Assessment of the Efficacy and Safety of Tecovirimat in Patients With Monkeypox Virus Disease

The study presented here is the Swiss-Brazil co-sponsored adaptation of the UNITY trial based on the WHO core protocol. It has an original governance to better respond to public health priorities, each country being its own sponsor, allowing for an easier scale-up of the trial and local adaptations of the protocol.

Background and rationale:

Monkeypox is an emerging viral zoonosis caused by a virus of the same name that is closely related to smallpox. It is usually endemic in central and West Africa but since May 2022, the virus has rapidly disseminated to Europe, North and South America, Africa and Australia, and has predominantly affected gay, bisexual and other men who have sex with men (MSM) with multiple partners. On 23 July 2022, the World Health Organization (WHO) declared that the monkeypox outbreak was an international public health emergency. In particular, the WHO called for the use of antivirals for the treatment of monkeypox cases. This declaration must therefore be translated not only into extraordinary public health measures but also as a call for greater investment in research.

This study proposal is a national adaptation for Switzerland and Brazil based on the 'CORE protocol' developed by the WHO. The research team would like to emphasize that this randomized trial is international in scope. Thus, they are joining forces to achieve a more effective and rapid response to important questions, with a harmonized follow-up and in a time frame that can be useful to the patients the medical staff have been caring for since the very beginning of this epidemic. Candidate antivirals are already available for testing in monkeypox. The first studied treatment in this adaptative trial is the antiviral tecovirimat. Tecovirimat (TPOXX®, SIGA Technologies Inc.) is a treatment for smallpox, monkeypox and cowpox. Tecovirimat is approved by the European Medicine Agency (EMA) for this indication for adults and children weighing at least 13 kg, as well as by the United States Food and Drugs Administration (FDA) under expanded access investigational new drug protocol, but it is not yet approved in Switzerland and Brazil.

Objectives:

This study aims to evaluate whether tecovirimat is an efficient and safe antiviral in the treatment of monkeypox in adults and adolescents (14 years old and over).

The primary objective is to evaluate the clinical efficacy of tecovirimat treatment + standard of care (SOC) compared to placebo + SOC for patients with monkeypox as assessed by time to visible lesion(s) resolution. The secondary objectives are to evaluate the clinical efficacy and safety of tecovirimat treatment + SOC compared to placebo + SOC in patients with monkeypox as assessed by mortality, hospitalization, complications, duration of symptoms and virological shedding.

Methods:

This study will include adult and adolescent patients aged ≥14 years with a confirmed or highly suspected monkeypox virus infection and with at least one visible active skin or mucosal lesion. Individuals with a known hypersensitivity to tecovirimat, who are taking medications which cannot be interrupted and for which a major interaction has been described or who, in the judgement of the investigator, will be at significantly increased risk as a result of participation in the study will not be included. Randomization will be in a ratio of 1:1 to either tecovirimat treatment combined with SOC or to placebo combined with SOC. All participants will be followed-up until day 29 and additionally at day 60 for those who accept this last optional follow-up visit.

Outcome:

The primary outcome is the time for all visible lesions (skin, mucosal) to heal with a new fresh layer of skin re-epithelialization (i.e. resurfacing of a wound with a new epithelium layer).

Expected results:

The hypothesis is that prompt oral treatment with tecovirimat will result in a reduction of the duration of illness in patients with monkeypox that may correlate with the duration of contagiousness. It is expected that tecovirimat will be well tolerated and acceptable for these patients.