The effectiveness of calcium electroporation combined with gene electrotransfer of a plasmid encoding IL-12 is tumor type-dependent.

Introduction: In calcium electroporation (CaEP), electroporation enables the cellular uptake of supraphysiological concentrations of Ca2+, causing the induction of cell death. The effectiveness of CaEP has already been evaluated in clinical trials; however, confirmatory preclinical studies are still needed to further elucidate its effectiveness and underlying mechanisms. Here, we tested and compared its efficiency on two different tumor models to electrochemotherapy (ECT) and in combination with gene electrotransfer (GET) of a plasmid encoding interleukin-12 (IL-12). We hypothesized that IL-12 potentiates the antitumor effect of local ablative therapies as CaEP and ECT. Methods: The effect of CaEP was tested in vitro as well as in vivo in murine melanoma B16-F10 and murine mammary carcinoma 4T1 in comparison to ECT with bleomycin. Specifically, the treatment efficacy of CaEP with increasing calcium concentrations alone or in combination with IL-12 GET in different treatment protocols was investigated. We closely examined the tumor microenvironment by immunofluorescence staining of immune cells, as well as blood vessels and proliferating cells. Results: In vitro, CaEP and ECT with bleomycin reduced cell viability in a dose-dependent manner. We observed no differences in sensitivity between the two cell lines. A dose-dependent response was also observed in vivo; however, the efficacy was better in 4T1 tumors than in B16-F10 tumors. In 4T1 tumors, CaEP with 250 mM Ca resulted in more than 30 days of growth delay, which was comparable to ECT with bleomycin. In contrast, adjuvant peritumoral application of IL-12 GET after CaEP prolonged the survival of B16-F10, but not 4T1-bearing mice. Moreover, CaEP with peritumoral IL-12 GET modified tumor immune cell populations and tumor vasculature. Conclusions: Mice bearing 4T1 tumors responded better to CaEP in vivo than mice bearing B16-F10 tumors, even though a similar response was observed in vitro. Namely, one of the most important factors might be involvement of the immune system. This was confirmed by the combination of CaEP or ECT with IL-12 GET, which further enhanced antitumor effectiveness. However, the potentiation of CaEP effectiveness was also highly dependent on tumor type; it was more pronounced in poorly immunogenic B16-F10 tumors compared to moderately immunogenic 4T1 tumors.

Outcomes of older adults aged 90 and over with cutaneous malignancies after electrochemotherapy with bleomycin: A matched cohort analysis from the InspECT registry.

BACKGROUND: With extending life expectancy, more people are diagnosed with cutaneous malignancies at advanced ages and are offered nonsurgical treatment. We assessed outcomes of the oldest-old adults after electrochemotherapy (ECT). METHODS: The International Network for Sharing Practices of ECT (InspECT) registry was queried for adults aged ≥90 years (ys) with skin cancers/cutaneous metastases of any histotype who underwent bleomycin-ECT (2006-2019). These were subanalysed with patients aged <90 ys after matching 1:2 for tumor location, number, size, histotype, and previous treatments. We assessed ECT modalities, toxicity (CTCAE), response (RECIST), and patient perception (EQ-5D). RESULTS: Sixty-one patients represented the study cohort (median 92 ys, range 92-104), 122 the control group (median 77 ys, range 23-89). Among the oldest-old, 44 patients (72%) had primary/recurrent skin cancers, 17 (28%) cutaneous metastases. Median tumour size was 15 mm (range, 5-450). The oldest-old adults underwent ECT mainly under local/regional anaesthesia (59% vs 39% p = .012). We observed no differences regarding dose and route of chemotherapy (intravenous vs intratumoral, p = .308), electrode geometry (linear vs hexagonal, p = .172) and procedural duration (18 vs 21 min, p = .378). Complete response (57.4 [95%-CI 44.1%-70.0%] vs 64.7% [95%-CI 55.6%-73.2%], p = .222) and 1-year local control (76.7% vs 81.7, p = .092) rates were comparable. Pain and skin hyperpigmentation were mild in both groups. Skin ulceration persisted longer in the oldest-old patients (4.4 vs 2.4 months, p = .008). CONCLUSIONS: The oldest-old adults with cutaneous malignancies undergo ECT most commonly under local/regional anaesthesia with safety profiles and clinical effectiveness similar to their younger counterparts, except in case of ulcerated tumors.

Increased cellular uptake of biocompatible superparamagnetic iron oxide nanoparticles into malignant cells by an external magnetic field.

