Shares of Merck & Co. /zigman2/quotes/209956077/composite MRK +0.88% were up 0.1% in premarket trading on Thursday after the drug company said the oral antiviral COVID-19 treatment it is developing with Ridgeback Biotherapeutics did not help hospitalized patients in a mid-stage clinical trial. The companies now plan to test molnupiravir in non-hospitalized COVID-19 patients in a Phase 3 trial, with plans to file for emergency authorization in the second half of the year. They are also planning to see if the experimental therapy works for post-exposure prophylaxis. In a separate news release, Merck said it is discontinuing MK-7110 as a treatment for patients hospitalized with COVID-19, saying that the Food and Drug Administration's request for additional clinical information would push the launch into 2022. "Merck is now focusing its efforts on advancing molnupiravir, which, as an oral medicine for outpatient use, represents a promising potential new approach, and on accelerating production of Johnson & Johnson's COVID-19 vaccine," Dr. Roy Baynes, chief medical officer for Merck Research Laboratories, said in the release. Merck's stock has gained 6.6% since the start of the year, while the broader S&P 500 /zigman2/quotes/210599714/realtime SPX +1.22% is up 9.8%.