Focused Ultrasound Strategies for Brain Tumor Therapy

Abstract BACKGROUND A key challenge in the medical treatment of brain tumors is the limited penetration of most chemotherapeutic agents across the blood–brain barrier (BBB) into the tumor and the infiltrative margin around the tumor. Magnetic resonance-guided focused ultrasound (MRgFUS) is a promising tool to enhance the delivery of chemotherapeutic agents into brain tumors. OBJECTIVE To review the mechanism of FUS, preclinical evidence, and clinical studies that used low-frequency FUS for a BBB opening in gliomas. METHODS Literature review. RESULTS The potential of externally delivered low-intensity ultrasound for a temporally and spatially precise and predictable disruption of the BBB has been investigated for over a decade, yielding extensive preclinical literature demonstrating that FUS can disrupt the BBB in a spatially targeted and temporally reversible manner. Studies in animal models documented that FUS enhanced the delivery of numerous chemotherapeutic and investigational agents across the BBB and into brain tumors, including temozolomide, bevacizumab, 1,3-bis (2-chloroethyl)-1-nitrosourea, doxorubicin, viral vectors, and cells. Chemotherapeutic interventions combined with FUS slowed tumor progression and improved animal survival. Recent advances of MRgFUS systems allow precise, temporally and spatially controllable, and safe transcranial delivery of ultrasound energy. Initial clinical evidence in glioma patients has shown the efficacy of MRgFUS in disrupting the BBB, as demonstrated by an enhanced gadolinium penetration. CONCLUSION Thus far, a temporary disruption of the BBB followed by the administration of chemotherapy has been both feasible and safe. Further studies are needed to determine the actual drug delivery, including the drug distribution at a tissue-level scale, as well as effects on tumor growth and patient prognosis.

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A review of potential applications of MR-guided focused ultrasound for targeting brain tumor therapy

Neurosurgical FOCUS ◽

10.3171/2017.11.focus17620 ◽

2018 ◽

Vol 44 (2) ◽

pp. E10 ◽

Cited By ~ 20

Author(s):

Layton Lamsam ◽

Eli Johnson ◽

Ian D. Connolly ◽

Max Wintermark ◽

Melanie Hayden Gephart

Keyword(s):

Drug Delivery ◽

Brain Tumor ◽

Brain Tumors ◽

Focused Ultrasound ◽

Tumor Therapy ◽

Survival Times ◽

Potential Applications ◽

Animal Tumor ◽

Antitumor Chemotherapy ◽

Systemic Drug Delivery

Magnetic resonance–guided focused ultrasound (MRgFUS) has been used extensively to ablate brain tissue in movement disorders, such as essential tremor. At a lower energy, MRgFUS can disrupt the blood-brain barrier (BBB) to allow passage of drugs. This focal disruption of the BBB can target systemic medications to specific portions of the brain, such as for brain tumors. Current methods to bypass the BBB are invasive, as the BBB is relatively impermeable to systemically delivered antineoplastic agents. Multiple healthy and brain tumor animal models have suggested that MRgFUS disrupts the BBB and focally increases the concentration of systemically delivered antitumor chemotherapy, immunotherapy, and gene therapy. In animal tumor models, combining MRgFUS with systemic drug delivery increases median survival times and delays tumor progression. Liposomes, modified microbubbles, and magnetic nanoparticles, combined with MRgFUS, more effectively deliver chemotherapy to brain tumors. MRgFUS has great potential to enhance brain tumor drug delivery, while limiting treatment toxicity to the healthy brain.

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Novel Advances in Drug Delivery to Brain Cancer

Technology in Cancer Research & Treatment ◽

10.1177/153303460500400409 ◽

2005 ◽

Vol 4 (4) ◽

pp. 417-428 ◽

Cited By ~ 15

Author(s):

Maciej S. Lesniak

Keyword(s):

Drug Delivery ◽

Brain Tumors ◽

Tumor Therapy ◽

Chemotherapeutic Agents ◽

Controlled Delivery ◽

Local Drug Delivery ◽

Delivery Methods ◽

Malignant Brain Tumors ◽

Direct Exposure ◽

The Brain

The therapy of brain tumors has been limited by a lack of effective methods of drug delivery to the brain. Systemic administration is often associated with toxic side effects and ultimately fails to achieve therapeutic concentrations within a tumor. An attractive strategy that has gained importance in brain tumor therapy has relied on local and controlled delivery of chemotherapeutic agents by biodegradable polymers. This technique allows direct exposure of tumor cells to a therapeutic agent for a prolonged period of time and has been shown to prolong the survival of patients with malignant brain tumors. The use of polymers for local drug delivery greatly expands the spectrum of drugs available for the treatment of malignant brain tumors. This review discusses the rationale for local drug delivery, describes the development of currently available polymer-based therapeutic agents, and highlights examples of promising non-polymer based drug delivery methods for use in the treatment of malignant brain tumors.

