UK MHRA CTR 2024: the redesigned clinical-trials regulatory stack

Layer 0 is statutory framework reform — the 2024 amendment regulations modify the 2004 Regulations rather than wholesale replace them. Layer 1 is combined MHRA + HRA review embedded legally — a single application via the Integrated Research Application System (IRAS) returns a single decision within a target timeframe (combined target ~30 days standard, extendable for complex submissions and Advanced Therapy Medicinal Products). Layer 2 is risk-proportional categorisation — Type A trials (drugs/uses considered no higher risk than standard medical care, e.g., comparative effectiveness of well-established treatments) operate under a notification scheme; Type B trials (moderate risk, including most Phase II/III on licensed drugs) operate under expedited review; Type C trials (higher risk, including first-in-human, novel mechanism, novel ATMPs) operate under full review with potentially more extensive data requirements. Layer 3 is transparency — mandatory registration on a public registry within 28 days of authorisation, mandatory publication of trial results within 12 months of trial end. Layer 4 is diversity-and-inclusion — sponsors must consider participant diversity at protocol design with documented rationale, with NHS HRA guidance on inclusive recruitment.

MHRA Clinical Trials Authorisation (CTA) and HRA Research Ethics Committee (REC) opinion combine in a single IRAS submission with parallel review and a single combined decision. The combined review pilot ran 2018-2023 and is now legally embedded. Sponsor submits via IRAS with the protocol, IB/IMPD, ICF, patient-facing materials, GCP qualifications, insurance/indemnity and the new diversity/transparency components. MHRA reviews CTA aspects; HRA REC reviews ethics aspects; combined decision returns to sponsor. For complex trials (ATMPs, gene therapy, novel mechanisms), Scientific Advice Meetings with MHRA + NICE + HRA are encouraged pre-submission. Combined review applies to all trial Types A/B/C with different review depth.

Type A trials — drugs/uses where the risk is no higher than that of standard medical care: typically licensed drugs used within or close to their licensed indication, with established safety profile. Type A operates under a notification pathway with simplified documentation and faster decision. Type B trials — moderate risk: most Phase II/III trials of licensed drugs, off-label use studies, comparator-controlled studies, with expedited review and proportional documentation. Type C trials — higher risk: first-in-human, novel mechanism, novel ATMPs, paediatric, vulnerable populations, with full review and complete documentation. Sponsor proposes the trial type at submission with justification; MHRA confirms or recategorises. Pharmacovigilance, SUSAR reporting, safety updates and inspection-risk apply proportionally.

Mandatory transparency: within 28 days of combined authorisation, the trial must be registered on a recognised public registry (ISRCTN, ClinicalTrials.gov, EU CTIS or EudraCT for legacy trials, with a UK-recognised registry list). Within 12 months of trial end (last patient last visit), summary results must be published on the registry — including primary and secondary outcomes, adverse events, and (for paediatric trials) lay summary. Failure to register or publish results may affect future trial authorisations and is a public-facing transparency record. Aligns broadly with EU CTR Article 37 publication requirements but with UK-specific timeline and registry rules.

The 2024 reform embeds diversity-and-inclusion in trial design as a regulatory requirement. Sponsors must consider participant diversity (ethnicity, sex, age, comorbidities, geography, socioeconomic factors) relative to the target patient population for the intended use, with documented rationale. HRA published guidance on inclusive trial design including recruitment strategy, language accessibility (Welsh requirements where applicable), site selection beyond traditional academic centres, and inclusive consent processes. The diversity rationale and recruitment plan become part of the IRAS submission and inspection-readiness documentation. Sponsors are not required to achieve specific demographic distributions but must demonstrate considered design and good-faith implementation.

EU Regulation 536/2014 (EU CTR) is administered via the Clinical Trial Information System (CTIS) since January 2023. UK exited the EU CTR transition January 2023. The 2024 UK reform converges with EU CTR on some principles (combined review, transparency, single submission) but diverges on: (a) submission system (IRAS vs CTIS), (b) review timeline targets and procedure, (c) risk-categorisation specifics (UK Type A/B/C is novel; EU CTR uses different risk language), (d) transparency timelines and registry choice, (e) diversity requirements (UK-specific). Sponsors running UK + EU trials must run dual processes — there is no UK-EU mutual recognition for clinical trial authorisation. Some pragmatic alignment: shared protocol, harmonised IB/IMPD, common ICF base with country-specific amendments.

Map the trial portfolio against Type A/B/C and revise SOPs to reflect proportional regulation. Update IRAS submission templates with the 2024 reform elements (transparency plan, diversity plan, trial type justification). Establish a transparency-registration workflow with 28-day-from-authorisation and 12-month-from-end deadlines tracked centrally. Update diversity-in-design protocols and recruitment plans. For dual UK/EU trials, run parallel CTIS + IRAS submission tracks with shared core documentation. Train sites and CROs on the combined review timeline expectations. Watch MHRA implementation guidance through 2025-2026 transition.