Electrochemotherapy with anti-PD-1 treatment induced durable complete response in heavily pretreated metastatic melanoma patient

Electrochemotherapy combined with immunotherapy - a promising potential in the treatment of cancer

Electrochemotherapy is a novel, locoregional therapy that is used to treat cutaneous and deep-seated tumors. The electric pulses used in electrochemotherapy increase the permeability of the cell membranes of the target lesion and thus enhance the delivery of low-permeant cytotoxic drugs to the cells, leading to their death. It has also been postulated that electrochemotherapy acts as an in situ vaccination by inducing immunogenic cell death. This in turn leads to an enhanced systemic antitumor response, which could be further exploited by immunotherapy. However, only a few clinical studies have investigated the role of combined treatment in patients with melanoma, breast cancer, hepatocellular carcinoma, and cutaneous squamous cell carcinoma. In this review, we therefore aim to review the published preclinical evidence on combined treatment and to review clinical studies that have investigated the combined role of electrochemotherapy and immunotherapy.

Optimal Dosing and Patient Selection for Electrochemotherapy in Solid Abdominal Organ and Bone Tumors

The primary aim of this study was to analyze studies that use electrochemotherapy (ECT) in "deep-seated" tumors in solid organs (liver, kidney, bone metastasis, pancreas, and abdomen) and understand the similarities between patient selection, oncologic selection, and use of new procedures and technology across the organ systems to assess response rates. A literature search was conducted using the term "Electrochemotherapy" in the title field using publications from 2017 to 2023. After factoring in inclusion and exclusion criteria, 29 studies were analyzed and graded based on quality in full. The authors determined key patient and oncologic selection characteristics and ECT technology employed across organ systems that yielded overall responses, complete responses, and partial responses of the treated tumor. It was determined that key selection factors included: the ability to be administered bleomycin, life expectancy greater than three months, unrespectability of the lesion being treated, and a later stage, more advanced cancer. Regarding oncologic selection, all patient cohorts had received chemotherapy or surgery previously but had disease recurrence, making ECT the only option for further treatment. Lastly, in terms of the use of technology, the authors found that studies with better response rates used the ClinporatorTM and updated procedural guidelines by SOP. Thus, by considering patient, oncologic, and technology selection, ECT can be further improved in treating lesions in solid organs.

Electroporation in Head-and-Neck Cancer: An Innovative Approach with Immunotherapy and Nanotechnology Combination

Squamous cell carcinoma is the most common malignancy that arises in the head-and-neck district. Traditional treatment could be insufficient in case of recurrent and/or metastatic cancers; for this reason, more selective and enhanced treatments are in evaluation in preclinical and clinical trials to increase in situ concentration of chemotherapy drugs promoting a selectively antineoplastic activity. Among all cancer treatment types (i.e., surgery, chemotherapy, radiotherapy), electroporation (EP) has emerged as a safe, less invasive, and effective approach for cancer treatment. Reversible EP, using an intensive electric stimulus (i.e., 1000 V/cm) applied for a short time (i.e., 100 μs), determines a localized electric field that temporarily permealizes the tumor cell membranes while maintaining high cell viability, promoting cytoplasm cell uptake of antineoplastic agents such as bleomycin and cisplatin (electrochemotherapy), calcium (Ca²⁺ electroporation), siRNA and plasmid DNA (gene electroporation). The higher intracellular concentration of antineoplastic agents enhances the antineoplastic activity and promotes controlled tumor cell death (apoptosis). As secondary effects, localized EP (i) reduces the capillary blood flow in tumor tissue ("vascular lock"), lowering drug washout, and (ii) stimulates the immune system acting against cancer cells. After years of preclinical development, electrochemotherapy (ECT), in combination with bleomycin or cisplatin, is currently one of the most effective treatments used for cutaneous metastases and primary skin and mucosal cancers that are not amenable to surgery. To reach this clinical evidence, in vitro and in vivo models were preclinically developed for evaluating the efficacy and safety of ECT on different tumor cell lines and animal models to optimize dose and administration routes of drugs, duration, and intensity of the electric field. Improvements in reversible EP efficacy are under evaluation for HNSCC treatment, where the focus is on the development of a combination treatment between EP-enhanced nanotechnology and immunotherapy strategies.

