Intraoperative versus postoperative electrochemotherapy in high grade soft tissue sarcomas: a preliminary study in a spontaneous feline model

Treatment of metastatic apocrine sweat gland adenocarcinoma in a cat with association of surgical resection and angular oris reconstruction, extensive lymphadenectomy, electrochemotherapy and systemic chemotherapy

Apocrine sweat gland adenocarcinoma (ASGAC) is a rare skin carcinoma in cats. In some cases, this tumor occurs in anatomical sites of challenging wide surgical resection, which increases the need for adjuvant therapies for residual disease. These would include radiotherapy or electrochemotherapy (ECT), local treatments for invasive tumors in companion animals often associated with surgery. However, the current literature for ASGAC treatment is limited and there are no reports of ECT as an adjuvant therapy. In this case report, we account for the case of an 11-year-old cat with a history of a non-ulcerated recurrent ASGAC, measuring 1.3 × 1.0 cm, located by the rostral mandibular region. Surgical resection was performed and included the angularis oris axial flap for facial reconstruction associated with electroporation of the surgical bed and, post-operatively, in the surgical scar. Histopathological results confirm the presence of a recurrent ASGAC. Immunostaining revealed cyclooxygenase 2 (COX-2) expression with a score of 6, 50% positivity in Ki-67 and positive for pan-cytokeratin (PCK AE-1/ AE-3). A selective COX-2 inhibitor was initiated along with systemic chemotherapy with chlorambucil. The local approach including surgery and ECT was chosen due to the unfavorable anatomical site for extensive resection and the unavailability of radiotherapy. Subsequently, carboplatin chemotherapy was required due to metastasis in the mandibular lymph node. This case report supports the effectiveness of a multimodal treatment including surgery, ECT and chemotherapy in a cat with recurrent ASGAC.

Electrochemotherapy in dogs and cats-A review

Electrochemotherapy (ECT) is a treatment modality that combines the electroporation of cell membranes with chemotherapy to facilitate the transport of non-permeant molecules into cells. Several canine and feline studies have shown promising results, suggesting that ECT can be a valid adjuvant or alternative treatment option for some tumours. The objective of this paper is to provide a bibliographic review of the principles and applications of ECT in veterinary medicine and to compare to its use in human medicine.

Electroporation in Translational Medicine: From Veterinary Experience to Human Oncology

Electroporation (EP) is a broadly accepted procedure that, through the application of electric pulses with appropriate amplitudes and waveforms, promotes the delivery of anticancer molecules in various oncology therapies. EP considerably boosts the absorptivity of targeted cells to anticancer molecules of different natures, thus upgrading their effectiveness. Its use in veterinary oncology has been widely explored, and some applications, such as electrochemotherapy (ECT), are currently approved as first-line treatments for several neoplastic conditions. Other applications include irreversible electroporation and EP-based cancer vaccines. In human oncology, EP is still mostly restricted to therapies for cutaneous tumors and the palliation of cutaneous and visceral metastases of malignant tumors. Fields where veterinary experience could help smooth the clinical transition to humans include intraoperative EP, interventional medicine and cancer vaccines. This article recapitulates the state of the art of EP in veterinary and human oncology, recounting the most relevant results to date.

Electrochemotherapy for the treatment of basal cell tumours of the nasal planum in three cats

Case series summary

Malignant basal cell tumours may be seen on or near the nasal planum in cats, and include basal cell carcinomas, which are common, and basosquamous carcinomas, which are rare. Reported treatments for these tumours include surgical excision, radiotherapy, photodynamic therapy and cryosurgery. This report describes the successful management of basal cell tumours with electrochemotherapy (ECT), including calcium electroporation, in three cats.

Relevance and novel information

All patients had a complete response lasting at least 9 months to 1 year. The adverse effects of this treatment were minimal and were limited to nasal discharge, sneezing and scabs at the treatment site. ECT and calcium electroporation are a safe, minimally invasive and effective option for the treatment of feline basal cell carcinoma and basosquamous carcinomas.

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.

