Roche buys Mirus Bio Corp. for $125 million

The announcement came a day after Roche offered $43.7 billion for the remaining shares of U.S. biotech pioneer Genentech Inc.

Madison, Wis.-based Mirus Bio is developing RNAi, or gene silencing, a technology that uses mechanisms within the body to target and "turn off" certain genes associated with cancer and other diseases.

Roche said it will maintain a RNAi research site in Madison after the takeover. The move is expected to be completed during the second half of this year, Roche said.

Last year, Roche acquired rights for the gene-silencing technology of biotechnology company Alnylam Pharmaceuticals Inc. as part of a deal potentially worth $1 billion.