In drug development, solid performance in large-scale clinical trials is crucial.There was some good news in the clinical sphere for Gilead Sciences (GILD 2.74%) on Thursday, and this drove its stock price up by almost 3% that trading session. A late-stage clinical trial of an investigational drug yielded encouraging initial results, hence the rise. In comparison, the S&P 500 index inched up by 0.8% on the day.HIV drug does well in the labGilead's news was that its second phase 3 trial of HIV drug lenacapav ...