Comparison of two different doses of bleomycin in electrochemotherapy protocols for feline cutaneous squamous cell carcinoma nonsegregated from ultraviolet light exposure

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin tumors in cats due to chronic exposure to ultraviolet light. Local treatments such as electrochemotherapy (ECT) promote disease control or even complete remission. We hypothesize that cats could benefit from treatments using bleomycin at reduced dosages. A prospective nonrandomized single-blind study evaluated the clinical parameters, site lesion, staging, disease-free interval (DFI) and survival time by comparing the standard dose of bleomycin (15,000 UI/m2) (n = 22) with a reduced dose (10,000 UI/m2) (n = 34) in cats with cSCC that underwent ECT as the sole treatment modality. No statistically significant difference in DFI or overall survival was observed between the 2 groups. A higher DFI was found in cats with a small tumor size (less than 0.33 cm3) compared with that for cats with a large tumor size (P = 0.045). Furthermore, a reduced overall survival time for cats with a higher stage in the standard group SG (T3 and T4) (P = 0.004) was observed when compared to that for cats with a lower stage (T1 and T2). In conclusion, ECT using both doses of bleomycin may achieve the same response rate in terms of the overall response, DFI, and overall survival.

Combination of bleomycin and cisplatin as adjuvant electrochemotherapy protocol for the treatment of incompletely excised feline injection-site sarcomas: A retrospective study

Background

fFeline injection-site sarcomas (FISSs) are mesenchymal tumors that can occur in cats after injections of different medical agents and are easily prone to recurrence.

Aim

The aims of this study were to report treatment outcomes for cats with feline injection-site sarcomas (FISSs) treated with both bleomycin and cisplatin, per adjuvant electrochemotherapy (ECT) protocol.

Methods

The medical records of cats with a diagnosis of FISS that were treated with ECT using both bleomycin and cisplatin were retrospectively evaluated. A total of 27 cats were available for statistical evaluation of their response. The cats received intravenous 20 mg/m2 bleomycin, and the tumor bed and margins were infiltrated with cisplatin at the dose of 0.5 mg/cm2. Then, the trains of permeabilizing biphasic electric pulses lasting 50 + 50 µseconds each were delivered in bursts of 1,300 V/cm using caliper electrodes under sedation. A second session was performed 2 weeks later.

Results

Side effects were limited to local inflammation in three cats. Three cats developed local tumor recurrence at days 180, 180, and 545 after surgery, two cats developed recurrence and metastases at 100 and 505 days after surgery, and two cats experienced distant metastases. A median time to recurrence could not be calculated as over 80% of the study population remained disease free or were censored due to death from other causes. Mean survival time was 985 days, and median cumulative survival for all cases was 1,000 days.

Conclusion

When compared to historical controls, the results of this study demonstrate the superior rates of tumor-free survival and disease-free interval. This adjuvant therapy could be a useful addition to the current options for FISS in consideration of its efficacy, limited toxicity, and ease of administration.

Treatment of feline injection-site sarcoma with surgery and iridium-192 brachytherapy: retrospective evaluation of 22 cats

OBJECTIVES

The aim of this retrospective descriptive study was to determine the effectiveness of using iridium implants in addition to surgery in cats with feline injection-site sarcomas (FISSs) in terms of time to progression and disease-specific survival and to identify prognostic factors for patient outcome.

METHODS

Medical records of cats presented at our institution with FISS were reviewed. Inclusion criteria included histologic diagnosis of a tumor type associated with post-injection neoplastic development, tumor located at a site associated with vaccination, no other therapies prior to the administration of brachytherapy with the exception of surgery and adequate follow-up data.

RESULTS

Twenty-two cats with FISS were treated with surgery and brachytherapy delivered by postoperative iridium-192 interstitial implants. Radiation doses ranged from 4000 to 6000 cGy (median dose 5079.55 cGy), with most doses delivered over 7 days. The median number of surgeries prior to brachytherapy was one (range 1-4). The complications associated with postoperative brachytherapy were typically mild, although four cats developed more severe complications. The median time to progression for all cats was 619 days and disease-specific survival time for all cats was 1242 days. The 1 and 2 year tumor-free rates in these cats were 63.6% and 40.9%, respectively. The local failure rate was 54.5% and the distant failure rate was 13.6% due to lung metastasis. There was a significant difference in time to progression of cats that had a single surgery performed prior to brachytherapy and those that had multiple surgeries (undefined vs 310 days; P = 0.01). There were no other statistically significant identified prognostic factors.

