Efficacy and Viral Dynamics of Tecovirimat in Patients with MPOX: A Multicenter Open-Label, Double-Arm Trial in Japan

Abstract

AbstractIntroductionTecovirimat’s application in treating mpox remains under-researched, leaving gaps in clinical and virological understanding.MethodsThe Tecopox study, conducted in Japan, assessed the efficacy and safety of oral tecovirimat therapy in patients with smallpox or mpox. Patients with mpox enrolled between June 28, 2022, and April 30, 2023, were included. We gathered demographic and clinical details along with blood, urine, pharyngeal swab, and skin lesion samples for viral analysis. A multivariable Tobit regression model was employed to identify factors influencing prolonged viral detection.ResultsNineteen patients were allocated to the tecovirimat group. The median age was 38.5 years, and all were male. Ten patients (52.6%) were infected with the human immunodeficiency virus (HIV). Sixteen patients (84.2%) had severe disease. Nine of the 15 patients (60.0%) (four patients withdrew before day 14) had negative PCR results for skin lesion specimens 14 days after inclusion. The mortality rates on days 14 and 30 were 0% and 0%, respectively. No severe adverse events were reported. HIV status and the number of days from symptom onset to tecovirimat administration were associated with lower Ct values (p= 0.027 and p < 0.001, respectively). The median number of days when PCR testing did not detect the mpox virus in each patient was 19.5 days.ConclusionThe results suggest that early tecovirimat administration might reduce viral shedding duration, thereby mitigating infection spread. Moreover, patients infected with HIV appeared to have prolonged viral shedding, increasing the transmission risk compared to those without HIV.KeypointsThe Tecopox study revealed that early tecovirimat administration might reduce viral shedding duration, thereby mitigating infection spread. Moreover, patients infected with HIV appeared to have prolonged viral shedding, increasing the transmission risk compared to those without HIV.