Roche Madison, formerly part of Mirus Bio Corp., has been purchased by Arrowhead Research Corp. of Pasadena, Calif. Roche Madison, 545 Science Drive in University Research Park, has more than 40 scientists who will stay with the company, according to Monday?s announcement. Mirus Bio was founded in 1995 based on UW-Madison research and developed a platform using RNA interference technology that turns off certain genes, for use in drug discovery. That division was split off and sold to Roche in 2008 for $125 million.