Background Pancreatic tumors demonstrate high mortality due to their insidious presentation and subsequent tendency to be locally advanced at the time of diagnosis. Due to involvement of critical structures in this region the percentage of patients who are surgical candidates is low, and the morbidity of surgical resection is high. Additionally, the tumors tend to recur after resection resulting in a dismal 5-year overall survival. Neo-adjuvant and adjuvant systemic therapy does not fare much better, with complete response and long-term survival being the exception rather than the rule. The advent of immunotherapy for cancer has resulted in a paradigm shift, with many systemic immunotherapy pharmaceuticals becoming first-line for various cancers. Pancreatic cancer, however, tends to respond poorly to immunotherapy, possibly due to its propensity to exhibit an ‘immune desert’ tumor microenviornment (TME) phenotype. This refers to a lack of tumor infiltrating lymphocytes and other resident immune cells residing within the tumor, critical to initiate immunologic tumor elimination.

Methods CT-guided pulsed electrical field (PEF) ablation for pancreatic tumors with adjuvant intra-tumoral immunotherapy injection was performed. The ablations were sub-total, and the immunotherapy administered included ipilimumab, nivolumab, and other medications known to elicit an immune response. Medications were administered via the PEF (Galvanize Theraputics, Inc., Redwood City, California, USA) probe outer cannula immediately post-ablation in a gel-matrix for local retention, with contrast for visibility. No immediate complications related to the treatment were observed.

Results We present five patients who underwent PEF ablation plus intratumoral immunotherapy injection for locally advanced and metastatic pancreatic tumors. These patients had exhausted/failed curative treatment options and were receiving palliative treatments for their malignancies. All patients were able to continue with treatment throughout the described treatment regimen. All five patients achieved a response to treatment, with evidence of long-term remission in some cases. Durable radiologic and biochemical responses were seen. All patients continued to have good performance statuses throughout and after the treatment regimen. There were no immediate treatment-related complications. A trans-gastric approach to pancreatic tumors is possible with the low-profile PEF probe, which can also be used to administer the immunotherapy cocktail after ablation. Non-treated tumors were seen to resolve after this treatment, known as the abscopal effect.

Conclusions PEF plus intratumoral immunotherapy is safe and effective for palliation of locally advanced and metastatic pancreatic tumors. Patients may benefit from the abscopal effect when there is diffuse metastatic disease present. Further investigation, including randomized clinical trials may be warranted.