Marking its second acquisition this year after snapping up cancer-focused Five Prime Therapeutics Inc., Amgen Inc. is adding to its inflammatory disease portfolio through the purchase of Seattle-based Rodeo Therapeutics Corp. The deal includes $55 million up front for the private company's shareholders, plus contingent milestone payments worth up to an additional $666 million. Rodeo's lead preclinical program targets 15-prostaglandin dehydrogenase to increase tissue levels of prostaglandin PGE2.