High-frequency irreversible electroporation is an effective tumor ablation strategy that induces immunologic cell death and promotes systemic anti-tumor immunity

Emerging role of necroptosis, pyroptosis, and ferroptosis in breast cancer: New dawn for overcoming therapy resistance

Breast cancer (BC) is one of the primary causes of death in women worldwide. The challenges associated with adverse outcomes have increased significantly, and the identification of novel therapeutic targets has become increasingly urgent. Regulated cell death (RCD) refers to a type of cell death that can be regulated by several different biomacromolecules, which is distinctive from accidental cell death (ACD). In recent years, apoptosis, a representative RCD pathway, has gained significance as a target for BC medications. However, tumor cells exhibit avoidance of apoptosis and result in treatment resistance, which emphasizes further studies devoted to alternative cell death processes, namely necroptosis, pyroptosis, and ferroptosis. Here, in this review, we focus on summarizing the crucial signaling pathways of these RCD in BC. We further discuss the molecular mechanism and potentiality in clinical application of several prospective drugs, nanoparticles, and other small compounds targeting different RCD subroutines of BC. We also discuss the benefits of modulating RCD processes on drug resistance and the advantages of combining RCD modulators with conventional treatments in BC. This review will deepen our understanding of the relationship between RCD and BC, and shed new light on future directions to attack cancer vulnerabilities with RCD modulators for therapeutic purposes.

Regulating the Distribution and Accumulation of Charged Molecules by Progressive Electroporation for Improved Intracellular Delivery

The cell membrane separates the intracellular compartment from the extracellular environment, constraining exogenous molecules to enter the cell. Conventional electroporation typically employs high-voltage and short-duration pulses to facilitate the transmembrane transport of molecules impermeable to the membrane under natural conditions by creating temporary hydrophilic pores on the membrane. Electroporation not only enables the entry of exogenous molecules but also directs the intracellular distribution of the electric field. Recent advancements have markedly enhanced the efficiency of intracellular molecule delivery, achieved through the utilization of microstructures, microelectrodes, and surface modifications. However, little attention is paid to regulating the motion of molecules during and after passing through the membrane to improve delivery efficiency, resulting in an unsatisfactory delivery efficiency and high dose demand. Here, we proposed the strategy of regulating the motion of charged molecules during the delivery process by progressive electroporation (PEP), utilizing modulated electric fields. Efficient delivery of charged molecules with an expanded distribution and increased accumulation by PEP was demonstrated through numerical simulations and experimental results. The dose demand can be reduced by 10-40% depending on the size and charge of the molecules. We confirmed the safety of PEP for intracellular delivery in both short and long terms through cytotoxicity assays and transcriptome analysis. Overall, this work not only reveals the mechanism and effectiveness of PEP-enhanced intracellular delivery of charged molecules but also suggests the potential integration of field manipulation of molecular motion with surface modification techniques for biomedical applications such as cell engineering and sensitive cellular monitoring.

Endoscopic duodenal mucosa ablation techniques for diabetes and nonalcoholic fatty liver disease: A systematic review

BACKGROUND

Type 2 diabetes mellitus (T2DM) is increasing at an alarming rate, and only 50% of patients with T2DM achieve or maintain adequate glycemic control with pharmacological therapies. Metabolic surgery demonstrated superior efficacy compared to medical therapy but is unfeasible for most patients with T2DM. Duodenal mucosal resurfacing (DMR) by hydrothermal mucosal ablation, recellularization via electroporation therapy (ReCET), and photodynamic therapy are novel endoscopic procedures that use thermal, electrical, and photochemical energy, respectively, to ablate and reset dysfunctional duodenal mucosa. We assessed the data on the effects of these techniques on glycemic control and nonalcoholic fatty liver disease (NAFLD).

METHODS

We systematically searched independently and in duplicate English and non-English language publications through January 31st, 2024. Outcomes assessed were an improvement in different metabolic health parameters and the safety of duodenal mucosal ablation (DMA) procedures. Outcomes were presented descriptively.

FINDINGS

We selected 12 reports reporting results from 3 randomized and 6 uncontrolled trials (seven evaluating DMR, two evaluating ReCET, all with a low risk of bias) for a total of 317 patients enrolled. DMA reduced HbA1c, fasting plasma glucose, and liver fat. When combined with newer antidiabetic drugs, it allowed insulin discontinuation in up to 86% patients. No major safety signal emerged.

CONCLUSIONS

All DMA techniques improve glucose homeostasis; DMR and ReCET appear to be safe in patients with T2DM. If confirmed by future randomized trials and by trials with histological endpoints in NAFLD, then DMA appears to be a promising alternative or complement option to medications for T2DM and NAFLD treatment.

FUNDING

This study received no funding.

Calculating transmembrane voltage on the electric pulse-affected cancerous cell membrane: using molecular dynamics and finite element simulations

CONTEXT

Electroporation is a technique that creates electrically generated pores in the cell membrane by modifying transmembrane potential. In this work, the finite element method (FEM) was used to examine the induced transmembrane voltage (ITV) of a spherical-shaped MCF-7 cell, allowing researchers to determine the stationary ITV. A greater ITV than the critical value causes permeabilization of the membrane. Furthermore, the present study shows how a specific surface conductivity can act as a stand-in for the thin layer that constitutes a cell membrane as the barrier between extracellular and intracellular environments. Additionally, the distribution of ITV on the cell membrane and its maximum value were experimentally evaluated for a range of applied electric fields. Consequently, the entire cell surface area was electroporated 66% and 68% for molecular dynamics (MD) simulations and FEM, respectively, when the external electric field of 1500 V/cm was applied to the cell suspension using the previously indicated numerical methods. Furthermore, the lipid bilayers' molecular structure was changed, which led to the development of hydrophilic holes with a radius of 1.33 nm. Applying MD and FEM yielded threshold values for transmembrane voltage of 700 and 739 mV, respectively.

METHOD

Using MD simulations of palmitoyloleoyl-phosphatidylcholine (POPC), pores in cell membranes exposed to external electric fields were numerically investigated. The dependence on the electric field was estimated and developed, and the amount of the electroporated cell surface area matches the applied external electric field. To investigate more, a mathematical model based on an adaptive neuro-fuzzy inference system (ANFIS) is employed to predict the percent cell viability of cancerous cells after applying four pulses during electroporation. For MD simulations, ArgusLab, VMD, and GROMACS software packages were used. Moreover, for FEM analysis, COMSOL software package was used. Also, it is worth mentioning that for mathematical model, MATLAB software is used.

Irreversible electroporation promotes a pro-inflammatory tumor microenvironment and anti-tumor immunity in a mouse pancreatic cancer model

Pancreatic cancer is a significant cause of cancer-related mortality and often presents with limited treatment options. Pancreatic tumors are also notorious for their immunosuppressive microenvironment. Irreversible electroporation (IRE) is a non-thermal tumor ablation modality that employs high-voltage microsecond pulses to transiently permeabilize cell membranes, ultimately inducing cell death. However, the understanding of IRE's impact beyond the initiation of focal cell death in tumor tissue remains limited. In this study, we demonstrate that IRE triggers a unique mix of cell death pathways and orchestrates a shift in the local tumor microenvironment driven, in part, by reducing the myeloid-derived suppressor cell (MDSC) and regulatory T cell populations and increasing cytotoxic T lymphocytes and neutrophils. We further show that IRE drives induce cell cycle arrest at the G0/G1 phase in vitro and promote inflammatory cell death pathways consistent with pyroptosis and programmed necrosis in vivo. IRE-treated mice exhibited a substantial extension in progression-free survival. However, within a span of 14 days, the tumor immune cell populations reverted to their pre-treatment composition, which resulted in an attenuation of the systemic immune response targeting contralateral tumors and ultimately resulting in tumor regrowth. Mechanistically, we show that IRE augments IFN- γ signaling, resulting in the up-regulation of the PD-L1 checkpoint in pancreatic cancer cells. Together, these findings shed light on potential mechanisms of tumor regrowth following IRE treatment and offer insights into co-therapeutic targets to improve treatment strategies.

