Nanomedicine of Hedgehog and AKT/ERK Dual Inhibitors for Pancreatic Cancer

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PROJECT SUMMARY Gemcitabine (GEM), a frontline drug, shows limited efficacy due to its rapid metabolism and inefficient delivery to the desmoplastic pancreatic tumor site. Hedgehog (Hh) signaling activates pancreatic stellate cells (PSCs) and plays a critical role in the formation of desmoplasia and proliferation of cancer stem cells (CSCs). KRAS is predominantly mutated in pancreatic cancer (PC), yet KRAS remains a difficult target. Since inhibition of mTORC1/2 increases ERK phosphorylation, we propose combination therapy of GEM with ONC201, which is an AKT/ERK dual inhibitor to effectively treat PC. ONC201 inhibits cell proliferation and induces TNF-related apoptosis inducing ligand (TRAIL)-mediated apoptosis. Further, we have adopted a stroma depletion strategy by sequentially administrating Hh inhibitor MDB5 for reducing physical barrier of drug delivery to the tumor site. While sonic hedgehog (Shh)-deficient tumors have reduced stromal content, such tumors are aggressive with increased vascularity and metastatic potential. Therefore, reduction of desmoplasia by inhibiting Hh pathway will allow efficient delivery of ONC201 and GEM loaded into EGFR targeted NPs to the pancreatic tumor site. We have identified an effective combinatorial treatment strategy using clinically viable inhibitors, which can be applied to PDAC tumors with different KRAS mutations. In our preliminary studies, (i) compared to free GEM, mPEG-co-PCC-g-GEM-g-DC NPs increased GEM accumulation in orthotopic tumor by 2.5-fold. To control GEM release into the tumor, we synthesized mPEG-co-P(Asp)-g-DC-S-S-GEM with GEM payload of 14% w/w. There was 90% GEM release from the polymer upon incubation with L-glutathione (GSH). Combination of GEM with ONC201 showed synergy in killing resistant PC cells in vitro and reduced tumor growth in vivo more effectively than their monotherapies. We also synthesized 2-chloro-N1-[4-chloro-3-(2-pyridinyl) phenyl]-N4, N4-bis(2- pyridinylmethyl)-1,4-benzenedicarboxamide (MDB5), which inhibited Hh ligands and CSC markers more efficiently than vismodegib. Targeted NPs were prepared and optimized by decorating their surface with EGFR binding peptide GE11 at different ligand density. Systemic administration of MDB5 loaded GE11-NPs into PC tumor bearing mice resulted in higher drug concentration in the tumor at 4h post administration compared to non-targeted NPs. Therefore, we hypothesize that sequential administration of MDB5 loaded NPs will increase GEM and ONC201 delivery to the tumor and result in synergistic inhibition of PC by reversing resistance induced by desmoplasia and CSC proliferation more efficiently. Our specific aims are to i) assess the effects of ONC201 and GEM combination in GEM resistant PC cells in vitro and in vivo, ii) development of targeted redox sensitive nanomedicine of MDB5, ONC201 and GEM, and iii) nanoparticulate delivery of MDB5, ONC201, and GEM combination in orthotopic, PDX and spontaneous KPC mouse models. Long-term impact is to develop novel strategies to reduce desmoplasia-induced chemoresistance in PC using multifunctional nanomedicine of MDB5, GEM and ONC201.