The Effects of Bipolar Cancellation Phenomenon on Nano-Electrochemotherapy of Melanoma Tumors: In Vitro and In Vivo Pilot.

The phenomenon known as bipolar cancellation is observed when biphasic nanosecond electric field pulses are used, which results in reduced electroporation efficiency when compared to unipolar pulses of the same parameters. Basically, the negative phase of the bipolar pulse diminishes the effect of the positive phase. Our study aimed to investigate how bipolar cancellation affects Ca2+ electrochemotherapy and cellular response under varying electric field intensities and pulse durations (3-7 kV/cm, 100, 300, and 500 ns bipolar 1 MHz repetition frequency pulse bursts, n = 100). As a reference, standard microsecond range parametric protocols were used (100 µs × 8 pulses). We have shown that the cancellation effect is extremely strong when the pulses are closely spaced (1 MHz frequency), which results in a lack of cell membrane permeabilization and consequent failure of electrochemotherapy in vitro. To validate the observations, we have performed a pilot in vivo study where we compared the efficacy of monophasic (5 kV/cm × ↑500 ns × 100) and biphasic sequences (5 kV/cm × ↑500 ns + ↓500 ns × 100) delivered at 1 MHz frequency in the context of Ca2+ electrochemotherapy (B16-F10 cell line, C57BL/6 mice, n = 24). Mice treated with bipolar pulses did not exhibit prolonged survival when compared to the untreated control (tumor-bearing mice); therefore, the bipolar cancellation phenomenon was also occurrent in vivo, significantly impairing electrochemotherapy. At the same time, the efficacy of monophasic nanosecond pulses was comparable to 1.4 kV/cm × 100 µs × 8 pulses sequence, resulting in tumor reduction following the treatment and prolonged survival of the animals.

Threshold Interphase Delay for Bipolar Pulses to Prevent Cancellation Phenomenon during Electrochemotherapy.

Electroporation-based procedures employing nanosecond bipolar pulses are commonly linked to an undesirable phenomenon known as the cancelation effect. The cancellation effect arises when the second pulse partially or completely neutralizes the effects of the first pulse, simultaneously diminishing cells' plasma membrane permeabilization and the overall efficiency of the procedure. Introducing a temporal gap between the positive and negative phases of the bipolar pulses during electroporation procedures may help to overcome the cancellation phenomenon; however, the exact thresholds are not yet known. Therefore, in this work, we have tested the influence of different interphase delay values (from 0 ms to 95 ms) using symmetric bipolar nanoseconds (300 and 500 ns) on cell permeabilization using 10 Hz, 100 Hz, and 1 kHz protocols. As a model mouse hepatoma, the MH-22a cell line was employed. Additionally, we conducted in vitro electrochemotherapy with cisplatin, employing reduced interphase delay values (0 ms and 0.1 ms) at 10 Hz. Cell plasma membrane permeabilization and viability dependence on a variety of bipolar pulsed electric field protocols were characterized. It was shown that it is possible to minimize bipolar cancellation, enabling treatment efficiency comparable to monophasic pulses with identical parameters. At the same time, it was highlighted that bipolar cancellation has a significant influence on permeabilization, while the effects on the outcome of electrochemotherapy are minimal.

Electrochemotherapy with intravenous, intratumoral, or combined administration of bleomycin in the treatment of colorectal hepatic metastases in a rat model.

Electrochemotherapy (ECT) combines the reversible electroporation (rEP) with intravenous (i.v.) or intratumoral (i.t.) administration of chemotherapeutic drugs. We conducted this study to compare the efficacy of i.v., i.t., and i.v. + i.t. injection of bleomycin (BLM) in ECT treatment of colorectal hepatic metastases in a rat model. WAG/Rij rats were randomized into three groups and underwent ECT with i.v., i.t., or i.v. + i.t. injection of BLM. Tumor volumes and oxygenation were measured by means of ultrasound and photoacoustic imaging. Moreover, liver and tumor tissue were analyzed by histology and immunohistochemistry. The i.v. and i.v. + i.t. groups exhibited a 44.0% and 46.6% reduction in oxygen saturation of the tumor tissue when compared to pretreatment values, whereas the i.t. group only showed a reduction of 35.2%. The extent of tumor tissue necrosis did not statistically differ between the groups. However, the i.t. group showed a tendency towards a lower necrosis rate. Cell proliferation, apoptotic cell death, vascularization, and immune cell infiltration were comparable in the treated tumors of the three groups. ECT with i.v. administration of BLM should be preferred in clinical practice, as the combined i.v. + i.t. therapy did not show superior oncological outcomes in the present study.

