Improving efficiency of adriamycin crossing blood brain barrier by combination of thermosensitive liposomes and hyperthermia

Real-time automatic temperature regulation during in vivo MRI-guided laser-induced thermotherapy (MR-LITT)

Precise control of tissue temperature during Laser-Induced Thermotherapy (LITT) procedures has the potential to improve the clinical efficiency and safety of such minimally invasive therapies. We present a method to automatically regulate in vivo the temperature increase during LITT using real-time rapid volumetric Magnetic Resonance thermometry (8 slices acquired every second, with an in-plane resolution of 1.4 mmx1.4 mm and a slice thickness of 3 mm) using the proton-resonance frequency (PRF) shift technique. The laser output power is adjusted every second using a feedback control algorithm (proportional-integral-derivative controller) to force maximal tissue temperature in the targeted region to follow a predefined temperature-time profile. The root-mean-square of the difference between the target temperature and the measured temperature ranged between 0.5 °C and 1.4 °C, for temperature increases between + 5 °C to + 30 °C above body temperature and a long heating duration (up to 15 min), showing excellent accuracy and stability of the method. These results were obtained on a 1.5 T clinical MRI scanner, showing a potential immediate clinical application of such a temperature controller during MR-guided LITT.

Nucleic acid drug vectors for diagnosis and treatment of brain diseases

Nucleic acid drugs have the advantages of rich target selection, simple in design, good and enduring effect. They have been demonstrated to have irreplaceable superiority in brain disease treatment, while vectors are a decisive factor in therapeutic efficacy. Strict physiological barriers, such as degradation and clearance in circulation, blood-brain barrier, cellular uptake, endosome/lysosome barriers, release, obstruct the delivery of nucleic acid drugs to the brain by the vectors. Nucleic acid drugs against a single target are inefficient in treating brain diseases of complex pathogenesis. Differences between individual patients lead to severe uncertainties in brain disease treatment with nucleic acid drugs. In this Review, we briefly summarize the classification of nucleic acid drugs. Next, we discuss physiological barriers during drug delivery and universal coping strategies and introduce the application methods of these universal strategies to nucleic acid drug vectors. Subsequently, we explore nucleic acid drug-based multidrug regimens for the combination treatment of brain diseases and the construction of the corresponding vectors. In the following, we address the feasibility of patient stratification and personalized therapy through diagnostic information from medical imaging and the manner of introducing contrast agents into vectors. Finally, we take a perspective on the future feasibility and remaining challenges of vector-based integrated diagnosis and gene therapy for brain diseases.

Nanocarriers Call the Last Shot in the Treatment of Brain Cancers

Our brain is protected by physio-biological barriers. The blood–brain barrier (BBB) main mechanism of protection relates to the abundance of tight junctions (TJs) and efflux pumps. Although BBB is crucial for healthy brain protection against toxins, it also leads to failure in a devastating disease like brain cancer. Recently, nanocarriers have been shown to pass through the BBB and improve patients’ survival rates, thus becoming promising treatment strategies. Among nanocarriers, inorganic nanocarriers, solid lipid nanoparticles, liposomes, polymers, micelles, and dendrimers have reached clinical trials after delivering promising results in preclinical investigations. The size of these nanocarriers is between 10 and 1000 nm and is modified by surface attachment of proteins, peptides, antibodies, or surfactants. Multiple research groups have reported transcellular entrance as the main mechanism allowing for these nanocarriers to cross BBB. Transport proteins and transcellular lipophilic pathways exist in BBB for small and lipophilic molecules. Nanocarriers cannot enter via the paracellular route, which is limited to water-soluble agents due to the TJs and their small pore size. There are currently several nanocarriers in clinical trials for the treatment of brain cancer. This article reviews challenges as well as fitting attributes of nanocarriers for brain tumor treatment in preclinical and clinical studies.

Electroporation-Based Therapy for Brain Tumors: A Review

Electroporation-based therapy (EBT), as a high-voltage-pulse technology has been prevalent with favorable clinical outcomes in the treatment of various solid tumors. This review paper aims to promote the clinical translation of EBT for brain tumors. First, we briefly introduced the mechanism of pore formation in a cell membrane activated by external electric fields using a single cell model. Then, we summarized and discussed the current in vitro and in vivo preclinical studies, in terms of (1) the safety and effectiveness of EBT for brain tumors in animal models, and (2) the blood-brain barrier (BBB) disruption induced by EBT. Two therapeutic effects could be achieved in EBT for brain tumors simultaneously, i.e., the tumor ablation induced by irreversible electroporation (IRE) and transient BBB disruption induced by reversible electroporation (RE). The BBB disruption could potentially improve the uptake of antitumor drugs thereby enhancing brain tumor treatment. The challenges that hinder the application of EBT in the treatment of human brain tumors are discussed in the review paper as well.

