Local hyperthermia combined with radiotherapy and-/or chemotherapy: recent advances and promises for the future

Triple combination of heat, drug and radiation using alginate hydrogel co-loaded with gold nanoparticles and cisplatin for locally synergistic cancer therapy

Although multimodal cancer therapy has shown superior antitumor efficacy in comparison to individual therapy due to the potential generation of synergistic interactions among the treatments, its clinical usage is highly hampered by systemic dose-limiting toxicities. Herein, we developed a multi-responsive nanocomplex constructed from alginate hydrogel co-loaded with cisplatin and gold nanoparticles (AuNPs) (abbreviated as ACA) to combine chemotherapy, radiotherapy (RT) and photothermal therapy. The nanocomplex markedly improved the efficiency of drug delivery where ACA resulted in noticeably higher tumor growth inhibition than free cisplatin. The tumor treated with ACA showed an increased heating rate upon 532 nm laser irradiation, indicating the photothermal conversion ability of the nanocomplex. While RT alone resulted in slight tumor growth inhibition, thermo-chemo therapy, chemoradiation therapy and thermo-radio therapy using ACA dramatically slowed down the rate of tumor growth. Upon 532 nm laser and 6 MV X-ray, the nanocomplex could enable a trimodal thermo-chemo-radio therapy that yielded complete tumor regression with no evidence of relapse during the 90-days follow up period. The results of this study demonstrated that the incorporation of AuNPs and cisplatin into alginate hydrogel network can effectively combine chemotherapy, RT and photothermal therapy to achieve a locally synergistic cancer therapy.

Wideband Self-Grounded Bow-Tie Antenna for Thermal MR

The objective of this study was the design, implementation, evaluation and application of a compact wideband self-grounded bow-tie (SGBT) radiofrequency (RF) antenna building block that supports anatomical proton (¹ H) MRI, fluorine (¹⁹ F) MRI, MR thermometry and broadband thermal intervention integrated in a whole-body 7.0 T system. Design considerations and optimizations were conducted with numerical electromagnetic field (EMF) simulations to facilitate a broadband thermal intervention frequency of the RF antenna building block. RF transmission (B₁⁺ ) field efficiency and specific absorption rate (SAR) were obtained in a phantom, and the thigh of human voxel models (Ella, Duke) for ¹ H and ¹⁹ F MRI at 7.0 T. B₁⁺ efficiency simulations were validated with actual flip-angle imaging measurements. The feasibility of thermal intervention was examined by temperature simulations (f = 300, 400 and 500 MHz) in a phantom. The RF heating intervention (P_in = 100 W, t = 120 seconds) was validated experimentally using the proton resonance shift method and fiberoptic probes for temperature monitoring. The applicability of the SGBT RF antenna building block for in vivo ¹ H and ¹⁹ F MRI was demonstrated for the thigh and forearm of a healthy volunteer. The SGBT RF antenna building block facilitated ¹⁹ F and ¹ H MRI at 7.0 T as well as broadband thermal intervention (234-561 MHz). For the thigh of the human voxel models, a B₁⁺ efficiency ≥11.8 μT/√kW was achieved at a depth of 50 mm. Temperature simulations and heating experiments in a phantom demonstrated a temperature increase ΔT >7 K at a depth of 10 mm. The compact SGBT antenna building block provides technology for the design of integrated high-density RF applicators and for the study of the role of temperature in (patho-) physiological processes by adding a thermal intervention dimension to an MRI device (Thermal MR).

Differences of the Immune Phenotype of Breast Cancer Cells after Ex Vivo Hyperthermia by Warm-Water or Microwave Radiation in a Closed-Loop System Alone or in Combination with Radiotherapy

The treatment of breast cancer by radiotherapy can be complemented by hyperthermia. Little is known about how the immune phenotype of tumor cells is changed thereby, also in terms of a dependence on the heating method. We developed a sterile closed-loop system, using either a warm-water bath or a microwave at 2.45 GHz to examine the impact of ex vivo hyperthermia on cell death, the release of HSP70, and the expression of immune checkpoint molecules (ICMs) on MCF-7 and MDA-MB-231 breast cancer cells by multicolor flow cytometry and ELISA. Heating was performed between 39 and 44 °C. Numerical process simulations identified temperature distributions. Additionally, irradiation with 2 × 5 Gy or 5 × 2 Gy was applied. We observed a release of HSP70 after hyperthermia at all examined temperatures and independently of the heating method, but microwave heating was more effective in cell killing, and microwave heating with and without radiotherapy increased subsequent HSP70 concentrations. Adding hyperthermia to radiotherapy, dynamically or individually, affected the expression of the ICM PD-L1, PD-L2, HVEM, ICOS-L, CD137-L, OX40-L, CD27-L, and EGFR on breast cancer cells. Well-characterized pre-clinical heating systems are mandatory to screen the immune phenotype of tumor cells in clinically relevant settings to define immune matrices for therapy adaption.

Hyperthermia with photon radiotherapy is thermoradiobiologically analogous to neutrons for tumors without enhanced normal tissue toxicity

The depth dose profiles of photons mirror those of fast neutrons. However, in contrast to the high linear energy transfer (LET) characteristics of neutrons; photons exhibit low LET features. Hyperthermia (HT) inhibits the repair of radiation-induced DNA damage and is cytotoxic to the radioresistant hypoxic tumor cells. Thus, thermoradiobiologically, HT simulates high LET radiation with photons. At temperatures of 39-45 °C, the physiological vasodilation allows rapid heat dissipation from normal tissues. On the contrary, the chaotic and relatively rigid tumor vasculature results in heat retention leading to higher intratumoural temperatures. Consequently, the high LET attributes of HT with photon radiations are mostly limited to the confines of the heated tumor while the normothermic normal tissues would be irradiated with low LET photons. HT thereby augments photon therapy by conferring therapeutic advantages of high LET radiations to the tumors akin to neutrons, while the 'heat-sink' effect spares the normal tissues from thermal radiosensitization. Thus, photon thermoradiotherapy imparts radiobiological advantages selectively to tumors analogous to neutrons without exaggerating normal tissue morbidities. The later has been the major concern with clinical fast neutron beam therapy. Outcomes reported from several clinical trials in diverse tumor sites add testimony to the enhanced therapeutic efficacy of photon thermoradiotherapy.

