Australia's medicines regulator announces a review but allows access to continue, while manufacturer Amgen mounts a fresh defence of the vasculitis treatment in the US.
Australian rheumatologists are being urged to continue carefully weighing the risks and benefits of avacopan as the Therapeutic Goods Administration launches a safety review amid escalating international concerns over the medicine.
The TGA this week confirmed it is reviewing the benefit-risk profile of avacopan (Tavneos), which is approved in Australia for use alongside standard therapy in adults with severe active ANCA-associated vasculitis, including granulomatosis with polyangiitis and microscopic polyangiitis.
The regulator said no changes have yet been made to the medicine’s Australian registration or prescribing information while the review is underway.
“The TGA is reviewing new information that has raised concerns regarding the integrity and reliability of the clinical trial data that supported the approval of Tavneos (avacopan) in Australia,” the regulator said in a safety update statement.
“The purpose of this review is to assess the efficacy and safety of Tavneos (avacopan) in light of this new information. The TGA is also aware of the recent media and international regulatory action in relation to this matter.
“The TGA will provide further information, including any updated advice for healthcare professionals and patients when available.”
The Australian review follows an extraordinary series of regulatory developments overseas, where the US Food and Drug Administration proposed withdrawing approval of the drug after concluding it could no longer establish that Tavneos had demonstrated effectiveness for its approved indication.
In Australia, however, the TGA has stressed that patients should not stop treatment without consulting their treating specialist and that clinicians should continue making prescribing decisions on an individual patient basis while the review proceeds.
The regulator is also encouraging healthcare professionals to report suspected adverse events to support ongoing pharmacovigilance.
The development places Australian rheumatologists in an unusual position. Avacopan was welcomed as the first oral complement C5a receptor inhibitor for ANCA-associated vasculitis, offering the possibility of reducing cumulative glucocorticoid exposure in a disease where steroid toxicity remains a major challenge.
Since its approval, the drug has become an important steroid-sparing option for selected patients with severe disease.
International scrutiny intensified earlier this year after regulators began examining questions surrounding the integrity of data supporting the pivotal clinical trial and the drug’s effectiveness.
As reported by Rheumatology Republic in early July, the pivotal trial underpinning avacopan’s place in ANCA-associated vasculitis has been retracted after an FDA investigation identified undisclosed changes to efficacy endpoint assessments following trial unblinding.
CSL issued its own open letter in response to the issue.
The New England Journal of Medicine announced in a statement it had formally retracted the 2021 ADVOCATE trial after the paper’s two academic authors requested its withdrawal.
According to the journal, an ongoing investigation by the US Food and Drug Administration found that primary endpoint assessments in nine patients were readjudicated after the trial database had been locked and treatment allocation unblinded, without the knowledge of the academic investigators.
“This was not disclosed in the article and is inconsistent with proper research conduct. The editors therefore retract the article,” the journal’s statement said.
The retraction came just days after the European Medicines Agency’s Committee for Medicinal Products for Human Use recommended revoking the European marketing authorisation for avacopan (Tavneos), concluding an Article 20 review initiated because of concerns about data handling during the ADVOCATE study.
The recommendation still needs to be confirmed by the European Commission before the authorisation is revoked in the European Union.
Similarly, the FDA’s proposed withdrawal remains subject to a formal hearing process and is not a final regulatory decision.
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Amgen, which acquired the drug through its purchase of ChemoCentryx, is vigorously contesting the recommendations.
Avacopan was developed by ChemoCentryx and is commercialised outside the US and in selected countries including Australia by CSL, its affiliates, and partners pursuant to a collaboration and license agreement between Vifor Fresenius Medical Care Renal Pharma Ltd and ChemoCentryx. Amgen acquired ChemoCentryx in 2022.
Last month the company submitted new analyses and additional evidence to the agency in an attempt to preserve US approval, arguing the totality of evidence continues to support a favourable benefit-risk profile for patients with ANCA-associated vasculitis.
In an extensive statement published on its website, Amgen acknowledged the “heightened focus” on avacopan.
“On July 23, 2026, Amgen submitted data and analyses to the US Food and Drug Administration (FDA) in support of its request for a hearing on Tavneos, with the goal of preserving access to the medicine in the United States,” the statement said.
“Amgen strongly disagrees with the FDA’s proposal to withdraw Tavneos from the US market.
“Our submission includes extensive scientific analyses demonstrating that Tavneos meets the statutory standard for substantial evidence of effectiveness.
“Based on the totality of the evidence, we continue to believe Tavneos has a favourable benefit-risk profile and remains an important treatment option for appropriate patients.”
Amgen went on to say it welcomed “the opportunity for a science- and patient-focused engagement with the FDA, where we will present the totality of scientific evidence supporting Tavneos, including its positive benefit-risk profile, the seriousness of AAV, the limitations and burden of existing treatment approaches, and the importance of preserving treatment options for patients”.
“Removing Tavneos from the market would significantly narrow the choices available to physicians and patients and would leave some patients more dependent on treatment regimens that carry their own serious and well-established burdens, including prolonged steroid exposure,” the statement said.
The outcome is expected to have significant implications for patients with this rare but potentially life-threatening autoimmune vasculitis, particularly given the limited number of targeted treatment options currently available.
However, for now, for Australian clinicians, the immediate message remains unchanged.
The TGA has not advised discontinuing treatment or restricting prescribing while its assessment continues, instead recommending that specialists discuss the potential benefits and risks with individual patients and continue monitoring for adverse events as part of routine care.
“Consumers and healthcare professionals are encouraged to report any suspected adverse events associated with Tavneos (avacopan) to the TGA,” the regulator said.
