Optimizing non-invasive radiofrequency hyperthermia treatment for improving drug delivery in 4T1 mouse breast cancer model

Recent strategies of carbon dot-based nanodrugs for enhanced emerging antitumor modalities

Nanomaterial-based cancer therapy has recently emerged as a new therapeutic modality with the advantages of minimal invasiveness and negligible normal tissue toxicity over traditional cancer treatments. However, the complex microenvironment and self-protective mechanisms of tumors have suppressed the therapeutic effect of emerging antitumor modalities, which seriously hindered the transformation of these modalities to clinical settings. Due to the excellent biocompatibility, unique physicochemical properties and easy surface modification, carbon dots, as promising nanomaterials in the biomedical field, can effectively improve the therapeutic effect of emerging antitumor modalities as multifunctional nanoplatforms. In this review, the mechanism and limitations of emerging therapeutic modalities are described. Further, the recent advances related to carbon dot-based nanoplatforms in overcoming the therapeutic barriers of various emerging therapies are systematically summarized. Finally, the prospects and potential obstacles for the clinical translation of carbon dot-based nanoplatforms in tumor therapy are also discussed. This review is expected to provide a reference for nanomaterial design and its development for the efficacy enhancement of emerging therapeutic modalities.

Preclinical Studies in Small Animals for Advanced Drug Delivery Using Hyperthermia and Intravital Microscopy

This paper presents three devices suitable for the preclinical application of hyperthermia via the simultaneous high-resolution imaging of intratumoral events. (Pre)clinical studies have confirmed that the tumor micro-environment is sensitive to the application of local mild hyperthermia. Therefore, heating is a promising adjuvant to aid the efficacy of radiotherapy or chemotherapy. More so, the application of mild hyperthermia is a useful stimulus for triggered drug release from heat-sensitive nanocarriers. The response of thermosensitive nanoparticles to hyperthermia and ensuing intratumoral kinetics are considerably complex in both space and time. To obtain better insight into intratumoral processes, longitudinal imaging (preferable in high spatial and temporal resolution) is highly informative. Our devices are based on (i) an external electric heating adaptor for the dorsal skinfold model, (ii) targeted radiofrequency application, and (iii) a microwave antenna for heating of internal tumors. These models, while of some technical complexity, significantly add to the understanding of effects of mild hyperthermia warranting implementation in research on hyperthermia.

External Basic Hyperthermia Devices for Preclinical Studies in Small Animals

Simple Summary

The application of mild hyperthermia can be beneficial for solid tumor treatment by induction of sublethal effects on a tissue- and cellular level. When designing a hyperthermia experiment, several factors should be taken into consideration. In this review, multiple elementary hyperthermia devices are described in detail to aid standardization of treatment design.

Abstract

Preclinical studies have shown that application of mild hyperthermia (40–43 °C) is a promising adjuvant to solid tumor treatment. To improve preclinical testing, enhance reproducibility, and allow comparison of the obtained results, it is crucial to have standardization of the available methods. Reproducibility of methods in and between research groups on the same techniques is crucial to have a better prediction of the clinical outcome and to improve new treatment strategies (for instance with heat-sensitive nanoparticles). Here we provide a preclinically oriented review on the use and applicability of basic hyperthermia systems available for solid tumor thermal treatment in small animals. The complexity of these techniques ranges from a simple, low-cost water bath approach, irradiation with light or lasers, to advanced ultrasound and capacitive heating devices.

Theoretical Analysis for Using Pulsed Heating Power in Magnetic Hyperthermia Therapy of Breast Cancer

In magnetic hyperthermia, magnetic nanoparticles (MNPs) are used to generate heat in an alternating magnetic field to destroy cancerous cells. This field can be continuous or pulsed. Although a large amount of research has been devoted to studying the efficiency and side effects of continuous fields, little attention has been paid to the use of pulsed fields. In this simulation study, Fourier's law and COMSOL software have been utilized to identify the heating power necessary for treating breast cancer under blood flow and metabolism to obtain the optimized condition among the pulsed powers for thermal ablation. The results showed that for small source diameters (not larger than 4 mm), pulsed powers with high duties were more effective than continuous power. Although by increasing the source domain the fraction of damage caused by continuous power reached the damage caused by the pulsed powers, it affected the healthy tissues more (at least two times greater) than the pulsed powers. Pulsed powers with high duty (0.8 and 0.9) showed the optimized condition and the results have been explained based on the Arrhenius equation. Utilizing the pulsed powers for breast cancer treatment can potentially be an efficient approach for treating breast tumors due to requiring lower heating power and minimizing side effects to the healthy tissues.

