FTC Files Lawsuit To Prevent Amgen From Acquiring Manufacturer of Tepezza, Krystexxa

Acquiring Tepezza and Krystexxa would give Amgen a monopoly on those treatments, which it could then use to smother competition, the FTC warns

Federal regulators have filed a lawsuit seeking to stop a $27.8 billion deal by Amgen to acquire Horizon Therapeutics, the makers of Tepezza, Krystexxaand and other drugs, which would give the biopharmaceutical company a monopoly over the treatment of certain conditions.

The complaint (PDF) was filed by the Federal Trade Commission (FTC) in the U.S. District Court for the Northern District of Illinois on May 16, seeking a temporary restraining order and preliminary injunction preventing the sale of Horizon Therapeautics, Inc. to Amgen.

The FTC lawsuit claims that giving Amgen control of Horizon’s portfolio of drugs, particularly the thyroid eye disease (TED) drug Tepezza, and the chronic refractory gout (CRG) drug Krystexxa, will “substantially lessening competition in the markets for the sale of FDA-approved drugs to treat TED and CRG”, which could lead to Amgen having a monopoly on drugs that treat those conditions.

The filing comes in response to a deal announced in December, when Amgen agreed to pay $116.50 per share in cash to acquire Horizon.

While the acquisition was originally announced as being worth $28.5 billion, the FTC says the deal is worth $27.8 billion.

Investors have expressed concerns over the deal as well, as it comes as Horizon faces a growing number of Tepezza lawsuits, involving claims that the drug has caused users to suffer irreversible hearing loss. Plaintiffs say the drug maker knew or should have known about the risk, but withheld critical safety warnings and information from the medical community and patients.

Tepezza Lawsuits

Do You Have Hearing Loss from Tepezza?

Side effects of Tepezza may cause permanent hearing problems. Lawsuits are being pursued over the drug maker's failure to warn about the risk. Find out if qualify for a settlement.


The FTC filed the lawsuit over concerns about the growing reach of Amgen and its dominance in some sectors of the pharmaceutical industry.

“Through a number of acquisitions, Amgen has grown into one of the largest biopharmaceutical companies in the world,” the complaint states. “Its proposed acquisition of Horizon, valued at $27.8 billion, would be by far Amgen’s largest ever purchase. Each acquisition has successfully expanded Amgen’s product portfolio, thereby increasing its leverage in negotiations over its products’ availability and reimbursement rates.”

The FTC notes that Tepezza and Krystexxa are already monopoly products, and giving control of them to Amgen could result in the company using multi-product contracts and rebates to sustain, entrench and increase its influence over pricing by controlling those monopolies and bundling the must-have drugs with other products.

“There are no countervailing factors sufficient to offset the likelihood of competitive harm from the Proposed Acquisition,” the FTC argues. “Neither entry nor expansion by other market participants would be timely, likely, or sufficient in its magnitude, character, and scope to deter or counteract the Proposed Acquisition’s anticompetitive harm.”

Tepezza Hearing Loss Concerns

A number of studies and case reports have been published over the last two years, which identified a link between Tepezza and hearing side effects, which critics indicate the manufacturer knew or should have known about before the drug was ever introduced.

While the drug’s warning label does mention hearing loss as a possible risk of Tepezza, lawsuits allege that the drug maker downplays the problems as temporary, and that many users could have avoided permanent hearing loss of instructions had been provided about the importance of monitoring hearing on Tepezza.

In a study published earlier this year in the American Journal of Ophthalmology, Stanford researchers looked at 27 patients who had received at least four Tepezza injections and followed up with them up to 40 weeks later, finding that more than 80% of patients receiving Tepezza suffered some form of hearing problems.

review of that study, published in August 2022, found that about one-third of all patients who experienced Tepezza hearing loss still suffered problems months after receiving the injections.

Given similar allegations raised in a growing number of hearing loss lawsuits over Tepezza, the U.S. Judicial Panel on Multidistrict Litigation (JPML) is scheduled to hear oral arguments next week about whether to consolidate the litigation against Horizon Therapeutics before one judge, to reduce duplicative discovery into common issues in the claims, and to avoid conflicting pretrial schedules and rulings.

Horizon Therapeutics has opposed centralization of the Tepezza infusion lawsuits, maintaining that there are currently too few claims to justify the formal consolidation. However, the number of cases has been steadily increasing, and is widely expected to include several hundred hearing loss claims by the end of this year.


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