A novel human antibody fragment is under review by the US Food and Drug Administration (FDA) as a treatment for myasthenia gravis (MG) following the submission of a Biologics License Application, according to a recent press release from Argenx SE.

“Every individual experiences generalized MG 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.

Efgartigimod is an antibody fragment that blocks the neonatal Fc receptor, translating into an impaired immunoglobulin G (IgG) recycling process and hence, decreasing the concentration of IgG autoantibodies. This molecule is available in 2 presentations, suitable for either intravenous (IV) or subcutaneous (SC) administration.

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The SC efgartigimod formulation has recombinant human hyaluronidase PH20 as an additional component. This technology aids in proper drug availability regardless of being administered subcutaneously. The presentation of SC efgartigimod recently submitted for review has a concentration of 100 mg efgartigimod-PH20 per unit.

The efficacy of the SC administration was demonstrated in the ADAPT-SC study, a phase 3 trial that aimed to assess the noninferiority of this route vs the IV formulation. The researchers included adult patients previously diagnosed with MG. Most of them had acetylcholine receptor (AChR) autoantibodies.

Both formulations showcased a total IgG reduction at the 29-day follow-up compared to baseline measurements. Notably, the SC group had a 66.4% reduction, while the participants who received the IV drug had a 62.2% overall IgG reduction. These results were replicated in both the AChR positive and negative patients.

Moreover, SC efgartigimod produced a 2-point or more improvement in the Myasthenia Gravis Activities of Daily Living score and at least a 3-point improvement in the Quantitative Myasthenia Gravis score in 69.1% and 65.5% of the cases, respectively. Finally, 37% achieved a symptom-free status as determined by the Minimal Symptom Expression.

Reference

Argenx submits Biologics License Application to U.S. Food and Drug Administration for subcutaneous efgartigimod for treatment of generalized myasthenia gravis. News release. Argenx SE; September 21, 2022.