Sequential delivery of nanoformulated α-mangostin and triptolide overcomes permeation obstacles and improves therapeutic effects in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease exhibiting the poorest prognosis among solid tumors. The efficacy of conventional therapies has been hindered largely due to the insufficient chemotherapeutic delivery to the dense desmoplastic tumor stroma, and the extremely high or toxic dose needed for chemotherapy. Traditional Chinese Medicine (TCM) contains effective components that can effectively regulate tumor microenvironment and kill tumor cells, providing promising alternatives to PDAC chemotherapy. In this study, two active drug monomers of TCM were screened out and a sequentially targeting delivery regimen was developed to realize the optimized combinational therapy. Transforming growth factor-β (TGF-β) plays an indispensable role in promoting cancer-associated fibroblasts (CAFs) activation and proliferation, and CAFs have caused major physical barriers for chemotherapeutic drug delivery. Herein, CAFs-targeting biodegradable polymer nanoparticle (CRE-NP(α-M)) coated with CREKA peptide and loaded with TCM α-mangostin (α-M) was developed to modulate tumor microenvironment by interfering of TGF-β/Smad signaling pathway. Low pH-triggered micelle modified with CRPPR peptide and loaded with another TCM triptolide was constructed to increase the therapeutic effect of triptolide at the tumor sites and reduced its damage to main organs. As expected, CRE-NP(α-M) effectively inactived CAFs, reduced extracellular matrix production, promoted tumor vascular normalization and enhanced blood perfusion at the tumor site. The sequentially targeting drug delivery regimen, CRP-MC(Trip) following CRE-NP(α-M) pretreatment, exhibited strong tumor growth inhibition effect in the orthotopic tumor model. Hence, sequentially targeting delivery of nanoformulated TCM offers an efficient approach to overcome the permeation obstacles and improve the effect of chemotherapy on PDAC, and provides a novel option to treat desmoplastic tumors.