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

Immunogenic Effects and Clinical Applications of Electroporation-Based Treatments

Immunotherapy can now be regarded as an attractive approach for cancer and infectious disease treatments [...].

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.

Electrochemotherapy Plus IL-2+IL-12 Gene Electrotransfer in Spontaneous Inoperable Stage III-IV Canine Oral Malignant Melanoma

Electrochemotherapy (ECT) is a standard of care in veterinary and human oncology. The treatment induces a well-characterized local immune response which is not able to induce a systemic response. In this retrospective cohort study, we evaluated the addition of gene electrotransfer (GET) of canine IL-2 peritumorally and IL-12 intramuscularly to enhance the immune response. Thirty canine patients with inoperable oral malignant melanoma were included. Ten patients received ECT+GET as the treatment group, while twenty patients received ECT as the control group. Intravenous bleomycin for the ECT was used in both groups. All patients had compromised lymph nodes which were surgically removed. Plasma levels of interleukins, local response rate, overall survival, and progression-free survival were evaluated. The results show that IL-2 and IL-12 expression peaked around days 7-14 after transfection. Both groups showed similar local response rates and overall survival times. However, progression-free survival resulted significantly better in the ECT+GET group, which is a better indicator than overall survival, as it is not influenced by the criterion used for performing euthanasia. We can conclude that the combination of ECT+GET using IL-2 and IL-12 improves treatment outcomes by slowing down tumoral progression in stage III-IV inoperable canine oral malignant melanoma.

Potential dual synergy between electrochemotherapy and sequence of immunotherapies in metastatic melanoma: A case report

Immune checkpoint inhibitors have changed the natural history of advanced melanoma. Despite this, a notable proportion of patients immediately relapse or develop resistance during immunotherapy, especially with the appearance of superficial metastases and consequently with a dramatic impact on clinical outcomes. Local treatment by electrochemotherapy (ECT), parallel to regional control with palliative aim, seems to release neoantigens potentially determining a significant systemic anticancer immune reactivation. The present study reported a case of a patient with metastatic melanoma receiving Pembrolizumab, electrochemotherapy and then Ipilimumab for in-transit and finally locoregional lymph nodes and distant bone metastases with experience of clinic-radiological remission. Specifically, the present patient progressed during adjuvant treatment with in-transit metastases on the scalp; he underwent two cycle of ECT obtaining partial and then unexpected and very fast nearly complete response with the Ipilimumab treatment. Concomitantly, he developed grade 4 endocrine adverse events (hypophysitis and diabetes mellitus type I) as immune-related toxicities. At 12 months from ECT the patient is in ECOG Performance Status 0 and he has resumed a regular social life. In our experience, ECT in two administrations increased and accelerated the response of Ipilimumab. The present confirmed its promising contribution in inducing a powerful immune response in order to overcome primary or acquired resistance to immune checkpoint inhibitors such as anti-programmed death antigen-1 drugs.

Advances of Electroporation-Related Therapies and the Synergy with Immunotherapy in Cancer Treatment

Electroporation is the process of instantaneously increasing the permeability of a cell membrane under a pulsed electric field. Depending on the parameters of the electric pulses and the target cell electrophysiological characteristics, electroporation can be either reversible or irreversible. Reversible electroporation facilitates the delivery of functional genetic materials or drugs to target cells, inducing cell death by apoptosis, mitotic catastrophe, or pseudoapoptosis; irreversible electroporation is an ablative technology which directly ablates a large amount of tissue without causing harmful thermal effects; electrotherapy using an electric field can induce cell apoptosis without any aggressive invasion. Reversible and irreversible electroporation can also activate systemic antitumor immune response and enhance the efficacy of immunotherapy. In this review, we discuss recent progress related to electroporation, and summarize its latest applications. Further, we discuss the synergistic effects of electroporation-related therapies and immunotherapy. We also propose perspectives for further investigating electroporation and immunotherapy in cancer treatment.

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.

Cancer Vaccines and Immunotherapy for Tumor Prevention and Treatment

In this editorial, we highlight articles published in this Special Issue of Vaccines on “Cancer Vaccines and Immunotherapy for Tumor Prevention and Treatment”, recent developments in the field of cancer vaccines, and the potential for immunotherapeutic combinations in cancer care. This issue covers important developments and progress being made in the cancer vaccine field and possible future directions for exploring new technologies to produce optimal immune responses against cancer and expand the arena of prophylactic and therapeutic cancer vaccines for the treatment of this deadly disease.

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.

Results of Dynamic Contrast-Enhanced Ultrasound Correlate With Treatment Outcome in Canine Neoplasia Treated With Electrochemotherapy and Interleukin-12 Plasmid Electrotransfer

Electrochemotherapy (ECT) and/or gene electrotransfer of plasmid DNA encoding interleukin-12 (GET pIL-12) are effective treatments for canine cutaneous, subcutaneous, and maxillofacial tumors. Despite the clinical efficacy of the combined treatments of ECT and GET, data on parameters that might predict the outcome of the treatments are still lacking. This study aimed to investigate whether dynamic contrast-enhanced ultrasound (DCE-US) results of subcutaneous tumors differ between tumors with complete response (CR) and tumors without complete response (non-CR) in dogs treated with ECT and GET pIL-12. Eight dogs with a total of 12 tumor nodules treated with ECT and GET pIL-12 were included. DCE-US examinations were performed in all animals before and immediately after therapy as well as 8 h and 1, 3, and 7 days later. Clinical follow-up examinations were performed 7 and 14 days, 1 and 6 months, and 1 year after treatment. Numerous significant differences in DCE-US parameters were noted between tumors with CR and non-CR tumors; perfusion and perfusion heterogeneity were lower in CR tumors than in non-CR tumors. Therefore, studies with larger numbers of patients are needed to investigate whether DCE-US results can be used to predict treatment outcomes and to make effective decisions about the need for repeated therapy or different treatment combinations in individual patients.

Evaluation of a Novel Plasmid for Simultaneous Gene Electrotransfer-Mediated Silencing of CD105 and CD146 in Combination with Irradiation

Targeting tumor vasculature through specific endothelial cell markers represents a promising approach for cancer treatment. Here our aim was to construct an antibiotic resistance gene-free plasmid encoding shRNAs to simultaneously target two endothelial cell markers, CD105 and CD146, and to test its functionality and therapeutic potential in vitro when delivered by gene electrotransfer (GET) and combined with irradiation (IR). Functionality of the plasmid was evaluated by determining the silencing of the targeted genes using qRT-PCR. Antiproliferative and antiangiogenic effects were determined by the cytotoxicity assay tube formation assay and wound healing assay in murine endothelial cells 2H-11. The functionality of the plasmid construct was also evaluated in malignant melanoma tumor cell line B16F10. Additionally, potential activation of immune response was measured by induction of DNA sensor STING and proinflammatory cytokines by qRT-PCR in endothelial cells 2H-11. We demonstrated that the plasmid construction was successful and can efficiently silence the expression of the two targeted genes. As a consequence of silencing, reduced migration rate and angiogenic potential was confirmed in 2H-11 endothelial cells. Furthermore, induction of DNA sensor STING and proinflammatory cytokines were determined, which could add to the therapeutic effectiveness when used in vivo. To conclude, we successfully constructed a novel plasmid DNA with two shRNAs, which holds a great promise for further in vivo testing.