On May 4, 2021, the U.S. Food and Drug Administration released a “Briefing Document” concerning ChemoCentryx’s drug candidate avacopan, which is in development for the treatment of adult patients with anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis. To support its New Drug Application for avacopan, ChemoCentryx relied primarily upon its Phase III ADVOCATE study. In the Briefing Document, the FDA wrote that “[c]omplexities of the study design . . . raise questions about the interpretability of the data to define a clinically meaningful benefit of avacopan and its role in the management of” ANCA vasculitis. The FDA further wrote that it had “identified several areas of concern, raising uncertainty about the interpretability of the data and the clinical meaningfulness of these results . . . .” On this news, shares of ChemoCentryx stock fell approximately 45% in one day, after plummeting by over 60% during intraday trading on May 4, 2021.