Minimally Invasive Electrochemotherapy Procedure for Treating Nasal Duct Tumors in Dogs using a Single Needle Electrode

Novel tetrapolar single-needle electrode for electrochemotherapy in bone cavities: Modeling, design and validation

Electrochemotherapy is a cancer treatment in which local pulsed electric fields are delivered through electrodes. The effectiveness of the treatment depends on exposing the tumor to a threshold electric field. Electrode geometry plays an important role in the resulting electric field distribution, especially in hard-to-reach areas and deep-seated tumors. We designed and developed a novel tetrapolar single-needle electrode for proper treatment in bone cavities. In silico and in vitro experiments were performed to evaluate the electric field and electric current produced by the electrode. In addition, tomography images of a real case of nasal cavity tumor were segmented into a 3D simulation to evaluate the electrode performance in a bone cavity. The proposed electrode was validated and its operating range was set up to 650 V. In the nasal cavity tumor, we found that the electrode can produce a circular electric field of 3 mm with an electric current of 14.1 A at 500 V, which is compatible with electrochemotherapy standards and commercial equipment.

Evaluation of the safety and feasibility of electrochemotherapy with intravenous bleomycin as local treatment of bladder cancer in dogs

Local treatment of canine urothelial carcinoma (UC) of the bladder is a challenge. More than 90% of the cases invade the muscular layer, more than 50% develop on bladder sites with a difficult surgical approach and often requiring radical surgical procedures. This study aims to evaluate the safety and feasibility of electrochemotherapy (ECT) with intravenous bleomycin (BLM) as a local therapy for bladder UC. This prospective study included 21 dogs with spontaneous bladder UC. Regional/distant metastases and neoplastic infiltration of the serosa was considered the main exclusion criteria. We had no deaths during ECT or in the immediate postoperative period, and no suture dehiscence. Most dogs (19/21) developed mild adverse effects, whereas two dogs developed ureteral stenosis. Complete response (CR) was achieved in 62% of the cases (13/21), while partial response (PR) was achieved in 24% (5/21). The median survival and disease-free survival times were 284 and 270 days, respectively. Overall survival was significantly better in the dogs who achieved a CR. In conclusion, ECT was well-tolerated in dogs with UC, demonstrating its safety and feasibility. These data pave the way for new studies aimed at evaluating the effectiveness of ECT in canine bladder UC as a translational model for human disease.

Electrochemotherapy: An Alternative Strategy for Improving Therapy in Drug-Resistant SOLID Tumors

Simple Summary

Chemotherapy is becoming an increasingly difficult antitumor therapy to practice due to the multiple mechanisms of drug resistance. To overcome the problem, it is possible to use alternative techniques, such as electrochemotherapy, which involves the simultaneous administration of the electrical pulse (electroporation) and the treatment with the drug in order to improve the effectiveness of the drug against the tumor. Electroporation has improved the efficacy of some chemotherapeutic agents, such bleomycin, cisplatin, mitomycin C, and 5-fluorouracil. The results of in vitro, veterinary, and clinical oncology studies are promising on various cancers, such as metastatic melanoma. The purpose of this review is to give an update on the state of the art of electrochemotherapy against the main solid tumors in the preclinical, clinical, and veterinary field.

Abstract

Electrochemotherapy (ECT) is one of the innovative strategies to overcome the multi drug resistance (MDR) that often occurs in cancer. Resistance to anticancer drugs results from a variety of factors, such as genetic or epigenetic changes, an up-regulated outflow of drugs, and various cellular and molecular mechanisms. This technology combines the administration of chemotherapy with the application of electrical pulses, with waveforms capable of increasing drug uptake in a non-toxic and well tolerated mechanical system. ECT is used as a first-line adjuvant therapy in veterinary oncology, where it improves the efficacy of many chemotherapeutic agents by increasing their uptake into cancer cells. The chemotherapeutic agents that have been enhanced by this technique are bleomycin, cisplatin, mitomycin C, and 5-fluorouracil. After their use, a better localized control of the neoplasm has been observed. In humans, the use of ECT was initially limited to local palliative therapy for cutaneous metastases of melanoma, but phase I/II studies are currently ongoing for several histotypes of cancer, with promising results. In this review, we described the preclinical and clinical use of ECT on drug-resistant solid tumors, such as head and neck squamous cell carcinoma, breast cancer, gynecological cancer and, finally, colorectal cancer.