Comparison of Three Chemotherapy Protocols With Electrochemotherapy for the Treatment of Feline Cutaneous Squamous Cell Carcinoma.

Electrochemotherapy (ECT) with intravenous (IV) and/or intratumoral (IT) bleomycin has shown considerable efficacy in the treatment of non-resectable feline cutaneous squamous cell carcinoma (cSCC), boasting response rates of up to 95%, but other chemotherapy protocols have not yet been investigated. The objective of this prospective multicentre study was to compare the overall response rate (ORR) and progression-free interval (PFI) between cats with cSCC treated with ECT using IT and IV carboplatin (IV + IT), IV carboplatin (IV) or IV bleomycin (IV). A total of 44 cats with unresectable cSCC across three centres were enrolled and treated with ECT using carboplatin IV + IT (n = 10), carboplatin IV (n = 11) or bleomycin IV (n = 23). Treatment response according to RECIST criteria was recorded at 2 and 4 weeks post-treatment, and patients were followed until disease progression and/or death. All three groups were comparable regarding age, sex, weight, and lesion size. Adverse events were generally mild, localised and similar between groups. ORRs were 90.0% (carboplatin IV + IT), 90.9% (carboplatin IV) and 95.6% (bleomycin IV) and were not significantly different (p = 0.79). Median PFI was not reached for carboplatin IV + IT or carboplatin IV and was 566 days for bleomycin IV, with no significant difference between the three groups (p = 0.81). This study suggests that ECT using IV or IV + IT carboplatin is a reasonable alternative therapeutic option for managing cSCC, and further studies are warranted to compare outcomes between treatment protocols.

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.

Electrochemotherapy (ECT) in treatment of mucosal head and neck tumors. An international network for sharing practices on ECT (InspECT) study group report.

The aim of this multicenter study was to evaluate the effectiveness and safety of electrochemotherapy (ECT) for the treatment of mucosal tumors in the head and neck. A total of 71 patients with 84 nodules of different histologies in the oral cavity, pharynx and larynx treated by ECT were evaluated. The data were collected from the InspECT database from 10 participating centers throughout Europe. Primary and recurrent/secondary tumors of different histologies were treated. The overall response rate was 65 %, with a 33 % complete response rate with limited side effects. The response rates of the primary and secondary tumors were not different. However, smaller tumors responded better than tumors larger than 3 cm in diameter. Furthermore, the tumors that were treated with curative intent responded significantly better than those treated with palliative intent. This study demonstrated the feasibility, safety and effectiveness of ECT in a larger cohort of patients with mucosal lesions in the head and neck region. Based on the available data, ECT can be used for the treatment of recurrent and, in some cases, primary mucosal tumors located in the oral cavity, larynx, and pharynx. A better response was obtained in patients with smaller primary tumors treated with curative intent.

Treatment benefit of electrochemotherapy for superficial squamous cell carcinoma: a systematic review and single-arm meta-analysis.