Resveratrol Induces Apoptosis and Attenuates Proliferation of MCF-7 Cells in Combination with Radiation and Hyperthermia

AIM

In the current in vitro study, we tried to examine the possible role of resveratrol as a sensitizer in combination with radiotherapy or hyperthermia.

BACKGROUND

Breast cancer is the most common malignancy for women and one of the most common worldwide. It has been suggested that using non-invasive radiotherapy alone cannot eliminate cancer cells. Hyperthermia, which is an adjuvant modality, induces cancer cell death mainly through apoptosis and necrosis. However, cancer cells can also develop resistance to this modality.

OBJECTIVE

The objective of this study was to determine possible potentiation of apoptosis when MCF-7 cells treated with resveratrol before hyperthermia or radiotherapy.

METHODS

MCF-7 cancer cells were treated with different doses of resveratrol to achieve IC50%. Afterwards, cells treated with the achieved concentration of resveratrol were exposed to radiation or hyperthermia. Proliferation, apoptosis and the expression of pro-apoptotic genes were evaluated using flow cytometry, MTT assay and real-time PCR. Results for each combination therapy were compared to radiotherapy or hyperthermia without resveratrol.

RESULTS

Both irradiation or hyperthermia could reduce the viability of MCF-7 cells. Furthermore, the regulation of Bax and caspase genes increased, while Bcl-2 gene expression reduced. Resveratrol potentiated the effects of radiation and hyperthermia on MCF-7 cells.

CONCLUSION

Results of this study suggest that resveratrol is able to induce the regulation of pro-apoptotic genes and attenuate the viability of MCF-7 cells. This may indicate the sensitizing effect of resveratrol in combination with both radiotherapy and hyperthermia.

Recent Progresses in Organic-Inorganic Nano Technological Platforms for Cancer Therapeutics

Nanotechnology offers promising tools in interdisciplinary research areas and getting an upsurge of interest in cancer therapeutics. Organic nanomaterials and inorganic nanomaterials bring revolutionary advancement in cancer eradication process. Oncology is achieving new heights under nano technological platform by expediting chemotherapy, radiotherapy, photo thermodynamic therapy, bio imaging and gene therapy. Various nanovectors have been developed for targeted therapy which acts as "Nano-bullets" for tumor cells selectively. Recently combinational therapies are catching more attention due to their enhanced effect leading towards the use of combined organicinorganic nano platforms. The current review covers organic, inorganic and their hybrid nanomaterials for various therapeutic action. The technological aspect of this review emphasizes on the use of inorganic-organic hybrids and combinational therapies for better results and also explores the future opportunities in this field.

Efficacy of Hyperthermia in Treatment of Recurrent Metastatic Breast Cancer After Long-Term Chemotherapy: A Report of 2 Cases

BACKGROUND Breast cancer has a long-term prognosis with various multimodality treatments. This report introduces the effectiveness of radiofrequency (RF) hyperthermia in the long-term treatment for recurrent/metastatic breast cancer. CASE REPORT In the first case, the patient had bone and liver metastases during the course of chemotherapy, hormone therapy, and radiotherapy for 27 years after curative resection of breast cancer. Finally, she received RF hyperthermia alone for liver metastasis and showed a decrease in tumor markers and reduction in liver metastasis on computed tomography (CT). In the second case, the patient underwent curative resection for multiple occurrences on the left side of the breast. She received postoperative chemotherapy combined with hormone therapy but had metachronous local recurrences. She continued hormone therapy after 2 local recurrence resections; unfortunately, she had bone, liver, and lung metastases and pleural dissemination. Eventually, the patient received RF hyperthermia combined with oral chemotherapy. Her tumor markers decreased, and CT showed disappearance of lung metastasis and improved pleural dissemination. Furthermore, the reduction of chemotherapy adverse events due to hyperthermia allowed the patient to continue chemotherapy and improved her quality of life. CONCLUSIONS We present 2 cases in which RF hyperthermia had a positive effect despite the presence of a recurrent tumor after various types of surgery, chemotherapy, and radiotherapy. This report suggests that the addition of RF hyperthermia to conventional multidisciplinary therapies may enhance the therapeutic effect of these treatments and improve the quality of life in patients with recurrent breast cancer.

