Ultrasound-mediated Hyperthermia Research Articles

Clinical trial protocol for PanDox: a phase I study of targeted chemotherapy delivery to non-resectable primary pancreatic tumours using thermosensitive liposomal doxorubicin (ThermoDox®) and focused ultrasound

BackgroundThe dense stroma of pancreatic ductal adenocarcinomas is a major barrier to drug delivery. To increase the local drug diffusion gradient, high doses of chemotherapeutic agent doxorubicin can be released from thermally-sensitive liposomes (ThermoDox®) using ultrasound-mediated hyperthermia at the tumour target. PanDox is designed as a Phase 1 single centre study to investigate enhancing drug delivery to adult patients with non-operable pancreatic ductal adenocarcinomas. The study compares a single cycle of either conventional doxorubicin alone or ThermoDox® with focused ultrasound-induced hyperthermia for targeted drug release.MethodsAdults with non-resectable pancreatic ductal adenocarcinoma are allocated to receive a single cycle of either doxorubicin alone (Arm A) or ThermoDox® with focused ultrasound-induced hyperthermia (Arm B), based on patient- and tumour-specific safety conditions. Participants in Arm B will undergo a general anaesthetic and pre-heating of the tumour by extra-corporal focused ultrasound (FUS). Rather than employing invasive thermometry, ultrasound parameters are derived from a patient-specific treatment planning model to reach the 41 °C target temperature for drug release. ThermoDox® is then concurrently infused with further ultrasound exposure. Tumour biopsies at the targeted site from all patients are analysed post-treatment using high performance liquid chromatography to quantify doxorubicin delivered to the tumour. The primary endpoint is defined as a statistically significant enhancement in concentration of total intra-tumoural doxorubicin, comparing samples from patients receiving liposomal drug with FUS to free drug alone. Participants are followed for 21 days post-treatment to assess secondary endpoints, including radiological assessment to measure changes in tumour activity by Positron Emission Tomography Response Criteria in Solid Tumours (PERCIST) criteria, adverse events and patient-reported symptoms.DiscussionThis early phase study builds on previous work targeting tumours in the liver to investigate whether enhancement of chemotherapy delivery using ultrasound-mediated hyperthermia can be translated to the stroma-dense environment of pancreatic ductal adenocarcinoma. If successful, it could herald a new approach towards managing these difficult-to-treat tumours.Trial registrationClinicalTrials.gov Identifier: NCT04852367. Registered 21st April 2022.EudraCT number: 2019–003950-10 (Registered 2019)Iras Project ID: 272253 (Registered 2019)Ethics Number: 20/EE/0284.

Target-Conformal Optimization-Based Actuator Placement for Ultrasound-Mediated Hyperthermia in Cancer Treatments

In hyperthermia for cancer treatments, tumors are heated to improve the outcome of radio-and chemotherapies. Using extracorporeal high-intensity focused ultrasound (HIFU) transducers, the heating can be applied noninvasively, accurately, and with high acoustic power. The heating location can be changed by electronic beam steering, within the transducer’s small local heating range, and by mechanically repositioning the transducer, which effectively shifts the local range to enable the treatment of larger tumors. An important problem is the selection of the sonication points, i.e., the discrete locations reachable by electronic beam steering, and the admissible mechanical transducer positions, which must be performed prior to treatment, and can be seen as an actuator selection problem. Clearly, the selected sonication points and transducer positions have a major impact on the achievable tumor temperatures, and their number is directly related to the controller’s complexity and, thereby, real-time feasibility. To address this challenging problem, this brief presents a target-conformal optimization-based actuator placement procedure, designed to assist the clinician in enabling maximum treatment quality using only a limited number of sonication points and transducer positions. The method is computationally tractable, and takes into account the specific tumor geometry and tissue properties.

