Amgen (AMGN) faces mounting pressure over its rare disease drug Tavneos after European regulators published detailed findings underpinning their decision to revoke its marketing authorisation.
The European Commission formally confirmed last week that Tavneos would be withdrawn from the EU market, adopting a June recommendation from the European Medicines Agency’s Committee for Medicinal Products for Human Use, known as the CHMP.
Tavneos was originally developed by ChemoCentryx to treat the two most common forms of ANCA-associated vasculitis, a serious autoimmune disorder affecting blood vessels throughout the body.
Amgen acquired ChemoCentryx in 2022 for $3.7 billion, inheriting both the drug’s commercial prospects and the growing regulatory difficulties now threatening its future.
In Europe, Tavneos’ marketing rights sat with CSL Vifor, which confirmed the European Commission’s final decision and said it was “committed to implementing it in full.”
The CHMP’s published documents allege that the pivotal phase 3 Advocate study, which secured Tavneos its original approvals, contained “serious breaches to good clinical practice principles in the handling of primary endpoint data.”
Regulators specifically allege that study sponsor personnel accessed unblinded efficacy data after an initial database lock, learning that superiority had not been demonstrated at the critical 52-week point in the trial.
The CHMP further alleged that nine patients were subsequently re-adjudicated “based on knowledge of treatment outcomes, after which the primary analysis was rerun resulting in a change from a non-significant to a statistically significant result for superiority at week 52.”
The regulator said it was not persuaded by the study sponsor’s justification for the re-adjudication, and additionally raised safety concerns around fatal cases of drug-induced liver injury and vanishing bile duct syndrome reported in patients since authorisation.
“On balance,” the CHMP wrote, “considering that the pivotal study supporting the marketing authorization is considered as not reliable due to the serious GCP breach, it is concluded that there is no longer demonstration of benefit outweighing the risks of Tavneos, in particular the serious hepatic risks.”
Amgen pushed back firmly, stating it disagreed with the EMA’s decision and was “deeply concerned about the impact this decision may have on rare disease patients.”
A company spokesperson argued that the EMA’s interpretation “fails to appropriately recognize the totality of evidence supporting the effectiveness and favorable benefit-risk profile of Tavneos,” citing real-world studies and secondary endpoint findings.
Amgen’s statement noted that ANCA-associated vasculitis “can cause irreversible organ damage” and warned that removing Tavneos “further limits treatment options for this community.”
The battle is not confined to Europe, as Amgen is also fighting to retain Tavneos’ position in the United States after the FDA issued a market withdrawal request earlier this year.
Late last month, Amgen submitted a data and analysis package to the FDA that includes a third-party re-evaluation of the Advocate study by the Duke Clinical Research Institute, alongside real-world evidence and patient testimonials.