COVID-19 is a pandemic infectious respiratory illness caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-COV-2), a positive sense single strand RNA virus. Common symptoms of COVID-19 include fever, cough, and shortness of breath and with a mortality rate of around 4-5%, which is more than 10 times lethal than the flu.

The elderly over 60 or with preexisting conditions, such as hypertension, obesity, asthma, or diabetes, are more susceptible to severe symptoms, and need effective therapy to be cured without other serious complications, such as autoimmune responses.

Entry of SARS-COV-2 virus into host cells considers to be one of the most pivotal events in COVID-19 disease progression. Angiotensin-converting enzyme 2 (ACE2), the main effector of the renin-angiotensin system, is a human cell surface receptor which is predominant in lung, heart and kidney, and found to be an entry for SARS-COV-2. Therefore, SARS-COV-2 easily infects these organs causing multi-organ failure in severe COVID-19 cases.

Inhibition of ACE2 should reduce the SARS-COV-2 infection and associated inflammation. However, either inhibition or knock down of ACE2 may not be a valid therapeutic option for COVID-19 as it is a beneficial molecule. Therefore, CPT-101, a hexapeptide corresponding to Spike S1-interacting domain of ACE2 which is designed to block SARS-COV-2 virus entry into the host cells through inhibiting a small portion of ACE2 receptor. CPT-201 is also a hexapeptide corresponding to the ACE2-interacting domain of SARS-CoV-2 virus capable of specifically targeting SARS-COV-2 Spike S1 and thereby inhibiting the binding between SARS-CoV-2 spike S1 and ACE2 receptor.

CPT-301 ~ CPT-501, small molecules, inhibit the binding of SARS-CoV-2 spike S1 with human ACE2 capable of decreasing viral entry and suppressing inflammation associated with spike S1 intoxication.