Dutch Belgian biotech company Galapagos is ending its efforts to develop a cancer treatment and plans to wind down its entire cell therapy division after failing to sell the unit.

The move means the company’s research centre in Leiden will close, along with sites in Basel, Princeton, Pittsburgh and Shanghai.

Around 365 people work in the division, all of whom are expected to lose their jobs, Galapagos said in a press statement. The company must still reach agreement with employee works councils before the closures can go ahead.

Shares in Galapagos fell by around 15% on the Amsterdam stock exchange following the announcement, though the loss was partly recovered later in the day.

Five years ago, Galapagos was seen as one of the most promising biotech firms on the market. US company Gilead invested some €4.5 billion in a close partnership with the Dutch-Belgian group, but investor confidence has waned in recent years after several new drug programmes failed to deliver breakthroughs.

Tuesday’s announcement means just a handful of jobs will remain at the company’s Belgian headquarters. Several years ago Galapagos had a workforce of some 1,500.

Chief executive Henry Gosebruch, who took over earlier this year, had initially sought to sell the cell therapy business. Although several parties expressed interest, Gosebruch said the few bids received were not viable.

As a result, the board decided to wind down the cell therapy operations and potentially shut them down entirely, though the company said it may still sell some or all of the activities in the future.

Galapagos, founded in 1999, described the move as a unanimous decision by the board, but two Gilead-appointed directors abstained from voting, according to the company’s press release.