Amgen Inc. plans a campaign of stock buybacks and dividends that will return 60 percent of the biotechnology drug company’s adjusted earnings to shareholders through 2018. [...] Point, the hedge fund firm run by Daniel Loeb, called this month for Amgen to split into two companies, one with older drugs and one with new prospects. Kyprolis, acquired in last year’s purchase of Onyx Pharmaceuticals Inc., has been approved for multiple myeloma and is in clinical trials with earlier-stage patients. The Food and Drug Administration’s standards for biosimilar approval are “relatively high,” said Vice President Scott Foraker, but Amgen has a competitive advantage because of its biologics capabilities.