ABSTRACT
Background and Aims Pancreatic ductal adenocarcinoma (PDAC) is characterized by resistance to therapy. A major contributing factor to therapeutic failure is profound desmoplasia and a well-documented hypoxic tumor microenvironment (TME). In PDAC, several therapeutic approaches, including chemotherapy and radiation alone or combined with immune checkpoint inhibitors, have shown minimal therapeutic success, placing an imperative need for the discovery and application of innovative treatments. Endoscopic ultrasound guided radiofrequency ablation (EUS-RFA) is a promising immunomodulator therapy for PDAC. In this work, we hypothesized RFA promotes local and systemic stromal and immunomodulating effects that can be identified for new combination therapeutic strategies.
Methods To test our hypothesis, a syngeneic PDAC mouse model was performed by symmetrically injecting 100k murine KPC cells in bilateral flanks of C57BL/6 female mice. RFA treatment initiated when tumors reached 200-500 mm3 and was performed only in the right flank. The left flank tumor (non-RFA contralateral side) was used as a paired control for further analysis.
Results RFA promoted a significant reduction in tumor growth rate 4 days after treatment in RFA treated and non-RFA side contralateral tumors from treated mice when compared to controls. Histological analysis revealed a significant increase in expression of cleaved Caspase3 in RFA treated tumors. In addition, collagen deposition and CD31+ cells were significantly elevated in RFA side and non-RFA contralateral tumors from RFA treated mice. Proteome profiling showed changes in C5a and IL-23 in RFA responsive tumors, indicating a role of RFA in modulating intratumoral inflammatory responses.
Conclusions These data indicate RFA promotes local and systemic anti-tumor responses in a syngeneic mouse model of PDAC implicating RFA treatment for local tumors as well as metastatic disease.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
↵# Co-first authors
CONFLICT OF INTEREST: The authors have no conflicts of interest to disclose.
GRANT SUPPORT: The RPPA Core facility at MDAnderson is funded by CA16672. J.B.L received funding from the Texas Medical Center Digestive Disease Center Pilot Award 2P30DK056338-16, a grant from the National Pancreas Foundation and Pathway to Leadership Grant from the Pancreatic Cancer Action Network and American Association for Cancer Research.
ABBREVIATIONS
- RFA
- Radiofrequency ablation
- TME
- Tumor microenvironment
- EUS
- Endoscopic ultrasound
- CAF
- Cancer associated fibroblasts