Effects of human tissue acoustic properties, abdominal wall shape, and respiratory motion on ultrasound-mediated hyperthermia for targeted drug delivery to pancreatic tumors

Background PanDox is a Phase-1 trial of chemotherapeutic drug delivery to pancreatic tumors using ultrasound-mediated hyperthermia to release doxorubicin from thermally sensitive liposomes. This report describes trial-related hyperthermia simulations featuring: (i) new ultrasonic properties of human pancreatic tissues, (ii) abdomen deflections imposed by a water balloon, and (iii) respiration-driven organ motion. Methods Pancreas heating simulations were carried out using three patient body models. Pancreas acoustic properties were varied between values found in the literature and those determined from our human tissue study. Acoustic beam distortion was assessed with and without balloon-induced abdomen deformation. Target heating was assessed for static, normal respiratory, and jet-ventilation-controlled pancreas motion. Results Human pancreatic tumor attenuation is 63% of the literature values, so that pancreas treatments require commensurately higher input intensity to achieve adequate hyperthermia. Abdominal wall deformation decreased the peak field pressure by as much as 3.5 dB and refracted the focal spot by as much as 4.5 mm. These effects were thermally counteracted by sidelobe power deposition, so the net impact on achieving mild hyperthermia was small. Respiratory motion during moving beam hyperthermia produced localized regions overheated by more than 8.0 °C above the 4.0 °C volumetric goal. The use of jet ventilation reduced this excess to 0.7 °C and yielded temperature field uniformity that was nearly identical to having no respiratory motion. Conclusion Realistic modeling of the ultrasonic propagation environment is critical to achieving adequate mild hyperthermia without the use of real time thermometry for targeted drug delivery in pancreatic cancer patients.

Development of thermosensitive resiquimod-loaded liposomes for enhanced cancer immunotherapy

Resiquimod (R848) is a toll-like receptor 7 and 8 (TLR7/8) agonist with potent antitumor and immunostimulatory activity. However, systemic delivery of R848 is poorly tolerated because of its poor solubility in water and systemic immune activation. In order to address these limitations, we developed an intravenously-injectable formulation with R848 using thermosensitive liposomes (TSLs) as a delivery vehicle. R848 was remotely loaded into TSLs composed of DPPC: DSPC: DSPE-PEG2K (85:10:5, mol%) with 100 mM FeSO4 as the trapping agent inside. The final R848 to lipid ratio of the optimized R848-loaded TSLs (R848-TSLs) was 0.09 (w/w), 10-fold higher than the previously-reported values. R848-TSLs released 80% of R848 within 5 min at 42 °C. These TSLs were then combined with αPD-1, an immune checkpoint inhibitor, and ultrasound-mediated hyperthermia in a neu deletion (NDL) mouse mammary carcinoma model (Her2+, ER/PR negative). Combined with αPD-1, local injection of R848-TSLs showed superior efficacy with complete NDL tumor regression in both treated and abscopal sites achieved in 8 of 11 tumor bearing mice over 100 days. Immunohistochemistry confirmed enhanced CD8+ T cell infiltration and accumulation by R848-TSLs. Systemic delivery of R848-TSLs, combined with local hyperthermia and αPD-1, inhibited tumor growth and extended median survival from 28 days (non-treatment control) to 94 days. Upon re-challenge with reinjection of tumor cells, none of the previously cured mice developed tumors, as compared with 100% of age-matched control mice. The dose of R848 (10 μg for intra-tumoral injection or 6 mg/kg for intravenous injection delivered up to 4 times) was well-tolerated without weight loss or organ hypertrophy. In summary, we developed R848-TSLs that can be administered locally or systematically, resulting in tumor regression and enhanced survival when combined with αPD-1 in mouse models of breast cancer.

Focused Ultrasound-Mediated Hyperthermia in Vitro: An Experimental Arrangement for Treating Cells under Tissue-Mimicking Conditions

An experimental arrangement that allows in vitro exposure of cells to focused ultrasound-mediated hyperthermia (43°C–55°C) in a tissue-mimicking phantom with biological, acoustic and thermal properties comparable to those of human soft tissue is described. Cells were embedded in a compressed collagen gel, which was sandwiched between 6-mm-thick slices of biocompatible, acoustically absorbing and thermally tissue mimicking poly(vinyl alcohol) cryo-gel. To illustrate the system's potential, cells were exposed using a 1.66-MHz focused ultrasound beam (spatial-peak temporal-average intensities (ISPTA) = 900–1400 W/cm2) that traced out a circular trajectory (5–8 mm in diameter). Real-time temperature monitoring allowed cells to be exposed reproducibly to a pre-determined thermal dose. An experimental planning tool that estimates the thermal dose distribution throughout the sample and allows spatial correlation with cell position has been developed. Treatment response was evaluated qualitatively using microscopy and cell viability testing. This experimental arrangement has significant potential for future, biologically relevant, in vitro focused ultrasound-mediated hyperthermia studies.

