Modulated Electro-Hyperthermia Resolves Radioresistance of Panc1 Pancreas Adenocarcinoma and Promotes DNA Damage and Apoptosis In Vitro

The Synergy of Thermal and Non-Thermal Effects in Hyperthermic Oncology

BACKGROUND

Modulated electro-hyperthermia (mEHT) is unique due to its combination of thermal and non-thermal effects.

METHOD

This report summarizes the literature on the effects of mEHT observed in vitro and in vivo.

RESULTS

The thermal and electrical heterogeneity of tissues allows the radiofrequency signal to selectively target malignant tissue. The applied modulation appears to activate various apoptotic pathways, predominantly leading to immunogenic cell death (ICD). ICD promotes the release of damage-associated molecular patterns, potentially producing tumour-specific antigen-presenting cells. This abscopal-type effect may target distant metastases while treating the primary tumour locally. This immune memory effect is like vaccination mechanisms.

CONCLUSIONS

The application of mEHT has the potential to expand from local to systemic disease, enabling the simultaneous treatment of micro- and macro-metastases.

Pulsing Addition to Modulated Electro-Hyperthermia

Numerous preclinical results have been verified, and clinical results have validated the advantages of modulated electro-hyperthermia (mEHT). This method uses the nonthermal effects of the electric field in addition to thermal energy absorption. Modulation helps with precisely targeting and immunogenically destroying malignant cells, which could have a vaccination-like abscopal effect. A new additional modulation (high-power pulsing) further develops the abilities of the mEHT. My objective is to present the advantages of pulsed treatment and how it fits into the mEHT therapy. Pulsed treatment increases the efficacy of destroying the selected tumor cells; it is active deeper in the body, at least tripling the penetration of the energy delivery. Due to the constant pulse amplitude, the dosing of the absorbed energy is more controllable. The induced blood flow for reoxygenation and drug delivery is high enough but not as high as increasing the risk of the dissemination of malignant cells. The short pulses have reduced surface absorption, making the treatment safer, and the increased power in the pulses allows the reduction of the treatment time needed to provide the necessary dose.

The Involvement of Ascorbic Acid in Cancer Treatment

Vitamin C (VC), also known as ascorbic acid, plays a crucial role as a water-soluble nutrient within the human body, contributing to a variety of metabolic processes. Research findings suggest that increased doses of VC demonstrate potential anti-tumor capabilities. This review delves into the mechanisms of VC absorption and its implications for cancer management. Building upon these foundational insights, we explore modern delivery systems for VC, evaluating its use in diverse cancer treatment methods. These include starvation therapy, chemodynamic therapy (CDT), photothermal/photodynamic therapy (PTT/PDT), electrothermal therapy, immunotherapy, cellular reprogramming, chemotherapy, radiotherapy, and various combination therapies.

Hyperthermia combined with chemotherapy vs chemotherapy in patients with advanced pancreatic cancer: A multicenter retrospective observational comparative study

BACKGROUND

Several studies report the useful therapeutic results of regional hyperthermia in association with chemotherapy (CHT) and radiotherapy for the treatment of pancreatic cancer. Modulated electro-hyperthermia (mEHT) is a new hyperthermia technique that induces immunogenic death or apoptosis of pancreatic cancer cells in laboratory experiments and increases tumor response rate and survival in pancreatic cancer patients, offering beneficial therapeutic effects against this severe type of cancer.

AIM

To assess survival, tumor response and toxicity of mEHT alone or combined with CHT compared with CHT for the treatment of locally advanced or metastatic pancreatic cancer.

METHODS

This was a retrospective data collection on patients affected by locally advanced or metastatic pancreatic cancer (stage III and IV) performed in 9 Italian centers, members of International Clinical Hyperthermia Society-Italian Network. This study included 217 patients, 128 (59%) of them were treated with CHT (no-mEHT) and 89 (41%) patients received mEHT alone or in association with CHT. mEHT treatments were performed applying a power of 60-150 watts for 40-90 min, simultaneously or within 72 h of administration of CHT.

RESULTS

Median patients’ age was 67 years (range 31-92 years). mEHT group had a median overall survival greater than non-mEHT group (20 mo, range 1.6-24, vs 9 mo, range 0.4-56.25, P < 0.001). mEHT group showed a higher number of partial responses (45% vs 24%, P = 0.0018) and a lower number of progressions (4% vs 31%, P < 0.001) than the no-mEHT group, at the three months follow-up. Adverse events were observed as mild skin burns in 2.6% of mEHT sessions.

CONCLUSION

mEHT seems safe and has beneficial effects on survival and tumor response of stage III-IV pancreatic tumor treatment. Further randomized studies are warranted to confirm or not these results.

