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 two companies now expect to close the acquisition – Amgen’s largest ever – early in the fourth quarter of this year, a spokesperson for Amgen said.

The agreement resolves a lawsuit the FTC filed in May seeking to block the acquisition over concerns it would allow Amgen to leverage its drug portfolio to stifle competition in the pharmaceutical industry. The agency this week temporarily suspended that suit, which allowed it to consider whether to settle the case. 

But the agreement announced Friday still imposes restrictions on Amgen to address key concerns the FTC raised in its suit.

The deal specifically prohibits Amgen from “bundling” two of Horizon’s blockbuster drugs: thyroid eye disease therapy Tepezza and Krystexxa, a gout medicine.

That practice involves offering rebates or discounts on its existing products to pressure insurers and pharmacy benefit managers into favoring the Horizon products.

Amgen will also have to get approval from the FTC to acquire any products that treat the same diseases as Tepezza and Krystexxa do. Amgen is required to seek those signoffs from the agency through 2032.

All other requirements will be effective for 15 years after the agreement is finalized, according to the FTC.

As part of the deal, attorneys general for California, Illinois, Minnesota, New York, Washington and Wisconsin have also agreed to dismiss their federal suits seeking to block the merger.

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

The spokesperson for Amgen said the company has no “reason, ability, or intention” to bundle Horizon’s two fast-growing medications. The new agreement “will have no impact on Amgen’s business,” the spokesperson added.

A Horizon spokesperson did not immediately respond to a request for comment.

Amgen first moved to buy Horizon in December 2022 in an effort to gain access to the latter’s rare disease assets, but buyout was quick to attract regulatory and political scrutiny for its potential antitrust issues.

Sen. Elizabeth Warren, D-Mass., in a letter to FTC Chairwoman Lina Khan asked the regulator to “heavily scrutinize” the acquisition and the then-pending merger of Indivior and Opiant. She warned the deals could lead to higher prices. The Indivior-Opiant deal later closed.

The FTC eventually heeded Warren’s warnings and filed its lawsuit over the Amgen-Horizon deal.

In a separate statement Friday, Khan said the agency will “continue to challenge unlawful practices that raise drug prices, inhibit access, stifle innovation, or otherwise hurt patients.”

The FTC is currently reviewing Pfizer’s $43 billion acquisition of cancer drug developer Seagen, one of the largest deals of this year. The agency started an in-depth investigation into the transaction in July.

The FTC, under Khan, has challenged a number of high-profile mergers. But the agency has struggled in court this year, losing cases to block a Meta deal and Microsoft’s acquisition of Activision Blizzard.