Putting remdesivir to the test for COVID-19

As the coronavirus pandemic claims lives and overwhelms health care systems throughout the world, scientists are closely watching several late-stage trials of the antiviral drug remdesivir. Developed to treat Ebola, remdesivir is now being tested against COVID-19. However, many infectious disease experts caution that the trials are unlikely to yield clear-cut results, according to an article in Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society.

Gilead Sciences discovered remdesivir during the 2014 Ebola outbreak in West Africa. Although the drug was not effective in treating late-stage Ebola, it was shown to be fairly safe, Senior Correspondent Lisa Jarvis writes. Remdesivir blocks an enzyme called RNA polymerase that the Ebola virus –– and other RNA viruses, including SARS-CoV-2 –– uses to replicate. Scientists have already shown in lab experiments and animal studies that the drug can help treat and prevent infections of the coronaviruses that cause SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome). Despite hints that remdesivir could also kill SARS-CoV-2, results from current clinical trials will likely be difficult to interpret, experts say. Of the five Phase III studies testing remdesivir against COVID-19, two began in China in early February, one in the U.S. in February and two more in the U.S. in March. Because four of the five studies enrolled patients with moderate-to-severe diseases, which are more difficult to treat than milder cases, a failure of the drug in these trials doesn’t necessarily mean it wouldn’t work for patients treated earlier in the course of infection. Although the U.S. Food and Drug Administration typically takes 6–12 months to approve new drugs, the process will likely be expedited if results from these clinical trials look promising, according to experts. "What can initial remdesivir data tell us about tackling COVID-19?"