AstraZeneca drug gets EU panel nod for myasthenia

Rhea-AI Filing Summary

AstraZeneca PLC (AZN), through its Alexion Rare Disease unit, reports that the European Medicines Agency’s CHMP has recommended Klygefa (gefurulimab) for approval in the EU as an add-on treatment for adults with anti‑AChR antibody-positive generalised myasthenia gravis (gMG), based on the Phase III PREVAIL trial.

The study in 260 patients across 20 countries showed Klygefa met its primary endpoint, improving Myasthenia Gravis Activities of Daily Living (MG‑ADL) total score at week 26 versus placebo with a treatment difference of -1.6 (95% CI: -2.4, -0.8; p<0.0001), with clinically meaningful benefits seen from week one and sustained through week 26. If approved, Klygefa would be the first and only dual-binding nanobody C5 inhibitor for gMG in the EU, offering once‑weekly subcutaneous self-administration as an add-on to standard therapy, and was generally well-tolerated with a safety profile consistent with existing C5 inhibitors.

Positive

• CHMP positive opinion for Klygefa in EU gMG represents a key regulatory milestone that could add a new once‑weekly subcutaneous treatment option and expand AstraZeneca’s rare disease portfolio if formal approval follows.

Negative

• None.

Filing Explained

The filing adds that patients completing the PREVAIL trial may enter an ongoing open-label extension, while applications based on its results remain under review in the US, China and other countries; the EU recommendation has not yet become an approval.

Key Figures

gMG prevalence in 5 Europe countries: 82,500 people AChR antibody-positive gMG population: 66,000 people PREVAIL trial enrollment: 260 patients +3 more

6 metrics

gMG prevalence in 5 Europe countries 82,500 people Estimated number diagnosed with generalised myasthenia gravis in Germany, France, UK, Italy and Spain

AChR antibody-positive gMG population 66,000 people Estimated anti‑AChR antibody-positive gMG patients within the five European countries

PREVAIL trial enrollment 260 patients Adults with generalised myasthenia gravis across 20 countries in the Phase III PREVAIL study

MG‑ADL treatment difference at week 26 -1.6 points Change in Myasthenia Gravis Activities of Daily Living total score versus placebo; 95% CI: -2.4 to -0.8; p<0.0001

PREVAIL treatment period length 26 weeks Duration of the randomized controlled treatment period assessing Klygefa versus placebo

Klygefa dosing frequency Once weekly Subcutaneous maintenance dosing following a single loading dose in the PREVAIL trial

Key Terms

generalised myasthenia gravis, dual-binding nanobody C5 inhibitor, Myasthenia Gravis Activities of Daily Living (MG-ADL), complement system, +1 more

5 terms

generalised myasthenia gravis medical

"for the treatment of adults with generalised myasthenia gravis (gMG)"

dual-binding nanobody C5 inhibitor medical

"the first and only dual-binding nanobody C5 inhibitor for this patient"

Myasthenia Gravis Activities of Daily Living (MG-ADL) medical

"improvement in Myasthenia Gravis Activities of Daily Living (MG-ADL) total score"

Myasthenia gravis activities of daily living (MG-ADL) is an eight-item patient-reported measure that tracks how muscle weakness from myasthenia gravis affects everyday tasks such as speaking, chewing, swallowing, breathing and walking. Investors care because changes in MG-ADL are used in clinical trials and regulatory reviews to show whether a treatment delivers real, practical benefits to patients, influencing approval chances, physician adoption and market value — like a user satisfaction score for a therapy’s everyday usefulness.

complement system medical

"This binding activates the complement system, causing the immune system"

The complement system is a set of proteins in the blood that act together like a security alarm and cleanup crew for the body’s immune system: they detect threats, tag invaders for removal, and help destroy harmful cells. Investors should care because drugs or diagnostics that target or measure this system can affect treatment effectiveness, safety profiles, and market potential for therapies in immune, inflammatory, and rare disease areas.

open-label extension medical

"eligible to continue into an open-label extension period evaluating the safety"

An open-label extension is a continuation of a clinical trial where all participants and researchers know which treatment is being given, often after an initial blinded phase. It allows further study of a drug's long-term safety and effectiveness. For investors, it can indicate ongoing interest and confidence in a product's potential, influencing perceptions of its future value.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did AstraZeneca (AZN) announce about Klygefa in the EU?

