MHRA sets terms for UK trials built on non-clinical data from outside the OECD system

The Medicines and Healthcare products Regulatory Agency (MHRA) published guidance on 4 November 2026 setting out how it will treat UK clinical trial applications that lean on non-clinical safety data produced outside the OECD Mutual Acceptance of Data framework¹. The agency presents the move as a patient-centred, risk-proportionate step intended to widen UK patients' access to trials and to support the development of new treatments¹.

What the guidance says

The default does not move. Data generated inside the OECD system, which follows agreed testing standards and Good Laboratory Practice, remain the expected basis for a UK trial application, and the MHRA calls the framework "an internationally recognised approach" to producing non-clinical safety evidence¹.

What changes is that the MHRA now explains when it may look at data from outside that system in an individual application. It will do so where the available evidence and the circumstances of the intended patient population justify further consideration¹. The agency will weigh the non-clinical package against the features of the proposed study¹:

• the participant population
• how serious the condition is
• the level of unmet medical need
• the stage and design of the trial

In limited cases the MHRA may run an enhanced non-clinical assessment. Its named example is first-in-human trials in patients with advanced cancers, or with other serious or life-threatening conditions where unmet need is significant¹. The agency describes this as extra scientific scrutiny applied where appropriate, so the route is framed as closer examination of the evidence rather than a lighter touch¹.

Alongside case-by-case review, the MHRA will run a strategic, risk-based inspection programme covering non-clinical test facilities that appear frequently in UK trial applications¹. The findings will feed into later assessments and oversight¹.

What it means for the market

The guidance matters most to sponsors whose early safety packages come from laboratories that sit outside the OECD system. Until now those developers had no published account of how the MHRA would treat such data. They now have stated criteria, a defined setting in which an enhanced assessment may apply, and an instruction to talk to the agency before filing¹.

The emphasis on first-in-human oncology and serious conditions points to where the MHRA expects the route to be used. For trial sponsors weighing the UK as a site for early studies, that clarity is the practical gain. The inspection programme matters to the facilities themselves: those named often in UK applications can expect to be examined, and the results will shape how their data are judged in future¹.

The MHRA does not say how many applications it expects under this approach, which facilities or countries are in scope, or how long an enhanced assessment will take. Its announcement leaves those points to the full guidance and to early discussion with the agency¹.

Limits

The agency is explicit that the standards for the quality, safety and integrity of the main non-clinical safety data supporting an application are unchanged¹. Consideration of non-OECD data is case by case and depends on the evidence and the patient population, so there is no general acceptance¹. The MHRA also says the approach will evolve with regulatory experience, compliance intelligence and the outcomes of its facility inspections¹.

Developers that plan to rely on non-clinical data from outside the OECD Mutual Acceptance of Data system are told to engage with the MHRA early, before they submit a clinical trial application¹.