SAN DIEGO, Oct. 30, 2025 /PRNewswire/ -- ChemDiv, a global provider of integrated drug discovery solutions, today announced the extension of its Chemistry, Manufacturing and Controls (CMC) services collaboration supporting the clinical development of ratutrelvir, a promising oral antiviral treatment for COVID-19. The announcement follows recent progress by Traws Pharma, Inc. (NASDAQ: TRAW), which dosed the first patient in Phase 2 studies of ratutrelvir in October 2025, with top-line data expected by year-end 2025.

Ratutrelvir, a ritonavir-free Main protease (Mpro/3CL) inhibitor, was discovered and developed ab initio from target to clinic by ChemDiv's medicinal chemistry and virology services teams. Leveraging Molsoft's rational drug design platform and Expert Systems' predictive pharmacology tools, ChemDiv developed ratutrelvir to differentiate from existing COVID-19 treatments by offering high potency against a broad range of native and resistant SARS-CoV-2 strains, a simplified 10-day treatment regimen, and elimination of ritonavir co-administration—potentially avoiding drug-drug interactions that limit patient eligibility for current therapies.

Expert Systems, which collaborated with ChemDiv during ratutrelvir's discovery phase, is now extending its contract with Traws Pharma to support further clinical development through a comprehensive predictive safety pharmacology program. This partnership leverages Expert Systems' advanced AI-enabled drug discovery platform to de-risk clinical progression and accelerate regulatory readiness.

ChemDiv's ongoing collaboration includes:

• CMC process research and scale-up for API (Active Pharmaceutical Ingredient) and DP (Drug Product) manufacturing supporting non-GLP and GLP studies,
• Medicinal chemistry support for backup series development,
• Translational pharmacology services utilizing computational modeling and wet-lab validation,
• Clinical pharmacology consulting to optimize dosing strategies for Phase 2 and beyond.

"We're proud to support the advancement of ratutrelvir from discovery through clinical development," said Ilya Baimetov, COO at ChemDiv. "By combining our integrated medicinal chemistry capabilities with Molsoft's rational design tools and Expert Systems' AI-driven predictive pharmacology, we created a differentiated COVID therapeutic with best-in-class potential. Our continued CMC support ensures Traws has the manufacturing infrastructure and analytical capabilities needed for successful clinical execution and regulatory submission."

Ratutrelvir is currently being evaluated in two Phase 2 studies: a non-inferiority trial comparing ratutrelvir to PAXLOVID® in newly diagnosed COVID-19 patients, and a single-arm trial in PAXLOVID®-ineligible patients—a vulnerable population with limited treatment options. Phase 1 studies demonstrated that ratutrelvir maintained plasma levels approximately 13 times above the EC₅₀ with a 10-day, once-daily dosing regimen without ritonavir, potentially reducing the likelihood of viral rebound and Long COVID risk.

About Ratutrelvir

Ratutrelvir is an investigational oral, small molecule Mpro (3CL protease) inhibitor designed as a broadly acting treatment for SARS-CoV-2/COVID-19 without requiring ritonavir co-administration. Preclinical and Phase 1 studies showed ratutrelvir's differentiated activity against nirmatrelvir-resistant strains and favorable pharmacokinetic profile. Ratutrelvir is currently in Phase 2 clinical development by Traws Pharma.

About Expert Systems, Inc.

Expert Systems is an advanced accelerator platform equipped with a comprehensive, hybrid AI-based system covering the entire spectrum of preclinical drug discovery and early development phases, including target identification, virtual screening, non-clinical and clinical pharmacology, chemical liability assessment, and toxicology. Expert Systems supported ratutrelvir's development as part of its AI-assisted drug discovery accelerator program.

About Traws Pharma, Inc.

Traws Pharma (NASDAQ: TRAW) is a clinical-stage biopharmaceutical company developing novel therapies to target critical threats to human health from respiratory viral diseases. The company is advancing investigational oral small molecule antiviral agents with potent activity against difficult-to-treat or resistant virus strains, including ratutrelvir for COVID-19 and tivoxavir marboxil for influenza.

About ChemDiv

ChemDiv is a fully integrated discovery partner from target to clinic, offering a library of over 12 million screening compounds, 2 trillion feasible chemistries for rational drug design, thousands of pre-designed chemical tool libraries, 70,000 building blocks, and a catalog of 45,000 inhibitors and drugs. Its services include custom medicinal chemistry, CMC, AI-powered CADD, computational pharmacology, lead optimization, translational biology, and clinical pharmacology support.

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