From 28 April 2026, sponsors of clinical trials of investigational medicinal products (CTIMPs) will need to register their trial on a public registry before they recruit their first participant or within 90 calendar days of the trial receiving approval - whichever is sooner.
In the context of the new clinical trial regulations, a 'public registry' is a primary or partner registry of, or a data provider to, the World Health Organization (WHO) International Clinical Trials Registry Platform.
The registry, or data provider, must also ‘facilitate public access’ to information about the trial in the United Kingdom (UK). This means that it must be possible for members of the public to identify and access information about trials in the United Kingdom.
Which trials this requirement applies to
Whether a trial will need to meet this legislative requirement will depend on when it’s submitted.
If a sponsor submits an application for clinical trial authorisation and an ethics committee opinion for a CTIMP from 28 April 2026, they must register it in line with the new legal requirements.
If a sponsor submits an application before 28 April 2026 and the trial’s end date is before this date, the new legislative requirements for trial registration will not apply to it. However, the sponsor would still need to register their trial in compliance with the conditions of the Research Ethics Committee (REC) favourable opinion given to the CTIMP.
If a trial was submitted before 28 April 2026, has an end date after 28 April 2026, and the sponsor has already registered it with either ISRCTN or ClinicalTrials.gov, the sponsor will have fulfilled this legislative requirement.
Trials submitted before 28 April 2026 that have not been registered by 28 April 2026 and have an end date at any point from this date must be registered in line with the new legal requirements.
In these cases, the point by which a sponsor needs to register will depend on whether the trial has already recruited a participant.
If the first participant has not yet been recruited
The sponsor must register for the trial within 90 calendar days of the new regulations coming into force (28 April 2026) or before they recruit the first participant - whichever is sooner.
If the first participant has already been recruited
The sponsor must register for the trial within 90 calendar days of the date the new regulations come into force (28 April 2026).
If the sponsor decides to abandon a clinical trial before any trial procedures set out in the protocol (for example, patient screening or consent) have begun and within 90 calendar days of the trial getting combined approval from the Medicines and Healthcare products Regulatory Agency (MHRA) and REC, then the sponsor won’t need to register the trial.
Public registries sponsors should use
The new legislation requires a sponsor to register a trial in a public registry.
Both ISRCTN and ClinicalTrials.gov are registries that would meet the definition of being a public registry under the amended regulations. Registering with either of these public registries would fulfil the requirements in the new regulations.
Both ISRCTN and ClinicalTrials.gov also feed into Be Part of Research, an online service run by the National Institute for Health and Care Research (NIHR). Be Part of Research helps members of the public understand what research is, what it might mean to take part, and what research is currently happening across the UK.
Although both registries meet the criteria of being a public registry, unless there is a U.S. Food and Drug Administration (FDA) requirement to register with ClinicalTrials.gov, sponsors should register with ISRCTN.
ISRCTN allows sponsors who register their trial with the registry to:
- publish a lay summary of their protocol
- add a plain language summary of the trials results
- fully register the trial or publish a minimal record if a trial has an agreed deferral
In addition the HRA has a partnership with the ISRCTN registry which means that the study information sponsors enter into the new part of IRAS as part of an initial trial application will be sent directly to ISRCTN for registration.
This can help simplify the registration of trials submitted through the Combined Review process.
If a sponsor wants to register their trial in more than 1 registry they can do so. If they do this, the sponsor should be aware that under the new regulations they would be required to publish a summary of their trial results in each registry they registered their trial with.
Registration with the EU Clinical Trials Information System (CTIS) will not satisfy the trial registration requirement in the new clinical trials regulations. This is because, although CTIS has been designated as a primary registry by WHO within the International Clinical Trials Registry Platform (ICTRP), it does not allow members of the public to identify trials taking place in the UK and therefore does not ‘facilitate public access’ to information about trials in the UK.
Similarly, previous registration with EudraCT will also not satisfy the trial registration requirement within the new regulations.
Any trials that are only registered through CTIS and/or EudraCT should also be registered on ISRCTN or ClinicalTrials.gov so the sponsor complies with the transparency requirement in the new regulations.
Registering a trial with public registries
If a sponsor submits an application in IRAS, we’ll share some basic information on the trial with ISRCTN to support its registration. This does not mean that the trial is registered with ISRCTN.
ISRCTN will contact the sponsor for additional details to complete the registration.
If the sponsor would prefer to register the trial with ClinicalTrials.gov rather than ISRCTN, they can tell us in their IRAS application (in 'Section C' of the Study Information section). If the sponsor lets us know in their application that they intend to do this, we'll not pass the trial details to ISRCTN.
What sponsors should do once a trial is registered
When the sponsor has completed the registration with ISRCTN, the HRA will automatically be informed.
If the sponsor has registered their trial with ClinicalTrials.gov, they should email the HRA at study.registration@hra.nhs.uk once they have completed the registration process. The sponsor will not need to email the HRA if they have registered their trial with ClinicalTrials.gov and specified they would do this in their initial IRAS submission.
Confirming the first UK participant has been recruited
Sponsors will need to confirm the date that the first UK participant in a trial is recruited to show that the trial was registered within the given timeframes. Sponsors will be able to do this by using the modification tool to submit a modification of an important detail which confirms the first recruitment has occurred
Requesting a deferral or waiver for this requirement
The sponsor can request a deferral or, in exceptional circumstances, a waiver. For further information, please see our guidance on the deferrals and waiver process for the transparency requirements in the new regulations.
If the trial is a Phase 1 CTIMP only involving healthy volunteers, it will automatically be given a deferral for the transparency requirements for 30 months after the end of the trial.