Pancreatic ductal adenocarcinoma (PDAC) is an abysmal disease refractory to most standard therapies. Irreversible electroporation (IRE) is a local ablative technique for the clinical treatment of solid tumors, including locally advanced and unresectable PDAC, by intratumorally delivering high-intensity electric pulses to permanently disrupt cell membranes and induce cell death. But the distribution of electric field is uneven within the tumor, and in some regions, tumor cells only experience temporary perturbation to their cell membrane, a phenomenon denoted as reversible electroporation (RE). These tumor cells may survive and therefore are the main culprit of tumor relapse after IRE. We herein showed that RE, although not killing tumor cells, induced DNA double-strand breaks and activated DNA damage repair (DDR) responses. Using reactive oxygen species-sensitive polymeric micelles coloaded with Olaparib, an inhibitor of poly(ADP-ribose) polymerase (PARP), and AZD0156, an inhibitor of ataxia telangiectasia mutated (ATM), the resultant nanoformulation (M-TK-OA) disrupted both homologous recombination and nonhomologous end joining signaling of the DDR response and impaired colony formation in pancreatic cancer cells after RE. The combination of IRE and M-TK-OA significantly prolonged animal survival in both subcutaneous and orthotopic murine PDAC models and elicited CD8+ T cell-mediated antitumor immunity with a sustained antitumor memory. The efficacy of combined IRE and M-TK-OA treatments was partially attributed to the activation of cyclic GMP-AMP synthase-stimulator of interferon genes innate immune responses. Our study suggests that dual inhibition of PARP and ATM with nanomedicine is a promising strategy to enhance the pancreatic cancer response to IRE.
Keywords: 18F-FDG PET/CT; AZD0156; cGAS-STING; olaparib; polymeric micelles.