Adjuvant electrochemotherapy in veterinary patients: a model for the planning of future therapies in humans

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.

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

Background

Nasal cavity tumors are usually diagnosed late, when they already have infiltrated adjacent tissues thus requiring very aggressive treatments with serious side effects. Here we use electrochemotherapy (ECT), a well demonstrated treatment modality for superficial tumors.

Materials and methods

In the case of deep-seated tumors, the main limitation of ECT is reaching the tumor with an appropriate electric field. To overcome this limitation we introduce the single needle electrode (SiNE), a minimally invasive device that can deliver an appropriate electric field with a simple procedure. Twenty-one canine patients with spontaneous tumors were selected, eleven were treated using the SiNE with ECT, and ten with surgery plus adjuvant chemotherapy as a control group.

Results

In the SiNE group, 27% achieved a complete response, 64% had a partial response, and 9% had a stable disease. This means that 91% of objective responses were obtained. The mean overall survival was 16.86 months (4–32 months, median 16.5 months), with a survival rate significantly higher (p = 0.0008) when compared with control group. The only side effect observed was the inflammation of the treated nasal passage, which was controlled with corticosteroid therapy for one week. One year after the treatment, 60% of the canine of the SiNE group vs. 10% of the control group remained alive, and after the 32 months follow-up, the survival rate were 30% and 0%, respectively.

Conclusions

ECT with the SiNE can be safely used in canine to treat nasal tumors with encouraging results.

Novel application for electrochemotherapy: Immersion of nasal cavity in dog

Electrochemotherapy is a new modality of local cancer treatment that increases the delivery of chemotherapy drugs into tumor cells by applying intense electric fields. This novel electrochemotherapy application was applied as an adjuvant to surgery and eliminated intranasal tumors in dog. The treatment challenges are the surgery limitations due to anatomy and residual tumor in the bone cavity. Most of the tumoral mass on nasal cavity was surgically removed. The internal nasal cavity was immersed in liquid and bleomycin before applying electric field. The solution was necessary to increase the superficial contact between plate electrodes and residual tumor. The numerical study demonstrated electrochemotherapy efficiency in different clinical situations. The proximity between electrodes and bone (<3 mm) and bone irregularities affect the electric field distribution on tumoral tissue. The tumoral tissue around bone protuberances tends to be eliminated. Electrochemotherapy with plate electrodes inside the cavity might not be effective. Different values of electric conductivity solution were studied; the ideal value was 0.5 S/m. The numerical and experimental results confirm the successful application of electrochemotherapy on dog nasal cavity.

Novel Instruments for the Implementation of Electrochemotherapy Protocols: From Bench Side to Veterinary Clinic

Electrochemotherapy (ECT) is a medical strategy that allows an increased efficacy of chemotherapy agents after the application of permeabilizing electric pulses having appropriate characteristics (form, voltage, frequency). In the past 10 years, the clinical efficacy of this therapeutic approach in several spontaneous models of tumors in animals has been shown. Moreover, some of the molecular and cellular mechanisms responsible for this phenomenon have been elucidated. Our group has been deeply involved in the development of new ECT protocols for companion animals, implementing the use of the technique as first line treatment, and evaluating different chemotherapy agents in laboratory animals as well as pets. This article summarizes the most important advances in veterinary ECT, including the development of novel equipment, therapeutic protocols, and their translation to humans. J. Cell. Physiol. 232: 490-495, 2017. © 2016 Wiley Periodicals, Inc.

Electrochemotherapy by pulsed electromagnetic field treatment (PEMF) in mouse melanoma B16F10 in vivo

Introduction

Pulsed electromagnetic field (PEMF) induces pulsed electric field, which presumably increases membrane permeabilization of the exposed cells, similar to the conventional electroporation. Thus, contactless PEMF could represent a promising approach for drug delivery.

Materials and methods

Noninvasive electroporation was performed by magnetic field pulse generator connected to an applicator consisting of round coil. Subcutaneous mouse B16F10 melanoma tumors were treated with intravenously injection of cisplatin (CDDP) (4 mg/kg), PEMF (480 bipolar pulses, at frequency of 80 Hz, pulse duration of 340 μs) or with the combination of both therapies (electrochemotherapy − PEMF + CDDP). Antitumor effectiveness of treatments was evaluated by tumor growth delay assay. In addition, the platinum (Pt) uptake in tumors and serum, as well as Pt bound to the DNA in the cells and Pt in the extracellular fraction were measured by inductively coupled plasma mass spectrometry.

Results

The antitumor effectiveness of electrochemotherapy with CDDP mediated by PEMF was comparable to the conventional electrochemotherapy with CDDP, with the induction of 2.3 days and 3.0 days tumor growth delay, respectively. The exposure of tumors to PEMF only, had no effect on tumor growth, as well as the injection of CDDP only. The antitumor effect in combined treatment was related to increased drug uptake into the electroporated tumor cells, demonstrated by increased amount of Pt bound to the DNA. Approximately 2-fold increase in cellular uptake of Pt was measured.

Conclusions

The obtained results in mouse melanoma model in vivo demonstrate the possible use of PEMF induced electroporation for biomedical applications, such as electrochemotherapy. The main advantages of electroporation mediated by PEMF are contactless and painless application, as well as effective electroporation compared to conventional electroporation.

Mechanisms of transfer of bioactive molecules through the cell membrane by electroporation

A short review of biophysical mechanisms for electrotransfer of bioactive molecules through the cell membrane by using electroporation is presented. The concept of transient hydrophilic aqueous pores and membrane electroporation mechanisms of single cells and cells in suspension models are analyzed. Alongside the theoretical approach, some peculiarities of drug and gene electrotransfer into cells and applications in clinical trials are discussed.