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BIOM-44. PRE-SURGICAL ADVANCED MRI IS USEFUL FOR FORECASTING DRUG DISTRIBUTION IN BRAIN TUMORS

Neuro-Oncology ◽

10.1093/neuonc/noab196.075 ◽

2021 ◽

Vol 23 (Supplement_6) ◽

pp. vi20-vi21

Author(s):

Pamela Jackson ◽

Minjee Kim ◽

Andrea Hawkins-Daarud ◽

Kyle Singleton ◽

Afroz Mohammad ◽

...

Keyword(s):

Brain Tumors ◽

Diffusion Tensor ◽

Quantitative Imaging ◽

Drug Distribution ◽

Non Invasive ◽

Promising Tool ◽

Contrast Enhanced ◽

Multiple Blood ◽

Mri Sequences ◽

Magnetic Resonance Imaging Mri

Abstract Choosing effective chemotherapies for intravenous delivery to brain tumors is challenging, especially given the protective nature of the blood brain barrier (BBB). Connecting drug distribution to non-invasive, pre-surgical magnetic resonance imaging (MRI) could allow for predictive insight into drug distribution. In a previous study, we found that T2Gd images were predictive of a low BBB penetrant drug (Cefazolin), and FLAIR images were predictive of a high BBB penetrant drug (Levetiracetam). While these results are promising, we further seek to explore how advanced MRI sequences might inform image-based models of drug distribution. Prior to surgery, we acquired advanced dynamic contrast enhanced (DCE) and diffusion weighted imaging (DWI) MRI sequences for eight brain tumor patients (7 gliomas and 1 metastatic adenocarcinoma) in addition to the anatomic MRIs. All resulting quantitative maps and acquired images were co-registered. Prior to incision, patients received injections of cefazolin and levetiracetam. Next, multiple blood samples and biopsies were collected during surgery. Biopsies and plasma samples were analyzed for drug concentration using liquid chromatography mass spectrometry (LCMS), and biopsy drug levels were reported as Brain-Plasma Ratio (BPR). Mean image intensity was extracted from a 15x15 voxel window surrounding the biopsy location. We performed linear regression analyses to determine which combination of images were predictive of BPR. We found that considering quantitative imaging improved our initial ability to predict BPR for both drugs. For cefazolin, the third diffusion tensor eigenvalue (L3) map was significantly correlated with BPR (p< 0.001, R2= 0.36). For levetiracetam, the best model consisted of a combination of images and maps with the L3 map and the isotropic diffusion map (P) being the most influential (p= 0.001, R2= 0.63). Advanced MRI-based modeling is a promising tool for forecasting drug distribution in brain tumors and could be of great importance for understanding efficacy and selecting therapeutic strategies.

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PRDM14: A Potential Target for Cancer Therapy

Current Cancer Drug Targets ◽

10.2174/1568009618666180430143055 ◽

2018 ◽

Vol 18 (10) ◽

pp. 945-956 ◽

Cited By ~ 3

Author(s):

Mengting Ou ◽

Shun Li ◽

Liling Tang

Keyword(s):

Cancer Cells ◽

Tumor Therapy ◽

Embryonic Stem ◽

Molecular Target ◽

Chemotherapeutic Agents ◽

Epigenetic Mechanisms ◽

Tumor Treatment ◽

Precise Understanding ◽

Pr Domain ◽

Low Expression

PRDM14 belongs to the PR domain-containing (PRDM) family. Although a precise understanding focused on the function of PRDM14 to maintain stemness and pluripotency in embryonic stem cells via epigenetic mechanisms, growing experimental evidence has been linked PRDM14 to human cancers. In adults, PRDM14 has low expression in human tissues. Aberrant PRDM14 expression is connected with various malignant histological types and solid cancers, where PRDM14 can act as a driver of oncogenic processes. Overexpression of RPDM14 enhanced cancer cells growth and reduced cancer cells sensitive to chemotherapeutic agents. Reducing the expression of PRDM14 in cancer cells can enhance the therapeutic sensitivity of drugs to cancer cells, suggesting that aberrant PRDM14 may have a carcinogenic characteristic in tumor therapy and as a new molecular target. This review summarizes the structure and oncogenic properties of PRDM14 in different malignancies and suggests that PRDM14 may be a potential therapeutic molecular target for tumor treatment.

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A Review of Electroporation-based Antitumor Skin Therapies and Investigation of Betulinic Acid-loaded Ointment

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520617666171113120255 ◽

2018 ◽

Vol 18 (5) ◽

pp. 693-701

Author(s):

Monika Bakonyi ◽

Szilvia Berko ◽

Gabor Eros ◽

Gabor Varju ◽

Cristina A. Dehelean ◽

...

