Earlier this year, when the FDA asked Amgen to pull its rare disease drug Tabneos from the market, the California drugmaker rejected the request. Now, U.S. regulators are applying even more pressure.
The FDA’s Center for Drug Evaluation and Research (CDER) has proposed rescinding approval of Amgen’s oral drug, citing new information showing that data was “manipulated” to facilitate the green light for Amgen’s oral drug.
In the letter (PDF), CDER also singled out Amgen subsidiary Chemocentrics, saying Tavneos is ineffective and that its application for approval as a treatment for ANCA-related vasculitis contains false statements. Additionally, CDER noted cases of severe drug-induced liver injury (DILI) and said it was “increasingly concerned about the safety of Tabneos.”
The FDA said Amgen’s options are to remove the drug from the market or request a hearing.
An Amgen spokesperson said in an email that the company is considering its next steps.
“We remain confident that Tabneos is a safe and effective medicine, supported by years of clinical data and real-world evidence,” the spokesperson wrote. “Our view of the benefit and risk profile of Tabneos differs from that of the authorities.”
In its letter, CDER explained that more than three years after Tavneos’ approval, it realized that data from a pivotal trial had been “manipulated” to make the drug appear to be effective, “even though the original analysis did not support that conclusion.”
“The applicant also failed to disclose the original analysis results to FDA, in violation of FDA regulations,” it said in a release posted on its website. “CDER can no longer conclude that there is, or ever was, valid demonstration that Tavneos is effective in its approved use.”
These allegations revolve around the development of Chemocentrix before it was approved in October 2021. Ten months later, Amgen acquired Chemocentrics for $3.7 billion.
Concerns about the trial have been growing for years, with the FDA issuing a warning ahead of a 2021 preapproval advisory committee meeting. Even though Tabneos won FDA approval with a narrower-than-expected label, investors filed a lawsuit in 2022, accusing Chemocentrics of knowing and downplaying the FDA’s concerns.
As the legal battle progressed, additional evidence emerged last year pointing to larger data integrity issues at trial. Nevertheless, Amgen successfully defended itself in an investor lawsuit that was dismissed eight months ago because a California judge agreed with the company’s argument that the FDA’s approval of the drug “prevents securities fraud plaintiffs from showing that defendants’ favorable interpretation of the drug’s clinical trial data is fraudulent.”
Just last month, the FDA warned of the risk of liver damage associated with the use of Tabneos. Since approval, through October 2024, 76 cases of DILI with “reasonable evidence” of a causal relationship to Tabneos have been reported to the FDA Adverse Event Reporting System (FAERS). Nearly all reported cases had severe outcomes, with 54 patients hospitalized and eight deaths, according to the FDA.
This 10 mg tablet is used in combination with glucocorticoids and other standard treatments to treat anti-neutrophil cytoplasmic antibody-associated (ANCA) vasculitis, a rare autoimmune disease. This vasculitis damages small blood vessels and eventually leads to organ failure, especially the kidneys.
An Amgen spokesperson said the company is “putting patient needs and support at the forefront” in determining its future course.
“ANCA-associated vasculitis is a rare, serious and potentially life-threatening disease, and the availability of treatments is important to patients,” the spokesperson added.
Amgen has the most diverse and deep portfolio in the industry, with 14 blockbuster drugs in 2025. But the company’s sales are growing rapidly, so losing Tabneos would be a blow. It generated $459 million in 2025, an increase of 62% from 2024.
