C-171 is an inhibitor of stimulator of interferon genes (STING).?It binds to STING, inhibits its palmitoylation, and prevents the recruitment and phosphorylation of TBK1.

STING agonist-30 is a potent activator of STING-dependent immune responses, demonstrating broad-spectrum antiviral effects against viruses such as HSV (Herpes Simplex Virus), rotavirus, and SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2).

MSA-2, a potent and orally available non-nucleotide STING agonist, has EC50s of 8.3 and 24 μM for human STING isoforms WT and HAQ, respectively. MSA-2 shows antitumor activity and stimulates interferon-β secretion in tumors, induces tumor regression with durable antitumor immunity, and synergizes with anti-PD-1 in syngeneic mouse tumor models.