Functional and therapeutic effects of Glabrescione B delivery by liposomes on Hedgehog-dependent tumors

Aberrant Hedgehog (HH) signaling pathway is responsible of tumorigenesis of medulloblastoma (MB) and basal cell carcinoma (BCC), two aggressive malignancies with limited therapeutic options. Targeting Gli1, the final and powerful effector of HH signaling, emerged as a valuable strategy for the treatment of HH-dependent tumors. Among Gli1 inhibitors, Glabrescione B (GlaB), is a small molecule that directly inhibits Gli1/DNA interaction, which showed promising pre-clinical results. However, poor solubility limits its clinical translation. To overcome this issue, here we develop a liposomal formulation of GlaB (Lipo/GlaB) with optimized composition to enhance drug loading, controlled release, storage stability and pharmacokinetic performance. Among various formulations, liposomes composed of EPC and cholesterol (95:5 mol/mol%) achieves high GlaB loading efficiency and stability upon lyophilization. Lipo/GlaB inhibits Gli1 transcriptional activity more potently than free GlaB and significantly reduces the expression of HH target genes. Notably, Lipo/GlaB remarkably reduces the tumor growth in HH-driven MB and BCC in in vitro and in vivo models, correlating with decreased HH signaling. Further, pharmacokinetic studies in mice revealed improved plasma disposition, higher AUC, and slower elimination for Lipo/GlaB compared to the free drug. These findings support the therapeutic value of Lipo/GlaB as a selective and potent strategy for targeting HH-dependent cancers, offering improved biopharmaceutical properties and in vivo efficacy compared to non-formulated GlaB.