Global biopharmaceutical firm Amgen Inc. (Nasdaq: AMGN) has agreed to buy KAI Pharmaceuticals, a privately held company based in San Francisco, for $315 million in cash.

It will acquire worldwide rights, excluding Japan, to KAI Pharmaceuticals' lead product candidate, KAI-4169, which treats secondary hyperparathyroidism, or SHPT, in patients with chronic kidney disease, or CKD.

SHPT is commonly caused by CKD.

As a part of the agreement, Thousand Oaks, Calif.-based Amgen said it will also offer the San Francisco-based company a loan to allow it to further develop KAI-4169, an experimental therapy administered intravenously at the same time a CKD patient is undergoing dialysis. KAI-4169 is in Phrase 2 of clinical development.

KAI has demonstrated encouraging results in the clinic. We are excited about acquiring KAI, as well as the opportunity to potentially deliver a novel therapy for chronic kidney disease patients on dialysis suffering from secondary hyperparathyroidism, said Sean E. Harper, executive vice president of Research and Development at Amgen, in a press release.

Shares of Amgen rose 0.94 percent in late morning trading in a day the Dow Jones Industrial Average rose 0.79 percent.