[Contribution to development of remedies for COVID-19: focusing on Eritoran].

Eritoran (E5564) is Eisai's in-house discovered and developed investigational Toll-Like Receptor 4 (TLR4) antagonist created with natural product organic synthesis technology. It is a structural analogue of Lipid A, which is an activator of endotoxins of bacteria. It has been previously observed to be safe in 14 clinical studies including a large Phase 3 randomized trial in severe sepsis. In order to evaluate therapeutic efficacy by eritoran, we are participating in the international network REMAP-CAP-COVID (Randomized, Embedded, Multi-factorial, Adaptive Platform-Community Acquired Pneumonia COVID) which aims for novel coronavirus medicine development through drug repurposing, and began an international collaborative clinical trial in October 2020 which is designated for confirmed novel coronavirus patients who are hospitalized and are in a progressing disease state. It is hoped that through suppressing the most upstream TLR4 activity which controls production of multiple cytokines by eritoran, the cytokine storm in patients can be suppressed and pneumonia can thus be prevented from becoming severe. On the other hand, E6011 is the only humanized anti-fractalkine (FKN) monoclonal antibody in the world created by KAN Research Institute. E6011 inhibits the tight binding of CD16-positive monocytes (a cell population that highly expresses the FKN receptor CX3CR1) to vascular endothelial cells, which are important for the local inflammatory response. This is expected to suppress the formation and exacerbation of vasculopathy in COVID-19.