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

ImmunoGen Inc. has the ovarian cancer treatment Elahere.

"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.

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.