Breath-hold MR-HIFU hyperthermia: phantom and in vivo feasibility

Background: The use of magnetic resonance imaging-guided high-intensity focused ultrasound (MR-HIFU) to deliver mild hyperthermia requires stable temperature mapping for long durations. This study evaluates the effects of respiratory motion on MR thermometry precision in pediatric subjects and determines the in vivo feasibility of circumventing breathing-related motion artifacts by delivering MR thermometry-controlled HIFU mild hyperthermia during repeated forced breath holds.Materials and methods: Clinical and preclinical studies were conducted. Clinical studies were conducted without breath-holds. In phantoms, breathing motion was simulated by moving an aluminum block towards the phantom along a sinusoidal trajectory using an MR-compatible motion platform. In vivo experiments were performed in ventilated pigs. MR thermometry accuracy and stability were evaluated.Results: Clinical data confirmed acceptable MR thermometry accuracy (0.12-0.44 °C) in extremity tumors, but not in the tumors in the chest/spine and pelvis. In phantom studies, MR thermometry accuracy and stability improved to 0.37 ± 0.08 and 0.55 ± 0.18 °C during simulated breath-holds. In vivo MR thermometry accuracy and stability in porcine back muscle improved to 0.64 ± 0.22 and 0.71 ± 0.25 °C during breath-holds. MR-HIFU hyperthermia delivered during intermittent forced breath holds over 10 min duration heated an 18-mm diameter target region above 41 °C for 10.0 ± 1.0 min, without significant overheating. For a 10-min mild hyperthermia treatment, an optimal treatment effect (TIR > 9 min) could be achieved when combining 36-60 s periods of forced apnea with 60-155.5 s free-breathing.Conclusion: MR-HIFU delivery during forced breath holds enables stable control of mild hyperthermia in targets adjacent to moving anatomical structures.

A moderate thermal dose is sufficient for effective free and TSL based thermochemotherapy

Hyperthermia, i.e. heating the tumor to a temperature of 40-43 °C is considered by many a valuable treatment to sensitize tumor cells to radiotherapy and chemotherapy. In recent randomized trials the great potential of adding hyperthermia to chemotherapy was demonstrated for treatment of high risk soft tissue sarcoma: +11.4% 5 yrs. overall survival (OS) and for ovarian cancer with peritoneal involvement nearly +12 months OS gain. As a result interest in combining chemotherapy with hyperthermia, i.e. thermochemotherapy, is growing. Extensive biological research has revealed that hyperthermia causes multiple effects, from direct cell kill to improved oxygenation, whereby each effect has a specific temperature range. Thermal sensitization of the tumor cell for chemotherapy occurs for many drugs at temperatures ranging from 40 to 42 °C with little additional increase of sensitization at higher temperatures. Increasing perfusion/oxygenation and increased extravasation are two other important hyperthermia induced mechanisms. The combination of free drug and hyperthermia has not been found to increase tumor drug concentration. Hence, enhanced effectiveness of free drug will depend on the thermal sensitization of the tumor cells for the applied drug. In contrast to free drugs, experimental animal studies combining hyperthermia and thermo-sensitive liposomal (TSL) drugs delivery have demonstrated to result in a substantial increase of the drug concentration in the tumor. For TSL based chemotherapy, hyperthermia is critical to both increase perfusion and extravasation as well as to trigger TSL drug release, whereby the temperature controlled induction of a local high drug concentration in a highly permeable vessel is driving the enhanced drug uptake in the tumor. Increased drug concentrations up to 26 times have been reported in rodents. Good control of the tissue temperature is required to keep temperatures below 43 °C to prevent vascular stasis. Further, careful timing of the drug application relative to the start of heating is required to benefit optimal from the combined treatment. From the available experimental data it follows that irrespective whether chemotherapy is applied as free drug or using a thermal sensitive liposomal carrier, the optimal thermal dose for thermochemotherapy should be 40-42 °C for 30-60 min, i.e. equivalent to a CEM43 of 1-15 min. Timing is critical: most free drug should be applied simultaneous with heating, whereas TSL drugs should be applied 20-30 min after the start of hyperthermia.

Recent technological advancements in radiofrequency- andmicrowave-mediated hyperthermia for enhancing drug delivery

Hyperthermia therapy is a potent enhancer of chemotherapy and radiotherapy. In particular, microwave (MW) and radiofrequency (RF) hyperthermia devices provide a variety of heating approaches that can treat most cancers regardless the size. This review introduces the physics of MW/RF hyperthermia, the current state-of-the-art systems for both localized and regional heating, and recent advancements in hyperthermia treatment guidance using real-time computational simulations and magnetic resonance thermometry. Clinical trials involving RF/MW hyperthermia as adjuvant for chemotherapy are also presented per anatomical site. These studies favor the use of adjuvant hyperthermia since it significantly improves curative and palliative clinical outcomes. The main challenge of hyperthermia is the distribution of state-of-the-art heating systems. Nevertheless, we anticipate that recent technology advances will expand the use of hyperthermia to chemotherapy centers for enhanced drug delivery. These new technologies hold great promise not only for (image-guided) perfusion modulation and sensitization for cytotoxic drugs, but also for local delivery of various compounds using thermosensitive liposomes.

Potentiation of the Abscopal Effect by Modulated Electro-Hyperthermia in Locally Advanced Cervical Cancer Patients

Background: A Phase III randomized controlled trial investigating the addition of modulated electro-hyperthermia (mEHT) to chemoradiotherapy for locally advanced cervical cancer patients is being conducted in South Africa (Human Research Ethics Committee approval: M1704133; ClincialTrials.gov ID: NCT03332069). Two hundred and ten participants were randomized and 202 participants were eligible for six month local disease control evaluation. Screening ¹⁸F-FDG PET/CT scans were conducted and repeated at six months post-treatment. Significant improvement in local control was reported in the mEHT group and complete metabolic resolution (CMR) of extra-pelvic disease was noted in some participants. We report on an analysis of the participants with CMR of disease inside and outside the radiation field.

Method: Participants were included in this analysis if nodes outside the treatment field (FDG-uptake SUV>2.5) were visualized on pre-treatment scans and if participants were evaluated by ¹⁸F-FDG PET/CT scans at six months post-treatment.

Results: One hundred and eight participants (mEHT: HIV-positive n = 25, HIV-negative n = 29; Control Group: HIV-positive n = 26, HIV-negative n = 28) were eligible for analysis. There was a higher CMR of all disease inside and outside the radiation field in the mEHT Group: n = 13 [24.1%] than the control group: n = 3 [5.6%] (Chi squared, Fisher's exact: p = 0.013) with no significant difference in the extra-pelvic response to treatment between the HIV-positive and -negative participants of each group.

Conclusion: The CMR of disease outside the radiation field at six months post-treatment provides evidence of an abscopal effect which was significantly associated with the addition of mEHT to treatment protocols. This finding is important as the combined synergistic use of radiotherapy with mEHT could broaden the scope of radiotherapy to include systemic disease.

Effective control of tumor growth through spatial and temporal control of theranostic sodium iodide symporter (NIS) gene expression using a heat-inducible gene promoter in engineered mesenchymal stem cells

Purpose: The tumor homing characteristics of mesenchymal stem cells (MSCs) make them attractive vehicles for the tumor-specific delivery of therapeutic agents, such as the sodium iodide symporter (NIS). NIS is a theranostic protein that allows non-invasive monitoring of the in vivo biodistribution of functional NIS expression by radioiodine imaging as well as the therapeutic application of ¹³¹I. To gain local and temporal control of transgene expression, and thereby improve tumor selectivity, we engineered MSCs to express the NIS gene under control of a heat-inducible HSP70B promoter (HSP70B-NIS-MSCs).

