Private equity firm Advent International is considering a potential purchase of drugmaker Swedish Orphan Biovitrum AB, people with knowledge of the matter said.

Advent is leading a consortium that’s exploring an acquisition of the Swedish biotech firm, the people said, asking not to be identified because the information is private. It has reached out to other buyout firms including Permira to gauge their interest in teaming up on the potential deal for Sobi, according to the people.

Advent is also considering roping in sovereign wealth funds to join a bid, the people said. Discussions are at a preliminary stage, and there’s no certainty they will lead to a transaction, the people said.

Sobi has for years been seen as a potential takeover target for rival drugmakers or buyout firms. In 2015, the company said it ended talks on a possible takeover offer after reports that Pfizer Inc. and Biogen Inc. were among interested parties. Any suitor would need to win the backing of Investor AB, the investment vehicle owned by the billionaire Wallenberg family, which controls about 35% of the biotech company.

Representatives for Advent, Sobi and Investor AB declined to comment, while a spokesperson for Permira couldn’t immediately comment.

Sobi has built itself up through acquisitions. In 2019, the company bought Dova Pharmaceuticals Inc. for almost $1 billion to expand in hematology. The year earlier, Sobi agreed to buy the U.S. rights to the respiratory medicine Synagis from AstraZeneca Plc. Upon completion of that deal, AstraZeneca gained an 8.1% stake in Sobi.