Amgen: Epogen, a Kirin Brewery Deal and the Undruggable KRAS Target

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Amgen started in 1980 in Thousand Oaks, California, as Applied Molecular Genetics, backed by venture capitalists betting on recombinant DNA, with George Rathmann as CEO. In 1983 a team led by Fu-Kuen Lin cloned the erythropoietin gene by hand, without automated sequencers, work that became the anemia drug Epogen. FDA approval did not come until 1989, so Amgen went public in 1983, raising nearly $40 million, and in 1984 formed a joint venture with Japan's Kirin Brewery, whose fermentation expertise carried over to growing drugs in living cells, in exchange for Japanese rights.

Larry Souza cloned G-CSF, leading to the 1991 approval of Neupogen, which helps restore white blood cells after chemotherapy, and Steve Elliott's added sugar molecules made the longer-lasting Aranesp. Later, under Kevin Sharer and Robert Bradway, Amgen bought Otezla, Five Prime Therapeutics, ChemoCentryx and, for $27.8 billion in 2023, Horizon Therapeutics. Revenue reached almost $37 billion by 2025. In 2012 Amgen pleaded guilty and paid $762 million over off-label marketing of Aranesp, and in 2025 a jury ordered it to pay Regeneron $406 million over anticompetitive practices tied to Repatha.

• Amgen opened a manufacturing plant in Puerto Rico in 1993 and received the National Medal of Technology in 1994.
• Lumakras, approved in 2021, targets the KRAS mutation in lung cancer through a hidden groove that opens only in a specific state.
• In late 2023 Amgen partnered with Amazon Web Services to apply generative AI to drug discovery and manufacturing.
• Trial doses of MariTide, a monthly obesity injection, were lowered in 2025 over vomiting, though patients who stayed on it lost about 20 percent of body weight.
• Amgen announced a $900 million facility expansion in Ohio and a $600 million research center in California.