TLDR
- JNJ jumps 3.52% as IMAAVY data strengthens its gMG treatment case.
- IMAAVY showed stronger symptom control in early-stage gMG patients.
- New data showed benefits in patients with lower baseline symptom burden.
- Patients on IMAAVY maintained control after common infection periods.
- Johnson & Johnson adds pregnancy safety tracking through PETUNIA study.
Johnson & Johnson shares rose 3.52% to $253.49 after new IMAAVY findings strengthened its profile in generalized myasthenia gravis. The stock surged after the opening bell before consolidating near its intraday highs during early afternoon trading. The company reported findings on earlier treatment, symptom control, infections, safety, and pregnancy monitoring.
IMAAVY Data Support Earlier gMG Treatment
Johnson & Johnson presented 12 IMAAVY abstracts at the European Academy of Neurology 2026 Congress. The research covered several clinically relevant stages within the generalized myasthenia gravis treatment journey. It included adults with anti-AChR or anti-MuSK antibody-positive forms of the disease.
One analysis examined patients who received a gMG diagnosis within the previous five years. IMAAVY plus standard care reduced MG-ADL scores by 4.9 points after 24 weeks.Placebo plus standard care reduced the scores by 2.7 points.
 More IMAAVY patients achieved meaningful clinical improvement for at least 20 weeks. The measure required patients to record an MG-ADL improvement of at least two points. The findings supported sustained symptom control during the double-blind phase of Vivacity-MG3.
Lower Symptom Burden and Infection Findings
Another analysis assessed patients who entered the study with MG-ADL scores below nine. IMAAVY reduced their scores by 4.5 points, while placebo produced a 2.3-point reduction. The treatment also delivered larger QMG improvements, which measure muscle weakness and disease severity.
Researchers also studied patients who developed common infections during the Vivacity-MG3 trial. Infections can trigger symptom deterioration and increase the risk of serious gMG complications. IMAAVY patients maintained their symptom improvements within two weeks after infection.
Infection rates remained similar between both study groups during the trial. Infections affected 42.9% of IMAAVY patients and 41.8% of placebo patients. The findings provided further information about symptom control during periods of increased disease risk.
Safety Results and Pregnancy Research
Overall adverse events affected 84% of patients in both treatment groups. Serious adverse events affected 9% of IMAAVY patients and 14% of placebo patients. Johnson & Johnson reported consistent safety results across Vivacity-MG3 and other nipocalimab studies.
IMAAVY can increase infection risks, including the possibility of serious infections. Healthcare professionals should delay treatment for patients with active infections until those infections resolve. Common side effects include respiratory infections, peripheral swelling, and muscle spasms.
Johnson & Johnson also outlined PETUNIA, a post-marketing pregnancy safety study. The study will track pregnancy, maternal, and infant outcomes following IMAAVY exposure. Researchers will use prospective and retrospective reports to expand the limited evidence covering treatment during pregnancy.
IMAAVY Targets Harmful IgG Antibodies
Generalized myasthenia gravis causes antibodies to disrupt communication between nerves and muscles. Patients can experience muscle weakness and difficulties with speaking, swallowing, and normal movement. The disease affects an estimated 700,000 people worldwide across different ages and populations.
The Vivacity-MG3 trial enrolled 199 adults whose symptoms remained uncontrolled under standard treatment. Researchers assigned participants to receive either IMAAVY or placebo alongside their existing care. The primary endpoint measured changes in daily activity scores through weeks 22, 23, and 24.
IMAAVY blocks the neonatal Fc receptor and reduces harmful circulating IgG antibodies.The treatment preserves other important parts of the body’s immune function. American and European regulators approve it for eligible patients aged 12 years and older with antibody-positive gMG.
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