Use of irreversible electroporation in unresectable pancreatic cancer

Dendritic cell vaccination combined with irreversible electroporation for treating pancreatic cancer-a narrative review

Background and Objective

Pancreatic ductal adenocarcinoma (PDAC) is 3rd most lethal cancer in the USA leading to a median survival of six months and less than 5% 5-year overall survival (OS). As the only potentially curative treatment, surgical resection is not suitable for up to 90% of the patients with PDAC due to late diagnosis. Highly fibrotic PDAC with an immunosuppressive tumor microenvironment restricts cytotoxic T lymphocyte (CTL) infiltration and functions causing limited success with systemic therapies like dendritic cell (DC)-based immunotherapy. In this study, we investigated the potential benefits of irreversible electroporation (IRE) ablation therapy in combination with DC vaccine therapy against PDAC.

Methods

We performed a literature search to identify studies focused on DC vaccine therapy and IRE ablation to boost therapeutic response against PDAC indexed in PubMed, Web of Science, and Scopus until February 20th, 2023.

Key Content and Findings

IRE ablation destructs tumor structure while preserving extracellular matrix and blood vessels facilitating local inflammation. The studies demonstrated IRE ablation reduces tumor fibrosis and promotes CTL tumor infiltration to PDAC tumors in addition to boosting immune response in rodent models. The administration of the DC vaccine following IRE ablation synergistically enhances therapeutic response and extends OS rates compared to the use of DC vaccination or IRE alone. Moreover, the implementation of data-driven approaches further allows dynamic and longitudinal monitoring of therapeutic response and OS following IRE plus DC vaccine immunoablation.

Conclusions

The combination of IRE ablation and DC vaccine immunotherapy is a potent strategy to enhance the therapeutic outcomes in patients with PDAC.

Irreversible electroporation for the management of pancreatic cancer: Current data and future directions

Pancreatic cancer is currently the seventh leading cause of cancer death (4.5% of all cancer deaths) while 80%-90% of the patients suffer from unresectable disease at the time of diagnosis. Prognosis remains poor, with a mean survival up to 15 mo following systemic chemotherapy. Loco-regional thermal ablative techniques are rarely implemented due to the increased risk of thermal injury to the adjacent structures, which can lead to severe adverse events. Irreversible electroporation, a promising novel non-thermal ablative modality, has been recently introduced in clinical practice for the management of inoperable pancreatic cancer as a safer and more effective loco-regional treatment option. Experimental and initial clinical data are optimistic. This review will focus on the basic principles of IRE technology, currently available data, and future directions.

The SAFE Pilot Trial—SAlvage Focal Irreversible Electroporation—For Recurrent Localized Prostate Cancer: Rationale and Study Protocol

Introduction

Currently, the majority of prostate cancer (PCa) recurrences after non-surgical first-line treatment are managed with androgen-deprivation therapy (ADT). Salvage radical prostatectomy (sRP) is a curative alternative to ADT but yields significant morbidity. Preliminary evidence from focal salvage treatments shows similar oncological control but lower morbidity compared to sRP. Among available ablative focal energies, irreversible electroporation (IRE) is a treatment modality that proved promising, especially in treating apical lesions, where PCa most often recurs. Our aim is to test the safety of salvage IRE for recurrent PCa.

Methods

We performed a single-arm pilot feasibility study (IDEAL stage 2a): SAFE, SAlvage Focal irreversible Electroporation for recurrent localized PCa. Twenty patients with biopsy-proven PCa recurrence after primary non-surgical (radiation or ablation) treatment were included. All men will undergo mpMRI ± targeted biopsies, pre-operative PSMA-PET staging before inclusion and sIRE. Outcomes will be evaluated through internationally validated questionnaires and morbidity scales. All men will undergo a control biopsy at one year.

Results

Primary objectives were the evaluation of the safety of sIRE (and patients’ quality of life) after treatment. Secondary objectives were the evaluation of functional outcomes, namely, continence and erectile function changes and evaluation of short-term oncological efficacy.

Conclusions

SAFE is the second pilot study to evaluate sIRE and the first one performed according to the most recent diagnostic and staging imaging standards. sIRE may provide a curative option for recurrent PCa together with lower comorbidities compared to sRP.

Locoregional therapies and their effects on the tumoral microenvironment of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is expected to become the second leading cause of death from cancer by 2030. Despite intensive research in the field of therapeutics, the 5-year overall survival is approximately 8%, with only 20% of patients eligible for surgery at the time of diagnosis. The tumoral microenvironment (TME) of the PDAC is one of the main causes for resistance to antitumoral treatments due to the presence of tumor vasculature, stroma, and a modified immune response. The TME of PDAC is characterized by high stiffness due to fibrosis, with hypo microvascular perfusion, along with an immunosuppressive environment that constitutes a barrier to effective antitumoral treatment. While systemic therapies often produce severe side effects that can alter patients' quality of life, locoregional therapies have gained attention since their action is localized to the pancreas and can thus alleviate some of the barriers to effective antitumoral treatment due to their physical effects. Local hyperthermia using radiofrequency ablation and radiation therapy - most commonly using a local high single dose - are the two main modalities holding promise for clinical efficacy. Recently, irreversible electroporation and focused ultrasound-derived cavitation have gained increasing attention. To date, most of the data are limited to preclinical studies, but ongoing clinical trials may help better define the role of these locoregional therapies in the management of PDAC patients.

