MHRA Guidance on First-in-Human Studies in the UK

Published on 22/12/2025

First-in-Human Clinical Trials in the United Kingdom: MHRA Guidance

First-in-human (FIH) studies mark a pivotal step in the clinical development of investigational medicinal products. These early-phase trials are conducted after preclinical evidence suggests acceptable safety, typically involving healthy volunteers or carefully selected patient groups. In the United Kingdom (UK), the Medicines and Healthcare products Regulatory Agency (MHRA) provides specific guidance for the design, approval, and oversight of FIH studies, emphasising participant safety, risk minimisation, and robust scientific justification. The UK’s established network of accredited Phase 1 clinical pharmacology units, combined with NHS and academic partnerships, has positioned the country as a leading destination for early clinical development programmes.

This guide examines MHRA requirements for FIH studies in the UK, covering regulatory submissions, safety monitoring, ethical considerations, and operational best practices for sponsors, CROs, and investigators.

Table of Contents

Background and Regulatory Framework

Legal Basis for FIH Studies

FIH trials in the UK are regulated under the Medicines for Human Use (Clinical Trials) Regulations 2004, aligned with ICH E6(R2) GCP. Sponsors must obtain a Clinical Trial Authorisation (CTA) from MHRA and favourable opinion from a Research Ethics Committee (REC).

MHRA Guidance Documents

MHRA guidance on risk-adapted approaches, trial design, and safety escalation

outlines the standards expected for FIH studies. This includes dose escalation strategies, sentinel dosing, and safety stopping rules.

Post-Brexit Context

Following Brexit, MHRA operates independently from the EU’s Clinical Trial Regulation but continues to align with ICH and EMA guidance to ensure international credibility of UK FIH data.

Core Insights into First-in-Human Trials

1. Clinical Trial Authorisation (CTA)

Sponsors must submit detailed CTAs including pharmacology, toxicology, and quality data. The Investigational Medicinal Product Dossier (IMPD) must justify the starting dose, escalation plan, and safety parameters.

2. Dose Escalation and Sentinel Dosing

MHRA recommends careful dose escalation protocols, beginning with single-dose sentinel cohorts before enrolling additional participants. Safety reviews between cohorts are mandatory.

3. Safety Monitoring

Continuous monitoring of vital signs, laboratory data, and adverse events is required. Independent Data Monitoring Committees (IDMCs) are often established for complex or high-risk studies.

4. Accredited Phase 1 Units

FIH studies must be conducted in MHRA-accredited clinical pharmacology units with immediate access to resuscitation and intensive care facilities.

5. Risk Mitigation Strategies

Protocol design must incorporate stopping rules, dose-limiting toxicity criteria, and clear risk mitigation pathways. This is especially important for biologics, gene therapies, and first-in-class drugs.

6. Ethical Oversight

RECs assess informed consent documents to ensure participants understand risks, including the limitations of preclinical data. Transparency and voluntariness are emphasised.

7. MHRA Inspections

MHRA inspects FIH sites for GCP compliance, focusing on dose escalation records, data integrity, pharmacovigilance procedures, and TMF documentation.

Best Practices for FIH Studies in the UK

Develop robust IMPD packages with transparent toxicology-to-clinic justification.
Implement adaptive dose escalation protocols with sentinel dosing.
Ensure accredited Phase 1 units have full resuscitation capacity.
Use independent safety monitoring committees for high-risk products.
Maintain full TMF compliance with real-time documentation of safety reviews.

Scientific and Regulatory Evidence

MHRA Guidance on Risk-Adapted Approaches
Medicines for Human Use (Clinical Trials) Regulations 2004
ICH E6(R2) – Good Clinical Practice
ICH M3(R2) – Nonclinical Safety Studies
EMA Guidance on FIH Dose Escalation Strategies

Special Considerations

Oncology FIH Trials: Often conducted in patients rather than healthy volunteers due to toxicity concerns.
Biologics and ATMPs: Require enhanced risk management, long-term follow-up, and complex safety monitoring.
Pediatrics: Rarely included in FIH trials; subsequent trials may require bridging strategies.
Decentralised Models: Limited applicability; most FIH studies require controlled clinical pharmacology units.

When Sponsors Should Seek Regulatory Advice

When developing novel biologics, ATMPs, or high-risk first-in-class products.
If dose escalation involves complex adaptive or Bayesian models.
When integrating biomarker-driven endpoints into FIH protocols.
For multinational FIH programmes requiring harmonisation with FDA and EMA.
If REC raises ethical concerns regarding participant consent or risk disclosure.

FAQs

1. What approvals are needed for FIH trials in the UK?

A Clinical Trial Authorisation from MHRA and REC approval are required before trial initiation.

2. How are starting doses determined?

Based on preclinical toxicology, pharmacokinetics, and safety margins, documented in the IMPD.

3. What is sentinel dosing?

The practice of dosing a small number of participants initially, with safety review before dosing additional subjects.

4. Are Phase 1 units in the UK accredited?

Yes. MHRA accredits Phase 1 units conducting FIH trials, ensuring facilities meet safety standards.

5. How does MHRA monitor safety during FIH trials?

Through CTA submissions, safety reporting, and routine GCP inspections of trial sites and pharmacology units.

6. Can FIH trials be conducted in rare diseases?

Yes, when ethical, typically involving small patient cohorts with high unmet need rather than healthy volunteers.

7. What are common MHRA inspection findings in FIH trials?

Inadequate safety stopping rules, incomplete TMF documentation, and poor justification of starting doses.

Conclusion

First-in-human trials in the UK are tightly regulated, requiring robust protocols, MHRA authorisation, and REC approval. Accredited Phase 1 units, combined with strong pharmacovigilance practices, ensure participant safety while enabling early clinical development. Sponsors must adopt comprehensive risk mitigation, maintain GCP compliance, and engage proactively with regulators. With MHRA’s rigorous oversight and NHS-supported infrastructure, the UK continues to be a leading destination for FIH studies, contributing to global drug development pipelines.