Facing investors unhappy over an unimpressive stock price and its R&D wing being pared down to reduce the bite it takes out of revenue, Amgen announced yesterday that both its CEO and R&D chief are leaving. Kevin Sharer (photo) will step down May 23, and Roger Perlmutter will hand CMO Sean Harper the research reins in February. Meanwhile, COO Bob Bradway will become chief executive. The pair of moves is widely interpreted as a shakeup at the top. Report