Superparamagnetic iron oxide nanoparticles (SPIONs) are used as delivery systems for different therapeutics including nucleic acids for magnetofection-mediated gene therapy. The aim of our study was to evaluate physicochemical properties, biocompatibility, cellular uptake and trafficking pathways of the custom-synthesized SPIONs for their potential use in magnetofection. Custom-synthesized SPIONs were tested for size, shape, crystalline composition and magnetic behavior using a transmission electron microscope, X-ray diffractometer and magnetometer. SPIONs were dispersed in different aqueous media to obtain ferrofluids, which were tested for pH and stability using a pH meter and zetameter. Cytotoxicity was determined using the MTS and clonogenic assays. Cellular uptake and trafficking pathways were qualitatively evaluated by transmission electron microscopy and quantitatively by inductively coupled plasma atomic emission spectrometry. SPIONs were composed of an iron oxide core with a diameter of 8-9 nm, coated with a 2-nm-thick layer of silica. SPIONs, dispersed in 0.9% NaCl solution, resulted in a stable ferrofluid at physiological pH for several months. SPIONs were not cytotoxic in a broad range of concentrations and were readily internalized into different cells by endocytosis. Exposure to neodymium-iron-boron magnets significantly increased the cellular uptake of SPIONs, predominantly into malignant cells. The prepared SPIONs displayed adequate physicochemical and biomedical properties for potential use in magnetofection. Their cellular uptake was dependent on the cell type, and their accumulation within the cells was dependent on the duration of exposure to an external magnetic field.

Cancer electrogene therapy with interleukin-12.

Electrogene therapy combines administration of plasmid DNA into tissue followed by local application of electric pulses. In electrogene therapy with interleukin-12 (IL-12), different routes of administration, different doses of plasmid DNA and different protocols for delivery of electric pulses were evaluated in numerous preclinical studies. Antitumor effectiveness was tested in different types of primary tumors, distantly growing tumors and induced metastases. Intratumoral IL-12 electrogene therapy has been proved to be very effective in local tumor control, having also a systemic effect. Intramuscular and peritumoral IL-12 electrogene therapy had also a pronounced systemic effect and when combined with other treatment strategies resulted in tumor cures. Antitumor effectiveness of IL-12 electrogene therapy is due to the induction of adaptive immunity and innate resistance and anti-angiogenic action. Translation of preclinical studies into clinical trials in human and veterinary oncology has started with encouraging results that would hopefully lead to further investigation of this therapy, also in combination with other cancer treatment modalities.

Towards treatment planning and treatment of deep-seated solid tumors by electrochemotherapy.

BACKGROUND: Electrochemotherapy treats tumors by combining specific chemotherapeutic drugs with an intracellular target and electric pulses, which increases drug uptake into the tumor cells. Electrochemotherapy has been successfully used for treatment of easily accessible superficial tumor nodules. In this paper, we present the first case of deep-seated tumor electrochemotherapy based on numerical treatment planning. METHODS: The aim of our study was to treat a melanoma metastasis in the thigh of a patient. Treatment planning for electrode positioning and electrical pulse parameters was performed for two different electrode configurations: one with four and another with five long needle electrodes. During the procedure, the four electrode treatment plan was adopted and the patient was treated accordingly by electrochemotherapy with bleomycin. The response to treatment was clinically and radiographically evaluated. Due to a partial response of the treated tumor, the metastasis was surgically removed after 2 months and pathological analysis was performed. RESULTS: A partial response of the tumor to electrochemotherapy was obtained. Histologically, the metastasis showed partial necrosis due to electrochemotherapy, estimated to represent 40-50% of the tumor. Based on the data obtained, we re-evaluated the electrical treatment parameters in order to correlate the treatment plan with the clinical response. Electrode positions in the numerical model were updated according to the actual positions during treatment. We compared the maximum value of the measured electric current with the current predicted by the model and good agreement was obtained. Finally, tumor coverage with an electric field above the reversible threshold was recalculated and determined to be approximately 94%. Therefore, according to the calculations, a small volume of tumor cells remained viable after electrochemotherapy, and these were sufficient for tumor regrowth. CONCLUSIONS: In this, the first reported clinical case, deep-seated melanoma metastasis in the thigh of the patient was treated by electrochemotherapy, according to a treatment plan obtained by numerical modeling and optimization. Although only a partial response was obtained, the presented work demonstrates that treatment of deep-seated tumor nodules by electrochemotherapy is feasible and sets the ground for numerical treatment planning-based electrochemotherapy. TRIAL REGISTRATION: EudraCT:2008-008290-54.

