Long-term Safety of Efgartigimod for Myasthenia Gravis

(ADAPT Jr + Trial)

Enrolling by invitation at 50 trial locations

Overseen By Sabine s Coppieters, MD

Age: < 65

Sex: Any

Trial Phase: Phase 2 & 3

Sponsor: argenx

Disqualifiers: Pregnancy, Lactation, Autoimmune disease, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Prior Safety Data This treatment has passed at least one previous human trial

Approved in 2 Jurisdictions This treatment is already approved in other countries

Compensation: Varies

Number of Visits: Unknown

Duration: Long-term

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests the long-term safety of efgartigimod, an immunotherapy for individuals with generalized myasthenia gravis (gMG), a condition that causes muscle weakness. Participants will receive efgartigimod either through an IV or under the skin to assess its ongoing safety and effectiveness. The study is open to those who have already participated in specific previous studies related to this treatment. Individuals who completed those studies and are willing to adhere to the trial's guidelines may be suitable candidates. As a Phase 2, Phase 3 trial, this study evaluates the treatment's effectiveness in an initial group and represents the final step before FDA approval, offering participants a chance to contribute to a potentially groundbreaking therapy.

Do I need to stop my current medications to join the trial?

The trial information does not specify whether you need to stop taking your current medications. It's best to discuss this with the trial team or your doctor.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research has shown that efgartigimod, available in both IV (intravenous) and PH20 SC (under the skin) forms, is generally safe for individuals with generalized myasthenia gravis (gMG). Earlier studies identified respiratory infections, headaches, and urinary tract infections as the most common side effects, which are already associated with efgartigimod use.

For the IV form, no new safety issues have emerged with long-term use, though some studies mention potential kidney or metabolic problems over time. The under-the-skin form has also demonstrated long-term safety and consistent effectiveness in improving symptoms.

Both treatments are generally well-tolerated, but like any medication, they may pose some risk of side effects. Discussing potential risks and benefits with a healthcare professional before starting any new treatment is important. ^{1 2 3 4 5}

Why are researchers excited about this trial's treatments?

Efgartigimod is unique because it offers a novel approach to treating myasthenia gravis by targeting the neonatal Fc receptor (FcRn). Most current treatments for this condition, like acetylcholinesterase inhibitors, immunosuppressants, or corticosteroids, work by either increasing communication at the neuromuscular junction or broadly suppressing the immune system. Efgartigimod, on the other hand, specifically reduces pathogenic antibodies by interfering with FcRn, potentially leading to fewer side effects and a more targeted action. Researchers are excited about this treatment because it promises a more precise method of managing symptoms, which could result in better long-term outcomes for patients.

What evidence suggests that efgartigimod is effective for myasthenia gravis?

Research shows that efgartigimod, available in both IV (intravenous) and SC (subcutaneous) forms, holds promise for people with generalized Myasthenia Gravis (gMG). In this trial, participants will receive either Efgartigimod IV or Efgartigimod PH20 SC. Studies have found that patients experience significant improvements in their ability to perform daily activities, as measured by the MG-ADL scale, within just a few weeks of starting treatment. Additionally, long-term data up to 170 weeks indicate that efgartigimod remains effective over time. This treatment targets and reduces specific antibodies that contribute to gMG symptoms. Overall, these findings suggest that efgartigimod could effectively manage gMG. ^{1 6 7 8 9}

Are You a Good Fit for This Trial?

This trial is for children who have a muscle weakness condition called generalized myasthenia gravis and were part of an earlier study (ARGX-113-2006). They must not plan to donate sperm or become pregnant, agree to use contraception, and understand the trial's requirements. Those with hypersensitivity to efgartigimod, recent live vaccines, other autoimmune diseases, or uncontrolled infections cannot join.

Inclusion Criteria

Participants must have completed ARGX-113-2006 or ARGX-113-2207 and agreed to participate in the ARGX-113-2008 trial

I am a female of childbearing age and my pregnancy test before the trial was negative.

Participants who qualify for retreatment in trial ARGX-113-2006 but cannot complete the required visits within the trial's timeframe

Exclusion Criteria

Known hypersensitivity reaction to efgartigimod or any of its excipients

Early discontinuation from ARGX-113-2006 or ARGX-113-2207 treatment

I do not have an autoimmune disease or any condition that could affect my gMG symptoms or increase my risk.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants receive Efgartigimod IV or Efgartigimod PH20 SC treatment

Long-term

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Efgartigimod IV

Trial Overview

The trial is testing the long-term safety of a medication called Efgartigimod IV in children who previously participated in another related study. It aims to ensure that this treatment continues to be safe over an extended period.

How Is the Trial Designed?

Group I: Efgartigimod or Efgartigimod PH20 SC Experimental Treatment 1 Intervention

Patients receiving Efgartigimod IV treatment or Efgartigimod PH 20 SC treatment

Efgartigimod IV is already approved in United States, European Union for the following indications:

Approved in United States as Vyvgart for:

• Generalized myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) antibody positive

Approved in European Union as Vyvgart for:

• Generalized myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) antibody positive

Approved in United States as Vyvgart Hytrulo for:

• Generalized myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor (AChR) antibody positive
• Chronic inflammatory demyelinating polyneuropathy (CIDP)

Who Is Running the Clinical Trial?

argenx

Lead Sponsor

Trials

76

Recruited

11,500+

Tim Van Hauwermeiren

argenx

Chief Executive Officer since 2008

B.Sc. and M.Sc. in Bioengineering from Ghent University, Executive MBA from The Vlerick School of Management

Dr. Peter Ulrichts

argenx

Chief Medical Officer since 2023

MD from Maastricht University, PhD in Molecular Immunology from Maastricht University

Published Research Related to This Trial

Efgartigimod, a first-in-class neonatal Fc receptor antagonist, received its first approval in the USA in December 2021 for treating generalized myasthenia gravis in adults who are positive for anti-acetylcholine receptor antibodies.