Veterinary Guidelines for Electrochemotherapy of Superficial Tumors

Electrochemotherapy (ECT) consists in the application of electric pulses to increase chemotherapeutic drug intake (bleomycin, cisplatin, or calcium) into the tumor cells. It has become a very valuable treatment option in veterinary oncology. It is an effective and safe treatment modality, which is not only beneficial as a palliative treatment, but also for a curative approach. Performing the treatment adequately will ensure the best results possible, in the minimum number of sessions, and reduce complications. Usually, only one session is enough to achieve excellent results, but the treatment can be repeated. Several sessions can be necessary in the case of incompletely treated or very extended lesions, as well as in the occurrence of new lesions. ECT is effective for superficial or oral tumors of any histology that are accessible to the electrodes. Intravenous bleomycin is the preferred drug and route of administration, leaving other ways of administration and drugs for selected cases. The guidelines presented here are destined to veterinarians who want to develop their understanding of the basis of ECT and wish to perform it adequately and effectively. In this paper, we also discuss common problems and how to solve them, and we include practical tips to improve the treatment results based on common questions and mistakes of beginner users.

Electrochemotherapy treatment safety under parallel needle deflection

Electrochemotherapy is a selective electrical-based cancer treatment. A thriving treatment depends on the local electric field generated by pairs of electrodes. Electrode damage as deflection can directly affect this treatment pillar, the distribution of the electric field. Mechanical deformations such as tip misshaping and needle deflection are reported with needle electrode reusing in veterinary electrochemotherapy. We performed in vitro and in silico experiments to evaluate potential problems with ESOPE type II electrode deflection and potential treatment pitfalls. We also investigated the extent to which the electric currents of the electroporation model can describe deflection failure by comparing in vitro with the in silico model of potato tuber (Solanum tuberosum). The in silico model was also performed with the tumor electroporation model, which is more conductive than the vegetal model. We do not recommend using deflected electrodes. We have found that a deflection of ± 2 mm is unsafe for treatment. Inward deflection can cause dangerous electrical current levels when treating a tumor and cannot be described with the in silico vegetal model. Outward deflection can cause blind spots in the electric field.

New Perspectives for Eye-Sparing Treatment Strategies in Primary Uveal Melanoma

Simple Summary

Uveal melanoma is the most common intraocular cancer. The current eye-sparing treatment options include mostly plaque brachytherapy. However, the effectiveness of these methods is still unsatisfactory. In this article, we review several possible new treatment options. These methods may be based on the physical destruction of the cancerous cells by applying ultrasounds. Another approach may be based on improving the penetration of the anti-cancer agents. It seems that the most promising technologies from this group are based on enhancing drug delivery by applying electric current. Finally, new advanced nanoparticles are developed to combine diagnostic imaging and therapy (i.e., theranostics). However, these methods are mostly at an early stage of development. More advanced studies on experimental animals and clinical trials would be needed to introduce some of these techniques to routine clinical practice.

Abstract

Uveal melanoma is the most common intraocular malignancy and arises from melanocytes in the choroid, ciliary body, or iris. The current eye-sparing treatment options include surgical treatment, plaque brachytherapy, proton beam radiotherapy, stereotactic photon radiotherapy, or photodynamic therapy. However, the efficacy of these methods is still unsatisfactory. This article reviews several possible new treatment options and their potential advantages in treating localized uveal melanoma. These methods may be based on the physical destruction of the cancerous cells by applying ultrasounds. Two examples of such an approach are High-Intensity Focused Ultrasound (HIFU)—a promising technology of thermal destruction of solid tumors located deep under the skin and sonodynamic therapy (SDT) that induces reactive oxygen species. Another approach may be based on improving the penetration of anti-cancer agents into UM cells. The most promising technologies from this group are based on enhancing drug delivery by applying electric current. One such approach is called transcorneal iontophoresis and has already been shown to increase the local concentration of several different therapeutics. Another technique, electrically enhanced chemotherapy, may promote drug delivery from the intercellular space to cells. Finally, new advanced nanoparticles are developed to combine diagnostic imaging and therapy (i.e., theranostics). However, these methods are mostly at an early stage of development. More advanced and targeted preclinical studies and clinical trials would be needed to introduce some of these techniques to routine clinical practice.