Effective treatment of perianal tumors in dogs with electrochemotherapy.

BACKGROUND: Electrochemotherapy is an antitumor therapy that utilizes locally-delivered, short intense direct current electric pulse to the tumor nodule plus chemotherapy. The aim of the present study was to evaluate the electrochemotherapy treatment of perianal tumors of different sizes in dogs. MATERIALS AND METHODS: In 12 dogs, 26 tumor nodules of perianal tumors of different size, and clinically expected to be of different histological type, were treated with electrochemotherapy. Electrochemotherapy consisted of intratumoral injection of cisplatin (1 mg/cm3) or bleomycin (3 mg/cm3), followed by application of electric pulses (8 electric pulses; amplitude, 910 V, duration, 100 micros, frequency, 1 Hz) to the tumor nodule. RESULTS: Responses to treatment were assessed 4 weeks after the therapy; 82% of all tumors treated with electrochemotherapy responded with objective response (OR) (complete response (CR)=41%, partial response (PR)=41%), 16% responded with no change (NC) and 1 tumor (2%) went to progressive disease (PD). At the end of the observation period for each tumor, ranging from 1 to 34 months, 92% OR (CR=65%, PR=27%), 8% NC and no PD were obtained. No major local or general side-effects were noted. CONCLUSION: Electrochemotherapy with cisplatin or bleomycin is an effective treatment of perianal tumors in dogs. The advantages of this therapy are its simplicity, short duration of treatment sessions, low chemotherapeutic doses and insignificant side-effects, as well as the fact that the subject does not have to stay in hospital.

Antitumour effectiveness of hyperthermia is potentiated by local application of electric pulses to LPB tumours in mice.

BACKGROUND: The aim of our study was to determine whether local application of electric pulses to tumours, which induce transient reduction of tumour perfusion, could potentiate the antitumour effectiveness of hyperthermia. MATERIALS AND METHODS: The antitumour effectiveness of local application of electric pulses (1300 V/cm, 100 micros, 1 Hz) and 910 MHz local hyperthermia at 43.5 degrees C, alone or in combination, was determined on LPB tumours in C57Bl/6 mice by measurement of tumour growth delay, changes in tumour perfusion using the Patent blue technique and extent of tumour necrosis. RESULTS: When hyperthermia was performed immediately after application of electric pulses, at a time of maximally reduced tumour perfusion, greater than additive antitumour effectiveness was observed, resulting in 14.5 +/- 3.1 days growth delay of tumours that regrew and 43% complete responses. Single treatment, application of electric pulses or hyperthermia had minor or no effect on tumour growth. When hyperthermia was performed 24 hours after application of electric pulses, at a point when tumour perfusion was restored, the effect of both treatments was additive, resulting in 4.1 +/- 1.1 days growth delay and no cures. CONCLUSION: The probable mechanisms for the observed, more than additive, interaction when hyperthermia was performed immediately after application of electric pulses are the potentiation of thermic cytotoxicity, due to the reduced tumour perfusion induced by application of electric pulses and prolonged tumour perfusion reduction after combined treatment leading to additional cell kill, due to the protracted ischemia.

Perturbation of blood flow as a mechanism of anti-tumour action of direct current electrotherapy.

Anti-tumour effects of direct current electrotherapy are attributed to different mechanisms depending on the electrode configuration and on the parameters of electric current. The effects mostly arise from the electrochemical products of electrolysis. Direct toxicity of these products to tumour tissue is, however, not a plausible explanation for the observed tumour growth retardation in the case when the electrodes are placed into healthy tissue surrounding the tumour and not into the tumour itself. The hypothesis that the anti-tumour effectiveness of electrotherapy could result from disturbed blood flow in tumours was tested by the measurement of changes in blood perfusion and oxygenation in tumours with three different methods (in vivo tissue staining with Patent Blue Violet dye, polarographic oximetry, near-infrared spectroscopy). The effects induced by electrotherapy were evaluated in two experimental tumour models: Sa-1 fibrosarcoma in A/J mice and LPB fibrosarcoma in C57B1/6 mice. We found that perfusion and oxygenation were significantly decreased after electrotherapy. Good agreement between the results of different methods was observed. The effect of electrotherapy on local perfusion of tumours is probably the prevalent mechanism of anti-tumour action for the particular type of electrotherapy used in the study. The importance of this effect should be considered for the optimization of electrotherapy protocols in experimental and clinical trials. The non-invasive technique of near-infrared spectroscopy proved to be a reliable method for detecting perfusion and oxygenation changes in small solid tumours.