Stock-price weakness that has beset Chemocentryx Inc. since early March – likely based on jitters ahead of the FDA advisory panel for avacopan slated for May 6 – became an outright tumble when Wall Street got a gander at briefing documents related to the meeting. Shares of the San Carlos, Calif-based firm (NASDAQ:CCXI) closed at $22.19, down $26.63, or 45%, as company backers sifted paperwork on the complement C5a receptor inhibitor for anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis. The compound has been assigned a PDUFA date of July 7.