Synergistic effects of pazopanib and hyperthermia against uterine leiomyosarcoma growth mediated by downregulation of histone acetyltransferase 1

Pazopanib-a multitargeted tyrosine kinase inhibitor with prominent antiangiogenic effects-has shown promise in the treatment of soft-tissue sarcomas. Hyperthermia has been also applied as an adjunctive treatment to chemotherapy for these malignancies. Here, we show that pazopanib and hyperthermia act synergistically in inhibiting uterine leiomyosarcoma (LMS) cell growth. Compared with either treatment alone, the combination of pazopanib and hyperthermia exerted the highest antitumor activity in a xenograft model. Mechanistically, we found that combined treatment with pazopanib and hyperthermia inhibited histone acetyltransferase 1 (HAT1) expression in LMS cells. The Clock element on the HAT1 promoter was critical for pazopanib- and hyperthermia-induced HAT1 downregulation. Inhibition of HAT1-either by pazopanib and hyperthermia or through HAT1 silencing-was mediated by suppression of Clock. Accordingly, Clock protein reconstitution rescued both HAT1 levels and HAT1-mediated histone acetylation. Immunohistochemistry revealed a higher expression of HAT1 in uterine LMS than in leiomyomas (p = 0.007), with high HAT1 expression levels being associated with poor clinical outcomes (p = 0.007). We conclude that pazopanib and hyperthermia exert synergistic effects against LMS growth by inhibiting HAT1. Further preclinical studies on HAT1 as a potential drug target in uterine LMS are warranted, especially in combination with hyperthermia. KEY MESSAGES: Pazopanib and hyperthermia inhibit the growth of leiomyosarcoma. Their combined use inhibits HAT1 expression in leiomyosarcoma cells. The promoter Clock element is required for HAT1 downregulation. HAT1 expression is higher in leiomyosarcoma than in leiomyomas. An increased HAT1 expression is associated with poor clinical outcomes.

Feasibility of removable balloon implant for simultaneous magnetic nanoparticle heating and HDR brachytherapy of brain tumor resection cavities

AIM

Hyperthermia (HT) has been shown to improve clinical response to radiation therapy (RT) for cancer. Synergism is dramatically enhanced if HT and RT are combined simultaneously, but appropriate technology to apply treatments together does not exist. This study investigates the feasibility of delivering HT with RT to a 5-10mm annular rim of at-risk tissue around a tumor resection cavity using a temporary thermobrachytherapy (TBT) balloon implant.

METHODS

A balloon catheter was designed to deliver radiation from High Dose Rate (HDR) brachytherapy concurrent with HT delivered by filling the balloon with magnetic nanoparticles (MNP) and immersing it in a radiofrequency magnetic field. Temperature distributions in brain around the TBT balloon were simulated with temperature dependent brain blood perfusion using numerical modeling. A magnetic induction system was constructed and used to produce rapid heating (>0.2°C/s) of MNP-filled balloons in brain tissue-equivalent phantoms by absorbing 0.5 W/ml from a 5.7 kA/m field at 133 kHz.

RESULTS

Simulated treatment plans demonstrate the ability to heat at-risk tissue around a brain tumor resection cavity between 40-48°C for 2-5cm diameter balloons. Experimental thermal dosimetry verifies the expected rapid and spherically symmetric heating of brain phantom around the MNP-filled balloon at a magnetic field strength that has proven safe in previous clinical studies.

CONCLUSIONS

These preclinical results demonstrate the feasibility of using a TBT balloon to deliver heat simultaneously with HDR brachytherapy to tumor bed around a brain tumor resection cavity, with significantly improved uniformity of heating over previous multi-catheter interstitial approaches. Considered along with results of previous clinical thermobrachytherapy trials, this new capability is expected to improve both survival and quality of life in patients with glioblastoma multiforme.

