The Delivery of a Wnt Pathway Inhibitor Toward CSCs Requires Stable Liposome Encapsulation and Delayed Drug Release in Tumor Tissues

The Wnt signaling pathway is involved in tumorigenesis and various stages of tumor progression, including the epithelial-mesenchymal transition, metastasis, and drug resistance. Many efforts have been made to develop drugs targeting this pathway. CGX1321 is a porcupine inhibitor that can effectively block Wnt ligand synthesis and is currently undergoing clinical trials. However, drugs targeting the Wnt pathway may frequently cause adverse events in normal tissues, such as the intestine and skin. Formulation of the drug inside liposomes could enable preferential drug delivery to solid tumor tissues and limit drug exposure in normal organs. We developed a strategy to stably encapsulate CGX1321 inside liposomes with minimal drug releases in circulation. The liposomal drugs were shown to interfere with the aberrant Wnt signaling specifically in tumor tissues, resulting in focused effects on LGR5(+) CSCs (cancer stem cells), while sparing other cells from significant cytotoxicity. We showed it is feasible to use such a CSC elimination approach to treat malignant cancers prone to rapid progression using a LoVo tumor model as well as a GA007 patient derived xenograft (PDX) model. Nano drug delivery systems may be required for precision medicine in cancer therapy.