On 7 January 2026, the Medicines and Healthcare products Regulatory Agency (MHRA) approved nirogacestat hydrobromide (Ogsiveo) for treating progressing desmoid tumours in adults. The authorisation was granted via the International Recognition Procedure (IRP), with the European Medicines Agency as the Reference Regulator (EMEA/H/C/006071/0000).
Desmoid tumours are connective‑tissue growths that typically occur in the arms, legs or abdomen. While not cancerous, they can infiltrate nearby tissue as they enlarge and may be difficult to remove surgically, according to the MHRA.
Nirogacestat hydrobromide works by inhibiting proteins involved in tumour growth. The MHRA reports that study participants receiving the medicine lived longer without their condition worsening and were more likely to avoid potential surgery.
Julian Beach, the MHRA’s Interim Executive Director for Healthcare Quality and Access, said the decision should improve health and quality of life for affected adults, while emphasising that patient safety remains paramount. The agency confirmed it will continue to monitor safety and effectiveness for this licensed medicine.
According to the regulator, common adverse reactions include diarrhoea, rash, nausea, tiredness, hypophosphataemia, headache and stomatitis. Premature menopause is highlighted as a serious side effect that may affect more than one in ten people.
The medicine must not be taken during pregnancy. The MHRA states that nirogacestat hydrobromide may harm an unborn baby, and highly effective contraception must be used because potential effects on ovaries, testicles and overall fertility in men and women remain uncertain.
To support pregnancy prevention, a patient card will be provided to female patients taking the medicine and to female partners of male patients. The card sets out key risks and the measures that must be followed to minimise potential harm.
A full list of side effects and detailed prescribing information will be available in the Patient Information Leaflet and the Summary of Product Characteristics, which the MHRA says will be published on its Products website within seven days of approval.
Patients, carers and clinicians are encouraged to discuss any suspected side effects with a healthcare professional and report them via the MHRA Yellow Card scheme. Reports can be submitted through the website or by using the MHRA Yellow Card apps available from the Apple and Google Play stores.
As with other IRP approvals, the MHRA retains responsibility for post‑authorisation surveillance in the UK. The regulator reiterates that safety and effectiveness will be monitored continuously for Ogsiveo alongside routine Yellow Card reporting.