Water Soluble Polymer Drug Therapies for Targeted Delivery to Pancreatic Cancer

Abstract

Current therapies of advanced staged pancreatic cancer are limited by poor response and high toxicity of chemotherapeutics. As the molecular basis of pancreatic cancer has become better understood the need for a targeted therapy could help provide an increase in therapeutic response while also limiting side effects. N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer drug conjugates have demonstrated their potential use as carriers of small molecule drugs to improve cancer therapies. The overall goal of this research was to develop a polymer peptide drug conjugate based on HPMA copolymers, which can increase the therapeutic index of pancreatic cancer chemotherapy. Previous investigation of the uMUC1 receptor, which is a glycoprotein overexpressed on the surface of pancreatic tumors, has lead to the development of EPPT1, a small peptide has been found to have a strong binding affinity to uMUC1, (Kd=20uM). Our hypothesis HPMA copolymer with an active target EPPT1 to the uMUC1 receptor will enhance therapeutic action of a cancer chemotherapeutic drug such as gemcitabine. In this study, we were successful in the synthesis and characterization of a series of HPMA copolymer-EPPT1-Gemcitabine conjugates. Using model pancreatic cancer cell lines, the binding efficiency, internalization and mechanisms of cellular uptake were evaluated with polymer EPPT1 conjugates. Polymer gemcitabine conjugates were evaluated for efficacy against free gemcitabine. The optimized polymer peptide drug conjugates were evaluated for efficacy and drug release. Results during synthesis and characterization indicated that copolymer yield, solubility and performance were influenced by each incorporation of peptide and drug. Flow cytomentry determined that polymer peptide conjugates were able to bind with Capan-2 and Panc-1 cell lines. Confocal microscopy verified that polymer peptide conjugates were not only getting internalized into the cytoplasm but also routing to the lysosome. Using endocytosis inhibitors, confirmed that polymer peptide conjugates use clathrin mediated endocytosis pathways when getting internalized into the cell. Drug release studies revealed that gemcitabine will detached from the polymer in lysosomal conditions. Polymer drug conjugates compared to free gemcitabine alone against pancreatic cancer cells in MTT assay had equal efficacy. Attachment of the active targeting moiety EPPT1, exhibited that polymer peptide drug conjugates were superior in killing cells to free gemcitabine alone.