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A minimum age of 11 years has been set for participation in the ‘PATHWAYS’ clinical trial, which will look at the benefits and risks of puberty suppressants in children and young people with gender incongruence.
In a statement published on 19 June 2026, the Medicines and Healthcare products Regulatory Agency (MHRA) said that a modified protocol had been agreed following discussions with the trial sponsors — King’s College London (KCL) and South London and Maudsley NHS Foundation Trust.
“The modified protocol includes strengthened safeguards including the introduction of minimum ages of entry to the trial and more clearly defined discontinuation measures around safety for bone health, cognition and vaginal bleeding, as well as more detailed information for participants on fertility preservation,” it said.
The statement added that the Health Research Authority (HRA) has approved the trial for its ethical standards.
The original trial protocol, published on 20 November 2025, stated that to be eligible, participants should be aged younger than 15 years and 11 months.
According to an updated protocol published on 4 June 2026, birth-registered females must be aged between 11 and 16 years to be eligible for inclusion. Birth-registered males must be aged between 12 and 16 years to participate in the trial, it said.
The announcement follows a letter sent to KCL on 20 February 2026, where the MHRA stated that it “would like to discuss the inclusion of a minimum age for participation in the trial” and also suggested other amendments.
The MHRA added that recruitment to the trial has been paused until 1 August 2026 owing to legal proceedings.
Jonathan Montgomery, professor of healthcare law at UCL, commented: “It is good that the MHRA and HRA have completed their reviews of the scientific and ethical concerns that have been raised with them about the PATHWAYS clinical trial promptly.
“They have ensured that a modified protocol is in place prior to recruitment. It is encouraging that full regulatory oversight has been possible without unduly delaying the trial. Legal proceedings are expected to provide further scrutiny.”
In a letter sent to colleagues on 11 March 2026, Lawrence Tallon, chief executive of the MHRA, said that the scientific dialogue between the trial sponsors, MHRA and other stakeholders “is not so unusual”.
“It is not uncommon for complex clinical trials to go through stages of iteration. What is highly unusual in this case is the level of public, media and legal attention,” he added.
Tallon continued: “As an agency, we are in a mature and collegiate scientific dialogue with the trial sponsors at KCL, and I am grateful to them for the way in which they have entered into these discussions.
“These are highly regarded, experienced and principled clinician-scientists who are doing their best to support the current and future needs of young people with gender dysphoria. Their scientific credibility and principled motivations are not in doubt.”
