The Food and Drug Administration (FDA) has accepted for Priority Review the Biologics License Application (BLA) for the subcutaneous (SC) formulation of efgartigimod for the treatment of generalized myasthenia gravis (gMG) in adults.

The SC formulation of efgartigimod is coformulated with recombinant human hyaluronidase PH20 (rHuPH20) and Halozyme’s ENHANZE drug delivery technology, which facilitates the SC injection delivery of biologics that are typically administered via intravenous (IV) infusion.

The BLA is supported by data from the randomized, open-label, parallel-group phase 3 ADAPT-SC study (ClinicalTrials.gov Identifier: NCT04735432) that compared the efficacy and safety of SC efgartigimod to IV efgartigimod (Vyvgart) in adults with gMG. Patients were randomly assigned 1:1 to receive either SC or IV efgartigimod once weekly for 1 treatment cycle consisting of 4 doses for a total study duration of 12 weeks. The primary endpoint was the percent change from baseline in total immunoglobulin (IgG) levels at day 29.

Results showed that treatment with SC efgartigimod met the primary endpoint demonstrating noninferiority to IV efgartigimod (P <.0001). At day 29, patients treated with SC efgartigimod achieved a mean total IgG reduction of 66.4% compared with a 62.2% reduction for IV efgartigimod. These findings were consistent in the overall population regardless of anti-acetylcholine receptor (AChR) antibodies. 

Additionally, treatment with SC efgartigimod met key secondary endpoints with 69.1% and 65.5% of patients being responders on the Myasthenia Gravis Activities of Daily Living (MG-ADL) score and the Quantitative Myasthenia Gravis (QMG) score, respectively. Responders were defined as having at least a 2-point improvement on the MG-ADL score and at least a 3-point improvement on the QMG score for at least 4 consecutive weeks.

The safety profile of SC efgartigimod was generally well tolerated and consistent with that seen with the IV formulation. The most common adverse reactions were injection site reactions.

A Prescription Drug User Fee Act (PDUFA) target date of March 20, 2023 has been set for this application.

Efgartigimod is currently marketed under the trade name Vyvgart and is indicated for the treatment of gMG in adults who are AChR antibody positive. Vyvgart is available as a 20mL single-dose vial containing 400mg of efgartigimod alfa-fcab for intravenous infusion after dilution.

Reference

argenx announces US FDA acceptance of Biologics License Application for subcutaneous efgartigimod in generalized myasthenia gravis with Priority Review. News release. argenx SE. Accessed November 22, 2022. https://www.globenewswire.com/news-release/2022/11/22/2560417/0/en/argenx-Announces-U-S-FDA-Acceptance-of-Biologics-License-Application-for-Subcutaneous-Efgartigimod-in-Generalized-Myasthenia-Gravis-with-Priority-Review.html.