Horizon Therapeutics plc Responds to U.S. Federal Trade Commission (FTC) Action to Block Acquisition by Amgen

Horizon Therapeutics plc (Nasdaq: HZNP) today issued the following statement in response to the FTC's complaint seeking to block Amgen's proposed acquisition of the Company:

"This acquisition has the potential to accelerate the availability of important rare disease medicines to more patients worldwide. The FTC's complaint impacts patients and is rooted in a theory about potential future "bundled" contracts with payors and not competitive overlap concerns. Horizon does not and has no plans to bundle any of its rare disease medicines. It is imperative that we continue to advocate for access to innovative treatments for patients who may benefit, particularly in diseases with significant unmet needs, and the proposed transaction with Amgen is part of that mission. We firmly believe in the benefits of this acquisition and intend to work with the court on a schedule that would allow the transaction to close by mid-December."

About Horizon

Horizon is focused on the discovery, development and commercialization of medicines that address critical needs for people impacted by rare, autoimmune and severe inflammatory diseases. Our pipeline is purposeful: We apply scientific expertise and courage to bring clinically meaningful therapies to patients. We believe science and compassion must work together to transform lives. For more information on how we go to incredible lengths to impact lives, visit www.horizontherapeutics.com and follow us on Twitter, LinkedIn, Instagram and Facebook.

Forward-Looking Statements

This announcement contains forward-looking statements, including statements regarding Horizon's future prospects, developments and business strategies, the potential outcome of litigation with the FTC and the timing and benefits of the proposed transaction with Amgen. These forward-looking statements are based on management expectations and assumptions as of the date of this announcement, and actual results may differ materially from those in these forward-looking statements as a result of various factors. These factors include risks regarding the ability of the parties to consummate the proposed transaction in a timely manner or at all; the satisfaction (or waiver) of conditions to the consummation of the proposed transaction, including with respect to required regulatory approvals and absence of orders preventing the closing of the proposed transaction; potential delays in consummating the proposed transaction; the occurrence of any event, change or other circumstance or condition that could give rise to the termination of the Transaction Agreement; and the outcome of the litigation with the FTC or any other legal proceedings that have or may be instituted against the parties or any of their respective directors or officers related to the proposed transaction. Additional risks and uncertainties that could cause actual outcomes and results to differ materially from those contemplated by the forward-looking statements are included under the caption "Risk Factors" and elsewhere in Horizon's most recent filings with the SEC, including its Annual Report on Form 10-K for the year ended December 31, 2022, and any subsequent reports on Form 10-Q or Form 8-K filed with the SEC from time to time and available at https://www.sec.gov/. These documents can be accessed on Horizon's website at https://ir.horizontherapeutics.com/financial-information/sec-filings. The forward-looking statements set out in this announcement are made only as of the date hereof. Horizon assumes no obligation and does not intend to update these forward-looking statements, except as required by law.