MHRA approves Otsuka’s Dawnzera (donidalorsen) for preventing hereditary angioedema attacks in patients aged 12 and older, backed by OASIS-HAE data showing up to 81% attack reduction versus placebo.
Written By: Sana Khan BPharm
Reviewed By: Pharmacally Editorial Team
The UK Medicines and Healthcare products Regulatory Agency (MHRA) has approved donidalorsen, marketed as Dawnzera, for preventing hereditary angioedema (HAE) attacks in patients aged 12 years and older.
The approval was granted on May 7, 2026, to Otsuka Pharmaceutical Netherlands B.V. through the MHRA’s International Recognition Procedure (IRP).
The UK authorization follows regulatory progress for donidalorsen in other major markets, including the US and Europe, as plasma kallikrein-targeting therapies continue to expand treatment options for HAE patients.
HAE is a rare inherited disorder caused by deficiency or dysfunction of the C1 inhibitor protein. The disease causes recurrent swelling attacks affecting the abdomen, extremities, and airways. Throat swelling can become life-threatening due to airway obstruction.
Donidalorsen is an RNA-targeted therapy that inhibits plasma kallikrein production, reducing bradykinin levels that drive HAE attacks. The treatment is administered as a subcutaneous injection using a pre-filled pen.
The approval was supported by data from the pivotal OASIS-HAE study (NCT05139810) involving approximately 90 patients aged 12 years and older. Participants received donidalorsen every four weeks, every eight weeks, or placebo over 24 weeks.
Patients treated every four weeks reported a mean attack rate of 0.44 attacks per month, representing an 81% reduction versus placebo. Patients receiving treatment every eight weeks reported 1.02 attacks per month, reflecting a 55% reduction compared with placebo. The placebo group reported an average of approximately 2.3 attacks per month.
The study also showed improvements in patient quality of life based on validated assessments measuring the impact of HAE symptoms on daily activities.
Julian Beach, Executive Director of Healthcare Quality and Access at the MHRA, said the approval provides an additional treatment option for patients living with hereditary angioedema, a condition associated with recurrent swelling attacks and substantial daily burden. He added that the agency will continue monitoring the medicine’s safety and effectiveness following broader clinical use.
The most common adverse events included injection-site reactions such as redness, pain, itching, bruising, swelling, skin discoloration, and bleeding under the skin. Liver-related laboratory abnormalities and hypersensitivity reactions, including allergic reactions, were also reported. Long-term safety monitoring will continue as the therapy becomes more widely used.
Reference
MHRA approves donidalorsen (Dawnzera) for the treatment of hereditary angioedema – GOV.UK
Marc A. Riedl et al, Efficacy and Safety of Donidalorsen for Hereditary Angioedema, N Engl J Med 2024;391:21-31, https://www.nejm.org/doi/full/10.1056/NEJMoa2402478
About the Writer
Sana Jamil Khan (LinkedIn) is a B. Pharm graduate with a strong interest in medical writing and scientific communication. Her work focuses on interpreting clinical research, exploring developments in pharmaceutical science, and presenting complex medical information in a clear and accessible manner. She is particularly interested in topics related to human clinical studies, drug safety observations, and emerging therapeutic research.