Figure 2 - available via license: Creative Commons Attribution-NonCommercial 4.0 International
Content may be subject to copyright.
Mechanical focused ultrasound energy regimens for cancer immunotherapy. Left Column: Mechanical disruption using pulsed, high-pressure, focused ultrasound after intravenous injection of contrast agent microbubbles (top row: yellow dots evident in red blood vessels). Driving microbubbles into inertial cavitation by sweeping the ultrasound focus through the tumor volume disrupts cell membranes and mechanically injures tumor tissue. Due to the use of very low duty-cycles, this energy regimen is not typically associated with tumor heating. Right Column: Blood-brain and/or blood-tumor barrier opening for delivering systemically administered immunotherapeutic drugs (top row: green dots evident in red blood vessels) to the CNS using pulsed, low-pressure, focused ultrasound. Here, contrast agent microbubbles (top row: yellow dots evident in red blood vessels), which are i.v. injected with the immunotherapeutic drug, stably oscillate in the FUS field. Stable oscillations open the BBB/BTB, permitting targeted immunotherapeutic drug deliver to treated CNS tissue (bottom row; green dots).
Source publication
Immunotherapy is rapidly emerging as the cornerstone for the treatment of several forms of metastatic cancer, as well as for a host of other pathologies. Meanwhile, several new high-profile studies have uncovered remarkable linkages between the central nervous and immune systems. With these recent developments, harnessing the immune system for the...
Similar publications
The blood-brain barrier (BBB) has long limited therapeutic access to brain tumor and peritumoral tissue. In animals, MR-guided focused ultrasound (MRgFUS) with intravenously injected microbubbles can temporarily and repeatedly disrupt the BBB in a targeted fashion, without open surgery. Our objective is to demonstrate safety and feasibility of MRgF...
Focused ultrasound (FUS) exposure with microbubbles can transiently open the blood-brain barrier (BBB) to deliver therapeutic molecules into CNS tissues. However, delivered molecular distribution/concentration at the target need to be controlled. Dynamic Contrast-Enhanced Magnetic-Resonance Imaging (DCE-MRI) is a well-established protocol for monit...
Brain diseases including neurological disorders and tumors remain under treated due to the challenge to access the brain, and blood-brain barrier (BBB) restricting drug delivery which, also profoundly limits the development of pharmacological treatment. Focused ultrasound (FUS) with microbubbles is the sole method to open the BBB noninvasively, loc...
Rationale: Focused ultrasound (FUS), in conjunction with circulating microbubbles (MBs), can be used to transiently increase the permeability of the blood-brain barrier (BBB) in a targeted manner, allowing therapeutic agents to enter the brain from systemic circulation. While promising preclinical work has paved the way for the initiation of 3 huma...
Citations
... Hayashi et al. further reported that the degenerative changes associated with RT were limited from the histology sample of a DMG patient who received hypofractionated RT [42]. From our histological analysis, the addition of FUS did not exacerbate inflammation but increased mononuclear cell infiltration, which is unsurprising given that both RT and FUS are known to have immunomodulatory effects in the CNS [43,44]. Although we did not perform a further assay to confirm the specific cell type of infiltration in non-tumor-bearing animals, our group recently reported that FUS-mediated BBBO increases microglia and CNS-associated macrophage in the brain [29]. ...
Background
Diffuse midline glioma (DMG) is a pediatric tumor with dismal prognosis. Systemic strategies have been unsuccessful and radiotherapy (RT) remains the standard-of-care. A central impediment to treatment is the blood–brain barrier (BBB), which precludes drug delivery to the central nervous system (CNS). Focused ultrasound (FUS) with microbubbles can transiently and non-invasively disrupt the BBB to enhance drug delivery. This study aimed to determine the feasibility of brainstem FUS in combination with clinical doses of RT. We hypothesized that FUS-mediated BBB-opening (BBBO) is safe and feasible with 39 Gy RT.
Methods
To establish a safety timeline, we administered FUS to the brainstem of non-tumor bearing mice concurrent with or adjuvant to RT; our findings were validated in a syngeneic brainstem murine model of DMG receiving repeated sonication concurrent with RT. The brainstems of male B6 (Cg)-Tyrc-2J/J albino mice were intracranially injected with mouse DMG cells (PDGFB ⁺ , H3.3K27M, p53 −/− ). A clinical RT dose of 39 Gy in 13 fractions (39 Gy/13fx) was delivered using the Small Animal Radiation Research Platform (SARRP) or XRAD-320 irradiator. FUS was administered via a 0.5 MHz transducer, with BBBO and tumor volume monitored by magnetic resonance imaging (MRI).
