Shionogi Reveals Phase 3 Data: Rapid COVID-19 Symptom Relief

The Phase 3 clinical trial of ensitrelvir, an antiviral medication for COVID-19, has shown promising results in reducing symptom duration in patients with mild to moderate cases of the virus. Conducted across Japan, South Korea, and Vietnam, the trial involved a total of 1,821 participants who were administered either a 125 mg or 250 mg dose of ensitrelvir or a placebo daily for five days. The study specifically focused on patients who had been vaccinated and were infected with the Omicron variant.

The research demonstrated that ensitrelvir, at a dosage of 125 mg, significantly hastened the resolution of five common COVID-19 symptoms associated with the Omicron variant, including a runny or stuffy nose, sore throat, cough, feverishness, and fatigue. The median time to alleviate these symptoms was approximately 7 days for the ensitrelvir group compared to 8 days for the placebo group, marking a difference of around 24 hours. Notably, the study included patients irrespective of their risk factors for severe disease, with over 90% of participants having received two or more doses of the SARS-CoV-2 vaccine.

Ensitrelvir, under the brand name Xocova® in Japan, received emergency regulatory approval in Japan in 2022 and was approved in Singapore in November 2023. However, it is still considered an investigational drug in other regions. The drug has also been granted Fast Track designation by the U.S. Food and Drug Administration, indicating its potential to address an unmet medical need.

The study also achieved its two key secondary endpoints, showing a significant reduction in viral RNA levels on Day 4 and a shorter time to the first negative infectious viral titer in the ensitrelvir group compared to the placebo group. These findings suggest that ensitrelvir could potentially reduce the transmission of SARS-CoV-2.

Safety was a priority in the trial, and while most adverse events were mild, temporary decreases in high-density lipoprotein and increased blood triglycerides were observed as the most common treatment-related adverse events. There were no treatment-related deaths reported.

Shionogi, the company behind ensitrelvir, is dedicated to addressing the global threat of infectious diseases and aims to contribute to societal safety and security through the development of new products and services. The company is also committed to equitable access, including efforts to provide access to low- and middle-income countries.

The COVID-19 pandemic continues to pose challenges worldwide, with new variants emerging and the potential for future surges. While vaccines and some treatments are available, the need for additional options remains critical. Ensitrelvir's success in demonstrating both symptomatic improvement and antiviral effects in a vaccinated population is a significant step forward in the ongoing fight against the pandemic.