Shares of Eli Lilly & Co. /zigman2/quotes/200106384/composite LLY +1.87% were down 0.5% in premarket trading on Wednesday, the day after the drug maker confirmed that a clinical trial for its COVID-19 antibody treatment in combination with remdesivir had been paused. Gilead Sciences Inc. /zigman2/quotes/210293917/composite GILD -0.06% received emergency authorization for remdesivir in May as a COVID-19 therapeutic. The National Institutes of Health, which is sponsoring the study assessing the investigational combination treatment, on Tuesday night confirmed that enrollment in the trial had been paused, saying the data safety and monitoring board on Tuesday noticed that the study had "reached a predefined boundary for safety at day five." The trial will continue to collect data and monitor the current 326 participants who have received treatment so far. (Half of those participants received placebo, though all participants get remdesivir.) On Oct. 26, the board will recommend whether enrollment can resume. Lilly's stock is up 14.2% so far this year, while the S&P 500 /zigman2/quotes/210599714/realtime SPX -0.30% has gained 8.7%.