Electrochemotherapy can eradicate established colorectal carcinoma and leaves a systemic protective memory in mice

Palliative Treatment of Esophageal Cancer Using Calcium Electroporation

Simple Summary

Calcium electroporation is a new cancer therapy wherein a high, rapid influx of calcium, facilitated by electrical pulses, is used to kill cancer cells. This pilot study aimed to evaluate the safety and feasibility of this new treatment for patients with non-curable esophageal cancer. The treatment was administrated during an endoscopic examination, under general anesthesia, and in an outpatient setting. Eight patients were treated. One severe adverse event occurred (requiring a single blood transfusion) and another three mild side effects were seen. Two patients reported dysphagia relief after treatment and one patient had a partial response evaluated by CT. Six months after treatment, the same patient was still in good condition, without the need for further treatment. Calcium electroporation was conducted in eight patients with only a few side effects. More studies are warranted to evaluate clinical efficacy.

Abstract

Calcium electroporation (CaEP) is a novel cancer therapy wherein high intracellular calcium levels, facilitated by reversible electroporation, trigger tumor necrosis. This study aimed to establish safety with CaEP within esophageal cancer. Patients with non-curable esophageal cancer were included at Copenhagen University Hospital Rigshospitalet in 2021 and 2022. In an outpatient setting, calcium gluconate was injected intratumorally followed by reversible electroporation applied with an endoscopic electrode. The primary endpoint was the prevalence of adverse events, followed by palliation of dysphagia. All patients were evaluated with CT and upper endoscopies up to two months after treatment. The trial was registered at ClinicalTrials.gov (NCT04958044). Eight patients were treated. One serious adverse event (anemia, requiring a single blood transfusion) and three adverse events (mild retrosternal pain (two) and oral thrush (one)) were registered. Initially, six patients suffered from dysphagia: two reported dysphagia relief and four reported no change. From the imaging evaluation, one patient had a partial response, three patients had no response, and four patients had progression. Six months after treatment, the patient who responded well was still in good condition and without the need for further oncological treatment. CaEP was conducted in eight patients with only a few side effects. This study opens the way for larger studies evaluating tumor regression and symptom palliation.

Local Destruction of Tumors and Systemic Immune Effects

Current immune-based therapies signify a major advancement in cancer therapy; yet, they are not effective in the majority of patients. Physically based local destruction techniques have been shown to induce immunologic effects and are increasingly used in order to improve the outcome of immunotherapies. The various local destruction methods have different modes of action and there is considerable variation between the different techniques with respect to the ability and frequency to create a systemic anti-tumor immunologic effect. Since the abscopal effect is considered to be the best indicator of a relevant immunologic effect, the present review focused on the tissue changes associated with this effect in order to find determinants for a strong immunologic response, both when local destruction is used alone and combined with immunotherapy. In addition to the T cell-inflammation that was induced by all methods, the analysis indicated that it was important for an optimal outcome that the released antigens were not destroyed, tumor cell death was necrotic and tumor tissue perfusion was at least partially preserved allowing for antigen presentation, immune cell trafficking and reduction of hypoxia. Local treatment with controlled low level hyperthermia met these requisites and was especially prone to result in abscopal immune activity on its own.

Calcium electroporation induces tumor eradication, long-lasting immunity and cytokine responses in the CT26 colon cancer mouse model

Electroporation is used in cancer treatment because of its ability to increase local cytotoxicity of e.g. bleomycin (electrochemotherapy) and calcium (calcium electroporation). Calcium electroporation is a novel anticancer treatment that selectively kills cancer cells by necrosis, a cell death pathway that stimulates the immune system due to high release of antigens and "danger signals." In this exploratory study, we aimed to investigate whether calcium electroporation could initiate an anticancer immune response similar to electrochemotherapy. To this end, we treated immunocompetent balb/c mice with CT26 colon tumors with calcium electroporation, electrochemotherapy, or ultrasound-based delivery of calcium or bleomycin. High treatment efficiency was observed with 100% complete remission in all four groups (12/12 with complete remission in each treatment group). In addition, none of the surviving mice from these groups formed new tumors when re-challenged with CT26 cancer cells 100-d post treatment, whereas mice challenged with different cancer cells (4T1 breast cancer) all developed tumors. Treatment of immunodeficient mice with calcium electroporation and electrochemotherapy showed no long-lasting tumor response. Calcium electroporation and electrochemotherapy was associated with a release of High Mobility Group Box 1 protein (HMGB1) in vitro (p = 0.029) and a significant increase of the overall systemic level of pro-inflammatory cytokines in serum from the treated mice (p < 0.003). These findings indicate that calcium electroporation as well as electrochemotherapy could have a role as immune stimulators in future treatments.

