Regeneron Announces Positive Results from Phase 3 Trial in Generalized Myasthenia Gravis

Cemdisiran monotherapy, dosed subcutaneously every three months, met the primary and key secondary endpoints, showing a 2.3-point placebo-adjusted improvement in Myasthenia Gravis Activities of Daily Living (MG-ADL) total score

U.S. regulatory submission for cemdisiran monotherapy is planned for the first quarter of 2026, pending discussions with the FDA

TARRYTOWN, N.Y., Aug. 26, 2025 (GLOBE NEWSWIRE) -- Regeneron Pharmaceuticals, Inc. (NASDAQ:REGN) today announced that the primary and key secondary endpoints were met in the Phase 3 NIMBLE trial assessing investigational cemdisiran monotherapy in adults with generalized myasthenia gravis (gMG). Cemdisiran is an siRNA that reduces circulating levels of complement factor 5 (C5) and, as monotherapy in this trial, was associated with an average of 74% inhibition of complement activity. The trial also assessed a combination of cemdisiran and pozelimab, a C5 antibody; this combination ("cemdi-poze"), which resulted in nearly 99% inhibition of complement activity, also met the primary and key secondary endpoints, though cemdisiran monotherapy was numerically better across these endpoints.

"Our pipeline approach to treating complement-mediated diseases allows us to tailor treatment to the underlying disease biology," said L. Andres Sirulnik, M.D., Ph.D., Senior Vice President and Hematology Clinical Development Unit Head at Regeneron. "The results of the NIMBLE trial confirm that, in myasthenia gravis, robust efficacy can be achieved without complete complement blockade, whereas in other diseases such as paroxysmal nocturnal hemoglobinuria (PNH), complete inhibition is likely to be necessary. We have previously released data from the lead-in portion of our PNH Phase 3 trial, supporting the potential for the cemdi-poze combination to deliver best-in-class efficacy in PNH. We are also investigating systemic administration of both cemdisiran monotherapy and the cemdi-poze combination in our Phase 3 program for geographic atrophy secondary to age-related macular degeneration."

"The NIMBLE trial results underscore the potential for cemdisiran to offer a best-in-class profile for those suffering with myasthenia gravis, providing for robust efficacy with a convenient quarterly subcutaneous administration," said George D. Yancopoulos, M.D., Ph.D., Board co-Chair, President and Chief Scientific Officer at Regeneron. "The potential for best-in-class efficacy with less than complete complement blockade with cemdisiran monotherapy may also provide for a more favorable safety profile. These exciting results highlight the transformative potential of our siRNA and genetic medicines pipeline to deliver paradigm-changing therapies for patients."

The NIMBLE trial evaluated adults with symptomatic gMG who have antibodies to the acetylcholine receptor (anti-AChR) and may be receiving standard of care immunosuppressants based on the investigator's discretion. Patients were randomized to receive subcutaneous administrations of: cemdisiran (600 mg) every 12 weeks, cemdi-poze (cemdisiran 200 mg and pozelimab 200 mg) every 4 weeks, or placebo every 4 weeks. The primary endpoint assessed total score changes from baseline to week 24 in the Myasthenia Gravis Activities of Daily Living (MG-ADL) total score, a patient-reported questionnaire that measures daily functions impacted by gMG, such as talking, eating, breathing, vision and mobility. The key secondary endpoint assessed total score changes from baseline in the Quantitative Myasthenia Gravis (QMG) total score, a physician-administered assessment evaluating vision, speaking/swallowing, breathing and limb function.

Historical clinical trial data report that currently approved C5 inhibitor therapies have shown a placebo-adjusted treatment difference in MG-ADL total scores ranging from ­-1.6 to -2.1 at 12 to 26 weeks.

