Health Canada is reviewing the evidence supporting the drug TAVNEOS after significant concerns were raised about the integrity of data from the main clinical trial that led to the medication’s approval in Canada.

The regulator issued a risk communication Tuesday, advising health-care professionals not to start new patients on TAVNEOS while it assesses whether the drug’s benefits continue to outweigh its risks.

Health Canada said the concerns involve the Phase 3 ADVOCATE trial. The primary study used to support the April 2022 authorization of TAVNEOS (avacopan) for adults with severe active anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis.

ANCA-associated vasculitis is a group of rare autoimmune diseases that cause inflammation of blood vessels, including granulomatosis with polyangiitis and microscopic polyangiitis. TAVNEOS is approved for use alongside standard therapy, including glucocorticoids, and is not intended to be used on its own.

According to Health Canada, new information has raised “significant concerns” about how data from the ADVOCATE trial was handled before the drug was authorized, creating uncertainty about the reliability of the evidence supporting its effectiveness.

The concerns also led the New England Journal of Medicine to retract publication of the ADVOCATE trial on June 29.

While the review is underway, Health Canada is advising health-care professionals not to initiate treatment with TAVNEOS in new patients. It is also recommending that physicians contact and monitor patients already receiving the drug and determine whether continuing treatment remains appropriate.

Health Canada said patients currently taking TAVNEOS should not stop treatment without first speaking with their health-care provider. Instead, they should discuss whether continuing the medication or switching to another treatment is appropriate.

The regulator emphasized that its review is focused on questions surrounding the reliability of the clinical trial data used to support the drug’s effectiveness. It said it is assessing whether those concerns affect the product’s overall benefit-risk profile in Canada.

Health Canada said it is notifying health-care professionals through its MedEffect system and the Healthy Canadians recalls and safety alerts database. It is also encouraging health-care professionals and patients to report any serious or unexpected adverse reactions associated with TAVNEOS.