(Reuters) -Bristol-Myers Squibb on Sunday said it will acquire cancer drugmaker Mirati Therapeutics for up to $5.8 billion, diversifying its oncology business and adding drugs it hopes can help offset expected lost revenue from patent expirations later this decade. Bristol will pick up Mirati's portfolio drugs that target the genetic drivers of specific cancers including its lung cancer drug, Krazati, which was approved in December. A second compound - MRTX1719 - which could be used in some types of lung cancer was also attractive to the company, Bristol executives said in an interview.