AstraZeneca disclosed that the EMA’s CHMP issued a positive opinion recommending EU approval of Klygefa (gefurulimab) as an add-on therapy for adults with anti‑AChR antibody-positive generalised myasthenia gravis, based on results from the Phase III PREVAIL trial.

How effective was Klygefa in the PREVAIL Phase III trial reported by AZN?

In PREVAIL, Klygefa met its primary endpoint, improving MG‑ADL total score at week 26 versus placebo with a treatment difference of -1.6 (95% CI: -2.4, -0.8; p<0.0001). Clinically meaningful improvement was observed as early as week one and sustained through week 26.

What makes Klygefa potentially differentiated for gMG patients in the EU?

If approved, Klygefa would be the first and only dual-binding nanobody C5 inhibitor for generalised myasthenia gravis in the EU, designed for once‑weekly subcutaneous self-administration with rapid and sustained symptom control as an add-on to standard therapy.

How large is the generalised myasthenia gravis population relevant to AZN’s Klygefa in Europe?

The disclosure cites an estimated 82,500 people diagnosed with generalised myasthenia gravis across five major European countries, of whom about 66,000 are anti‑AChR antibody-positive, representing the target population for Klygefa in this indication.

What safety profile did AstraZeneca report for Klygefa in gMG?

Klygefa was reported as generally well-tolerated in PREVAIL, with a safety profile consistent with previous trials of C5 inhibitors eculizumab and ravulizumab in generalised myasthenia gravis, supporting its use as an add-on therapy for adults with anti‑AChR antibody-positive disease.

In which other regions is AstraZeneca pursuing approvals for Klygefa?

Klygefa is already approved in Japan and other countries for certain adults with gMG, and regulatory submissions based on PREVAIL are under review in the US, China and additional countries, indicating a broader global regulatory strategy.

AI-generated analysis. How Rhea-AI works. Not financial advice.

Form 6-K: How Foreign Companies Report to the SEC →

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Available on EDGAR 09/21/2026 - 07:04 AM Accepted by SEC EDGAR 09/21/2026 - 07:04 AM Learn about SEC filing dates

FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Issuer

Pursuant to Rule 13a-16 or 15d-16 of

the Securities Exchange Act of 1934

For the month of September 2026 

Commission File Number: 001-11960

AstraZeneca PLC

1 Francis Crick Avenue

Cambridge Biomedical Campus

Cambridge CB2 0AA

United Kingdom

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F X Form 40-F __

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ______

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes __ No X

If “Yes” is marked, indicate below the file number assigned to the Registrant in connection with Rule 12g3-2(b): 82-_____________

AstraZeneca PLC

INDEX TO EXHIBITS

1.

Klygefa recommended for EU approval by CHMP

21 September 2026

Klygefa (gefurulimab) recommended for approval in the EU by CHMP for the treatment of adults with generalised myasthenia gravis (gMG)

Recommendation based on PREVAIL Phase III trial demonstrating statistically significant and clinically meaningful improvement in Myasthenia Gravis Activities of Daily Living score

If approved, Klygefa will be the first and only dual-binding nanobody C5 inhibitor for gMG in the EU, offering once weekly subcutaneous self-administration with rapid and sustained symptom control

Alexion, AstraZeneca Rare Disease's Klygefa (gefurulimab) has been recommended for approval in the European Union (EU) as an add-on to standard therapy for the treatment of generalised myasthenia gravis (gMG) in adults who are anti-acetylcholine receptor (AChR) antibody-positive. If approved, Klygefa will be the first and only dual-binding nanobody C5 inhibitor for this patient population. 