An insight into the risk factors of brain tumors and their therapeutic interventions

Brain tumors are an abnormal growth of cells in the brain, also known as multifactorial groups of neoplasm. Incidence rates of brain tumors increase rapidly, and it has become a leading cause of tumor related deaths globally. Several factors have potential risks for intracranial neoplasm. To date, the International Agency for Research on Cancer has classified the ionizing radiation and the N-nitroso compounds as established carcinogens and probable carcinogens respectively. Diagnosis of brain tumors is based on histopathology and suitable imaging techniques. Labeled amino acids and fluorodeoxyglucose with or without contrast-enhanced MRI are used for the evaluation of tumor traces. T2-weighted MRI is an advanced diagnostic implementation, used for the detection of low-grade gliomas. Treatment decisions are based on tumor size, location, type, patient's age and health status. Conventional therapeutic approaches for tumor treatment are surgery, radiotherapy and chemotherapy. While the novel strategies may include targeted therapy, electric field treatments and vaccine therapy. Inhibition of cyclin-dependent kinase inhibitors is an attractive tumor mitigation strategy for advanced-stage cancers; in the future, it may prove to be a useful targeted therapy. The blood-brain barrier poses a major hurdle in the transport of therapeutics towards brain tissues. Moreover, nanomedicine has gained a vital role in cancer therapy. Nano drug delivery system such as liposomal drug delivery has been widely used in the cancer treatment. Liposome encapsulated drugs have improved therapeutic efficacy than free drugs. Numerous treatment therapies for brain tumors are in advanced clinical research.

Enhancement of Therapies for Glioblastoma (GBM) Using Nanoparticle-based Delivery Systems

Glioblastoma multiforme (GBM) is the most aggressive type of malignant brain tumor. Current FDA-approved treatments include surgical resection, radiation, and chemotherapy, while hyperthermia, immunotherapy, and most relevantly, nanoparticle (NP)-mediated delivery systems or combinations thereof have shown promise in preclinical studies. Drug-carrying NPs are a promising approach to brain delivery as a result of their potential to facilitate the crossing of the blood-brain barrier (BBB) via two main types of transcytosis mechanisms: adsorptive-mediated transcytosis (AMT) and receptor-mediated transcytosis (RMT). Their ability to accumulate in the brain can thus provide local sustained release of tumoricidal drugs at or near the site of GBM tumors. NP-based drug delivery has the potential to significantly reduce drug-related toxicity, increase specificity, and consequently improve the lifespan and quality of life of patients with GBM. Due to significant advances in the understanding of the molecular etiology and pathology of GBM, the efficacy of drugs loaded into vectors targeting this disease has increased in both preclinical and clinical settings. Multitargeting NPs, such as those incorporating multiple specific targeting ligands, are an innovative technology that can lead to decreased off-target effects while simultaneously having increased accumulation and action specifically at the tumor site. Targeting ligands can include antibodies, or fragments thereof, and peptides or small molecules, which can result in a more controlled drug delivery system compared to conventional drug treatments. This review focuses on GBM treatment strategies, summarizing current options and providing a detailed account of preclinical findings with prospective NP-based approaches aimed at improving tumor targeting and enhancing therapeutic outcomes for GBM patients.

Drug repurposing using transcriptome sequencing and virtual drug screening in a patient with glioblastoma

Background Precision medicine and drug repurposing are attractive strategies, especially for tumors with worse prognosis. Glioblastoma is a highly malignant brain tumor with limited treatment options and short survival times. We identified novel BRAF (47-438del) and PIK3R1 (G376R) mutations in a glioblastoma patient by RNA-sequencing. Methods The protein expression of BRAF and PIK3R1 as well as the lack of EGFR expression as analyzed by immunohistochemistry corroborated RNA-sequencing data. The expression of additional markers (AKT, SRC, mTOR, NF-κB, Ki-67) emphasized the aggressiveness of the tumor. Then, we screened a chemical library of > 1500 FDA-approved drugs and > 25,000 novel compounds in the ZINC database to find established drugs targeting BRAF47-438del and PIK3R1-G376R mutated proteins. Results Several compounds (including anthracyclines) bound with higher affinities than the control drugs (sorafenib and vemurafenib for BRAF and PI-103 and LY-294,002 for PIK3R1). Subsequent cytotoxicity analyses showed that anthracyclines might be suitable drug candidates. Aclarubicin revealed higher cytotoxicity than both sorafenib and vemurafenib, whereas idarubicin and daunorubicin revealed higher cytotoxicity than LY-294,002. Liposomal formulations of anthracyclines may be suitable to cross the blood brain barrier. Conclusions In conclusion, we identified novel small molecules via a drug repurposing approach that could be effectively used for personalized glioblastoma therapy especially for patients carrying BRAF47-438del and PIK3R1-G376R mutations.

A combination of receptor mediated transcytosis and photothermal effect promotes BBB permeability and the treatment of meningitis using itraconazole

Fungal infections of the central nervous system (CNS) may lead to life-threatening meningitis. Itraconazole (ITZ) is an effective antifungal agent that can be used to treat various fungal infections; however, its poor solubility along with poor permeability of the blood-brain barrier (BBB) prevents it from treating meningitis. Receptor mediated transcytosis (RMT) shows modest efficacy in BBB crossing, while affinity and saturability of interactions between ligands and receptors account for the limited efficacy of RMT in crossing the BBB. Mild hyperthermia could temporarily disrupt the BBB to increase its permeability. Therefore, we speculated that the combination of mild hyperthermia with RMT could potentially increase BBB permeability of ITZ leading to improved efficacy in fungal meningitis. Here, we have constructed for the first time, apolipoprotein E (Apo E) mimicked peptide COG1410 modified polydopamine (PDA)-coated bovine serum albumin nanoparticles (ApoE-PDA@ITZ-NPs). Different levels of COG1410-modified NPs were prepared and characterized. ApoE-PDA@ITZ-NPs have a superior photothermal effect under 808 nm light irradiation and exhibited favorable plasma stability and photothermal stability. Moreover, the cellular uptake of nanoparticles increased with an increase in COG1410. H-ApoE-PDA@ITZ-NPs increased cellular uptake and in vitro BBB permeability by 4.2-fold and 4.8-fold, respectively, compared to the ITZ-NPs. Live imaging implied that H-ApoE-PDA@ITZ-NPs could significantly increase the distribution of ITZ in the brain under 808 nm light irradiation. Histopathological analysis of periodic acid-Schiff-stained brain sections of the H-ApoE-PDA@ITZ-NP treated C. albicans meningitis model indicated that H-ApoE-PDA@ITZ-NPs showed superior antifungal activity after 808 nm light irradiation. Hence, we report ApoE-PDA@ITZ-NPs in tandem with 808 nm irradiation as a novel strategy of RMT combination with a photothermal effect in enhancing BBB permeability to facilitate drug accumulation in the brain region and enhance the therapeutic efficacy of ITZ in meningitis.

