What happened
Shares of ChemoCentryx (NASDAQ: CCXI) suffered an ugly 79% plunge in May, according to data provided by S&P Global Market Intelligence, after a Food and Drug Administration advisory committee offered up a split opinion on the efficacy of avacopan, the biotech's treatment for antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV).

So what
The panel generally leaned in favor of the treatment, voting 10-8 in support of avacopan's safety profile and its benefit-risk profile in treating adult AAV patients, but it split 9-9 on whether the efficacy data supported approving avacopan for treating them.