Therapeutic perspectives of high pulse repetition rate electroporation

Electroporation, a technique that uses electrical pulses to temporarily or permanently destabilize cell membranes, is increasingly used in cancer treatment, gene therapy, and cardiac tissue ablation. Although the technique is efficient, patients report discomfort and pain. Current strategies that aim to minimize pain and muscle contraction rely on the use of pharmacological agents. Nevertheless, technical improvements might be a valuable tool to minimize adverse events, which occur during the application of standard electroporation protocols. One recent technological strategy involves the use of high pulse repetition rate. The emerging technique, also referred as "high frequency" electroporation, employs short (micro to nanosecond) mono or bipolar pulses at repetition rate ranging from a few kHz to a few MHz. This review provides an overview of the historical background of electric field use and its development in therapies over time. With the aim to understand the rationale for novel electroporation protocols development, we briefly describe the physiological background of neuromuscular stimulation and pain caused by exposure to pulsed electric fields. Then, we summarize the current knowledge on electroporation protocols based on high pulse repetition rates. The advantages and limitations of these protocols are described from the perspective of their therapeutic application.

Neoadjuvant chemo-immunotherapy is improved with a novel pulsed electric field technology in an immune-cold murine model

Chemo-immunotherapy uses combined systemic therapies for resectable and unresectable tumors. This approach is gaining clinical momentum, but survival increases leave considerable room for improvement. A novel form of Pulsed Electric Field (PEF) ablation combines focal tissue destruction with immune activation in preclinical settings. The PEFs induce lethal cell damage without requiring thermal processes, leaving cellular proteins intact. This affords PEF a favorable safety profile, improved antigenicity, and significant immunostimulatory damage-associated molecular pattern release compared to other focal therapies. Preclinical investigations demonstrate a combinatorial benefit of PEF with immunostimulation. This study evaluates whether this proprietary PEF therapy induces an immunostimulatory effect sufficient to augment systemic neoadjuvant chemotherapy and immunotherapy to reverse metastatic disease in an immune-cold murine tumor model. To determine whether PEF improves a neoadjuvant chemo-immunotherapy standard-of-care, partial PEF ablation was delivered to orthotopically inoculated 4T1 metastatic tumors in addition to combinations of cisplatin chemotherapy and/or αPD-1 immunotherapy, followed by resection. In addition, to determine whether PEF combined with chemo-immunotherapy improves local and metastatic response in unresectable populations, partial PEF ablation was added to chemo-immunotherapy in mice that did not receive resection. Blood cytokines and flow cytometry evaluated immune response. Partial PEF ablation generates an immunostimulatory tumor microenvironment, increases systemic immune cell populations, slows tumor growth, and prolongs survival relative to neoadjuvant systemic therapies-alone. These data suggest the addition of this proprietary PEF locoregional therapy may synergize with systemic standard-of-care paradigms to improve outcomes with potential or demonstrated metastatic disease in both resectable and unresectable patient cohorts.

Pulsed Electric Field Ablation versus Radiofrequency Thermal Ablation in Murine Breast Cancer Models: Anticancer Immune Stimulation, Tumor Response, and Abscopal Effects

PURPOSE

To compare the immune response and survival after size-matched radiofrequency (RF) ablation and a proprietary form of pulsed electric field (PEF) ablation in murine tumors.

MATERIAL AND METHODS

Orthotopically inoculated EMT6 or 4T1 murine tumors received sham, RF ablation, or PEF ablation. 4T1 tumor ablations included subgroups with intraperitoneal checkpoint inhibition immunotherapy (αPD-1). Blood was collected for cytokine profiling and flow cytometry. Tumor size was measured and survival was monitored. Tumor samples were processed for histology, immunohistochemistry, flow cytometry, and cytokine profiling. Lungs were collected from 4T1-bearing mice for hematoxylin and eosin histology to assess metastatic spread and abscopal effect induced by ablation.

RESULTS

PEF elicited distinct immunomodulatory effects, with clear differences in serum and tumor cytokine profiles compared with RF ablation, including intratumoral downregulation of vascular endothelial growth factor, hypoxia-inducible factor 1α, c-MET, interleukin-10, Ki67, and tumor necrosis factor-α (all P < .05). PEF increased innate immune activation, with enhanced recruitment of dendritic cells, M1 macrophages, and natural killer cells coupled with a reduction in M2 macrophages and myeloid-derived suppressor cells (all P < .05). Concurrently, PEF strengthened adaptive immunity compared with RF ablation, characterized by increased antigen-specific T cells and decreased regulatory T cells (all P < .05). PEF stalled tumor growth and increased survival at the end of the study (≥4× versus RFA). Finally, PEF promoted an abscopal effect of clearing metastases in the lungs, which was stronger in combination with αPD-1 than with PEF alone.

CONCLUSIONS

The proprietary form of PEF used in this study evoked a preferential immunostimulatory profile versus RF ablation thermal ablation in mice, with implications for enhancing the therapeutic effectiveness of checkpoint inhibition immunotherapy for immunotherapy-unresponsive tumors.

Peripheral T-cell subsets in radiofrequency ablation for tumors from different origins

BACKGROUNDS

Radiofrequency ablation (RFA) is known to destroy tumoral tissue and activate immune cells. This study aimed to investigate the impact of RFA on peripheral T-cell responses and its relationship with tumor origin and hepatitis status.

METHODS

A retrospective analysis was conducted on 62 patients with various types of tumors, including hepatocellular carcinoma, colorectal cancer, lung cancer, breast cancer, and others, who underwent RFA treatment between June 2017 and December 2018. Blood samples were collected before and one day after RFA treatment. The peripheral T-cell subsets were measured by flow cytometry, and their changes were analyzed.

RESULTS

The study found a decrease in the CD4+CD8-and CD4-CD8+ T-cell subsets after RFA, but no significant changes were observed in the populations of CD4+CD8+ and the CD4+CD8-/CD4-CD8+ ratio. Furthermore, no significant differences were observed in peripheral T-cell subsets concerning tumor type or hepatitis status.

CONCLUSIONS

The study suggests that RFA treatment may have a short-term impact on peripheral T-cell responses, characterized by a decrease in certain T-cell subsets. However, these changes do not seem to be related to the tumor type or hepatitis status of the patients.

The next-generation DNA vaccine platforms and delivery systems: advances, challenges and prospects

Vaccines have proven effective in the treatment and prevention of numerous diseases. However, traditional attenuated and inactivated vaccines suffer from certain drawbacks such as complex preparation, limited efficacy, potential risks and others. These limitations restrict their widespread use, especially in the face of an increasingly diverse range of diseases. With the ongoing advancements in genetic engineering vaccines, DNA vaccines have emerged as a highly promising approach in the treatment of both genetic diseases and acquired diseases. While several DNA vaccines have demonstrated substantial success in animal models of diseases, certain challenges need to be addressed before application in human subjects. The primary obstacle lies in the absence of an optimal delivery system, which significantly hampers the immunogenicity of DNA vaccines. We conduct a comprehensive analysis of the current status and limitations of DNA vaccines by focusing on both viral and non-viral DNA delivery systems, as they play crucial roles in the exploration of novel DNA vaccines. We provide an evaluation of their strengths and weaknesses based on our critical assessment. Additionally, the review summarizes the most recent advancements and breakthroughs in pre-clinical and clinical studies, highlighting the need for further clinical trials in this rapidly evolving field.

