Stock Markets September 1, 2026 11:57 AM

UK Regulator Halts New Prescriptions of Amgen's Tavneos Citing Unreliable Trial Data

MHRA suspends sales to new patients and sets revocation date after concluding the pivotal study cannot verify benefit-risk balance

By Ajmal Hussain
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AMGN CSL

Britain’s Medicines and Healthcare products Regulatory Agency (MHRA) has suspended the use and sale of Tavneos to new patients after determining that the main clinical trial supporting its approval contained unreliable data. CSL Vifor markets the drug in the UK; Amgen holds U.S. rights. The MHRA will revoke the product’s UK approval on March 1, 2027, while existing patients may continue treatment for six months under medical supervision.

UK Regulator Halts New Prescriptions of Amgen's Tavneos Citing Unreliable Trial Data
AMGN CSL
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Key Points

  • The MHRA has suspended the use and sale of Tavneos to new patients after finding the main trial data unreliable, undermining proof of effectiveness and benefit-risk balance.
  • CSL Vifor markets the drug in Britain (Avacopan Vifor); Amgen holds U.S. rights following its $3.7 billion acquisition of ChemoCentryx in 2022.
  • Existing patients may continue treatment for six months while clinicians evaluate alternatives; the MHRA plans to revoke UK approval on March 1, 2027.

Regulatory action

Britain’s Medicines and Healthcare products Regulatory Agency (MHRA) has suspended the use and sale of Tavneos to new patients, concluding that the principal study underpinning the medicine’s approval contained unreliable data. The agency said this flaw means the trial can no longer demonstrate the drug’s effectiveness or show that its benefits outweigh its risks.

Product and prescribing context

Marketed in the UK by CSL Vifor under the name Avacopan Vifor, the medicine is prescribed alongside other treatments for severe autoimmune conditions that produce inflammation in small blood vessels and can lead to kidney and lung damage. The MHRA’s suspension applies specifically to new patients; it does not immediately stop ongoing therapy.

Transition and patient guidance

Patients currently receiving the drug are able to continue treatment for a six-month period while clinicians assess alternative therapies. The regulator explicitly advised patients not to discontinue their medication without consulting a specialist, underscoring the need for clinician-led transition plans.

Regulatory timeline

Alongside the suspension for new patients, the MHRA has announced plans to revoke the UK marketing authorisation for the drug on March 1, 2027. The agency linked that decision to the unreliability of key trial data that originally supported approval.

Corporate positions and rights

Amgen acquired the developer, ChemoCentryx, for $3.7 billion in 2022. Amgen retains rights to the drug in the United States, while CSL Vifor holds commercial rights in selected markets outside the U.S., including the UK. An Amgen spokesperson said the company disagrees with the MHRA’s decision and expressed deep concern about the potential effect on patients with rare diseases.

Amgen also stated that the regulator did not adequately weigh evidence from clinical trials and more than 20 published real-world studies that support the medicine.

Broader regulatory context

Earlier, the European Commission revoked approval for the drug in August after regulators determined that key trial data were unreliable. The MHRA action in the UK follows that European decision and sets a specified revocation date for the UK market.

Risks

  • Regulatory revocation - The planned March 1, 2027 revocation introduces regulatory uncertainty for commercial rights holders and could affect revenues in impacted markets - sector: pharmaceuticals/biotech.
  • Patient care disruption - Patients currently on the medicine will need clinical reassessment and may face changes in therapy, creating potential strain on clinical services - sector: healthcare.
  • Reputational and evidentiary disputes - Disagreement between the manufacturer and regulator over the interpretation of trial and real-world evidence could prolong legal, regulatory, or commercial disputes - sector: pharmaceuticals/biotech.

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