AbbVie is buying ImmunoGen in a deal valued at about $10.1 billion with the goal of speeding the pharmaceutical's entry into the market for ovarian cancer treatments.

ImmunoGen Inc. developed the ovarian cancer drug Elahere, which AbbVie says it sees as a potential multibillion-dollar future revenue generator.

"The acquisition of ImmunoGen demonstrates our commitment to deliver on our long-term growth strategy and enables AbbVie to further diversify our oncology pipeline across solid tumors and hematologic malignancies,” AbbVie Chairman and CEO Richard Gonzalez said in a statement on Thursday.

AbbVie will pay $31.26 per share in cash for each ImmunoGen share.

Both companies' boards have approved the transaction, which is expected to close in the middle of 2024. It still needs approval from ImmunoGen shareholders and regulators.

U.S. regulators granted Elahere an accelerated approval in 2022, and the company is seeking a full approval from the Food and Drug Administration as well as expansion in other markets. It also plans to expand Elahere's use.

ImmunoGen said Elahere brought in $105.2 million in revenue in this year’s third quarter, or nearly all of the company’s total sales.

AbbVie has been dealing this year with cheaper competition for its top seller, the autoimmune disease treatment Humira. The injectable biologic drug is used to treat rheumatoid arthritis, Crohn’s disease and ulcerative colitis.

Humira brought in $21 billion in total revenue last year, or about 36% of AbbVie's total. The biologic treatment brought in more than $20 billion in 2021.

Shares of ImmunoGen soared more than 82% before the market open, while AbbVie's stock fell slightly.