Thermal and mechanical high-intensity focused ultrasound: perspectives on tumor ablation, immune effects and combination strategies

Sensitize Tumor Immunotherapy: Immunogenic Cell Death Inducing Nanosystems

Low immunogenicity of tumors poses a challenge in the development of effective tumor immunotherapy. However, emerging evidence suggests that certain therapeutic approaches, such as chemotherapy, radiotherapy, and phototherapy, can induce varying degrees of immunogenic cell death (ICD). This ICD phenomenon leads to the release of tumor antigens and the maturation of dendritic cells (DCs), thereby enhancing tumor immunogenicity and promoting immune responses. However, the use of a single conventional ICD inducer often fails to achieve in situ tumor ablation and establish long-term anti-tumor immune responses. Furthermore, the induction of ICD induction varies among different approaches, and the distribution of the therapeutic agent within the body influences the level of ICD and the occurrence of toxic side effects. To address these challenges and further boost tumor immunity, researchers have explored nanosystems as inducers of ICD in combination with tumor immunotherapy. This review examines the mechanisms of ICD and different induction methods, with a specific focus on the relationship between ICD and tumor immunity. The aim is to explore the research advancements utilizing various nanomaterials to enhance the body's anti-tumor effects by inducing ICD. This paper aims to contribute to the development and clinical application of nanomaterial-based ICD inducers in the field of cancer immunotherapy by providing important theoretical guidance and practical references.

Ultrasound-induced immune responses in tumors: A systematic review and meta-analysis

Ultrasound is widely used in the diagnosis and therapy of cancer. Tumors can be treated by thermal or mechanical tissue ablation. Furthermore, tumors can be manipulated by hyperthermia, sonodynamic therapy and sonoporation, e.g., by increasing tumor perfusion or the permeability of biological barriers to enhance drug delivery. These treatments induce various immune responses in tumors. However, conflicting data and high heterogeneity between experimental settings make it difficult to generalize the effects of ultrasound on tumor immunity. Therefore, we performed a systematic review to answer the question: "Does ultrasound alter the immune reaction of peripheral solid tumors in humans and animals compared to control conditions without ultrasound?" A systematic literature search was performed in PubMed, EMBASE, and Web of Science and 24,401 potentially relevant publications were identified. Of these, 96 publications were eligible for inclusion in the systematic review. Experiments were performed in humans, rats, and mice and focused on different tumor types, primarily breast and melanoma. We collected data on thermal and non-thermal ultrasound settings, the use of sono-sensitizers or sono-enhancers, and anti-tumor therapies. Six meta-analyses were performed to quantify the effect of ultrasound on tumor infiltration by T cells (cytotoxic, helper, and regulatory T cells) and on blood cytokines (interleukin-6, interferon-γ, tumor necrosis factor-α). We provide robust scientific evidence that ultrasound alters T cell infiltration into tumors and increases blood cytokine concentrations. Furthermore, we identified significant differences in immune cell infiltration based on tumor type, ultrasound settings, and mouse age. Stronger effects were observed using hyperthermia in combination with sono-sensitizers and in young mice. The latter may impair the translational impact of study results as most cancer patients are older. Thus, our results may help refining ultrasound parameters to enhance anti-tumor immune responses for therapeutic use and to minimize immune effects in diagnostic applications.

Ultrasound-Controlled Prodrug Activation: Emerging Strategies in Polymer Mechanochemistry and Sonodynamic Therapy

Ultrasound has gained prominence in biomedical applications due to its noninvasive nature and ability to penetrate deep tissue with spatial and temporal resolution. The burgeoning field of ultrasound-responsive prodrug systems exploits the mechanical and chemical effects of ultrasonication for the controlled activation of prodrugs. In polymer mechanochemistry, materials scientists exploit the sonomechanical effect of acoustic cavitation to mechanochemically activate force-sensitive prodrugs. On the other hand, researchers in the field of sonodynamic therapy adopt fundamentally distinct methodologies, utilizing the sonochemical effect (e.g., generation of reactive oxygen species) of ultrasound in the presence of sonosensitizers to induce chemical transformations that activate prodrugs. This cross-disciplinary review comprehensively examines these two divergent yet interrelated approaches, both of which originated from acoustic cavitation. It highlights molecular and materials design strategies and potential applications in diverse therapeutic contexts, from chemotherapy to immunotherapy and gene therapy methods, and discusses future directions in this rapidly advancing domain.

Intratumoural immunotherapy plus focal thermal ablation for localized prostate cancer

Major advances have been made in the use of immunotherapy for the treatment of solid tumours, including the use of intratumourally injected immunotherapy instead of systemically delivered immunotherapy. The success of immunotherapy in prostate cancer treatment has been limited to specific populations with advanced disease, which is thought to be a result of prostate cancer being an immunologically 'cold' cancer. Accordingly, combining intratumoural immunotherapy with other treatments that would increase the immunological heat of prostate cancer is of interest. Thermal ablation therapy is currently one of the main strategies used for the treatment of localized prostate cancer and it causes immunological activation against prostate tissue. The use of intratumoural immunotherapy as an adjunct to thermal ablation offers the potential to elicit a systemic and lasting adaptive immune response to cancer-specific antigens, leading to a synergistic effect of combination therapy. The combination of thermal ablation and immunotherapy is currently in the early stages of investigation for the treatment of multiple solid tumour types, and the potential for this combination therapy to also offer benefit to prostate cancer patients is exciting.

New insights into mechanisms and interventions of locoregional therapies for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is responsible for a significant number of cancer-related deaths worldwide and its incidence is increasing. Locoregional treatments, which are precision procedures guided by imaging to specifically target liver tumors, play a critical role in the management of a substantial portion of HCC cases. These therapies have become an essential element of the HCC treatment landscape, with transarterial chemoembolization (TACE) being the treatment of choice for patients with intermediate to advanced stages of the disease. Other locoregional therapies, like radiofrequency ablation, are highly effective for small, early-stage HCC. Nevertheless, the advent of targeted immunotherapy has challenged these established treatments. Tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs) have shown remarkable efficacy in clinical settings. However, their specific uses and the development of resistance in subsequent treatments have led clinicians to reevaluate the future direction of HCC therapy. This review concentrates on the distinct features of both systemic and novel locoregional therapies. We investigate their effects on the tumor microenvironment at the molecular level and discuss how targeted immunotherapy can be effectively integrated with locoregional therapies. We also examine research findings from retrospective studies and randomized controlled trials on various combined treatment regimens, assessing their validity to determine the future evolution of locoregional therapies within the framework of personalized, comprehensive treatment.

Responsive Supramolecular Polymers for Diagnosis and Treatment

Stimuli-responsive supramolecular polymers are ordered nanosized materials that are held together by non-covalent interactions (hydrogen-bonding, metal-ligand coordination, π-stacking and, host-guest interactions) and can reversibly undergo self-assembly. Their non-covalent nature endows supramolecular polymers with the ability to respond to external stimuli (temperature, light, ultrasound, electric/magnetic field) or environmental changes (temperature, pH, redox potential, enzyme activity), making them attractive candidates for a variety of biomedical applications. To date, supramolecular research has largely evolved in the development of smart water-soluble self-assemblies with the aim of mimicking the biological function of natural supramolecular systems. Indeed, there is a wide variety of synthetic biomaterials formulated with responsiveness to control and trigger, or not to trigger, aqueous self-assembly. The design of responsive supramolecular polymers ranges from the use of hydrophobic cores (i.e., benzene-1,3,5-tricarboxamide) to the introduction of macrocyclic hosts (i.e., cyclodextrins). In this review, we summarize the most relevant advances achieved in the design of stimuli-responsive supramolecular systems used to control transport and release of both diagnosis agents and therapeutic drugs in order to prevent, diagnose, and treat human diseases.

Experimental and Computational Analysis of High-Intensity Focused Ultrasound Thermal Ablation in Breast Cancer Cells: Monolayers vs. Spheroids

High-intensity focused ultrasound (HIFU) is a non-invasive therapeutic modality that uses precise acoustic energy to ablate cancerous tissues through coagulative necrosis. In this context, we investigate the efficacy of HIFU ablation in two distinct cellular configurations, namely 2D monolayers and 3D spheroids of epithelial breast cancer cell lines (MDA-MB 231 and MCF7). The primary objective is to compare the response of these two in vitro models to HIFU while measuring their ablation percentages and temperature elevation levels. HIFU was systematically applied to the cell cultures, varying ultrasound intensity and duty cycle during different sonication sessions. The results indicate that the degree of ablation is highly influenced by the duty cycle, with higher duty cycles resulting in greater ablation percentages, while sonication duration has a minimal impact. Numerical simulations validate experimental observations, highlighting a significant disparity in the response of 2D monolayers and 3D spheroids to HIFU treatment. Specifically, tumor spheroids require lower temperature elevations for effective ablation, and their ablation percentage significantly increases with elevated duty cycles. This study contributes to a comprehensive understanding of acoustic energy conversion within the biological system during HIFU treatment for 2D versus 3D ablation targets, holding potential implications for refining and personalizing breast cancer therapeutic strategies.