CONCLUSIONS AND RELEVANCE

These data suggest that the addition of brachytherapy postoperatively in cats with FISS was well tolerated and is comparable to other forms of adjuvant therapy.

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.

Soft tissue sarcoma in dogs: A treatment review and a novel approach using electrochemotherapy in a case series

Canine soft tissue sarcomas (STSs) are locally invasive mesenchymal neoplasms. Electrochemotherapy (ECT) is an antitumour local ablative treatment that uses electric pulses to enhance the intracellular delivery of cytotoxic drugs. The aim of this retrospective study was to review the current treatment for STSs and to evaluate the efficacy and safety of ECT with bleomycin in canine STSs. Fifty-two dogs with 54 STSs were included. Three groups were arranged: (a) ECT alone, (b) intra-operative ECT and (c) adjuvant ECT. Signalment, tumour size, location, histological grade and margins and ECT parameters were collected. Recurrence rate (RR) and disease-free interval (DFI) were calculated. Treatment toxicity was assessed using a 6-point scale. STSs were mostly located on limbs (77.8%). Median tumour size was 4.3 cm (range 0.4-17.0 cm). Most STSs were grade I (47.7%) and II (50.0%), and histological margins were incomplete in 94.5% of cases. Two complete remissions, one partial remission and one stable disease were recorded in group 1. Group 2 and 3 were similar for tumour location, size and grade, histological margins, treatment toxicity, pulse frequency and voltage. Moreover, RR and DFI were similar between group 2 and 3 (23% and 25%, 81.5 and 243 days, respectively). Local toxicity post ECT was mild (score ≤ 2) in 66.7% of cases. Higher toxicity score was associated with higher pulse voltage (1200 vs 1000 V/cm) (P = 0.0473). ECT coupled with bleomycin resulted safe and efficient in tumour local control and should be considered as an option for treatment of canine STSs.

Adjuvant electrochemotherapy with bleomycin and cisplatin combination for canine soft tissue sarcomas: A study of 30 cases

Electrochemotherapy (ECT) couples the administration of anticancer drugs with the delivery of electric pulses that increase the drug uptake through the cell membranes, thus resulting in an improved efficacy. This study has evaluated the tolerability and efficacy of the combination of systemic bleomycin and local cisplatin as ECT agents for incompletely excised canine soft tissue sarcoma (STS). Thirty dogs with incompletely excised STSs were enrolled. The dogs received intravenous 20 mg/m² bleomycin, and the tumor bed and margins were infiltrated with cisplatin at the dose of 0.5 mg/cm². Then, trains of permeabilizing biphasic electric pulses were applied under sedation. More precisely, 5 min after the injection of the chemotherapy agents, sequences of eight biphasic pulses lasting 50 + 50 μsec each, were delivered in bursts of 1,300 V/cm using caliper electrodes. A second session was performed 2 wk later. The treatment was well tolerated and side effects were minimal. Twenty-six dogs had no evidence of recurrence at the time of manuscript writing; four had recurrence and one of the four recurring dogs died of lung metastases. Median estimated disease free was 857 d. Perivascular wall tumors response was compared to that of the other STSs, but the difference in outcome was not significant. ECT using combination of bleomycin and cisplatin appears to be effective in the treatment of incompletely resected STSs in dogs. This therapeutic approach could be a useful addition to the current options in consideration of its low cost, limited toxicity, and ease of administration.

Electrochemotherapy palliation of an oral squamous cell carcinoma in an African hedgehog (Atelerix albiventris)

A five-year-old female African hedgehog (Atelerix albiventris) was referred for a one month growing oral mass. The hedgehog was quiet, alert and responsive, with a 1.00 × 1.50 cm ulcerated lesion on the mandible. The patient was staged with total body radiographs, hematological and biochemical analyses and the mass was biopsied under anesthesia. The excised tissue was reported to be a squamous cell carcinoma. At this time, due to the extension of the mass, a surgical excision was not a therapeutic option and the tumor was palliated with electrochemotherapy (ECT). Monthly sessions of ECT were performed using intra-lesional bleomycin injection followed by trains of biphasic electric pulses. The treatment was well tolerated and the patient remained in partial remission for five months until tumor progression. At that time the pet was euthanized. The ECT resulted in improved local control and should be considered as a possible adjuvant treatment in exotic pets with advanced tumors.

