Argenx's (ARGX) Q4 sales of $737 million, up 29% quarter-on-quarter, were backed by increasing Vyvgart usage through prescriber breadth and depth, Oppenheimer said in a note to clients Friday.

The investment firm said Q4's "significant beat" was largely due to Vyvgart's chronic inflammatory demyelinating polyneuropathy indication, with uptake outpacing estimates, as there were no major changes in the myasthenia gravis dynamics. Vyvgart's growth was driven mainly by the US market, as sales outside the US only grew modestly, according to the note.

Label-expansion studies for Vyvgart and phase 4 treatment decisions are expected to further facilitate usage, the investment firm said.

Oppenheimer also highlighted the approximately 25% increase in the company's 2025 guidance for research and development spending as well as selling, general and administrative expenses to about $2.5 billion, with 10 phase 3 studies and 10 phase 2 trials still ongoing.

Oppenheimer raised Argenx's price target to $704 from $675, and maintained the stock's outperform rating.

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