Experimental Design: NIS induction in heat-treated HSP70B-NIS-MSCs was verified by ¹²⁵I uptake assay, RT-PCR, Western blot and immunofluorescence staining. HSP70B-NIS-MSCs were then injected i.v. into mice carrying subcutaneous hepatocellular carcinoma HuH7 xenografts, and hyperthermia (1 h at 41°C) was locally applied to the tumor. 0 - 72 h later radioiodine uptake was assessed by ¹²³I-scintigraphy. The most effective uptake regime was then selected for ¹³¹I therapy.

Results: The HSP70B promoter showed low basal activity in vitro and was significantly induced in response to heat. In vivo, the highest tumoral iodine accumulation was seen 12 h after application of hyperthermia. HSP70B-NIS-MSC-mediated ¹³¹I therapy combined with hyperthermia resulted in a significantly reduced tumor growth with prolonged survival as compared to control groups.

Conclusions: The heat-inducible HSP70B promoter allows hyperthermia-induced spatial and temporal control of MSC-mediated theranostic NIS gene radiotherapy with efficient tumor-selective and temperature-dependent accumulation of radioiodine in heat-treated tumors.

Putative Abscopal Effect in Three Patients Treated by Combined Radiotherapy and Modulated Electrohyperthermia

Purpose: True abscopal responses from radiation therapy are extremely rare; the combination of immune checkpoint inhibitors with radiation therapy has led to more reports of the abscopal effect, but even in this setting, the genuine magnitude remains unknown and is still considered generally uncommon. We report the occurrence of what appears to be putative, durable abscopal tumor responses with associated auto-immune systemic reactions resulting from the combination of local radiotherapy (RT) and modulated electrohyperthermia (mEHT).

Materials and Methods: Data from advanced cancer patients treated palliatively with RT and mEHT between January and December 2017 were collected as part of a post-marketing safety monitoring program of mEHT therapy. We specified a minimum RT dose of 30 Gy and at least four mEHT treatments for reporting toxicities, which was the primary aim of the larger study.

Results: Thirty-three patients treated with RT and mEHT, both applied to the same lesion, were included. The median RT dose was 45.5 Gy in 20 fractions (fxs) and the median number of mEHT treatments was 12 (range, 4–20). Most patients had subsequent systemic therapy after one course of RT and mEHT. Three patients (9.1%) developed autoimmune toxicities. Case number 1 received RT and mEHT only; case number 2 had two cycles of concurrent low dose chemotherapy during RT; and case number 3 received concurrent immune checkpoint inhibitors. None of the three patients received any further systemic treatment due to obvious treatment-related autoimmune reactions which occurred rapidly after RT; one had autoimmune hepatitis, one had dermatitis herpetiformis and the third developed severe myasthenia gravis. Interestingly, what we surmise to be long-lasting abscopal responses outside the irradiated area, were noted in all three patients.

Conclusion: RT combined with mEHT could putatively result in enhancing immune responsiveness. These preliminary observational findings lead to the generation of a hypothesis that this combination induces both an in-situ, tumor-specific immune reaction and an anti-self-autoimmune reaction, in at least a small proportion of patients, and of those who experience the auto-immune response, tumor response is a concomitant finding. Mechanisms underlying this phenomenon need to be investigated further.

Radiosensitization by Hyperthermia: The Effects of Temperature, Sequence, and Time Interval in Cervical Cell Lines

Cervical cancers are almost exclusively caused by an infection with the human papillomavirus (HPV). When patients suffering from cervical cancer have contraindications for chemoradiotherapy, radiotherapy combined with hyperthermia is a good treatment option. Radiation-induced DNA breaks can be repaired by nonhomologous end-joining (NHEJ) or homologous recombination (HR). Hyperthermia can temporarily inactivate homologous recombination. Therefore, combining radiotherapy with hyperthermia can result in the persistence of more fatal radiation-induced DNA breaks. However, there is no consensus on the optimal sequence of radiotherapy and hyperthermia and the optimal time interval between these modalities. Moreover, the temperature of hyperthermia and HPV-type may also be important in radiosensitization by hyperthermia. In this study we thoroughly investigated the impact of different temperatures (37–42 °C), and the sequence of and time interval (0 up to 4 h) between ionizing radiation and hyperthermia on HPV16⁺: SiHa, Caski; HPV18⁺: HeLa, C4I; and HPV⁻: C33A, HT3 cervical cancer cell lines. Our results demonstrate that a short time interval between treatments caused more unrepaired DNA damages and more cell kill, especially at higher temperatures. Although hyperthermia before ionizing radiation may result in slightly more DNA damage, the sequence between hyperthermia and ionizing radiation yielded similar effects on cell survival.

Early results and volumetric analysis after spot-scanning proton therapy with concomitant hyperthermia in large inoperable sacral chordomas

OBJECTIVE

Large inoperable sacral chordomas show unsatisfactory local control rates even when treated with high dose proton therapy (PT). The aim of this study is assessing feasibility and reporting early results of patients treated with PT and concomitant hyperthermia (HT).

METHODS:

Patients had histologically proven unresectable sacral chordomas and received 70 Gy (relative biological effectiveness) in 2.5 Gy fractions with concomitant weekly HT. Toxicity was assessed according to CTCAE_v4. A volumetric tumor response analysis was performed.

RESULTS:

Five patients were treated with the combined approach. Median baseline tumor volume was 735 cc (range, 369-1142). All patients completed PT and received a median of 5 HT sessions (range, 2-6). Median follow-up was 18 months (range, 9-26). The volumetric analysis showed an objective response of all tumors (median shrinkage 46%; range, 9-72). All patients experienced acute Grade 2-3 local pain. One patient presented with a late Grade 3 iliac fracture.

CONCLUSION

Combining PT and HT in large inoperable sacral chordomas is feasible and causes acceptable toxicity. Volumetric analysis shows promising early results, warranting confirmation in the framework of a prospective trial.

ADVANCES IN KNOWLEDGE:

This is an encouraging first report of the feasibility and early results of concomitant HT and PT in treating inoperable sacral chordoma.

Thermal distribution, physiological effects and toxicities of extracorporeally induced whole-body hyperthermia in a pig model

Background

Extracorporeally induced whole‐body hyperthermia (eWBH) might be a beneficial treatment in cancer patients. Objectives of this pig study were to assess thermal distribution, (patho‐)physiological effects, and safety of eWBH with a new WBH device.

Methods

Fourteen healthy adult pigs were anesthetized, mechanically ventilated, and cannulated; 12 were included in the analysis. Blood was heated in 11 pigs (one pig served as control) using a WBH device (Vithèr Hyperthermia B.V.) containing two separate fluidic circuits and a heat exchanger. Temperature was monitored on nine different sites, including the brain. Core temperature (average of 4 deep probes) was elevated to 42°C for 2 hr.

