Around 22 Irish-based jobs are at risk following a decision by biotechnology company Amgen to lay off 350 workers at Horizon Therapeutics.
It follows the clearance of Amgen's purchase of the Irish-headquartered drug company less than three weeks ago in a $27.8 billion deal.
The bulk of the 350 job losses will impact staff in Deerfield in Illinois, according to reports in the Chicago Tribune.
In a statement, Amgen said its total Irish workforce is now around 1,250 people inclusive of legacy Horizon staff.
"In Ireland, less than 2% of the combined Amgen/legacy Horizon workforce will receive notification that their role has been identified for consultation," a spokesperson said.
"We are not providing numbers for individual locations," the company added.
Amgen also said it will be evaluating its site in Waterford.
"Waterford is now an Amgen site and will become part of the network-wide evaluations that we continually carry out to consider our supply options to ensure reliable and efficient supply for patients," Amgen said in a statement.
"It will take some time to assess this in conjunction with our entire network capabilities and capacity," the company added.
Amgen also said today that about 80% of Horizon's workers will be placed into jobs at Amgen.
The 350 who are being laid off are losing their jobs largely because of "overlap with existing teams at Amgen," Amgen added.
The company said that no jobs will be terminated before the end of December of this year.
"We do not take these decisions lightly, and we appreciate the contributions of those employees being impacted," Amgen said in the statement. "We will treat them with respect and offer support through the process."
Horizon sold orphan drugs, which are medications for rare diseases, and drugs to treat rheumatic diseases. Amgen is a large drugmaker based in California.
When asked what will become of Horizon's Deerfield offices - a three-building, 650,000-square-foot campus visible from I-94 - an Amgen spokeswoman told the Chicago Tribune that "Horizon has made a significant investment in the Chicago community, and we are committed to a footprint in Deerfield."
Horizon decided in 2020 to relocate its US headquarters from Lake Forest to the campus, which was previously home to the US headquarters of Takeda Pharmaceutical Co.
Horizon was founded in 2008. It bestselling drug was Tepezza, for thyroid eye disease, which came from a company it bought in 2017. Its second-bestselling drug was Krystexxa, a drug for uncontrolled gout.
Amgen's top-selling drugs are Enbrel, for rheumatoid arthritis, and Prolia, for osteoporosis.
Horizon had sales of $945m and Amgen had sales of $6.7 billion in the three months to the end of June.
The two companies first announced the acquisition deal late last year.
It was cleared earlier this month after it received the go-ahead from the US Federal Trade Commission (FTC) last month on certain conditions.
Under the settlement terms with the FTC following its lawsuit to block the deal, Amgen is prevented from using anticompetitive tactics to extend the market dominance of Horizon's thyroid eye disease treatment Tepezza and gout drug Krystexxa.
The FTC's antitrust lawsuit had raised concerns over increased oversight on mergers and acquisitions in a sector that often turns to consolidation to power future growth as patents on older treatments expire.
The deal closure was within the fourth-quarter timeline set by the two companies.
