Enhancing the Immunotherapeutic Effect by IP-001 and Irreversible Electroporation in Mouse Oligometastatic Models of Pancreatic Adenocarcinoma

This study aimed to evaluate the immunotherapeutic effect of irreversible electroporation (IRE) and IP-001 in pancreatic adenocarcinoma with metastasis.

Orthotopic models of pancreatic adenocarcinoma with hepatic oligometastasis were established by implantation of tumor tissues (derived from Pan02 or KPC cells) size 2 mm³ into the pancreas and left liver lobe in C57BL/6J mice. One week after implantation, the tumor-burden mice were subjected to saline control, IRE, IP-001, and IRE+IP-001. For IRE therapy (1000 V, 0.1 ms, 10 pulses administered 10 times), the pancreas tumor was treated, whereas the oligometastasis was untreated as the IRE off-target tumor. Intratumoral administration of IP-001(0.4 ml/kg) was performed.

In the KPC oligometastatic model, IRE+IP-001 therapy significantly suppressed the growth of oligometastatic tumor. Flow cytometry showed significantly increased tumor-infiltrating lymphocytes (TILs) (e.g., CD8⁺ cytotoxic T lymphocytes) and significantly increased monocytes/macrophages in the oligometastatic tumor tissues from IRE+IP-001 treatment compared with the sham control. Significantly decreased Treg cells and tumor-associated macrophages (TAMs) also were found in the oligometastatic tumor tissues from IRE+IP-001 treatment compared with the sham control. In the Pan02 oligometastatic model, both IRE+IP-001 therapy and IRE+anti-PD-L1 immunotherapy significantly suppressed the growth of oligometastatic tumor, which was associated with the increased CD8⁺ cytotoxic T lymphocytes. However, increased monocytes/macrophages were found in the mice that had IRE+IP-001 therapy, but not in the mice that had IRE+anti-PD-L1 immunotherapy.

The study provided compelling evidence for the efficacy of IRE&IP-001 therapy in suppressing pancreatic tumors, including off-target oligometastatic lesions. The observed off-target effect underscores the importance of systemic immune activation in achieving effective tumor control.