Tumor suppression effect of ultrasound-sensitive nanoparticles with focused ultrasound in a pancreas cancer xenograft model

BACKGROUND

We investigated the tumor suppression effect of an ultrasound-sensitive doxorubicin-loaded liposome-based nanoparticle, IMP301, to enhance the synergistic effect with focused ultrasound (FUS) in an animal model of pancreatic cancer.

METHODS

Thirty nude mice with xenografts of PANC-1 human pancreatic cancer cells were randomly and prospectively allocated to 6 different groups (5 per group) each for Study-1 (dose-response test) and Study-2 (synergistic effect test). Study-1 consisted of control, gemcitabine, Doxil with FUS, and three different doses of IMP301 (2, 4, 6 mg/kg) with FUS groups. Study-2 consisted of control, FUS only, gemcitabine, Doxil with FUS, and IMP301 (4 mg/kg) with or without FUS groups. Differences in tumor volume and growth rate were evaluated by one-way ANOVA and Student-Newman-Keuls test.

RESULTS

In Study-1, 4 mg/kg or greater IMP301 with FUS groups showed lower tumor growth rates of 14 ± 4 mm3/day (mean ± standard deviation) or less, compared to the control, gemcitabine, and Doxil with FUS groups with rates exceeding 28 ± 5 (p < 0.050). The addition of FUS in Study-2 decreased the tumor growth rate in the IMP301-treated groups from 36 ± 17 to 9 ± 6, which was lower than the control, FUS only, gemcitabine, and Doxil with FUS groups (p < 0.050).

CONCLUSIONS

IMP301 combined with FUS exhibited higher tumor growth suppression compared to the use of a conventional drug alone or the combination with FUS. The present study showed the potential of IMP301 to enhance the synergistic effect with FUS for the treatment of pancreatic cancer.

RELEVANCE STATEMENT

This article aims to evaluate the synergistic effect of FUS and ultrasound-responsive liposomal drug in tumor growth suppression by using xenograft mouse model of pancreatic ductal adenocarcinoma. FUS-induced ultrasound-sensitive drug release may be a potential noninvasive repeatable treatment option for patients with locally advanced or unresectable pancreatic cancer.

KEY POINTS

• Modification of conventional drugs combined with FUS would maximize tumor suppression. • IMP301 with FUS had higher tumor suppression effect compared to conventional chemotherapy. • This image-guided drug delivery would enhance therapeutic effects of systemic chemotherapy.

Microwave ablation enhances the systemic immune response in patients with lung cancer

Microwave ablation (MWA) is a key alternative therapy to conventional surgery for the treatment of lung cancer. In addition to eliminating local tumors, MWA may promote antitumor immunological responses, such as abscopal effects in distant lesions. However, the intensity of MWA is limited and the underlying mechanisms are not well-defined. The present study assessed the impact of MWA on immune cell subsets and cytokines in patients with lung cancer. A total of 45 patients with lung cancer who underwent percutaneous lung tumor MWA were enrolled. Peripheral blood samples were collected before and 24 h after MWA and changes in immune cell subsets [lymphocytes, CD3+, CD4+ and CD8+ T cells, B cells and natural killer (NK) cells] and serum cytokine levels (IL-1β, IL-2, IL-4-6, IL-8, IL-10, IL-12p70, IL-17A and F, IL-22, TNF-α, TNF-β and IFN-γ) were assessed by flow cytometry and ELISA. The number of total lymphocytes, CD4+ T and NK cells in the peripheral blood significantly decreased 24 h after MWA, while number of CD8+ T cells remained stable, leading to a higher proportion of CD8+ T cells. In addition, the serum levels of IL-2, IL-1β, IL-6, IL-12p70, IL-22, TNF-α and IFN-γ were significantly increased 24 h after MWA, indicating a T helper 1 type immune response. The immune response in patients with advanced stage disease was comparable with patients in the early stage group; however, the number of total lymphocytes and CD3+ T cells significantly decreased and the ratio of CD4/CD8 and IL-2 levels significantly increased. The early immune response after MWA may contribute to systemic antitumor immunity in patients with both early and advanced disease. Thus, MWA may exhibit potential as a local therapy and trigger abscopal effects in distant lesions in patients with lung cancer.

Focused ultrasound ablation of melanoma with boiling histotripsy yields abscopal tumor control and antigen-dependent dendritic cell activation

Background: Boiling histotripsy (BH), a mechanical focused ultrasound ablation strategy, can elicit intriguing signatures of anti-tumor immunity. However, the influence of BH on dendritic cell function is unknown, compromising our ability to optimally combine BH with immunotherapies to control metastatic disease. Methods: BH was applied using a sparse scan (1 mm spacing between sonications) protocol to B16F10-ZsGreen melanoma in bilateral and unilateral settings. Ipsilateral and contralateral tumor growth was measured. Flow cytometry was used to track ZsGreen antigen and assess how BH drives dendritic cell behavior. Results: BH monotherapy elicited ipsilateral and abscopal tumor control in this highly aggressive model. Tumor antigen presence in immune cells in the tumor-draining lymph nodes (TDLNs) was ~3-fold greater at 24h after BH, but this abated by 96h. B cells, macrophages, monocytes, granulocytes, and both conventional dendritic cell subsets (i.e. cDC1s and cDC2s) acquired markedly more antigen with BH. BH drove activation of both cDC subsets, with activation being dependent upon tumor antigen acquisition. Our data also suggest that BH-liberated tumor antigen is complexed with damage-associated molecular patterns (DAMPs) and that cDCs do not traffic to the TDLN with antigen. Rather, they acquire antigen as it flows through afferent lymph vessels into the TDLN. Conclusion: When applied with a sparse scan protocol, BH monotherapy elicits abscopal melanoma control and shapes dendritic cell function through several previously unappreciated mechanisms. These results offer new insight into how to best combine BH with immunotherapies for the treatment of metastatic melanoma.

Healing Process after High-Intensity Focused Ultrasound Treatment of Benign Skin Lesions: Dermoscopic Analysis and Treatment Guidelines

Background: High-Intensity Focused Ultrasound (HIFU) has emerged as a precise and non-invasive modality for tissue ablation and healing. This study presents a detailed dermoscopic analysis of skin healing post-High-Intensity Focused Ultrasound (HIFU) treatment, focusing on common benign skin lesions, such as seborrheic keratosis, sebaceous hyperplasia, vascular lesions, and sebaceous nevi. Methods: Prior to HIFU treatment, a comprehensive assessment was conducted, integrating ultrasound scanning and clinical evaluations. The TOOsonix System ONE-M was employed for HIFU treatments, with parameters tailored to each lesion type. Results: A common pattern observed across all lesions includes initial whitening post treatment, followed by scab formation and the development of a pink area with reparative vessels. This study, however, highlights distinct differences in fibrosis patterns and healing timelines across different lesion types. Each lesion type exhibited unique fibrosis patterns post treatment. Flatter variants of seborrheic keratosis healed within a month, displaying hypopigmentation and reparative vessels, alongside a distinct lattice fibrosis pattern in more verrucous forms, which took about two months to heal. Sebaceous hyperplasia, characterized by rapid healing within three weeks, demonstrated fibrosis with pink areas and perpendicular white lines, concluding with a slight depression. Vascular lesions varied in healing time based on depth, with superficial ones showing whitening and crust formation, while deeper lesions had vessel occlusion and size reduction accompanied by concentric fibrotic bands. Sebaceous nevi presented the longest healing duration of three months, characterized by amorphous white-gray structures, scab formation, and the emergence of pink areas with branching vessels, leading to clear skin with reduced white lines. Conclusions: in conclusion, this meticulous clinical evaluation highlights the unique healing characteristics and timelines for each skin lesion type treated with HIFU. These insights are invaluable for optimizing follow-up assessments, identifying potential complications, and refining treatment protocols. By providing detailed insights into the healing timelines and patterns for different types of lesions, patients can be better informed about their post-treatment journey.

Ultrasound robotics for precision therapy

In recent years, the application of microrobots in precision therapy has gained significant attention. The small size and maneuverability of these micromachines enable them to potentially access regions that are difficult to reach using traditional methods; thus, reducing off-target toxicities and maximizing treatment effectiveness. Specifically, acoustic actuation has emerged as a promising method to exert control. By harnessing the power of acoustic energy, these small machines potentially navigate the body, assemble at the desired sites, and deliver therapies with enhanced precision and effectiveness. Amidst the enthusiasm surrounding these miniature agents, their translation to clinical environments has proven difficult. The primary objectives of this review are threefold: firstly, to offer an overview of the fundamental acoustic principles employed in the field of microrobots; secondly, to assess their current applications in medical therapies, encompassing tissue targeting, drug delivery or even cell infiltration; and lastly, to delve into the continuous efforts aimed at integrating acoustic microrobots into in vivo applications.