Results
FUS-mediated BBBO did not affect cardiorespiratory rate, motor function, or tissue integrity in non-tumor bearing mice receiving RT. Tumor-bearing mice tolerated repeated brainstem BBBO concurrent with RT. 39 Gy/13fx offered local control, though disease progression occurred 3–4 weeks post-RT.
Conclusion
Repeated FUS-mediated BBBO is safe and feasible concurrent with RT. In our syngeneic DMG murine model, progression occurs, serving as an ideal model for future combination testing with RT and FUS-mediated drug delivery.
... Therefore, safe and effective improvement of tumor vessel normalization and enhancement of the concentration and efficacy of VEGF targeted therapeutics are expected to become an important part of anti -antigenic therapy (Heath and Bicknell, 2009). Ultrasound combined with microbubbles to enhance the treatment of anti-VEGF and anti-VEGF receptor antibody is helpful for immunosuppression in the tumor microenvironment (Curley et al., 2017). Based on previous studies, ultrasound combined with microbubbles has the ability to improve the composition and integrity of tumor vascular system, improve drug permeability and normalize blood vessels, which is one of the main clinical strategies to improve the drug delivery and treatment effects of tumor TME (Kooiman et al., 2020). ...
The tumor microenvironment (TME) plays an important role in dynamically regulating the progress of cancer and influencing the therapeutic results. Targeting the tumor microenvironment is a promising cancer treatment method in recent years. The importance of tumor immune microenvironment regulation by ultrasound combined with microbubbles is now widely recognized. Ultrasound and microbubbles work together to induce antigen release of tumor cell through mechanical or thermal effects, promoting antigen presentation and T cells’ recognition and killing of tumor cells, and improve tumor immunosuppression microenvironment, which will be a breakthrough in improving traditional treatment problems such as immune checkpoint blocking (ICB) and himeric antigen receptor (CAR)-T cell therapy. In order to improve the therapeutic effect and immune regulation of TME targeted tumor therapy, it is necessary to develop and optimize the application system of microbubble ultrasound for organs or diseases. Therefore, the combination of ultrasound and microbubbles in the field of TME will continue to focus on developing more effective strategies to regulate the immunosuppression mechanisms, so as to activate anti-tumor immunity and/or improve the efficacy of immune-targeted drugs, At present, the potential value of ultrasound combined with microbubbles in TME targeted therapy tumor microenvironment targeted therapy has great potential, which has been confirmed in the experimental research and application of breast cancer, colon cancer, pancreatic cancer and prostate cancer, which provides a new alternative idea for clinical tumor treatment. This article reviews the research progress of ultrasound combined with microbubbles in the treatment of tumors and their application in the tumor microenvironment.
... By identifying gene expression patterns, epigenetic modifications, and metabolic signatures associated with neuroinflammation, a deeper understanding of new and novel pathways may be revealed. As such, AI-powered predictive models can help assess treatment responses and prognosis, and support the categorization of neuroinflammatory endophenotypes in brain trauma (48)(49)(50). Further, neuromodulation techniques or non-invasive approaches including focused ultrasound, are being explored to directly influence the activity of neuroimmune cells within the CNS (51). These non-invasive approaches have the potential to modulate neuroinflammatory responses, by facilitating the delivery of immunotherapeutic agents into the brain and exerting direct immune-related effects (52,53). ...
Acquired traumatic central nervous system (CNS) injuries, including traumatic brain injury (TBI) and spinal cord injury (SCI), are devastating conditions with limited treatment options. Neuroinflammation plays a pivotal role in secondary damage, making it a prime target for therapeutic intervention. Emerging therapeutic strategies are designed to modulate the inflammatory response, ultimately promoting neuroprotection and neuroregeneration. The use of anti-inflammatory agents has yielded limited support in improving outcomes in patients, creating a critical need to re-envision novel approaches to both quell deleterious inflammatory processes and upend the progressive cycle of neurotoxic inflammation. This demands a comprehensive exploration of individual, age, and sex differences, including the use of advanced imaging techniques, multi-omic profiling, and the expansion of translational studies from rodents to humans. Moreover, a holistic approach that combines pharmacological intervention with multidisciplinary neurorehabilitation is crucial and must include both acute and long-term care for the physical, cognitive, and emotional aspects of recovery. Ongoing research into neuroinflammatory biomarkers could revolutionize our ability to predict, diagnose, and monitor the inflammatory response in real time, allowing for timely adjustments in treatment regimens and facilitating a more precise evaluation of therapeutic efficacy. The management of neuroinflammation in acquired traumatic CNS injuries necessitates a paradigm shift in our approach that includes combining multiple therapeutic modalities and fostering a more comprehensive understanding of the intricate neuroinflammatory processes at play.