Electrochemotherapy induces apoptotic death in melanoma metastases: a histologic and immunohistochemical investigation

Background

Electrochemotherapy (ECT) is increasingly used in the treatment of primary and secondary skin tumors, but little is known about the pathologic mechanism responsible for tumor cell destruction in humans. Knowledge of detailed mechanism of host response after ECT may improve the treatment efficacy related to patient selection and technique refinements.

Aim

The aim of the study was to investigate the histopathology and mechanism of cell death after ECT in cutaneous melanoma metastases.

Methods

Skin biopsy specimens were sequentially obtained after ECT of cutaneous melanoma metastases, during a follow-up period of 2 months. Results from histologic evaluation and immunohistochemical characterization of the inflammatory infiltrate (CD3, CD4, CD8, CD56, Granzyme-B) were compared with a panel of apoptosis-related markers.

Main outcome measures

Evidence of the mechanism of tumor cell damage, identification of histological and immunohistochemical signs of apoptosis and/or necrosis underlining a possible time course of tumor destruction and inflammatory reaction after ECT.

Results

Early signs of epidermal degeneration, an increase of the inflammatory infiltrate, and initial tumor cell morphological changes were already detected 10 min after ECT. The cell damage progression, as demonstrated by histological and immunohistochemical evidence using apoptotic markers (TUNEL and caspase-3 staining), reached a climax 3 days after treatment, to continue until 10 days after. Scarring fibrosis and complete absence of tumor cells were observed in the late biopsy specimens. A rich inflammatory infiltrate with a prevalence of T-cytotoxic CD3/CD8-positive cells was detected 3 h after ECT and was still appreciable 3 months later.

Conclusion

This study attempts to define the time course and characteristics of tumor response to ECT. The observations suggest both a direct necrotic cell damage and a rapid activation of apoptotic mechanisms that occur in the early phases of the cutaneous reaction to ECT. A persistent immune response of T-cytotoxic lymphocytes could possibly explain the long-term local tumor control.

[Value of galvanotherapy for localised prostate cancer]

In recent years electrotherapy has become an accepted treatment option in several medical subfields such as defibrillation during cardiopulmonary resuscitation, electroconvulsive shock treatment (ECT) in conjunction with antidepressant therapy, pain management and physical therapy [transcutaneous electrical nerve stimulation (TENS), diathermia, Stanger bath therapy, etc.]. In recent years several groups, especially from Asia, have investigated the therapeutic effect of electricity in the treatment of malignant tumours. They determined basic principles of electrotherapy and developed different theories of tumour destruction. They postulated a multifactorial tissue effect of continuous current based on tumour cell necrosis due to pH shifting and alteration of membrane potential. In clinical trials similar oncological results of electrotherapy in several malignant tumours compared to established therapeutic methods were observed, whereas clinical trial designs to some extent were not consistent with internationally accepted scientific standards. Regarding electrotherapy of localised prostate cancer only limited data with a few cases and controversial study designs were published. According to EAU guidelines electrotherapy of localised prostate cancer as an alternative treatment option is not recommended and is still an experimental method. For this procedure well-designed clinical trials and a longer follow-up are mandatory to assess the true role of electrotherapy in the management of prostate cancer.

Effects and possible anti-tumor immunity of electrochemotherapy with bleomycin on human colon cancer xenografts in nude mice

AIM: To evaluate the anti-tumor effects and possible involvement of anti-tumor immunity of electrochemotherapy (ECT) employing electroporation and bleomycin in human colon cancer xenografts in nude mice, and to establish the experimental basis for clinical application of ECT.

METHODS: Forty nude mice, inoculated subcutaneously human colon cancer cell line LoVo for 3 wk, were allocated randomly into four groups: B+E+ (ECT), B+E- (administration of bleomycin alone), B-E+ (administration of electric pulses alone), and B-E- (no treatment). Tumor volumes were measured daily. The animals were killed on the 7^th d, the weights of xenografts were measured, and histologies of tumors were evaluated. Cytotoxicity of spleen natural killer (NK) and lymphokine-activated killer (LAK) cells was then assessed by lactic dehydrogenase release assay.

RESULTS: The mean tumor volume of group B+E+ was statistically different from the other three groups after the treatment (F = 36.80, P<0.01). There was one case of complete response, seven cases of partial response (PR) in group B+E+, one case of PR in group B+E- and group B-E+ respectively, and no response was observed in group B-E-. The difference of response between group B+E+ and the other three groups was statistically significant (χ² = 25.67, P<0.01). Histologically, extensive necrosis of tumor cells with considerable vascular damage and inflammatory cells infiltration were observed in group B+E+. There was no statistical difference between the cytotoxicity of NK and LAK cells in the four treatment groups.

CONCLUSION: ECT significantly enhances the chemosensitivity and effects of chemotherapy in human colon cancer xenografts in nude mice, and could be a kind of novel treatment modality for human colon cancer. The generation of T-cell-dependent, tumor-specific immunity might be involved in the process of ECT.