The future of a “revolutionary” treatment for a form of vasculitis is in doubt, after international drug watchdogs warned of dozens of linked deaths, and The New England Journal of Medicine retracted the phase III study.

While the TGA has said little so far, an immunologist says it is possible that around 1000 Australian patients will have to be moved to corticosteroid treatment.

Avacopan, used for serious antineutrophil cytoplasmic autoantibody-associated vasculitis (AAV), was approved in Australia in 2023 as a first-in-class inhibitor of the complement 5a protein, which is a factor in the pathogenesis of AAV.

But in March this year, the US Food and Drug Administration (FDA) said that it had identified 76 cases of drug-induced liver injury causally linked to avacopan since October 2024.