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.

Electrical Stimulation for Immune Modulation in Cancer Treatments

Immunotherapy is becoming a very common treatment for cancer, using approaches like checkpoint inhibition, T cell transfer therapy, monoclonal antibodies and cancer vaccination. However, these approaches involve high doses of immune therapeutics with problematic side effects. A promising approach to reducing the dose of immunotherapeutic agents given to a cancer patient is to combine it with electrical stimulation, which can act in two ways; it can either modulate the immune system to produce the immune cytokines and agents in the patient's body or it can increase the cellular uptake of these immune agents via electroporation. Electrical stimulation in form of direct current has been shown to reduce tumor sizes in immune-competent mice while having no effect on tumor sizes in immune-deficient mice. Several studies have used nano-pulsed electrical stimulations to activate the immune system and drive it against tumor cells. This approach has been utilized for different types of cancers, like fibrosarcoma, hepatocellular carcinoma, human papillomavirus etc. Another common approach is to combine electrochemotherapy with immune modulation, either by inducing immunogenic cell death or injecting immunostimulants that increase the effectiveness of the treatments. Several therapies utilize electroporation to deliver immunostimulants (like genes encoded with cytokine producing sequences, cancer specific antigens or fragments of anti-tumor toxins) more effectively. Lastly, electrical stimulation of the vagus nerve can trigger production and activation of anti-tumor immune cells and immune reactions. Hence, the use of electrical stimulation to modulate the immune system in different ways can be a promising approach to treat cancer.

New era of electrochemotherapy in treatment of liver tumors in conjunction with immunotherapies

Electrochemotherapy is a local ablative therapy that increases the cytotoxicity of either bleomycin or cisplatin by applying electric pulses (electroporation) to tumors. It has already been widely used throughout Europe for the treatment of various types of human and veterinary cutaneous tumors, with an objective response rate ranging from 70%-90%, depending on the tumor histotype. Recently, electrochemotherapy was introduced for the treatment of primary liver tumors, such as hepatocellular carcinoma (HCC). The complete response rate was 85% per treated lesion, with a durable response. Therefore, electrochemotherapy could become a treatment of choice for HCC, especially after achieving a transition from an open surgery approach to a percutaneous approach that uses dedicated electrodes. Electrochemotherapy elicits a local immune response and can be considered an in situ vaccination. HCC, among others, is a potentially immunogenic tumor; thus, electrochemotherapy could boost adjuvant immunotherapy to achieve a better and longer-lasting antitumor response. Therefore, therapeutic strategies that combine electrochemotherapy with immune checkpoint inhibitors or adjuvant treatment with cytokines are indicated for HCC. Immunogene therapy using electroporation as a delivery system for plasmid DNA coding for interleukin-12 is a highly promising approach. This electroporation approach has shown efficacy in preclinical settings and veterinary oncology and is awaiting translation for the treatment of liver tumors, i.e., HCC.

Electrochemotherapy as a Trigger to Overcome Primary Resistance to Anti-PD-1 Treatment: A Case Report of Melanoma of the Scalp

Background

Immunotherapy with immune checkpoint inhibitors is one of the main therapies for advanced melanoma. Nevertheless, albeit remarkable, immunotherapy results are still unsatisfactory as more than half of patients progress, and resistance to treatment still has a dramatic impact on clinical outcomes. Local treatments such as radiotherapy or electrochemotherapy (ECT), in addition to local control with palliative intent, have been shown to release tumoral neoantigens that can stimulate a robust systemic antitumor immune response.