OBJECTIVE: Treating aggressive superficial squamous cell carcinoma (SCC) poses challenges due to invasiveness. Palliative care is recommended for inoperable cases with extensive tumors near vital organs, risking disfigurement or functional impairment. Electrochemotherapy (ECT) is an emerging cutaneous tumor treatment, but its efficacy against superficial SCC remains uncertain. This study conducts a systematic review and single-arm meta-analysis to evaluate ECT's effectiveness against superficial SCC and provide current evidence for clinical practice. METHODS: Embase, PubMed and Cochrane Library were searched for studies up to May 2023. The random effects model analyzed complete response (CR) and partial response (PR), with subgroup assessment based on drug dosage, treatment response evaluation, tumor size, primary/recurrent status, and tumor location. RESULTS: Ten studies involving 162 patients and 208 tumors were included. Pooled CR and PR rates for ECT-treated superficial SCC were 66.5% (95% CI 48.4%-82.5%; I2 = 84%) and 20.3% (95% CI 10.5%-32.3%; I2 = 70%), respectively. Subgroup analysis indicated ECT's superiority in treating primary tumors (PR: 70%, CR: 30%) and tumors ≤ 3 cm (PR: 81.3%, CR: 10.1%) compared to recurrent tumors (PR: 56.7%, CR: 36.5%) and tumors > 3 cm (PR: 45.2%, CR: 34.4%). CONCLUSION: This single-arm meta-analysis confirms ECT's efficacy against superficial SCC, especially in primary tumors and those ≤ 3 cm in diameter. The study highlights the impact of tumor location and response evaluation on ECT's benefits, warranting further investigation through additional research.

Treatment of vulvar cancer recurrence with electrochemotherapy: a case-control study.

BACKGROUND: Electrochemotherapy (ECT) is a combined treatment method based on electroporation and simultaneous chemotherapy. In cases where radiotherapy has previously been used, surgery is often the only treatment option for vulvar cancer recurrence with potential resection of clitoris, vagina, urethra or anal sphincter. The unique advantage of ECT is its selectivity for cancer cells while sparing the surrounding healthy tissue. The aim of the study was to compare the ECT treatment of vulvar cancer recurrence for non-palliative purposes with surgical treatment. MATERIALS AND METHODS: Eleven patients with single vulvar cancer recurrence were treated with ECT and followed up for 12 months. As a control group, 15 patients with single vulvar cancer recurrence were treated with wide local excision. The following data were collected, analyzed and compared: Age, body mass index, comorbidities, histological type, location and size of vulvar cancer recurrence, treatment history, details of procedures and hospital stay. RESULTS: The probability curves for local tumor control did not differ between the ECT group and the surgical group (p = 0.694). The mean hospital stay and the mean duration of procedure were statistically significantly shorter in the ECT group (p < 0.001). There were no statistically significant differences between the ECT and surgical groups in terms of mean body mass index, associated diseases, previous treatments, presence of lichen sclerosus, p16 status, gradus, anatomical site of the tumor, and type of anesthesia. CONCLUSION: In this case-control study, treatment of vulvar cancer recurrence with ECT for non-palliative purposes was comparable to surgical treatment in terms of effectiveness. The results need to be confirmed in larger randomized trials.

Immune cell populations in the tumour environment following calcium electropora-tion for cutaneous metastasis: a histopathological study.

BACKGROUND AND PURPOSE: Calcium electroporation (CaEP) involves injecting calcium into tumour tissues and using electrical pulses to create membrane pores that induce cell death. This study assesses resultant immune responses and histopathological changes in patients with cutaneous metastases. PATIENTS/MATERIALS AND METHODS: The aimed cohort comprised 24 patients with metastases exceeding 5 mm. Tumours were treated once with CaEP (day 0) or twice (day 28). Biopsies were performed on days 0 and 2, with additional samples on days 7, 28, 30, 35, 60, and 90 if multiple tumours were treated. The primary endpoint was the change in tumour-infiltrating lymphocytes (TILs) two days post-treatment, with secondary endpoints evaluating local and systemic immune responses via histopathological analysis of immune markers, necrosis, and inflammation. RESULTS: Seventeen patients, with metastases primarily from breast cancer (14 patients), but also lung cancer (1), melanoma (1), and urothelial cancer (1), completed the study. Of the 49 lesions treated, no significant changes in TIL count or PD-L1 expression were observed. However, there was substantial necrosis and a decrease in FOXP3-expression (p = 0.0025) noted, with a slight increase in CD4+ cells but no changes in CD3, CD8, or CD20 expressions. Notably, four patients showed reduced tumour invasiveness, including one case of an abscopal response. INTERPRETATION: This exploratory study indicates that CaEP can be an effective anti-tumour therapy potentially enhancing immunity. Significant necrosis and decreased regulatory lymphocytes were observed, although TIL count remained unchanged. Several patients exhibited clinical signs of immune response following treatment.

