MHRA writes to King's on PATHWAYS puberty blocker trial

If you’re trying to work out what changed this week, here’s the short version we can build on together. On 20 February 2026, the UK regulator (the MHRA) said it has paused preparations for the PATHWAYS clinical trial and opened formal talks with King’s College London after raising concerns about participant wellbeing. Recruitment won’t begin until those issues are addressed. This is about safeguarding children and young people before any study starts. (gov.uk)

The MHRA’s public statement on GOV.UK framed this as the usual process for complex studies: trials are kept under continuous review and the regulator has active ‘scientific dialogue’ with sponsors. In plain English, that means experts from both sides sit down with the protocol, the safety data and the law, and work through what must change. It’s not a courtroom; it’s a technical conversation designed to reduce risk and improve study design. (gov.uk)

So what is PATHWAYS? It’s a planned randomised controlled trial looking at puberty blockers (GnRH analogues) for young people with gender incongruence. Participants would be randomly assigned either to start treatment straight away or after a set delay, so researchers can compare outcomes. The study is led by King’s College London, co‑sponsored with South London and Maudsley NHS Foundation Trust, and funded through the National Research Collaboration Programme with NIHR oversight. (kcl.ac.uk)

Alongside the public statement, the MHRA wrote to the sponsor on 11 February 2026 inviting a meeting to discuss specific amendments to the protocol. The letter says the regulator is taking a cautious approach because of the age of potential participants and lists areas where it wants stronger safeguards before any young person is enrolled. The MHRA also asked that the Health Research Authority (HRA) join the discussions. (assets.publishing.service.gov.uk)

One proposed change is a clear minimum entry age. The draft amendment the MHRA set out would require participants to be 14 or over at the time of consent. The letter also points to the need for an explicit ‘exit strategy’ if a participant finishes the study but continues on puberty blockers, with ongoing data collection on benefits and harms, reflecting advice previously given to ministers by the Commission on Human Medicines (CHM). (assets.publishing.service.gov.uk)

Safety monitoring is another focus. The MHRA outlines strengthened checks and potential withdrawal rules, including routine bone health assessments such as DEXA scans, clear criteria for stopping if there are worrying changes or fractures, careful management of vaginal bleeding, and extra review if cognitive tests or brain imaging flag problems. In short, the regulator wants predefined ‘stop points’ to prevent avoidable harm. (assets.publishing.service.gov.uk)

It also helps to know the policy backdrop. Since 2024, the government has restricted the sale and supply of puberty blockers to under‑18s outside NHS pathways, with ministers later confirming that ban would be made indefinite on expert advice. Those rules still allow for research-if it is tightly overseen. That’s why the MHRA is pressing for stronger guardrails now, before anyone is recruited. (gov.uk)

If you’re studying clinical ethics, this is a useful live example. In UK drug trials (CTIMPs), under‑16s cannot give consent for themselves; a parent or legal representative must consent, and young people should still be involved and heard. Over‑16s are usually able to consent, but their capacity should be assessed and families involved as appropriate. The HRA’s guidance stresses clear information, proportionate risk, and the right to withdraw at any point. (hra.nhs.uk)

A quick media‑literacy note for your classroom or seminar: ‘paused’ does not mean ‘cancelled’. The Department of Health and Social Care says PATHWAYS will not start recruiting until the MHRA and the sponsor resolve the concerns raised. Expect to see meetings, revised paperwork and, if the regulator is satisfied, an updated protocol before anything moves forward. That step‑by‑step scrutiny is normal in research with children. (gov.uk)

Where does this leave you if you’re following the story for school, university or practice? Watch for three signals: confirmation of the agreed minimum age, publication of clearer withdrawal and monitoring rules, and news that the HRA and MHRA are content with the revised protocol. We’ll keep explaining the jargon as it appears, so you can judge claims you see online against what the regulator and sponsor have actually said on the record. (gov.uk)