In May, the FTC had opposed the acquisition, arguing that Horizon had a monopoly position with its drugs in the US in the fight against certain diseases.

But the FTC attaches conditions to its approval: Amgen may not bundle any of its products with Horizon's Tepezza or Krystexxa, nor may it use rebates or contract terms to disadvantage competing products. In addition, Amgen may acquire potential competing products to Horizon drugs only with the FTC's permission.

As a result of the agreement with the FTC, Amgen and Horizon expect to jointly file stipulated proposed orders to dismiss the preliminary injunction motion and dissolve the temporary restraining order (TRO) in the US District Court for the Northern District of Illinois, and that the companies will quickly seek the final approvals required under Irish law to close the acquisition.

Amgen and Horizon anticipate being able to close the acquisition in early fourth-quarter 2023 and look forward to the opportunity to serve patients around the world suffering from rare diseases.