(Reuters) -Vertex Pharmaceuticals ( VRTX ) will buy Alpine Immune Sciences ( ALPN ) for about $4.9 billion in cash, gaining access to the biotech firm's protein-based immunotherapies to treat autoimmune and inflammatory diseases, the companies said on Wednesday.

The deal values each share of Alpine at $65, which represents a premium of about 67% to the stock's close on Tuesday, a day before Bloomberg News reported that the company was considering options, including a potential sale, after attracting takeover interest.

Shares of Alpine were up 36% in extended trading, while Vertex Pharma was down about 1%.

The gene therapy developer will now have access to Alpine's povetacicept, which is in mid-stage development for the treatment of an autoimmune disease of the kidney called IgA nephropathy (IgAN).

The transaction, approved by Vertex and Alpine's boards, is expected to close in the second quarter of 2024.