Arcus Biosciences Inc. “brings the milk without [Gilead Sciences Inc.] having to buy the whole cow” is the way one analyst characterized the pair’s 10-year cancer immunotherapy deal, which could be worth as much as $2 billion, and some may have detected downside for Arcus, as shares (NYSE:RCUS) closed May 27 at $27.05, down $6.49, or 19%. Foster City, Calif.-based Gilead is paying Arcus, of Hayward, Calif., $175 million up front, shelling out a $200 million equity investment, and pledging potentially $1.6 billion or more in the form of R&D support, opt-in cash and milestone payments.