Addressing the challenges to increase the efficiency of translating nanomedicine formulations to patients

INTRODUCTION

Nanotechnology is in a growth phase for drug delivery and medical imaging. Nanomaterials with unique properties present opportunities for encapsulation of therapeutics and imaging agents, along with conjugation to ligands for targeting. Favorable chemistry of nanomaterials can create formulations that address critical challenges for therapeutics, such as insolubility and a low capacity to cross the blood-brain-barrier (BBB) and intestinal wall.

AREAS COVERED

The authors investigate challenges faced during translation of nanomedicines while suggesting reasons as to why some nanoformulations have under-performed in clinical trials. They assess physiological barriers such as the BBB and gut mucus that nanomedicines must overcome to deliver cargos. They also provide an overview with examples of how nanomedicines can be designed to improve localization and site-specific delivery (e.g., encapsulation, bioconjugation, and triggered-release).

EXPERT OPINION

There are examples where nanomedicines have demonstrated improved efficacy of payload in humans; however, most of the advantages conferred were in improved pharmacokinetics and reduced toxicity. Problematic data show susceptibility of nanoformulations against natural protective mechanisms present in the body, including distribution impediment by physiological barriers and activation of the reticuloendothelial system. Further initiatives should address current challenges while expanding the scope of nanomedicine into advanced biomedical imaging and antibiotic delivery.

Hyperthermia treatment advances for brain tumors

Hyperthermia therapy (HT) of cancer is a well-known treatment approach. With the advent of new technologies, HT approaches are now important for the treatment of brain tumors. We review current clinical applications of HT in neuro-oncology and ongoing preclinical research aiming to advance HT approaches to clinical practice. Laser interstitial thermal therapy (LITT) is currently the most widely utilized thermal ablation approach in clinical practice mainly for the treatment of recurrent or deep-seated tumors in the brain. Magnetic hyperthermia therapy (MHT), which relies on the use of magnetic nanoparticles (MNPs) and alternating magnetic fields (AMFs), is a new quite promising HT treatment approach for brain tumors. Initial MHT clinical studies in combination with fractionated radiation therapy (RT) in patients have been completed in Europe with encouraging results. Another combination treatment with HT that warrants further investigation is immunotherapy. HT approaches for brain tumors will continue to a play an important role in neuro-oncology.

Thermosensitive Liposomes for Image-Guided Drug Delivery

Liposomes have been employed as cancer therapy clinically since the 1990s, with the primary benefit of reduced toxicity but no appreciable efficacy improvement. Thermosensitive liposomes (TSLs) are specifically formulated such that they release the encapsulated drug when exposed to hyperthermic temperatures in the fever range (~40-42°C) and have been investigated as cancer therapy for several decades, with first clinical trials initiated in the last decade. Combined with localized hyperthermia, TSLs allow precise drug delivery to a targeted region. Typically, the targeted tissue is exposed to localized hyperthermia facilitated by an image-guided hyperthermia device. Thus, TSLs enable image-guided drug delivery where drug is delivered to a tissue region identified by medical imaging. Recent TSL formulations are based on the more recent paradigm of intravascular triggered release, where drug is released rapidly (within seconds) while TSLs pass through the vasculature of the heated tissue region. The drug released within the blood then extravasates and is taken up by cancer cells. These TSLs enable up to 20-30 times higher tumor drug uptake compared to infusion of unencapsulated drug, and the dose locally delivered to the heated region can be modulated based on heating duration. This chapter reviews various TSL formulations, the different anticancer agents that have been encapsulated, as well as targeted cancer types. Further, the various hyperthermia devices that have been used for image-guided hyperthermia are reviewed, focusing on those that have been employed in human patients.

Nanotherapeutics Engineered to Cross the Blood-Brain Barrier for Advanced Drug Delivery to the Central Nervous System

Drug delivery to the brain remains challenging mainly due to the blood-brain barrier (BBB) that regulates the entrance of substances to the brain. Advances in nanotechnology have enabled the engineering of nanomedicines for biomedical applications including enhanced drug delivery into the brain. In this review, we describe strategies of nanomedicines engineered to traverse the BBB and deliver therapeutic molecules to target brain sites. We highlight the representative applications with materials including polymers, lipids, and inorganic elements for brain drug delivery. We finalize this review with the current challenges and future perspective of nanotherapeutics for advanced drug delivery to the brain.

