EMA Initiates Data Integrity Review of Amgen's Tavneos Following Concerns Over Pivotal ADVOCATE Study
Key Insights
The European Medicines Agency has launched a comprehensive review of Tavneos (avacopan) following emerging information that raises questions about data integrity in the pivotal ADVOCATE study that supported the drug's EU approval.
The concerns relate to how data from the 331-patient ADVOCATE trial was handled before authorization, potentially impacting findings on the complement C5 (search) inhibitor's effectiveness in treating rare autoimmune vasculitis conditions.
The EMA will assess whether the data integrity issues affect Tavneos' benefit-risk balance and may recommend maintaining, amending, suspending, or revoking the marketing authorization.
The European Medicines Agency (EMA) has initiated a comprehensive review of Tavneos (avacopan), Amgen's oral complement C5 (search) inhibitor, following emerging information that raises questions about data integrity in the pivotal ADVOCATE study that supported the drug's European Union approval in 2022.
The EMA's human medicines committee (CHMP) launched the review at the request of the European Commission under Article 20 of Regulation (EC) No 726/2004. The regulatory concerns center on how data from the ADVOCATE study was handled before Tavneos received authorization, which may have impacted findings on the medicine's effectiveness in treating severe, active granulomatosis with polyangiitis (search) (GPA) or microscopic polyangiitis (search) (MPA).
ADVOCATE Study Under Scrutiny
The ADVOCATE trial, which included 331 patients with GPA or MPA, served as the main study supporting Tavneos' marketing authorization in the European Union. In this pivotal study, Tavneos was compared with high-dose corticosteroids, both administered in addition to standard treatment consisting of either rituximab or a regimen of cyclophosphamide followed by azathioprine.
Based on data from the ADVOCATE study, Tavneos was found to be at least as effective as high-dose corticosteroids in inducing remission in patients with GPA or MPA and demonstrated superior long-term remission rates. However, the EMA now states that concerns "relate to how the data for the ADVOCATE study was handled before Tavneos was authorised, which may have impacted the findings on the medicine's effectiveness."
Regulatory Path and Commercial Success
Tavneos was originally developed by ChemoCentryx (search), which Amgen acquired for $3.7 billion in 2022. The drug first received approval in the United States for the same two indications in 2021, becoming the first orally-active drug that targets the complement C5 (search) receptor. The US approval came despite earlier FDA skepticism about the phase 3 trial design and an advisory committee meeting that was evenly split on whether the efficacy data supported approval.
Despite regulatory challenges, Tavneos has emerged as one of Amgen's fastest-growing products. US sales more than doubled to $283 million in 2024 and increased another 49% to $301 million in the first nine months of 2025. In Europe, CSL Vifor (search) holds licensing rights for the drug under an agreement with ChemoCentryx (search) that predated Amgen's acquisition, though specific European sales figures are not disclosed.
Treatment Landscape for Rare Autoimmune Conditions
Prior to Tavneos' approval, patients with GPA and MPA were typically treated with the anti-CD20 (search) antibody rituximab combined with corticosteroids, a regimen that can cause serious side effects when administered over prolonged periods. GSK's IL-5 (search) inhibitor Nucala (mepolizumab) has also received approval in some markets, including EU member states and the US, as an add-on treatment for adults with GPA associated with high levels of blood eosinophils.
Regulatory Review Process
The EMA will now conduct a comprehensive review of all available data to assess whether the emerging information regarding data integrity impacts the balance of benefits and risks of Tavneos. Following this assessment, the agency will issue a recommendation on whether the marketing authorization in the EU should be maintained, amended, suspended, or revoked.
The CHMP, responsible for questions concerning medicines for human use, will adopt the agency's opinion. This opinion will then be forwarded to the European Commission, which will issue a final legally binding decision applicable in all EU member states. CSL Vifor (search), which holds European licensing rights for Tavneos, has not yet commented on the development.