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.

Electroporation in veterinary oncology

Cancer treatments in veterinary medicine continue to evolve beyond the established standard therapies of surgery, chemotherapy and radiation therapy. New technologies in cancer therapy include a targeted mechanism to open the cell membrane based on electroporation, driving therapeutic agents, such as chemotherapy (electro-chemotherapy), for local control of cancer, or delivery of gene-based products (electro-gene therapy), directly into the cancer cell to achieve systemic control. This review examines electrochemotherapy and electro-gene therapy in veterinary medicine and considers future directions and applications.

Electroporation Enhances Bleomycin Efficacy in Cats with Periocular Carcinoma and Advanced Squamous Cell Carcinoma of the Head

Background

Advanced carcinoma of the head represents a substantial health problem in cats for local control and overall survival.

Objectives

Evaluate the capability of electrochemotherapy (ECT) to improve bleomycin efficacy in cats with periocular carcinoma and advanced carcinoma of the head.

Animals

Twenty‐one cats with periocular carcinoma (17 squamous cell carcinoma [SCC] and 4 anaplastic carcinoma) and 26 cats with advanced SCC of the head.

Methods

Nonrandomized prospective controlled study. Periocular carcinoma cohorts: 12 cats were treated with bleomycin (15 mg/m²IV) coupled with ECT under anesthesia; 9 cats were treated with bleomycin alone. Advanced head SCC cohorts: 14 cats were treated with bleomycin (15 mg/m²IV) coupled with ECT administered under sedation; 12 control cats were treated with bleomycin alone. ECT treatments (2–8) were performed every other week until complete remission (CR) or tumor progression occurred.

Results

Toxicities were minimal and mostly treated symptomatically. Overall response rate in the ECT treated animals was 89% (21 Complete Response [CR] and 2 Partial Response [PR]) whereas controls had response rate of 33% (4 CR and 3 PR). Median time to progression in ECT group was 30.5 months, whereas in controls it was 3.9 months (P < .0001). Median time to progression for ECT cohorts was 24.2 months for periocular cohort and 20.6 in advanced head SCC cohort, respectively.

Conclusions

Electrochemotherapy is well tolerated for advanced SCC of the head in cats; its use may be considered among loco‐regional strategies for cancer therapy in sensitive body regions such as periocular region.

Electrochemotherapy in veterinary oncology: from rescue to first line therapy

Electroporation is a delivery technique that is gaining popularity among the veterinary community due to its low cost, ease of application, and flexibility. It combines the administration of pharmaceutical compounds such as chemotherapy agents, antisense, and plasmids to the application of permeabilizing pulses. This chapter reviews the veterinary results obtained through the delivery of anticancer drugs (electrochemotherapy) and genes (electro-gene therapy).

Near-infrared optical guided surgery of highly infiltrative fibrosarcomas in cats using an anti-αvß3 integrin molecular probe

We investigated how near-infrared imaging could improve highly infiltrative spontaneous fibrosarcoma surgery in 12 cats in a clinical veterinary phase. We used an RGD-based nanoprobe at different doses and times before surgery and a portable clinical grade imaging system. All tumours were labelled by the tracer and had an overall tumour-to-healthy tissue ratio of 14±1 during surgery. No false negatives were found, and the percentage of tumour cells was linearly correlated with the fluorescence intensity. All cats recovered well and were submitted to long-term follow-up that is currently on-going 1year after the beginning of the study.

