NCT05534984

Study of Tecovirimat for Human Mpox Virus

A Randomized, Placebo-Controlled, Double-Blinded Trial of the Safety and Efficacy of Tecovirimat for the Treatment of Human Mpox Virus Disease

• Status: Terminated
• Phase: Phase 3
• Study type: Interventional
• Enrollment: 719 (actual)
• Sponsor: National Institute of Allergy and Infectious Diseases (NIAID) · NIH
• Sex: All
• Age: —
• Healthy volunteers: Not accepted

Summary

The purpose of this study was to see if tecovirimat is safe and successful at treating mpox. The main questions were whether tecovirimat reduced time to lesion resolution and pain compared to placebo (no treatment).

Detailed description

This phase 3, randomized, placebo-controlled, double-blind clinical trial evaluated the efficacy of tecovirimat for the treatment of mpox. Participants who had or were at higher risk for severe disease because of their age or medical history, were pregnant or breastfeeding, or were taking medications that could have decreased their exposure to tecovirimat were assigned to receive open-label tecovirimat for 14 days. All other participants were randomized 2:1 to receive either tecovirimat or placebo for 14 days. Randomized participants who reported severe pain 5 days after randomization (on Day 6) or later or progressed to severe disease stopped blinded study treatment and started a 14-day course of open-label tecovirimat. Participants self-monitored lesions daily through 28 days (Day 29) or resolution, whichever came first, and completed a daily pain scale and symptom diary. Study visits occurred weekly through 28 days (Day 29) and included safety and skin assessments and specimen collections. A final study visit occurred at 56 days (Day 57) to assess for recrudescence of infection (development of new lesions after initial resolution of disease). Version 3 of the protocol gave participants the option to enroll and complete study visits remotely. Participants did not provide specimens at remote visits. On November 26, 2024, the Data and Safety Monitoring Board (DSMB) recommended that the study close due to statistical futility. The study team and sponsor agreed with the DSMB's recommendation and the study closed to accrual on November 27, 2024. The primary analysis report forming the basis of the primary manuscript used data from follow-up visits occurring through October 23, 2024, the data cutoff for the November 2024 DSMB review (the primary completion date). Outcome measures submitted to clinicaltrials.gov were also based on data from follow-up visits occurring through October 23, 2024, and summaries of participant flow, baseline characteristics, and adverse events submitted to clinicaltrials.gov were based on data from follow-up visits occurring through February 22, 2025 (the study completion date).

Conditions

• MPOX

Interventions

Type	Name	Description
DRUG	Tecovirimat Oral Capsule	* Participants weighing 25 kg to less than 40 kg - Tecovirimat 400 mg every 12 hours for 14 days * Participants weighing 40 kg to less than 120 kg - Tecovirimat 600 mg every 12 hours for 14 days * Participants weighing 120 kg and over - Tecovirimat 600 mg every 8 hours for 14 days
DRUG	Placebo for Tecovirimat	* Participants weighing 25 kg to less than 40 kg - Placebo for Tecovirimat 400 mg every 12 hours for 14 days * Participants weighing 40 kg to less than 120 kg - Placebo for Tecovirimat 600 mg every 12 hours for 14 days * Participants weighing 120 kg and over - Placebo for Tecovirimat 600 mg every 8 hours for 14 days
DRUG	Tecovirimat Oral Capsule (Open Label)	* Participants weighing \<3 kg - Tecovirimat 33.3 mg every 12 hours for 14 days * Participants weighing 3 kg to less than 6 kg- Tecovirimat 50 mg every 12 hours for 14 days * Participants weighing 6 kg to less than 13 kg - Tecovirimat 100 mg every 12 hours for 14 days * Participants weighing 13 kg to less than 25 kg - Tecovirimat 200 mg every 12 hours for 14 days * Participants weighing 25 kg to less than 40 kg - Tecovirimat 400 mg every 12 hours for 14 days * Participants weighing 40 kg to less than 120 kg - Tecovirimat 600 mg every 12 hours for 14 days * Participants weighing 120 kg and over - Tecovirimat 600 mg every 8 hours for 14 days

Timeline

• Start date: 2022-09-08
• Primary completion: 2024-10-23
• Completion: 2025-02-22
• First posted: 2022-09-10
• Last updated: 2026-02-10
• Results posted: 2026-02-10

Locations

54 sites across 6 countries: United States, Argentina, Brazil, Mexico, Peru, Thailand

Regulatory

• FDA-regulated drug study