Case Presentation

We report the case of a patient with multiple nodular melanoma lesions of the scalp initially treated with local ECT. Soon after the procedure, multiple new lesions appeared close to the treated ones, therefore the patient started a systemic treatment with the anti-PD-1 nivolumab. The lesions of the scalp did not respond to immunotherapy, presenting a loco-regional spreading. To control the bleeding and painful lesions, we performed a second ECT, while continuing systemic immunotherapy. The treated lesions responded to the second procedure, while the other lesions continued progressing in number and dimension. Unexpectedly, after 2 months from the second ECT, the patient presented a progressive shrinkage of both treated and untreated lesions until complete remission. Concomitantly, he developed immune-related adverse events including grade 4 thyroid toxicity, grade 2 vitiligo-like depigmentation and grade 2 pemphigoid. At present, after 18 months from the first ECT and 14 months from the starting of anti-PD-1 immunotherapy, the patient is in good clinical condition and complete remission of disease still persists.

Conclusion

This case highlights the potential role of ECT in increasing tumor immunogenicity and consequently in inducing a powerful immune response overcoming primary resistance to checkpoint inhibitor immunotherapy.

Combination of Pembrolizumab with Electrochemotherapy in Cutaneous Metastases from Melanoma: A Comparative Retrospective Study from the InspECT and Slovenian Cancer Registry

Simple Summary

Electrochemotherapy (ECT) combines a cytotoxic agent with locally applied electric pulses to enhance its antitumor effect. Over the last 15 years, ECT has been safely applied to patients with skin metastases in combination with other oncologic treatments and, more recently, with systemic immunotherapy. In this study, we aimed to investigate the effectiveness of ECT in combination with pembrolizumab. We compared patient outcomes after the following treatments: (a) pembrolizumab, (b) pembrolizumab and ECT, and (c) ECT alone. The combined application of pembrolizumab and ECT was safe and more efficacious in preventing further growth of cutaneous metastases than pembrolizumab alone. The patients treated with pembrolizumab and ECT experienced lower disease progression rates and longer survival than those who received pembrolizumab. ECT may boost the effect of pembrolizumab by acting as an in situ vaccination against cancer cells. Further studies are required to confirm these findings.

Abstract

Electrochemotherapy (ECT) is an effective locoregional therapy for cutaneous melanoma metastases and has been safely combined with immune checkpoint inhibitors in preliminary experiences. Since ECT is known to induce immunogenic cell death, its combination with immune checkpoint inhibitors might be beneficial. In this study, we aimed to investigate the effectiveness of ECT on cutaneous melanoma metastases in combination with pembrolizumab. We undertook a retrospective matched cohort analysis of stage IIIC–IV melanoma patients, included in the International Network for sharing practices of ECT (InspECT) and the Slovenian Cancer Registry. We compared the outcome of patients who received the following treatments: (a) pembrolizumab alone, (b) pembrolizumab plus ECT, and (c) ECT. The groups were matched for age, sex, performance status, and size of skin metastases. The local objective response rate (ORR) was higher in the pembrolizumab-ECT group than in the pembrolizumab group (78% and 39%, p < 0.001). The 1 year local progression-free survival (LPFS) rates were 86% and 51% (p < 0.001), and the 1 year systemic PFS rates were 64% and 39%, respectively (p = 0.034). The 1 year overall survival (OS) rates were 88% and 64%, respectively (p = 0.006). Our results suggest that skin-directed therapy with ECT improves superficial tumor control in melanoma patients treated with pembrolizumab. Interestingly, we observed longer PFS and OS in the pembrolizumab-ECT group than in the pembrolizumab group. These findings warrant prospective confirmation.

Clinical Applications and Immunological Aspects of Electroporation-Based Therapies

Reversible electropermeabilization (RE) is an ultrastructural phenomenon that transiently increases the permeability of the cell membrane upon application of electrical pulses. The technique was described in 1972 by Neumann and Rosenheck and is currently used in a variety of applications, from medicine to food processing. In oncology, RE is applied for the intracellular transport of chemotherapeutic drugs as well as the delivery of genetic material in gene therapies and vaccinations. This review summarizes the physical changes of the membrane, the particularities of bleomycin, and the immunological aspects involved in electrochemotherapy and gene electrotransfer, two important EP-based cancer therapies in human and veterinary oncology.

