Cocrystal doses last subject in CDI-988 norovirus challenge study

Cocrystal Pharma, Inc. (Nasdaq: COCP) said on September 9, 2026 that it has dosed the last subject in its Phase 1b norovirus challenge study evaluating CDI-988 as both a preventive and a treatment for norovirus infections. The company reported no serious adverse events to date. The press release is Exhibit 99.1 to a Form 8-K filed the same day.

The study

The study is registered as NCT07198139. It was conducted at Emory University School of Medicine and is randomized, double-blind and placebo-controlled. It enrolled healthy subjects ages 18-49, who were infected with the norovirus GII.2 (Snow Mountain Virus) strain and given CDI-988 or placebo orally. The primary endpoint is efficacy versus placebo in reducing the incidence of clinical symptoms. Secondary endpoints include reduction of viral shedding and disease severity, along with safety and pharmacokinetic profiles.

The release describes CDI-988 as the first oral antiviral drug candidate developed for norovirus acute gastroenteritis. It is designed to inhibit viral replication in all known norovirus strains. A Phase 1 trial in Australia showed the drug was safe and well tolerated in humans across all dose levels, including the highest dose of 1200 mg. The 1200 mg dose is the one given to the healthy volunteers in the ongoing challenge study.

James Sapirstein, Chief Executive Officer, said: "Completion of this critical milestone brings us closer to addressing one of the most pressing unmet needs in infectious disease." Sam Lee, Ph.D., President and Chief Scientific Officer, said: "The efficacy and safety data from this study are expected to provide a strong rationale for further clinical advancement of CDI-988."

Norovirus and the company

The release puts the disease burden at an estimated 685 million global cases annually. In the U.S., it estimates 21 million infections a year, including 109,000 hospitalizations and an estimated 900 deaths.

The release describes Cocrystal as a company developing antivirals that target the replication process of noroviruses, influenza viruses, coronaviruses (including SARS-CoV-2) and hepatitis C viruses, using structure-based technologies. The company's annual report filed March 31, 2026 describes Cocrystal as a clinical-stage biotechnology company developing antiviral therapeutics for influenza, norovirus, coronaviruses and hepatitis C virus. Its structure-based drug design was developed under Dr. Roger Kornberg, the company's Chief Scientist and Chairman of its Scientific Advisory Board and Board of Directors, who received the Nobel Prize in Chemistry in 2006. The report says the goal is best-in-class, broad-spectrum antiviral drugs with a high barrier to drug resistance.

Financial position and next steps

XBRL data from the 10-K show research and development expense of $5.1 million for 2025, compared with $12.5 million for 2024. The net loss was $8.8 million for 2025 and $17.5 million for 2024. Cash used in operations was $8.2 million for 2025 and $16.5 million for 2024. Cash and cash equivalents were $7.0 million at December 31, 2025, compared with $9.9 million at the end of 2024.

Nothing here shows that CDI-988 works. The release reports no efficacy data, the study is early-stage, and safety so far means no serious adverse events in healthy volunteers. The release's "first" and "strong rationale" language is the company's own. Cash and cash equivalents of $7.0 million at year-end 2025 compare with $8.2 million of cash used in operations that year, and the filings here give no financing plan. The release says the company expects to report preliminary efficacy results near the end of 2026 or in early 2027. The release does not give a date for any later trial phase.

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