Aptamer-Based Smart Targeting and Spatial Trigger-Response Drug-Delivery Systems for Anticancer Therapy

In recent years, the field of drug delivery has witnessed remarkable progress, driven by the quest for more effective and precise therapeutic interventions. Among the myriad strategies employed, the integration of aptamers as targeting moieties and stimuli-responsive systems has emerged as a promising avenue, particularly in the context of anticancer therapy. This review explores cutting-edge advancements in targeted drug-delivery systems, focusing on the integration of aptamers and stimuli-responsive platforms for enhanced spatial anticancer therapy. In the aptamer-based drug-delivery systems, we delve into the versatile applications of aptamers, examining their conjugation with gold, silica, and carbon materials. The synergistic interplay between aptamers and these materials is discussed, emphasizing their potential in achieving precise and targeted drug delivery. Additionally, we explore stimuli-responsive drug-delivery systems with an emphasis on spatial anticancer therapy. Tumor microenvironment-responsive nanoparticles are elucidated, and their capacity to exploit the dynamic conditions within cancerous tissues for controlled drug release is detailed. External stimuli-responsive strategies, including ultrasound-mediated, photo-responsive, and magnetic-guided drug-delivery systems, are examined for their role in achieving synergistic anticancer effects. This review integrates diverse approaches in the quest for precision medicine, showcasing the potential of aptamers and stimuli-responsive systems to revolutionize drug-delivery strategies for enhanced anticancer therapy.

Local ablative therapies and the effect on antitumor immune responses in pancreatic cancer - A review

Pancreatic ductal adenocarcinoma (PDAC) is a devastating disease, projected to rank as the second most prevalent cause of cancer-related mortality by 2030. Despite significant progress in advances in surgical techniques and chemotherapy protocols, the overall survival (OS) remains to be less than 10 % for all stages combined. In recent years, local ablative techniques have been introduced and utilized as additional therapeutic approaches for locally advanced pancreatic cancer (LAPC), with promising results with respect to local tumor control and OS. In addition to successful cytoreduction, there is emerging evidence that local ablation induces antitumor immune activity that could prevent or even treat distant metastatic tumors. The enhancement of antitumor immune responses could potentially make ablative therapy a therapeutic option for the treatment of metastatic PDAC. In this review, we summarize current ablative techniques used in the management of LAPC and their impact on systemic immune responses.

Focused ultrasound ablation of melanoma with boiling histotripsy yields abscopal tumor control and antigen-dependent dendritic cell activation

Background

Boiling histotripsy (BH), a mechanical focused ultrasound ablation strategy, can elicit intriguing signatures of anti-tumor immunity. However, the influence of BH on dendritic cell function is unknown, compromising our ability to optimally combine BH with immunotherapies to control metastatic disease.

Methods

BH was applied using a sparse scan (1 mm spacing between sonications) protocol to B16F10-ZsGreen melanoma in bilateral and unilateral settings. Ipsilateral and contralateral tumor growth was measured. Flow cytometry was used to track ZsGreen antigen and assess how BH drives dendritic cell behavior.

Results

BH monotherapy elicited ipsilateral and abscopal tumor control in this highly aggressive model. Tumor antigen presence in immune cells in the tumor-draining lymph nodes (TDLNs) was ~3-fold greater at 24h after BH, but this abated by 96h. B cells, macrophages, monocytes, granulocytes, and both conventional dendritic cell subsets (i.e. cDC1s and cDC2s) acquired markedly more antigen with BH. BH drove activation of both cDC subsets, with activation being dependent upon tumor antigen acquisition. Our data also suggest that BH-liberated tumor antigen is complexed with damage-associated molecular patterns (DAMPs) and that cDCs do not traffic to the TDLN with antigen. Rather, they acquire antigen as it flows through afferent lymph vessels into the TDLN.

Conclusion

When applied with a sparse scan protocol, BH monotherapy elicits abscopal melanoma control and shapes dendritic cell function through several previously unappreciated mechanisms. These results offer new insight into how to best combine BH with immunotherapies for the treatment of metastatic melanoma.

Engineering Versatile Nanomedicines for Ultrasonic Tumor Immunotherapy

Due to the specific advantages of ultrasound (US) in therapeutic disease treatments, the unique therapeutic US technology has emerged. In addition to featuring a low-invasive targeted cancer-cell killing effect, the therapeutic US technology has been demonstrated to modulate the tumor immune landscape, amplify the therapeutic effect of other antitumor therapies, and induce immunosensitization of tumors to immunotherapy, shedding new light on the cancer treatment. Tremendous advances in nanotechnology are also expected to bring unprecedented benefits to enhancing the antitumor efficiency and immunological effects of therapeutic US, as well as therapeutic US-derived bimodal and multimodal synergistic therapies. This comprehensive review summarizes the immunological effects induced by different therapeutic US technologies, including ultrasound-mediated micro-/nanobubble destruction (UTMD/UTND), sonodynamic therapy (SDT), and focused ultrasound (FUS), as well as the main underlying mechanisms involved. It is also discussed that the recent research progress of engineering intelligent nanoplatform in improving the antitumor efficiency of therapeutic US technologies. Finally, focusing on clinical translation, the key issues and challenges currently faced are summarized, and the prospects for promoting the clinical translation of these emerging nanomaterials and ultrasonic immunotherapy in the future are proposed.

Blood-cerebrospinal fluid barrier opening by modified single pulse transcranial focused shockwave

Transcranial focused shockwave (FSW) is a novel noninvasive brain stimulation that can open blood-brain barriers (BBB) and blood-cerebrospinal fluid barriers (BCSFB) with a single low-energy (energy flux density 0.03 mJ/mm²) pulse and low-dose microbubbles (2 × 10⁶/kg). Similar to focused ultrasound, FSW deliver highly precise stimulation of discrete brain regions with adjustable focal lengths that essentially covers the whole brain. By opening the BCSFB, it allows for rapid widespread drug delivery to the whole brain by cerebrospinal fluid (CSF) circulation. Although no definite adverse effect or permeant injury was noted in our previous study, microscopic hemorrhage was infrequently observed. Safety concerns remain the major obstacle to further application of FSW in brain. To enhance its applicability, a modified single pulse FSW technique was established that present 100% opening rate but much less risk of adverse effect than previous methods. By moving the targeting area 2.5 mm more superficially on the left lateral ventricle as compared with the previous methods, the microscopic hemorrhage rate was reduced to zero. We systemically examine the safety profiles of the modified FSW-BCSFB opening regarding abnormal behavior and brain injury or hemorrhage 72 hr after 0, 1, and 10 pulses of FSW-treatment. Animal behavior, physiological monitor, and brain MRI were examined and recorded. Brain section histology was examined for hemorrhage, apoptosis, inflammation, oxidative stress related immunohistochemistry and biomarkers. The single pulse FSW group demonstrated no mortality or gross/microscopic hemorrhage (N = 30), and no observable changes in all examined outcomes, while 10 pulses of FSW was found to be associated with microscopic and temporary RBC extravasation (N = 6/30), and abnormal immunohistochemistry biomarkers which showed a trend of recovery at 72 hrs. The results suggest that single pulse low-energy FSW-BCSFB opening is effective, safe and poses minimal risk of injury to brain tissue (Sprague Dawley, SD rats).

Endoluminal radiofrequency ablation in patients with malignant biliary obstruction: a randomised trial

BACKGROUND

Endoluminal radiofrequency ablation (RFA) has been promoted as palliative treatment for patients with cholangiocarcinoma (CCA) and pancreatic ductal adenocarcinoma (PDAC) in order to improve biliary drainage and eventually prolong survival. No high level evidence is, however, available on this technique.

DESIGN

In this randomised controlled study, we compared endoluminal RFA plus stenting with stenting alone (control group) in patients with malignant biliary obstruction; metal stents were primarily placed. Primary outcome was overall survival; secondary outcomes were stent patency, quality of life and adverse events. In a superiority design, survival was assumed to be doubled by RFA as compared with 6.4 months in the control group (n=280).

RESULTS

A total of 161 patients (male:female 90:71, mean age 71±9 years) were randomised before recruitment was terminated for futility after an interim analysis. Eighty-five patients had CCA (73 hilar, 12 distal) and 76 had pancreatic cancer. There was no difference in survival in both subgroups: for patients with CCA, median survival was 10.5 months (95% CI 6.7 to 18.3) in the RFA group vs 10.6 months (95% CI 9.0 to 24.8), p=0.58)) in the control group. In the subgroup with pancreatic cancer, median survival was 6.4 months (95% CI 4.3 to 9.7) for the RFA vs 7.7 months (95% CI 5.6 to 11.3), p=0.73) for the control group. No benefit was seen in the RFA group with regard to stent patency (at 12 months 40% vs 36% in CCA and 66% vs 65% in PDAC), and quality of life was unchanged by either treatment and comparable between the groups. Adverse events occurred in seven patients in each groups.

CONCLUSION

A combination of endoluminal RFA and stenting was not superior to stenting alone in prolonging survival or improving stent patency in patients with malignant biliary obstruction.