Results

Elevation of core body temperature to 42°C took on average (± standard deviation) 38 ± 8 min. Initially observed temperature spikes diminished after lowering maximal blood temperature to 45°C. Hereafter, brain temperature spikes never exceeded 42.5°C, mean brain temperature was at highest 41.9°C during maintenance. WBH resulted in increased heart rates and decreased mean arterial pressures. The vast amounts of fluids required to counter hypotension tended to be smaller after corticosteroid administration. Hemodialysis was started in three animals (potassium increase prevention in two and hyperkalemia treatment in one). Severe rhabdomyolysis was observed in all pigs (including the control). All animals survived the procedure until planned euthanasia 1, 6, or 24 hr post procedure.

Conclusion

Fast induction of eWBH with homogenous thermal distribution is feasible in pigs using the Vithèr WBH device. Severe hemodynamic disturbances, rhabdomyolysis, and hyperkalemia were observed.

Injectable in Situ Forming Hydrogels of Thermosensitive Polypyrrole Nanoplatforms for Precisely Synergistic Photothermo-Chemotherapy

The combination of photothermal therapy (PTT) with chemotherapy has great potential to maximize the synergistic effect of thermo-induced chemosensitization and improve treatment performance. To achieve high drug-loading capacity as well as precise synchronization between the controllable release of chemotherapeutics and the duration of near-infrared PTT, in this work, a facile one-step method was first developed to fabricate a novel injectable in situ forming photothermal modulated hydrogel drug delivery platform (D-PPy@PNAs), in which a PNIPAM-based temperature-sensitive acidic triblock polymer [poly(acrylic acid-b-N-isopropylamide-b-acrylic acid (PNA)] was utilized as the stabilizing agent in the polymerization of polypyrrole (PPy). The in situ forming hydrogels showed a sensitive temperature-responsive sol-gel phase-transition behavior, as well as an excellent photothermal property. The strong interaction of ionic bonds together with π-π stacking interactions resulted in high doxorubicin (DOX) loading capacity and controlled/sustained drug release behavior. In addition, D-PPy@PNAs also displayed enhanced cellular uptake and promoted intratumoral penetration of DOX upon NIR laser irradiation. The synergistic photothermal therapy-chemotherapy of D-PPy@PNA hydrogels greatly improved the antitumor efficacy in vivo. Therefore, thermosensitive polypyrrole-based D-PPy@PNA hydrogels may be powerful drug delivery nanoplatforms for precisely synergistic photothermo-chemotherapy of tumors.

Graphene family nanomaterials for application in cancer combination photothermal therapy

Combining hyperthermia with other therapies holds a great potential for improving cancer treatment. In this approach, the increase in the body temperature can exert a therapeutic effect on cells and/or enhance the effectiveness of anticancer agents. However, the conventional methodologies available to induce hyperthermia cannot confine a high temperature increase to the tumor-site while maintaining healthy tissues unexposed and ensuring minimal invasiveness. To overcome these limitations, combination photothermal therapy (PTT) mediated by graphene family nanomaterials (GFN) has been showing promising results. Such is owed to the ability of GFN to accumulate at the tumor site and convert near infrared light into heat, enabling a hyperthermia with a high spatial-temporal resolution. Furthermore, GFN can also incorporate different therapeutic agents on their structure for delivery purposes to cancer cells. In this way, the combination PTT mediated by GFN can result in an improved therapeutic effect. In this review, the combination of GFN mediated PTT with chemo-, photodynamic-, gene-, radio-, and immuno-therapies is examined. Furthermore, the main parameters that influence these types of combination approaches are also analyzed, with emphasis on the photothermal potential of GFN and on the vascular and cellular effects produced by the temperature increase mediated by GFN.

Ablation of soft tissue tumours by long needle variable electrode-geometry electrochemotherapy: final report from a single-arm, single-centre phase-2 study

Standard electrochemotherapy (ECT) is effective in many tumour types but is confined to the treatment of small superficial lesions. Variable electrode-geometry ECT (VEG-ECT) may overcome these limitations by using long freely-placeable electrodes. Patients with bulky or deep-seated soft-tissue malignancies not amenable to resection participated in a single-arm phase-2 study (ISRCTN.11667954) and received a single course of VEG-ECT with intravenous bleomycin (15,000 IU/m²) and concomitant electric pulses applied through an adjustable electrode array. The primary outcome was radiologic complete response rate (CRR) per RECIST; secondary endpoints included feasibility, metabolic response, toxicity (CTCAE), local progression-free survival (LPFS) and patient perception (EQ-5D). During 2009–2014, we enrolled 30 patients with trunk/limb sarcomas, melanoma, Merkel-cell carcinoma, and colorectal/lung cancer. Median tumour size was 4.7 cm. Electrode probes were placed under US/TC guidance (28 and 2 patients, respectively). Median procedure duration was 80 minutes. Tumour coverage rate was 97% (29 of 30 patients). Perioperative side-effects were negligible; one patient experienced grade-3 ulceration and infection. One-month ¹⁸F-FDG-SUV decreased by 86%; CRR was 63% (95% CI 44–79%). Local control was durable in 24 of 30 patients (two-year LPFS, 62%). Patients reported an improvement in “usual activities”, “anxiety/depression”, and “overall health” scores. VEG-ECT demonstrated encouraging antitumour activity in soft-tissue malignancies; a single course of treatment produced high and durable responses, with low complications.

Conjugated polymer nano-systems for hyperthermia, imaging and drug delivery

Hyperthermia has shown tremendous therapeutic efficiency in the treatment of cancer due to its controllability, minimal invasiveness and limited side effects compared to the conventional treatment techniques like surgery, radiotherapy and chemotherapy. To improve the precision of hyperthermia specifically to a tumor location, near infra-red (NIR) light activatable inorganic metal nanoparticles have served as effective photothermal therapy materials, but toxicity and non-biodegradability have limited their clinical applications. Conjugated polymer nanoparticles have overcome these limitations and are emerging as superior photothermal materials owing to their excellent light harvesting nature, biocompatibility and tunable absorption properties. In this review we focus on the development of organic conjugated polymers (polyaniline, polypyrrole, polydopamine etc.) and their nanoparticles, which have broad NIR absorption. Such materials elicit photothermal effects upon NIR stimulation and may also serve as carriers for delivery of therapeutic and contrast agents for combined therapy. Subsequently, the emergence of donor-acceptor based semiconducting polymer nanoparticles with strong absorbance that is tunable across the NIR have been shown to eradicate tumors by either hyperthermia alone or combined with other therapies. The design of multifunctional polymer nanoparticles that absorb near- or mid- infrared light for heat generation, as well as their diagnostic abilities for precise biomedical applications are highlighted.

