The FDA approved nipocalimab (Imaavy) injection to treat adults and children ages 12 and older with generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor (AChR) or anti-muscle-specific kinase (MuSK) antibody positive, Johnson & Johnson announced Wednesday.
Nipocalimab is designed to block the immunoglobulin G (IgG) binding site on the neonatal Fc receptor (FcRn) to reduce serum levels of total IgG, including pathogenic IgG autoantibodies in gMG.
It is the first FcRn blocker approved for both adult and pediatric gMG patients with anti-AChR or anti-MuSK antibodies, Johnson & Johnson said.
The FDA’s decision was based on the phase III Vivacity-MG3 study and its ongoing open-label extension. The primary endpoint in Vivacity-MG3 was the change in Myasthenia Gravis Activities of Daily Living (MG-ADL) scores from baseline to the average over weeks 22, 23, and 24 in seropositive patients with gMG. The MG-ADL scale ranges from 0 to 24, with higher scores indicating more severe symptoms.
Nipocalimab plus standard of care showed a greater improvement in MG-ADL scores (-4.7 points) compared with placebo plus standard of care (-3.25 points), a difference of -1.45 points (SE 0.470, P=0.002). The study also met key secondary endpoints and showed a sustained reduction in autoantibody levels by up to 75% throughout a 24-week monitoring period.
Participants on nipocalimab maintained improvements out to 20 months of follow-up in the open-label extension study, Johnson & Johnson said.
In the ongoing phase II/III Vibrance-MG study of adolescent gMG patients, nipocalimab plus standard of care achieved sustained reductions in IgG and appeared to be safe. From baseline to week 24 of the active treatment phase, the mean percentage change in total serum IgG from baseline was -68.98% (95% CI -78.4 to -59.6%). The drug also met secondary endpoints, including improvement in MG-ADL scores.
The most common adverse reactions in gMG patients treated with nipocalimab were respiratory tract infections, peripheral edema, and muscle spasms. Prescribing information warns against administering the drug to people with active infections.
“We consistently hear from individuals living with myasthenia gravis who are hopeful for new treatment options that may help bring greater stability, independence, and predictability to their lives,” Samantha Masterson, president and CEO of the Myasthenia Gravis Foundation of America, said in a statement.
“Today’s announcement provides another option which could help address the constant uncertainty and heavy physical and mental toll that MG symptom relapse presents to patients and their families,” she added.
Five other drugs to treat gMG have won FDA approval in recent years: eculizumab (Soliris), efgartigimod (Vyvgart), rozanolixizumab (Rystiggo), ravulizumab (Ultomiris), and zilucoplan (Zilbrysq). Of these, eculizumab is the only one indicated for pediatric patients.
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