Argenx's Vyvgart Hytrulo Becomes First FDA Approved Subcutaneous Option For Generalized Myasthenia Gravis

The FDA has approved Argenx SE's ARGX Vyvgart Hytrulo (efgartigimod alfa and hyaluronidase-qvfc), an injection for subcutaneous (SC) use for generalized myasthenia gravis (gMG) in adult patients who are anti-acetylcholine receptor antibody positive. 

These patients represent approximately 85% of the total gMG population.

Vyvgart Hytrulo is a subcutaneous product combination of efgartigimod alfa, a human IgG1 antibody fragment marketed for intravenous use as Vyvgart, and recombinant human hyaluronidase PH20 (rHuPH20), Halozyme Therapeutics Inc's HALO ENHANZE subcutaneous drug delivery technology.

A healthcare professional will administer the product subcutaneously as a single injection (1,008 mg fixed dose) over 30-90 seconds in cycles of once-weekly injections for four weeks.

The FDA approval is based on results from the Phase 3 ADAPT-SC study and it was a bridging study to the Phase 3 ADAPT study, which formed the basis for approval of intravenous Vyvgart in December 2021.

In the ADAPT-SC study, the primary endpoint of noninferiority was met, and Vyvgart Hytrulo demonstrated a mean total IgG reduction of 66.4% from baseline at day 29, compared to 62.2% with Vyvgart.

Vyvgart Hytrulo is expected to be available in the U.S. in July 2023. 

Marketing authorization applications for SC efgartigimod are under review by the European Medicines Agency and Japanese regulatory authority, with decisions expected by the end of 2023 and Q1 of 2024, respectively.

William Blair analyst expects that the pricing of Vyvgart Hytrulo will be "at parity to Vyvgart on a net annual revenue basis," which is about $225,000/year. 

It also notes that other SC-administered injectables in adjacent indications like SCIg Takeda Pharmaceutical Co Ltd TAK Hyqvia) or AstraZeneca Plc's AZN Ultomiris can be self- or caregiver-administered.

Price Action: ARGX shares are down 0.91% at $397.64 on the last check Wednesday.