A combination drug delivery system employing thermosensitive liposomes for enhanced cell penetration and improved in vitro efficacy

Drug-loaded thermosensitive liposomes are investigated as drug delivery systems in combination with local mild hyperthermia therapy due to their capacity to release their cargo at a specific temperature range (40-42 °C). Additional benefit can be achieved by the development of such systems that combine two different anticancer drugs, have cell penetration properties and, when heated, release their drug payload in a controlled fashion. To this end, liposomes were developed incorporating at low concentration (5 mol%) a number of monoalkylether phosphatidylcholine lipids, encompassing the platelet activating factor, PAF, and its analogues that induce thermoresponsiveness and have anticancer biological activity. These thermoresponsive liposomes were efficiently (>90%) loaded with doxorubicin (DOX), and their thermal properties, stability and drug release were investigated both at 37 ^◦C and at elevated temperatures. In vitro studies of the most advantageous liposomal formulation containing the methylated PAF derivative (methyl-PAF, edelfosine), an established antitumor agent, were performed on human prostate cancer cell lines. This system exhibits controlled release of DOX at 40-42 °C, enhanced cell uptake due to the presence of methyl-PAF, and improved cell viability inhibition due to the combined action of both medications.

Development of Dual-Scale Fluorescence Endoscopy for In Vivo Bacteria Imaging in an Orthotopic Mouse Colon Tumor Model

Colorectal cancer is a representative cancer where early diagnosis and proper treatment monitoring are important. Recently, cancer treatment using bacteria has actively progressed and has been successfully monitored using fluorescence imaging techniques. However, because subcutaneous tumor models are limited in reflecting the actual colorectal cancer situation, new imaging approaches are needed to observe cancers growing in the colon. The fluorescence endoscopic approach is an optimal monitoring modality to evaluate the therapeutic response of bacteria in orthotopic colon cancer. In this study, we developed dual-scaled fluorescence endoscopy (DSFE) by combining wide-field fluorescence endoscopy (WFE) and confocal fluorescence endomicroscopy (CFEM) and demonstrated its usefulness for evaluating bacterial therapy. Firstly, the endoscopic probe of DSFE was developed by integrating the CFEM probe into the guide sheath of WFE. Secondly, colorectal cancer tumor growth and tumors infiltrating the fluorescent bacteria were successfully monitored at the multi-scale using DSFE. Finally, the bacterial distribution of the tumor and organs were imaged and quantitatively analyzed using CFEM. DSFE successfully exhibited fluorescent bacterial signals in an orthotopic mouse colon tumor model. Thus, it can be concluded that the DSFE system is a promising modality to monitor bacterial therapy in vivo.

Immune biological rationales for the design of combined radio- and immunotherapies

Cancer immunotherapies are promising treatments for many forms of cancer. Nevertheless, the response rates to, e.g., immune checkpoint inhibitors (ICI), are still in low double-digit percentage. This calls for further therapy optimization that should take into account combination of immunotherapies with classical tumor therapies such as radiotherapy. By designing multimodal approaches, immune modulatory properties of certain radiation schemes, additional immune modulation by immunotherapy with ICI and hyperthermia, as well as patient stratification based on genetic and immune constitutions have to be considered. In this context, both the tumor and its microenvironment including cells of the innate and adaptive immune system have to be viewed in synopsis. Knowledge of immune activation and immune suppression by radiation is the basis for well-elaborated addition of certain immunotherapies. In this review, the focus is set on additional immune stimulation by hyperthermia and restoration of an immune response by ICI. The impact of radiation dose and fractionation on immune modulation in multimodal settings has to be considered, as the dynamics of the immune response and the timing between radiotherapy and immunotherapy. Another big challenge is the patient stratification that should be based on matrices of biomarkers, taking into account genetics, proteomics, radiomics, and “immunomics”. One key aim is to turn immunological “cold” tumors into “hot” tumors, and to eliminate barriers of immune-suppressed or immune-excluded tumors. Comprehensive knowledge of immune alterations induced by radiation and immunotherapy when being applied together should be utilized for patient-adapted treatment planning and testing of innovative tumor therapies within clinical trials.

In situ formation, structural, mechanical and in vitro analysis of ZrO2/ZnFe2O4 composite with assorted composition ratios

The investigation underline the in situ formation of ZrO₂/ZnFe₂O₄ composites and the resultant structural, morphological, mechanical and magnetic properties. The characterization results ensured the crystallization of tetragonal ZrO₂ (t-ZrO₂) and ZnFe₂O₄ phases at 900 °C. Depending on Zn²⁺/Fe³⁺ content, the composite system revealed a gradual increment in the phase yield of ZnFe₂O₄. The significance of monoclinic ZrO₂ (m-ZrO₂) is also evident in all the systems at 900 °C; however, the incremental heat treatment to 1300 °C indicated its corresponding loss, thus indicating the reverse m- → t-ZrO₂ transition. The crystallization of ZnFe₂O₄ as a secondary phase in the t-ZrO₂ matrix is also affirmed from the morphological analysis. Mechanical studies accomplished good uniformity in all the investigated compositions despite the variation in the phase content of ZnFe₂O₄ in composite system. All the t-ZrO₂/ZnFe₂O₄ composites ensured strong ferrimagnetic features and moreover better biocompatibility and non-toxicity characteristics were displayed from in vitro tests.

Simulation-based design and characterization of a microwave applicator for MR-guided hyperthermia experimental studies in small animals

Purpose

The objective of this study was to design and characterize a 2.45 GHz microwave hyperthermia applicator for delivering hyperthermia in experimental small animals to 2 - 4 mm diameter targets located 1 - 3 mm from the skin surface, with minimal heating of the surrounding tissue, under 14.1 T MRI real-time monitoring and feedback control.

Materials and methods

An experimentally validated 3D computational model was employed to design and characterize a non-invasive directional water-cooled microwave hyperthermia applicator. We assessed the effects of: reflector geometry, monopole shape, cooling water temperature, and flow rate on spatial-temperature profiles. The system was integrated with real-time MR thermometry and feedback control to monitor and maintain temperature elevations in the range of 4 - 5 °C at 1 - 3 mm from the applicator surface. The quality of heating was quantified by determining the fraction of the target volume heated to the desired temperature, and the extent of heating in non-targeted regions.

Results

Model-predicted hyperthermic profiles were in good agreement with experimental measurements (Dice Similarity Coefficient of 0.95 - 0.99). Among the four considered criteria, a reflector aperture angle of 120 °, S-shaped monopole antenna with 0.6 mm displacement, and coolant flow rate of 150 ml/min were selected as the end result of the applicator design. The temperature of circulating water and input power were identified as free variables, allowing considerable flexibility in heating target sizes within varying distances from the applicator surface. 2 - 4 mm diameter targets positioned 1 - 3 mm from the applicator surface were heated to hyperthermic temperatures, with target coverage ratio ranging between 76 - 93 % and 11 - 26 % of non-targeted tissue heated.

Conclusion

We have designed an experimental platform for MR-guided hyperthermia, incorporating a microwave applicator integrated with temperature-based feedback control to heat deep-seated targets for experimental studies in small animals.