An Explorative Study on Calcium Electroporation for Low-risk Basal Cell Carcinoma.

In electrochemotherapy, permeabilization of the cell membrane by electric pulses increases the anti-tumour effect of chemotherapeutics. In calcium electroporation, chemotherapy is replaced by calcium chloride with obvious benefits. This study explores the effect and underlying mechanisms of calcium electroporation on basal cell carcinomas using either high- or low-frequency electroporation. Low-risk primary basal cell carcinomas were treated in local anaesthesia with intratumoral calcium chloride followed by electroporation with high (167 kHz) or low (5 kHz) frequencies. Non-complete responders were retreated after 3 months. The primary endpoint was tumour response 3 months after last calcium electroporation. Plasma membrane calcium ATPase was examined in various cell lines as plasma membrane calcium ATPase levels have been associated with calcium electroporation efficacy. Twenty-two out of 25 included patients complete the study and 7 of these (32%) achieved complete response at 3 months with no difference in efficacy between high- and low-frequency pulses. High-frequency calcium electroporation was significantly less painful (p=0.03). Plasma membrane calcium ATPase was increased 16-32-fold in basal cell carcinoma cell lines compared with 4 other cancer cell lines. Calcium electroporation for low-risk basal cell carcinomas does not fulfil the requirements of a new dermatological basal cell carcinoma treatment but may be useful as adjuvant treatment to surgery in more advanced basal cell carcinomas. The elevated PMCA levels in basal cell carcinomas may contribute to low efficacy.

Treatment of Spontaneous Tumors With Algorithmically Controlled Electroporation.

OBJECTIVE: To study the safety and efficacy of algorithmically controlled electroporation (ACE) against spontaneous equine melanoma. METHODS: A custom temperature sensing coaxial electrode was paired with a high voltage pulse generation system with integrated temperature feedback controls. Computational modeling and ex vivo studies were conducted to evaluate the system's ability to achieve and maintain target temperatures. Twenty-five equine melanoma tumors were treated with a 2000 V protocol consisting of a 2-5-2 waveform, 45 °C temperature set point, and integrated energized times of 0.005 s, 0.01 s, or 0.02 s (2500x, 5000x, and 10000x 2 µs pulses, respectively). Patients returned 20-50 days post treatment to determine the efficacy of the treatment. RESULTS: ACE temperature control algorithms successfully achieved and maintained target temperatures in a diverse population of spontaneous tumors with significant variation in tissue impedance. All treatments were completed successfully without and without adverse events. Complete response rates greater than 93% were achieved in all treatment groups. CONCLUSION: ACE is a safe and effective treatment for spontaneous equine melanoma. The temperature control algorithm enabled rapid delivery of electroporation treatments without prior knowledge of tissue electrical or thermal properties and could adjust to real time changes in tissue properties. SIGNIFICANCE: Real time temperature control in electroporation procedures enables treatments near critical structures where thermal damage is contraindicated. Unlike standard approaches, ACE protocols do not require extensive pretreatment planning or knowledge of tissue properties to determine an optimal energy delivery rate and they can account for changes in tissue state (e.g., perfusion) in real time to simultaneously minimize treatment time and potential for thermal damage.

Outcome of bleomycin electrosclerotherapy of slow-flow malformations in adults and children.

