Amgen has denied a request by the FDA to voluntarily withdraw its rare disease drug Tavneos from the market, the company said Tuesday as it presented quarterly financial results.
Amgen explained that the U.S. regulator issued its request Jan. 16 and that, “following FDA regulatory process,” the company informed the agency Jan. 28 of its intention to keep the drug on the market. The California drugmaker added that it is evaluating next steps with the agency to “determine a path forward.”
The news comes days after the European Medicines Agency said it was re-reviewing Tavneos because of concerns about the integrity of the data in the drug’s pivotal trial.
Last month, FDA told Amgen that it was questioning the process followed by the original developer of the drug, ChemoCentryx, to re-adjudicate primary endpoint results for nine of the 331 patients in its phase 3 study. The FDA also is reviewing the risk-benefit profile of Tavneos, which can, in rare cases, cause hepatotoxicity, Amgen added.
“Amgen is not aware of any issue with the underlying patient data from the ChemoCentryx clinical trial,” the company wrote in its fourth-quarter earnings release. "And after review of the relevant clinical data and years of real-world evidence, Amgen is confident that Tavneos demonstrates effectiveness and a favorable benefit–risk profile."
Amgen’s commercial operations chief Murdo Gordon emphasized during a conference call that there are “limited therapeutic options” for patients on Tavneos, which treats antineutrophil cytoplasmic antibody-associated vasculitis, which causes inflammation of the blood vessels.
The company offered little else on Tavneos during its presentation and call.
“We’re in discussions with the FDA, and we’ll answer questions as we talk with them,” Jay Bradner, Amgen’s R&D chief, said Tuesday.
Tavneos was approved in the U.S. in 2021, and Europe signed off on the complement inhibitor in 2022. That same year, Amgen bought out ChemoCentryx for $3.7 billion.
Concerns about the trial have been mounting since 2021, when the FDA flagged them ahead of a preapproval advisory committee meeting. Even though Tavneos eventually got its FDA nod—with a narrower label than anticipated—investors filed a lawsuit in 2022 alleging that ChemoCentryx knew about the FDA’s concerns but downplayed them.
As the legal feud progressed, additional evidence emerged last year pointing to a larger data integrity issue in the trial. Despite this, Amgen was victorious defending itself in a lawsuit that was dismissed six months ago as a California judge agreed with the company’s argument that the FDA’s approval of a drug “precludes a securities fraud plaintiff from showing that a defendant’s favorable interpretation of the drug’s clinical trial data was fraudulent.”
Amgen has one of the most diverse and deep portfolios in the industry, counting 14 blockbuster drugs in 2025. And, even though CEO Bob Bradway called Tavneos “a very small product in our portfolio relative to the other things we’ve got going on,” losing it would be blow as its sales are scaling up rapidly. In 2025, Tavneos generated $459 million, which was a 62% year-over-year increase, “driven by strong volume growth,” according to Gordon.
Amgen was much more anxious to discuss the trajectory of another of its rare disease treatments, Uplizna, which gained two label expansions in 2025. One is to treat certain patients with generalized myasthenia gravis (gMG); the other was for those with immunoglobulin G4-related disease (IgG4-RD). The company estimated Tuesday that the U.S. patient population in the new IgG4-RD indication is 35,000, with potential to grow.
Amgen also said it expects this year to kick off two phase 3 trials of Uplizna—one for patients with autoimmune hepatitis and another for those with chronic inflammatory demyelinating polyneuropathy.
Uplizna sales were up 73% in 2025 to $655 million, “reflecting growing patient demand across all three approved indications,” Gordon said. The drug hit the market in 2020 as a treatment for original neuromyelitis optica spectrum disorder.
“Uplizna’s unique anti-CD19 (mechanism of action), which provides efficacy and dosing advantages vs. [FcRn inhibitors], plays into a gMG market that is currently evenly split between biologics-naïve and switchers,” analysts from Citi wrote.
Amgen’s overall revenue came in at $36.7 billion in 2025, which was an increase of 10%. The company is guiding to a smaller revenue increase in 2026, pegging sales at between $37 billion and $38.4 billion, with Chief Financial Officer Peter Griffith calling it a “springboard year for future growth” as the company rides out biosimilar competition for denosumab (osteoporosis treatments Prolia and Xgeva).
“[Amgen’s] rare disease, oncology, and biosimilars portfolios could also help offset further acceleration of denosumab erosion on deck for this year,” Citi wrote, estimating a 30% year-over-year decline in sales of Prolia and Xgeva. “Specifically, Uplizna might be an underappreciated asset within the Horizon portfolio.”