The Federal Trade Commission on Friday said it has reached a deal with drug giant Amgen to allow the company’s $27.8 billion purchase of Horizon Therapeutics to move forward. 

The FTC filed a lawsuit in May seeking to block the acquisition, arguing that the deal would “stifle competition” in the pharmaceutical industry. But the agency this week temporarily suspended that suit, which allowed it to consider whether to settle the case. 

Shares of Horizon rose nearly 3% in premarket trading Friday. Amgen’s stock edged up slightly.

Amgen first moved to buy Horizon in December 2022 in an effort to gain access to the latter’s rare disease assets, including the thyroid eye disease therapy Tepezza. 

The buyout was quick to attract regulatory and political scrutiny for its potential antitrust issues.

In its lawsuit, the FTC said that the deal would allow Amgen to “entrench the monopoly positions” of Horizon’s fast-growing medications, including Tepezza, and Krystexxa, a gout medicine.

Specifically, the agency said, Amgen would be able to offer rebates on its existing drugs to pressure insurers and pharmacy benefit managers into favoring the two Horizon products, a strategy known as “cross-market bundling.”

The FTC claimed California-based Amgen has a history of leveraging its drug portfolio to gain advantages over potential rivals.

This story is developing. Please check back for updates.