OBJECTIVES: To evaluate the safety and clinical outcome of bleomycin electrosclerotherapy (BEST) for treating extracranial slow-flow malformations. METHODS: In this retrospective investigation of a multicenter cohort presenting symptomatic slow-flow malformations, patient records were analyzed with respect to procedural details and complications. A treatment-specific, patient-reported questionnaire was additionally evaluated, obtained 3-12 months after the last treatment, to assess the subjective outcomes, including mobility, aesthetic aspects, and pain, as well as the occurrence of postprocedural skin hyperpigmentation. All outcome parameters were compared according to patients' age. RESULTS: Overall, 325 BEST treatments were performed in 233 patients after intralesional and/or intravenous bleomycin injection. The total complication rate was 10.2% (33/325), including 29/352 (8.9%) major complications. Patient-reported mobility decreased in 10/133 (8.8%), was stable in 30/113 (26.5%), improved in 48/113 (42.5%), and was rated symptom-free in 25/113 (22.1%) patients. Aesthetic aspects were rated impaired compared to baseline in 19/113 (16.8%), stable in 21/133 (18.6%), improved in 62/113 (54.9%), and perfect in 11/133 (9.7%) patients. Postprocedural skin hyperpigmentation occurred in 78/113 (69%) patients, remaining unchanged in 24/78 (30.8%), reduced in 51/78 (65.5%), and completely resolved in 3/78 (3.8%) patients. The median VAS pain scale was 4.0 (0-10) preprocedural and 2.0 (0-9) postprocedural. Children/adolescents performed significantly better in all parameters compared to adults (≥ 16 years) (mobility, p = 0.011; aesthetic aspects, p < 0.001; pain, p < 0.001). CONCLUSIONS: BEST is effective for treating slow-flow vascular malformations, with few but potentially significant major complications. Regarding patient-reported outcomes, children seem to benefit better compared to older patients, suggesting that BEST should not be restricted to adults. CLINICAL RELEVANCE STATEMENT: Bleomycin electrosclerotherapy is a safe and effective approach and therapy should not be restricted to adults due to good clinical outcomes in children.

Electrochemotherapy as adjuvant treatment in a sinonasal mucosal melanoma in elderly patient: a case report.

BACKGROUND: Sinonasal Mucosal Melanoma (SNMM) is a rare but aggressive disease. Surgery with free margins, when feasible, is the treatment of choice. In the last three decades, electrochemotherapy (ECT) has emerged as a local ablative procedure, performed with the Cliniporator, for cutaneous and mucosal tumours of different histology. We present a case report of an ECT treatment performed by means of a new endoscopic electrode, on an elderly patient affected by primary SNMM. METHODS: An 88-year-old man with a diagnosis of SNMM (cT4aN0M0)-Stage IV, of the left nasal fossa presented at our institution. Symptoms were epistaxis and complete left nasal obstruction. He refused sinonasal extended surgery and radiotherapy. He underwent a tumor debulking followed by ECT exclusively for symptom control, with palliative intent. RESULTS: The patient underwent SNMM debulking under general anaesthesia, followed by ECT on tumour margins. After the procedure, he had been free from symptoms for 5 months, with a good quality of life. Local recurrence was controlled with a new local debulking and ECT procedure on margins. The patient remained symptom free for the next 4 months. Seventeen months after diagnosis, the patient is mild symptomatic for sinonasal disease. Therefore, he developed a systemic disease progression. CONCLUSIONS: In our experience, ECT can be used as an adjuvant tool for symptom and local control in SNMM when extended surgery is out of curative intent or unfeasible. As expected, ECT does not appear to have any effect on systemic disease progression.

The equivalence of different types of electric pulses for electrochemotherapy with cisplatin - an in vitro study.

BACKGROUND: Electrochemotherapy (ECT) is a treatment involving the administration of chemotherapeutics drugs followed by the application of 8 square monopolar pulses of 100 µs duration at a repetition frequency of 1 Hz or 5000 Hz. However, there is increasing interest in using alternative types of pulses for ECT. The use of high-frequency short bipolar pulses has been shown to mitigate pain and muscle contractions. Conversely, the use of millisecond pulses is interesting when combining ECT with gene electrotransfer for the uptake of DNA-encoding proteins that stimulate the immune response with the aim of converting ECT from a local to systemic treatment. Therefore, the aim of this study was to investigate how alternative types of pulses affect the efficiency of the ECT. MATERIALS AND METHODS: We performed in vitro experiments, exposing Chinese hamster ovary (CHO) cells to conventional ECT pulses, high-frequency bipolar pulses, and millisecond pulses in the presence of different concentrations of cisplatin. We determined cisplatin uptake by inductively coupled plasma mass spectrometry and cisplatin cytotoxicity by the clonogenic assay. RESULTS: We observed that the three tested types of pulses potentiate the uptake and cytotoxicity of cisplatin in an equivalent manner, provided that the electric field is properly adjusted for each pulse type. Furthermore, we quantified that the number of cisplatin molecules, resulting in the eradication of most cells, was 2-7 × 107 per cell. CONCLUSIONS: High-frequency bipolar pulses and millisecond pulses can potentially be used in ECT to reduce pain and muscle contraction and increase the effect of the immune response in combination with gene electrotransfer, respectively.