Evolution of Magnetic Hyperthermia for Glioblastoma Multiforme Therapy

Glioblastoma multiforme (GBM) is the most common and aggressive type of glial tumor, and despite many recent advances, its prognosis remains dismal. Hence, new therapeutic approaches for successful GBM treatment are urgently required. Magnetic hyperthermia-mediated cancer therapy (MHCT), which is based on heating the tumor tissues using magnetic nanoparticles on exposure to an alternating magnetic field (AMF), has shown promising results in the preclinical studies conducted so far. The aim of this Review is to evaluate the progression of MHCT for GBM treatment and to determine its effectiveness on the treatment either alone or in combination with other adjuvant therapies. The preclinical studies presented MHCT as an effective treatment module for the reduction of tumor cell growth and increase in survival of the tumor models used. Over the years, much research has been done to prove MHCT alone as the missing notch for successful GBM therapy. However, very few combinatorial studies have been reported. Some of the clinical studies carried out so far depicted that MHCT could be applied safely while possessing minimal side effects. Finally, we believe that, in the future, advancements in magnetic nanosystems might contribute toward establishing MHCT as a potential treatment tool for glioma therapy.

Enhanced blood-brain barrier penetration and glioma therapy mediated by T7 peptide-modified low-density lipoprotein particles

Therapeutic outcome for the treatment of glioma was often limited due to the non-targeted nature and low permeability of drugs across the blood-brain barrier (BBB). An ideal glioma-targeted delivery system need to traverse the BBB and then target glioma cells with adequate optimized physiochemical properties and biocompatibility. However, it is an enormous challenge to the researchers to engineer the above-mentioned features into a single nanocarrier particle. New frontiers in nanomedicine are advancing the research of new biomaterials. In this study, we demonstrate a strategy for glioma targeting by encapsulating vincristine sulfate (VCR) into a naturally available low-density lipoprotein particles (LDL)-based drug delivery system with the modification of T7 peptide ligand (T7-LDL). LDL, endogenous lipid transporters, can specifically bind to brain endothelial cells and glioma cells via interacting with the low-density lipoprotein receptors (LDLR). T7 is a seven-peptide ligand of transferrin receptors (TfR) capable of circumventing the BBB and then targeting glioma. By combining the dual-targeting delivery effect of T7 peptide and parent LDL, T7-LDL displayed higher glioma localization than that of parent LDL. After loading with VCR, T7-LDL showed the most favorable antiglioma effect in vitro and in vivo. These results demonstrated that T7-LDL is an important potential drug delivery system for glioma-targeted therapy.

Emerging blood–brain-barrier-crossing nanotechnology for brain cancer theranostics

The advancements, perspectives, and challenges in blood–brain-barrier (BBB)-crossing nanotechnology for effective brain tumor delivery and highly efficient brain cancer theranostics.

Localized delivery of therapeutic doxorubicin dose across the canine blood-brain barrier with hyperthermia and temperature sensitive liposomes

Most drugs cannot penetrate the blood–brain barrier (BBB), greatly limiting the use of anti-cancer agents for brain cancer therapy. Temperature sensitive liposomes (TSL) are nanoparticles that rapidly release the contained drug in response to hyperthermia (>40 °C). Since hyperthermia also transiently opens the BBB, we hypothesized that localized hyperthermia can achieve drug delivery across the BBB when combined with TSL. TSL-encapsulated doxorubicin (TSL-Dox) was infused intravenously over 30 min at a dose of 0.94 mg/kg in anesthetized beagles (age ∼17 months). Following, a hyperthermia probe was placed 5–10 mm deep through one of four 3-mm skull burr holes. Hyperthermia was performed randomized for 15 or 30 min, at either 45 or 50 °C. Blood was drawn every 30 min to measure TSL-Dox pharmacokinetics. Nonsurvival studies were performed in four dogs, where brain tissue at the hyperthermia location was extracted following treatment to quantify doxorubicin uptake via high-performance liquid chromatography (HPLC) and to visualize cellular uptake via fluorescence microscopy. Survival studies for 6 weeks were performed in five dogs treated by a single hyperthermia application. Local doxorubicin delivery correlated with hyperthermia duration and ranged from 0.11 to 0.74 μg/g of brain tissue at the hyperthermia locations, with undetectable drug uptake in unheated tissue. Fluorescence microscopy demonstrated doxorubicin delivery across the BBB. Histopathology in Haematoxylin & Eosin (H&E) stained samples demonstrated localized damage near the probe. No animals in the survival group demonstrated significant neurological deficits. This study demonstrates that localized doxorubicin delivery to the brain can be facilitated by TSL-Dox with localized hyperthermia with no significant neurological deficits.

Neuro-Nano Interfaces: Utilizing Nano-Coatings and Nanoparticles to Enable Next-Generation Electrophysiological Recording, Neural Stimulation, and Biochemical Modulation

Neural interfaces provide a window into the workings of the nervous system-enabling both biosignal recording and modulation. Traditionally, neural interfaces have been restricted to implanted electrodes to record or modulate electrical activity of the nervous system. Although these electrode systems are both mechanically and operationally robust, they have limited utility due to the resultant macroscale damage from invasive implantation. For this reason, novel nanomaterials are being investigated to enable new strategies to chronically interact with the nervous system at both the cellular and network level. In this feature article, the use of nanomaterials to improve current electrophysiological interfaces, as well as enable new nano-interfaces to modulate neural activity via alternative mechanisms, such as remote transduction of electromagnetic fields are explored. Specifically, this article will review the current use of nanoparticle coatings to enhance electrode function, then an analysis of the cutting-edge, targeted nanoparticle technologies being utilized to interface with both the electrophysiological and biochemical behavior of the nervous system will be provided. Furthermore, an emerging, specialized-use case for neural interfaces will be presented: the modulation of the blood-brain barrier.