Both cemdisiran and cemdi-poze demonstrated improvements in activities of daily functioning at week 24, with cemdisiran showing numerically better results across all gMG-specific outcomes. In the MG-ADL and QMG, greater reductions in total scores indicate greater improvement in disease symptoms and better treatment effect.

	cemdisiran (n=64)	cemdi-poze (n=67)	placebo (n=59)
Patients completing trial treatment	100%	96%	90%
Primary endpoint: Change from baseline in MG-ADL total score
Placebo-adjusted treatment difference	-2.30 (p=0.0005)	-1.74 (p=0.0086)
Mean change from baseline†	-4.52	-3.96	-2.22
Key secondary endpoint: Change from baseline in QMG total score
Placebo-adjusted treatment difference	-2.77 (p=0.0015)	-1.86 (p=0.0348)
Mean change from baseline†	-4.24	-3.32	-1.46
Other secondary endpoints
MG-ADL: Patients achieving ≥3-point reduction	76.6% Relative risk: 1.84 (p=0.0001)†	65.7% Relative risk: 1.51 (p=0.0135)†	44.1%
QMG: Patients achieving ≥5-point reduction	48.4% Relative risk: 2.67 (p=0.0006)†	35.8% Relative risk: 1.93 (p=0.0367)†	19%

^†Means and relative risks were adjusted per the amount immunosuppressant treatment and the Myasthenia Gravis Foundation of America Clinical Classification determined at screening. Means were also adjusted for baseline MG-ADL or QMG score.

There were no meningococcal infections in any patient. There were no treatment discontinuations due to adverse events through week 24 in the cemdisiran arm.

Across all arms, treatment-emergent adverse events (TEAEs) occurred in 69% of patients treated with cemdisiran, 81% with cemdi-poze, and 77% with placebo. Serious TEAEs occurred in 3% of patients treated with cemdisiran, 9% with cemdi-poze and 14% with placebo. The most common TEAEs observed in ≥5% of patients receiving cemdisiran, cemdi-poze or placebo were: worsening of MG (1%, 5%, 17%), upper respiratory tract infection (12%, 8%, 11%), urinary tract infection (5%, 6%, 3%), nasopharyngitis (5%, 3%, 4%), headache (5%, 11%, 10%), rash (5%, 3%, 1%), injection site reaction (4%, 8%, 1%), diarrhea (3%, 14%, 7%), arthralgia (1%, 6%, 1%), pain in extremity (1%, 5%, 1%), cough (1%, 5%, 1%), and pruritus (0%, 5%, 0%). There were no deaths during the 24-week placebo-controlled portion of the trial. During the extension period, one death due to pneumonia occurred in the cemdisiran arm, and one death due to septic shock occurred in the combination arm; both deaths occurred in patients who were on concomitant immuno-suppressive therapies.

Detailed results from the NIMBLE trial will be presented at an upcoming medical meeting. The U.S. regulatory application for cemdisiran is planned for the first quarter of 2026, pending discussions with the FDA.

The potential use of cemdisiran and/or pozelimab for the treatment of gMG is investigational and has not been approved by any regulatory authority. In the U.S., pozelimab monotherapy is approved as Veopoz^® (pozelimab-bbfg) for adult and pediatric patients 1 year of age and older with CHAPLE disease, also known as CD55-deficient protein-losing enteropathy, which includes a Boxed Warning for life-threatening and fatal meningococcal infections.

About Myasthenia Gravis (MG)

MG is a rare and chronic autoimmune disease where abnormal antibodies activate the complement system including C5, disrupting communication between nerves and muscles that results in debilitating and potentially life-threatening muscle weakness. In the U.S., the disease impacts approximately 85,000 people. Initial manifestations are usually ocular, but approximately 85% of MG patients experience additional advancements to the disease manifestations, which is known as generalized myasthenia gravis (gMG). For these patients, the disease affects muscles throughout the body, resulting in extreme fatigue and difficulties with facial expression, speech, swallowing and mobility. Treatment-related challenges – which include frequent hospital visits, inconsistent symptom control, and lack of durable treatment effects – can further affect quality of life and long-term disease management.

