ChemoCentryx, acquired by Amgen for $3.7 billion in 2022, is facing investor allegations that it withheld and altered trial data related to Tavneos (avacopan), a drug developed to treat antineutrophil cytoplasmic antibody-associated vasculitis (AAV). The claims are part of a lawsuit initially filed in 2021 against ChemoCentryx and its then-CEO, Thomas Schall.
The case alleges that ChemoCentryx misled investors during the FDA application process for Tavneos and in communications concerning the underlying phase 3 Advocate trial. From late 2019 to early 2021, the company’s stock rose following positive data from the trial, during which time Schall sold approximately $40 million in company shares. However, safety and efficacy concerns raised by the FDA later resulted in amendments to the company’s application and ultimately a narrower label than originally sought. ChemoCentryx was later acquired by Amgen at a value below its stock price peak.
According to an amended complaint filed in 2022, investors claim that ChemoCentryx was aware of the FDA’s concerns but publicly characterized its engagement with the agency as unproblematic. Plaintiffs further allege that the company promoted Tavneos as a safer alternative to steroids despite the Advocate trial involving off-protocol steroid use in the Tavneos group and raising questions about liver toxicity.
In newly submitted materials opposing a motion for summary judgment, plaintiffs have introduced additional claims. They state that Pirow Bekker, M.D., Ph.D., then the clinical lead for Tavneos and a former chief medical officer of ChemoCentryx, changed the classification of five patients from nonresponders to responders after learning that the trial had not met its superiority goal at one year. These changes reportedly occurred after the trial’s database had already been locked, a point which typically marks the end of allowable data modifications.
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he plaintiffs claim ChemoCentryx later supplied regulators with a revised database lock date that did not correspond to the actual lock date. They also argue that the changes lacked scientific justification, citing the views of several experts. In response, Steven Weisman, Ph.D., global president of clinical and regulatory at Lumanity, stated that the reclassification was consistent with a prespecified statistical analysis plan.
He said that although Bekker had been unblinded during the re-evaluation, the final determinations were made by an adjudicator who remained blinded. “[T]he re-adjudication of the patients at issue was performed by the still-blinded Adjudication Committee Chair in a manner consistent with the Adjudication Committee Charter,” Weisman wrote in an expert report filed in June.
According to the plaintiffs, the data monitoring committee for the Advocate trial repeatedly warned ChemoCentryx that its public communications understated the liver toxicity risks associated with Tavneos. In a March 2021 letter addressed to Schall, the committee requested that he “[i]mmediately submit a letter to the editor of the [NEJM] clarifying the hepatotoxicity risks,” and that prior correspondence and meeting records be shared with the FDA. Plaintiffs allege that Schall did not act on the committee’s request.
Concerns about liver toxicity became public when the FDA disclosed that a patient in the Tavneos group experienced toxicity that met Hy’s Law criteria. Liver toxicity is listed first in the “warnings and precautions” section of the drug’s FDA label.
Internally, Cass Kelleher, M.D., then serving as chief medical officer, stated that she urged Schall to publicly acknowledge the liver risk. In her deposition, Kelleher said Schall told her she was being too vocal and to “stop talking” about the safety signal. Kelleher was also not included among the authors of the 2021 New England Journal of Medicine paper and testified that she was unaware of its publication until after it was released. “Originally, this paper was going to be authored by me, and I thought it was dead,” she said, according to a court transcript, “And I didn’t even know there was a paper until somebody called and said it’s been published.”
Weisman argued that the FDA’s approval of Tavneos supports the conclusion that the drug’s safety profile was acceptable. He said the agency had full access to the data changes and maintained that the approval outcome undermines the assertion that liver-related adverse events had a significant impact on the overall benefit-risk evaluation.
After the amended complaint was filed, the court dismissed some allegations but upheld class certification. In May of the following year, RA Capital filed similar lawsuits in the California Superior Court in Ventura County and the U.S. Northern District Court of California. Amgen has not commented publicly on the case.