Pardaxin, a fish antimicrobial peptide, exhibits antitumor activity toward murine fibrosarcoma in vitro and in vivo

The antitumor activity of pardaxin, a fish antimicrobial peptide, has not been previously examined in in vitro and in vivo systems for treating murine fibrosarcoma. In this study, the antitumor activity of synthetic pardaxin was tested using murine MN-11 tumor cells as the study model. We show that pardaxin inhibits the proliferation of MN-11 cells and reduces colony formation in a soft agar assay. Transmission electron microscopy (TEM) showed that pardaxin altered the membrane structure similar to what a lytic peptide does, and also produced apoptotic features, such as hollow mitochondria, nuclear condensation, and disrupted cell membranes. A qRT-PCR and ELISA showed that pardaxin induced apoptosis, activated caspase-7 and interleukin (IL)-7r, and downregulated caspase-9, ATF 3, SOCS3, STAT3, cathelicidin, p65, and interferon (IFN)-γ suggesting that pardaxin induces apoptosis through the death receptor/nuclear factor (NF)-κB signaling pathway after 14 days of treatment in tumor-bearing mice. An antitumor effect was observed when pardaxin (25 mg/kg; 0.5 mg/day) was used to treat mice for 14 days, which caused significant inhibition of MN-11 cell growth in mice. Overall, these results indicate that pardaxin has the potential to be a novel therapeutic agent to treat fibrosarcomas.

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.

Electroporation increases antitumoral efficacy of the bcl-2 antisense G3139 and chemotherapy in a human melanoma xenograft

BACKGROUND

Nucleic acids designed to modulate the expression of target proteins remain a promising therapeutic strategy in several diseases, including cancer. However, clinical success is limited by the lack of efficient intracellular delivery. In this study we evaluated whether electroporation could increase the delivery of antisense oligodeoxynucleotides against bcl-2 (G3139) as well as the efficacy of combination chemotherapy in human melanoma xenografts.

METHODS

Melanoma-bearing nude mice were treated i.v. with G3139 and/or cisplatin (DDP) followed by the application of trains of electric pulses to tumors. Western blot, immunohistochemistry and real-time PCR were performed to analyze protein and mRNA expression. The effect of electroporation on muscles was determined by histology, while tumor apoptosis and the proliferation index were analyzed by immunohistochemistry. Antisense oligodeoxynucleotides tumor accumulation was measured by FACS and confocal microscopy.

RESULTS

The G3139/Electroporation combined therapy produced a significant inhibition of tumor growth (TWI, more than 50%) accompanied by a marked tumor re-growth delay (TRD, about 20 days). The efficacy of this treatment was due to the higher G3139 uptake in tumor cells which led to a marked down-regulation of bcl-2 protein expression. Moreover, the G3139/EP combination treatment resulted in an enhanced apoptotic index and a decreased proliferation rate of tumors. Finally, an increased tumor response was observed after treatment with the triple combination G3139/DDP/EP, showing a TWI of about 75% and TRD of 30 days.

CONCLUSIONS

These results demonstrate that electroporation is an effective strategy to improve the delivery of antisense oligodeoxynucleotides within tumor cells in vivo and it may be instrumental in optimizing the response of melanoma to chemotherapy. The high response rate observed in this study suggest to apply this strategy for the treatment of melanoma patients.

Antivascular effects of electrochemotherapy: implications in treatment of bleeding metastases

Solid tumors of various etiologies can be treated efficiently by electrochemotherapy (ECT), a combined use of electroporation (EP) and chemotherapeutic drugs, such as bleomycin and cisplatin. EP alone and ECT in particular, induce a profound reduction in tumor blood flow, which contributes to the antitumor effect. After EP and ECT, the time course of blood flow changes and follows the same two-phase pattern. The first rapid and short-lived vasoconstriction phase is followed by the second much longer-lived phase resulting from disrupted cytoskeletal structures and a compromised barrier function of the microvascular endothelium. In the case of ECT, however, tumor vascular endothelial cells are also affected by the chemotherapeutic drug, which leads to irrecoverable damage to tumor vessels and to a further decrease in tumor blood flow within hours after application of ECT. Tumor cells surviving the direct effects of ECT are consequently exposed to lack of oxygen and nutrients and are pushed into the secondary cascade of induced cell death. Clinically, the antitumor effectiveness of ECT has been proven extensively in the treatment of melanoma metastases, with 70-80% complete responses. The antivascular effects of ECT were also exploited for palliative treatment of bleeding melanoma metastases, with immediate cessation of bleeding and very good antitumor effectiveness. The antivascular effect of ECT is of utmost importance for translation of ECT into the treatment of deep-seated tumors, especially in well vascularized organs, such as the liver, where it prevents bleeding of the treated area.

