 Even after recently agreeing to shell out 11.5 billion to acquire Acceleron Pharma Inc. XLRN , Financial, Merck Co. Inc. MRK , Financial says its not done in its quest for deals aimed at diversifying its business. The more than 200 billion pharmaceutical giant wants to expand its offerings to soften the blow when its mega-blockbuster drug, Keytruda, loses patent protection around 2028, according to FiercePharma. 