Molecular and biological rationale of hyperthermia as radio- and chemosensitizer

Mild hyperthermia, local heating of the tumour up to temperatures <43 °C, has been clinically applied for almost four decades and has been proven to substantially enhance the effectiveness of both radiotherapy and chemotherapy in treatment of primary and recurrent tumours. Clinical results and mechanisms of action are discussed in this review, including the molecular and biological rationale of hyperthermia as radio- and chemosensitizer as established in in vitro and in vivo experiments. Proven mechanisms include inhibition of different DNA repair processes, (in)direct reduction of the hypoxic tumour cell fraction, enhanced drug uptake, increased perfusion and oxygen levels. All mechanisms show different dose effect relationships and different optimal scheduling with radiotherapy and chemotherapy. Therefore, obtaining the ideal multi-modality treatment still requires elucidation of more detailed data on dose, sequence, duration, and possible synergisms between modalities. A multidisciplinary approach with different modalities including hyperthermia might further increase anti-tumour effects and diminish normal tissue damage.

A nano-based thermotherapy for cancer stem cell-targeted therapy

Cancer stem cells (CSCs) exhibit high resistance to conventional therapy and are responsible for cancer metastasis and tumor relapse.

Overview of the application of inorganic nanomaterials in cancer photothermal therapy

Cancer photothermal therapy (PTT) has captured the attention of researchers worldwide due to its localized and trigger-activated therapeutic effect.

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.

Large Malignant Fibrous Histiocytoma Treated with Hypofractionated Proton Beam Therapy and Local Hyperthermia

Purpose

Malignant fibrous histiocytoma (MFH) is one of the most common soft tissue sarcomas. The standard treatment is adequate surgical resection; in addition, radiation therapy plays a major role in perioperative treatment in most cases. Herein, we report the case of a patient with a large MFH who was successfully treated with combined proton beam therapy (PBT) and local hyperthermia (LH).

Case Presentation

A 60-year-old man presented with a 6×4-cm mass on his left thigh. Histopathology and immunohistochemistry indicated MFH, and he refused limb amputation. He received treatment with PBT at a dose at 72 GyE in 18 fractions. To cover the entire large target lesion, we used a patch-field protocol. He also concurrently received 7 courses of LH. The combination therapy achieved long-term local control without severe acute or late toxicity during the 7-year follow-up period.

Conclusions

This case suggests that the combination of PBT and LH may be an option as a limb-preserving treatment for large inoperable MFH in the extremities.

Review of the Clinical Evidences of Modulated Electro-Hyperthermia (mEHT) Method: An Update for the Practicing Oncologist

Background: Modulated electro-hyperthermia (mEHT) is a variation of the conventional hyperthermia which selectively targets the malignant cell membranes in order to heat the malignant tissue and sensitize the tissue to oncology treatments. Although widely applied, the formulation of guidelines for the use thereof is still in progress for many tumors. Aim: In this paper we review the literature on the effects of mEHT in cancer patients on local disease control and survival. Methodology: Our review on data presents the collected experience with capacitive hyperthermia treatments with the EHY-2000+ device (OncoTherm Ltd., Germany). A literature search was conducted in Pubmed and articles were grouped and discussed according to: trial type, animal studies, in vitro studies, and reviews. Search results from Conference Abstracts; Trial Registries; Thesis and Dissertations and the Oncothermia Journal were included in the discussions. Results: Modulated electro-hyperthermia is a safe form of hyperthermia which has shown to effectively sensitizes deep tumors, regardless of the thickness of the adipose layers. The technology has demonstrated equal benefits compared to other forms of hyperthermia for a variety of tumors. Given the effective heating ability to moderate temperatures, the improved tumor perfusion, and ability to increase drug absorption, mEHT is a safe and effective heating technology which can be easily applied to sensitize tumors which have demonstrated benefits with the addition of hyperthermia. Modulated electro-hyperthermia also appears to improve local control and survival rates and appears to induce an abscopal (systemic) response to ionizing radiation. Conclusion: Based on clinical studies, the method mEHT is a feasible hyperthermia technology for oncological applications. Concomitant utilization of mEHT is supported by the preclinical and clinical data.

Mild hyperthermia by MR-guided focused ultrasound in an ex vivo model of osteolytic bone tumour: optimization of the spatio-temporal control of the delivered temperature

BACKGROUND

Magnetic resonance guided focused ultrasound was suggested for the induction of deep localized hyperthermia adjuvant to radiation- or chemotherapy. In this study we are aiming to validate an experimental model for the induction of uniform temperature elevation in osteolytic bone tumours, using the natural acoustic window provided by the cortical breakthrough.

MATERIALS AND METHODS

Experiments were conducted on ex vivo lamb shank by mimicking osteolytic bone tumours. The cortical breakthrough was exploited to induce hyperthermia inside the medullar cavity by delivering acoustic energy from a phased array HIFU transducer. MR thermometry data was acquired intra-operatory using the proton resonance frequency shift (PRFS) method. Active temperature control was achieved via a closed-loop predictive controller set at 6 °C above the baseline. Several beam geometries with respect to the cortical breakthrough were investigated. Numerical simulations were used to further explain the observed phenomena. Thermal safety of bone heating was assessed by cross-correlating MR thermometry data with the measurements from a fluoroptic temperature sensor inserted in the cortical bone.

RESULTS

Numerical simulations and MR thermometry confirmed the feasibility of spatio-temporal uniform hyperthermia (± 0.5 °C) inside the medullar cavity using a fixed focal point sonication. This result was obtained by the combination of several factors: an optimal positioning of the focal spot in the plane of the cortical breakthrough, the direct absorption of the HIFU beam at the focal spot, the "acoustic oven effect" yielded by the beam interaction with the bone, and a predictive temperature controller. The fluoroptical sensor data revealed no heating risks for the bone and adjacent tissues and were in good agreement with the PRFS thermometry from measurable voxels adjacent to the periosteum.

CONCLUSION

To our knowledge, this is the first study demonstrating the feasibility of MR-guided focused ultrasound hyperthermia inside the medullar cavity of bones affected by osteolytic tumours. Our results are considered a promising step for combining adjuvant mild hyperthermia to external beam radiation therapy for sustained pain relief in patients with symptomatic bone metastases.

Field drift correction of proton resonance frequency shift temperature mapping with multichannel fast alternating nonselective free induction decay readouts

PURPOSE

To demonstrate that proton resonance frequency shift MR thermometry (PRFS-MRT) acquisition with nonselective free induction decay (FID), combined with coil sensitivity profiles, allows spatially resolved B₀ drift-corrected thermometry.

METHODS

Phantom experiments were performed at 1.5T and 3T. Acquisition of PRFS-MRT and FID were performed during MR-guided high-intensity focused ultrasound heating. The phase of the FIDs was used to estimate the change in angular frequency δω_drift per coil element. Two correction methods were investigated: (1) using the average δω_drift over all coil elements (0th-order) and (2) using coil sensitivity profiles for spatially resolved correction. Optical probes were used for independent temperature verification. In-vivo feasibility of the methods was evaluated in the leg of 1 healthy volunteer at 1.5T.