Electrochemotherapy in the Treatment of Head and Neck Cancer: Current Conditions and Future Directions

Simple Summary

Electrochemotherapy (ECT) was first introduced in the late 1980s and was initially used mainly on cutaneous tumors. It has now evolved into a clinically verified treatment approach. Thanks to its high feasibility, it has been extended to treating mucosal and deep-seated tumors, including head and neck cancer (HNC) and in heavily pretreated settings. This review describes current knowledge and data on the use of ECT in various forms of HNCs across different clinical settings, with attention to future clinical and research perspectives.

Abstract

Despite recent advances in the development of chemotherapeutic drug, treatment for advanced cancer of the head and neck cancer (HNC) is still challenging. Options are limited by multiple factors, such as a prior history of irradiation to the tumor site as well as functional limitations. Against this background, electrochemotherapy (ECT) is a new modality which combines administration of an antineoplastic agent with locally applied electric pulses. These pulses allow the chemotherapeutic drug to penetrate the intracellular space of the tumor cells and thereby increase its cytotoxicity. ECT has shown encouraging efficacy and a tolerable safety profile in many clinical studies, including in heavily pre-treated HNC patients, and is considered a promising strategy. Efforts to improve its efficacy and broaden its application are now ongoing. Moreover, the combination of ECT with recently developed novel therapies, including immunotherapy, represented by immune checkpoint inhibitor (ICI)s, has attracted attention for its potent theoretical rationale. More extensive, well-organized clinical studies and timely updating of consensus guidelines will bring this hopeful treatment to HNC patients under challenging situations.

Biological factors of the tumour response to electrochemotherapy: Review of the evidence and a research roadmap

The beneficial effects of electrochemotherapy (ECT) for superficial tumours and, more recently, deep-seated malignancies in terms of local control and quality of life are widely accepted. However, the variability in responses across histotypes needs to be explored. Currently, patient selection for ECT is based on clinical factors (tumour size, histotype, and exposure to previous oncological treatments), whereas there are no biomarkers to predict the response to treatment. In this field, two major areas of investigation can be identified, i.e., tumour cell characteristics and the tumour microenvironment (vasculature, extracellular matrix, and immune infiltrate). For each of these areas, we describe the current knowledge and discuss how to foster further investigation. This review aims to provide a summary of the currently used guiding clinical factors and delineates a research roadmap for future studies to identify putative biomarkers of response to ECT. These biomarkers may allow researchers to improve ECT practice by customising treatment parameters, manipulating the tumour and its microenvironment, and exploring novel therapeutic combinations.

Addressing resistance to immune checkpoint inhibitor therapy: an urgent unmet need

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of various cancers by reversing the immunosuppressive mechanisms employed by tumors to restore anticancer immunity. Although ICIs have demonstrated substantial clinical efficacy, patient response can vary in depth and duration, and many do not respond at all or eventually develop resistance. ICI resistance mechanisms can be tumor-intrinsic, related to the tumor microenvironment or patient-specific factors. Multiple resistance mechanisms may be present within one tumor subtype, or heterogeneity exists among patients with the same tumor type. Consequently, designing effective combination treatment strategies is challenging. This review will discuss ICI resistance mechanisms, and summarize findings from key preclinical and clinical trials of ICIs, to identify potential treatment strategies or pathways to overcome ICI resistance.

Boosting the Immune Response with the Combination of Electrochemotherapy and Immunotherapy: A New Weapon for Squamous Cell Carcinoma of the Head and Neck?