... Since immunity plays such a key role in the progression of tumors, immunotherapy has made tremendous progress as the fourth major tumor treatment modality after surgery, chemotherapy and radiotherapy [3]. Stimulation of the immune system has shown some promise in the treatment of tumors as well as immune activation may lead to the destruction and clearance of tumor cells or protein aggregates [4]. Immunotherapies such as cancer vaccination [5], cytotoxic T lymphocyteassociated antigen 4, checkpoint inhibitor immunotherapy [6] or chimeric antigen receptor T-cell immunotherapy [7] have been shown to mobilize the systemic immune system to fight tumors. ...
Tumor immunotherapy is booming around the world. However, strategies to activate the immune system and alleviate the immunosuppression still need to be refined. Here, we demonstrate for the first time that low-intensity pulsed ultrasound (LIPUS, spatial average time average intensity (Isata) is 200 mW/cm², frequency is 0.3 MHz, repetition frequency is 1 kHz, and duty cycle is 20%) triggers the immune system and further reverses the immunosuppressive state in the mouse models of breast cancer by irradiating the spleen of mice. LIPUS inhibited tumor growth and extended survival in mice with 4 T-1 tumors. Further studies had previously shown that LIPUS enhanced the activation of CD4⁺ and CD8⁺ T cells in the spleen and led to significant changes in cytokines, as well as induced upregulation of mRNA levels involved in multiple immune regulatory pathways in the spleen. In addition, LIPUS promoted tumor-infiltrating lymphocyte accumulation and CD8⁺ T cell activation and improved the dynamics of cytokines/chemokines in the tumor microenvironment, resulting in a reversal of the immunosuppressive state of the tumor microenvironment. These results suggest a novel approach to activate the immune response by irradiating the spleen with LIPUS.
Supplementary Information
The online version contains supplementary material available at 10.1007/s00262-023-03613-1.
... For detailed reviews refer to. [30][31][32] (1) Inducing BBB permeability ( Figure 1A). One of the best-studied approaches is focused ultrasound (FUS). ...
... 61 Figure 1. Strategies to increase antibody delivery to the brain across the BBB (A) Permeabilization: (1) Focused ultrasound (FUS) induces a steady oscillation of intravenously administered microbubbles, which transiently permeabilize the BBB (reviewed in 30 ; 2) Pharmacological reduction of BBB function, e.g., using potassium channel agonists to increase brain uptake of an anti-Her-2 Ab. 36 (3) Osmotic permeabilization of the BBB showed positive effects on the delivery of therapeutic antibodies. 37 (B) Charge-optimization: During adsorption-mediated transcytosis (AMT), positively charged molecules are endocytosed and transported through the BBB. ...
Treating brain diseases requires therapeutics to pass the blood-brain barrier (BBB) which is nearly impermeable for large biologics such as antibodies. Several methods now facilitate crossing or circumventing the BBB for antibody therapeutics. Some of these exploit receptor-mediated transcytosis, others use direct delivery bypassing the BBB. However, successful delivery into the brain does not preclude exit back to the systemic circulation. Various mechanisms are implicated in the active and passive export of antibodies from the central nervous system. Here we review findings on active export via transcytosis of therapeutic antibodies - in particular, the role of the neonatal Fc receptor (FcRn) - and discuss a possible contribution of passive efflux pathways such as lymphatic and perivascular drainage. We point out open questions and how to address these experimentally. In addition, we suggest how emerging findings could aid the design of the next generation of therapeutic antibodies for neurologic diseases.
... High-intensity FUS (HIFU), where the delivered total energy intensity is typically greater than 1000 Watts/cm 2 , has already been applied in clinical trials for various solid cancers. HIFU primarily acts by inducing thermal coagulative necrosis, which is associated with non-specific tissue destruction and inflammation, and the induction of cellular stress responses [132][133][134][135][136]. FUS has been shown to promote a T-cell-mediated anti-tumor response, characterized by decreased tumor growth and proliferation [137]; increased infiltration of activated, tumor-specific effector CD4+ and CD8+ T-cells; and increased infiltration of inflammatory macrophages [138,139]. ...
