Following the announcement, Argenx shares rose by more than 6 percent in early trading.
Argenx, with bases in the Netherlands and Belgium, has several drugs to treat autoimmune diseases and cancer in various stages of medical trials, often in partnerships with large pharma groups.
It is also developing a cancer immunotherapy drug named ARGX-115 with AbbVie, for which the U.S. company has now decided to trigger an option which gives it an exclusive licence to develop and commercialise the drug.
ARGX-115 is in pre-clinical development, meaning it still has several stages of clinical trials to pass before it could enter the market.
After listing on the stock market in 2014, Argenx's share price has increased tenfold and it joined Belgium's blue-chip index Bel20 <.BFX> earlier this year.
(Reporting by Robert-Jan Bartunek; Editing by Mark Potter)