UK Substantial Modifications Pilot

The MHRA Clinical Trials Unit ran a Route B substantial modifications pilot from 1 October 2025 to 31 March 2026. The aim was to test a streamlined review process for changes to already approved clinical trials eligible under section 11B of the 2024 amended regulations. The pilot's goal was to reduce review timelines from 35 days to 14 days by lowering administrative burden for low-risk trials while allowing assessors to focus on higher-risk work.

Outcome

By the end of March, the MHRA received 94 registrations (split almost equally between commercial and non-commercial sponsors) and 26 applications from industry and academia. The average processing time from start to finish was seven days, beating the target of 14 days, and the feedback from the research community was positive, including repeat submissions from major global pharmaceutical companies.

The pilot has made refinements to the process (in terms of both form and guidance) and is supporting readiness for the full Route B implementation. Route B is supposed to become legally mandated under the new UK Clinical Trials Regulations, which became effective on 28 April 2026.

For more Information please see the MHRA Inspectorates Blog.