High-Throughput Screening and Initial SAR Studies Identify a Novel Submicromolar Potent Human cGAS Inhibitor.

Area of Science:

• Biochemistry
• Immunology
• Neuroscience

Background:

• Cyclic GMP-AMP synthase (cGAS) is a cytosolic DNA sensor that triggers innate immune responses and neuroinflammation via the cGAS-STING pathway.
• Dysregulation of the cGAS-STING pathway is implicated in Alzheimer's disease (AD) and other disorders, making cGAS a potential therapeutic target.

Purpose of the Study:

• To identify novel small molecule inhibitors of human cGAS (h-cGAS) through high-throughput screening.
• To characterize the in vitro activity and develop lead compounds for potential therapeutic development.

Main Methods:

• A high-throughput screening of over 300,000 small molecules was conducted using a modified Kinase Glo Luminescent Kinase assay against h-cGAS.
• Hit compounds were evaluated for in vitro activity, and structure-activity relationship (SAR) analysis was performed on selected candidates.
• Lead compounds were further profiled for their ability to inhibit cGAMP levels in THP1 cells.

Main Results:

• Multiple h-cGAS inhibitors with novel scaffolds and low micromolar in vitro activity were identified.
• RU-0610270, a potent hit (IC50 = 1.88 μM), led to the development of analog cpd 6 with enhanced potency (IC50 = 0.66 μM).
• Cpd 6 demonstrated dose-dependent inhibition of cGAMP levels in THP1 cells with minimal toxicity at effective concentrations.

Conclusions:

• A novel series of potent h-cGAS inhibitors has been discovered, demonstrating promising in vitro efficacy.
• These findings provide a valuable starting point for the development of selective and potent h-cGAS inhibitors for clinical applications in diseases associated with cGAS-STING pathway activation.