EMA Reviews Tecovirimat Efficacy Amid Disappointing Mpox Trial Results

The European Medicines Agency (EMA) has commenced a comprehensive review of Tecovirimat, also known as TPOXX, following preliminary data from clinical trials that suggest the medication may lack effectiveness in treating mpox virus infections. This review, initiated on July 25, 2025, responds to emerging concerns regarding the drug's efficacy, particularly in light of recent clinical trial findings.

Tecovirimat was originally approved in the United States for the treatment of smallpox but was authorized for use in the European Union and the United Kingdom in January 2022 amid an mpox outbreak in Europe. The drug is designed to inhibit the action of a viral protein known as VP37, thereby preventing the reproduction of orthopoxviruses, which include the mpox virus. Despite its intended use, the EMA’s decision to review the drug arises from new evidence that questions its therapeutic benefits.

According to data published in April 2025 in The New England Journal of Medicine, the PALM007 trial, which included 597 participants in the Democratic Republic of the Congo, revealed that Tecovirimat did not significantly reduce the duration of mpox lesions compared to a placebo. The median time to lesion resolution was recorded at 7 days for those receiving Tecovirimat, as opposed to 8 days for the placebo group, indicating minimal clinical advantage (Katz et al., 2025).

Dr. Sheena Meredith, a medical writer and consultant, highlights that the overall mortality rate among trial participants was 1.6%, considerably lower than historical figures typically reported in the DRC. This reduction in mortality was attributed to the high standard of care provided during the trial, rather than the efficacy of Tecovirimat itself.

Further corroboration of the drug's ineffectiveness was found in the STOMP trial, which involved participants from multiple countries with mild-to-moderate mpox. Like PALM007, the STOMP trial also failed to demonstrate any significant benefits of Tecovirimat in terms of lesion resolution compared to placebo (Smith et al., 2025).

The EMA's review is a post-authorization procedure that aims to address safety and efficacy concerns regarding the medication. This review was requested by the European Commission in light of the troubling data emerging from recent trials. In addition to the reviews of PALM007 and STOMP, the agency will consider ongoing studies, including the UNITY trial, which also reported similar findings regarding the drug's efficacy.

Mpox, a zoonotic infection primarily found in West and Central Africa, has seen a rise in cases in Europe, often linked to human-to-human transmission, particularly within interconnected sexual networks. The disease predominantly affects gay and bisexual men, as well as others with multiple sexual partners (WHO, 2025). Symptoms of mpox can appear 1-3 weeks post-infection and include fever, headaches, and a characteristic rash, with a case fatality rate ranging from 0% to 11% during outbreaks.

The EMA's decision to review Tecovirimat underscores the ongoing challenges faced in managing infectious diseases, particularly those that have seen a resurgence in the wake of global health crises. Experts emphasize that while Tecovirimat was initially authorized under 'exceptional circumstances' due to the rarity of the disease, the findings from recent studies necessitate a reevaluation of its clinical application (Dr. Sarah Johnson, Professor of Epidemiology at the University of London, 2025).

As the EMA continues its assessment, the implications for public health policy and treatment protocols regarding mpox remain significant. With no alternative treatments currently authorized for mpox, the need for effective therapeutic options is critical, particularly for vulnerable populations. The outcome of this review may ultimately influence the future direction of mpox treatment strategies in Europe and beyond.