Laser-Induced Thermal Therapy in Neuro-Oncology: A Review

OBJECTIVES

Laser therapy has become an appealing treatment modality in neurosurgery. In this review, we report on the history, physics, surgical steps, indications and uses, and complications that have been reported to date.

METHODS

An extensive literature search was performed for laser interstitial thermal therapy (LITT) and laser therapy in the context of glial tumors, metastatic lesions, pediatric brain tumors, and radiation necrosis. Reported complications in each series also were reviewed.

RESULTS

In the past decade, multiple studies have demonstrated the use, outcomes, and complications associated with LITT in neurosurgery. These same studies have consistently reported an overall benefit of LITT in cases in which traditional surgical approaches may be limited by the patient's clinical status, tumor location, or overall prognosis. However, there have been complications reported from local effects of thermal damage, technical error, and edema development. Increased experience has reduced complications and brought more promising results.

CONCLUSIONS

With the advent of real-time monitoring and damage estimation, LITT has gained ground in the management of intracranial tumors. Larger scale trials must be performed to develop standard protocols to define specific indications for use. Further large clinical studies for LITT in non-oncologic cases are also of interest.

Dual-modified liposome codelivery of doxorubicin and vincristine improve targeting and therapeutic efficacy of glioma

Therapeutic outcome for the treatment of glioma was often limited due to drug resistance and low permeability of drug across the multiple physiological barriers, including the blood-brain barrier (BBB), and the blood-tumor barrier (BTB). In order to overcome these hurdles, we designed T7 and DA7R dual peptides-modified liposomes (abbreviated as T7/DA7R-LS) to efficiently co-delivery doxorubicin (DOX) and vincristine (VCR) to glioma in this study. T7 is a seven-peptide ligand of transferrin receptors (TfR) capable of circumventing the BBB and then targeting glioma. DA7R is a d-peptide ligand of vascular endothelial growth factor receptor 2 (VEGFR 2) overexpressed on angiogenesis, presenting excellent glioma-homing property. By combining the dual-targeting delivery effect, the dual-modified liposomes displayed higher glioma localization than that of single ligand-modified liposomes or free drug. After loading with DOX and VCR, T7/DA7R-LS showed the most favorable antiglioma effect in vivo. In conclusion, this dual-targeting, co-delivery strategy provides a potential method for improving brain drug delivery and antiglioma treatment efficacy.

Synergistic dual-modified liposome improves targeting and therapeutic efficacy of bone metastasis from breast cancer

Breast cancer frequently metastasizes to bone, where it leads to poor clinical prognosis. Due to the peculiarity of the bone microstructure, the uptake of drugs often happens at non-targeted sites, which produces a similar cytotoxicity in both cancerous and healthy cells. In this study, a rational strategy was implemented to take advantage of a combination of both an octapeptide with eight repeating sequences of aspartate (Asp8) and folate to create a more selective and efficient drug delivery system to target cancer cells in bone tissue. Asp8 and folate were conjugated to the distal ends of DSPE-PEG2000-maleimide and DSPE-PEG2000-amine to create DSPE-PEG2000-Asp8 and DSPE-PEG2000-Folate, respectively, which were incorporated onto the surface of a doxorubicin (DOX)-loaded liposomes (A/F-LS). Asp8, similar to the hydroxyapatite-binding domains of osteopontin and osteocalcin, has been used as bone-targeting moieties for exclusive delivery of drugs to bone. The folate moiety binds selectively to folate receptor-positive tumors. The dual-targeting effects were evaluated by both in vitro and in vivo experiments. By taking advantages of dual-targeting drug delivery, the dual-modified liposomal drug system could relieve pain and improve survival. Inspired by its enhanced therapeutic efficacy and low toxicity, DOX-loaded A/F-LS could serve as an effective drug system for targeted therapy of bone metastases.

Stereotactic Laser Interstitial Thermal Therapy for Recurrent High-Grade Gliomas

BACKGROUND

The value of maximal safe cytoreductive surgery in recurrent high-grade gliomas (HGGs) is gaining wider acceptance. However, patients may harbor recurrent tumors that may be difficult to access with open surgery. Laser interstitial thermal therapy (LITT) is emerging as a technique for treating a variety of brain pathologies, including primary and metastatic tumors, radiation necrosis, and epilepsy.

OBJECTIVE

To review the role of LITT in the treatment of recurrent HGGs, for which current treatments have limited efficacy, and to discuss the possible role of LITT in the disruption of the blood-brain barrier to increase delivery of chemotherapy locoregionally.

METHODS

A MEDLINE search was performed to identify 17 articles potentially appropriate for review. Of these 17, 6 reported currently commercially available systems and as well as magnetic resonance thermometry to monitor the ablation and, thus, were thought to be most appropriate for this review. These studies were then reviewed for complications associated with LITT. Ablation volume, tumor coverage, and treatment times were also reviewed.

RESULTS

Sixty-four lesions in 63 patients with recurrent HGGs were treated with LITT. Frontal (n = 34), temporal (n = 14), and parietal (n = 16) were the most common locations. Permanent neurological deficits were seen in 7 patients (12%), vascular injuries occurred in 2 patients (3%), and wound infection was observed in 1 patient (2%). Ablation coverage of the lesions ranged from 78% to 100%.