About the Complement Factor 5 (C5) Clinical Program

NIMBLE is a randomized, double-blind, placebo-controlled trial evaluating cemdisiran and cemdi-poze in patients with gMG who have antibodies for AChR. The primary endpoint assessed changes in the MG-ADL total score from baseline to week 24. The MG-ADL scale is an eight-question patient-reported tool that measures how gMG affects aspects of daily life and provides a total score ranging from 0 to 24. The key secondary endpoint was the change from baseline in QMG total score at week 24. The QMG is a physician-administered 13-item standardized assessment evaluating muscle function that provides a total score ranging from 0 to 39. In both MG-ADL and QMG, a higher total score indicates greater disease severity, and a larger reduction in total score indicates greater improvement in disease symptoms and better treatment effect.

Cemdisiran and pozelimab are also being evaluated in separate Phase 3 trials as both monotherapy and combination therapy for additional complement-mediated disorders, including PNH and geographic atrophy secondary to age-related macular degeneration. For more information, visit the Regeneron clinical trials website, or contact [email protected] or +1 844-734-6643.

Cemdisiran as a monotherapy and in combination with pozelimab was being developed under an initial agreement with Alnylam Pharmaceuticals, Inc. In June 2024, Regeneron and Alnylam entered into an amended and restated C5 License Agreement, which granted Regeneron a worldwide license to cemdisiran as a monotherapy in addition to a license to cemdisiran in combination with C5 antibodies. Regeneron is solely responsible for development, manufacturing, and commercialization of cemdisiran as a monotherapy and in combination with C5 antibodies. For cemdisiran as a monotherapy, Alnylam is entitled to receive certain regulatory milestone payments as well as tiered, double-digit royalties (up to 15%) on calendar-year net sales. If cemdisiran is used as part of a combination product, Alnylam is entitled to receive a flat, low double-digit royalty on calendar-year net sales as well as commercial milestones of up to $325.0 million.

IMPORTANT SAFETY INFORMATION

What is the most important information I should know about VEOPOZ?

VEOPOZ is a medicine that affects your immune system and can lower the ability of your immune system to fight infections.

• VEOPOZ increases your chance of getting serious and life-threatening meningococcal infections that may quickly become life-threatening and cause death if not recognized and treated early.
  
  
  
  

1. You must receive meningococcal vaccines at least 2 weeks before your first dose of VEOPOZ if you have not already had these vaccines.
   
   
2. If you had a meningococcal vaccine in the past, you might need additional vaccination before starting VEOPOZ. Your healthcare provider will decide if you need additional meningococcal vaccination.
3. If your healthcare provider decides that urgent treatment with VEOPOZ is needed, and your meningococcal vaccines are not up-to-date, you should receive meningococcal vaccination as soon as possible. You should also receive antibiotics.
4. Meningococcal vaccines reduce the risk of meningococcal infection but do not prevent all meningococcal infections. Call your healthcare provider or get emergency medical care right away if you get any of these signs and symptoms of a meningococcal infection:
   • headache with nausea or vomiting
   • headache with a stiff neck or stiff back
   • fever and a rash
   • muscle aches with flu-like symptoms
   • headache and fever
   • fever
   • confusion
   • eyes sensitive to light

Your healthcare provider will give you a Patient Safety Card about the symptoms of meningococcal, or other infection. Carry it with you at all times during treatment and for 3 months after your last VEOPOZ dose. Your risk of meningococcal infection may continue for several weeks after your last dose of VEOPOZ. It is important to show this card to any healthcare provider who treats you. This will help them diagnose and treat you quickly.

VEOPOZ may also increase the risk of other types of serious bacterial infections.

• People who take VEOPOZ may have an increased risk of getting infections caused by Streptococcus pneumoniae and Haemophilus influenzae.
• Certain people may also have an increased risk of bacterial infection including gonorrhea infection. Talk to your healthcare provider to find out if you are at risk of gonorrhea infection, about gonorrhea prevention, and regular testing.