Integrated Time Nanosecond Pulse Irreversible Electroporation (INSPIRE): Assessment of Dose, Temperature, and Voltage on Experimental and Clinical Treatment Outcomes.

OBJECTIVE: This study sought to investigate a novel strategy using temperature-controlled delivery of nanosecond pulsed electric fields as an alternative to the 50-100 microsecond pulses used for irreversible electroporation. METHODS: INSPIRE treatments were carried out at two temperatures in 3D tumor models using doses between 0.001 s and 0.1 s. The resulting treatment zones were quantified using viability staining and lethal electric field intensities were determined numerically. Computational modeling was then used to determine parameters necessary for INSPIRE treatments to achieve equivalent treatment zones to clinical electroporation treatments and evaluate the potential for these treatments to induce deleterious thermal damage. RESULTS: Lethal thresholds between 1109 and 709 V/cm were found for nominal 0.01 s treatments with pulses between 350 ns and 2000 ns at physiological temperatures. Further increases in dose resulted in significant decreases in lethal thresholds. Given these experimental results, treatment zones comparable to clinical electroporation are possible by increasing the dose and voltage used with nanosecond duration pulses. Temperature-controlled simulations indicate minimal thermal cell death while achieving equivalent treatment volumes to clinical electroporation. CONCLUSION: Nanosecond electrical pulses can achieve comparable outcomes to traditional electroporation provided sufficient electrical doses or voltages are applied. The use of temperature-controlled delivery may minimize thermal damage during treatment. SIGNIFICANCE: Intense muscle stimulation and the need for cardiac gating have limited irreversible electroporation. Nanosecond pulses can alleviate these challenges, but traditionally have produced significantly smaller treatment zones. This study suggests that larger ablation volumes may be possible with the INSPIRE approach and that future in vivo studies are warranted.

Intraoperative electrochemotherapy of the posterior resection surface after pancreaticoduodenectomy: Preliminary results of a hybrid approach treatment of pancreatic cancer.

BACKGROUND: Despite extensive research in recent decades, pancreatic cancer continues to be among the most lethal forms of cancer, with no substantial increase in survival rates. Local recurrences account for approximately 30 per cent of all disease recurrences. With the intent to improve survival, we designed a novel, hybrid treatment strategy consisting of surgical resection and additional intraoperative electrochemotherapy of the posterior resection surface. We present the study protocols and preliminary findings of a prospective pilot study investigating this treatment approach. METHODS: Consenting patients with resectable pancreatic head ductal adenocarcinoma who met the inclusion criteria were enrolled in the study. After surgical resection, electrochemotherapy with bleomycin was performed using plate electrodes to cover the area between anatomical landmarks. RESULTS: Electrochemotherapy of the posterior resection surface was feasible in all 7 patients. We observed pancreatic fistula grade B in only one patient; all other noted complications were Clavien-Dindo grade 2 or less. The hospital mortality was 0%. CONCLUSIONS: Our preliminary results suggest that a hybrid approach combining surgery with intraoperative electrochemotherapy is safe and feasible.

Negative effects of cancellation during nanosecond range High-Frequency calcium based electrochemotherapy in vitro.