Heterogeneous Heat Absorption Is Complementary to Radiotherapy

Simple Summary

This review shows the advantages of heterogeneous heating of selected malignant cells in harmonic synergy with radiotherapy. The main clinical achievement of this complementary therapy is its extreme safety and minimal adverse effects. Combining the two methods opens a bright perspective, transforming the local radiotherapy to the antitumoral impact on the whole body, destroying the distant metastases by “teaching” the immune system about the overall danger of malignancy.

Abstract

(1) Background: Hyperthermia in oncology conventionally seeks the homogeneous heating of the tumor mass. The expected isothermal condition is the basis of the dose calculation in clinical practice. My objective is to study and apply a heterogenic temperature pattern during the heating process and show how it supports radiotherapy. (2) Methods: The targeted tissue’s natural electric and thermal heterogeneity is used for the selective heating of the cancer cells. The amplitude-modulated radiofrequency current focuses the energy absorption on the membrane rafts of the malignant cells. The energy partly “nonthermally” excites and partly heats the absorbing protein complexes. (3) Results: The excitation of the transmembrane proteins induces an extrinsic caspase-dependent apoptotic pathway, while the heat stress promotes the intrinsic caspase-dependent and independent apoptotic signals generated by mitochondria. The molecular changes synergize the method with radiotherapy and promote the abscopal effect. The mild average temperature (39–41 °C) intensifies the blood flow for promoting oxygenation in combination with radiotherapy. The preclinical experiences verify, and the clinical studies validate the method. (4) Conclusions: The heterogenic, molecular targeting has similarities with DNA strand-breaking in radiotherapy. The controlled energy absorption allows using a similar energy dose to radiotherapy (J/kg). The two therapies are synergistically combined.

Modulated Electro-Hyperthermia Supports the Effect of Gemcitabine Both in Sensitive and Resistant Pancreas Adenocarcinoma Cell Lines

The poor prognosis of pancreatic ductal adenocarcinoma (PDAC) is frequently associated to high treatment resistance. Gemcitabine (GEM) alone or in combination is the most used chemotherapy for unresecable PDACs. Here we studied whether modulated electro-hyperthermia (mEHT), a non-invasive complementary treatment, can support the effect of GEM on PDAC cells in vitro. The LD20 for the GEM-resistant Panc1 cells proved to be 200× higher than for the drug-sensitive Capan1. The mEHT alone caused significant apoptosis in Capan1 cultures as confirmed by the elevated SubG1 phase cell fraction and increased number of cleaved Caspase-3 positive cells 48 h after treatment, with an additive effect when GEM was used after hyperthermia. These were accompanied by reduced number of G1, S, and G2/M phase cells and elevated expression of the cyclin-dependent kinase inhibitor p21waf1 protein. In GEM-resistant Panc1 cells, an initial apoptosis was detected by flow cytometry 24 h after mEHT ± GEM treatment, which however diminished by 48 h at persistent number of cleaved Caspase-3 positive tumor cells. Though GEM monotherapy reduced the number of tumor progenitor colonies in Capan1 cell line, an additive colony inhibitory effect of mEHT was observed after mEHT + GEM treatment. The heat shock induced Hsp27 and Hsp70 proteins, which are known to sensitize PDAC cells to GEM were upregulated in both Capan1 and Panc1 cells 24 h after mEHT treatment. The level of E-Cadherin, a cell adhesion molecule, increased in Capan1 cells after mEHT + GEM treatment. In conclusion, in GEM-sensitive PDAC cells mEHT treatment alone induced cell death and cell cycle inhibition and improved GEM efficiency in combination, which effects were milder and short-term up to 24 h in the GEM-resistant Panc1 cells. Our data further support the inclusion of hyperthermia, in particular of mEHT, into the traditional oncotherapy regimens of PDAC.

Non-thermal membrane effects of electromagnetic fields and therapeutic applications in oncology

The temperature-independent effects of electromagnetic fields (EMF) have been controversial for decades. Here, we critically analyze the available literature on non-thermal effects of radiofrequency (RF) and microwave EMF. We present a literature review of preclinical and clinical data on non-thermal antiproliferative effects of various EMF applications, including conventional RF hyperthermia (HT, cRF-HT). Further, we suggest and evaluate plausible biophysical and electrophysiological models to decipher non-thermal antiproliferative membrane effects. Available preclinical and clinical data provide sufficient evidence for the existence of non-thermal antiproliferative effects of exposure to cRF-HT, and in particular, amplitude modulated (AM)-RF-HT. In our model, transmembrane ion channels function like RF rectifiers and low-pass filters. cRF-HT induces ion fluxes and AM-RF-HT additionally promotes membrane vibrations at specific resonance frequencies, which explains the non-thermal antiproliferative membrane effects via ion disequilibrium (especially of Ca²⁺) and/or resonances causing membrane depolarization, the opening of certain (especially Ca²⁺) channels, or even hole formation. AM-RF-HT may be tumor-specific owing to cancer-specific ion channels and because, with increasing malignancy, membrane elasticity parameters may differ from that in normal tissues. Published literature suggests that non-thermal antiproliferative effects of cRF-HT are likely to exist and could present a high potential to improve future treatments in oncology.