Recent strategies for evoking immunogenic Pyroptosis in antitumor immunotherapy

Pyroptosis is a specific type of programmed cell death (PCD) characterized by distinct morphological changes, including cell swelling, membrane blebbing, DNA fragmentation, and eventual cell lysis. Pyroptosis is closely associated with human-related diseases, such as inflammation and malignancies. Since the initial observation of pyroptosis in Shigella flexneri-infected macrophages more than 20 years ago, various pyroptosis-inducing agents, including ions, small molecules, and biological nanomaterials, have been developed for tumor treatment. Given that pyroptosis can activate the body's robust immune response against tumor and promote the formation of the body's long-term immune memory in tumor treatment, its status as a type of immunogenic cell death is self-evident. Therefore, pyroptosis should be used as a powerful anti-tumor strategy. However, there still is a lack of a comprehensive summary of the most recent advances in pyroptosis-based cancer therapy. Therefore, it is vital to fill this gap and inspire future drug design to better induce tumor cells to undergo pyroptosis to achieve advanced anti-tumor effects. In this review, we summarize in detail the most recent advances in triggering tumor cell immunogenic pyroptosis for adequate tumor clearance based on various treatment modalities, and highlight material design and therapeutic advantages. Besides, we also provide an outlook on the prospects of this emerging field in the next development.

Characterizing reversible, irreversible, and calcium electroporation to generate a burst-dependent dynamic conductivity curve

The relationships between burst number, reversible, irreversible, and calcium electroporation have not been comprehensively evaluated in tumor tissue-mimics. Our findings indicate that electroporation effects saturate with a rate constant (τ) of 20 bursts for both conventional and high frequency waveforms (R2 > 0.88), with the separation between reversible and irreversible electroporation thresholds converging at 50 bursts. We find the lethal thresholds for calcium electroporation are statistically similar to reversible electroporation (R2 > 0.99). We then develop a burst-dependent dynamic conductivity curve that now incorporates electroporation effects due to both the electric field magnitude and burst number. Simulated ablation and thermal damage volumes vary significantly between finite element models using either the conventional or new burst-dependent dynamic conductivity curve (p < 0.05). Lastly, for clinically relevant protocols, thermal damage is indicated to not begin until 50 bursts, with maximum nonthermal ablation volumes at 100 bursts (1.5-13% thermal damage by volume). We find that >100 bursts generated negligible increases in ablation volumes with 40-70% thermal damage by volume at 300 bursts. Our results illustrate the need for considering burst number in minimizing thermal damage, choosing adjuvant therapies, and in modeling electroporation effects at low burst numbers.

Harnessing the Electrochemical Effects of Electroporation-Based Therapies to Enhance Anti-tumor Immune Responses

This study introduces a new method of targeting acidosis (low pH) within the tumor microenvironment (TME) through the use of cathodic electrochemical reactions (CER). Low pH is oncogenic by supporting immunosuppression. Electrochemical reactions create local pH effects when a current passes through an electrolytic substrate such as biological tissue. Electrolysis has been used with electroporation (destabilization of the lipid bilayer via an applied electric potential) to increase cell death areas. However, the regulated increase of pH through only the cathode electrode has been ignored as a possible method to alleviate TME acidosis, which could provide substantial immunotherapeutic benefits. Here, we show through ex vivo modeling that CERs can intentionally elevate pH to an anti-tumor level and that increased alkalinity promotes activation of naïve macrophages. This study shows the potential of CERs to improve acidity within the TME and that it has the potential to be paired with existing electric field-based cancer therapies or as a stand-alone therapy.

Dynamics of Cell Death Due to Electroporation Using Different Pulse Parameters as Revealed by Different Viability Assays

The mechanisms of cell death due to electroporation are still not well understood. Recent studies suggest that cell death due to electroporation is not an immediate all-or-nothing response but rather a dynamic process that occurs over a prolonged period of time. To investigate whether the dynamics of cell death depends on the pulse parameters or cell lines, we exposed different cell lines to different pulses [monopolar millisecond, microsecond, nanosecond, and high-frequency bipolar (HFIRE)] and then assessed viability at different times using different viability assays. The dynamics of cell death was observed by changes in metabolic activity and membrane integrity. In addition, regardless of pulse or cell line, the dynamics of cell death was observed only at high electroporation intensities, i.e., high pulse amplitudes and/or pulse number. Considering the dynamics of cell death, the clonogenic assay should remain the preferred viability assay for assessing viability after electroporation.

Golgi Apparatus-Targeted Photodynamic Therapy for Enhancing Tumor Immunogenicity by Eliciting NLRP3 Protein-Dependent Pyroptosis

Innate and adaptive immunity is important for initiating and maintaining immune function. The nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome serves as a checkpoint in innate and adaptive immunity, promoting the secretion of pro-inflammatory cytokines and gasdermin D-mediated pyroptosis. As a highly inflammatory form of cell death distinct from apoptosis, pyroptosis can trigger immunogenic cell death and promote systemic immune responses in solid tumors. Previous studies proposed that NLRP3 was activated by translocation to the mitochondria. However, a recent authoritative study has challenged this model and proved that the Golgi apparatus might be a prerequisite for the activation of NLRP3. In this study, we first developed a Golgi apparatus-targeted photodynamic strategy to induce the activation of NLRP3 by precisely locating organelles. We found that Golgi apparatus-targeted photodynamic therapy could significantly upregulate NLRP3 expression to promote the subsequent release of intracellular proinflammatory contents such as IL-1β or IL-18, creating an inflammatory storm to enhance innate immunity. Moreover, this acute NLRP3 upregulation also activated its downstream classical caspase-1-dependent pyroptosis to enhance tumor immunogenicity, triggering adaptive immunity. Pyroptosis eventually led to immunogenic cell death, promoted the maturation of dendritic cells, and effectively activated antitumor immunity and long-lived immune memory. Overall, this Golgi apparatus-targeted strategy provided molecular insights into the occurrence of immunogenic pyroptosis and offered a platform to remodel the tumor microenvironment.

Successful In Situ Targeting of Pancreatic Tumors in a Novel Orthotopic Porcine Model Using Histotripsy

OBJECTIVE

New therapeutic strategies and paradigms are direly needed to treat pancreatic cancer. The absence of a suitable pre-clinical animal model of pancreatic cancer is a major limitation to biomedical device and therapeutic development. Traditionally, pigs have proven to be ideal models, especially in the context of designing human-sized instruments, perfecting surgical techniques and optimizing clinical procedures for use in humans. However, pig studies have typically focused on healthy tissue assessments and are limited to general safety evaluations because of the inability to effectively model human tumors.

METHODS

Here, we establish an orthotopic porcine model of human pancreatic cancer using RAG2/IL2RG double-knockout immunocompromised pigs and treat the tumors ex vivo and in vivo with histotripsy.

RESULTS

Using these animals, we describe the successful engraftment of Panc-1 human pancreatic cancer cell line tumors and characterize their development. To illustrate the utility of these animals for therapeutic development, we determine for the first time, the successful targeting of in situ pancreatic tumors using histotripsy. Treatment with histotripsy resulted in partial ablation in vivo and reduction in collagen content in both in vivo tumor in pig pancreas and ex vivo patient tumor.

CONCLUSION

This study presents a first step toward establishing histotripsy as a non-invasive treatment method for pancreatic cancer and exposes some of the challenges of ultrasound guidance for histotripsy ablation in the pancreas. Simultaneously, we introduce a highly robust model of pancreatic cancer in a large mammal model that could be used to evaluate a variety biomedical devices and therapeutic strategies.

The implication of pyroptosis in cancer immunology: Current advances and prospects

Pyroptosis is a regulated cell death pathway involved in numerous human diseases, especially malignant tumors. Recent studies have identified multiple pyroptosis-associated signaling molecules, like caspases, gasdermin family and inflammasomes. In addition, increasing in vitro and in vivo studies have shown the significant linkage between pyroptosis and immune regulation of cancers. Pyroptosis-associated biomarkers regulate the infiltration of tumor immune cells, such as CD4+ and CD8+ T cells, thus strengthening the sensitivity to therapeutic strategies. In this review, we explained the relationship between pyroptosis and cancer immunology and focused on the significance of pyroptosis in immune regulation. We also proposed the future application of pyroptosis-associated biomarkers in basic research and clinical practices to address malignant behaviors. Exploration of the underlying mechanisms and biological functions of pyroptosis is critical for immune response and cancer immunotherapy.

