Long-awaited anti-COVID drug is also a milestone against future viruses, Pg2

Key Highlights:

• Ensitrelvir, a drug developed by Shionogi, has shown effectiveness in preventing COVID-19 after exposure, according to the SCORPIO-PEP trial.
• The trial involved 2,387 participants and showed that Ensitrelvir reduced the incidence of symptomatic COVID-19 by 67%.
• Ensitrelvir received emergency approval in Japan in November 2022 and full authorization in early 2024 for treating mild-to-moderate COVID-19.
• SARS-CoV-2 has two proteases called the main protease (Mpro), which does most of the cutting, and the Papain-like protease (PLpro).

Detailed Insights:

• Ensitrelvir targets the Mpro protease of SARS-CoV-2, a crucial enzyme for viral replication, and was developed using computational chemistry to screen potential compounds.
• Nirmatrelvir, developed by Pfizer, also targets Mpro but requires Ritonavir to slow down its metabolism, leading to potential drug interactions and side effects.
• The SCORPIO-PEP trial demonstrated that Ensitrelvir not only reduces symptomatic COVID-19 but also lowers the presence of SARS-CoV-2 in exposed individuals.
• Developing drugs that target viral proteins that are essential for the virus while being significantly different from human proteins are extremely valuable drug targets.
• Betacoronaviruses have caused three major outbreaks in just over two decades: SARS-CoV-1, MERS-CoV, and SARS-CoV-2.

Scientific/Technical Concepts Involved:

• Proteases: Enzymes that cut proteins into smaller pieces, essential for viral replication.
• Mpro (Main Protease): A viral enzyme targeted by drugs like Ensitrelvir and Nirmatrelvir to inhibit SARS-CoV-2 replication.
• Computational Chemistry: Using computer simulations to design and screen potential drug candidates.