The antiviral drug tecovirimat, developed by Siga Technologies (SIGA), was found not to reduce the time to lesion resolution or have an effect on pain among adults with mild to moderate clade II mpox and a low risk of developing severe disease. This conclusion was drawn from an interim data analysis of the international clinical trial known as the Study of Tecovirimat for Mpox (STOMP).
- No safety concerns were associated with tecovirimat.
- The study's Data Safety and Monitoring Board (DSMB) recommended stopping further enrollment of participants randomized to tecovirimat or placebo.
- The National Institute of Allergy and Infectious Diseases (NIAID), as the study sponsor, accepted the DSMB's recommendation.
- Due to the lack of an efficacy signal, NIAID also closed enrollment into an open-label study arm for participants with or at elevated risk of severe disease, which was not designed to estimate the drug's efficacy.
NIAID Director Jeanne Marrazzo, M.D., M.P.H., emphasized the importance of the findings, stating, "The initial STOMP findings provide valuable insight to inform clade II mpox medical countermeasures and underscore the critical importance of conducting well-designed randomized clinical trials during infectious disease outbreaks." She also highlighted that before 2022, no treatment candidate had been studied in people with mpox, making this trial a crucial step in evaluating existing antivirals like tecovirimat and pursuing novel mpox therapeutics.