Subcutaneous Efgartigimod for Generalized Myasthenia Gravis Submitted to FDA for Approval

An application was submitted to the Food and Drug Administration (FDA) for subcutaneous efgartigimod (Argenx SE, Amsterdam, Netherlands) for the treatment of generalized myasthenia gravis (gMG) in adults.

Submission is based on data from the phase 3 ADAPT-SC study (NCT03669588) showing subcutaneous efgartigimod was not inferior to intravenous efgartigimod (Vyvgart; Argenyx) in participants with gMG. Most enrolled participants were positive for acetylcholine receptor (AChR) antibodies, although there were participants in whom antiAChR were not detected.

Results from the phase 3 trial include: 

•    Mean total IgG reduction of 66.4% from baseline at day 29 in participants treated with subcutaneous efgartigimod, compared with 62.2% reduction with intravenous efgartigimod. 
•    69.1% of participants treated with subcutaneous efgartigimod had at least a 2-point improvement on the Myasthenia Gravis Activities of Daily Living (MG-ADL) score for at least 4 consecutive weeks.
•    65.5% of patients treated with subcutaneous efgartigimod had at least a 3-point improvement on the Quantitative Myasthenia Gravis (QMG) score for at least 4 consecutive weeks.
•    Minimal symptom expression (MSE) was achieved in 37% of participants treated with subcutaneous efgartigimod after 1 treatment cycle.
•    Results were consistent across individuals with and without antiAChR.

“Our vision for the gMG program is to deliver the broadest treatment offering for people living with this debilitating and often overlooked disease. Every individual experiences gMG differently, which is why we’re excited about the possibility of introducing multiple ways to meet the needs of patients, including with route of administration and dosing schedule,” said Tim Van Hauwermeiren, chief executive officer of Argenx. “The submission of this BLA is the latest milestone in honoring our commitment to the gMG patient community. We look forward to working closely with the agency through the BLA review process and to potentially bringing forth another first-in-class option for gMG patients.”

Subcutaneous efgartigimod is devised with recombinant human hyaluronidase PH20 (rHuPH20) drug delivery technology. Efgartigimod is thought to improve gMG through inhibition of IgG recycling, which results in more lysosomal destruction of IgG and overall lower levels of IgG. 

The most common adverse event was injection site reactions (ISRs), commonly observed with biologics administered subcutaneously.