Amgen Inc. in Thousand Oaks has entered an agreement to buy Kirin-Amgen, its joint venture with Japan-based Kirin Holdings Co., for $780 million, the company announced.

“Our historic partnership with Kirin played a pivotal role in the growth of Amgen from a small, venture-backed startup to one of the world’s largest biotechnology companies,” Robert Bradway, chief executive of Amgen, said in a statement.

Amgen and Kyowa Hakko Kirin, the biopharmaceutical arm of Kirin, formed the 50-50 partnership in 1984 to develop Epogen, a drug used to promote the growth of red blood cells in patients with anemia. The joint venture also holds the intellectual property rights to Neulasta and Neupogen, which stimulate white blood cell growth; Aranesp, another drug to treat anemia; Nplate, a platelet booster; and brodalumab, an anti-inflammatory medication that was approved in February by the FDA for the treatment of severe plaque psoriasis.

Kirin-Amgen will pay $780 million in cash to Kirin to become a wholly owned subsidiary of Amgen, according to the company. Amgen will pay up to $30 million more to Kirin upon completion of certain sales. Licensing agreements between Kyowa Hakko Kirin and Amgen in some Asian countries will remain in place, Amgen said. The transaction is expected to close sometime in the late fourth quarter of 2017 or during the first quarter of 2018.

The development was announced late Monday. On Tuesday, Amgen’s stock (AMGN) rose 63 cents, or less than 1 percent, to close at $175.22 on the Nasdaq.