TRIAL REGISTRATION NUMBER

NCT03166436.

Deep-Learning-Based High-Intensity Focused Ultrasound Lesion Segmentation in Multi-Wavelength Photoacoustic Imaging

Photoacoustic (PA) imaging can be used to monitor high-intensity focused ultrasound (HIFU) therapies because ablation changes the optical absorption spectrum of the tissue, and this change can be detected with PA imaging. Multi-wavelength photoacoustic (MWPA) imaging makes this change easier to detect by repeating PA imaging at multiple optical wavelengths and sampling the optical absorption spectrum more thoroughly. Real-time pixel-wise classification in MWPA imaging can assist clinicians in monitoring HIFU lesion formation and will be a crucial milestone towards full HIFU therapy automation based on artificial intelligence. In this paper, we present a deep-learning-based approach to segment HIFU lesions in MWPA images. Ex vivo bovine tissue is ablated with HIFU and imaged via MWPA imaging. The acquired MWPA images are then used to train and test a convolutional neural network (CNN) for lesion segmentation. Traditional machine learning algorithms are also trained and tested to compare with the CNN, and the results show that the performance of the CNN significantly exceeds traditional machine learning algorithms. Feature selection is conducted to reduce the number of wavelengths to facilitate real-time implementation while retaining good segmentation performance. This study demonstrates the feasibility and high performance of the deep-learning-based lesion segmentation method in MWPA imaging to monitor HIFU lesion formation and the potential to implement this method in real time.

Radiation combined with ultrasound and microbubbles: A potential novel strategy for cancer treatment

Cancer is one of the leading causes of death worldwide. Several emerging technologies are helping to battle cancer. Cancer therapies have been effective at killing cancer cells, but a large portion of patients still die to this disease every year. As such, more aggressive treatments of primary cancers are employed and have been shown to be capable of saving a greater number of lives. Recent research advances the field of cancer therapy by employing the use of physical methods to alter tumor biology. It uses microbubbles to enhance radiation effect by damaging tumor vasculature followed by tumor cell death. The technique can specifically target tumor volumes by conforming ultrasound fields capable of microbubbles stimulation and localizing it to avoid vascular damage in surrounding tissues. Thus, this new application of ultrasound-stimulated microbubbles (USMB) can be utilized as a novel approach to cancer therapy by inducing vascular disruption resulting in tumor cell death. Using USMB alongside radiation has showed to augment the anti-vascular effect of radiation, resulting in enhanced tumor response. Recent work with nanobubbles has shown vascular permeation into intracellular space, extending the use of this new treatment method to potentially further improve the therapeutic effect of the ultrasound-based therapy. The significant enhancement of localized tumor cell kill means that radiation-based treatments can be made more potent with lower doses of radiation. This technique can manifest a greater impact on radiation oncology practice by increasing treatment effectiveness significantly while reducing normal tissue toxicity. This review article summarizes the past and recent advances in USMB enhancement of radiation treatments. The review mainly focuses on preclinical findings but also highlights some clinical findings that use USMB as a therapeutic modality in cancer therapy.

High-intensity focused ultrasound versus transarterial chemoembolization for hepatocellular carcinoma: a meta-analysis

PURPOSE

The application of high-intensity focused ultrasound (HIFU) in hepatocellular carcinoma (HCC) was promising. However, whether the effect of HIFU is comparable with that of transarterial chemoembolization (TACE) has not been determined.

MATERIALS AND METHODS

PubMed, Embase, Cochrane Library, Web of Science, WanFang Data, CqVip, CNKI, and CBM databases were searched for randomized controlled trials (RCTs), cohort studies, and case-control studies. The methodological quality of each study was evaluated. When there is no statistical heterogeneity, the fixed effect model would be used to merge data. Otherwise, the random effect model would be utilized. Sensitivity analyses were conducted by excluding one study each time. Subgroup analyses were conducted based on age, sex, tumor number, relative number of the patients with Child-Pugh C grade in each group, the percentage of patients with Child-Pugh C grade in the whole study, and tumor load. Publication bias was evaluated by Egger's test and Begg's test.

RESULTS

Six cohort studies including 188 patients from HIFU group and 224 patients from TACE group were obtained for further analysis. The meta-analysis suggested HIFU and TACE showed no differences in postoperative 1-year overall survival (OS) rate, tumor response (including complete response, partial response, stable disease, and progressive disease), and postoperative complications. Moreover, compared with TACE, HIFU showed higher postoperative 6-month and 2-year OS rates. Subgroup analyses, meta regression analysis and sensitivity analyses indicated the findings above were reliable. Additionally, no potential publication bias was detected.

CONCLUSION

For HCC, when compared with TACE, HIFU might show comparable safety but better effect. Considering the limitations of current studies, more well-designed studies are needed to validate our conclusion.

Study on the effect of a triple cancer treatment of propolis, thermal cycling-hyperthermia, and low-intensity ultrasound on PANC-1 cells

To reduce side effects and enhance treatment efficacy, study on combination therapy for pancreatic cancer, a deadly cancer, has gained much attraction in recent years. In this study, we propose a novel triple treatment combining propolis and two physical stimuli-thermal cycling-hyperthermia (TC-HT) and low-intensity ultrasound (US). The study found that, after the triple treatment, the cell viability of a human cancer cell line PANC-1 decreased to a level 80% less than the control, without affecting the normal pancreatic cells. Another result was excessive accumulation of reactive oxygen species (ROS) after the triple treatment, leading to the amplification of apoptotic pathway through the MAPK family and mitochondrial dysfunction. This study, to the best of our knowledge, is the first attempt to combine TC-HT, US, and a natural compound in cancer treatment. The combination of TC-HT and US also promotes the anticancer effect of the heat-sensitive chemotherapy drug cisplatin on PANC-1 cells. It is expected that optimized parameters for different agents and different types of cancer will expand the methodology on oncological therapy in a safe manner.

T-lymphocytes from focused ultrasound ablation subsequently mediate cellular antitumor immunity after adoptive cell transfer immunotherapy

Background

Our previous studies found that high-intensity focused ultrasound (HIFU) stimulated tumor-specific T cells in a mouse H22 tumor model, and adoptive transfer of the T cells from HIFU-treated mice could subsequently elicit stronger inhibition on the growth and progression of the implanted tumors. The aim of this study was to investigate the mechanism of T cells from focused ultrasound ablation in HIFU-mediated immunomodulation.

Methods

Sixty H22 tumor-bearing mice were treated by either HIFU or sham-HIFU, and 30 naïve syngeneic mice served as controls. All mice were euthanized on day 14 after HIFU and splenic T cell suspensions were obtained in each group. Using an adoptive cell transfer model, a total of 1 × 106 T cells from HIFU treated-mice were intravenously injected into each syngeneic H22 tumor-bearing mouse twice on day 3 and 4, followed by the sacrifice for immunological assessments at 14 days after the adoptive transfer.

Results

T cells from HIFU-treated mice could significantly enhance the cytotoxicity of CTLs (p < 0.001), with a significant increase of TNF-α (p < 0.001) and IFN-γ secretion (p < 0.001). Compared to control and sham-HIFU groups, the number of Fas ligand+ and perforin+ tumor-infiltrating lymphocytes (TILs) and apoptotic H22 tumor cells were significantly higher (p < 0.001) in the HIFU group. There were linear correlations between apoptotic tumor cells and Fas ligand+ TILs (r = 0.9145, p < 0.001) and perforin+ TILs (r = 0.9619, p < 0.001).

Conclusion

T cells from HIFU-treated mice can subsequently mediate cellular antitumor immunity, which may play an important role in the HIFU-based immunomodulation.

High Intensity Focused Ultrasound Ablation for Patients With Locally Advanced Pancreatic Adenocarcinoma: A Propensity Score-Matching Analysis

OBJECTIVES

This retrospective study was conducted to assess the efficacy and safety of high intensity focused ultrasound (HIFU) in combination with chemotherapy compared with chemotherapy alone in treating patients with unresectable locally advanced pancreatic cancer (LAPC).

METHODS

The data of unresectable LAPC patients who received chemotherapy with or without HIFU ablation were retrieved retrospectively. The overall survival (OS), objective response rate (ORR), cancer antigen 19-9 response rate, and safety were compared between these two groups before and after propensity score matching (PSM).

RESULTS

Overall, 254 patients with LAPC were included, of whom 92 underwent HIFU ablation. After PSM to control for potential biases, HIFU was associated with improved OS (12.8 versus 12.2 months, log-rank P = .046), as compared to patients without HIFU ablation. Patients with numeric rating scale (NRS) less than 4, and receiving HIFU ablation were significantly associated with improved OS (adjusted hazard ratio [aHR] = 0.365 [95% confidence interval (CI) = 0.148-0.655], P = .002; aHR = 0.490 [95% CI = 0.250-0.961], P = .038; respectively) by multivariate analyses with the adjustment of age, NRS, and tumor size. ORR was also observed to be higher in HIFU group of 30.0% than in the chemotherapy group of 13.3% (P = .039). No severe adverse events of special interest or HIFU-caused deaths were observed.

