Elucidating host cell response pathways and repurposing therapeutics for SARS-CoV-2 and other coronaviruses.

COVID-19, first reported in late 2019, is an ongoing pandemic that has been causing devastation across the globe. Although there are multiple vaccines that can prevent severe symptoms, effective COVID-19 therapeutics are still of importance. Using our proprietary in silico engine, we screened more than 22,000 unique compounds represented by over half a million gene expression profiles to uncover compounds that can be repurposed for SARS-CoV-2 and other coronaviruses in a timely and cost-efficient manner. We then tested 13 compounds in vitro and found three with potency against SARS-CoV-2 with reasonable cytotoxicity. Bortezomib and homoharringtonine are some of the most promising hits with IC50 of 1.39 µM and 0.16 µM, respectively for SARS-CoV-2. Tanespimycin and homoharringtonine were effective against the common cold coronaviruses. In-depth analysis highlighted proteasome, ribosome, and heat shock pathways as key targets in modulating host responses during viral infection. Further studies of these pathways and compounds have provided novel and impactful insights into SARS-CoV-2 biology and host responses that could be further leveraged for COVID-19 therapeutics development.

Discovery of XL888: a novel tropane-derived small molecule inhibitor of HSP90.

With structural guidance, tropane-derived HTS hits were modified to optimize for HSP90 inhibition and a desirable in vivo profile. Through an iterative SAR development process 12i (XL888) was discovered and shown to reduce HSP90 client protein content in PD studies. Furthermore, efficacy experiments performed in a NCI-N87 mouse xenograft model demonstrated tumor regression in some dosing regimens.

Discovery of a novel series of potent and orally bioavailable phosphoinositide 3-kinase γ inhibitors.

The phosphoinositide 3-kinases (PI3Ks) have been linked to an extraordinarily diversified group of cellular functions making these enzymes compelling targets for the treatment of disease. A large body of evidence has linked PI3Kγ to the modulation of autoimmune and inflammatory processes making it an intriguing target for drug discovery. Our high-throughput screening (HTS) campaign revealed two hits that were nominated for further optimization studies. The in vitro activity of the first HTS hit, designated as the sulfonylpiperazine scaffold, was optimized utilizing structure-based design. However, nonoptimal pharmacokinetic properties precluded this series from further studies. An overlay of the X-ray structures of the sulfonylpiperazine scaffold and the second HTS hit within their complexes with PI3Kγ revealed a high degree of overlap. This feature was utilized to design a series of hybrid analogues including advanced leads such as 31 with desirable potency, selectivity, and oral bioavailability.