Thursday, Argenx SE ( ARGX ) shares are trading higher in reaction to Chugai Pharmaceutical Co Ltd’s disappointing generalized myasthenia gravis trial, pushing the company’s market cap to $21.2 billion as per data from Benzinga Pro.

In June 2023, the FDA approved Argenx’s Vyvgart Hytrulo, an injection for subcutaneous (SC) use for generalized myasthenia gravis in adult patients who are anti-acetylcholine receptor antibody positive. These patients represent approximately 85% of the total gMG population.

Vyvgart intravenous injection for gMG was approved in December 2021.

Thursday, Chugai, a Japanese biotech, released results from the Phase 3 LUMINESCE study of Enspryng (satralizumab), an investigational treatment for generalized myasthenia gravis (gMG). 

The company said that although statistically significant data was observed in its primary endpoint, the results did not reach expectations regarding the degree of clinical benefit. 

Enspryng was well tolerated in gMG, with a safety profile consistent with Enspryng in neuromyelitis optica spectrum disorder (NMOSD), the medicine’s first indication. 

Detailed results will be presented at the American Academy of Neurology 2024 Annual Meeting on 15 April.

The company says the results from the gMG study do not impact Enspryng in NMOSD, for which the medicine has already been approved. 

Chugai, in collaboration with Roche Holdings AG (OTC:RHHBY), is developing Enspryng in additional neurological autoimmune and inflammatory diseases.

Argenx’s 2023 product revenues solely came from Vyvgart and generated global net product revenues (inclusive of both Vyvgart and Vyvgart SC) of $374 million in the fourth quarter and $1.2 billion in FY2023.

Recently, Johnson & Johnson’s Phase 3 VIVACITY study of nipocalimab in gMG met the primary endpoint, achieving a statistically significant reduction in MG-ADL score from baseline over weeks 22 to 24 compared with placebo. 

Price Action: ARGX shares are up 14.6% at $409.12 on the last check Thursday.