Research frontiers of electroporation-based applications in cancer treatment: a bibliometric analysis

OBJECTIVES

Electroporation, the breakdown of the biomembrane induced by external electric fields, has increasingly become a research hotspot for its promising related methods in various kinds of cancers.

CONTENT

In this article, we utilized CiteSpace 6.1.R2 to perform a bibliometric analysis on the research foundation and frontier of electroporation-based applications in cancer therapy. A total of 3,966 bibliographic records were retrieved from the Web of Science Core Collection for the bibliometric analysis. Sersa G. and Mir L. M. are the most indispensable researchers in this field, and the University of Ljubljana of Slovenia is a prominent institution. By analyzing references and keywords, we found that, with a lower recurrence rate, fewer severe adverse events, and a higher success rate, irreversible electroporation, gene electrotransfer, and electrochemotherapy are the three main research directions that may influence the future treatment protocol of cancers.

SUMMARY

This article visualized relevant data to synthesize scientific research on electroporation-based cancer therapy, providing helpful suggestions for further investigations on electroporation.

OUTLOOK

Although electroporation-based technologies have been proven as promising tools for cancer treatment, its radical mechanism is still opaque and their commercialization and universalization need further efforts from peers.

New Surgical Approach to Treat Fibroids and Solid Tumors - Thermal and Nonthermal Ablation

There is a trend toward more minimally invasive treatment for symptomatic uterine fibroids. They are image-guided ablation surgery with focused ultrasound, microwave, and radiofrequency ablations that are becoming tested and used in some medical centers or hospitals. Nevertheless, these image-guided ablation surgeries involve thermal ablation to the fibroids, which might lead to thermal injury to the surrounding tissues, for example, nerve injury, vessel injury, and skin burn due to heat diffusion. A new technology - irreversible electroporation (IRE) - is a new paradigm for treating solid tumors. This nonthermal ablation process does not induce high temperatures when treating cancers or solid tumors. The IRE treatment may soon be used for treating fibroids or other solid tumors. In a few clinical trials, IRE is currently used in experimental studies for treating gynecological cancers. This paper will present the minimally invasive thermal ablation treatments for fibroids, introduce this new nonthermal IRE ablation in treating gynecological cancer, and propose its future uses in uterine fibroids.

Determination of the Impact of High-Intensity Pulsed Electromagnetic Fields on the Release of Damage-Associated Molecular Pattern Molecules

High-Intensity Pulsed Electromagnetic Fields (HI-PEMF) treatment is an emerging noninvasive and contactless alternative to conventional electroporation, since the electric field inside the tissue is induced remotely by an externally applied pulsed magnetic field. Recently, HI-PEMF has been successfully used in the transfer of plasmid DNA and siRNA in vivo, with no or minimal infiltration of immune cells. In addition to gene electrotransfer, treatment with HI-PEMF has also shown potential for electrochemotherapy, where activation of the immune response contributes to the treatment outcome. The immune response can be triggered by immunogenic cell death that is characterized by the release of damage-associated molecular patterns (DAMPs) from damaged or/and dying cells. In this study, the release of the best-known DAMP molecules, i.e., adenosine triphosphate (ATP), calreticulin and high mobility group box 1 protein (HMBG1), after HI-PEMF treatment was investigated in vitro on three different cell lines of different tissue origin and compared with conventional electroporation treatment parameters. We have shown that HI-PEMF by itself does not cause the release of HMGB1 or calreticulin, whereas the release of ATP was detected immediately after HI-PEMF treatment. Our results indicate that HI-PEMF treatment causes no to minimal release of DAMP molecules, which results in minimal/limited activation of the immune response.

Molecular mechanisms of pyroptosis and its role in anti-tumor immunity

Pyroptosis is a form of cell death that is characterized by the destruction of the cell, and it has implications in both the immune system and cancer immunotherapy. The gasdermin family is responsible for the activation of pyroptosis, which involves the formation of pores in the cellular membrane that permit the discharge of inflammatory factors. The inflammasome response is a powerful mechanism that helps to eliminate bacteria and cancer cells when cellular damage occurs. As tumor cells become more resilient to apoptosis, other treatments for cancer are becoming more popular. It is essential to gain a thorough understanding of pyroptosis in order to use it in cancer treatment, considering the intricate association between pyroptosis and the immune system's defensive reaction against tumors. This review offers an overview of the mechanisms of pyroptosis, the relationship between the gasdermin family and pyroptosis, and the interplay between pyroptosis and anti-tumor immunity. In addition, the potential implications of pyroptosis in cancer immunotherapy are discussed. Additionally, we explore future research possibilities and introduce a novel approach to tumor treatment.

The effects of irreversible electroporation triggering anti-tumor immunity and the value of its combination with immunotherapy

Recently, interventional ablation techniques have gained prominence in tumor treatment guidelines and complement traditional approaches, such as surgery, chemotherapy, and radiotherapy. Conventional ablation techniques, such as microwave, radiofrequency, and cryoablation, have been used; however, they have certain limitations, including the risk of damaging surrounding normal tissues and the heat sink effect caused by tumor blood flow.1 Irreversible electroporation (IRE), an ablation technology independent of thermal energy, is a promising alternative.2 Clinical studies have demonstrated IRE's efficacy in treating tumors, such as pancreatic and liver tumors.3 Recent research has shown that IRE can elicit specific anti-tumor immune responses in the body.5 IRE also plays a crucial role in eliminating residual tumor cells postoperatively and preventing tumor recurrence.

Denatured collagen inhibits neuroblastoma tumor-sphere migration and growth via the LOX/LOXL2 - FAK signaling pathway

A complex interplay exists within the tumor microenvironment and extracellular matrix, which could contribute to solid tumor progression. Collagen, a major component of the extracellular matrix, may correlate with cancer prognosis. While thermal ablation has shown promise as a minimally invasive treatment of solid tumors, its impact on collagen is still unknown. In this study, we demonstrate that thermal ablation, but not cryo-ablation, induces irreversible collagen denaturation in a neuroblastoma sphere model. Prolonged collagen denaturation resulted in a significant reduction in sphere stiffness, migration, and proliferation, and an increase in apoptosis. Mechanistic analysis revealed that collagen denaturation inhibited collagen cross-linking, reduced extracellular LOX/LOXL2 expression, and resulted in decreased phosphorylation of FAK. Downstream of FAK, we observed reduced epithelial to mesenchymal transition, attenuated CDC42 expression, and decreased migration. Collectively, these results suggest that denatured collagen presents a novel target for modulating the tumor microenvironment and treating solid cancers via the LOX1/LOXL2-FAK signaling pathway.

Pulsed Electric Fields in Oncology: A Snapshot of Current Clinical Practices and Research Directions from the 4th World Congress of Electroporation

The 4th World Congress of Electroporation (Copenhagen, 9-13 October 2022) provided a unique opportunity to convene leading experts in pulsed electric fields (PEF). PEF-based therapies harness electric fields to produce therapeutically useful effects on cancers and represent a valuable option for a variety of patients. As such, irreversible electroporation (IRE), gene electrotransfer (GET), electrochemotherapy (ECT), calcium electroporation (Ca-EP), and tumour-treating fields (TTF) are on the rise. Still, their full therapeutic potential remains underappreciated, and the field faces fragmentation, as shown by parallel maturation and differences in the stages of development and regulatory approval worldwide. This narrative review provides a glimpse of PEF-based techniques, including key mechanisms, clinical indications, and advances in therapy; finally, it offers insights into current research directions. By highlighting a common ground, the authors aim to break silos, strengthen cross-functional collaboration, and pave the way to novel possibilities for intervention. Intriguingly, beyond their peculiar mechanism of action, PEF-based therapies share technical interconnections and multifaceted biological effects (e.g., vascular, immunological) worth exploiting in combinatorial strategies.

Tumor cuproptosis and immune infiltration improve survival of patients with hepatocellular carcinoma with a high expression of ferredoxin 1

Background

Cuproptosis is a novel cell death pathway dependent on cellular copper ions and ferredoxin 1 (FDX1). Hepatocellular carcinoma (HCC) is derived from healthy liver as a central organ for copper metabolism. It remains no conclusive evidence whether cuproptosis is involved in survival improvement of patients with HCC.

