Argenx looks for quick label expansion for subcutaneous Vyvgart with PhII data — shares soar

Less than a month after argenx first landed approval of the subcutaneous version of its top drug, the Dutch biotech has notched another win in another rare disease.

The positive data come from a Phase II study of Vyvgart Hytrulo in chronic inflammatory demyelinating polyneuropathy (CIDP), where the drug slashed the risk of relapse by 61% versus placebo (p=0.000039), meeting the primary endpoint in Stage B of the trial, which involved 221 patients.

The company plans to share the data with regulators and file a supplemental BLA for the indication, “ideally by the end of the year,” a company spokesperson said in an emailed statement to Endpoints News.

Cowen analyst Yaron Werber wrote that the data are close to the best-case scenario, supporting $1.5 billion to $2 billion in global sales as argenx looks to expand the use of Vyvgart into new autoimmune conditions.

Shares of argenx soared about 25% on both Belgian and American stock exchanges, reaching €423 in Brussels and $479 on pre-market on the Nasdaq $ARGX.

“We see this clean outcome on the highly anticipated readout as a major clearing event for the company,” Werber wrote.

The study, dubbed ADHERE, enrolled both treatment naïve patients who were not on active treatment within the past six months and those currently on immunoglobulin therapy or corticosteroids.

It began with open-label Stage A, which enrolled 322 patients, with 67% showing evidence of clinical improvement. Those who responded were then enrolled in Stage B.

Investigators also tracked lower relapse rates for patients on Vyvgart Hytrulo at both week 24 (26% versus 54% on placebo) and week 48 (34% versus 60%).

The most side effect was injection site reactions, the company added, which were mild to moderate.

Luc Truyen

In CIDP, patients’ peripheral nerves get damaged over time, leading to fatigue, muscle weakness and a loss of feeling in their arms and legs that can put them in wheelchairs. Intravenous immunoglobulin, or IVIg, is the current standard of care.

Just like the intravenous version, Vyvgart Hytrulo works by binding to the neonatal Fc receptor, thus reducing levels of circulating IgG antibodies. It’s co-formulated using Halozyme’s technology, and in June, it was approved to treat generalized myasthenia gravis.

The new results offer further evidence that IgG autoantibodies play a role in CIDP, argenx CMO Luc Truyen added.

Editor’s note: This story was updated to include supplemental BLA details from a company spokesperson. 

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