Simple Summary

Squamous cell carcinoma of the head and neck (SCCHN) represents a problem of utmost concern and, for many clinicians and surgeons, an enormous challenge. Currently, new generation immunotherapy which avails of check point inhibitors, namely molecules capable of restoring the host’s immune system strongly depressed by the presence of tumor cells, is gaining increasing importance. Nevertheless, immunotherapy alone is not always effective in some patients, in particular those having a bulky and highly symptomatic disease. These last require the addition of locoregional strategies able to reduce the tumor mass and to assist immunotherapy in producing its effect. Electrochemotherapy (ECT) is a strategy able to associate the electroporation of tumor cells and the simultaneous administration of antineoplastic drugs, so as to concentrate the latter directly in the tumor site. The combination of ECT and immunotherapy could be very effective particularly in patients having a bulky/highly symptomatic SCCHN.

Abstract

Head and neck squamous cell carcinomas (SCCHN) are not rare malignancies and account for 7% of all solid tumors. Prognosis of SCCHN patients strongly depends on tumor extension, site of onset, and genetics. Advanced disease (recurrent/metastatic) is associated with poor prognosis, with a median overall survival of 13 months. In these patients, immunotherapy may represent an interesting option of treatment, given the good results reached by check-point inhibitors in clinical practice. Nevertheless, only a minor number of patients with advanced disease respond to immunotherapy, and, disease progressions/hyper-progressions are common. The latter could be a very difficult issue, especially in patients having a wide and highly symptomatic head/neck mass. Given the potentiality to boost the immune response of some local modalities, such as electrochemotherapy, a possible future approach may take into account the combination of electrochemotherapy and immunotherapy to treat patients affected by SCCHN, suffering from symptomatic lesions that need rapid debulking.

Electrochemotherapy of superficial tumors - Current status:: Basic principles, operating procedures, shared indications, and emerging applications

Treatment of superficial tumors with electrochemotherapy (ECT) has shown a steep rise over the past decade and indications range from skin cancers to locally advanced or metastatic neoplasms. Based on reversible electroporation, which is a physical method to achieve transient tumor cell membrane permeabilization by means of short electric pulses, ECT increases cellular uptake of bleomycin and cisplatin and their cytotoxicity by 8,000- and 80-fold, respectively. Standard operating procedures were established in 2006 and updated in 2018. Ease of administration, patient tolerability, efficacy across histotypes, and repeatability are peculiar advantages, which make standard ECT (ie, ECT using fixed-geometry electrodes) a reliable option for controlling superficial tumor growth locally and preventing their morbidity. Consolidated indications include superficial metastatic melanoma, breast cancer, head and neck skin tumors, nonmelanoma skin cancers, and Kaposi sarcoma. In well-selected patients with oropharyngeal cancers, ECT ensures appreciable symptom control. Emerging applications include skin metastases from visceral or hematological malignancies, vulvar cancer, and some noncancerous skin lesions (keloids and capillary vascular malformations). Repeatability and integration with other oncologic therapies allow for consolidation of response and sustained tumor control. In this review, we present the basic principles of ECT, recently updated operating procedures, anesthesiological management, and provide a synthesis of the efficacy of standard ECT across histotypes.

Electrochemotherapy as palliative treatment in patients with advanced head and neck tumours: Outcome analysis in 93 patients treated in a single institution

PURPOSE

To describe outcomes of Electrochemotherapy as palliative treatment in patients with advanced head and neck (H&N) tumours.

METHODS

Ninety-three patients (120 treatment sessions) with H&N recurrent and/or metastatic neoplasm were treated. Treatment response was assessed 4 weeks after ECT with clinical examination and two months after the first evaluation with a CT scan of the H&N for deep lesions evaluation. The grade of bleeding and pain before, at the end of treatment and one week after ECT were evaluated.

RESULTS

Five percent of complete responses, 40% of partial responses were registered. Disease progression was seen in 20% of patients after the first ECT procedure, the remaining 34% of patients experienced stable disease. A good control of pain and bleeding was obtained, especially in patients with moderate symptoms before the treatment. No toxicities related to ECT were seen.