Clinical study of modulated electro-hyperthermia for advanced metastatic breast cancer

Modulated electro-hyperthermia (mEHT) is a new treatment modality developed to overcome the problems associated with traditional hyperthermia; mEHT uses a precise impedance-matched system and modulated radiofrequency current flow to malignant tumors. It selects the malignant cells based on their biophysical differences, due to their high metabolic rate, individual (autonomic) behavior and membrane status. The aim of the present study was to report the outcomes of mEHT in the treatment of advanced breast cancer. mEHT was examined in 10 patients with advanced metastatic breast cancer and recurrent disease, who were considered incurable by standard therapy protocols. Of the 10 patients, partial response was achieved in 3, disease stability in 3, and progressive disease in 4; however, their quality of life was improved based on their subjective reports. No adverse effects were observed in any of the 10 patients. The present study demonstrated the feasibility of mEHT as a possible therapy for advanced breast cancer cases when standard therapies fail. Moreover, mEHT had no side effects and may be combined with various treatments for long-term therapy.

Modulated Electro-Hyperthermia Facilitates NK-Cell Infiltration and Growth Arrest of Human A2058 Melanoma in a Xenograft Model

Modulated electro-hyperthermia (mEHT), induced by 13.56 MHz radiofrequency, has been demonstrated both in preclinical and clinical studies to efficiently induce tumor damage and complement other treatment modalities. Here, we used a mouse xenograft model of human melanoma (A2058) to test mEHT (~42°C) both alone and combined with NK-cell immunotherapy. A single 30 min shot of mEHT resulted in significant tumor damage due to induced stress, marked by high hsp70 expression followed by significant upregulation of cleaved/activated caspase-3 and p53. When mEHT was combined with either primary human NK cells or the IL-2 independent NK-92MI cell line injected subcutaneously, the accumulation of NK cells was observed at the mEHT pretreated melanoma nodules but not at the untreated controls. mEHT induced the upregulation of the chemoattractant CXCL11 and increased the expression of the matrix metalloproteinase MMP2 which could account for the NK-cell attraction into the treated melanoma. In conclusion, mEHT monotherapy of melanoma xenograft tumors induced irreversible heat and cell stress leading to caspase dependent apoptosis to be driven by p53. mEHT could support the intratumoral attraction of distantly injected NK-cells, contributed by CXCL11 and MMP2 upregulation, resulting in an additive tumor destruction and growth inhibition. Therefore, mEHT may offer itself as a good partner for immunotherapy.

Modulated Electro-Hyperthermia-Induced Tumor Damage Mechanisms Revealed in Cancer Models

The benefits of high-fever range hyperthermia have been utilized in medicine from the Ancient Greek culture to the present day. Amplitude-modulated electro-hyperthermia, induced by a 13.56 MHz radiofrequency current (mEHT, or Oncothermia), has been an emerging means of delivering loco-regional clinical hyperthermia as a complementary of radiation-, chemo-, and molecular targeted oncotherapy. This unique treatment exploits the metabolic shift in cancer, resulting in elevated oxidative glycolysis (Warburg effect), ion concentration, and electric conductivity. These promote the enrichment of electric fields and induce heat (controlled at 42 °C), as well as ion fluxes and disequilibrium through tumor cell membrane channels. By now, accumulating preclinical studies using in vitro and in vivo models of different cancer types have revealed details of the mechanism and molecular background of the oncoreductive effects of mEHT monotherapy. These include the induction of DNA double-strand breaks, irreversible heath and cell stress, and programmed cells death; the upregulation of molecular chaperones and damage (DAMP) signaling, which may contribute to a secondary immunogenic tumor cell death. In combination therapies, mEHT proved to be a good chemosensitizer through increasing drug uptake and tumor reductive effects, as well as a good radiosensitizer by downregulating hypoxia-related target genes. Recently, immune stimulation or intratumoral antigen-presenting dendritic cell injection have been able to extend the impact of local mEHT into a systemic "abscopal" effect. The complex network of pathways emerging from the published mEHT experiments has not been overviewed and arranged yet into a framework to reveal links between the pieces of the "puzzle". In this paper, we review the mEHT-related damage mechanisms published in tumor models, which may allow some geno-/phenotype treatment efficiency correlations to be exploited both in further research and for more rational clinical treatment planning when mEHT is involved in combination therapies.