In late October 2025, Johnson & Johnson announced long-term data from the Vibrance-MG Phase 2/3 LTE pediatric study, which showed nipocalimab-aahu (IMAAVY) plus standard of care produced sustained clinical benefits in pediatric patients aged 12 and older with generalized myasthenia gravis (gMG). The monoclonal antibody is designed to bind with high affinity to block FcRn and reduce levels of circulating immunoglobulin G (IgG) antibodies that underlie gMG without additional detectable effects on other adaptive and innate immune functions, as described by Johnson & Johnson.
The treatment led to durable IgG reductions through 72 weeks, including a median ~73% reduction by Week 24, along with continued improvements in daily function and muscle strength. Safety findings remained consistent with earlier results, with no new concerns identified during extended follow-up.
The outcomes align with results from the adult Vivacity-MG3 study and its open-label extension, underscoring a differentiated treatment profile across major antibody subtypes (AChR+ and MuSK+).
"Pediatric patients with gMG have long been an underserved population in neuromuscular disease research,” said Jonathan Strober, MD, director, Pediatric Neuromuscular Program; professor of Pediatrics and Neurology, University of California at San Francisco, at the time of data announcement. "These new Vibrance-MG LTE pediatric data are especially encouraging, showing treatment with nipocalimab-aahu achieved sustained meaningful improvements in daily function and muscle strength, echoing the results seen in the Vivacity-MG3 OLE study in adults. These data represent an important potential advance in the care of pediatric patients, offering hope for lasting disease control.”
The monoclonal antibody is approved by the FDA for adult and pediatric patients 12 years and older with anti-AChR or anti-MuSK antibody-positive gMG.
Below, Contemporary Pediatrics presents a written Q&A with Jonathan Strober, MD, who offers a deeper clinical context on the Vibrance-MG Pediatric Phase 2/3 Study.
Contemporary Pediatrics:
Can you explain the background, number of participants, and objectives of the Vibrance-MG Pediatric P2/3 Study, and provide some background on generalized myasthenia gravis, for our audience of general pediatricians?
Strober:
The objective of the study is to evaluate the effect of nipocalimab on pharmacodynamics (IgG), safety, and efficacy in adolescents aged 12 to <18 years with gMG who exhibit an insufficient clinical response to SOC therapy. Eight patients were included in this data set.
Generalized myasthenia gravis (MG) in adolescents, also termed juvenile myasthenia gravis (JMG) when onset is before age 18, is a rare autoimmune disorder characterized by fluctuating, fatigable weakness affecting multiple muscle groups, including eyes, face and mouth, limb, and respiratory muscles. Facial and respiratory involvement can lead to life-threatening myasthenic crisis. First-line treatment includes acetylcholinesterase inhibitors (e.g., pyridostigmine), with early introduction of immunosuppression (prednisone, steroid-sparing agents) if symptoms are not controlled.
Contemporary Pediatrics:
What observations were made, and what were the primary outcomes?
Strober:
Nipocalimab treatment resulted in a rapid and sustained IgG reduction in adolescent participants with gMG, similar to that seen in adults. A clinically meaningful reduction in MG-ADL score (functional data) was observed by Week 4 and was maintained through both active treatment and long-term extension phases.
Contemporary Pediatrics:
How important is the sustained data among this pediatric population, noting they were reported as consistent with the ongoing OLE in adults?
Strober:
It is very important to know that this treatment can be given safely and effectively over years to help our adolescent patients maintain a positive quality of life.
Contemporary Pediatrics:
What should the general provider know about these data?
Strober:
This data allowed for the FDA approval of this drug in children 12 years and older. The first approval for a drug of this kind and only the second approved drug for this condition in this age group.
Contemporary Pediatrics:
Is there anything else you would like to include?
Strober:
MG can affect children, and we are excited to expand our ability to treat this disease safely and effectively.
Editor's note: Jonathan Strober, MD, has disclosures with Scholar Rock, Argenx, Johnson & Johnson, Biogen, PTC, Biohaven, Alexion, Laramir.
Strober is a paid editor, associate editor, or editorial advisory board member for Pediatric Neurology.
Strober discloses expert witness fees from many law firms.
Reference:
Johnson & Johnson announces first head-to-head study comparing IMAAVY™ with an alternative FcRn blocker in generalized myasthenia gravis (gMG) at AANEM Annual Meeting. Johnson & Johnson. Press release. October 29, 2025. Accessed November 26, 2025. https://www.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