Abstract 2171: Activatable nanodelivery of high payload gemcitabine augments therapeutic efficacy in murine breast and pancreatic cancer models

Abstract Gemcitabine (Gem) is the standard of treatment for metastatic pancreatic ductal adenocarcinoma (PDAC) and an effective anticancer drug for various solid tumors. However, clinical application of Gem chemotherapy is hampered by suboptimal delivery of the drug, mainly due to short circulation time and poor penetration of drug into the hypo-vascularized and dense fibrous stroma of PDAC. Here, we present a novel method to improve both loading and stability of Gem in temperature-sensitive liposomes (TSL). TSL have the potential to be locally activated by exposing tumor to ultrasound-mediated hyperthermia (USH) triggering release of large amounts of free drug in the tumor vasculature, which can then rapidly penetrate into the heated tumor. Gem was passively loaded into TSL composed of DPPC:DSPC:DSPE-PEG2k (80:15:5) in the presence of copper(II) gluconate and triethanolamine at final 0.12 mg-drug/mg-lipid. Formation of a CuGem complex improved drug loading and stability and reduced systemic toxicity. Mice with bilateral invasive neu deletion (NDL) tumors (4-5 mm) were treated with an i.v. administration of CuGem-TSL at 10 mg Gem/kg body weight. USH was employed to trigger the release of drug; one tumor in the bilateral tumor model was insonified with a peak ultrasound pressure of 1.1 MPa at a frequency of 1.5 MHz at 43°C for 5 min prior to and 30 min post drug injection with a variable duty cycle. We found that copper(II) gluconate possesses superior potential to solubilize Gem up to 150 mg/mL and augments passive drug loading. Upon loading Gem, formation of a complex with copper further improved drug loading and stability within TSL. By optimizing the lipid composition of the liposomal shell, we achieved high loading content of Gem at up to 12% by weight in TSL (CuGem-TSL), 4-fold greater than previously reported. Cryo electron microscopy confirmed the presence of liquid crystalline structures within CuGem-TSL, which was not observed in the absence of copper (Gem-TSL). The resulting high-content CuGem-TSL displayed a rapid release of Gem (80%) within 5 min at 42°C with only 25% release over 30 min at 37°C in the presence of serum. In vitro CuGem-TSL demonstrated equivalent toxicity to free Gem against both murine breast cancer and pancreatic cancer. One hour following intravenous administration, 75% of Gem was effectively retained in circulating TSL, whereas no drug was detected in mouse plasma with free drug administration. Three repeated administrations of CuGem-TSL combined with USH over a two-week treatment course suppressed tumor growth in NDL, model of murine breast cancer, with limited toxicity, enhancing survival when compared to treatment with free Gem alone. Additionally, in a more aggressive tumor model of murine pancreatic cancer (KrasLSL-G12D/+; Trp53LSL-R172H/+; Pdx-Cre, mT4 tumor source), CuGem-TSL with USH induced cell death and regions of apoptosis and necrosis. Citation Format: Samantha T. Tucci, Azadeh Kheirolomoom, Elizabeth S. Ingham, Lisa M. Mahakian, Sarah M. Tam, Josquin Foiret, Neil E. Hubbard, Alexander D. Borowsky, Mo Baikoghli, R. Holland Cheng, Katherine W. Ferrara. Activatable nanodelivery of high payload gemcitabine augments therapeutic efficacy in murine breast and pancreatic cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2171.