Call your healthcare provider right away if you have any new signs or symptoms of infection.

Do not receive VEOPOZ if you have a meningococcal infection.

Before you receive VEOPOZ, tell your healthcare provider about all of your medical conditions, including if you: have an infection or fever, are pregnant or plan to become pregnant, and are breastfeeding or plan to breastfeed. It is not known if VEOPOZ will harm your unborn baby or if it passes into your breast milk. Talk to your healthcare provider about the best way to feed your baby during treatment with VEOPOZ.

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. It is important that you have all recommended vaccinations before you start VEOPOZ, receive antibiotics if you start VEOPOZ within 2 weeks of receiving meningococcal vaccination, and stay up to date with all recommended vaccinations during treatment with VEOPOZ.

VEOPOZ and other medicines may affect each other, causing side effects. VEOPOZ may affect the way other medicines work, and other medicines may affect how VEOPOZ works.



Especially tell your healthcare provider if you take Intravenous Immunoglobulin (IVIg).

Know the medicines you take and the vaccines you receive. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.

What are the possible side effects of VEOPOZ?

VEOPOZ can cause serious side effects including allergic (hypersensitivity) reactions including infusion-related reactions, which may happen during your treatment. Tell your healthcare provider right away if you develop any of these symptoms or any other symptom during your VEOPOZ treatment that may mean you are having a serious allergic reaction: chest pain, trouble breathing or shortness of breath, swelling of your face, tongue, or throat, and feel faint or pass out.

The most common side effects of VEOPOZ are upper respiratory tract infection, fracture, raised, red patches of skin that are often very itchy (hives), and hair loss (alopecia).

Tell your healthcare provider if you have any side effect that bothers you or that does not go away. These are not all of the possible side effects of VEOPOZ. Call your healthcare provider for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Please see the full Prescribing Information, including Boxed WARNING, and Medication Guide for VEOPOZ.

About Regeneron's VelocImmune^® Technology

Regeneron's VelocImmune technology utilizes a proprietary genetically engineered mouse platform endowed with a genetically humanized immune system to produce optimized fully human antibodies. When Regeneron's co-Founder, President and Chief Scientific Officer George D. Yancopoulos was a graduate student with his mentor Frederick W. Alt in 1985, they were the first to envision making such a genetically humanized mouse, and Regeneron has spent decades inventing and developing VelocImmune and related VelociSuite^® technologies. Dr. Yancopoulos and his team have used VelocImmune technology to create a substantial proportion of all original, FDA-approved or authorized fully human monoclonal antibodies. This includes REGEN-COV^® (casirivimab and imdevimab), Dupixent^® (dupilumab), Libtayo^® (cemiplimab-rwlc), Praluent^® (alirocumab), Kevzara^® (sarilumab), Evkeeza^® (evinacumab-dgnb), Inmazeb^® (atoltivimab, maftivimab and odesivimab-ebgn) and Veopoz^® (pozelimab).

About Regeneron

Regeneron (NASDAQ:REGN) is a leading biotechnology company that invents, develops and commercializes life-transforming medicines for people with serious diseases. Founded and led by physician-scientists, our unique ability to repeatedly and consistently translate science into medicine has led to numerous approved treatments and product candidates in development, most of which were homegrown in our laboratories. Our medicines and pipeline are designed to help patients with eye diseases, allergic and inflammatory diseases, cancer, cardiovascular and metabolic diseases, neurological diseases, hematologic conditions, infectious diseases, and rare diseases.

Regeneron pushes the boundaries of scientific discovery and accelerates drug development using our proprietary technologies, such as VelociSuite, which produces optimized fully human antibodies and new classes of bispecific antibodies. We are shaping the next frontier of medicine with data-powered insights from the Regeneron Genetics Center^® and pioneering genetic medicine platforms, enabling us to identify innovative targets and complementary approaches to potentially treat or cure diseases.