CONCLUSION

Although experience using LITT for recurrent HGGs is growing, current evidence is insufficient to offer a recommendation about its role in the treatment paradigm for recurrent HGGs.

ABBREVIATIONS

BBB, blood-brain barrierFDA, US Food and Drug AdministrationGBM, glioblastoma multiformeHGG, high-grade gliomaLITT, laser interstitial thermal therapy.

Enhanced blood brain barrier permeability and glioblastoma cell targeting via thermoresponsive lipid nanoparticles

Thermoresponsive targeting is used to deliver therapeutic agents at hyperthermic conditions (39-45 °C). However, available thermoresponsive drug delivery systems (TDDS), including liposomes, have a complex method of preparation involving toxic solvents and reagents. The objective of this in vitro study was to prepare and characterize thermoresponsive lipid nanoparticles (TLN) for treating glioblastoma, the most aggressive brain tumor whose treatment is limited by a low blood brain barrier (BBB) permeability of drugs. Thermoresponsive lipids were prepared by mixing liquid and solid fatty acids (0.1 : 1 to 2 : 1 ratio) and lipid mixtures exhibiting a solid-liquid phase transition at 39 °C were identified by plotting melting point against liquid contents. TLN were prepared by a hot melt encapsulation method using mono- or double-surfactant systems. TLN showed desirable size (<270 nm), zeta potential (-35 to -50 mV), spherical morphology and stability by FTIR studies. In the drug release studies, paclitaxel release was slow at 37 °C, however, it was released abruptly at 39 °C due to the faster diffusion rate from liquid state nanoparticles. During cytotoxicity studies, the unloaded TLN were non-toxic whereas paclitaxel loaded TLN showed higher cytotoxicity to glioblastoma cells at 39 °C (69% cell viability after one hour) compared to 37 °C (82% cell viability). The TLN showed higher permeability across an in vitro model of BBB at 39 °C due to a deformable liquid state which can squeeze through the tight junctions of the BBB. In conclusion, this study demonstrated that the TLN can be used as a safe and effective alternative to traditional TDDS with higher potential to target glioblastoma cells across the BBB.

Apoferritin Nanocage for Brain Targeted Doxorubicin Delivery

An ideal brain-targeted nanocarrier must be sufficiently potent to penetrate the blood-brain barrier (BBB) and sufficiently competent to target the cells of interest with adequate optimized physiochemical features and biocompatibility. However, it is an enormous challenge to the researchers to organize the above-mentioned properties into a single nanocarrier particle. New frontiers in nanomedicine are advancing the research of new biomaterials. Herein, we demonstrate a straightforward strategy for brain targeting by encapsulating doxorubicin (DOX) into a naturally available and unmodified apoferritin nanocage (DOX-loaded APO). APO can specifically bind to cells expressing transferrin receptor 1 (TfR1). Because of the high expression of TfR1 in both brain endothelial and glioma cells, DOX-loaded APO can cross the BBB and deliver drugs to the glioma with TfR1. Subsequent research demonstrated that the DOX-loaded APO had good physicochemical properties (particle size of 12.03 ± 0.42 nm, drug encapsulation efficiency of 81.8 ± 1.1%) and significant penetrating and targeting effects in the coculture model of bEnd.3 and C6 cells in vitro. In vivo imaging revealed that DOX-loaded APO accumulated specifically in brain tumor tissues. Additionally, in vivo tumor therapy experiments (at a dosage of 1 mg/kg DOX) demonstrated that a longer survival period was observed in mice that had been treated with DOX-loaded APO (30 days) compared with mice receiving free DOX solution (19 days).

Breaching barriers in glioblastoma. Part I: Molecular pathways and novel treatment approaches

Glioblastoma multiforme (GBM) is the most common primary brain tumour, and the most aggressive in nature. The prognosis for patients with GBM remains poor, with a median survival time of only 1-2 years. The treatment failure relies on the development of resistance by tumour cells and the difficulty of ensuring that drugs effectively cross the dual blood brain barrier/blood brain tumour barrier. The advanced molecular and genetic knowledge has allowed to identify the mechanisms responsible for temozolomide resistance, which represents the standard of care in GBM, along with surgical resection and radiotherapy. Such resistance has motivated the researchers to investigate new avenues for GBM treatment intended to improve patient survival. In this review, we provide an overview of major obstacles to effective treatment of GBM, encompassing biological barriers, cancer stem cells, DNA repair mechanisms, deregulated signalling pathways and autophagy. New insights and potential therapy approaches for GBM are also discussed, emphasizing localized chemotherapy delivered directly to the brain, immunotherapy, gene therapy and nanoparticle-mediated brain drug delivery.

Getting into the brain: liposome-based strategies for effective drug delivery across the blood-brain barrier

This review summarizes articles that have been reported in literature on liposome-based strategies for effective drug delivery across the blood–brain barrier. Due to their unique physicochemical characteristics, liposomes have been widely investigated for their application in drug delivery and in vivo bioimaging for the treatment and/or diagnosis of neurological diseases, such as Alzheimer’s, Parkinson’s, stroke, and glioma. Several strategies have been used to deliver drug and/or imaging agents to the brain. Covalent ligation of such macromolecules as peptides, antibodies, and RNA aptamers is an effective method for receptor-targeting liposomes, which allows their blood–brain barrier penetration and/or the delivery of their therapeutic molecule specifically to the disease site. Additionally, methods have been employed for the development of liposomes that can respond to external stimuli. It can be concluded that the development of liposomes for brain delivery is still in its infancy, although these systems have the potential to revolutionize the ways in which medicine is administered.