CONCLUSIONS

ECT is an interesting antitumoral therapy in advanced chemo and radio-refractory H&N neoplasms. ECT is able to reduce frequent symptoms, such as pain and bleeding, improving quality of life without damage to healthy tissue and with limited side effects. Moreover, ECT reduces hospitalization time and may contribute to an overall reduction in healthcare costs associated with advanced H&N cancers care.

Tumor microenvironment classification based on T-cell infiltration and PD-L1 in patients with mismatch repair-proficient and -deficient colorectal cancer

The classification of tumor microenvironments according to the presence or absence of tumor infiltrating lymphocytes (TILs) and programmed death ligand-1 (PD-L1) expression has been used to predict the efficacy of immune checkpoint inhibitor antibodies in several cancer types, not including colorectal cancer (CRC). The current study investigated the TIL/PD-L1 status of patients with CRC, particularly patients who presented as mismatch repair-proficient (pMMR) and mismatch repair-deficient (dMMR). A total of 243 patients with CRC were enrolled and defined as pMMR (121 patients) or dMMR (122 patients). Using Pearson's χ² test and multivariable multinomial logistic regression analysis, the associations between MMR status, TIL presence and PD-L1 expression were investigated, in addition to the association between TIL/PD-L1 status and clinicopathological features. The results demonstrated that the dMMR group more frequently exhibited TIL⁺ (85/122 vs. 61/121) and PD-L1⁺ (49/122 vs. 32/121) phenotypes compared with the pMMR group. PD-L1⁺ expression was identified in 42.4% of TIL⁺ cases in the dMMR group, while only 18.0% of TIL⁺ cases were PD-L1⁺ in the pMMR group. High programmed death-1 expression and dMMR status were revealed as two independent risk factors for TIL⁺ PD-L1⁺ status. In conclusion, compared with the pMMR group, the dMMR group was more likely to present with a TIL⁺ PD-L1⁺ status, which suggests that a TIL⁺ PD-L1⁺ tumor microenvironment may partly contribute to the improved response of dMMR patients to anti-PD-1/L1 therapy.

The use of electrochemotherapy in combination with immunotherapy in the treatment of metastatic melanoma: a focused review

Electrochemotherapy (ECT) is a treatment modality that combines low-dose chemotherapy with electroporation, thereby enhancing cytotoxicity. ECT was first utilized in the treatment of metastatic head and neck cancer. Today it is used as a local treatment for the cutaneous and subcutaneous metastases of a variety of cancers, including melanoma. In addition, recent evidence indicates that ECT in combination with immunotherapy can lead to a systemic tumor response. This review aims to summarize the efficacy of ECT in the treatment of metastatic melanoma, with a specific focus on the combination of ECT with immunotherapy.

Immune-checkpoint inhibitors in melanoma and kidney cancer: from sequencing to rational selection

Immune-checkpoint inhibitors (ICPIs), including antibodies against cytotoxic T-lymphocyte associated antigen 4 and programmed cell death protein 1, have been shown to induce durable complete responses in a proportion of patients in the first-line and refractory setting in advanced melanoma and renal cell carcinoma. In fact, there are several lines of both targeted agents and ICPI that are now feasible treatment options. However, survival in the metastatic setting continues to be poor and there remains a need for improved therapeutic approaches. In order to enhance patient selection for the most appropriate next line of therapy, better predictive biomarkers of responsiveness will need to be developed in tandem with technologies to identify mechanisms of ICPI resistance. Adaptive, biomarker-driven trials will drive this evolution. The combination of ICPI with specific chemotherapies, targeted therapies and other immuno-oncology (IO) drugs in order to circumvent ICPI resistance and enhance efficacy is discussed. Recent data support the role for both targeted therapies and ICPI in the adjuvant setting of melanoma and targeted therapies in the adjuvant setting for renal cell carcinoma, which may influence the consideration of treatment on subsequent relapse. Approaches to select the optimal treatment sequences for these patients will need to be refined.