On Tuesday, Health Canada issued a circular directing physicians to cease prescribing Tavneos (avacopan) to new patients, citing "significant concerns" with the pivotal clinical trial that supported the drug's approval for ANCA-associated vasculitis, a rare autoimmune condition affecting 10 to 20 persons per million annually in Western countries, primarily the elderly.
Retracted Study and FDA Investigation
The study, published in the New England Journal of Medicine (NEJM) in February 2021, involved 331 patients from 143 hospitals globally. It was formally retracted on June 29, 2026, after the two academic authors requested withdrawal. The retraction notice stated that an ongoing U.S. Food and Drug Administration (FDA) investigation revealed that primary end-point assessments in nine patients were re-adjudicated after database lock and trial unblinding, without the authors' knowledge, constituting improper research conduct.
Data Tampering Uncovered
The FDA had previously warned in April 2026 that it was considering removing avacopan from the market. The misconduct was uncovered through a securities-fraud lawsuit against ChemoCentryx, the original patent-holder, which hired a forensic investigator. The investigation found that on November 5, 2019, the trial data was locked and unblinded. Two ChemoCentryx employees then accessed the data, realized the drug's superiority had not reached statistical significance, and according to emails quoted in the FDA notice, one wrote, "We cannot afford to miss a superiority outcome here." They broke the database lock, re-adjudicated several patients' outcomes favorably, and re-locked the data to achieve significance.
Impact and Regulatory Response
Health Canada's directive follows the NEJM retraction and FDA actions. Amgen, which acquired ChemoCentryx after approval, has been notified. The drug's effectiveness was already questioned by some critics due to statistical concerns. The case underscores the vulnerability of drug approval processes to data manipulation and the importance of post-market surveillance.
