A synchronized dual drug delivery molecule targeting cancer stem cells in tumor heterogeneity and metastasis

Cancer stem-like cells (CSCs) represent a key barrier to successful therapy for triple-negative breast cancer (TNBC). CSCs promote the emergence of chemoresistance, triggering relapse and resulting in a poor prognosis. We herein present CDF-TM, a new small molecule-based binary prodrug conjugated with SN-38 and 3,4-difluorobenzylidene curcumin (CDF) that is specifically activated in hypoxic conditions. CDF-TM treatment significantly induced apoptosis in TNBC-derived 3D spheroids, accompanied with caspase-3 activation as well as the attenuation of tumor stemness with evidence of reduction in aldehyde dehydrogenase 1 (ALDH1) activity and the CD44^high/CD24^low phenotype. An in vivo orthotopic allograft model was used to investigate its effects on tumor growth and metastasis. The dissemination of CSCs from primary allografts was impaired by CDF-TM, along with inhibition of tumor growth via eradication of CSCs and downregulation of multidrug resistance 1 (MDR1). This new small molecule-based binary prodrug offers a novel therapeutic option for metastatic TNBC.