Method

A 365-liver hepatocellular carcinoma (LIHC) cohort with RNA sequencing data and paired clinical and survival information was obtained from the The Cancer Genome Atlas (TCGA) dataset. A retrospective cohort of 57 patients with HCC with stages I/II/III was collected by Zhuhai People's Hospital from August 2016 to January 2022. Low- or high-FDX1 groups were divided according to the median value of FDX1 expression. Cibersort, single-sample gene set enrichment analysis, and multiplex immunohistochemistry analyzed immune infiltration in LIHC and HCC cohorts. Cell proliferation and migration of HCC tissues and hepatic cancer cell lines were evaluated using the Cell Counting Kit-8. Quantitative real-time PCR and RNA interference measured and downregulated FDX1 expression. Statistical analysis was conducted by R and GraphPad Prism software.

Results

High FDX1 expression significantly enhanced survival of patients with LIHC from the TCGA dataset, which was also demonstrated through a retrospective cohort with 57 HCC cases. Immune infiltration was different between the low- and high-FDX1 expression groups. Natural killer cells, macrophages, and B cells were significantly enhanced, and PD-1 expression was low in the high-FDX1 tumor tissues. Meanwhile, we found that a high expression of FDX1 decreased cell viability in HCC samples. HepG2 cells with FDX1 expression are sensitive to Cu²⁺, and interference of FDX1 promoted proliferation and migration of tumor cells. The consistent results were also demonstrated in Hep3B cells.

Conclusion

This study reveals that cuproptosis and tumor immune microenvironment were together involved in improvement of survival in patients with HCC with a high expression of FDX1.

Recent Advancements in Electroporation Technologies: From Bench to Clinic

Over the past decade, the increased adoption of electroporation-based technologies has led to an expansion of clinical research initiatives. Electroporation has been utilized in molecular biology for mammalian and bacterial transfection; for food sanitation; and in therapeutic settings to increase drug uptake, for gene therapy, and to eliminate cancerous tissues. We begin this article by discussing the biophysics required for understanding the concepts behind the cell permeation phenomenon that is electroporation. We then review nano- and microscale single-cell electroporation technologies before scaling up to emerging in vivo applications.

Studying the roles of salt ions in the pore initiation and closure stages in the biomembrane electroporation

Electroporation shows great potential in biology and biomedical applications. However, there is still a lack of reliable protocol for cell electroporation to achieve a high perforation efficiency due to the unclear influence mechanism of various factors, especially the salt ions in buffer solution. The tiny membrane structure of a cell and the electroporation scale make it difficult to monitor the electroporation process. In this study, we used both molecular dynamics (MD) simulation and experimental methods to explore the influence of salt ions on the electroporation process. Giant unilamellar vesicles (GUVs) were constructed as the model, and sodium chloride (NaCl) was selected as the representative salt ion in this study. The results show that the electroporation process follows lag-burst kinetics, where the lag period first appears after applying the electric field, followed by a rapid pore expansion. For the first time, we find that the salt ion plays opposite roles in different stages of the electroporation process. The accumulation of salt ions near the membrane surface provides an extra potential to promote the pore initiation, while the charge screening effect of the ions within the pore increases the line tension of the pore to induce the instability of the pore and lead to the closure. The GUV electroporation experiments obtain qualitatively consistent results with MD simulations. This work can provide guidance for the selection of parameters for cell electroporation process.

Immunogenic Cell Death in Electroporation-Based Therapies Depends on Pulse Waveform Characteristics

Traditionally, electroporation-based therapies such as electrochemotherapy (ECT), gene electrotransfer (GET) and irreversible electroporation (IRE) are performed with different but typical pulse durations-100 microseconds and 1-50 milliseconds. However, recent in vitro studies have shown that ECT, GET and IRE can be achieved with virtually any pulse duration (millisecond, microsecond, nanosecond) and pulse type (monopolar, bipolar-HFIRE), although with different efficiency. In electroporation-based therapies, immune response activation can affect treatment outcome, and the possibility of controlling and predicting immune response could improve the treatment. In this study, we investigated if different pulse durations and pulse types cause different or similar activations of the immune system by assessing DAMP release (ATP, HMGB1, calreticulin). Results show that DAMP release can be different when different pulse durations and pulse types are used. Nanosecond pulses seems to be the most immunogenic, as they can induce the release of all three main DAMP molecules-ATP, HMGB1 and calreticulin. The least immunogenic seem to be millisecond pulses, as only ATP release was detected and even that assumingly occurs due to increased permeability of the cell membrane. Overall, it seems that DAMP release and immune response in electroporation-based therapies can be controlled though pulse duration.

Microarray Chip and Method for Simultaneous and Highly Consistent Electroporation of Multiple Cells of Different Sizes

Cell electroporation is an important cell manipulation technology to artificially transfer specific extracellular components into cells. However, the consistency of substance transport during the electroporation process is still an issue due to the wide size distribution of the natural cells. In this study, a cell electroporation microfluidic chip based on a microtrap array is proposed. The microtrap structure was optimized for single-cell capture and electric field focusing. The effects of the cell size on the cell electroporation in the microchip were investigated through simulation and experiment methods using the giant unilamellar vesicle as the simplified cell model, and a numerical model of a uniform electric field was used as a comparison. Compared with the uniform electric field, a lower threshold electric field is required to induce electroporation and produces a higher transmembrane voltage on the cell under a specific electric field in the microchip, showing an improvement in cell viability and electroporation efficiency. The larger perforated area produced on the cells in the microchip under a specific electric field allows a higher substance transfer efficiency, and the electroporation results are less affected by the cell size, which is beneficial for improving substance transfer consistency. Furthermore, the relative perforation area increases with the decrease of the cell diameter in the microchip, which is exactly opposite to that in a uniform electric field. By manipulating the electric field applied to the microtrap individually, a consistent proportion of substance transfer during electroporation of cells with different sizes can be achieved.

High-frequency irreversible electroporation improves survival and immune cell infiltration in rodents with malignant gliomas

Background

Irreversible electroporation (IRE) has been previously investigated in preclinical trials as a treatment for intracranial malignancies. Here, we investigate next generation high-frequency irreversible electroporation (H-FIRE), as both a monotherapy and a combinatorial therapy, for the treatment of malignant gliomas.

Methods

Hydrogel tissue scaffolds and numerical modeling were used to inform in-vivo H-FIRE pulsing parameters for our orthotopic tumor-bearing glioma model. Fischer rats were separated into five treatment cohorts including high-dose H-FIRE (1750V/cm), low-dose H-FIRE (600V/cm), combinatorial high-dose H-FIRE + liposomal doxorubicin, low-dose H-FIRE + liposomal doxorubicin, and standalone liposomal doxorubicin groups. Cohorts were compared against a standalone tumor-bearing sham group which received no therapeutic intervention. To further enhance the translational value of our work, we characterize the local and systemic immune responses to intracranial H-FIRE at the study timepoint.

Results

The median survival for each cohort are as follows: 31 days (high-dose H-FIRE), 38 days (low-dose H-FIRE), 37.5 days (high-dose H-FIRE + liposomal doxorubicin), 27 days (low-dose H-FIRE + liposomal doxorubicin), 20 days (liposomal doxorubicin), and 26 days (sham). A statistically greater overall survival fraction was noted in the high-dose H-FIRE + liposomal doxorubicin (50%, p = 0.044), high-dose H-FIRE (28.6%, p = 0.034), and the low-dose H-FIRE (20%, p = 0.0214) compared to the sham control (0%). Compared to sham controls, brain sections of rats treated with H-FIRE demonstrated significant increases in IHC scores for CD3+ T-cells (p = 0.0014), CD79a+ B-cells (p = 0.01), IBA-1+ dendritic cells/microglia (p = 0.04), CD8+ cytotoxic T-cells (p = 0.0004), and CD86+ M1 macrophages (p = 0.01).