Electrodelivery of drugs into cancer cells in the presence of poloxamer 188

In the present study it is shown that poloxamer 188, added before or immediately after an electrical pulse used for electroporation, decreases the number of dead cells and at the same time does not reduce the number of reversible electropores through which small molecules (cisplatin, bleomycin, or propidium iodide) can pass/diffuse. It was suggested that hydrophobic sections of poloxamer 188 molecules are incorporated into the edges of pores and that their hydrophilic parts act as brushy pore structures. The formation of brushy pores may reduce the expansion of pores and delay the irreversible electropermeability. Tumors were implanted subcutaneously in both flanks of nude mice using HeLa cells, transfected with genes for red fluorescent protein and luciferase. The volume of tumors stopped to grow after electrochemotherapy and the use of poloxamer 188 reduced the edema near the electrode and around the subcutaneously growing tumors.

Electrodelivery of drugs into cancer cells in the presence of poloxamer 188

In the present study it is shown that poloxamer 188, added before or immediately after an electrical pulse used for electroporation, decreases the number of dead cells and at the same time does not reduce the number of reversible electropores through which small molecules (cisplatin, bleomycin, or propidium iodide) can pass/diffuse. It was suggested that hydrophobic sections of poloxamer 188 molecules are incorporated into the edges of pores and that their hydrophilic parts act as brushy pore structures. The formation of brushy pores may reduce the expansion of pores and delay the irreversible electropermeability. Tumors were implanted subcutaneously in both flanks of nude mice using HeLa cells, transfected with genes for red fluorescent protein and luciferase. The volume of tumors stopped to grow after electrochemotherapy and the use of poloxamer 188 reduced the edema near the electrode and around the subcutaneously growing tumors.

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

The treatment of soft tissue tumors needs the coordinated adoption of surgery with radiation therapy and eventually, chemotherapy. The radiation therapy (delivered with a linear accelerator) can be preoperative, intraoperative, or postoperative. In selected patients adjuvant brachytherapy can be adopted. The goal of these associations is to achieve tumor control while maximally preserving the normal tissues from side effects. Unfortunately, the occurrence of local and distant complications is still elevated. Electrochemotherapy is a novel technique that combines the administration of anticancer agents to the application of permeabilizing pulses in order to increase the uptake of antitumor molecules. While its use in humans is still confined to the treatment of cutaneous neoplasms or the palliation of skin tumor metastases, in veterinary oncology this approach is rapidly becoming a primary treatment. This review summarizes the recent progresses in preclinical oncology and their possible transfer to humans.

Electrochemotherapy for the treatment of squamous cell carcinoma in cats: A preliminary report

Squamous cell carcinomas (SCC) of the skin are commonly described in cats. Reported treatments include surgery, radiation therapy and photodynamic therapy. This preliminary study reports on the management of these lesions combining the local administration of bleomycin (plus hyaluronidase for a more uniform distribution) with permeabilizing biphasic electric pulses. Nine cats with SCC graded T(2)-T(4) were treated over a 5 year period, and each cat received two sessions of electrochemotherapy (ECT) 1 week apart. The side effects of this treatment were minimal and limited to mild erythema of the nose. Seven of the cats (77.7%) had a complete response lasting up to 3 years. ECT seems to be a safe and effective option for the treatment of feline sun-induced squamous cell carcinomas and warrants further investigation.

