On 20 February 2026, the Medicines and Healthcare products Regulatory Agency (MHRA) confirmed it had raised participant‑wellbeing concerns about the PATHWAYS paediatric clinical trial and opened formal scientific dialogue with the sponsor, King’s College London. Given the age of prospective participants, the agency said it is applying heightened scrutiny. (gov.uk)
The Department of Health and Social Care (DHSC) subsequently stated that preparations for the study have been paused and that recruitment will not begin until the issues identified by the regulator are resolved between MHRA and the trial clinicians. (gov.uk)
A four‑page MHRA letter to the sponsor invites discussion of amendments to the clinical protocol. The correspondence proposes introducing a minimum enrolment age and, as a precautionary first phase, starting eligibility at 14, with any later reduction dependent on initial findings. (assets.publishing.service.gov.uk)
Beyond the age change, the MHRA outlines strengthened safety monitoring and explicit stop rules. Proposals include more granular bone‑health surveillance using DEXA scanning, discontinuation criteria linked to low‑trauma fractures, management and escalation of care where vaginal bleeding persists beyond two weeks, and withdrawal triggers where cognitive effects are detected on imaging. (assets.publishing.service.gov.uk)
The letter also asks for a clear exit strategy for participants who may continue gonadotrophin‑releasing hormone analogue treatment after the study, aligning with earlier expert advice to ministers that under‑18 private supply of these medicines should be restricted outside research settings. (assets.publishing.service.gov.uk)
According to King’s College London, PATHWAYS is a randomised controlled trial comparing immediate initiation of puberty‑suppressing hormones with initiation after 12 months. The study is led by King’s, co‑sponsored with South London and Maudsley NHS Foundation Trust, funded through the National Research Collaboration Programme, and overseen by independent data and steering committees. (kcl.ac.uk)
Prior reporting suggested a target enrolment of around 226 children and young people, with the originally envisaged lower age bands aligned to early puberty stages. If implemented, the regulator’s proposed 14‑and‑over threshold would materially reshape the cohort and study timelines. (theguardian.com)
The Health Research Authority (HRA) has confirmed that, because the study has been paused, the Research Ethics Committee will re‑review the protocol in line with its standard procedures. Any amendments arising from MHRA’s scientific dialogue must secure REC approval before recruitment can commence. (hra.nhs.uk)
This intervention sits within a wider policy framework that, since 1 January 2025, has indefinitely restricted the sale and supply of puberty blockers to under‑18s other than within NHS pathways or accredited clinical trials, following advice from the Commission on Human Medicines and the Cass Review. (gov.uk)
For research teams, near‑term tasks are technical: adjust inclusion criteria and stop rules, update participant information and consent materials, reassess sample size and monitoring schedules, and secure approvals before site activation. For families, the position is unchanged for now: recruitment will not proceed until regulators and investigators conclude the protocol is safe and justified. (hra.nhs.uk)