Conclusions

H-FIRE may be used as both a monotherapy and a combinatorial therapy to improve survival in the treatment of malignant gliomas while also promoting the presence of infiltrative immune cells.

Combining energy-based focal ablation and immune checkpoint inhibitors: preclinical research and clinical trials

Energy-based focal therapy (FT) uses targeted, minimally invasive procedures to destroy tumors while preserving normal tissue and function. There is strong emerging interest in understanding how systemic immunity against the tumor can occur with cancer immunotherapy, most notably immune checkpoint inhibitors (ICI). The motivation for combining FT and ICI in cancer management relies on the synergy between the two different therapies: FT complements ICI by reducing tumor burden, increasing objective response rate, and reducing side effects of ICI; ICI supplements FT by reducing local recurrence, controlling distal metastases, and providing long-term protection. This combinatorial strategy has shown promising results in preclinical study (since 2004) and the clinical trials (since 2011). Understanding the synergy calls for understanding the physics and biology behind the two different therapies with distinctive mechanisms of action. In this review, we introduce different types of energy-based FT by covering the biophysics of tissue-energy interaction and present the immunomodulatory properties of FT. We discuss the basis of cancer immunotherapy with the emphasis on ICI. We examine the approaches researchers have been using and the results from both preclinical models and clinical trials from our exhaustive literature research. Finally, the challenges of the combinatory strategy and opportunities of future research is discussed extensively.

Acute ATP loss during irreversible electroporation mediates caspase independent cell death

Irreversible electroporation (IRE) has been reported to variably cause apoptosis, necrosis, oncosis or pyroptosis. Intracellular ATP is a key substrate for apoptosis which is rapidly depleted during IRE, we sought to understand whether intracellular ATP levels is a determinant of the mode of cell death following IRE. A mouse bladder cancer cell line (MB49) was treated with electric fields while increasing the number of pulses at a fixed electric field strength, and pulse width. Cell proliferation and viability and ATP levels were measured at different timepoints post-treatment. Cell death was quantified with Annexin-V/Propidium Iodide staining. Caspase activity was measure with a fluorometric kit and western blotting. A pan-caspase (Z-VAD-FMK) inhibitor was used to assess the impact of signal inhibition. We found cell death following IRE was insensitive to caspase inhibition and was correlated with ATP loss. These findings were confirmed by cell death assays and measurement of changes in caspase expression on immunoblotting. This effect could not be rescued by ATP supplementation. Rapid and acute ATP loss during IRE interferes with caspase signaling, promoting necrosis. Cell necrosis from IRE is expected to be immunostimulatory and may be effective in cancer cells that carry mutated or defective apoptosis genes.

Irreversible Electroporation in Pancreatic Cancer-An Evolving Experimental and Clinical Method

Pancreatic cancer has no symptoms until the disease has advanced and is aggressive cancer with early metastasis. Up to now, the only curative treatment is surgical resection, which is possible in the early stages of the disease. Irreversible electroporation treatment offers new hope for patients with unresectable tumors. Irreversible electroporation (IRE) is a type of ablation therapy that has been explored as a potential treatment for pancreatic cancer. Ablation therapies involve the use of energy to destroy or damage cancer cells. IRE involves using high-voltage, low-energy electrical pulses to create resealing in the cell membrane, causing the cell to die. This review summarizes experiential and clinical findings in terms of the IRE applications. As was described, IRE can be a non-pharmacological approach (electroporation) or combined with anticancer drugs or standard treatment methods. The efficacy of irreversible electroporation (IRE) in eliminating pancreatic cancer cells has been demonstrated through both in vitro and in vivo studies, and it has been shown to induce an immune response. Nevertheless, further investigation is required to assess its effectiveness in human subjects and to comprehensively understand IRE's potential as a treatment option for pancreatic cancer.

Targeting pyroptosis in breast cancer: biological functions and therapeutic potentials on It

Pyroptosis is a lytic and inflammatory type of programmed cell death that is mediated by Gasdermin proteins (GSDMs). Attractively, recent evidence indicates that pyroptosis involves in the development of tumors and can serve as a new strategy for cancer treatment. Here, we present a basic knowledge of pyroptosis, and an overview of the expression patterns and roles of GSDMs in breast cancer. In addition, we further summarize the available evidence of pyroptosis in breast cancer progression and give insight into the clinical potential of applying pyroptosis in anticancer strategies for breast cancer. This review will deepen our understanding of the relationship between pyroptosis and breast cancer, and provide a novel potential therapeutic avenue for breast cancer.

Treatment of pancreatic cancer with irreversible electroporation and intratumoral CD40 antibody stimulates systemic immune responses that inhibit liver metastasis in an orthotopic model

BACKGROUND

Pancreatic cancer (PC) has a poor prognosis, and most patients present with either locally advanced or distant metastatic disease. Irreversible electroporation (IRE) is a non-thermal method of ablation used clinically in locally advanced PC, but most patients eventually develop distant recurrence. We have previously shown that IRE alone is capable of generating protective, neoantigen-specific immunity. Here, we aim to generate meaningful therapeutic immune effects by combining IRE with local (intratumoral) delivery of a CD40 agonistic antibody (CD40Ab).

METHODS

KPC46 organoids were generated from a tumor-bearing male KrasLSL-G12D-p53LSL-R172H-Pdx-1-Cre (KPC) mouse. Orthotopic tumors were established in the pancreatic tail of B6/129 F1J mice via laparotomy. Mice were randomized to treatment with either sham laparotomy, IRE alone, CD40Ab alone, or IRE followed immediately by CD40Ab injection. Metastatic disease and immune infiltration in the liver were analyzed 14 days postprocedure using flow cytometry and multiplex immunofluorescence imaging with spatial analysis. Candidate neoantigens were identified by mutanome profiling of tumor tissue for ex vivo functional analyses.

RESULTS

The combination of IRE+CD40 Ab improved median survival to greater than 35 days, significantly longer than IRE (21 days) or CD40Ab (24 days) alone (p<0.01). CD40Ab decreased metastatic disease burden, with less disease in the combination group than in the sham group or IRE alone. Immunohistochemistry of liver metastases revealed a more than twofold higher infiltration of CD8+T cells in the IRE+CD40 Ab group than in any other group (p<0.01). Multiplex immunofluorescence imaging revealed a 4-6 fold increase in the density of CD80+CD11c+ activated dendritic cells (p<0.05), which were spatially distributed throughout the tumor unlike the sham group, where they were restricted to the periphery. In contrast, CD4+FoxP3+ T-regulatory cells (p<0.05) and Ly6G+myeloid derived cells (p<0.01) were reduced and restricted to the tumor periphery in the IRE+CD40 Ab group. T-cells from the IRE+CD40 Ab group recognized significantly more peptides representing candidate neoantigens than did T-cells from the IRE or untreated control groups.

CONCLUSIONS

IRE can induce local tumor regression and neoantigen-specific immune responses. Addition of CD40Ab to IRE improved dendritic cell activation and neoantigen recognition, while generating a strong systemic antitumor T-cell response that inhibited metastatic disease progression.

Magic bubbles: utilizing histotripsy to modulate the tumor microenvironment and improve systemic anti-tumor immune responses

Focused Ultrasound (FUS) is emerging as a promising primary and adjunct therapy for the treatment of cancer. This includes histotripsy, which is a noninvasive, non-ionizing, non-thermal ultrasound guided ablation modality. As histotripsy has progressed from bench-to-bedside, it has become evident that this therapy has benefits beyond local tumor ablation. Specifically, histotripsy has the potential to shift the local tumor microenvironment from immunologically 'cold' to 'hot'. This is associated with the production of damage associated molecular patterns, the release of a selection of proinflammatory mediators, and the induction of inflammatory forms of cell death in cells just outside of the treatment zone. In addition to the induction of this innate immune response, histotripsy can also improve engagement of the adaptive immune system and promote systemic anti-tumor immunity targeting distal tumors and metastatic lesions. These tantalizing observations suggest that, in settings of widely metastatic disease burden, selective histotripsy of a limited number of accessible tumors could be a means of maximizing responsiveness to systemic immunotherapy. More work is certainly needed to optimize treatment strategies that best synergize histotripsy parameters with innate and adaptive immune responses. Likewise, rigorous clinical studies are still necessary to verify the presence and repeatability of these phenomena in human patients. As this technology nears regulatory approval for clinical use, it is our expectation that the insights and immunomodulatory mechanisms summarized in this review will serve as directional guides for rational clinical studies to validate and optimize the potential immunotherapeutic role of histotripsy tumor ablation.

