set plans Thursday to buy
, a company specializing in the development of bio-therapeutics based on monoclonal antibody technology, for $20 a share.
The total value of the transaction is about $919 million. Shares of Tanox surged 44% to $19.64 in pre-market trading Friday.
Genentech and Tanox have been working together with
since 1996 to develop and commercialize Xolair, a monoclonal antibody approved by the Food and Drug Administration in 2003 as a treatment for patients with moderate-to-severe allergic asthma.
As part of the deal, Genentech will also acquire Tanox's product pipeline. Shares of Genentech lost 83 cents to $80.52.