Combining activatable nanodelivery with immunotherapy in a murine breast cancer model

A successful chemotherapy-immunotherapy solid-tumor protocol should accomplish the following goals: debulk large tumors, release tumor antigen for cross-presentation and cross-priming, release cancer-suppressive cytokines and enhance anti-tumor immune cell populations. Thermally-activated drug delivery particles have the potential to synergize with immunotherapeutics to accomplish these goals; activation can release chemotherapy within bulky solid tumors and can enhance response when combined with immunotherapy. We set out to determine whether a single protocol, combining locally-activated chemotherapy and agonist immunotherapy, could accomplish these goals and yield a potentially translational therapy. For effective delivery of free doxorubicin to tumors with minimal toxicity, we stabilized doxorubicin with copper in temperature-sensitive liposomes that rapidly release free drug in the vasculature of cancer lesions upon exposure to ultrasound-mediated hyperthermia. We found that in vitro exposure of tumor cells to hyperthermia and doxorubicin resulted in immunogenic cell death and the local release of type I interferons across murine cancer cell lines. Following intravenous injection, local activation of the liposomes within a single tumor released doxorubicin and enhanced cross-presentation of a model antigen at distant tumor sites. While a variety of protocols achieved a complete response in >50% of treated mice, the complete response rate was greatest (90%) when 1 week of immunotherapy priming preceded a single activatable chemotherapeutic administration. While repeated chemotherapeutic delivery reduced local viable tumor, the complete response rate and a subset of tumor immune cells were also reduced. Taken together, the results suggest that activatable chemotherapy can enhance adjuvant immunotherapy; however, in a murine model the systemic adaptive immune response was greatest with a single administration of chemotherapy.

Clinical trial protocol for TARDOX: a phase I study to investigate the feasibility of targeted release of lyso-thermosensitive liposomal doxorubicin (ThermoDox\xae) using focused ultrasound in patients with liver tumours

BackgroundTARDOX is a Phase I single center study of ultrasound triggered targeted drug delivery in adult oncology patients with incurable liver tumours. This proof of concept study is designed to demonstrate the safety and feasibility of targeted drug release and enhanced delivery of doxorubicin from thermally sensitive liposomes (ThermoDox®) triggered by mild hyperthermia induced by focused ultrasound in liver tumours. A key feature of the study is the direct quantification of the doxorubicin concentration before and after ultrasound exposure from tumour biopsies, using high performance liquid chromatography (HPLC).Methods/DesignThe study is conducted in two parts: Part 1 includes minimally-invasive thermometry via a thermistor or thermocouple implanted through the biopsy co-axial needle core, to confirm ultrasound-mediated hyperthermia, whilst Part 2 is carried out without invasive thermometry, to more closely mimic the ultimately intended clinical implementation of the technique. Whilst under a general anaesthetic, adult patients with incurable confirmed hepatic primary or secondary (metastatic) tumours receive a single cycle of ThermoDox®, immediately followed by ultrasound-mediated hyperthermia in a single target liver tumour. For each patient in Part 1, the HPLC-derived total doxorubicin concentration in the ultrasound-treated tumour is directly compared to the concentration before ultrasound exposure in that same tumour. For each patient in Part 2, as the tumour biopsy taken before ultrasound exposure is not available, the mean of those Part 1 tumour concentrations is used as the comparator. Success of the study requires at least a two-fold increase in the total intratumoural doxorubicin concentration, or final concentrations over 10 μg/g, in at least 50% of all patients receiving the drug, where tissue samples are evaluable by HPLC. Secondary outcome measures evaluate safety and feasibility of the intervention. Radiological response in the target tumour and control liver tumours are analysed as a tertiary outcome measure, in addition to plasma pharmacokinetics, fluorescence microscopy and immunohistochemistry of the biopsy samples.DiscussionIf this early phase study can demonstrate that ultrasound-mediated hyperthermia can effectively enhance the delivery and penetration of chemotherapy agents intratumorally, it could enable application of the technique to enhance therapeutic outcomes across a broad range of drug classes to treat solid tumours.Trial registrationClinicalTrials.gov Identifier: NCT02181075, Edura-CT Identifier: 2014-000514-61.Ethics Number: 14/NE/0124.