Keyword(s):

Betulinic Acid ◽

High Efficiency ◽

Antitumor Agents ◽

Ex Vivo ◽

Mouse Skin ◽

Chemotherapeutic Agents ◽

Hairless Mouse ◽

Promising Tool ◽

Acid Formulation ◽

Invasive Method

Background: Electrochemotherapy is a novel treatment for cutaneous and subcutaneous tumors utilizing the combination of electroporation and chemotherapeutic agents. Since tumors have an increasing incidence nowadays as a result of environmental and genetic factors, electrochemotherapy could be a promising treatment for cancer patients. Objective: The aim of this article is to summarize the novel knowledge about the use of electroporation for antitumor treatments and to present a new application of electrochemotherapy with a well-known plant derived antitumor drug betulinic acid. For the review we have searched the databases of scientific and medical research to collect the available publications about the use of electrochemotherapy in the treatment of various types of cancer. Method: By the utilization of the available knowledge, we investigated the effect of electroporation on the penetration of a topically applied betulinic acid formulation into the skin by ex vivo Raman spectroscopy on hairless mouse skin. Results: Raman measurements have demonstrated that the penetration depth of betulinic acid can be remarkably ameliorated by the use of electroporation, so this protocol can be a possibility for the treatment of deeper localized cancer nodules. Furthermore, it proved the influence of various treatment times, since they caused different spatial distributions of the drug in the skin. Conclusion: The review demonstrates that electrochemotherapy is a promising tool to treat different kinds of tumors with high efficiency and with only a few moderate adverse effects. Moreover, it presents a non-invasive method to enhance the penetration of antitumor agents, which can offer novel prospects for antitumor therapies.

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Focused ultrasound in neuro-oncology: the role of the Focused Ultrasound Foundation in driving adoption and innovation

Journal of Neuro-Oncology ◽

10.1007/s11060-021-03808-5 ◽

2021 ◽

Author(s):

Emily C. Whipple ◽

Camille A. Favero ◽

Neal F. Kassell

Keyword(s):

Drug Delivery ◽

Brain Tumors ◽

Focused Ultrasound ◽

Clinical Evidence ◽

Neurological Injury ◽

High Concentration ◽

Potential Applications ◽

Tumor Agent

Abstract Introduction Intra-arterial (lA) delivery of therapeutic agents across the blood-brain barrier (BBB) is an evolving strategy which enables the distribution of high concentration therapeutics through a targeted vascular territory, while potentially limiting systemic toxicity. Studies have demonstrated lA methods to be safe and efficacious for a variety of therapeutics. However, further characterization of the clinical efficacy of lA therapy for the treatment of brain tumors and refinement of its potential applications are necessary. Methods We have reviewed the preclinical and clinical evidence supporting superselective intraarterial cerebral infusion (SSJACI) with BBB disruption for the treatment of brain tumors. In addition, we review ongoing clinical trials expanding the applicability and investigating the efficacy of lA therapy for the treatment of brain tumors. Results Trends in recent studies have embraced the use of SSIACI and less neurotoxic chemotherapies. The majority of trials continue to use mannitol as the preferred method of hyperosmolar BBB disruption. Recent preclinical and preliminary human investigations into the lA delivery of Bevacizumab have demonstrated its safety and efficacy as an anti-tumor agent both alone and in combination with chemotherapy. Conclusion lA drug delivery may significantly affect the way treatment are delivered to patients with brain tumors, and in particular GBM. With refinement and standardization of the techniques of lA drug delivery, improved drug selection and formulations, and the development of methods to minimize treatment-related neurological injury, lA therapy may offer significant benefits for the treatment of brain tumors.

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Systemic AAV6-synapsin-GFP administration results in lower liver biodistribution, compared to AAV1&2 and AAV9, with neuronal expression following ultrasound-mediated brain delivery

Scientific Reports ◽

10.1038/s41598-021-81046-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Danielle Weber-Adrian ◽

Rikke Hahn Kofoed ◽

Joseph Silburt ◽

Zeinab Noroozian ◽

Kairavi Shah ◽

...

Keyword(s):

Gene Delivery ◽

Intravenous Injection ◽

Viral Vectors ◽

Focused Ultrasound ◽

Fluorescent Protein ◽

Gfp Expression ◽

Peripheral Organs ◽

Neuronal Expression ◽

Green Fluorescent ◽

The Brain

AbstractNon-surgical gene delivery to the brain can be achieved following intravenous injection of viral vectors coupled with transcranial MRI-guided focused ultrasound (MRIgFUS) to temporarily and locally permeabilize the blood–brain barrier. Vector and promoter selection can provide neuronal expression in the brain, while limiting biodistribution and expression in peripheral organs. To date, the biodistribution of adeno-associated viruses (AAVs) within peripheral organs had not been quantified following intravenous injection and MRIgFUS delivery to the brain. We evaluated the quantity of viral DNA from the serotypes AAV9, AAV6, and a mosaic AAV1&2, expressing green fluorescent protein (GFP) under the neuron-specific synapsin promoter (syn). AAVs were administered intravenously during MRIgFUS targeting to the striatum and hippocampus in mice. The syn promoter led to undetectable levels of GFP expression in peripheral organs. In the liver, the biodistribution of AAV9 and AAV1&2 was 12.9- and 4.4-fold higher, respectively, compared to AAV6. The percentage of GFP-positive neurons in the FUS-targeted areas of the brain was comparable for AAV6-syn-GFP and AAV1&2-syn-GFP. In summary, MRIgFUS-mediated gene delivery with AAV6-syn-GFP had lower off-target biodistribution in the liver compared to AAV9 and AAV1&2, while providing neuronal GFP expression in the striatum and hippocampus.

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