RESULTS

In 30 minutes, B₀ drift led to an apparent temperature change of up to -18°C and -98°C at 1.5T and 3T, respectively. In the sonicated area, both corrections had a median error of 0.19°C at 1.5T and -0.54°C at 3T. At 1.5T, the measured median error with respect to the optical probe was -1.28°C with the 0th-order correction and improved to 0.43°C with the spatially resolved correction. In vivo, without correction the spatiotemporal median of the apparent temperature was at -4.3°C and interquartile range (IQR) of 9.31°C. The 0th-order correction had a median of 0.75°C and IQR of 0.96°C. The spatially resolved method had the lowest median at 0.33°C and IQR of 0.80°C.

CONCLUSION

FID phase information from individual receive coil elements allows spatially resolved B₀ drift correction in PRFS-based MRT.

A Pilot Study of Radiotherapy and Local Hyperthermia in Elderly Patients With Muscle-Invasive Bladder Cancers Unfit for Definitive Surgery or Chemoradiotherapy

Purpose: To present the outcomes of a pilot study with hyperthermia (HT) and radiotherapy (RT) in elderly patients of muscle-invasive bladder cancers (MIBC) unfit for surgery or chemoradiotherapy (CTRT).

Methods: Sixteen elderly patients with unifocal or multifocal MIBCs received a total dose of 48 Gy/16 fractions/4 weeks or 50 Gy/20 fractions/4 weeks, respectively. HT with a radiofrequency HT unit was delivered once weekly for 60 min before RT and a mean temperature of 41.3°C was attained (maximum temperature 41.1–43.5°C). Local control was assessed using RECIST criteria at 3-monthly intervals by cystoscopy with or without biopsy.

Results: The median age, KPS and age-adjusted Charlson comorbidity index were 81 years, 70 and 5, respectively. At median follow-up of 18.5 months (range: 4–65), bladder preservation was 100% with satisfactory function. 11/16 patients (68.7%) had no local and/or distant failure, while isolated local, distant and combined local and distant failures were evident in 2, 2, and 1 patient, respectively. Two local failures were salvaged by TUR-BT resulting in a local control rate of 93.7%. The 5-year cause-specific (CS) local disease free survival (LDFS), disease free survival (DFS), and overall survival (OS) were 64.3, 51.6, and 67.5%, respectively while 5-year non-cause-specific (NCS)-LDFS, NCS-DFS, and NCS-OS were 26.5, 23.2, and 38%, respectively. None of the patients had acute or late grade 3/4 gastrointestinal or genitourinary toxicities.

Conclusions: The outcomes from this pilot study indicate that thermoradiotherapy is a feasible therapeutic modality in elderly MIBC patients unfit for surgery or CTRT. HTRT is well-tolerated, allows bladder preservation and function, achieves long-term satisfactory locoregional control and is devoid of significant treatment-related morbidity. This therapeutic approach deserves further evaluation in randomized studies.

Presence of Gold Nanoparticles in Cells Associated with the Cell-Killing Effect of Modulated Electro-Hyperthermia

The efficacy of gold nanoparticle (AuNP)-assisted radiofrequency (RF)-induced hyperthermia employing the Kanzius device remains controversial. Different from the Kanzius device, modulated electro-hyperthermia (mEHT) utilizes the capacitive-impedance coupled 13.56 MHz radiofrequency (RF) current and has been approved for clinical cancer treatment. In this study, we investigated the heating characteristics of spherical-, urchin-, and rod-like AuNPs of a similar 50 nm size upon exposure to a 13.56 MHz radiofrequency using the LabEHY-105CL, an in vivo mEHT device. We found that, regardless of the AuNPs' sphere-, urchin- or rod-like shape, purified gold nanoparticle solution would not promote heat generation. The temperature elevation during radiofrequency irradiation was solely attributed to the ionic background of the solution. The AuNPs present in the medium (≤25 ppm) showed no effect on selective cell killing of malignant cells, whereas the AuNPs incorporated in the cells diminished the cell selectivity as well as cell death and acted as protectors in mEHT cancer treatment. Our study suggested that (1) the temperature elevation induced by 50 nm AuNPs in the 13.56 MHz radiofrequency field was negligible and was shape-independent, and (2) the presence of AuNPs would alter the cell-killing effect of modulated electro-hyperthermia.

Confirmation of thermal dose as a predictor of local control in cervical carcinoma patients treated with state-of-the-art radiation therapy and hyperthermia

BACKGROUND

Addition of deep hyperthermia results in improved local control (LC) and overall survival (OS) compared to radiotherapy alone in patients with cervical carcinoma. Previously, we showed that the thermal dose of hyperthermia significantly correlates with LC and disease specific survival (DSS). Over the last decade, new radiation techniques were introduced resulting in improved LC.

AIM

To validate the effect of thermal dose in a more recent cohort of patients treated with modern radiotherapy techniques, including image guided brachytherapy (IGBT).

METHODS

We analyzed primary cervical carcinoma patients treated with a combination of radiotherapy and deep hyperthermia between 2005 and 2016 at our institute. Data on patient, tumor and treatment were collected including the thermal dose parameters TRISE and CEM43T90. Follow-up data on LC, disease free survival, DSS, OS as well as late toxicity data were collected. Data were analyzed using the Cox proportional hazard and Kaplan-Meier analyses.

RESULTS

227 patients were included. In multivariate analysis, histology, FIGO stage, lymphadenopathy, TRISE, CEM43T90 and IGBT had a significant effect on LC. In the patients treated with IGBT, the thermal dose parameter TRISE remained to have a significant effect on LC in univariate analysis.

CONCLUSIONS

The positive association between thermal dose and clinical outcome is replicated in an independent, recent cohort of cervical carcinoma patients. Importantly, in patients receiving IGBT, the effect of thermal dose on clinical outcome is still observed.

Patient-Specific Debye Parameters for Human Blood

This paper develops a patient-specific model for the Debye parameters of human blood based on hemoglobin content. Blood samples were collected from 176 patients visiting the University Hospital, with both permittivity measurements and standard hematological analysis performed on each blood draw. The complete blood count of each sample provided information on the hemoglobin concentration of each sample; in total there were 73 distinct hemoglobin concentrations reported. An iterative process was used to find patient-specific, based on hemoglobin content, Debye parameters. First, a two-stage genetic algorithm was used to solve for the parameters of a two-pole Debye model based on the mean-blood properties. Then, a modified two-pole Debye model incorporating hemoglobin information was developed, and those parameters were solved for using the same two-stage genetic algorithm. This paper presents the parameters for both the mean-blood model and the patient-specific model. The patient-specific model has a mean-fractional error across all 73 samples of 3.41% compared to 7.64% when using the mean-blood model to represent the entire population. This work demonstrates the range in the dielectric properties of human blood samples and highlights the need for incorporating patient-specific information when using the Debye parameters to model the dielectric properties of human blood.