Drug delivery using nanosecond pulsed electric fields is a new branch of electroporation-based treatments, which potentially can substitute European standard operating procedures for electrochemotherapy. In this work, for the first time, we characterize the effects of ultra-fast repetition frequency (1-2.5 MHz) nanosecond pulses (5-9 kV/cm, 200 and 400 ns) in the context of nano-electrochemotherapy with calcium. Additionally, we investigate the feasibility of bipolar symmetric (↑200 ns + ↓200 ns) and asymmetric (↑200 ns + ↓400 ns) nanosecond protocols for calcium delivery. The effects of bipolar cancellation and the influence of interphase delay (200 ns) are overviewed. Human lung cancer cell lines A549 and H69AR were used as a model. It was shown that unipolar pulses delivered at high frequency are effective for electrochemotherapy with a significant improvement in efficiency when the delay between separate pulses is reduced. Bipolar symmetric pulses trigger the cancellation phenomenon limiting applications for drug delivery and can be compensated by the asymmetry of the pulse (↑200 ns + ↓400 ns or ↑400 ns + ↓200 ns). The results of this study can be successfully used to derive a new generation of nsPEF protocols for successful electrochemotherapy treatments.

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.

Effects of pulse repetition rate in static electrochemotherapy models.

Electroporation alters cell membrane structure and tissue electrical properties by short and intense pulsed electric fields (PEF). Static mathematical models are often used to explain the change in electrical properties of tissues caused by electroporation. Electric pulse repetition rate may play an important role, as tissue dielectric dispersion, electroporation dynamics, and Joule heating may affect the electrical properties. In this work, we investigate the effects on the magnitude of the electric current when the repetition rate of the standard electrochemotherapy protocol is increased. Liver, oral mucosa, and muscle tissues were studied. Ex vivo animal experiments show that the magnitude of the electric current increases when the repetition rate is changed from 1 Hz to 5 kHz (10.8% for liver, 5.8% for oral mucosa, and 4.7% for muscle). Although a correction factor could reduce the error to less than 1%, dynamic models seem to be necessary to analyze different protocol signatures. Authors should be aware that static models and experimental results can only be compared if they use exactly the same PEF signature. The repetition rate is a key information to consider in the pretreatment computer study because the current at 1 Hz PEF differs from a 5 kHz PEF.

Electrochemotherapy vs radiotherapy in the treatment of primary cutaneous malignancies or cutaneous metastases from primary solid organ malignancies: A systematic review and narrative synthesis.

BACKGROUND: Electrochemotherapy has gained international traction and commendation in national guidelines as an effective tool in the management of cutaneous malignancies not amenable to surgical resection. Despite this, no level 5 evidence exists comparing it to radiotherapy in the treatment of cutaneous malignancies. This systematic review aimed to examine the literature directly and indirectly comparing electrochemotherapy and radiotherapy in the treatment of primary cutaneous malignancies or cutaneous metastases from primary solid organ malignancies. MATERIALS & METHODS: The protocol for this review was registered on the PROSPERO International Prospective Register of Systematic Reviews with the protocol ID CRD42021285415. Searches of MEDLINE, Embase, CINAHL, CENTRAL and ClinicalTrials.gov databases were undertaken from database inception to 28 December 2021. Studies in humans comparing treatment with electrochemotherapy to radiotherapy and reporting tumour response with a minimum four week follow-up were eligible. Risk of bias was assessed using the ROBINS-I tool. Results are provided as a narrative synthesis. RESULTS: Two case series with a total of 92 patients were identified as relevant to this study. Both case series examined patients with cutaneous squamous cell carcinoma. One case series examined elderly patients with predominantly head/neck lesions. The other examined younger patients with predominantly limb lesions who had cutaneous squamous cell carcinoma directly attributable to a rare skin condition. CONCLUSION: There is little literature presenting comparative data for electrochemotherapy and radiotherapy in the treatment of primary cutaneous malignancies or cutaneous metastases. Included studies were marred by serious risk of bias particularly due to confounding. The inherent bias and heterogeneity of the included studies precluded synthesis of a consolidated comparison of clinical outcomes between the two therapies. Further research is required in this domain in the form of clinical trials and observational studies to inform guidelines for electrochemotherapy treatment.