Novel Therapy Is Approved for Myasthenia Gravis

The FDA granted priority review for this drug due to the longstanding need for a treatment strategy that could improve upon the standard of care.

The FDA granted priority review for this drug due to the longstanding need for a treatment strategy that could improve upon the standard of care. | Image Credit: Postmodern Studio - stock.adobe.com

On April 29, 2025, the FDA approved nipocalimab-aahu (Imaavy) for treating generalized myasthenia gravis (MG) in patients 12 years and older who are positive for antiacetylcholine receptor or antimuscle-specific tyrosine kinase antibodies. Nipocalimab is a human monoclonal antibody that binds neonatal Fc receptors, reducing circulating IgG and significantly relieving symptoms. The FDA granted priority review for this drug due to the longstanding need for a treatment strategy that could improve the standard of care for patients with MG.¹

Efficacy

A 24-week, multicenter, randomized, double-blind, placebo-controlled phase 3 trial (NCT04951622) established the efficacy of nipocalimab for treating MG. Patients enrolled in the study met the Myasthenia Gravis Foundation of America (MGFA) classification II to IV at screening, had a Myasthenia Gravis – Activities of Daily Living (MG-ADL) score of 6 or greater, and maintained a stable standard-of-care regimen for managing MG prior to baseline (ie, acetylcholinesterase inhibitors and/or steroids or nonsteroidal immunosuppressive therapies). Patients with immunodeficiencies not related to MG treatment, classification of MGFA class I at screening, a history of MG crisis within a month before screening or fixed weaknesses, thymectomy within 12 months prior or planned during the study period, allergy to nipocalimab, unstable ischemic heart disease, myocardial infarction, or stroke within 12 weeks of screening visit are excluded from the study.²

In the trial, participants were randomly assigned to receive nipocalimab or placebo infusions in addition to standard-of-care treatment for 24 weeks. Nipocalimab was administered intravenously as a 30-mg/kg loading dose followed by a 15-mg/kg maintenance dose every 2 weeks. The primary efficacy end point of the study compares the mean change in MG-ADL scores from baseline to weeks 22, 23, and 24 between treatment groups. The MG-ADL scale scores the impact of MG symptoms across 8 daily functions. A secondary end point compares the mean change from baseline to weeks 22 and 24 between treatment groups using the Quartermaster-General (QMG) score. The QMG is a clinician assessment that scores disease severity across 13 items. For both tools, higher scores indicate greater disease severity. A statistically significant difference was observed for the primary end point (–1.5 [–2.4, –0.5], P = .002) and secondary end point (–2.8 [–4.2, –1.4], P < .001) in favor of treatment with nipocalimab. Nipocalimab with standard of care provided improved symptom management throughout the study compared with standard of care alone.²

Safety

The most common adverse effects occurring with greater frequency in patients exposed to nipocalimab in trials include infection, peripheral edema, muscle spasm, hypersensitivity reactions, abdominal pain, back pain, fever, diarrhea, cough, anemia, dizziness, nausea, hypertension, and insomnia. Nipocalimab carries a warning to delay administration to any patient with an active infection. Any patient administered nipocalimab should be monitored for signs and symptoms of infection. Serious allergic and infusion-related reactions have occurred with nipocalimab administration. If this occurs, discontinue the infusion, administer appropriate supportive therapy, and assess the risk and benefits of further nipocalimab administration. A clinical concern regarding the use of nivolumab in pregnancy is the potential for reduced passive immunity transferred to the fetus. Nipocalimab is present in breast milk, but there are insufficient data on the effects of nipocalimab on the infant.^1,2

Dosing and Administration

Before initiating nipocalimab therapy, patients should be up-to-date with vaccinations. Live vaccines are not recommended during nipocalimab therapy. Nipocalimab is available as a single dose in 300-mg vials of solution and in 1200-mg vials intended for dilution before administration as an infusion. The drug should be refrigerated and protected from light until use. The loading dose of nipocalimab is a 30-mg/kg intravenous (IV) infusion administered over 30 minutes. Every 2 weeks thereafter, a maintenance dose of 15 mg/kg IV infusion is administered over 15 minutes or longer. If a dose is missed, reschedule as soon as possible and resume therapy with a revised 2-week schedule reflective of the delayed administration date. No dosing adjustments are required for patients with renal or hepatic impairment.¹

To read these stories and more, download the PDF of the Drug Topics July/August issue here.

Ready to impress your pharmacy colleagues with the latest drug information, industry trends, and patient care tips? Sign up today for our free Drug Topics newsletter.