By David Shepardson
WASHINGTON (Reuters) - The states of California, New York, Illinois, Minnesota, Washington and Wisconsin have joined a Federal Trade Commission (FTC) lawsuit to stop Amgen (NASDAQ:AMGN)'s $27.8 billion deal to buy Horizon Therapeutics (NASDAQ:HZNP), according to a court filing on Thursday.
Washington Attorney General Bob Ferguson said his state had joined the lawsuit because "monopolies harm consumers" and the merger could allow Amgen to "dominate" prescription drug markets.
The group of six states filed an amended complaint Thursday, joining the FTC which last month filed suit opposing the deal because it would give Amgen "monopoly positions" for medicines used to treat thyroid eye disease and chronic refractory gout.
"Amgen's proposed acquisition of Horizon is dangerous for the future of medicine, dangerous for innovation and research, and most importantly, dangerous for sick people in need of often lifesaving drugs," California Attorney General Rob Bonta said.
The FTC acquisition marks a change for the agency, which previously had typically flagged therapeutic overlaps in companies and waved deals through after requiring one of the medicines to be divested.
Amgen said in a statement last month it was disappointed by the FTC decision and it believed it had "overwhelmingly demonstrated" that the deal had no legitimate competitive issues.
Amgen announced plans to buy Horizon in December, saying that its rare disease drugs would offer it some protection from the drug pricing provisions of the Inflation Reduction Act, which are aimed at drugs most widely used by the government's Medicare health plan.
The last major pharmaceutical deal approved by the FTC was AstraZeneca (NASDAQ:AZN)'s $39 billion acquisition of Alexion (NASDAQ:ALXN) Pharma in April 2021, about two months before FTC Chair Lina Khan was appointed by the Biden administration.