Abstract B14: A novel strategy for the treatment of melanoma

Abstract Introduction: Approximately 76,000 individuals are diagnosed with melanoma, and about 9,000 die as a result of the disease each year in the United States. Even though there are many options for standard treatment of melanoma such as surgical resection, radiotherapy, intraregional therapy with sclerosing agents, isolated limb perfusion, and immunotherapy, the mortality rate is still high. The high mortality reflects a lack of effective therapeutic methods for the treatment of melanoma. The purpose of this study is to develop an effective therapeutic approach for the treatment of melanoma, using mild/moderate (less-than 41oC) hyperthermia (HT) to actively modulate the delivery of the FDA approved anticancer drug nab-paclitaxel (human serum albumin (HSA) based paclitaxel-nanoparticle) to tumors. Physiologically, HSA serves as a natural carrier to deliver nutrients, including itself as an amino acid source to cells with metabolic and/or reproductive needs by binding to its receptor albondin on the cell surfaces. We and other investigators have reported that the rate of cellular metabolism increases as temperature rises to the mild/moderate temperature range of 38oC to 41oC, implying that heat increase cellular uptake of HSA to meet the demands of the higher metabolic rate. In the clinic, nab-paclitaxel has demonstrated preferential uptake in tumors with good solubility, stability and longer circulation time with limited toxicity. In this study, we used HT to deliver nab-paclitaxel to melanoma xenograft in athymic mice. Materials and Methods: Human melanoma A375 and G361 cells were purchased from ATCC (American Type Culture Collection) and maintained in a growth medium of Dulbecco's Modified Eagle's Medium (A375) and McCoy's 5A medium (G361) supplemented with 10% human serum, 100 units/ml penicillin and 100 μg/ml streptomycin. Both melanoma cells were adapted to human serum containing medium by maintaining them in the medium for at least 6 months. Human fibroblast GM05399 cells were obtained from Coriell Cell Repositories (Coriell Institute, Camden, NJ). Near infrared (NIR) dye (IRDye 800CW) Protein Labeling Kits were purchased from Li-Cor Inc. Nude mice, 4 or 5-weeks-old, were bought from the National Cancer Institute at Frederick, MD. Immunofluorescence staining and flow cytometry methods were applied to measure HSA in tumor cells in vitro after heat treatment. To observe the biodistribution of nab-paclitaxel in vivo, we labeled nab-paclitaxel with NIR dye using an IRDye 800CW Protein Labeling Kit following the manufacturer's instructions. The integrity of the nab-paclitaxel after a single freezing and thawing cycle, and nab-paclitaxel-NIR dye conjugates were measured using Dynamic Light Scattering (DLS). Biodistribution and kinetic changes of the nab-paclitaxel-NIR dye conjugates were examined and monitored after injection of the conjugates and heat treatment with the Pearl Imager in melanoma xenograft carrying animals. Results: (1). HSA accumulated in melanoma cells after heating at 41oC for as little as 0.5 hour; there was no increase in the amount of HSA in human normal fibroblasts after the same heat treatment. (2). Integrity of the nab-paclitaxel was not interrupted after a single freezing and thawing cycle, and by the labeling procedures with fluorescent dye. (3). Most interestingly nab-paclitaxel and its NIR dye conjugates are stable after heating at 41oC for 1 hr. (4). Mild/moderate HT actively modulated the delivery of nab-paclitaxel-NIR dye conjugates to tumors, accumulated and retained nab-paclitaxel-NIR conjugates in the tumor for at least 72 hrs. Conclusion and Future Studies: HT has been previously used to improve blood circulation and increase cell membrane permeability for antitumor chemical delivery to tumors in the clinic. In this study, the accumulation of nab-paclitaxel in heated tumor cells appears to be receptor-mediated. Because of size constraints, nab-paclitaxel could not passively diffuse into tumor cells, even cells permeabilized by heat treatment. Therefore, our preliminary results have demonstrated that mild/moderate hyperthermia can actively facilitate delivery of nab-paclitaxel to tumors in vitro and in vivo. HT promoted retention of nab-paclitaxel-NIR conjugates in tumor xenograft for a prolonged period of time as compared to controls (without heat treatment). A study is currently underway to evaluate the therapeutic efficacy of HT combined with nab-paclitaxel in the treatment of melanoma in vivo. A study to assess whether whole body hyperthermia can modulate delivery of nab-paclitaxel to metastatic tumors is being considered. Magnetic Resonance-guided High Intensity Focused Ultrasound mediated HT in combination with nab-paclitaxel may be an effective approach for the treatment of melanoma. Citation Format: Mai Xu, Albert C. Lockhart, Robert J. Myerson, Imran Zoberi, Gerald P. Linette, Andrea Wang-Gillam. A novel strategy for the treatment of melanoma. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Melanoma: From Biology to Therapy; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(14 Suppl):Abstract nr B14.