High-Frequency Nanosecond Bleomycin Electrochemotherapy and its Effects on Changes in the Immune System and Survival

In this work, a time-dependent and time-independent study on bleomycin-based high-frequency nsECT (3.5 kV/cm × 200 pulses) for the elimination of LLC1 tumours in C57BL/6J mice is performed. We show the efficiency of nsECT (200 ns and 700 ns delivered at 1 kHz and 1 MHz) for the elimination of tumours in mice and increase of their survival. The dynamics of the immunomodulatory effects were observed after electrochemotherapy by investigating immune cell populations and antitumour antibodies at different timepoints after the treatment. ECT treatment resulted in an increased percentage of CD4⁺ T, splenic memory B and tumour-associated dendritic cell subsets. Moreover, increased levels of antitumour IgG antibodies after ECT treatment were detected. Based on the time-dependent study results, nsECT treatment upregulated PD 1 expression on splenic CD4⁺ Tr1 cells, increased the expansion of splenic CD8⁺ T, CD4⁺CD8⁺ T, plasma cells and the proportion of tumour-associated pro inflammatory macrophages. The Lin^- population of immune cells that was increased in the spleens and tumour after nsECT was identified. It was shown that nsECT prolonged survival of the treated mice and induced significant changes in the immune system, which shows a promising alliance of nanosecond electrochemotherapy and immunotherapy.

Issues and prospects of image-guided thermal ablation in the treatment of primary and metastatic lung tumors

The precise local minimally invasive or noninvasive treatment represents the important orientation for advancing the treatment of pulmonary malignant tumors. New local treatment methods have emerged as solutions to the shortcomings of minimally invasive or local treatment methods. Image-guided thermal ablation (IGTA) comes with the characteristics such as more accurate localization, less trauma, more definite efficacy, higher safety, stronger repeatability, fewer complications, and lower cost in treating lung tumors. This paper investigates the existing problems of IGTA in the treatment of lung tumors and puts forward the orientation of studies.

Lethal Electric Field Thresholds for Cerebral Cells With Irreversible Electroporation and H-FIRE Protocols: An In Vitro Three-Dimensional Cell Model Study

The lethal electric field (LEF) thresholds for three typical cerebral cells, including a malignant glioblastoma (GBM) cell line and two cell lines from the healthy blood-brain barrier (BBB), treated by irreversible electroporation (IRE) or high-frequency irreversible electroporation (H-FIRE) protocols were investigated in an in vitro three-dimensional (3D) cell model. A conventional IRE protocol (90 pulses, 1 Hz, and 100-μs pulse duration) and three novel H-FIRE protocols (1-3-1, 0.5-1-0.5, and 1-1-1) were used to treat the cerebral cells in both 3D single-cell and two-cell models. The electrical conductivity of the 3D cell model under different electric field strengths were characterized with the method of electrochemical impedance spectroscopy (EIS). Based on EIS, a numerical electrothermal model of electroporation was built for the determination of the LEF threshold with different protocols and temperature monitoring. Cell viability was assessed by fluorescence staining 6 h after the treatment. The results showed no thermal lethal effect on cells when these protocols were used. The LEF threshold for GBM cells was significantly lower than that of the healthy BBB cells. These results suggest the possibility of selective ablation of human cerebral GBM by IRE and H-FIRE treatments with no injury or reversible injury to healthy cells, and the potential use of IRE or H-FIRE for transient disruption of the BBB to allow chemotherapy to reach the tumor.

The role of pyroptosis and its crosstalk with immune therapy in breast cancer

Pyroptosis is a brand-new category of programmed cell death (PCD) that is brought on by multitudinous inflammasomes, which can recognize several stimuli to pilot the cleavage of and activate inflammatory cytokines like IL-18 and IL-1β is believed to have dual effects on the development of multiple cancers including breast cancer. However, pyroptosis has different effects on cancers depending on the type of tissues and their distinct heredity. Recently, the association between pyroptosis and breast cancer has received more and more attention, and it is thought that inducing pyroptosis could be used as a cancer treatment option. In addition, a great deal of evidence accumulating over the past decades has evinced the crosstalk between pyroptosis and tumor immunological therapy. Thus, a comprehensive summary combining the function of pyroptosis in breast cancer and antitumor immunity is imperative. We portray the prevalent knowledge of the multidimensional roles of pyroptosis in cancer and summarize the pyroptosis in breast cancer principally. Moreover, we elucidate the influence of inflammasomes and pyroptosis-produced cytokines on the tumor microenvironment (TME) of breast cancer. Taken together, we aim to provide a clue to harness pyroptosis rationally and apply it to augment immunotherapy efficiency for breast cancer.

Effect of pulsed field ablation on solid tumor cells and microenvironment

Pulsed field ablation can increase membrane permeability and is an emerging non-thermal ablation. While ablating tumor tissues, electrical pulses not only act on the membrane structure of cells to cause irreversible electroporation, but also convert tumors into an immune active state, increase the permeability of microvessels, inhibit the proliferation of pathological blood vessels, and soften the extracellular matrix thereby inhibiting infiltrative tumor growth. Electrical pulses can alter the tumor microenvironment, making the inhibitory effect on the tumor not limited to short-term killing, but mobilizing the collective immune system to inhibit tumor growth and invasion together.

BI 2536 induces gasdermin E-dependent pyroptosis in ovarian cancer

Background

The frequent emergence of drug resistance to chemotherapy is a major obstacle for the treatment of ovarian cancer. There is a need for novel drugs to fulfill this challenge. Pyroptosis-inducing drugs can inhibit tumor growth. However, their roles in ovarian cancer have not been demonstrated.

Methods

We tested the effectiveness of a novel drug, BI 2536, which we found in colorectal cancer. Cell proliferation, cell cycle, and drug-induced apoptosis and pyroptosis were tested. In vivo treatments were performed using a cell-derived xenograft model.

Results

BI 2536 significantly inhibited the proliferation of ovarian cancer cells and induced cell cycle arrest at the G2/M phases. After BI 2536 treatment, DNA fragmentation and PS exposure on the outside of apoptotic cells were detected. Moreover, the pyroptotic phenotype of ovarian cancer cells along with the release of LDH and HMGB1 were observed, indicating the leakage of cells. Western blot analysis verified that BI 2536 induced GSDME-mediated pyroptosis. Pyroptosis was abolished after additional treatment with Z-DEVD-FMK, a caspase-3 inhibitor. Thus, BI 2536 induced pyroptosis in ovarian cancer through the caspase-3/GSDME pathway. In vivo experiments further demonstrated the antitumoral effect and ability of BI 2536 to accumulate CD8⁺ T cells in ovarian cancer.

Conclusion

In this study, we identified BI 2536 as an effective anti-ovarian cancer drug that inhibits proliferation, arrests the cell cycle, induces apoptosis and pyroptosis, and leads to the accumulation of CD8⁺ T cells in tumor sites. Drug-induced pyroptosis may have promising prospects for reducing side effects and activating immune responses.