CONCLUSIONS

Patients with unresectable LAPC who received gemcitabine-based chemotherapy might benefit from additional HIFU ablation.

Noninvasive mechanical destruction of liver tissue and tissue decellularisation by pressure-modulated shockwave histotripsy

Introduction

Boiling histotripsy (BH) is a promising High Intensity Focused Ultrasound (HIFU) technique that can be used to mechanically fractionate solid tumours at the HIFU focus noninvasively, promoting tumour immunity. Because of the occurrence of shock scattering phenomenon during BH process, the treatment accuracy of BH is, however, somewhat limited. To induce more localised and selective tissue destruction, the concept of pressure modulation has recently been proposed in our previous in vitro tissue phantom study. The aim of the present study was therefore to investigate whether this newly developed histotripsy approach termed pressure-modulated shockwave histotripsy (PSH) can be used to induce localised mechanical tissue fractionation in in vivo animal model.

Methods

In the present study, 8 Sprague Dawley rats underwent the PSH treatment and were sacrificed immediately after the exposure for morphological and histological analyses (paraffin embedded liver tissue sections were stained with H&E and MT). Partially exteriorised rat's left lateral liver lobe in vivo was exposed to a 2.0 MHz HIFU transducer with peak positive (P ₊) and negative (P _-) pressures of 89.1 MPa and -14.6 MPa, a pulse length of 5 to 34 ms, a pressure modulation time at 4 ms where P ₊ and P _- decreased to 29.9 MPa and - 9.6 MPa, a pulse repetition frequency of 1 Hz, a duty cycle of 1% and number of pulses of 1 to 20. Three lesions were produced on each animal. For comparison, the same exposure condition but no pressure modulation was also employed to create a number of lesions in the liver.

Results and Discussion

Experimental results showed that a partial mechanical destruction of liver tissue in the form of an oval in the absence of thermal damage was clearly observed at the HIFU focus after the PSH exposure. With a single pulse length of 7 ms, a PSH lesion created in the liver was measured to be a length of 1.04 ± 0.04 mm and a width of 0.87 ± 0.21 mm which was 2.37 times in length (p = 0.027) and 1.35 times in width (p = 0.1295) smaller than a lesion produced by no pressure modulation approach (e.g., BH). It was also observed that the length of a PSH lesion gradually grew towards the opposite direction to the HIFU source along the axial direction with the PSH pulse length, eventually leading to the generation of an elongated lesion in the liver. In addition, our experimental results demonstrated the feasibility of inducing partial decellularisation effect where liver tissue was partially destructed with intact extracellular matrix (i.e., intact fibrillar collagen) with the shortest PSH pulse length. Taken together, these results suggest that PSH could be used to induce a highly localised tissue fractionation with a desired degree of mechanical damage from complete tissue fractionation to tissue decellularisation through controlling the dynamics of boiling bubbles without inducing the shock scattering effect.

Immunomodulatory effect of locoregional therapy in the tumor microenvironment

Cancer immunotherapy appears to be a promising treatment option; however, only a subset of patients with cancer responds favorably to treatment. Locoregional therapy initiates a local antitumor immune response by disrupting immunosuppressive components, releasing immunostimulatory damage-associated molecular patterns, recruiting immune effectors, and remodeling the tumor microenvironment. Many studies have shown that locoregional therapy can produce specific antitumor immunity alone; nevertheless, the effect is relatively weak and transient. Furthermore, increasing research efforts have explored the potential synergy between locoregional therapy and immunotherapy to enhance the long-term systemic antitumor immune effect and improve survival. Therefore, further research is needed into the immunomodulatory effects of locoregional therapy and immunotherapy to augment antitumor effects. This review article summarizes the key components of the tumor microenvironment, discusses the immunomodulatory role of locoregional therapy in the tumor microenvironment, and emphasizes the therapeutic potential of locoregional therapy in combination with immune checkpoint inhibitors.

Mechanical High-Intensity Focused Ultrasound (Histotripsy) in Dogs With Spontaneously Occurring Soft Tissue Sarcomas

INTRODUCTION

Histotripsy is a non-invasive focused ultrasound therapy that uses controlled acoustic cavitation to mechanically disintegrate tissue. To date, there are no reports investigating histotripsy for the treatment of soft tissue sarcoma (STS).

OBJECTIVE

This study aimed to investigate the in vivo feasibility of ablating STS with histotripsy and to characterize the impact of partial histotripsy ablation on the acute immunologic response in canine patients with spontaneous STS.

METHODS

A custom 500 kHz histotripsy system was used to treat ten dogs with naturally occurring STS. Four to six days after histotripsy, tumors were surgically resected. Safety was determined by monitoring vital signs during treatment and post-treatment physical examinations, routine lab work, and owners' reports. Ablation was characterized using radiologic and histopathologic analyses. Systemic immunological impact was evaluated by measuring changes in cytokine concentrations, and tumor microenvironment changes were evaluated by characterizing changes in infiltration with tumor-associated macrophages (TAMs) and tumor-infiltrating lymphocytes (TILs) using multiplex immunohistochemistry and differential gene expression.

RESULTS

Results showed histotripsy ablation was achievable and well-tolerated in all ten dogs. Immunological results showed histotripsy induced pro-inflammatory changes in the tumor microenvironment. Conclusion & Significance: Overall, this study demonstrates histotripsy's potential as a precise, non-invasive treatment for STS.

Mechanical destruction using a minimally invasive Ultrasound Needle induces anti-tumor immune responses and synergizes with the anti-PD-L1 blockade

Immune checkpoint inhibitors (ICIs) have been widely used in treating various tumors; however, the objective response rate of ICIs is less than 40%. In this study, we attempted to induce anti-tumor immune responses using an improved ultrasonic horn device, Ultrasound Needle (UN). We tested its synergistic anti-tumor efficacy with an anti-PD-L1 antibody in a mouse tumor model. Under different parameters, UN treatment selectively induced mechanical destruction and thermal ablation effects on tumor tissues. The mechanical destruction effect of UN treatment increased the infiltration of CD8⁺ T cells in tumors and relieved the immunosuppressive tumor microenvironment. It also induced systemic anti-tumor immune responses and enhanced the therapeutic efficacy of the anti-PD-L1 antibody in both local and abscopal tumors. The mechanical destruction effect of UN treatment resulted in the release of damage-associated molecular patterns and promoted dendritic cells (DCs)-based antigen presentation. Depletion of DCs or CD8⁺ T cells eliminated the anti-tumor immune responses induced by UN treatment and weakened the synergistic anti-tumor efficacy with anti-PD-L1 antibody. Therefore, minimally invasive UN may provide a new therapeutic modality for ultrasound-assisted immunotherapy.

Use of stimulatory responsive soft nanoparticles for intracellular drug delivery

Drug delivery has made tremendous advances in the last decade. Targeted therapies are increasingly common, with intracellular delivery highly impactful and sought after. Intracellular drug delivery systems have limitations due to imprecise and non-targeted release profiles. One way this can be addressed is through using stimuli-responsive soft nanoparticles, which contain materials with an organic backbone such as lipids and polymers. The choice of biomaterial is essential for soft nanoparticles to be responsive to internal or external stimuli. The nanoparticle must retain its integrity and payload in non-targeted physiological conditions while responding to particular intracellular environments where payload release is desired. Multiple internal and external factors could stimulate the intracellular release of drugs from nanoparticles. Internal stimuli include pH, oxidation, and enzymes, while external stimuli include ultrasound, light, electricity, and magnetic fields. Stimulatory responsive soft nanoparticulate systems specifically utilized to modulate intracellular delivery of drugs are explored in this review.

Mechanical stimuli-driven cancer therapeutics

Mechanical stimulation utilizing deep tissue-penetrating and focusable energy sources, such as ultrasound and magnetic fields, is regarded as an emerging patient-friendly and effective therapeutic strategy to overcome the limitations of conventional cancer therapies based on fundamental external stimuli such as light, heat, electricity, radiation, or microwaves. Recent efforts have suggested that mechanical stimuli-driven cancer therapy (henceforth referred to as "mechanical cancer therapy") could provide a direct therapeutic effect and intelligent control to augment other anti-cancer systems as a synergistic combinational cancer treatment. This review article highlights the latest advances in mechanical cancer therapy to present a novel perspective on the fundamental principles of ultrasound- and magnetic field-mediated mechanical forces, including compression, tension, shear force, and torque, that can be generated in a cellular microenvironment using mechanical stimuli-activated functional materials. Additionally, this article will shed light on mechanical cancer therapy and inspire future research to pursue the development of ultrasound- and magnetic-field-activated materials and their applications in this field.