The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) based its positive opinion on results from the pivotal PREVAIL Phase III trial, which were presented at the Myasthenia Gravis Foundation of America (MGFA) Scientific Session during the American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) 2025 Annual Meeting and published in JAMA Neurology.1

gMG is a rare autoimmune disorder characterised by reduced muscle function and severe muscle weakness.2 An estimated 82,500 people are diagnosed with gMG in Europe 5 countries (Germany, France, UK, Italy and Spain) with 66,000 being AChR-positive.3

Tobias Ruck, MD, Director Department of Neurology, BG University Hospital Bergmannsheil Bochum, Ruhr-University Bochum and investigator in the trial, said: "For people living with gMG, unpredictable symptoms can quickly become incapacitating or life-threatening. In the PREVAIL Phase III trial, gefurulimab demonstrated the ability to improve measures of disease severity and daily function with the convenience of once weekly subcutaneous self-administration, as early as one week and through the 26-week study period. With this positive CHMP opinion patients may soon have the option of a novel treatment option that could help them spend less time thinking about their care and more time living their lives."

Marc Dunoyer, Chief Executive Officer, Alexion, said: "This positive CHMP opinion is an important step towards bringing Klygefa, an innovative dual-binding nanobody C5 inhibitor, to people living with gMG in the EU. Building on our pioneering work demonstrating the efficacy of C5 inhibition with Soliris and Ultomiris, Klygefa is designed to offer rapid and sustained symptom control with convenient once-weekly subcutaneous self-administration via autoinjector."

Results from the PREVAIL trial showed that Klygefa met its primary endpoint, demonstrating improvement from baseline in Myasthenia Gravis Activities of Daily Living (MG-ADL) total score at week 26 compared to placebo (treatment difference: -1.6 [95% CI: -2.4, -0.8], p<0.0001). A clinically meaningful improvement was observed as early as week one, and was sustained through week 26.1

Klygefa was generally well-tolerated, and the safety profile was consistent with previous trials of C5 inhibitors eculizumab and ravulizumab in gMG.1

Klygefa is approved in Japan and other countries for certain adults with gMG. Regulatory submissions based on the PREVAIL results are under review in the US, China and additional countries.

Notes

Generalised Myasthenia Gravis (gMG)

Generalised myasthenia gravis (gMG) is a rare autoimmune disorder characterised by reduced muscle function and severe muscle weakness.2

Eighty-five percent of people with gMG are AChR antibody-positive meaning they produce specific antibodies (anti-AChR) that bind to signal receptors at the neuromuscular junction (NMJ), the connection point between nerve cells and the muscles they control.4 This binding activates the complement system, causing the immune system to attack the NMJ, leading to inflammation and a breakdown in communication between the brain and the muscles.5

gMG can occur at any age, but it most commonly begins for women before the age of 40 and for men after the age of 60.6 Initial symptoms may include slurred speech, double vision, droopy eyelids and lack of balance; these can often lead to more severe symptoms as the disease progresses, such as impaired swallowing, choking, extreme fatigue and respiratory failure.7,8

PREVAIL (ALXN1720-MG-301)

PREVAIL (ALXN1720-MG-301) is a global, Phase III, randomised, double-blind, placebo-controlled, parallel, multicentre study evaluating the safety and efficacy of Klygefa in adults with generalised myasthenia gravis (gMG). The trial enrolled 260 patients from 20 countries across North America, Europe, Asia and the Pacific region. Participants were required to have a confirmed myasthenia gravis diagnosis at least three months prior to the screening visit with a positive serological test for autoantibodies against AChR and Myasthenia Gravis Foundation of America Clinical Classification Class II to IV at screening.9

Patients were randomised 1:1 to receive Klygefa or placebo for a total of 26 weeks in the randomised controlled treatment period. Patients received a single weight-based loading dose on Day 1, followed by regular weight-based maintenance dosing beginning on Day 8 and once every week thereafter. The primary endpoint of the change from baseline in the Myasthenia Gravis Activities of Daily Living (MG-ADL) total score, a patient-reported scale that assesses patients' abilities to perform daily activities, was assessed at week 26 along with multiple secondary endpoints evaluating improvement in disease-related measures.9

