Amgen Shares Plunge on Regulator Pressure for Tavneos

Amgen's shares have fallen by 6.8% due to renewed concerns about the regulatory pressure on its drug Tavneos. The U.K. medicines regulator suspended use of avacopan, previously marketed as Tavneos, for new patients starting September 1, 2026. This setback adds to existing overhang in the US, where the FDA has proposed withdrawing approval of Tavneos.

The U.K. review cited concerns about efficacy due to a pivotal study that could no longer be relied upon. The decision raises fears that other markets may also take a tougher stance on Tavneos. Amgen is still defending the drug and engaging with regulators, but investors are reassessing regulatory risk.

The U.S. FDA had previously proposed withdrawing approval in April 2026 due to questions about effectiveness and alleged untrue statements of material fact in the original application. The latest development could lead to a loss of value for Tavneos across multiple regions.