Why Exelixis Stock Fell Last Week

On May 11, Exelixis’s (EXEL) closing price was $19.55, almost 12.9% lower than its closing price on May 4. This fall was mainly attributable to unfavorable results released from its Phase 3 IMblaze370 study comparing a combination regimen of Cotellic (cobimetinib) with Roche Holdings’ (RHHBY) Tecentriq (atezolizumab) compared to Bayer’s Stivarga in locally advanced or metastatic colorectal cancer indications. Exelixis and Roche Holdings’ investigational combination regimen failed to demonstrate a statistically significant improvement in the primary end point of overall survival compared to Stivarga in difficult-to-treat patients who had witnessed disease progression or had been unable to tolerate at least two chemotherapy treatments.