FDA Authorizes First-in-Class Human Challenge Study for Oral Norovirus Antiviral
September 9, 2025 – The Food and Drug Administration has cleared Cocrystal Pharma to proceed with a phase 1b human challenge study evaluating CDI-988, a potential oral antiviral drug for the prevention and treatment of norovirus. This marks a significant step toward developing the first antiviral specifically targeting the highly contagious virus.
Norovirus causes approximately 21 million infections annually in the United States, leading to over 100,000 hospitalizations and nearly 900 deaths each year.The virus spreads easily through contaminated food, surfaces, and close contact, posing a particular risk to immunocompromised individuals, infants, and older adults, who can remain contagious for weeks after recovering.
Preclinical studies have demonstrated CDI-988’s broad antiviral activity, and initial phase 1 testing indicated the drug was well-tolerated. The upcoming challenge study will assess its efficacy in preventing or treating norovirus infection.
“This milestone marks an significant step in advancing CDI-988 into clinical development,” said Sam Lee, PhD, president and co-CEO of Cocrystal Pharma. “The planned challenge study will help determine its efficacy in preventing or treating norovirus infection.”
Cocrystal utilizes a structure-based drug discovery platform, enabling detailed modeling of drug-target interactions to design novel antivirals. Beyond norovirus, CDI-988 has also shown activity against coronaviruses and is currently under investigation as a potential COVID-19 therapy, having received approval from the Australian Human Research Ethics Committee (HREC) to initiate a phase I trial in 2023.
References
Cocrystal Pharma Receives FDA IND Clearance for Challenge Study of Oral Broad-Spectrum Protease Inhibitor CDI-988, a Potential First Antiviral for Norovirus Prevention and Treatment. BioSpace. September 9,2025. Accessed September 9, 2025. https://www.biospace.com/press-releases/cocrystal-pharma-receives-fda-ind-clearance-for-challenge-study-of-oral-broad-spectrum-protease-inhibitor-cdi-988-a-potential-first-antiviral-for-norovirus-prevention-and-treatment?utmsource=chatgpt.com
Cocrystal Pharma’s norovirus antiviral study receives FDA clearance. ClinicalTrialsArena. September 9, 2025. Accessed September 9, 2025. https://www.clinicaltrialsarena.com/news/cocrystal-norovirus-study/?utmsource=chatgpt.com&cf-view