Patients who completed the randomised controlled treatment period were eligible to continue into an open-label extension period evaluating the safety and efficacy of Klygefa, which is ongoing.9

Klygefa (gefurulimab)

Klygefa (gefurulimab), a complement C5 inhibitor, is a novel dual-binding nanobody optimised for subcutaneous self-administration in development as a treatment for AChR-Ab+ gMG. The medication works by binding to the C5 protein in the terminal complement cascade, a part of the body's immune system. When activated in an uncontrolled manner, the complement cascade over-responds, leading the body to attack its own healthy cells. Klygefa's concurrent binding to serum albumin provides an extended half-life, enabling once-weekly dosing. 

Klygefa is approved in Japan and other countries for certain adults with gMG. Regulatory submissions based on the PREVAIL results are under review in the US, China and additional countries.

Alexion

Alexion, AstraZeneca Rare Disease, is focused on serving patients and families affected by rare diseases and devastating conditions through the discovery, development and delivery of life-changing medicines. A pioneering leader in rare disease for more than three decades, Alexion was the first to translate the complex biology of the complement system into transformative medicines, and today it continues to build a diversified pipeline across disease areas with significant unmet need, using an array of innovative modalities. As part of AstraZeneca, Alexion is continually expanding its global geographic footprint to serve more rare disease patients around the world. It is headquartered in Boston, US.

AstraZeneca

AstraZeneca (LSE/STO/NYSE: AZN) is a global, science-led biopharmaceutical company that focuses on the discovery, development, and commercialisation of prescription medicines in Oncology, Rare Disease, and BioPharmaceuticals, including Cardiovascular, Renal & Metabolism, and Respiratory & Immunology. Based in Cambridge, UK, AstraZeneca's innovative medicines are sold in more than 125 countries and used by millions of patients worldwide. Please visit astrazeneca.com and follow the Company on Social Media @AstraZeneca.

Contacts

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References

1.   Gwathmey KG, Saccà F, Howard JF Jr, et al. Efficacy and safety of gefurulimab in generalized myasthenia gravis: the PREVAIL phase 3 randomized clinical trial. JAMA Neurol. 2026 Jul 27.

2.    Jung-Plath W, et al. Assessment of myasthenia gravis patients' quality of life. The Journal of Neurosurgical Nursing. 2023;12(2):74-83.

3.    AstraZeneca Data on File - Epidemiology estimates are composed of a triangulation of different data sources including Data Monitor, Decision Resources Group, Kantar Health, and internal input. Available here. Accessed September 2026.

4.   Lazaridis K, et al. Myasthenia gravis: autoantibody specificities and their role in MG management. Front Neurol. 2020;11:596981.

5.   Huang YF, et al. Visualization and characterization of complement activation in acetylcholine receptor antibody seropositive myasthenia gravis. Muscle Nerve. 2024.

6.   Cavanagh N, et al. Exploring the impairments and allied health professional utilization in people with myasthenia gravis: a cross-sectional study. J Clin Neurosci. 2023;114:9-16.

7.   Catalin J, et al. Clinical presentation of myasthenia gravis. Thymus. 2019.

8.   Farid ZR, et al. Factors affecting generalization of ocular myasthenia gravis. Sriwijaya Journal of Ophthalmology. 2020;3(2):48-54.

9.   ClinicalTrials.gov. Safety and efficacy of ALXN1720 in adults with generalized myasthenia gravis. NCT Identifier: NCT05556096. Available here. Accessed September 2026.

Matthew Bowden

Company Secretary

AstraZeneca PLC

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

AstraZeneca PLC

Date: 21 September 2026

By: /s/ Matthew Bowden

Name: Matthew Bowden

Title: Company Secretary