STA-21 has been used as a signal transducer and activator of transcription 3 (STAT3) inhibitor to study its effects on glioblastoma and primary glioblastoma cells. It has also been used as a STAT3 dimerization inhibitor to study its effects on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) production in human lung cancer cell line.

STA-21 is a STAT3 inhibitor that reduces the constitutively high STAT3 transcriptional activity in Caov-3 and MDA-MB-435s cultures (by 9.125- and 5.765-fold, respectively, post 48-hr 20 μM treatment) by disrupting STAT3 homodimerization, an essential process for STAT3 nuclear localization and DNA-binding activity. STA-21 selectively inhibits the growth and survival of breast carcinoma cells with constitutive Stat3 signaling (26%, 25%, 56% apoptotic cells, respectively, in MDA-MB-231, MDA-MB-435s, and MDA-MB-468 cultures, respectively, post 48-hr 20 μM treatment) but not those without (<10% apoptosis in MCF7, MDA-MB-453, HSF cultures post 48-hr 20 μM treatmen). STA-21 is reported to alleviate autoimmune inflammation in a murine model of rheumatoid arthritis (RA; 0.5 mg/kg; 3X i.p./week) and reduce airway inflammation in allergic mice with psoriatic inflammation (20 μg/mouse/day topically) in vivo.

STAT3 homodimerization inhibitor with anti-cancer and anti-inflammation efficacy in vitro and in vivo.