Therapeutic bacteria to combat cancer; current advances, challenges, and opportunities

Successful treatment of cancer remains a challenge, due to the unique pathophysiology of solid tumors, and the predictable emergence of resistance. Traditional methods for cancer therapy including radiotherapy, chemotherapy, and immunotherapy all have their own limitations. A novel approach is bacteriotherapy, either used alone, or in combination with conventional methods, has shown a positive effect on regression of tumors and inhibition of metastasis. Bacteria-assisted tumor-targeted therapy used as therapeutic/gene/drug delivery vehicles has great promise in the treatment of tumors. The use of bacteria only, or in combination with conventional methods was found to be effective in some experimental models of cancer (tumor regression and increased survival rate). In this article, we reviewed the major advantages, challenges, and prospective directions for combinations of bacteria with conventional methods for tumor therapy.

Hyperthermia with radiotherapy reduces tumour alpha/beta: Insights from trials of thermoradiotherapy vs radiotherapy alone

PURPOSE

Hyperthermia inhibits the repair of irradiation-induced DNA damage and thereby could alter the α/β values of tumours. This study estimates the clinical α/β_HTRT values from clinical trials of thermoradiotherapy (HTRT) vs radiotherapy (RT) in recurrent breast (RcBC), head and neck (III/IV) (LAHNC) and cervix cancers (IIB-IVA) (LACC).

METHODS

Three recently published meta-analyses for HTRT vs RT in RcBC, LAHNC and LACC were evaluated for complete response (CR). Studies with specified RT dose (D), dose/fraction (d) and corresponding CRs were selected. Tumour biological effective dose (BED) for each study with RT (BED_RT) was computed assuming an α/β_RT of 10 Gy. As outcomes were favourable with HTRT, thermoradiobiological BED (BED_HTRT) was calculated as a product of BED_RT and %CR_HTRT/%CR_RT. The α/β_HTRT was estimated as Dd/(BED_HTRT - D).

RESULTS

12 trials with 864 patients were shortlisted - RcBC (3 studies, n = 259), LAHNC (5 studies, n = 338) and LACC (4 studies, n = 267). Overall risk difference of 0.28 favoured HTRT (p < 0.001). Mean BED_RT and BED_HTRT were 64.7 Gy (SD: ±15.5) and 109.5 Gy (SD: ±32.1) respectively and global α/β_HTRT was 2.25 Gy (SD: ±0.79). Mean α/β_HTRT for RcBC, LAHNC and LACC were 2.05 Gy, 1.74 Gy and 3.03 Gy respectively. On meta-regression, α/β_HTRT was the sole predictor for the corresponding risk differences of the studies (coefficient = -0.096; p = 0.03).

CONCLUSION

Thermoradiobiological effects on the repair of RT induced DNA damage results in reduction in α/β values of tumours. This should be considered to effectively optimize HTRT dose-fractionation schedules in the clinic.

Ultrasound Hyperthermia Technology for Radiosensitization

Hyperthermia therapy (HT) raises tissue temperature to 40-45°C for up to 60 min. Hyperthermia is one of the most potent sensitizers of radiation therapy (RT). Ultrasound-mediated HT for radiosensitization has been used clinically since the 1960s. Recently, magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU), which has been approved by the United States Food and Drug Administration for thermal ablation therapy, has been adapted for HT. With emerging clinical trials using MRgHIFU HT for radiosensitization, there is a pressing need to review the ultrasound HT technology. The objective of this review is to overview existing HT technology, summarize available ultrasound HT devices, evaluate clinical studies combining ultrasound HT with RT and discuss challenges and future directions.

Thermally-responsive Virus-like Particle for Targeted Delivery of Cancer Drug

Multifunctional nanocarriers displaying specific ligands and simultaneously response to stimuli offer great potentials for targeted and controlled drug delivery. Several synthetic thermally-responsive nanocarriers have been studied extensively for hyperthermia incorporated chemotherapy. However, no information is available on the application of virus-like particle (VLP) in thermally-controlled drug delivery systems. Here, we describe the development of a novel multifunctional nanovehicle based on the VLP of Macrobrachium rosenbergii nodavirus (MrNVLP). Folic acid (FA) was covalently conjugated to lysine residues located on the surface of MrNVLP, while doxorubicin (Dox) was loaded inside the VLP using an infusion method. This thermally-responsive nanovehicle, namely FA-MrNVLP-Dox, released Dox in a sustained manner and the rate of drug release increased in response to a hyperthermia temperature at 43 °C. The FA-MrNVLP-Dox enhanced the delivery of Dox to HT29 cancer cells expressing high level of folate receptor (FR) as compared to CCD841CoN normal cells and HepG2 cancer cells, which express low levels of FR. As a result, FA-MrNVLP-Dox increased the cytotoxicity of Dox on HT29 cells, and decreased the drug's cytotoxicity on CCD841CoN and HepG2 cells. This study demonstrated the potential of FA-MrNVLP-Dox as a thermally-responsive nanovehicle for targeted delivery of Dox to cancer cells rich in FR.

The Effect of the Time Interval Between Radiation and Hyperthermia on Clinical Outcome in 400 Locally Advanced Cervical Carcinoma Patients

Background: Addition of deep hyperthermia to radiotherapy results in improved local control (LC) and overall survival compared to radiotherapy alone in cervical carcinoma patients. Based on preclinical data, the time interval between radiotherapy, and hyperthermia is expected to influence treatment outcome. Clinical studies addressing the effect of time interval are sparse. The repercussions for clinical applications are substantial, as the time between radiotherapy and hyperthermia should be kept as short as possible. In this study, we therefore investigated the effect of the time interval between radiotherapy and hyperthermia on treatment outcome. Methods: We analyzed all primary cervical carcinoma patients treated between 1996 and 2016 with thermoradiotherapy at our institute. Data on patients, tumors and treatments were collected, including the thermal dose parameters TRISE and CEM43T90. Follow-up data on tumor status and survival as well as late toxicity were collected. Data was analyzed using Cox proportional hazards analysis and Kaplan Meier analysis. Results: 400 patients were included. Kaplan Meier and univariate Cox analysis showed no effect of the time interval (range 30-230 min) on any clinical outcome measure. Besides known prognostic factors, thermal dose parameters TRISE and CEM43T90 had a significant effect on LC. In multivariate analysis, the thermal dose parameter TRISE (HR 0.649; 95% CI 0.501-0.840) and the use of image guided brachytherapy (HR 0.432; 95% CI 0.214-0.972), but not the time interval, were significant predictors of LC and disease specific survival. Conclusions: The time interval between radiotherapy and hyperthermia, up to 4 h, has no effect on clinical outcome. These results are re-ensuring for our current practice of delivering hyperthermia within maximal 4 h after radiotherapy.