The targeting effect of Hm2E8b–NCTD–liposomes on B-lineage leukaemia stem cells is associated with the HLF–SLUG axis

To identify an agent with specific activity against B-lineage leukaemia stem cells (B-LSCs), we generated norcantharidin (NCTD)-encapsulated liposomes modified with a novel humanised anti-human CD19 monoclonal antibody, Hm2E8b (Hm2E8b–NCTD–liposomes). These liposomes were specially designed to recognise and kill B-LSCs in vitro, and to decrease non-specific cytotoxicity to untargeted cells. Hm2E8b–NCTD–liposomes selectively ablated B-LSCs through targeting hepatic leukaemia factor (HLF), which is implicated in haematopoietic stem cell regulation and is overexpressed in LSCs. Hm2E8b–NCTD–liposomes decreased HLF protein levels and induced apoptosis in the HAL-01 cell line harbouring the oncoprotein E2A–HLF. This resulted in modulation of the expression of several molecules that govern survival pathways, including HLF, SLUG, NFIL3 and C-Myc, thereby causing the induction of p53 and the mitochondrial caspase cascade. Therefore, the potent in vitro effect of Hm2E8b–NCTD–liposomes on B-LSC activity and survival pathways have the potential to be exploited clinically with appropriate drug combinations.