Virtual Screening–Guided Discovery of Small Molecule CHI3L1 Inhibitors with Functional Activity in Glioblastoma Spheroids

Chitinase-3-like protein 1 (CHI3L1), a glycoprotein implicated in inflammation, fibrosis, and cancer, has emerged as a potential therapeutic target for glioblastoma (GBM). CHI3L1 contributes to tumor progression and immune evasion by promoting STAT3 signaling and mesenchymal transition. To identify small molecule CHI3L1 inhibitors, a structure-based 3D pharmacophore model was developed and applied to virtually screen over 4.4 million compounds from the Enamine collection. Following multi-tiered filtering, 35 candidates were selected for experimental evaluation. Binding validation via microscale thermophoresis (MST) confirmed dose-dependent CHI3L1 interactions for two compounds, 8 and 39 , with dissociation constants (K _d ) of 6.8 µM and 22 µM, respectively. These affinities were further supported by surface plasmon resonance (SPR), which yielded K _d values of 5.69 µM for compound 8 and 17.09 µM for compound 39 . In 3D GBM spheroid models, compound 8 significantly reduced spheroid viability and attenuated phospho-STAT3 levels, consistent with CHI3L1 pathway disruption. These findings identify two promising scaffolds and support the utility of pharmacophore-guided virtual screening for discovering functionally active ligands targeting CHI3L1 in GBM.