The analysis of immunogenic cell death induced by ablation at different temperatures in hepatocellular carcinoma cells

Introduction: Ablation therapy is a commonly used tool in the management of hepatocellular carcinoma (HCC). After ablation, dying cancer cells release a variety of substances that trigger subsequent immune responses. Immunogenic cell death (ICD) has been a trending topic in recent years and has been discussed many times along with oncologic chemotherapy. However, the subject of ablative therapy and ICDs has been little discussed. The purpose of this study was to investigate whether ablation treatment induces ICD in HCC cells and whether different types of ICDs arise because of different ablation temperatures. Methods: Four different HCC cell lines (H22, Hepa-16, HepG2 and SMMC7221) were cultured and treated under different temperatures (-80°C, -40°C, 0°C, 37°C, and 60°C). Cell Counting Kit-8 assay was performed to analyze the viability of different cell lines. Apoptosis was detected by flow cytometry assay, and a few ICD-related cytokines (calreticulin, ATP, high mobility group box 1, and CXCL10) were detected by immunofluorescence or enzyme-linked immunosorbent assay. Results: The apoptosis rate of all kinds of cells increased significantly in -80°C group (p < 0.01) and 60°C group (p < 0.01). The expression levels of ICD-related cytokines were mostly significantly different between the different groups. For calreticulin, Hepa1-6 cells and SMMC7221 cells showed significantly higher protein expression levels in 60°C group (p < 0.01) and significantly lower protein expression levels -80°C group (p < 0.01). The ATP, high mobility group box 1 and CXCL10 expression levels were significantly higher in 60°C, -80°C and -40°C group of all four cell lines (p < 0.01). Conclusion: Different ablative treatments could induce different types of ICDs in HCC cells, providing a promising track for the development of individualized cancer therapies.

A radiomics nomogram model for predicting prognosis of pancreatic ductal adenocarcinoma after high-intensity focused ultrasound surgery

OBJECTIVE

To develop and validate a radiomics nomogram for predicting the survival of patients with pancreatic ductal adenocarcinoma (PDAC) after receiving high-intensity focused ultrasound (HIFU) treatment.

METHODS

A total of 52 patients with PDAC were enrolled. To select features, the least absolute shrinkage and selection operator algorithm were applied, and the radiomics score (Rad-Score) was obtained. Radiomics model, clinics model, and radiomics nomogram model were constructed by multivariate regression analysis. The identification, calibration, and clinical application of nomogram were evaluated. Survival analysis was performed using Kaplan-Meier (K-M) method.

RESULTS

According to conclusions made from the multivariate Cox model, Rad-Score, and tumor size were independent risk factors for OS. Compared with the clinical model and radiomics model, the combination of Rad-Score and clinicopathological factors could better predict the survival of patients. Patients were divided into high-risk and low-risk groups according to Rad-Score. K-M analysis showed that the difference between the two groups was statistically significant (p < 0.05). In addition, the radiomics nomogram model indicated better discrimination, calibration, and clinical practicability in training and validation cohorts.

CONCLUSION

The radiomics nomogram effectively evaluates the prognosis of patients with advanced pancreatic cancer after HIFU surgery, which could potentially improve treatment strategies and promote individualized treatment of advanced pancreatic cancer.

Gaseous nitric oxide tumor ablation induces an anti-tumor abscopal effect

BACKGROUND

In-situ tumor ablation provides the immune system with the appropriate antigens to induce anti-tumor immunity. Here, we present an innovative technique for generating anti-tumor immunity by delivering exogenous ultra-high concentration (> 10,000 ppm) gaseous nitric oxide (UHCgNO) intratumorally.

METHODS

The capability of UHCgNO to induce apoptosis was tested in vitro in mouse colon (CT26), breast (4T1) and Lewis lung carcinoma (LLC-1) cancer cell lines. In vivo, UHCgNO was studied by treating CT26 tumor-bearing mice in-situ and assessing the immune response using a Challenge assay.

RESULTS

Exposing CT26, 4T1 and LLC-1 cell lines to UHCgNO for 10 s-2.5 min induced cellular apoptosis 24 h after exposure. Treating CT26 tumors in-situ with UHCgNO followed by surgical resection 14 days later resulted in a significant secondary anti-tumor effect in vivo. 100% of tumor-bearing mice treated with 50,000 ppm UHCgNO and 64% of mice treated with 20,000 ppm UHCgNO rejected a second tumor inoculation, compared to 0% in the naive control for 70 days. Additionally, more dendrocytes infiltrated the tumor 14 days post UHCgNO treatment versus the nitrogen control. Moreover, T-cell penetration into the primary tumor was observed in a dose-dependent manner. Systemic increases in T- and B-cells were seen in UHCgNO-treated mice compared to nitrogen control. Furthermore, polymorphonuclear-myeloid-derived suppressor cells were downregulated in the spleen in the UHCgNO-treated groups.

CONCLUSIONS

Taken together, our data demonstrate that UHCgNO followed by the surgical removal of the primary tumor 14 days later induces a strong and potent anti-tumor response.

Mechanical high-intensity focused ultrasound creates unique tumor debris enhancing dendritic cell-induced T cell activation

Introduction

In situ tumor ablation releases a unique repertoire of antigens from a heterogeneous population of tumor cells. High-intensity focused ultrasound (HIFU) is a completely noninvasive ablation therapy that can be used to ablate tumors either by heating (thermal (T)-HIFU) or by mechanical disruption (mechanical (M)-HIFU). How different HIFU ablation techniques compare with respect to their antigen release profile, their activation of responder T cells, and their ability to synergize with immune stimuli remains to be elucidated.

Methods and results

Here, we compare the immunomodulatory effects of T-HIFU and M-HIFU ablation with or without the TLR9 agonist CpG in the ovalbumin-expressing lymphoma model EG7. M-HIFU ablation alone, but much less so T-HIFU, significantly increased dendritic cell (DC) activation in draining lymph nodes (LNs). Administration of CpG following T- or M-HIFU ablation increased DC activation in draining LNs to a similar extend. Interestingly, ex vivo co-cultures of draining LN suspensions from HIFU plus CpG treated mice with CD8⁺ OT-I T cells demonstrate that LN cells from M-HIFU treated mice most potently induced OT-I proliferation. To delineate the mechanism for the enhanced anti-tumor immune response induced by M-HIFU, we characterized the RNA, DNA and protein content of tumor debris generated by both HIFU methods. M-HIFU induced a uniquely altered RNA, DNA and protein profile, all showing clear signs of fragmentation, whereas T-HIFU did not. Moreover, western blot analysis showed decreased levels of the immunosuppressive cytokines IL-10 and TGF-β in M-HIFU generated tumor debris compared to untreated tumor tissue or T-HIFU.

Conclusion

Collectively, these results imply that M-HIFU induces a unique context of the ablated tumor material, enhancing DC-mediated T cell responses when combined with CpG.

Acoustic and Thermal Characterization of Therapeutic Ultrasonic Langevin Transducers under Continuous- and Pulsed Wave Excitations

We previously conducted an empirical study on Langevin type transducers in medical use by examining the heat effect on porcine tissue. For maximum acoustic output, the transducer was activated by a continuous sinusoidal wave. In this work, pulsed waves with various duty factors were applied to our transducer model in order to examine their effect on functionality. Acoustic power, electro-acoustic conversion efficiency, acoustic pressure, thermal effect on porcine tissue and bovine muscle, and heat generation in the transducer were investigated under various input conditions. For example, the results of applying a continuous wave of 200 V_PP and a pulse wave of 70% duty factor with the same amplitude to the transducer were compared. It was found that continuous waves generated 9.79 W of acoustic power, 6.40% energy efficiency, and 24.84 kPa acoustic pressure. In pulsed excitation, the corresponding values were 9.04 W, 8.44%, and 24.7 kPa, respectively. The maximum temperature increases in bovine muscle are reported to be 83.0 °C and 89.5 °C for each waveform, whereas these values were 102.5 °C and 84.5 °C in fatty porcine tissue. Moreover, the heat generation around the transducer was monitored under continuous and pulsed modes and was found to be 51.3 °C and 50.4 °C. This shows that pulsed excitation gives rise to less thermal influence on the transducer. As a result, it is demonstrated that a transducer triggered by pulsed waves improves the energy efficiency and provides sufficient thermal impact on biological tissues by selecting proper electrical excitation types.

A retrospective study of focused ultrasound versus cryotherapy in treatment of cervical squamous intraepithelial lesions

PURPOSE

To compare the efficacy and safety of focused ultrasound (FUS) therapy and cryotherapy for cervical squamous intraepithelial lesion (SIL).

METHODS

In this retrospective study, data pertaining to women treated for cervical SIL with FUS therapy or cryotherapy at the Second Affiliated Hospital of Chongqing Medical University between 21 April 2018 and 31 August 2020 were obtained. The patients were followed up after 3-6 and 6-12 months. The proportions of women with no evidence of disease, recurrent disease, clearance of the human papillomavirus (HPV) and adverse effects or complications were determined.

