Cocrystal’s Lead COVID-19 Antiviral CDI-45205 Shown to be Active Against SARS-CoV-2 & Two Prominent SARS-CoV-2 Variants

Cocrystal Pharma, Inc. recently announced its lead preclinical SARS-CoV-2 3CL protease inhibitor CDI-45205 is active against SARS-CoV-2 and two prominent SARS-CoV-2 variants.

A third-party laboratory contracted by Cocrystal conducted in vitro studies evaluating the antiviral activity of CDI-45205 and its analogs in VeroE6-eGFP cells infected with SARS-CoV-2 (Wuhan strain), the United Kingdom variant (B.1.1.7), and the South African variant (B.1.351). CDI-45205 and its analogs showed excellent antiviral activity against both SARS-CoV-2 variants, surpassing the activity observed with SARS-CoV-2 (Wuhan strain). Two reference inhibitors, including remdesivir, an FDA-approved SARS-CoV-2 RNA-dependent RNA polymerase inhibitor, and PF-00835231, another SARS-CoV-2 3CL protease inhibitor, were included in the study as comparators. Results showed CDI-45205 had excellent antiviral activity against the United Kingdom variant, with an EC50 of 1.9 uM (remdesivir EC50 0.6 uM; PF-00835231 EC50 >100 uM) and against the South African variant, with an EC50 of 2.5 uM (remdesivir EC50 0.8 uM; PF-00835231 EC50 >100 uM) in the absence of a P-glycoprotein efflux inhibitor.

“We are highly encouraged by these results with CDI-45205 against SARS-CoV-2 and two prominent variants of SARS-CoV-2, and we intend to continue with further testing for antiviral activity against other emerging variants including the Indian variant,” said Sam Lee, PhD, Cocrystal’s President and interim co-CEO. “These findings add to the growing body of preclinical data of CDI-45205. We believe these new data suggest our protease inhibitor may be an effective treatment of COVID-19 caused by SARS-CoV-2 and its emerging variants. Additionally, Cocrystal scientists are currently using our proprietary structure-based drug discovery platform technology to investigate broad-spectrum oral protease inhibitors and replication inhibitors for the treatment of COVID-19.”

In December 2020 Cocrystal announced the selection of CDI-45205 as its lead coronavirus development candidate among a group of protease inhibitors obtained under an exclusive license agreement with Kansas State University Research Foundation (KSURF) announced earlier in 2020.

CDI-45205 showed good bioavailability in mouse and rat pharmacokinetic studies via intraperitoneal injection, and also no cytotoxicity against a variety of human cell lines. The Company recently demonstrated a strong synergistic effect with remdesivir. Additionally, a proof-of-concept animal study demonstrated that daily injection of CDI-45205 exhibited favorable in vivo efficacy in MERS-CoV-infected mice. Cocrystal has obtained promising preliminary pharmacokinetic results and is continuing to further evaluate CDI-45205.

Cocrystal Pharma, Inc. is a clinical-stage biotechnology company discovering and developing novel antiviral therapeutics that target the replication process of coronaviruses (including SARS-CoV-2), influenza viruses, hepatitis C viruses and noroviruses. Cocrystal employs unique structure-based technologies and Nobel Prize-winning expertise to create first- and best-in-class antiviral drugs. For more information, visit