Complete regression of local cancer using temperature-sensitive liposomes combined with ultrasound-mediated hyperthermia

The development of treatment protocols that result in a complete response to chemotherapy has been hampered by free drug toxicity and the low bioavailability of nano-formulated drugs. Here, we explore the application of temperature-sensitive liposomes that have been formulated to enhance stability in circulation. We formed a pH-sensitive complex between doxorubicin (Dox) and copper (CuDox) in the core of lysolipid-containing temperature-sensitive liposomes (LTSLs). The complex remains associated at neutral pH but dissociates to free Dox in lower pH environments. The resulting CuDox-LTSLs were injected intravenously into a syngeneic murine breast cancer model (6mg Dox/kg body weight) and intravascular release of the drug was triggered by ultrasound. The entire tumor was insonified for 5min prior to drug administration and 20min post drug injection. A single-dose administration of CuDox-LTSLs combined with insonation suppressed tumor growth. Moreover, after twice per week treatment over a period of 28days, a complete response was achieved in which the NDL tumor cells and the tumor interstitium could no longer be detected. All mice treated with ultrasound combined with CuDox-LTSLs survived, and tumor was undetectable 8months post treatment. Iron and copper-laden macrophages were observed at early time points following treatment with this temperature sensitive formulation. Systemic toxicity indicators, such as cardiac hypertrophy, leukopenia, and weight and hair loss were not detected with CuDox-LTSLs after the 28-day therapy.

Abstract 2155: Achieving complete response to locoregional disease without toxicity using temperature-sensitive liposomes and ultrasound-mediated hyperthermia.

Abstract By stabilizing doxorubicin within temperature-sensitive liposomes and repeating delivery twice per week for four weeks, extended survival and complete response were obtained in syngeneic murine breast tumors. Further, with the stabilized formulation, cardiac toxicity and leukopenia were not detected. Liposomes composed of DPPC:MPPC:DSPE-PEG2k, 86:10:4 were prepared in the presence of copper(II) gluconate and triethanolamine and extruded with 100 nm membrane filters. Cu-liposomes were loaded with Dox at 0.2 mg-drug/mg-lipid with 100% loading. We studied the efficacy of CuDox liposomes (CuDox-LTSLs) using the highly invasive neu deletion (NDL) tumor. Treatment began when the tumor diameter reached 4 mm. The fluorescence of circulating doxorubicin in blood was quenched after the digestion of liposomes with Triton X-100, indicating that the circulating drug remained associated with copper. Dox fluorescence was restored upon reducing the pH using a citrate-saline buffer. Over the 28 days of the study, CuDox-LTSLs were administrated intravenously two times per week at a therapeutic level of 6 mg-drug/kg-body weight. The entire tumor was insonified with a peak ultrasound pressure of 1.1 MPa at a frequency of 1.5 MHz at 42°C for 5 min prior to and 20 min post drug injection. A total of 30 mice were studied, including groups spanning drug treatment with ultrasound, ultrasound, drug treatment and no treatment. Although a single dose administration of CuDox-LTSLs combined with insonation of the entire tumor suppressed the tumor growth, complete response was achieved only upon repeated treatment over a period of 28 days. At 30 days after the last administered dose, none of the mice from the other groups survive; however, 100% of mice treated with ultrasound combined with CuDox-LTSLs survive and the remaining tumor is undetectable. In conclusion, repeated treatment of stabilized temperature sensitive doxorubicin liposomes is highly effective in the treatment of aggressive murine tumors. Acknowledgement: NIHR01CA134659 and NIHR01CA103828 Citation Format: Azadeh Kheirolomoom, Chun-Yen Lai, Sarah M. TAM, Lisa M. Even, Elizabeth S. Ingham, Brett Z. Fite, Katherine D. Watson, Katherine W. Ferrara. Achieving complete response to locoregional disease without toxicity using temperature-sensitive liposomes and ultrasound-mediated hyperthermia. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2155. doi:10.1158/1538-7445.AM2013-2155

