An experimental COVID-19 drug cut the risk of death among severely ill patients by more than half in a late-stage trial – an optimistic development that drove its manufacturer’s stock to fresh highs in trading this week.

The drug, sabizabulin, was so effective in treating COVID-19 cases among hospitalized patients in the phase three trial that independent safety monitors recommended the study be stopped early, according to biopharmaceutical firm Veru Inc.

Veru officials said the experimental treatment lowered the risk of death by 55% among hospitalized patients with moderate to severe cases of COVID-19 compared to those who received a placebo.