RESULTS

Of the 250 women with complete data who were included in the study, 144 and 106 received FUS therapy and cryotherapy, respectively. Overall, FUS therapy was observed to be more effective than cryotherapy (91.7 vs. 79.2%, p = 0.005). Statistically significant differences were noted in the treatment efficacy for patients with low-grade SIL (LSIL) (92.3 vs. 80.2%, p = 0.011). However, there were no significant differences in the treatment efficacy for patients with high-grade SIL (HSIL) (88.9 vs. 75.0%, p = 0.390). The recurrence rates in patients with LSIL treated with FUS therapy or cryotherapy showed no significant differences at the 6-12-month follow-up (1.0 vs. 6.0%, p = 0.163). Furthermore, there was no recurrence in patients with HSIL, either in the FUS or cryotherapy group. FUS therapy and cryotherapy resulted in similar HPV clearance at the 3-6-month follow-up (77.1 vs. 64.8%, p = 0.057). No statistically significant differences were observed in the complication rates between the two groups (3.5 vs. 1.9%, p = 0.717).

CONCLUSION

The results of this study suggest that FUS therapy is superior to cryotherapy in the treatment of cervical LSIL.

In Situ Upregulating Heat Shock Protein 70 via Gastric Nano-Heaters for the Interference of Helicobacter pylori Infection

Taking inspiration from the mechanism of Helicobacter pylori infection can lead to innovative antibacterial ways to fight antibiotics resistance. Herein, a gastric nano-heater iron-cobalt alloy shielded with graphitic shells (FeCo@G) is developed to interfere with H. pylori infection under an alternating magnetic field. FeCo@G shows a high and stable specific loss power (SLP = 534.1 W g^-1) in the acidic environment and provides efficient magnetothermal stimulation in the stomach. Such stimulation upregulates the cytoprotective heat shock protein 70 (HSP70) in gastric epithelial cells, which antagonizes the infection of H. pylori. This finding is further supported by the transcriptomic analysis verifying the upregulation of HSP70 in the stomach. Moreover, the nano-heater shows a high inhibition rate of H. pylori in vivo with good biocompatibility; 95% of FeCo@G is excreted from the mouse's gastrointestinal tract within 12 h. In summary, FeCo@G allows magnetothermal therapy to be used in harsh gastric environments, providing an approach for the therapy against H. pylori.

Clinical application status and prospect of the combined anti-tumor strategy of ablation and immunotherapy

Image-guided tumor ablation eliminates tumor cells by physical or chemical stimulation, which shows less invasive and more precise in local tumor treatment. Tumor ablation provides a treatment option for medically inoperable patients. Currently, clinical ablation techniques are widely used in clinical practice, including cryoablation, radiofrequency ablation (RFA), and microwave ablation (MWA). Previous clinical studies indicated that ablation treatment activated immune responses besides killing tumor cells directly, such as short-term anti-tumor response, immunosuppression reduction, specific and non-specific immune enhancement, and the reduction or disappearance of distant tumor foci. However, tumor ablation transiently induced immune response. The combination of ablation and immunotherapy is expected to achieve better therapeutic results in clinical application. In this paper, we provided a summary of the principle, clinical application status, and immune effects of tumor ablation technologies for tumor treatment. Moreover, we discussed the clinical application of different combination of ablation techniques with immunotherapy and proposed possible solutions for the challenges encountered by combined therapy. It is hoped to provide a new idea and reference for the clinical application of combinate treatment of tumor ablation and immunotherapy.

The role of anti-tumor immunity of focused ultrasound for the malignancies: depended on the different ablation categories

Improving anti-tumor immunity has promising outcomes in eradicating malignant tumors. Tumor cells can escape from immune surveillance and killing; therefore, various strategies are continuously developing to inhibit immune escape. Focused ultrasound (FUS) has recently emerged to play an important role in immune modulation. After FUS therapy, various tumor antigens and related signals are released. The non-thermal effect of FUS strengthens the blood and lymph circulation, increases cell permeability, and helps in crossing the physical barrier like the blood-brain barrier and blood-tumor barrier. However, the different ablation of FUS is proposed to have a different anti-tumor immune effect. Therefore, we categorized the FUS ablation into thermal and non-thermal ablation and summarized possible anti-tumor immunity mechanisms.

Neoadjuvant Therapy for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is characterized by low resection and high postoperative recurrence rates, and conventional treatment strategies have failed to meet clinical needs. Neoadjuvant therapy (NAT) is widely employed in the routine management of several solid tumors because it increases resectability and reduces the rate of postoperative recurrence. However, a consensus has not been reached regarding the effects of NAT on HCC. As systemic therapy, particularly targeted therapy and immunotherapy, is given for HCC treatment, accumulating evidence shows that the “spring” of NAT for HCC is imminent. In the future, HCC researchers should focus on identifying biomarkers for treatment response, explore the mechanisms of resistance, and standardize the endpoints of NAT.

Hyperthermia combined with immune checkpoint inhibitor therapy: Synergistic sensitization and clinical outcomes

BACKGROUND

Within the field of oncotherapy, research interest regarding immunotherapy has risen to the point that it is now seen as a key application. However, inherent disadvantages of immune checkpoint inhibitors (ICIs), such as their low response rates and immune-related adverse events (irAEs), currently restrict their clinical application. Were these disadvantages to be overcome, more patients could derive prolonged benefits from ICIs. At present, many basic experiments and clinical studies using hyperthermia combined with ICI treatment (HIT) have been performed and shown the potential to address the above challenges. Therefore, this review extensively summarizes the knowledge and progress of HIT for analysis and discusses the effect and feasibility.

METHODS

In this review, we explored the PubMed and clinicaltrials.gov databases, with regard to the searching terms "immune checkpoint inhibitor, immunotherapy, hyperthermia, ablation, photothermal therapy".

RESULTS

By reviewing the literature, we analyzed how hyperthermia influences tumor immunology and improves the efficacy of ICI. Hyperthermia can trigger a series of multifactorial molecular cascade reactions between tumors and immunization and can significantly induce cytological modifications within the tumor microenvironment (TME). The pharmacological potency of ICIs can be enhanced greatly through the immunomodulatory amelioration of immunosuppression, and the activation of immunostimulation. Emerging clinical trials outcome regarding HIT have verified and enriched the theoretical foundation of synergistic sensitization.

CONCLUSION

HIT research is now starting to transition from preclinical studies to clinical investigations. Several HIT sensitization mechanisms have been reflected and demonstrated as significant survival benefits for patients through pioneering clinical trials. Further studies into the theoretical basis and practical standards of HIT, combined with larger-scale clinical studies involving more cancer types, will be necessary for the future.

Chemotherapy and Physical Therapeutics Modulate Antigens on Cancer Cells

Cancer cells possess specific properties, such as multidrug resistance or unlimited proliferation potential, due to the presence of specific proteins on their cell membranes. The release of proliferation-related proteins from the membrane can evoke a loss of adaptive ability in cancer cells and thus enhance the effects of anticancer therapy. The upregulation of cancer-specific membrane antigens results in a better outcome of immunotherapy. Moreover, cytotoxic T-cells may also become more effective when stimulated ex-vivo toward the anticancer response. Therefore, the modulation of membrane proteins may serve as an interesting attempt in anticancer therapy. The presence of membrane antigens relies on various physical factors such as temperature, exposure to radiation, or drugs. Therefore, changing the tumor microenvironment conditions may lead to cancer cells becoming sensitized to subsequent therapy. This paper focuses on the therapeutic approaches modulating membrane antigens and enzymes in anticancer therapy. It aims to analyze the possible methods for modulating the antigens, such as pharmacological treatment, electric field treatment, photodynamic reaction, treatment with magnetic field or X-ray radiation. Besides, an overview of the effects of chemotherapy and immunotherapy on the immunophenotype of cancer cells is presented. Finally, the authors review the clinical trials that involved the modulation of cell immunophenotype in anticancer therapy.

High intensity focused ultrasound for the treatment of solid tumors: a pilot study in canine cancer patients

PURPOSE

To investigate the safety, feasibility, and outcomes of High-Intensity Focused Ultrasound (HIFU) for the treatment of solid tumors in a spontaneous canine cancer model.

METHODS

Dogs diagnosed with subcutaneous solid tumors were recruited, staged and pretreatment biopsies were obtained. A single HIFU treatment was delivered to result in partial tumor ablation using a commercially available HIFU unit. Tumors were resected 3-6 days post HIFU and samples obtained for histopathology and immunohistochemistry. Total RNA was isolated from paired pre and post treated FFPE tumor samples, and quantitative gene expression analysis was performed using the nCounter Canine IO Panel.

RESULTS

A total of 20 dogs diagnosed with solid tumors were recruited and treated in the study. Tumors treated included Soft Tissue Sarcoma (n = 15), Mast Cell Tumor (n = 3), Osteosarcoma (n = 1), and Thyroid Carcinoma (n = 1). HIFU was well tolerated with only 1 dog experiencing a clinically significant adverse event. Pathology confirmed the presence of complete tissue ablation at the HIFU targeted site and immunohistochemistry indicated immune cell infiltration at the treated/untreated tumor border. Quantitative gene expression analysis indicated that 28 genes associated with T-cell activation were differentially expressed post-HIFU.