The drug is also being evaluated for other autoimmune diseases and has been approved in Japan for generalized myasthenia gravis patients regardless of antibody status, indicating its potential broad application in autoimmune conditions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Efgartigimod: First Approval. Heo, YA.[2022]

Efgartigimod, a human IgG1 antibody, significantly improved symptoms in patients with generalized myasthenia gravis, with 68% of treated patients showing a meaningful response compared to only 30% in the placebo group, indicating strong efficacy.

The treatment was well tolerated, with similar rates of adverse events between efgartigimod and placebo groups, suggesting it is a safe option for patients, with no deaths reported during the trial.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Safety, efficacy, and tolerability of efgartigimod in patients with generalised myasthenia gravis (ADAPT): a multicentre, randomised, placebo-controlled, phase 3 trial. Howard, JF., Bril, V., Vu, T., et al.[2022]

Efgartigimod alfa is the first neonatal Fc receptor antagonist approved for treating generalized myasthenia gravis (gMG), showing significant and rapid improvements in muscle strength and quality of life in a phase 3 trial with a placebo group.

The treatment was generally well tolerated, with most side effects being mild to moderate, indicating a favorable safety profile for patients with gMG.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Efgartigimod Alfa in Generalised Myasthenia Gravis: A Profile of Its Use. Heo, YA.[2023]

Efgartigimod was found to be safe and well-tolerated in a phase 2 study involving 24 patients with generalized myasthenia gravis, with no serious adverse events reported.

The treatment led to a significant reduction in pathogenic IgG autoantibodies and resulted in a rapid and long-lasting improvement in disease symptoms for 75% of patients, suggesting its potential as an effective therapy for myasthenia gravis.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Randomized phase 2 study of FcRn antagonist efgartigimod in generalized myasthenia gravis. Howard, JF., Bril, V., Burns, TM., et al.[2020]

In a study of 37 patients with acetylcholine receptor antibody-positive generalized myasthenia gravis, 72% experienced a significant improvement in daily living activities after one cycle of efgartigimod, indicating its efficacy in managing symptoms.

Efgartigimod treatment resulted in a substantial reduction in IgG levels and was generally well-tolerated, with only mild side effects reported, although one patient had to discontinue due to a Clostridium difficile infection.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Safety and outcomes with efgartigimod use for acetylcholine receptor-positive generalized myasthenia gravis in clinical practice. Katyal, N., Halldorsdottir, K., Govindarajan, R., et al.[2023]

Citations

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argenx.com/news/2025/press-release-3176635

argenx Presents New Data at AANEM and MGFA ...

These positive results in MG-ADL score mean patients experienced significant improvements in one or a combination of their abilities in ...

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Argenx pulls back curtain on Vyvgart trial win as part of ...

The company additionally laid out results on Vyvgart in adolescents with gMG, unveiled long-term data out to nearly 170 weeks and presented on ...

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clinicaltrials.gov

clinicaltrials.gov/study/NCT06909214

NCT06909214 | A Study to Evaluate the Clinical Outcomes ...

A Study to Evaluate the Clinical Outcomes of Efgartigimod PH20 SC in Adults With New-onset Generalized Myasthenia Gravis (gMG) (ADAPT-EARLY) · Study Overview.

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jnj.com

jnj.com/media-center/press-releases/johnson-johnson-announces-first-head-to-head-study-comparing-imaavy-with-an-alternative-fcrn-blocker-in-generalized-myasthenia-gravis-gmg-at-aanem-annual-meeting

The EPIC study will evaluate treatment with IMAAVY ...

The EPIC study will evaluate treatment with IMAAVY™ versus efgartigimod in adults with gMG and will include a treatment-switch arm

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pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC6556100/

Randomized phase 2 study of FcRn antagonist efgartigimod in ...

Data are minimum point improvements on the outcome measures of the MG-ADL scale on days 29 and 36, which are the study days in the follow-up period where the ...

6.

pmc.ncbi.nlm.nih.gov

pmc.ncbi.nlm.nih.gov/articles/PMC12041031/

A real-world pharmacovigilance study of efgartigimod alfa ...

However, renal adverse effects or metabolic problems may occur in the long-term treatment of patients with myasthenia gravis, especially when ...

7.

vyvgarthcp.com

vyvgarthcp.com/gmg/safety

Safety - VYVGART Hytrulo

The most common adverse reactions for VYVGART-treated patients were respiratory tract infection, headache, and urinary tract infection.

8.

sciencedirect.com

sciencedirect.com/science/article/pii/S2950221724000485

Long-term use of efgartigimod alfa in treating a young adult ...

EFG-α may be effective not only for MG but also for SLE, maintaining low disease activity and antibody levels. Long-term use could reduce steroid requirement.

9.

neurologylive.com

neurologylive.com/view/evaluating-risk-clarifying-safety-data-behind-efgartigimod

Clarifying the Safety Data Behind Efgartigimod

Josh Bryson, PhD, head of Medical Affairs at Argenx, discussed the safety profile of efgartigimod in light of recent FAERS-based infection data.