SPEC-93

SPEC-93 is an uncharged, low-molecular-weight small-molecule inhibitor of signal transducer and activator of transcription 3 (STAT3). Identified through structure-based virtual ligand screening (SB-VLS) of the SPEC database incorporating SH2 domain flexibility, SPEC-93 targets the SH2 domain of STAT3, specifically interacting with the pY+0 binding pocket residues R609 and S613. It inhibits G-CSF-stimulated and constitutive STAT3 phosphorylation (pY-STAT3) and blocks STAT3 binding to the EGFR pY-peptide. SPEC-93 has demonstrated potent growth-inhibitory activity against STAT3-dependent breast cancer cell lines, such as MDA-MB-468 and MDA-MB-231, under both anchorage-dependent and anchorage-independent conditions.