Earlier this year, when the FDA asked Amgen to pull its rare disease drug Tavneos from the market, the California drugmaker denied the request. Now, the U.S. regulator is applying more pressure.
The FDA’s Center for Drug Evaluation and Research (CDER) has proposed to withdraw the approval of Amgen's oral medicine, saying new information indicates the data was "manipulated" to facilitate its green light.
CDER said in a letter (PDF), which also called out Amgen’s subsidiary ChemoCentryx, that Tavneos is not effective and that its application for approval to treat ANCA-associated vasculitis included untrue statements. In addition, CDER noted that it is “increasingly concerned about the safety of Tavneos,” pointing to cases of serious drug-induced liver injury (DILI).
The FDA said that Amgen’s options are to pull the drug from the market or request a hearing.
The company is evaluating its next steps, an Amgen spokesperson said in an email.
“We remain confident in Tavneos as a safe and effective medicine, supported by years of clinical data and real-world evidence,” the spokesperson wrote. “Our perspective on the benefit-risk profile of Tavneos differs from the Agency’s.”
CDER explained in its letter that it became aware more than three years after the approval of Tavneos that data from the pivotal trial was “manipulated” to make the drug look effective “when the original analysis did not support that conclusion.”
“The applicant also did not disclose the original analysis to FDA, in violation of FDA regulations,” it wrote in a release posted to its website. “CDER can no longer conclude that there is, or has ever been, a valid demonstration that Tavneos is effective for its approved use.”
These allegations surround ChemoCentryx’s development of the drug before it was approved in October 2021. Ten months later, Amgen bought out ChemoCentryx for $3.7 billion.
Concerns about the trial have been mounting for years, with the FDA flagging them ahead of a preapproval advisory committee meeting back in 2021. Even though Tavneos won 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 its investor lawsuit that was dismissed eight 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.”
Just last month, the FDA warned of the risk of liver injury that could accompany use of Tavneos. Since its approval and through October 2024, 76 cases of DILI with “reasonable evidence” of a causal association to Tavneos were reported to the FDA Adverse Event Reporting System (FAERS). Nearly all of the reported cases resulted in a serious outcome, including hospitalization in 54 patients and death in eight, the FDA said.
The 10 mg pill is used with glucocorticoids and other standard-of-care medications to treat the rare autoimmune disease anti-neutrophil cytoplasmic antibody-associated (ANCA) vasculitis, which causes damage to small blood vessels and eventually leads to organ failure, especially in the kidneys.
As it decides how to proceed, Amgen’s spokesperson said that the company is “keeping patient need and support at the forefront.”
“ANCA-associated vasculitis is a serious and potentially life-threatening rare disease, and the availability of treatments matters for patients,” the spokesperson added.
Amgen has one of the most diverse and deep portfolios in the industry, counting 14 blockbuster drugs in 2025. But losing Tavneos would be blow as its sales are scaling up rapidly. In 2025, it generated $459 million, which was a 62% increase from 2024.