The Medicines and Healthcare products Regulatory Agency (MHRA) has approved donidalorsen (Dawnzera) for use in patients aged 12 and over with hereditary angioedema (HAE), providing a new option to help prevent potentially life‑threatening attacks.
The decision, announced on 7 May 2026, marks an important advance for patients living with this rare genetic condition, offering improved control of symptoms and enhanced quality of life.
Hereditary angioedema (HAE) is a rare inherited disorder caused by a deficiency or dysfunction of the C1 inhibitor protein.
The condition leads to episodes of severe swelling in different parts of the body, including:
- Hands, feet and face
- The digestive system, causing painful abdominal symptoms
- The throat, where swelling can become life‑threatening by blocking the airway
Attacks are often unpredictable and can significantly impact patients’ daily lives, making effective prevention a key priority in treatment.
Donidalorsen works by targeting the biological pathway that drives swelling in HAE.
It inhibits the production of plasma kallikrein, a protein involved in generating bradykinin, which is responsible for increasing blood vessel permeability and causing swelling.
By reducing bradykinin levels in the bloodstream, the treatment helps prevent the development of angioedema attacks.
The medicine is administered as a subcutaneous injection using a pre‑filled pen, allowing treatment to be delivered at regular intervals.
The MHRA’s approval is based on evidence from a key clinical study involving 91 patients aged 12 and over with hereditary angioedema.
Participants received either:
- Donidalorsen every 4 weeks
- Donidalorsen every 8 weeks
- A placebo
After 24 weeks, results showed a substantial reduction in the number of attacks:
- Around 0.4 attacks per month for patients receiving the treatment every 4 weeks
- Around 1 attack per month for those treated every 8 weeks
- Compared with around 2.3 attacks per month for patients receiving placebo
These findings demonstrate a clear improvement in disease control for patients using donidalorsen.
In addition to reducing attack frequency, the treatment was shown to improve patients’ quality of life, based on validated assessments that measure how symptoms affect everyday activities.
By reducing both the frequency and severity of attacks, the therapy may help patients regain confidence, independence and stability in their daily lives.
Donidalorsen is given as a regular injection under the skin, offering a convenient option compared with treatments that may require hospital supervision.
Dosing schedules can be tailored, with injections administered either every four or eight weeks depending on clinical need and patient response.
The most common side effects reported with donidalorsen include reactions at the injection site, such as redness, swelling, pain, itching, bruising or changes in skin colour.
Some patients may also experience changes in liver function, which can be detected through routine blood tests.
Clinicians will monitor patients regularly to manage any side effects and ensure safe use of the treatment.
The approval of donidalorsen provides an important new option for managing hereditary angioedema, particularly for patients who experience frequent or severe attacks.
Julian Beach, Executive Director of Healthcare Quality and Access at the MHRA, commented:
“This approval provides a new treatment option for patients aged 12 years and older living with hereditary angioedema, an inherited condition that can cause recurrent swelling attacks and significant impact on daily life.
“As with all medicines, we will continue to closely monitor the safety and effectiveness of donidalorsen as it is used more widely.”
For people living with HAE, preventing attacks is critical, as episodes can be both debilitating and potentially life‑threatening.
The introduction of donidalorsen is expected to contribute to improved long‑term outcomes, reducing the burden of disease and helping patients lead more stable and active lives.
Image credit: iStock
