[Pharmacological characteristics and clinical study results of ensitrelvir fumaric acid (XOCOVA Tablets 125 ‍mg)].

Ensitrelvir fumaric acid (Xocova hereafter ensitrelvir) is a novel anti-SARS-CoV-2 drug for COVID-19. Hokkaido University and Shionogi & Co., Ltd. engaged in joint research targeting SARS-CoV-2 3C-like (3CL) protease at an early stage and started clinical trials in July 2021. In February 2022, an application was filed for manufacture and sales approval for the indication of "SARS-CoV-2 infection,". Ensitrelvir recieved the first emergency regulatory approval from the Ministry of Health, Labour and Welfare (MHLW) in Japan in November 2022, and has obtained standard approval in March 2024. This emergency approval was based on the confirmed safety in a Phase 2/3 study (T1221) conducted in Japan and other Asian countries (Korea and Vietnam) in patients with mild/moderate COVID-19 and the presumed efficacy in Phase 3 Part (SCORPIO-SR), and the standard approval is based on efficacy from the Phase 3 part. In the Phase 3 part, ensitrelvir administered orally 375/125 ‍mg once daily for five days, in patients with irrespective of risk factors for severe complications and vaccination status, demonstrating a significant reduction vs placebo in the time to resolution of five typical Omicron-related symptoms (stuffy or runny nose, sore throat, cough, feeling hot or feverish, and low energy or tiredness), and also showed a significant reduction in viral RNA on day 4 relative to placebo (P < 0.001). In the Phase 2/3 study, there were no serious adverse events or deaths, indicating good tolerability and safety. We hope that ensitrelvir will contribute as a new treatment option for patients suffering from COVID-19 symptoms.