A Retrospective Multicentric Study of Electrochemotherapy in the Treatment of Feline Nasal Planum Squamous Cell Carcinoma

Feline squamous cell carcinoma (SCC) is currently treated with surgery, radiation therapy and electrochemotherapy (ECT). Both the efficacy and/or safety of ECT were evaluated as a sole therapy with bleomycin to treat feline nasal planum SCC (npSCC). Sixty-one cats were enrolled. Local treatment response was evaluated as complete remission (CR), partial remission (PR) or stable disease (SD). Recurrence rate (RR), disease-free interval (DFI) and progression free survival (PFS) were calculated. A six-point scale was used for ECT toxicity. The median tumor size was 1.5 cm. CR was achieved in 65.6% of cases, PR in 31.1% and SD in 3.3%. The overall response rate was 96.7%, RR was 22.5%, median DFI was 136 days, and median PFS was 65.5 days. ECT toxicity was ≤2 in 51% of cats. Tumor recurrence/progression (p = 0.014) and local treatment response (PR: p < 0.001; SD: p < 0.001) influenced survival time. Cats with toxicity >2 showed a higher probability of tumor recurrence/progression. Tumor-related death was higher in cats with PR (p < 0.001) and recurrence/progression (p = 0.002), in ECT treatment with 1 Hz (p = 0.035) and 1200 V/cm (p = 0.011) or 1300 V/cm (p = 0.016). Tumor size influenced local treatment response (p = 0.008) and toxicity (p < 0.001). ECT is an effective treatment for feline npSCCs and should be considered as the first-line procedure for low-stage tumors.

Clinical Veterinary Boron Neutron Capture Therapy (BNCT) Studies in Dogs with Head and Neck Cancer: Bridging the Gap between Translational and Clinical Studies

Simple Summary

Boron Neutron Capture Therapy (BNCT) is a treatment for cancer based on the selective accumulation in tumor of boron compounds, followed by external irradiation with neutrons. The interaction between boron-10 and a neutron gives rise to very energetic particles that travel only a very short distance (approximately the diameter of a cell) and are lethal for the cell. In this way, BNCT damages tumor tissue selectively while preserving normal tissue. BNCT has proved effective to treat certain tumors in clinical trials worldwide, with room for improvement. Our group has worked on animal models to improve the efficacy of BNCT, in particular for head and neck cancer. Herein we performed clinical veterinary BNCT studies in five terminal dog patients with head and neck cancer with no other therapeutic option. In all cases we observed partial tumor response, clinical benefit, and extension of estimated survival time at recruitment with excellent quality of life. Toxicity associated to the treatment was mild/moderate and reversible. These studies contribute towards preparation for clinical BNCT trials for head and neck cancer in Argentina and suggest a potential role for BNCT in veterinary medicine.

Abstract

Translational Boron Neutron Capture Therapy (BNCT) studies performed by our group and clinical BNCT studies worldwide have shown the therapeutic efficacy of BNCT for head and neck cancer. The present BNCT studies in veterinary patients with head and neck cancer were performed to optimize the therapeutic efficacy of BNCT, contribute towards exploring the role of BNCT in veterinary medicine, put in place technical aspects for an upcoming clinical trial of BNCT for head and neck cancer at the RA-6 Nuclear Reactor, and assess the feasibility of employing the existing B2 beam to treat large, deep-seated tumors. Five dogs with head and neck cancer with no other therapeutic option were treated with two applications of BNCT mediated by boronophenyl-alanine (BPA) separated by 3–5 weeks. Two to three portals per BNCT application were used to achieve a potentially therapeutic dose over the tumor without exceeding normal tissue tolerance. Clinical and Computed Tomography results evidenced partial tumor control in all cases, with slight-moderate mucositis, excellent life quality, and prolongation in the survival time estimated at recruitment. These exploratory studies show the potential value of BNCT in veterinary medicine and contribute towards initiating a clinical BNCT trial for head and neck cancer at the RA-6 clinical facility.