CONCLUSIONS

HIFU appears to be safe and feasible for the treatment of subcutaneous canine solid tumors, resulting in ablation of the targeted tissue. HIFU induced immunostimulatory changes, highlighting the canine cancer patient as an attractive model for studying the effects of focal ablation therapies on the tumor microenvironment.

Hepatocellular Carcinoma Intrinsic Cell Death Regulates Immune Response and Prognosis

Ablative and locoregional treatment options, such as radiofrequency, ethanol injection, microwave, and cryoablation, as well as irreversible electroporation, are effective therapies for early-stage hepatocellular carcinoma (HCC). Hepatocyte death caused by ablative procedures is known to increase the release of tumor-associated antigen, thus enhancing tumor immunogenicity. In addition, the heat ablative resection induces pyroptotic cell death accompanied by the release of several inflammatory factors and immune-related proteins, including damage-associated molecular patterns (DAMPs), heat shock proteins (HSPs), ficolin 3, ATP, and DNA/RNA, which potentiate the antitumoral immune response. Surgical approaches that enhance tumor necrosis and reduce hypoxia in the residual liver parenchyma have been shown to increase the disease-free survival rate by reducing the host’s immunosuppressive response. Scalpel devices and targeted surgical approach combined with immune-modulating drugs are an interesting and promising area to maximize therapeutic outcomes after HCC ablation.

Endoscopic Coregistered Ultrasound Imaging and Precision Histotripsy: Initial In Vivo Evaluation

Objective. Initial performance evaluation of a system for simultaneous high-resolution ultrasound imaging and focused mechanical submillimeter histotripsy ablation in rat brains. Impact Statement. This study used a novel combination of high-resolution imaging and histotripsy in an endoscopic form. This would provide neurosurgeons with unprecedented accuracy in targeting and executing nonthermal ablations in minimally invasive surgeries. Introduction. Histotripsy is a safe and effective nonthermal focused ablation technique. However, neurosurgical applications, such as brain tumor ablation, are difficult due to the presence of the skull. Current devices are too large to use in the minimally invasive approaches surgeons prefer. We have developed a combined imaging and histotripsy endoscope to provide neurosurgeons with a new tool for this application. Methods. The histotripsy component had a 10 mm diameter, operating at 6.3 MHz. Affixed within a cutout hole in its center was a 30 MHz ultrasound imaging array. This coregistered pair was used to ablate brain tissue of anesthetized rats while imaging. Histological sections were examined, and qualitative descriptions of ablations and basic shape descriptive statistics were generated. Results. Complete ablations with submillimeter area were produced in seconds, including with a moving device. Ablation progress could be monitored in real time using power Doppler imaging, and B-mode was effective for monitoring post-ablation bleeding. Collateral damage was minimal, with a 100 μm maximum distance of cellular damage from the ablation margin. Conclusion. The results demonstrate a promising hardware suite to enable precision ablations in endoscopic procedures or fundamental preclinical research in histotripsy, neuroscience, and cancer.

Combination of Radiofrequency Ablation With Resiquimod to Treat Hepatocellular Carcinoma Via Inflammation of Tumor Immune Microenvironment and Suppression of Angiogenesis

Background

Radiofrequency ablation (RFA) destroys tumors through hyperthermic injury, which induces the release of immunogenic intracellular substrates and damages associated molecular patterns (DAMPs) to evoke a systemic immune response, but its therapeutic effect is limited. This study aimed to combine RFA with an immunomodulator, resiquimod (R848), to enhance the RFA-induced antitumor immunity.

Methods

We performed RFA on subcutaneous tumors in immunocompetent mice and intraperitoneally injected R848 to observe the efficacy of the combination therapy. Our research investigated changes in the composition of tumor-infiltrating immune cells in primary and distant tumors by flow cytometry. Natural killer (NK) cell depletion experiment was applied to confirm the role of NK cell in the combination therapy. The expression levels of cytokines and chemokines were detected by real-time quantitative PCR. Immunohistochemical test was conducted to reveal tumor angiogenesis, tumor proliferation, and apoptosis after the different treatments.

Results and Conclusion

Compared with RFA or R848 monotherapy, the combination therapy significantly slowed the tumor growth, prolonged the survival time, and shrank the tumor-draining lymph nodes of tumor-bearing mice. The flow cytometry results showed that tumor-infiltrating immune cells, total T cells, the ratio of CD8⁺ T and NK cells to CD45⁺ cells, and functional NK cells were obviously increased after the combined treatment. Distal tumor growth was also suppressed, and the profile of tumor-infiltrating immune cells was remodeled, too. In addition, the additive effect of the combination therapy disappeared after NK cell depletion. Furthermore, immunohistochemical results verified that R848 inhibited tumor angiogenesis in murine liver cancer, and the combination therapy promoted tumor cell apoptosis. In conclusion, our data suggest that RFA combined with R848 stimulated a stronger antitumor immune response and effectively inhibited liver cancer progression in a NK cell-dependent manner. Meanwhile, we confirmed that R848 inhibited tumor angiogenesis and promoted apoptosis in murine liver cancer. Overall, this is a promising therapeutic strategy to improve the efficacy of RFA in the treatment of liver cancer and provides a novel option for combined thermal ablation and immunotherapy.

Multifunctional Theranostic Nanoparticles for Enhanced Tumor Targeted Imaging and Synergistic FUS/Chemotherapy on Murine 4T1 Breast Cancer Cell

Purpose

Triple negative breast cancer (TNBC) is challenging for effective remission due to its very aggressive, extremely metastatic and resistant to conventional chemotherapy. Herein, a multifunctional theranostic nanoparticle was fabricated to enhance tumor targeted imaging and promote focused ultrasound (FUS) ablation and chemotherapy and sonodynamic therapy (SDT). A multi-modal synergistic therapy can improve the therapeutic efficacy and prognosis of TNBC.

Methods

AS1411 aptamer modified PEG@PLGA nanoparticles encapsulated with perfluorohexane (PFH) and anti-cancer drug doxorubicin (DOX) were constructed (AS1411-DOX/PFH-PEG@PLGA) to enhance tumor targeted imaging to guide ablation and synergistic effect of FUS/chemotherapy. FUS was utilized to trigger the co-release of doxorubicin and simultaneously PFH phase transition and activate DOX for SDT effect. The physicochemical, phase-changeable imaging capability, biosafety of nanoparticles and multi-mode synergistic effects on growth of TNBC were thoroughly evaluated in vivo and in vitro.

Results

The synthesized AS1411-DOX/PFH-PEG@PLGA (A-DPPs) nanoparticles are uniformly round with an average diameter of 306.03 ± 5.35 nm and the zeta potential of −4.05 ± 0.13 mV, displaying high biosafety and FUS-responsive drug release in vitro and in vivo. AS1411 modified NPs specifically bind to 4T1 cells and elevate the ultrasound contrast agent (UCA) image contrast intensity via PFH phase-transition after FUS exposure. Moreover, the combined treatment of A-DPPs nanoparticles with FUS exhibited significantly higher apoptosis rate, stronger inhibitory effect on 4T1 cell invasion in vitro, induced more reactive oxygen species (ROS), and enhanced anti-tumor effect compared to a single therapy (p < 0.05). Additionally, the joint strategy resulted in more intense cavitation effect and larger ablated areas and reduced energy efficiency factor (EEF) both in vitro and in vivo.

Conclusion

The multifunctional AS1411-DOX/PFH-PEG@PLGA nanoparticles can perform as a marvelous synergistic agent for enhanced FUS/chemotherapy, promote real-time contrast enhanced US imaging and improve the therapeutic efficacy and prognosis of TNBC.

Ultrasound and microbubble-mediated drug delivery and immunotherapy

Ultrasound induces the oscillation and collapse of microbubbles such as those of an ultrasound contrast agent, where these behaviors generate mechanical and thermal effects on cells and tissues. These, in turn, induce biological responses in cells and tissues, such as cellular signaling, endocytosis, or cell death. These physiological effects have been used for therapeutic purposes. Most pharmaceutical agents need to pass through the blood vessel walls and reach the parenchyma cells to produce therapeutic effects in drug delivery. Therefore, the blood vessel walls act as an obstacle to drug delivery. The combination of ultrasound and microbubbles is a promising strategy to enhance vascular permeability, improving drug transport from blood to tissues. This combination has also been applied to gene and protein delivery, such as cytokines and antigens for immunotherapy. Immunotherapy, in particular, is an attractive technique for cancer treatment as it induces a cancer cell-specific response. However, sufficient anti-tumor effects have not been achieved with the conventional cancer immunotherapy. Recently, new therapies based on immunomodulation with immune checkpoint inhibitors have been reported. Immunomodulation can be regarded as a new strategy for cancer immunotherapy. It was also reported that mechanical and thermal effects induced by the combination of ultrasound and microbubbles could suppress tumor growth by promoting the cancer-immunity cycle via immunomodulation in the tumor microenvironment. In this review, we provide an overview of the application of ultrasound and microbubble combination for drug delivery and activation of the immune system in the microenvironment of tumor tissue.