Good news from the lab sparked a mini-rally in Vertex Pharmaceuticals (VRTX 2.35%) stock on Tuesday. The biotech's shares closed the trading session more than 2% higher in price, which was good enough to top the flat-lining S&P 500 index. One of the company's investigational drugs is showing decent promise in a clinical trial. Pain drug meets primary endpoint in study Vertex announced that its VX-548, a non-opioid medication aimed at treating moderate to severe acute pain, met its primary endpoint in a phas ...