Biphasic pulses enhance bleomycin efficacy in a spontaneous canine genital tumor model of chemoresistance: Sticker sarcoma

Sticker's sarcoma (also known as transmissible venereal tumor) is a horizontally transmitted neoplasm of the dog, that is passed with coitus. It is a locally aggressive tumor with a low tendency to metastatic spread. The most common locations are the genitals, the nose, the perianal area. Standard treatment consists with chemotherapy with vincristine, however other therapies such as, cryotherapy, immunotherapy or, in selected cases, radiation therapy, have been reported. In this article we describe the outcome of a small cohort of canine patients, with chemotherapy resistant transmissible venereal tumor (TVT), treated with bleomycin selectively driven by trains of biphasic pulses (electrochemotherapy). Three canine patients, with refractory TVT, entered the study and received two sessions of ECT under sedation. The pets had local injection of bleomycin at the concentration of 1.5 mg/ml and five minutes after the chemotherapy, trains of 8 biphasic electric pulses lasting 50 + 50 μs each, with 1 ms interpulse intervals, were delivered by means of modified caliper or, for difficult districts, through paired needle electrode. All the patients responded to the treatment and are still in remission at different times. Electrochemotherapy appears as a safe and efficacious modality for the treatment of TVT and warrants further investigations.

Electrochemotherapy in veterinary oncology

Electropermeabilization is a method that uses electric field pulses to induce an electrically mediated reorganization of the plasma membrane of cells. Electrochemotherapy combines local or systemic administration of chemotherapeutic drugs such as bleomycin or cisplatin that have poor membrane permeability with electropermeabilization by direct application of electric pulses to the tumors. Preclinical studies have demonstrated excellent antitumor effectiveness of electrochemotherapy on different animal models and various tumor types, minimal toxicity, and safety of the procedure. Based on results of preclinical studies, clinical studies were conducted in human patients, which demonstrated pronounced antitumor effectiveness of electrochemotherapy with 80-85% objective responses of the treated cutaneous and SC tumors. Clinical studies in veterinary oncology have demonstrated that electrochemotherapy is very effective in the treatment of cutaneous and SC tumors of different histologic types in cats, dogs, and horses. The results of these studies have also demonstrated approximately 80% long-lasting objective responses of tumors treated by electrochemotherapy. Primary tumors of different histologic types were treated. Electrochemotherapy in veterinary oncology has future promise to be highly effective, and could be used to treat primary or recurrent solitary or multiple cutaneous and SC tumors of different histology or as an adjuvant treatment to surgery.

Patterns of tumor response in canine and feline cancer patients treated with electrochemotherapy: preclinical data for the standardization of this treatment in pets and humans

Electrochemotherapy (ECT) is a novel anticancer therapy that is currently being evaluated in human and pet cancer patients. ECT associates the administration of an anti-tumor agent to the delivery of trains of appropriate waveforms. The increased uptake of chemotherapy leads to apoptotic death of the neoplasm thus resulting in prolonged local control and extended survival. In this paper we describe the histological features of a broad array of spontaneous tumors of companion animals receiving pulse-mediated chemotherapy. Multivariate statistical analysis of the percentage of necrosis and apoptosis in the tumors before and after ECT treatment, shows that only a high percentage of necrosis and apoptosis after the ECT treatment were significantly correlated with longer survivals of the patients (p < 0.0001 and p = 0.004, respectively). Further studies on this topic are warranted in companion animals with spontaneous tumors to identify new molecular targets for electrochemotherapy and to the develop new therapeutical protocols to be translated to humans.

Ganglioneuroblastoma in a cat: a rare neoplasm treated with electrochemotherapy

An 8-year-old male castrated cat was referred for sudden onset of lameness. Physical examination revealed a 1x2x1cm mass originating from a footpad of the right hind leg. A diagnosis of ganglioneuroblastoma was suggested by the tumour appearance following histopathological staining with haematoxylin and eosin and haematoxylin/van Gieson. Immunohistochemical staining for glial fibrillary acidic protein (GFAP), vimentin, neuron-specific enolase (NSE), neurofilament and S100 further confirmed the diagnosis. The staging process did not indicate metastatic spread. The cat was treated with three sessions of electrochemotherapy (ECT) 1 week apart, following local injection of bleomycin. The tumour had completely regressed within 1 week of the third ECT application and remained in remission for 402 days at which time a small recurrence was noted. The animal was given a further session of ECT using intra-lesional cisplatin and again went into remission. It remained tumour free at 450 days. Electrochemotherapy is considered a safe and effective treatment for localised neoplasms of cats and dogs and warrants further investigation.