MHRA Updates Guidance on Clinical Trials Requiring Expert Advice

10th October 2025

MHRA Updates Guidance on Clinical Trials Requiring Expert Advice

Summary: The Medicines and Healthcare products Regulatory Agency (MHRA) has published revised guidance on clinical trials requiring expert advice, effective from 28th April 2026. This updated guidance outlines the circumstances under which expert advice may be sought, including:

• Significant Safety Concerns: When the licensing authority has significant safety concerns about a novel compound being used in a UK trial for the first time.

• Novel Compounds: When the clinical trial uses a novel compound that acts via a cascade system with potential amplification effects not sufficiently controlled by physiological feedback mechanisms.

• Immune System Targets: When the clinical trial uses a novel compound that acts via the immune system with a novel or not well-characterised target or mechanism of action.

• Species-Specific Mechanisms: When the novel compound may act via a species-specific mechanism and animal models are unlikely to predict activity in humans.

The guidance also details the process for obtaining expert advice, including the submission of relevant information to the licensing authority and ethics committee. A flowchart summarising the process and maximum timelines for applications requiring expert advice is provided to assist sponsors in navigating the approval process.

Link: Clinical Trials for Medicines: Expert Advice

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