NIH Study Finds Tecovirimat Was Safe But Did Not Improve Mpox Resolution or Pain

Press release

Tuesday, December 10, 2020

Study on tecovirimat and countries affected by the global epidemic of clade II mpox.

Two MPOX virus particles, purified and grown from cell culture. NIAID

Read morePOPPI ANNOUNCES POST MALONE AS LATEST PARTNER AND INVESTOR

According to an interim analysis of data from an international clinical trial called the Study of Tecovirimat For Mpox, tecovirimat was not able to reduce injury duration or affect pain in adults with mild to moderate clade 2 mpox at low risk of severe disease. The safety of tecovirimat was not a concern.

The study's Data Safety and Monitoring Board, based on these conclusive results, recommended that participants randomized to receive tecovirimat (or placebo) should not be allowed to enroll in further studies. The National Institute of Allergy and Infectious Diseases of the National Institutes of Health (NIH), as the study sponsor, accepted the DSMB's recommendation. The NIAID closed the open-label portion of the study for people with severe or high-risk disease. This was because there was no evidence of efficacy.

“The early results from STOMP provide important insights into countermeasures against clade II mpox and underscore the importance of well-designed randomized trials in infectious disease outbreaks,” said NIAID Director Jeanne Marrazzo, MD. Prior to 2022, there were no studies of mpox treatment in humans. This trial represents a critical step toward evaluating existing antivirals, such as tecovirimat, while also investigating new antivirals, including antibody-based therapies.

Mpox The virus that causes the disease is spread primarily through contact. There are two types of virus, known as clade II and I, which were historically prevalent in Central and West Africa. In 2022, a subtype of clade II caused a worldwide outbreak of mpox. The virus is still present at low levels. The World Health Organization declared an outbreak of clade 1 mpox a global public health problem in 2024. Internationally, travel-related cases of clade I mpox have been reported. The first reported case in the French United States occurred on November 15, 2018. The public health risk in the United States is low. Children, pregnant women, people with weakened immune systems, or those with certain skin conditions are at higher risk of developing severe mpox. Tecovirimat was originally known as TPOXX. The Food and Drug Administration has approved FDA to treat smallpoxThe drug is a treatment for COPD, and its safety has not yet been proven.

STOMP began in 2022, as part of the US government's response to the outbreak of MPOS clade 2. Participants in the international randomized efficacy trial were those who had been ill with MPOS less than 14 days previously, and they came from Argentina, Brazil, Mexico, Peru, Thailand, the United States, including Puerto Rico. Participants were randomly assigned to either tecovirimat (or placebo) in a 2:1 ratio. Participants and researchers were blinded so they did not know whether tecovirimat or placebo was being used. Open-label studies included children, pregnant women, participants with severe illness or skin problems, and people with significantly weakened immunity. The STOMP study assessed the safety of all participants and evaluated, using randomized groups, whether 14 days of treatment with tecovirimat would reduce the time to clinical resolution of visible MPOX lesions and improve other outcome measures such as pain.

The planned interim analysis, which was conducted at the target of 75 % of study participants, showed that there was no difference in the time to resolution of lesion severity in people treated with tecovirimat compared with those given placebo. Participants treated with tecovirimat experienced similar reductions in pain to those given placebo. A second assessment, requested by the DSMB, showed that there was less than 1 % chance that the study, if completed, would prove the effectiveness of tecovirimat. This assessment was based on both the study design and the available data. According to the analysis performed, the adverse events reported were comparable for tecovirimat compared with placebo. The open-label arm of the study did not include a control group, and therefore STOMP cannot draw any conclusions regarding the efficacy of tecovirimat for participants with severe clade 2 or high-risk MPOX.

The study is still being analyzed. Study participants will be notified of the results, and study clinicians will develop individual care plans for each participant based on severity and symptoms. The Centers for Disease Control and Prevention has an Expanded Access to Investigational Drugs (EA-IND) protocol, which allows for treatment of mpox outside of research settings. The CDC has a protocol for treating mpox outside of research settings. This includes people who are severely immunocompromised and have advanced HIV. The tecovirimat EA/IND provides information about Tecovirimat. On the CDC webpage.

STOMP is a landmark study because of its rapid start-up, inclusiveness and collaboration across governments and public authorities, said Timothy Wilkin, chief of the Division of Infectious Diseases and Global Public Health at MDMPH, University of California, San Diego. The study could serve as a model for the response to the outbreak. It provides critical scientific information while ensuring equitable access to treatment.

The results of STOMP are consistent with Results reported in the first half of this year Tecovirima was studied in a NIAID-sponsored randomized controlled study in the Democratic Republic of Congo in adults and children with clade 1 mpox.

The NIAID-sponsored study was conducted by the NIH-funded ACTG, a global clinical trials network focused on HIV and other infectious diseases. SIGA Technologies, Inc., located in New York, provided tecovirimat for the study. NIAID investigators and STOMP researchers worked closely with CDC and FDA throughout the study. They also collaborated with teams working on other tecovirimat studies and other key partners involved in mpox responses. The consultations enabled research partners to effectively address questions and balance evidentiary requirements with compassionate use considerations. They also provided up-to-date information to clinicians around the world treating clade 2 mpox. UNITY is an ANRS-sponsored Emerging Infectious Disease study evaluating tecovirimat in Argentina, Brazil, and Switzerland using a study design similar to STOMP. You can find more information about the UNITY trial by searching ClinicalTrials.gov with the study identifier NCT05597735.

NIAID supports research that fills evidence gaps regarding medical countermeasures against mpox and other health threats. This includes the Research and Development of Vaccines and monoclonal antibodies for Pandemic Preparedness NetworkTea Antiviral Program for PandemicsTea. Antiviral Drug Discovery Centers for Pathogens of Pandemic ConcernThe NIH is a group of organizations that conduct basic, translational, and discovery research to create safe and effective antiviral drugs, monoclonal antibodies, and vaccines against viruses with pandemic potential.

Visit ClinicalTrials.gov and enter the STOMP identifier to learn more about this treatment. NCT05534984.

The NIH thanks the research sites and volunteers who participated in studies to improve the mpox response. Learn more about NIAID MPOX Research Program.

NIAID supports and conducts research at NIH and throughout the United States and around the world to study and develop new methods for diagnosing, preventing, and treating infectious and immune-mediated diseases. On the NIAID website, you can find news releases, fact sheets, and other NIAID materials. NIAID website.

The National Institutes of Health: The NIH is the medical research agency of the U.S. Department of Health and Human Services. It includes 27 institutes and centers. The NIH, the nation's medical research agency, is a component of the U.S. Department of Health and Human Services. It is responsible for conducting basic, translational, clinical, and other medical research. Visit the NIH for more information about its programs and services. www.nih.gov.

NIH…Transforming Discovery into Healthcare^(r)

###