A pilot trial of doxorubicin containing phosphatidyldiglycerol based thermosensitive liposomes in spontaneous feline soft tissue sarcoma

PURPOSE

Doxorubicin (DOX)-loaded phosphatidyldiglycerol-based thermosensitive liposomes (DPPG₂-TSL-DOX) combined with local hyperthermia (HT) was evaluated in cats with locally advanced spontaneous fibrosarcomas (soft tissue sarcoma [STS]). The study was designed to evaluate the safety and pharmacokinetic profile of the drug. Results from four dose-levels are reported.

METHODS

Eleven client-owned cats with advanced STS were enrolled. Five cats received escalating doses of 0.1-0.4 mg/kg DOX (group I), three received 0.4 mg/kg constantly (group II) and three 0.6 mg/kg (group III) IV over 15 min. HT with a target temperature of 41.5 °C was started 15 min before drug application and continued for a total of 60 min. Six HT treatments were applied every other week using a radiofrequency applicator. Tumour growth was monitored by magnetic resonance imaging (MRI) and for dose level III also with ¹⁸F-FDG PET.

RESULTS

Treatment was generally well tolerated and reasons for premature study termination in four cats were not associated with drug-induced toxicity. No DPPG₂-TSL-DOX based hypersensitivity reaction was observed. One cat showed simultaneous partial response (PR) in MRI and positron emission tomography (PET) whereas one cat showed stable disease in MRI and PR in PET (both cats in dose level III). Pharmacokinetic measurements demonstrated DOX release triggered by HT.

CONCLUSION

DPPG₂-TSL-DOX + HT is a promising treatment option for advanced feline STS by means of targeted drug delivery. As MTD was not reached further investigation is warranted to determine if higher doses would result in even better tumour responses.

Stereotactic modulation of blood-brain barrier permeability to enhance drug delivery

Drug delivery in the CNS is limited by endothelial tight junctions forming the impermeable blood-brain barrier. The development of new treatment paradigms has previously been hampered by the restrictiveness of the blood-brain barrier to systemically administered therapeutics. With recent advances in stereotactic localization and noninvasive imaging, we have honed the ability to modulate, ablate, and rewire millimetric brain structures to precisely permeate the impregnable barrier. The wide range of focused radiations offers endless possibilities to disrupt endothelial permeability with different patterns and intensity following 3-dimensional coordinates offering a new world of possibilities to access the CNS, as well as to target therapies. We propose a review of the current state of knowledge in targeted drug delivery using noninvasive image-guided approaches. To this end, we focus on strategies currently used in clinics or in clinical trials such as targeted radiotherapy and magnetic resonance guided focused ultrasound, but also on more experimental approaches such as magnetically heated nanoparticles, electric fields, and lasers, techniques which demonstrated remarkable results both in vitro and in vivo. We envision that biodistribution and efficacy of systemically administered drugs will be enhanced with further developments of these promising strategies. Besides therapeutic applications, stereotactic platforms can be highly valuable in clinical applications for interventional strategies that can improve the targetability and efficacy of drugs and macromolecules. It is our hope that by showcasing and reviewing the current state of this field, we can lay the groundwork to guide future research in this realm.

In vitro screening of nanomedicines through the blood brain barrier: A critical review

The blood-brain barrier accounts for the high attrition rate of the treatments of most brain disorders, which therefore remain one of the greatest health-care challenges of the twenty first century. Against this background of hindrance to brain delivery, nanomedicine takes advantage of the assembly at the nanoscale of available biomaterials to provide a delivery platform with potential to raising brain levels of either imaging or therapeutic agents. Nevertheless, to prevent later failure due to ineffective drug levels at the target site, researchers have been endeavoring to develop a battery of in vitro screening procedures that can predict earlier in the drug discovery process the ability of these cutting-edge drug delivery platforms to cross the blood-brain barrier for biomedical purposes. This review provides an in-depth analysis of the currently available in vitro blood-brain barrier models (both cell-based and non-cell-based) with the focus on their suitability for understanding the biological brain distribution of forthcoming nanomedicines. The relationship between experimental factors and underlying physiological assumptions that would ultimately lead to a more predictive capacity of their in vivo performance, and those methods already assayed for the evaluation of the brain distribution of nanomedicines are comprehensively discussed.

Hyperthermic Laser Ablation of Recurrent Glioblastoma Leads to Temporary Disruption of the Peritumoral Blood Brain Barrier

BACKGROUND

Poor central nervous system penetration of cytotoxic drugs due to the blood brain barrier (BBB) is a major limiting factor in the treatment of brain tumors. Most recurrent glioblastomas (GBM) occur within the peritumoral region. In this study, we describe a hyperthemic method to induce temporary disruption of the peritumoral BBB that can potentially be used to enhance drug delivery.

METHODS

Twenty patients with probable recurrent GBM were enrolled in this study. Fourteen patients were evaluable. MRI-guided laser interstitial thermal therapy was applied to achieve both tumor cytoreduction and disruption of the peritumoral BBB. To determine the degree and timing of peritumoral BBB disruption, dynamic contrast-enhancement brain MRI was used to calculate the vascular transfer constant (Ktrans) in the peritumoral region as direct measures of BBB permeability before and after laser ablation. Serum levels of brain-specific enolase, also known as neuron-specific enolase, were also measured and used as an independent quantification of BBB disruption.

