Interpretation guidance for MHRA regulatory considerations for phage therapeutic products

On 4 June 2025, the MHRA published 'Regulatory considerations for therapeutic use of bacteriophages in the UK'. This was in response to recommendations made by the House of Commons Science, Innovation and Technology Committee Inquiry into the 'The Antimicrobial Potential of Bacteriophages'. The MHRA Regulatory Considerations for phage therapeutic products (PTPs) outlines the relevant regulatory route and requirements to use PTPs as licensed or unlicensed medicines. While this guidance provides the necessary information, it is recognized that regulatory information can be inaccessible to academic and small- to medium-sized enterprise developers who are often unfamiliar with the language, terminology and location of such information. The MHRA, in consultation with the Innovate UK Phage Innovation Network, has therefore developed this interpretation to help PTP developers understand what the guidance is saying, and what evidence is required for regulatory assessment of a marketing authorization application. Examples have been included throughout to provide context and as an aid to understanding.