SHELTON, CONNECTICUT -- Tuesday, May 12, 2020 -- NanoViricides, Inc. (NYSE Amer.: NNVC) (the "Company"), a leader in the development of highly effective antiviral therapies based on a novel nanomedicines platform, announced today that it has developed drug candidates that have demonstrated very high anti-viral effectiveness in cell culture studies against multiple coronaviruses.
Two of the tested nanoviricides drug candidates were highly effective in cell culture assays against multiple coronaviruses that infect humans. In particular, they were several-fold more effective than favipravir (aka T-705), against the tested viruses. Favirpravir is a broad-spectrum nucleoside-like analog drug that is in clinical testing against SARS-CoV-2, originally developed by Fujifilm.
The Company has tested its drug candidates for anti-viral effectiveness against two distinctly different, unrelated coronaviruses that cause human disease, namely hCoV-NL63, and hCoV-229E. The assays evaluated the reduction caused by the drug candidate in cell death upon viral infection, formally known as cytopathic effects (CPE) assays.
Human coronavirus NL63 (hCoV-NL63) uses the same ACE2 receptor as the SARS-CoV-2 that causes CoVID-19. Both in terms of its clinical pathology, and its receptor usage, it is known to be very similar to SARS-CoV-2, except much milder. Therefore the Company believes hCoV-NL63 is a good surrogate model for therapeutics development against SARS-CoV-2. H-CoV-NL63 can be studied in a BSL2 lab whereas SARS-CoV-2 currently requires a BSL3 or BSL4 facility.
The Company also found that the same two nanoviricides drug candidates were highly effective against another coronavirus, namely hCoV-229E, that causes seasonal common colds in humans. These nanoviricides drug candidates were several-fold more effective than favipravir in this human common colds coronavirus as well. hCoV-229E uses the APN (Aminopeptidase-N) membrane protein on human cells as its receptor to enter cells, different from hCoV-NL63 and SARS-CoV-2.
The Company believes the fact that these nanoviricides anti-coronavirus drug candidates are highly effective against two distinctly different coronaviruses that use different cellular receptors is very significant. Specifically, it provides confidence to the Company and rational basis to scientists that even if the SARS-CoV-2 coronavirus mutates, the nanoviricides can be expected to continue to remain effective.
Importantly, nanoviricides are designed to act by a novel mechanism of action, trapping the virus particle like the "Venus-fly-trap" flower does for insects. Antibodies, in contrast, only label the virus for other components of the immune system to take care of. It is well known that the immune system is not functioning properly at least in severe COVID-19 patients.
In addition, it is generally thought that SARS-CoV-2 may be able to escape antibodies being developed as drugs. Antibodies are known to become ineffective upon viral mutations. Moreover, there is a significant scientific debate about whether vaccines may be able to produce protective immunity against SARS-CoV-2.
Thus, the Company believes that the nanoviricides drug candidates it has developed are potentially superior to favipravir and are expected to warrant human clinical studies. Oral favipravir and infusion of remdesivir are two anti-viral drugs in clinical trials for the treatment of COVID-19.
Prior to filing for human clinical studies, NanoViricides plans on conducting studies to further determine the effectiveness against SARS-CoV-2, and perform certain animal studies for safety/toxicology.
The Company believes that broad-spectrum anti-coronavirus drugs such as its nanoviricides drug candidates are expected to provide the ideal solution for combatting COVID-19, provided that the candidates show effectiveness in human clinical trials.
The various receptors used by different coronaviruses all appear to fall in the broad family of membrane-associated serine proteases. As a family, they share several structural features. Their substrate specificities are dictated by specific amino acid residues and their positions. However, the coronaviruses do not appear to insert into the specific substrate sites on their receptors as can be broadly deduced from limited, available knowledge of these interactions. NanoViricides believes that this has made it possible for the Company to develop receptor-mimetic virus-binding ligands that have broad-spectrum effectiveness against multiple coronaviruses that use different receptors.
HCoV-NL63 is known to cause severe lower respiratory tract infections in young children leading to hospitalization. The symptoms are generally less severe than SARS-CoV-2 but are similar. In most cases, hCoV-NL63 causes relatively mild disease, often associated with croup, bronchiolitis, and lower respiratory tract disease in children, and is considered to cause some of the common colds in adults.
Thus, the clinical manifestation of hCoV-NL63 infection in pediatric patients is similar to that of SARS-CoV-2, although much less severe. SARS-CoV-2 causes clinically similar milder forms of disease in most patients, but moderate to severe disease requiring hospitalizations in about 15-20% of infected persons. These similarities imply that hCoV-NL63 should be a reasonable model virus for antiviral cell culture and animal studies in BSL2 environment in the course of antiviral drug development for SARS-CoV-2.