The first wave of biosimilars began lapping at U.S. shores five years ago when the FDA approved Sandoz Inc.’s Zarxio on March 6, 2015, giving it a label identical to that of its reference biologic, Amgen Inc.’s Neupogen (filgrastim). But the tsunami of biosimilars, and the multibillion dollars of savings they were expected to bring, has yet to wash ashore.