Imaavy Approved for Generalized Myasthenia Gravis

The Food and Drug Administration (FDA) has approved Imaavy^™ (nipocalimab-aahu) for the treatment of generalized myasthenia gravis (gMG) in adult and pediatric patients aged 12 years and older who are anti-acetylcholine receptor (AChR) or anti-muscle-specific tyrosine kinase (MuSK) antibody positive.

Nipocalimab-aahu is a human immunoglobulin G1 (IgG1) monoclonal antibody that binds with high affinity to the neonatal Fc receptor (FcRn), resulting in the reduction of circulating IgG levels. The approval was supported by data from the randomized, double-blind, placebo-controlled phase 3 Vivacity-MG3 study (ClinicalTrials.gov Identifier: NCT04951622), which enrolled adults with gMG (Myasthenia Gravis Foundation of America clinical classification class II to IV) who had an insufficient response (defined as Myasthenia Gravis – Activities of Daily Living [MG-ADL] score of at least 6) to ongoing standard of care therapy.

Study participants were randomly assigned to receive nipocalimab (n=98) or placebo (n=98) by intravenous (IV) infusion once every 2 weeks. The primary endpoint was the comparison of the mean change from baseline to weeks 22, 23, and 24 between treatment groups in the MG-ADL total score. 

The MG-ADL scale assesses the impact of gMG on daily functions of 8 signs and symptoms that are typically affected in gMG (talking, chewing, swallowing, breathing, impairment of ability to brush teeth or comb hair, impairment of ability to arise from a chair, double vision, eyelid droop). Total scores range from 0 to 24 with higher scores indicating more impairment.

The primary efficacy analysis population included 153 patients. At baseline, the median MG-ADL and Quantitative Myasthenia Gravis (QMG) total scores were 9 and 15, respectively; 88% of patients were positive for AChR antibodies and 10% were positive for MuSK antibodies.

At week 24, findings showed treatment with nipocalimab resulted in a statistically significant improvement in MG-ADL total score compared with placebo (-4.7 vs -3.3; least squares [LS] mean difference, -1.5 [95% CI, -2.4, -0.5]; P =.002). Efficacy was also measured using QMG total score (secondary endpoint; range: 0-39, with higher scores indicating more severe impairment). A statistically significant difference favoring nipocalimab was observed in the QMG total score change from baseline (-4.9 vs -2.1; LS mean difference, -2.8 [95% CI, -4.2, -1.4]; P <.001).

The most common adverse reactions reported with treatment were respiratory tract infections, peripheral edema, and muscle spasms. In clinical trials, infections, hypersensitivity reactions, and infusion-related reactions were observed in patients who received nipocalimab.

Imaavy is supplied as a 300mg/1.62mL and 1200mg/6.5mL single-dose vial. Prior to beginning treatment, patients should be evaluated for the need to administer-age appropriate vaccines; vaccination with live vaccines during treatment is not recommended. 

Treatment is administered every 2 weeks via IV infusion after dilution. The initial dose should be infused over at least 30 minutes; subsequent maintenance doses are infused over at least 15 minutes.

Imaavy is expected to be available in May 2025.

This article originally appeared on MPR