Amgen NASDAQ:AMGN is facing fresh pressure after the New England Journal of Medicine retracted the 2021 clinical trial used to support approval of Tavneos, its pill for ANCA-associated vasculitis. The journal said two study authors requested the retraction after an FDA investigation found results from nine patients were changed after the study database had been finalized, while some researchers had been unblinded. NEJM said those details were not disclosed in the article and were inconsistent with proper research conduct, raising new questions over the drug's continued sales.
The FDA has alleged that the original data did not show a statistically significant remission difference between Tavneos and other available treatments, but later changes made the drug appear more effective. The agency said in April that new information surfaced more than three years after approval and proposed withdrawing Tavneos from the market. European regulators have also proposed pulling the drug based on the same study, while CSL, which sells Tavneos in Europe under a license from ChemoCentryx, has said the medicine will not be offered to new patients.
Amgen acquired ChemoCentryx for $3.7 billion in 2022 and has continued selling Tavneos in the US, arguing that the drug's benefits outweigh its risks while requesting a hearing to contest the FDA's action. Tavneos generated $459 million last year, while Wall Street analysts had expected $526 million in sales in 2026. Amgen said it takes scientific integrity seriously and has engaged independent academic researchers to reanalyze the data, with plans to share the results with the FDA and submit them for publication. Amgen shares pared earlier gains of as much as 1.3% Monday and were up 0.3% at 3:36 p.m. in New York.