), date of start and end of recruitment, justification of deferral.
[14]S.I. 2025/538, Regulation 25(6)–(8).
[15]S.I. 2025/538, Regulation 25(10). In accordance with the HRA Guidance (Deferrals in Phase 1 trials - Health Research Authority, accessed on 7 July 2026), “If a sponsor submits a Phase 1 clinical trials of investigational medicinal product (CTIMP) application only involving healthy volunteers from 28 April 2026, it is automatically deferred for all transparency requirements. This means a sponsor is not required to include a written request for a deferral as part of the application.”
[16]S.I. 2025/538, Regulation 25(11).
[17]S.I. 2025/538, Schedule 14 (Transitional provisions).
[18]The state of the art comprises everything made available to the public by means of a written or oral description, by use, or in any other way, before the relevant priority/filing date of the European patent application.
[19]Case Law Book, 11th Edition, II.C.4.1 and I.C.7.2.2.