Optimizing Patient Selection for Irreversible Electroporation of Locally Advanced Pancreatic Cancer: Analyses of Survival

Background

Irreversible electroporation (IRE) has emerged as a viable consolidative therapy after induction chemotherapy, in which this combination has improved overall survival of locally advanced pancreatic cancer (LAPC). Optimal timing and patient selection for irreversible electroporation remains a clinically unmet need. The aim of this study was to investigate preoperative factors that may assist in predicting progression-free and overall survival following IRE.

Methods

A multi-institutional, prospectively maintained database was reviewed for patients with LAPC treated with induction chemotherapy followed by open-technique irreversible electroporation from 7/2015-5/2019. RECIST 1.1 criteria were used to assess tumor response and radiological progression. Overall survival (OS) and progression-free survival (PFS) were recorded. Survival analyses were performed using Kaplan Meier and Cox multivariable regression analyses.

Results

187 LAPC patients (median age 62 years range, 21 – 91, 65% men, 35% women) were treated with IRE. Median PFS was 21.7 months and median OS from diagnosis was 25.5 months. On multivariable analysis, age ≤ 61 (HR 0.41, 95%CI 0.21-0.78, p<0.008) and no prior radiation (HR 0.49, 95%CI 0.26-0.94, p=0.03) were positive predictors of OS after IRE. Age ≤ 61(HR 0.53, 95%CI, 0.28-.99, p=0.046) and FOLFIRINOX followed by gemcitabine/abraxane induction chemotherapy (HR 0.37,95%CI 0.15-0.89, p=0.027) predicted prolonged PFS after IRE. Abnormal CA19-9 values at the time of surgery negatively impacted both OS (HR 2.46, 95%CI 1.28-4.72, p<0.007) and PFS (HR 2.192, 95%CI 1.143-4.201, p=0.018) following IRE.

Conclusions

Age, CA 19-9 response, avoidance of pre-IRE radiation, and FOLFIRINOX plus gemcitabine/abraxane induction chemotherapy are prominent factors to consider when referring or selecting LAPC patients to undergo IRE.

Perioperative systemic immunophenotype following irreversible electroporation (IRE) predicts recurrence

Comprehensive understanding of the immunophenotypic response to local therapy will likely be required to improve outcomes for pancreatic ductal adenocarcinoma (PDAC). While the desmoplastic stroma has rendered PDAC resistant to immunotherapies, irreversible electroporation (IRE), a non-thermal method of tumor ablation, can overcome some of this resistance and immune suppression. We studied the systemic immunophenotype of patients following local treatment of PDAC. Stored lymphocytes from peripheral blood collected pre- and post-operatively for patients with PDAC who underwent surgical treatment from 12/2018 until 12/2019 were prepared for mass cytometry and a 30-marker panel identifying 37 immune-cell clusters were analyzed and compared to all clinical parameters. Stored lymphocytes from patient samples were collected pre-operatively postoperatively (Day 1, 3, 5 and 14) and during surveillance (Month 3, 6, 9 and 12). Thirty patients with locally advanced pancreatic cancer (LAPC) who underwent IRE were evaluated prospectively for changes in their immunophenotype. No significant differences in baseline demographics or tumor markers were identified. CA19-9 levels were significantly higher among patients who developed a recurrence (P=0.03). In the early perioperative period, CD4 and CD8 central memory cells were significantly higher among patients who did not recur (P=0.02 and 0.009 respectively). These findings were maintained in the late (>3 month) surveillance period. Early natural killer (NK) cells were significantly higher among those who did not recur (P=0.004) in the early postoperative period. The early immune-cell populations of CD4 and CD8 central memory cells and early NK cells were significantly higher among populations who did not recur following IRE for PDAC during the study period, with maintenance of the CD4 and CD8 central memory populations during later surveillance. Monitoring the early immunophenotype may offer opportunities to augment the immune response following tumor-disruptive IRE for PDAC.

Advances in Pancreatic Ductal Adenocarcinoma Treatment

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the deadliest malignancies among all cancers. Despite curative intent, surgery and the use of standard cytotoxic chemotherapy and radiation therapy, PDAC remains treatment-resistant. In recent years, more contemporary treatment modalities such as immunotherapy via checkpoint inhibition have shown some promise in many other malignancies, yet PDAC still eludes an effective curative treatment. In investigating these phenomena, research has suggested that the significant desmoplastic and adaptive tumor microenvironment (TME) of PDAC promote the proliferation of immunosuppressive cells and act as major obstacles to treatment efficacy. In this review, we explore challenges associated with the treatment of PDAC, including its unique immunosuppressive TME. This review examines the role of surgery in PDAC, recent advances in surgical approaches and surgical optimization. We further focus on advances in immunotherapeutic approaches, including checkpoint inhibition, CD40 agonists, and discuss promising immune-based future strategies, such as therapeutic neoantigen cancer vaccines as means of overcoming the resistance mechanisms which underly the dense stroma and immune milieu of PDAC. We also explore unique signaling, TME and stromal targeting via novel small molecule inhibitors, which target KRAS, FAK, CCR2/CCR5, CXCR4, PARP and cancer-associated fibroblasts. This review also explores the most promising strategy for advancement in treatment of pancreatic cancer by reviewing contemporary combinatorial approaches in efforts to overcome the treatment refractory nature of PDAC.

