Intravital Imaging to Monitor Therapeutic Response in Moving Hypoxic Regions Resistant to PI3K Pathway Targeting in Pancreatic Cancer

摘要

Application of advanced intravital imaging facilitatesdynamic monitoring of pathway activity upon therapeuticinhibition. Here, we assess resistance totherapeutic inhibition of the PI3K pathway withinthe hypoxic microenvironment of pancreatic ductaladenocarcinoma (PDAC) and identify a phenomenonwhereby pronounced hypoxia-induced resistance isobserved for three clinically relevant inhibitors. Toaddress this clinical problem, we have mapped tumorhypoxia by both immunofluorescence and phosphorescencelifetime imaging of oxygen-sensitivenanoparticles and demonstrate that these hypoxicregions move transiently around the tumor. To overlaythis microenvironmental information with drugresponse, we applied a FRET biosensor for Akt activity,which is a key effector of the PI3K pathway.Performing dual intravital imaging of drug responsein different tumor compartments, we demonstratean improved drug response to a combination therapyusing the dual mTORC1/2 inhibitor AZD2014 with thehypoxia-activated pro-drug TH-302.