Electroporation-Based Treatments in Small Animal Veterinary Oral and Maxillofacial Oncology

Electroporation is a method of inducing an increase in permeability of the cell membrane through the application of an electric field and can be used as a delivery method for introducing molecules of interest (e.g., chemotherapeutics or plasmid DNA) into cells. Electroporation-based treatments (i.e., electrochemotherapy, gene electrotransfer, and their combinations) have been shown to be safe and effective in veterinary oncology, but they are currently mostly recommended for the treatment of those solid tumors for which clients have declined surgery and/or radiotherapy. Published data show that electroporation-based treatments are also safe, simple, fast and cost-effective treatment alternatives for selected oral and maxillofacial tumors, especially small squamous cell carcinoma and malignant melanoma tumors not involving the bone in dogs. In these patients, a good local response to treatment is expected to result in increased survival time with good quality of life. Despite emerging evidence of the clinical efficacy of electroporation-based treatments for oral and maxillofacial tumors, further investigation is needed to optimize treatment protocols, improve clinical data reporting and better understand the mechanisms of patients' response to the treatment.

Electroporation as the Immunotherapy Strategy for Cancer in Veterinary Medicine: State of the Art in Latin America

Electroporation is a technology that increases cell membrane permeability by the application of electric pulses. Electrochemotherapy (ECT), the best-known application of electroporation, is a very effective local treatment for tumors of any histology in human and veterinary medicine. It induces a local yet robust immune response that is responsible for its high effectiveness. Gene electrotransfer (GET), used in research to produce a systemic immune response against cancer, is another electroporation-based treatment that is very appealing for its effectiveness, low cost, and simplicity. In this review, we present the immune effect of electroporation-based treatments and analyze the results of the vast majority of the published papers related to immune response enhancement by gene electrotransfer in companion animals with spontaneous tumors. In addition, we present a brief history of the initial steps and the state of the art of the electroporation-based treatments in Latin America. They have the potential to become an essential form of immunotherapy in the region. This review gives insight into the subject and helps to choose promising research lines for future work; it also helps to select the adequate treatment parameters for performing a successful application of this technology.

Electrochemotherapy in treatment of canine oral malignant melanoma and factors influencing treatment outcome

Background

Oral malignant melanoma is the most common, but aggressive oral cancer in dogs with poor prognosis. Electrochemotherapy (ECT) has therapeutic potential in such tumors as effective local treatment. Therefore, the aim of this prospective clinical study was to evaluate treatment effectiveness of ECT in as first line treatment for canine oral malignant melanoma, and search for factors influencing treatment outcome.

Methods

Sixty-seven canines with primary oral malignant melanoma, non-candidates for first-line therapy, were enrolled. All dogs received ECT and follow-up exams for the span of two years.

Results

Based on RECIST criteria, the objective response rate was 100%, 89.5%, 57.7%, and 36.4%, in stage I, II, III and IV, respectively. Only patients in stage I, II and III with partial or complete response improved their quality of life. The median time to progression was 11, 7, 4 and 4 months, and median survival time after the treatment was 16.5, 9.0, 7.5 and 4.5 months, for patients in stage I, II, III and IV, respectively. Significantly better was local response in stage I and II disease (p = 0.0013), without the bone involvement (p = 0.043)

Conclusions

Electrochemotherapy is effective local treatment of oral canine malignant melanoma when no alternative treatment is available. Better response is expected in stage I and II patients with tumors without bone involvement.

Recent Advances in Electrochemotherapy

Electrochemotherapy is gaining recognition as an effective local therapy that uses systemically or intratumorally injected bleomycin or cisplatin with electroporation as a delivery system that brings drugs into the cells to exert their cytotoxic effects. Preclinical work is still ongoing, testing new drugs, seeking the best treatment combination with other treatment modalities, and exploring new sets of pulses for effective tissue electroporation. The applications of electrochemotherapy are being fully exploited in veterinary oncology, where electrochemotherapy, because of its simple execution, has a relatively good cost-benefit ratio and is used in the treatment of cutaneous tumors. In human oncology, electrochemotherapy is fully recognized as a local therapy for cutaneous tumors and metastases. Its effectiveness is being explored in combination with immunomodulatory drugs. However, the development of electrochemotherapy is directed into the treatment of deep-seated tumors with a percutaneous approach. Because of the vast number of reports, this review discusses the articles published in the past 5 years.