Imaging of Nanoparticle Distribution to Assess Treatments That Alter Delivery

Molecular imaging is a vital tool to non-invasively measure nanoparticle delivery to solid tumors. Despite the myriad of nanoparticles studied for cancer, successful applications of nanoparticles in humans is limited by inconsistent and ineffective delivery. Successful nanoparticle delivery in preclinical models is often attributed to enhanced permeability and retention (EPR)-a set of conditions that is heterogeneous and transient in patients. Thus, researchers are evaluating therapeutic strategies to modify nanoparticle delivery, particularly treatments which have demonstrated effects on EPR conditions. Imaging nanoparticle distribution provides a means to measure the effects of therapeutic intervention on nanoparticle delivery to solid tumors. This review focuses on the utility of imaging to measure treatment-induced changes in nanoparticle delivery to tumors and provides preclinical examples studying a broad range of therapeutic interventions.

Ultrasound Doppler as an Imaging Modality for Selection of Murine 4T1 Breast Tumors for Combination Radiofrequency Hyperthermia and Chemotherapy

Noninvasive radiofrequency-induced (RF) hyperthermia has been shown to increase the perfusion of chemotherapeutics and nanomaterials through cancer tissue in ectopic and orthotopic murine tumor models. Additionally, mild hyperthermia (37°C-45°C) has previously shown a synergistic anticancer effect when used with standard-of-care chemotherapeutics such as gemcitabine and Abraxane. However, RF hyperthermia treatment schedules remain unoptimized, and the mechanisms of action of hyperthermia and how they change when treating various tumor phenotypes are poorly understood. Therefore, pretreatment screening of tumor phenotypes to identify key tumors that are predicted to respond more favorably to hyperthermia will provide useful mechanistic data and may improve therapeutic outcomes. Herein, we identify key biophysical tumor characteristics in order to predict the outcome of combinational RF and chemotherapy treatment. We demonstrate that ultrasound imaging using Doppler mode can be utilized to predict the response of combinational RF and chemotherapeutic therapy in a murine 4T1 breast cancer model.

Chemotherapy and Radiofrequency-Induced Mild Hyperthermia Combined Treatment of Orthotopic Pancreatic Ductal Adenocarcinoma Xenografts

Patients with pancreatic ductal adenocarcinomas (PDAC) have one of the poorest survival rates of all cancers. The main reason for this is related to the unique tumor stroma and poor vascularization of PDAC. As a consequence, chemotherapeutic drugs, such as nab-paclitaxel and gemcitabine, cannot efficiently penetrate into the tumor tissue. Non-invasive radiofrequency (RF) mild hyperthermia treatment was proposed as a synergistic therapy to enhance drug uptake into the tumor by increasing tumor vascular inflow and perfusion, thus, increasing the effect of chemotherapy. RF-induced hyperthermia is a safer and non-invasive technique of tumor heating compared to conventional contact heating procedures. In this study, we investigated the short- and long-term effects (~20 days and 65 days, respectively) of combination chemotherapy and RF hyperthermia in an orthotopic PDAC model in mice. The benefit of nab-paclitaxel and gemcitabine treatment was confirmed in mice; however, the effect of treatment was statistically insignificant in comparison to saline treated mice during long-term observation. The benefit of RF was minimal in the short-term and completely insignificant during long-term observation.

Non-Invasive Radiofrequency Field Treatment of 4T1 Breast Tumors Induces T-cell Dependent Inflammatory Response

Previous work using non-invasive radiofrequency field treatment (RFT) in cancer has demonstrated its therapeutic potential as it can increase intratumoral blood perfusion, localization of intravenously delivered drugs, and promote a hyperthermic intratumoral state. Despite the well-known immunologic benefits that febrile hyperthermia can induce, an investigation of how RFT could modulate the intra-tumoral immune microenvironment had not been studied. Thus, using an established 4T1 breast cancer model in immune competent mice, we demonstrate that RFT induces a transient, localized, and T-cell dependent intratumoral inflammatory response. More specifically we show that multi- and singlet-dose RFT promote an increase in tumor volume in immune competent Balb/c mice, which does not occur in athymic nude models. Further leukocyte subset analysis at 24, 48, and 120 hours after a single RFT show a rapid increase in tumoral trafficking of CD4+ and CD8+ T-cells 24 hours post-treatment. Additional serum cytokine analysis reveals an increase in numerous pro-inflammatory cytokines and chemokines associated with enhanced T-cell trafficking. Overall, these data demonstrate that non-invasive RFT could be an effective immunomodulatory strategy in solid tumors, especially for enhancing the tumoral trafficking of lymphocytes, which is currently a major hindrance of numerous cancer immunotherapeutic strategies.