... Leads to non-specific tissue destruction and inflammation (HIFU) or to mild hyperthermia with increased heat shock protein expression and induction of cellular stress responses (LOFU); combination with nanovesicles and microbubbles leads to increased cell membrane permeability and improved drug delivery [132][133][134][135][136]140] Sonodynamic therapy Combination therapy of FUS with a sensitizing agent; generates ROS and promotes tumor cell damage, apoptosis, and necrosis [145] Magnetic hyperthermia Nanovesicle-mediated, localized hyperthermia induces necrotic ICD; increases expression of chemoattractant and TLR pathway markers [147,148] Nanosecond pulsed electric fields Electric pulses enhance membrane permeability and trigger cellular stress responses (autophagy, necrosis, and apoptosis) [149,150] Plasma-derived oxidants Increases presence of ROS/RNS [151,152] ...
Advanced melanoma is an aggressive form of skin cancer characterized by low survival rates. Less than 50% of advanced melanoma patients respond to current therapies, and of those patients that do respond, many present with tumor recurrence due to resistance. The immunosuppressive tumor-immune microenvironment (TIME) remains a major obstacle in melanoma therapy. Adjuvant treatment modalities that enhance anti-tumor immune cell function are associated with improved patient response. One potential mechanism to stimulate the anti-tumor immune response is by inducing immunogenic cell death (ICD) in tumors. ICD leads to the release of damage-associated molecular patterns within the TIME, subsequently promoting antigen presentation and anti-tumor immunity. This review summarizes relevant concepts and mechanisms underlying ICD and introduces the potential of non-ablative low-intensity focused ultrasound (LOFU) as an immune-priming therapy that can be combined with ICD-inducing focal ablative therapies to promote an anti-melanoma immune response.
... The therapeutic effectiveness and cost of the immunotherapy remain questionable as patients treated with the abovementioned substances may have severe side effects with substances being poorly hydrophilic and easily degraded in the blood circulation [127][128][129]. In past few years, it has been found that ultrasound can be used to stimulate an anti-tumor immune response [130][131][132][133]. Ultrasound on its own can regulate the immune response by thermally ablating the tumors however, when used alongside immunotherapeutics it helps in increasing the therapeutic efficacy of immunotherapy [134][135][136]. Using ultrasound can help in the precise ablation of tumors and reduce the required drug dosage needed to treat cancer thus resulting in minimal side effects [137]. ...
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.
... Another proposed mode of action of vascular shutdown for antitumor therapy is to trigger an antitumor immune response following endothelial damages. Most preclinical and clinical literature suggests that ultrasound microbubbles destruction may trigger anti-tumor immunity by induction of specific inflammation, modulating immunosuppressive cytokine expression, releasing endogenous danger signals such as heat shock proteins and tumor antigens which can stimulate leukocyte infiltration and activation mostly through increased vascular permeability [105][106][107]. When low intensity microbubbles destruction was applied to a subcutaneous model of melanoma, there was increased infiltration of HIF1A+ (hypoxia inducible factor 1A+) cells indicative of necrosis and increased CD45+/CD3+ T-cells into the tumors [108]. ...
... Moreover, analyses of the immune infiltrate were conducted at different time points in these different studies, and the dynamic aspect of an immune-modulation following ultrasound-microbubbles treatment is yet unknown. These reports may also suggest that the exact exposure conditions and associated parameters are of utmost importance in the resulting immunomodulation, as has also been observed with ablative therapeutic ultrasound modalities [105]. ...
Ultrasound-triggered microbubbles destruction leading to vascular shutdown have resulted in preclinical studies in tumor growth delay or inhibition, lesion formation, radio-sensitization and modulation of the immune micro-environment. Antivascular ultrasound aims to be developed as a focal, targeted, non-invasive, mechanical and non-thermal treatment, alone or in combination with other treatments, and this review positions these treatments among the wider therapeutic ultrasound domain. Antivascular effects have been reported for a wide range of ultrasound exposure conditions, and evidence points to a prominent role of cavitation as the main mechanism. At relatively low peak negative acoustic pressure, predominantly non-inertial cavitation is most likely induced, while higher peak negative pressures lead to inertial cavitation and bubbles collapse. Resulting bioeffects start with inflammation and/or loose opening of the endothelial lining of the vessel. The latter causes vascular access of tissue factor, leading to platelet aggregation, and consequent clotting. Alternatively, endothelium damage exposes subendothelial collagen layer, leading to rapid adhesion and aggregation of platelets and clotting. In a pilot clinical trial, a prevalence of tumor response was observed in patients receiving ultrasound-triggered microbubble destruction along with transarterial radioembolization. Two ongoing clinical trials are assessing the effectiveness of ultrasound-stimulated microbubble treatment to enhance radiation effects in cancer patients. Clinical translation of antivascular ultrasound/microbubble approach may thus be forthcoming.
