Norovirus is a worldwide public health problem responsible for close to 90% of epidemic, non-bacterial outbreaks of gastroenteritis around the world. 

Norovirus is a very common and highly contagious virus that causes symptoms of acute gastroenteritis including nausea, vomiting, stomach pain and diarrhea. Other symptoms include fatigue, fever and dehydration. Noroviruses are a major cause of gastrointestinal illness in closed and crowded environments, having become notorious for their common occurrence in hospitals, nursing homes, childcare facilities and cruise ships.

Norovirus is the most common cause of acute gastroenteritis, annually causing an estimated 685 million cases worldwide. About 200 million cases are seen among children under 5 years old, leading to an estimated 50,000 child deaths every year, mostly in developing countries, according to the Centers for Disease Control and Prevention (CDC).

There is currently no effective treatment or effective vaccine for norovirus, and the ability to curtail outbreaks is limited. Few companies, if any, are developing antiviral treatments for this disease. 

By targeting viral replication enzymes and protease, we believe it is possible to develop an effective treatment for all genogroups of norovirus. Also, because of the significant unmet medical need and the possibility of chronic norovirus infection in immunocompromised individuals, new antiviral therapeutic approaches may warrant an accelerated path to market.

We are developing inhibitors of the RNA-dependent RNA polymerase and protease of norovirus. These enzymes are essential to viral replication and are highly conserved between all noroviral genogroups. Therefore, an inhibitor of this enzyme might be an effective therapeutic treatment or short-term prophylactic agent when administered during a cruise or nursing home stay, for example. We have developed x-ray quality norovirus polymerase and protease crystals and have identified promising inhibitors. We are implementing the platform and approaches that have proven successful in our other antiviral programs.

To learn more about norovirus, please visit the information page at the Centers for Disease Control and Prevention (CDC).


Noro Polymerase and Protease Inhibitors

Program Discovery Preclinical Phase 1 Phase 2 Phase 3
Respiratory Viruses Pan-viral Inhibitors
Discovery Phase in progress
Preclinical Phase not started
Phase 1 Phase not started
Phase 2 Phase not started
Phase 3 Phase not started

We selected novel, oral, broad-spectrum protease inhibitor CDI-988 as the lead in our norovirus platform. We are also developing CDI-988 as an oral antiviral for COVID-19. CDI-988 was specifically designed and developed as a broad-spectrum antiviral inhibitor using Cocrystal’s proprietary structure-based drug discovery platform technology. It targets a highly conserved region in the active site of coronaviruses, noroviruses and other 3CL viral proteases. Oral CDI-988 is being evaluated for safety, tolerability and pharmacokinetics in a randomized, double-blind, placebo-controlled Phase 1 study being conducted in Australia.