HF ultrasound vs PET-CT and telethermography in the diagnosis of In-transit metastases from melanoma: a prospective study and review of the literature

BACKGROUND

Over the past several years the incidence of cutaneous melanoma has rapidly increased. This tumor develops often in-transit metastases that significantly reduce patient survival at 5 years. To improve prognosis and quality of life in patients with melanoma metastases, a mini invasive procedure like electrochemotherapy (ECT) is adopted to remove superficial tissue lesions. To detect the melanoma metastases, high frequency (HF) ultrasound (US) is used. This technique, though, can be time-consuming and it needs an expert operator and a high performing machine. Therefore, we asked whether the US could be replaced or integrated with other less time-consuming techniques such as 18-FDG positron emission tomography/computed tomography (PET-CT) and telethermography (TT).

METHODS

Fifteen patients (4 males and 11 females - age range: 63-91) affected whit advanced stage melanoma were enrolled. They presented 52 in-transit metastases as detected by the three techniques used, HF-US, PET/CT and TT within 30 days before ECT.

RESULTS

All the 52 lesions were detected by HF-US (100%), 24/52 were detected by PET-CT (42,6%) and 15/52 were detected by TT (27,7%). PET-CT reported 3.7% false positives, while no false positive were reported by TT.

CONCLUSIONS

As US detected 100% lesions, compared to the other two techniques used, US, along with clinical examination, has still to be considered as gold standard in the diagnosis of metastatic lesions. US, associated with an exhaustive anamnesis and accurate clinical examination, cannot be replaced by either PET-CT or TT. When US performing devices and experienced operators are not available, though, it is highly recommended to integrate US with at least one of the other techniques. Under certain circumstances, as in the case of obese and non-collaborating patients or in patients with lymphatic stasis, these techniques should be integrated to obtain exact in-transit metastases evaluation.

Definition of novel electrochemotherapy parameters and validation of their in vitro and in vivo effectiveness

Electrochemotherapy (ECT) is a cancer therapy that conjugates the administration of a chemotherapy agent to the delivery of permeabilizing pulses released singularly or as bursts. This approach results in higher number of anticancer molecules delivered to their biological targets, but is also associated to undesirable side effects such as pain and muscular contractions. A new electroporator delivering train of eight biphasic pulses at the voltage of 1,300 V/cm lasting 50 + 50 µsec each, with a frequency of 1 Hz, and with 10-µsec interpulse intervals (total treatment time: 870 µsec/cm(2) of treated area) was tested in vitro on the human lung cancer cell line A549 and in vivo, both in mice xenografts and privately owned rabbits with spontaneous tumors. The tumor cell line was treated with electroporation using the new parameters, that showed improved drug efficacy in causing cell death. Mice with chemoresistant xenografts were treated as well with either the new parameters and with a previous protocol, confirming the higher tolerability and efficacy of the novel parameters. Finally, a cohort of six pet rabbits with advanced skin neoplasms were enrolled in a compassionate trial using the new parameters in adjuvant fashion. In terms of efficacy, none of the rabbits experienced tumor recurrence, showing minimal discomfort during the ECT sessions. The data described, demonstrate that the new permeabilizing protocol adopting biphasic electric pulses displays a significant higher efficacy compared to previous ECT treatments and substantial reduction of the associated morbidity.

Preclinical models in electrochemotherapy: the role of veterinary patients

Electrochemotherapy is a tumor treatment that adapts the systemic or local delivery of anticancer drugs by the application of permeabilizing electric pulses with appropriate amplitude and waveforms. This allows the use of lipophobic drugs, which frequently have a narrow therapeutic index, with a decreased morbidity for the patient, while maintaining appropriate anticancer efficacy. Electrochemotherapy is used in humans for the treatment of cutaneous neoplasms or the palliation of skin tumor metastases, and a standard operating procedure has been devised. In veterinary oncology, the electrochemotherapy approach is gaining popularity, becoming a first-line treatment in consideration of its high efficacy and low toxicity. This review summarizes the state of the art in veterinary oncology as a preclinical model.

Electrochemotherapy with cisplatin enhances local control after surgical ablation of fibrosarcoma in cats: an approach to improve the therapeutic index of highly toxic chemotherapy drugs

Background

Cancer is one of the most difficult current health challenges, being responsible for millions of deaths yearly. Systemic chemotherapy is the most common therapeutic approach, and the prevailing orientation calls for the administration of the maximum tolerated dose; however, considerable limitations exist including toxicities to healthy tissues and low achievable drug concentrations at tumor sites. Electrochemotherapy (ECT) is a tumor treatment that combines the systemic or local delivery of anticancer drugs with the application of permeabilizing electric pulses. In this article we evaluate the capability of ECT to allow the use of cisplatin despite its high toxicity in a spontaneous feline model of soft tissue sarcoma.

Methods

A cohort of sixty-four cats with incompletely excised sarcomas were treated with cisplatin-based adjuvant ECT and monitored for side effects. Their response was compared to that of fourteen cats treated with surgery alone.

Results

The toxicities were minimal and mostly treated symptomatically. ECT resulted in increased local control (median not reached at the time of writing) with a mean time to recurrence of 666 days versus 180 of controls.

Conclusions

We conclude that ECT is a safe and efficacious therapy for solid tumors; its use may be considered as part of strategies for the reintroduction of drugs with a narrow therapeutic index in the clinical protocols.