Activation of pyroptosis by specific organelle-targeting photodynamic therapy to amplify immunogenic cell death for anti-tumor immunotherapy

Pyroptosis, a unique lytic programmed cell death, inspired tempting implications as potent anti-tumor strategy in pertinent to its potentials in stimulating anti-tumor immunity for eradication of primary tumors and metastasis. Nonetheless, rare therapeutics have been reported to successfully stimulate pyroptosis. In view of the intimate participation of reactive oxygen species (ROS) in stimulating pyroptosis, we attempted to devise a spectrum of well-defined subcellular organelle (including mitochondria, lysosomes and endoplasmic reticulum)-targeting photosensitizers with the aim of precisely localizing ROS (produced from photosensitizers) at the subcellular compartments and explore their potentials in urging pyroptosis and immunogenic cell death (ICD). The subsequent investigations revealed varied degrees of pyroptosis upon photodynamic therapy (PDT) towards cancerous cells, as supported by not only observation of the distinctive morphological and mechanistic characteristics of pyroptosis, but for the first-time explicit validation from comprehensive RNA-Seq analysis. Furthermore, in vivo anti-tumor PDT could exert eradication of the primary tumors, more importantly suppressed the distant tumor and metastatic tumor growth through an abscopal effect, approving the acquirement of specific anti-tumor immunity as a consequence of pyroptosis. Hence, pyroptosis was concluded unprecedently by our proposed organelles-targeting PDT strategy and explicitly delineated with molecular insights into its occurrence and the consequent ICD.

Electroporation and Immunotherapy-Unleashing the Abscopal Effect

Simple Summary

Electrochemotherapy and irreversible electroporation are primarily used for treating patients with cutaneous and subcutaneous tumors and pancreatic cancer, respectively. Increasing numbers of studies have shown that the treatments may elicit an immune response in addition to eliminating the tumor cells. The purpose of this review is to give an in-depth introduction to the electroporation-induced immune response and the local and peripheral immune systems, and to describe the various studies investigating the combination of electroporation and immunotherapy. The review may help guide and inspire the design of future clinical trials investigating the potential synergy of electroporation and immunotherapy in cancer treatment.

Abstract

The discovery of electroporation in 1968 has led to the development of electrochemotherapy (ECT) and irreversible electroporation (IRE). ECT and IRE have been established as treatments of cutaneous and subcutaneous tumors and locally advanced pancreatic cancer, respectively. Interestingly, the treatment modalities have been shown to elicit immunogenic cell death, which in turn can induce an immune response towards the tumor cells. With the dawn of the immunotherapy era, the potential of combining ECT and IRE with immunotherapy has led to the launch of numerous studies. Data from the first clinical trials are promising, and new combination regimes might change the way we treat tumors characterized by low immunogenicity and high levels of immunosuppression, such as melanoma and pancreatic cancer. In this review we will give an introduction to ECT and IRE and discuss the impact on the immune system. Additionally, we will present the results of clinical and preclinical trials, investigating the combination of electroporation modalities and immunotherapy.

Combination of Metal-Phenolic Network-Based Immunoactive Nanoparticles and Bipolar Irreversible Electroporation for Effective Cancer Immunotherapy

To circumvent the limitations of conventional cancer immunotherapy, it is critical to prime antigen-presenting cells (APCs) to initiate the cancer-immune cycle. Here, the authors develop a metal-phenolic network (MPN)-based immunoactive nanoparticle in combination with irreversible electroporation (IRE) for an effective cancer immunotherapy. The MPN nanoparticles are synthesized by coordinating tannic acid with manganese (Mn) ions, and subsequent coating with CpG-oligodeoxynucleotides (CpG-ODNs) via hydrogen bonding. The CpG-ODN-coated Mn-phenolic network (CMP) nanoparticles are effectively internalized into macrophages, a type of APCs, and successfully trigger M1 polarization to promote release of proinflammatory cytokines. Notably, the CMP nanoparticles demonstrate an extended retention time period than the free CpG-ODN in the tumor. The tumor microenvironment tailored bipolar IRE, enhances the therapeutic efficacy by significantly broadening the ablation zone, which further increases immunogenic cell death (ICD). Ultimately, the simultaneous CMP nanoparticles and IRE treatment successfully inhibit tumor growth and prolong survival in a mouse tumor model. Thus, CMP nanoparticles are empowered with Mn and CpG-ODN immunomodulators and the tumor microenvironment tailored bipolar IRE will be a new tool for effective cancer immunotherapy to treat intractable malignancies.

Percutaneous Ablation of Hepatic Tumors at the Hepatocaval Confluence Using Irreversible Electroporation: A Preliminary Study

Background: Tumors at the hepatocaval confluence are difficult to treat, either surgically or ablatively. Methods: A retrospective longitudinal study on patients ineligible for thermal ablation who underwent computed tomography-guided IRE for hepatic tumors at the hepatocaval confluence was conducted. Factors analyzed included patient and tumor characteristics, IRE procedure details, treatment-related complications, and prognosis. Results: Between 2017 and 2021, 21 patients at our institute received percutaneous IRE. Of the 38 lesions, 21 were at the hepatocaval confluence. Complete ablation was achieved in all cases. Local and distant recurrence was observed in 4.8% (1/21) and 42.6% (9/21) of the ablated tumors, respectively. All postcava remained perfused at follow-up, except for 1 (4.8%) hepatic vein near the lesion found to be temporarily occluded and restored within 1 month. The ratio of the maximum diameter of ablation area at 1, 3, and 6 months post procedure compared to that immediately after IRE was 0.68 (0.50–0.84), 0.49 (0.27–0.61), and 0.38 (0.25–0.59), respectively. Progression-free survival of the patients with recurrence was 121 (range, 25–566) days. Four (19.0%) patients died at the end of follow-up with median overall survival of 451.5 (range, 25–716) days. Conclusions: IRE could be a safe and effective treatment for hepatic tumors at the hepatocaval confluence. This article provides valuable prognostic data; further clinical research is needed for better prognosis.

Muscle contractions and pain sensation accompanying high-frequency electroporation pulses

To minimize neuromuscular electrical stimulation during electroporation-based treatments, the replacement of long monophasic pulses with bursts of biphasic high-frequency pulses in the range of microseconds was suggested in order to reduce muscle contraction and pain sensation due to pulse application. This treatment modality appeared under the term high-frequency electroporation (HF-EP), which can be potentially used for some clinical applications of electroporation such as electrochemotherapy, gene electrotransfer, and tissue ablation. In cardiac tissue ablation, which utilizes irreversible electroporation, the treatment is being established as Pulsed Field Ablation. While the reduction of muscle contractions was confirmed in multiple in vivo studies, the reduction of pain sensation in humans was not confirmed yet, nor was the relationship between muscle contraction and pain sensation investigated. This is the first study in humans examining pain sensation using biphasic high-frequency electroporation pulses. Twenty-five healthy individuals were subjected to electrical stimulation of the tibialis anterior muscle with biphasic high-frequency pulses in the range of few microseconds and both, symmetric and asymmetric interphase and interpulse delays. Our results confirm that biphasic high-frequency pulses with a pulse width of 1 or 2 µs reduce muscle contraction and pain sensation as opposed to currently used longer monophasic pulses. In addition, interphase and interpulse delays play a significant role in reducing the muscle contraction and/or pain sensation. The study shows that the range of the optimal pulse parameters may be increased depending on the prerequisites of the therapy. However, further evaluation of the biphasic pulse protocols presented herein is necessary to confirm the efficiency of the newly proposed HF-EP.

Thermal shielding performance of self-healing hydrogel in tumor thermal ablation

Thermal ablation therapy is widely used in the surgical treatment of tumors. Clinically, normal saline is generally used as an insulator to protect adjacent tissues from local high-temperature burns caused by thermal ablation. However, the flow of saline causes fluid loss, requiring frequent injections and complex operation, which is easy to lead to complications such as secondary injury and hematoma. Here, a self-healing chitosan-PEG (CP) hydrogel was proposed as a protective medium to challenge the clinical preparations. Compared with saline and non-self-healing hydrogel F127, CP hydrogel exhibited outstanding thermal shielding performance in the thermal ablation of thyroid nodule in a Beagle dog model. The transient plane source (TPS) method is used to measure thermal properties, including thermal conductivity, thermal diffusivity and specific heat capacity. The thermal shielding mechanism and clinical advantages including operability, biodegradability, and biological safety of self-healing hydrogel are then revealed in-depth. Therefore, self-healing hydrogel can achieve much better thermal management in tumor thermal ablation.