On July 29, 2026, Iscartrelvir Hydrochloride Tablets (brand name: Mprosevir ®), a Class 1 innovative drug jointly developed by Westlake University, Westlake Laboratory, and Westlake Therapeutics, were approved for marketing by the National Medical Products Administration (NMPA). Mprosevir ® is indicated for the treatment of mild to moderate coronavirus disease 2019 (COVID-19) in adults. Mprosevir ® is an independently developed oral small-molecule anti-COVID-19 drug with an entirely novel scaffold. The approval of Mprosevir ® provides patients with a new treatment option with a novel mechanism of action and offers a new Chinese solution for the global response to major public health challenges.
Information from the official NMPA website
Mprosevir ® is an inhibitor of the SARS-CoV-2 main protease 3CLpro. 3CLpro is indispensable for the virus’s self-replication and assembly. Mprosevir ® competitively binds to the substrate-binding pocket of 3CLpro, preventing it from cleaving polyprotein precursors and thereby blocking SARS-CoV-2 replication. Mprosevir ® binds non-covalently to its target, resulting in a low off-target risk and a favorable safety profile. In preclinical and clinical studies, Mprosevir ® has demonstrated significant efficacy and favorable safety. Moreover, Mprosevir ® is a single-agent therapy that does not require co-administration with ritonavir, offering a new treatment option for patients with underlying comorbidities.
Binding mode of the drug molecule with 3CLpro
The approval of Mprosevir ® was primarily based on a multicenter, randomized, double-blind, placebo-controlled Phase III clinical trial evaluating efficacy and safety in patients with mild to moderate COVID-19. A total of 28 hospitals across China participated, enrolling 1,350 participants. The primary efficacy endpoint was time to sustained clinical recovery from the first dose through Day 28.
The study was conducted during the routine management phase of COVID-19 prevention and control and used a positive antigen test as an inclusion criterion, more closely reflecting real-world clinical practice. Most participants had experienced a second or subsequent infection, and the natural recovery time was relatively short. Even under these more challenging conditions, the clinical data confirmed the significant efficacy of Mprosevir ®. Results of the Phase III safety analysis showed that the incidence of adverse events was generally comparable between the Mprosevir ® and placebo groups, with favorable safety and tolerability.
The entirely novel molecular structure of Mprosevir ® originated from de novo screening using a DNA-encoded library (DEL). Mprosevir ® is the world’s first successful case of an innovative small-molecule drug derived from DEL technology. Its approval demonstrates the efficiency and feasibility of an AI- and DEL-based high-throughput screening strategy for drug discovery. Mprosevir ® demonstrates differentiated advantages in molecular design, clinical efficacy, and safety, and will provide a novel treatment option for COVID-19 patients, especially high-risk populations.
Iscartrelvir Hydrochloride Tablets (brand name: Mprosevir)
Dr. Yu Hongtao, co-founder of Westlake Therapeutics, said, “As a company spun off from Westlake University to commercialize its scientific and technological achievements, Westlake Therapeutics has always been committed to discovering and developing innovative drugs for major human diseases. Mprosevir ® is an original innovation achieved by integrating cutting-edge technologies across multiple fields. Its approval for marketing will provide patients with a novel treatment option and serve as an important strategic reserve for addressing major public health challenges. We sincerely thank governments at all levels and regulatory authorities for their careful guidance, our partners for their strong support, and our team members for their dedication and perseverance. In the future, we will continue to focus on innovative drug discovery and development to bring the benefits of innovation to patients more quickly.”