UK Approves First Puberty Blocker Trials for Children Following Ban

New Clinical Trials Launched

Regulators in the United Kingdom have approved the commencement of the first clinical trials for puberty-blocking drugs in children, marking a significant development since the routine prescription of these medications was halted. The trials, primarily the 'Pathways Trial' and 'Pathways Connect', are being led by King's College London and aim to gather robust evidence on the effects of puberty suppressants in young people experiencing gender incongruence.

This initiative follows the comprehensive Cass Review, an independent assessment of NHS gender identity services for children and young people, which concluded in April 2024. The review, led by Dr. Hilary Cass, found that the evidence base for the use of hormone treatments in children was 'remarkably weak' and recommended that puberty blockers should only be available within a research protocol.

Context of the Previous Ban

In March 2024, NHS England announced it would no longer routinely prescribe puberty blockers to under-18s at gender identity clinics, citing insufficient evidence to support their safety or clinical effectiveness. This decision was informed by an evidence review conducted by the National Institute for Health and Care Excellence (NICE) and the interim findings of the Cass Review. The government subsequently made this ban permanent in December 2024, extending restrictions to private prescriptions for under-18s not already receiving them.

The move to restrict access to puberty blockers outside of research settings was a direct response to concerns about the lack of long-term data on their impact on psychological well-being, cognitive development, and fertility. Referrals to gender services had seen a sharp increase, rising from 210 per year in 2011 to over 5,000 per year by 2022, according to the Cass Review.

Details of the Approved Trials

The 'Pathways Trial' is designed as a clinical study that will recruit an estimated 226 young people over the next three years. Participants, who must be under 16 years old, have experienced at least two years of 'gender incongruence,' and have started puberty, will be randomized into two groups: one receiving puberty-suppressing drugs immediately alongside non-medical care, and another receiving non-medical care alone for a year before potentially starting blockers. Consent from at least one parent or guardian is required, and participants will be followed for two years.

A second study, 'Pathways Connect,' will focus on the brain health of a subset of children from the main trial, as well as a control group not receiving puberty blockers. Researchers will use MRI brain imaging to assess their developing brains and evaluate thinking and brain health.

The trials are part of a wider 'Pathways' programme, funded with over £10 million from the National Institute for Health and Care Research (NIHR). Recruitment is expected to begin soon, with results not anticipated for at least four years. These trials represent the world's first randomized clinical trial of puberty blockers for gender incongruence in youth.

Objectives and Future Implications

The primary objective of these trials is to provide a stronger evidence base to help young people and their families make informed decisions about treatment options. The studies will closely monitor the quality of life, physical, and mental health of participants. While some doctors' groups have expressed concerns about the potential harms of the drugs, transgender groups argue that the current medical establishment has downplayed the benefits of gender-affirming care.

The findings from these trials are expected to significantly influence future policies and clinical practices regarding gender identity services for children and adolescents in the UK.