Computer simulation of commercial conductive gels and their application to increase the safety of electrochemotherapy treatment

Electrochemotherapy (ECT) exploits the phenomenon of electroporation, which is the increase of cell permeability through the application of an electrical field. This technique is applied in medical centers in Europe and in veterinary clinics in Europe, Brazil, and Argentina. ECT treatment requires a minimum electric field and anti-cancer drugs (e.g., bleomycin). Irregularly shaped tumors may induce ECT treatment failure because of irregular electric field distribution. Conductive gels have been suggested as a means to increase the homogeneity of the electrical field distribution. The aim of this work was to evaluate if commercial conductive gels could increase the safety of ECT. A veterinary case study of ECT in a dog provided the tumor dimensions for the numerical model. Electrode displacement and commercial conductive gels were simulated to determine if they improved ECT treatments. We conclude that a commercial gel having a conductivity of 0.2 S/m when used in combination with effective treatment planning may improve the outcome of electrochemotherapy procedures.

Electroporation optimizes the uptake of boron-10 by tumor for boron neutron capture therapy (BNCT) mediated by GB-10: a boron biodistribution study in the hamster cheek pouch oral cancer model

Boron neutron capture therapy (BNCT) is a promising cancer binary therapy modality that utilizes the nuclear capture reaction of thermal neutrons by boron-10 resulting in a localized release of high- and low-linear energy transfer (LET) radiation. Electrochemotherapy (ECT) is based on electroporation (EP) that induces opening of pores in cell membranes, allowing the entry of compounds. Because EP is applied locally to a tumor, the compound is incorporated preferentially by tumor cells. Based on the knowledge that the therapeutic success of BNCT depends centrally on the boron content in tumor and normal tissues and that EP has proven to be an excellent facilitator of tumor biodistribution of an anti-tumor agent, the aim of this study was to evaluate if EP can optimize the delivery of boronated compounds. We performed biodistribution studies and qualitative microdistribution analyses of boron employing the boron compound sodium decahydrodecaborate (GB-10) + EP in the hamster cheek pouch oral cancer model. Syrian hamsters with chemically induced exophytic squamous cell carcinomas were used. A typical EP treatment was applied to each tumor, varying the moment of application with respect to the administration of GB-10 (early or late). The results of this study showed a significant increase in the absolute and relative tumor boron concentration and optimization of the qualitative microdistribution of boron by the use of early EP + GB-10 versus GB-10 without EP. This strategy could be a tool to improve the therapeutic efficacy of BNCT/GB-10 in vivo.

Electrochemotherapy in Veterinary Oncology: State-of-the-Art and Perspectives

Tumor microenvironment represents a key obstacle for the effectiveness of anticancer drugs. Electrochemotherapy involves the systemic or local delivery of lipophobic drugs such as bleomycin and cisplatin, with the application of permeabilizing electric pulses having appropriate amplitude and waveforms. This greatly enhances the uptake of these drugs by an estimated factor of 700-fold for bleomycin and 4 to 8 times for cisplatin. Because of its efficacy and limited morbidity, this therapeutic option is becoming more and more available in veterinary oncology either as an adjuvant to surgery or as first line of treatment with palliative or curative purposes.

A combination of electrochemotherapy, gene electrotransfer of plasmid encoding canine IL-12 and cytoreductive surgery in the treatment of canine oral malignant melanoma

The aim of this study was to evaluate the safety and efficacy of the combination of electrochemotherapy (ECT) with bleomycin and gene electrotransfer (GET) of plasmid encoding canine interleukin 12 (IL-12) for the treatment of canine oral malignant melanoma (OMM). Our focus was to determine the effect of the treatment on achieving local tumor control and stimulation of an antitumor immune response. Nine dogs with histologically confirmed OMM stage I to III were included in a prospective, non-randomized study. The dogs were treated with a combination of cytoreductive surgery, ECT and IL-12 GET, which was repeated up to five times, depending on the clinical response to the treatment, evaluated according to the follow-up protocol (7, 14 and 28 days after, the last treatment). One month after treatment, the objective response (OR) rate was 67% (6/9). Median survival time (MST) was 6 months and, even though the disease progressed in 8/9 patients at the end of the observation period (2 to 22 months), four animals were euthanized due to tumor-unrelated reasons. In addition, we observed a decline in the percentage of regulatory T cells (Treg) in the peripheral blood in the course of the treatment, which could be attributed to a systemic antitumor response to IL-12 GET. The results of this study suggest that a combination of ECT and IL-12 GET may be beneficial for dogs with OMM, especially when other treatment approaches are not acceptable due to their invasiveness or cost.