... Unfortunately, the therapeutic efficacy of chemotherapeutic agents is limited due to the BBB [5,6,9,10]. Treatment with therapeutic molecules is largely limited by the molecular size of the drugs (e.g., doxorubicin ∼540 Da and bevacizumab 149 kDa) [11]. In contrast, temozolomide (TMZ), a lipophilic molecule with a molecular size of 194 Da, is one of few chemotherapeutic agents that can cross the BBB and treat CNS tumors [12]. ...
... To overcome these limitations, intra-arterial infusion of mannitol, direct injection, and convection enhanced delivery may be used. However, these approaches are invasive and non-targeted [11]. This poses a therapeutic dilemma as the efficacy of treatment does not outweigh the systemic effects. ...
... While most pre-clinical research involving MRgFUS has focused on LIFU, recent studies have shown that HIFU can serve as a direct therapeutic agent through thermoablation [11]. One study analyzed RNA and protein expression changes in MRgFUS-induced BBB hyperpermeability using pulsed FUS with MB parameters. ...
Malignant brain tumors are the leading cause of cancer-related death in children and remain a significant cause of morbidity and mortality throughout all demographics. Central nervous system (CNS) tumors are classically treated with surgical resection and radiotherapy in addition to adjuvant chemotherapy. However, the therapeutic efficacy of chemotherapeutic agents is limited due to the blood-brain barrier (BBB). Magnetic resonance guided focused ultrasound (MRgFUS) is a new and promising intervention for CNS tumors, which has shown success in preclinical trials. High-intensity focused ultrasound (HIFU) has the capacity to serve as a direct therapeutic agent in the form of thermoablation and mechanical destruction of the tumor. Low-intensity focused ultrasound (LIFU) has been shown to disrupt the BBB and enhance the uptake of therapeutic agents in the brain and CNS. The authors present a review of MRgFUS in the treatment of CNS tumors. This treatment method has shown promising results in preclinical trials including minimal adverse effects, increased infiltration of the therapeutic agents into the CNS, decreased tumor progression, and improved survival rates.
... When the ultrasound beam is focused, these physical changes and functions are localized in the focal region and can lead to a local increase in the vascular permeability for up to 24 h post sonication (Hynynen et al., 2001;Aryal et al., 2014;Meairs, 2015), providing a window for spatio-temporal targeted drug delivery (Aryal et al., 2014). These findings indicate the feasibility of US-responsive MBs to deliver various types of anti-cancer agents, including chemotherapeutics, antibodies, nanoparticle drug conjugates, and viruses (Curley et al., 2017;Schoen et al., 2022). Recently, the impacts of FUS-MB delivery on the immune system and TME in solid tumors are under investigation. ...
In the last decade, immune checkpoint blockade (ICB) has revolutionized the standard of treatment for solid tumors. Despite success in several immunogenic tumor types evidenced by improved survival, ICB remains largely unresponsive, especially in “cold tumors” with poor lymphocyte infiltration. In addition, side effects such as immune-related adverse events (irAEs) are also obstacles for the clinical translation of ICB. Recent studies have shown that focused ultrasound (FUS), a non-invasive technology proven to be effective and safe for tumor treatment in clinical settings, could boost the therapeutic effect of ICB while alleviating the potential side effects. Most importantly, the application of FUS to ultrasound-sensitive small particles, such as microbubbles (MBs) or nanoparticles (NPs), allows for precise delivery and release of genetic materials, catalysts and chemotherapeutic agents to tumor sites, thus enhancing the anti-tumor effects of ICB while minimizing toxicity. In this review, we provide an updated overview of the progress made in recent years concerning ICB therapy assisted by FUS-controlled small-molecule delivery systems. We highlight the value of different FUS-augmented small-molecules delivery systems to ICB and describe the synergetic effects and underlying mechanisms of these combination strategies. Furthermore, we discuss the limitations of the current strategies and the possible ways that FUS-mediated small-molecule delivery systems could boost novel personalized ICB treatments for solid tumors.
