Tecovirimat Shows No Improvement for Clade I Mpox

A recent study sponsored by the National Institutes of Health (NIH) and conducted in the Democratic Republic of the Congo (DRC) has found that the antiviral drug tecovirimat does not improve the resolution of clade I mpox lesions. This study was part of a randomized, placebo-controlled trial evaluating tecovirimat's efficacy in treating mpox, a disease endemic to the region. Despite the drug's lack of efficacy in this context, the study reported a lower overall mortality rate of 1.7% among participants compared to the higher mpox mortality rates of 3.6% or more observed generally in the DRC.

Image source: NIH officials webstie

Study Details

The trial, conducted under the NIH’s National Institute of Allergy and Infectious Diseases (NIAID) and in partnership with the DRC’s Institut National de Recherche Biomédicale (INRB), enrolled 597 participants with laboratory-confirmed clade I mpox. Participants were randomly assigned to receive either tecovirimat or a placebo, alongside supportive care, including hydration and treatment for secondary infections. Despite the drug being well-tolerated, it did not accelerate lesion resolution compared to placebo.

Findings and Implications

According to initial results, tecovirimat did not significantly reduce the duration of mpox lesions. The study highlighted the effectiveness of high-quality supportive care in reducing mortality rates. "These findings are disappointing, but they give us essential information and reinforce the need to identify other therapeutic candidates for mpox," said NIAID Director Jeanne Marrazzo, M.D., M.P.H.

Mpox, which has affected Central Africa for decades, is categorized into two clades: Clade I, associated with severe illness and endemic in Central Africa, and Clade II, which generally causes milder symptoms. A subtype of Clade II was responsible for a global mpox outbreak in 2022. The study emphasizes the necessity for further research and development of effective treatments and vaccines for both clades of mpox.

Next Steps

Additional analyses are planned to explore variations in clinical outcomes based on factors such as the severity of disease and genetic variants of mpox. The PALM007 trial, led by co-principal investigators Professor Jean-Jacques Muyembe-Tamfum and Dr. Placide Mbala, will continue to evaluate tecovirimat and other potential treatments. Future studies will also focus on understanding mpox in younger populations and exploring new therapeutic options.

The study was conducted with significant support from various organizations, including the U.S. CDC, the World Health Organization (WHO), and SIGA Technologies, Inc., which provided tecovirimat. For more details on the trial, visit ClinicalTrials.gov with the study identifier NCT05559099.

Highlights

• Tecovirimat did not improve resolution of clade I mpox lesions in the DRC trial.
• The study reported a lower mortality rate (1.7%) compared to the general mpox mortality rate in the region.
• Further research is needed to find effective treatments for mpox, particularly for clade I.
• Future studies will explore mpox treatment for younger populations and other therapeutic candidates.
• The trial underscored the importance of high-quality supportive care in improving outcomes.

Data source: https://www.nih.gov/news-events/news-releases/antiviral-tecovirimat-safe-did-not-improve-clade-i-mpox-resolution-democratic-republic-congo