Multimodal Cancer Treatment: Real Time Monitoring, Optimization, and Synergistic Effects

The primary objective of this analysis is to provide the theoretical framework for a novel multimodal cancer treatment system emphasizing the use of ultrasound as a synergistic drug release mechanism, real time monitoring by MRI of hyperthermic, pO2, and ultrasound induced released effects. The aim is to provide a cure for the 20% of cancer victims who will die of complications from local solid tumors. Adjuvant therapy usually refers to surgery preceding or following chemotherapy and/or ionizing radiation treatment to decrease the risk of recurrence, but the absolute benefit for survival obtained with adjuvant therapy compared to control is only approximately 6%. Tumor hypoxia represents a primary therapeutic concern, besides multi-drug resistance (MDR), because it can reduce the effectiveness of drugs and radiotherapy; well-oxygenated cells require one-third the dose of hypoxic cells to achieve a given level of cell killing. The era of systemic and indiscriminate chemotherapeutic drug delivery into both healthy and pathologic tissues is near an end. Targeted drug delivery using nanoparticles is emerging as the new vehicle, either as a single treatment option, as part of adjuvant procedures or as a component of a multimodal cancer treatment system. There are more than 100 nanosized liposomes or particles, and conjugated anticancer agents in various stages of preclinical and clinical development. Active targeting can be achieved by site-specific delivery or site-specific triggering. Ultrasound can be utilized as both a site triggering and synergistic mechanism in drug release. The process can be monitored using MRI by a physical process called cavitation. An analysis of low frequency ultrasound exposure in combination with liposomally encapsulated doxorubicin (Caelyx) on Balb/c nude mice inoculated with a WiDr (human colon cancer) tumor cell line provided tumor growth inhibition of 30-40%. Mild hyperthermia causes mean intra-tumor pO2 to increase by 25% and enhances tumor radiosensitization. Hyperthermia causes the extravasation of liposome nanoparticles in deep tumor regions. Ionizing radiation improves the distribution and uptake of drugs. Liposomally encapsulated drugs and ultrasound mediated hyperthermia have been proven to circumvent MDR effects. Hyperthermic effects and pO2 monitoring of bodily fluid have been performed by MRI. It is hypothesized that increased vascularization and subsequent increase in pO2 levels to hypoxic regions, and monitoring of drug release through cavitation, can facilitate optimized real time concomitant or sequential treatments of drug therapy, hyperthermia, ionizing radiation, etc., before or after surgery. An improved therapeutic index with the use of the outlined system seems probable.

Regulation of transgene expression in muscles by ultrasound-mediated hyperthermia

Heat-sensitive transgene expression systems have been proposed recently for use in gene therapy to enable both spatial and temporal control of the gene activity. The transgene was put under the control of HSP-related promoters and could be turned on by external heat treatment. While the 'heat activation' phenomenon of the HSP-related promoters in vitro had been well documented, the detailed time response and temporal regulation profile in vivo were not fully understood. We reported here the regulation of transgene luciferase expression in vivo in muscles using a custom-built ultrasound-mediated hyperthermia instrument. The effects of different heating parameters and treatment regimens were evaluated. Optimal activation of gene expression was found at 39 degrees C. Significant tissue damage was observed at 41 degrees C and above, which directly correlated with the greatly reduced gene expression. The gene constructs remained stable and silent in muscle cells, and could be turned on at a later time without losing much activity. Repeated activation was also possible, but required heat treatment at a higher temperature to overcome thermotolerance.