Shares of ChemoCentryx ($CCXI) tanked this morning after the biotech released weak interim results for its mid-stage study on a new drug for diabetic nephropathy. The company says the chemokine receptor CCX140 spurred a significant reduction in proteinuria after 12 weeks of therapy, spurring some confident remarks from executives. But some analysts said the drug was not clearly better than a placebo, prompting a 23% plunge in the stock price. A few weeks ago another one of the Mountain View, CA-based biotech's drugs outlicensed to GlaxoSmithKline ($GSK) for Crohn's disease failed the first of four late-stage studies. Release