For more information, please visit www.Regeneron.com or follow Regeneron on LinkedIn, Instagram, Facebook or X.

Forward-Looking Statements and Use of Digital Media

This press release includes forward-looking statements that involve risks and uncertainties relating to future events and the future performance of Regeneron Pharmaceuticals, Inc. ("Regeneron" or the "Company"), and actual events or results may differ materially from these forward-looking statements. Words such as "anticipate," "expect," "intend," "plan," "believe," "seek," "estimate," variations of such words, and similar expressions are intended to identify such forward-looking statements, although not all forward-looking statements contain these identifying words. These statements concern, and these risks and uncertainties include, among others, the nature, timing, and possible success and therapeutic applications of products marketed or otherwise commercialized by Regeneron and/or its collaborators or licensees (collectively, "Regeneron's Products") and product candidates being developed by Regeneron and/or its collaborators or licensees (collectively, "Regeneron's Product Candidates") and research and clinical programs now underway or planned, including without limitation cemdisiran (an investigational siRNA therapeutic targeting C5) as a monotherapy and in combination with pozelimab (a fully human monoclonal antibody designed to block the activity of C5) (collectively, "Regeneron's C5 Product Candidates"); the likelihood, timing, and scope of possible regulatory approval and commercial launch of Regeneron's Product Candidates and new indications for Regeneron's Products, such as any of Regeneron's C5 Product Candidates for the treatment of generalized myasthenia gravis as discussed in this press release as well as other complement-mediated conditions (including paroxysmal nocturnal hemoglobinuria and/or geographic atrophy); uncertainty of the utilization, market acceptance, and commercial success of Regeneron's Products and Regeneron's Product Candidates and the impact of studies (whether conducted by Regeneron or others and whether mandated or voluntary), including the studies discussed or referenced in this press release, on any of the foregoing or any potential regulatory approval of Regeneron's Products and Regeneron's Product Candidates (such as Regeneron's C5 Product Candidates); the ability of Regeneron's collaborators, licensees, suppliers, or other third parties (as applicable) to perform manufacturing, filling, finishing, packaging, labeling, distribution, and other steps related to Regeneron's Products and Regeneron's Product Candidates; the ability of Regeneron to manage supply chains for multiple products and product candidates and risks associated with tariffs and other trade restrictions; safety issues resulting from the administration of Regeneron's Products and Regeneron's Product Candidates (such as Regeneron's C5 Product Candidates) in patients, including serious complications or side effects in connection with the use of Regeneron's Products and Regeneron's Product Candidates in clinical trials; 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the extent to which the results from the research and development programs conducted by Regeneron and/or its collaborators or licensees may be replicated in other studies and/or lead to advancement of product candidates to clinical trials, therapeutic applications, or regulatory approval; unanticipated expenses; the costs of developing, producing, and selling products; the ability of Regeneron to meet any of its financial projections or guidance and changes to the assumptions underlying those projections or guidance; the potential for any license, collaboration, or supply agreement, including Regeneron's agreements with Sanofi and Bayer (or their respective affiliated companies, as applicable) and the agreement with Alnylam Pharmaceuticals, Inc. referenced in this press release, to be cancelled or terminated; the impact of public health outbreaks, epidemics, or pandemics on Regeneron's business; and risks associated with litigation and other proceedings and government investigations relating to the Company and/or its operations (including the pending civil proceedings initiated or joined by the U.S. Department of Justice and the U.S. Attorney's Office for the District of Massachusetts), risks associated with intellectual property of other parties and pending or future litigation relating thereto (including without limitation the patent litigation and other related proceedings relating to EYLEA^® (aflibercept) Injection), the ultimate outcome of any such proceedings and investigations, and the impact any of the foregoing may have on Regeneron's business, prospects, operating results, and financial condition. 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