EUS-guided irreversible electroporation using endoscopic needle-electrode in porcine pancreas

BACKGROUND

Endoscopic irreversible electroporation (IRE) can be performed using a flexible, thin, needle-shaped electrode for an endoscopic ultrasound (EUS)-guided procedure. This study aimed to evaluate the feasibility and efficacy of performing EUS-guided IRE with endoscopic needle-electrode in porcine pancreas.

METHODS

Experimental endoscopic IRE on the pancreas were performed by EUS-guided approach in three pigs and compared with surgical approach in three pigs. The animals were killed after 24 h and their pancreases collected.

RESULTS

IRE ablation using endoscopic needle-electrode was successful technically in EUS-guided approaches for the pancreas. Immediately following IRE, the ablated pancreatic tissue showed no gross change except focal hemorrhage. H&E staining presented a well-demarcated ablation site measuring 1.0-1.5 cm in diameter in the pancreas. TUNEL immunohistochemistry showed diffuse cell death along the puncture site 24 h after IRE. No complication was observed in pigs after endoscopic IRE ablation.

CONCLUSION

EUS-guided IRE ablation was feasible and effective for pancreas using the newly developed device.

Physical and Chemical Enhancement of and Adaptive Resistance to Irreversible Electroporation of Pancreatic Cancer

Irreversible electroporation (IRE) can be used to treat cancer by electrical pulses, with advantages over traditional thermal approaches. Here we assess for the first time the IRE response of pancreatic cancer, one of the deadliest forms of cancer, both in vitro and in vivo. We demonstrate that both established and primary cancer cell lines can be destroyed by IRE, but with differential susceptibility and thresholds. We further demonstrate in vitro that viability for a given IRE dose can vary with the local chemistry as outcomes were shown to depend on suspending medium and reduction of glucose in the media significantly improved IRE destruction. Data here also demonstrate that repeated IRE treatments can lead to adaptive resistance in pancreatic carcinoma cells thereby reducing subsequent treatment efficacy. In addition, we demonstrate that physical enhancement of IRE, by re-arranging the pulse sequences without increasing the electrical energy delivered, achieve reduced viability in vitro and decreased tumor growth in an in vivo xenograft model. Together, these results show that IRE can destroy pancreatic cancer in vitro and in vivo, that there are both chemical and physical enhancements that can improve tumor destruction, and that one should guard against adaptive resistance when performing repeated treatments.

[Resection for advanced pancreatic cancer following multimodal therapy]

Pancreatic cancer patients presenting with borderline resectable or locally advanced unresectable tumors remain a therapeutic challenge. Despite the lack of high quality randomized controlled trials, perioperative neoadjuvant treatment strategies are often employed for this group of patients. At present the FOLFIRINOX regimen, which was established in the palliative setting, is the backbone of neoadjuvant therapy, whereas local ablative treatment, such as stereotactic irradiation and irreversible electroporation are currently under investigation. Resection after modern multimodal neoadjuvant therapy follows the same principles and guidelines as upfront surgery specifically regarding the extent of resection, e.g. lymphadenectomy, vascular resection and multivisceral resection. Because it is still exceedingly difficult to predict tumor response after neoadjuvant therapy, a special treatment approach is necessary. In the case of localized stable disease following neoadjuvant therapy, aggressive surgical exploration with serial frozen sections at critical (vascular) margins might be necessary to minimize the risk of debulking procedures and maximize the chance of a curative resection. A multidisciplinary and individualized approach is mandatory in this challenging group of patients.

Electrochemotherapy in pancreatic adenocarcinoma treatment: pre-clinical and clinical studies

Background

Pancreatic adenocarcinoma is currently one of the deadliest cancers with high mortality rate. This disease leads to an aggressive local invasion and early metastases, and is poorly responsive to treatment with chemotherapy or chemo-radiotherapy. Radical resection is still the only curative treatment for pancreatic cancer, but it is generally accepted that a multimodality strategy is necessary for its management. Therefore, new alternative therapies have been considered for local treatment.

Conclusions

Chemotherapeutic resistance in pancreatic cancer is associated to a low penetration of drugs into tumour cells due to the presence of fibrotic stroma surrounding cells. In order to increase the uptake of chemotherapeutic drugs into tumour cells, electrochemotherapy can be used for treatment of pancreatic adenocarcinoma leading to an increased tumour response rate. This review will summarize the published papers reported in literature on the efficacy and safety of electrochemotherapy in pre-clinical and clinical studies on pancreatic cancer.