MHRA authorises donidalorsen for hereditary angioedema prevention
Brian Attwood | May 27, 2026 | News story | Research and Development |Â Â donidalorsenÂ
Otsuka Pharmaceuticals UK announced that the Medicines and Healthcare products Regulatory Agency (MHRA) has authorised Dawnzera (donidalorsen) for routine prevention of recurrent hereditary angioedema (HAE) attacks in adults and adolescents aged 12 years and older.
HAE is a rare inherited condition characterised by unpredictable episodes of swelling affecting areas including the face, abdomen, extremities and throat. Attacks involving the airway can become life-threatening without urgent treatment. In the UK, the condition affects an estimated one in 59,000 people.
The MHRA decision was based on results from the phase 3 OASIS-HAE trial involving 90 patients. The study met its primary endpoint, showing that patients receiving donidalorsen every four weeks experienced an 81% reduction in attack rate compared with placebo over 24 weeks.
Patients receiving treatment every eight weeks also showed reduced attack frequency compared with placebo.
Angela Metcalfe, Chief Executive of HAE UK, said the unpredictability of attacks could have a significant impact on patients’ daily lives and emotional well-being.
The study also found that most patients receiving donidalorsen achieved well-controlled disease status, according to Angioedema Control Test scores.
Common adverse events included injection-site reactions and increased hepatic enzymes, while hypersensitivity reactions including anaphylaxis were also reported.
Professor Sinisa Savic, Professor of Clinical Immunology at the University of Leeds, said HAE continued to present major long-term management challenges despite advances in treatment.
Donidalorsen is an antisense oligonucleotide (ASO) therapy administered subcutaneously. It works by reducing production of prekallikrein in the liver, targeting the biological pathway involved in HAE attacks.
Otsuka Pharmaceuticals UK said it would continue discussions with NICE and the NHS regarding access arrangements for eligible patients.