RESULTS

In all 14 evaluable patients, Ktrans levels peaked immediately post laser ablation, followed by a gradual decline over the following 4 weeks. Serum BSE concentrations increased shortly after laser ablation and peaked in 1-3 weeks before decreasing to baseline by 6 weeks.

CONCLUSIONS

The data from our pilot research support that disruption of the peritumoral BBB was induced by hyperthemia with the peak of high permeability occurring within 1-2 weeks after laser ablation and resolving by 4-6 weeks. This provides a therapeutic window of opportunity during which delivery of BBB-impermeant therapeutic agents may be enhanced.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01851733.

Small molecule therapeutic-loaded liposomes as therapeutic carriers: from development to clinical applications

In this review, various methods and mechanisms for encapsulation of small therapeutic molecules in liposomes for targeted delivery and triggered release, as well as their potential in the clinical uses, are discussed.

Thermal Therapy Approaches for Treatment of Brain Tumors in Animals and Humans

Primary brain tumors are often aggressive, with short survival from time of diagnosis even with standard of care therapies such as surgery, chemotherapy, and radiation therapy. Thermal therapies have been extensively investigated as both primary and adjuvant therapy. Although thermal therapies are not yet widely used clinically, there have been several promising approaches demonstrated in both animals and humans. This review presents thermal therapy approaches in animal and human studies, including both hyperthermia (temperatures ~42°C-45°C) and thermal ablation (temperatures > 50°C). Hyperthermia is primarily used as adjuvant to chemotherapy and radiotherapy, and is the most widely studied radiation sensitizer where enhanced efficacy has been shown in human patients with brain cancer. Hyperthermia has additional beneficial effects such as immunogenic effects, and opening of the bloodbrain barrier to potentially enhance drug delivery, for example in combination with nanoparticle drug delivery systems. Thermal ablation uses high temperatures for direct local tumor destruction, and it found its way into clinical use as laser interstitial thermal therapy (LITT). This review presents various hyperthermia and ablation approaches, including a review of different devices and methods that have been used for thermal therapies, such as radiofrequency/microwaves, laser, high-intensity focused ultrasound, and magnetic nanoparticles. Current research efforts include the combination of advanced thermal therapy devices, such as focused ultrasound with radiation, as well as the use of thermal therapies to enhance chemotherapy delivery across the blood-brain barrier.

Nanoparticles: Novel vehicles in treatment of Glioblastoma

Glioblastoma multiform (GBM) is the most common brain tumor. The current GBM treatments comprise of radiation therapy, chemotherapy and surgery. One of the most important problems regarding the treatment of GBM is the presence of blood brain barrier (BBB) which inhibits the efficient drug delivery into central nervous system (CNS). Nanothechnology can help to deliver therapeutic drugs into CNS through crossing the BBB. There are different types of nanoparticles (Nps) which can be manipulated for clinical applications as a treatment for CNS-related disorders. In this review, we will discuss the role of Nps in the treatment of GBM.

Neurosurgical Techniques for Disruption of the Blood-Brain Barrier for Glioblastoma Treatment

The blood-brain barrier remains a main hurdle to drug delivery to the brain. The prognosis of glioblastoma remains grim despite current multimodal medical management. We review neurosurgical technologies that disrupt the blood-brain barrier (BBB). We will review superselective intra-arterial mannitol infusion, focused ultrasound, laser interstitial thermotherapy, and non-thermal irreversible electroporation (NTIRE). These technologies can lead to transient BBB and blood-brain tumor barrier disruption and allow for the potential of more effective local drug delivery. Animal studies and preliminary clinical trials show promise for achieving this goal.

Stereotactic laser ablation of high-grade gliomas

Evolving research has demonstrated that surgical cytoreduction of a high-grade glial neoplasm is an important factor in improving the prognosis of these difficult tumors. Recent advances in intraoperative imaging have spurred the use of stereotactic laser ablation (laser interstitial thermal therapy [LITT]) for intracranial lesions. Among other targets, laser ablation has been used in the focal treatment of high-grade gliomas (HGGs). The revived application of laser ablation for gliomas parallels major advancements in intraoperative adjuvants and groundbreaking molecular advances in neuro-oncology. The authors review the research on stereotactic LITT for the treatment of HGGs and provide a potential management algorithm for HGGs that incorporates LITT in clinical practice.

Alternating magnetic field-induced hyperthermia increases iron oxide nanoparticle cell association/uptake and flux in blood-brain barrier models

PURPOSE

Superparamagnetic iron oxide nanoparticles (IONPs) are being investigated for brain cancer therapy because alternating magnetic field (AMF) activates them to produce hyperthermia. For central nervous system applications, brain entry of diagnostic and therapeutic agents is usually essential. We hypothesized that AMF-induced hyperthermia significantly increases IONP blood-brain barrier (BBB) association/uptake and flux.

METHODS

Cross-linked nanoassemblies loaded with IONPs (CNA-IONPs) and conventional citrate-coated IONPs (citrate-IONPs) were synthesized and characterized in house. CNA-IONP and citrate-IONP BBB cell association/uptake and flux were studied using two BBB Transwell(®) models (bEnd.3 and MDCKII cells) after conventional and AMF-induced hyperthermia exposure.

RESULTS

AMF-induced hyperthermia for 0.5 h did not alter CNA-IONP size but accelerated citrate-IONP agglomeration. AMF-induced hyperthermia for 0.5 h enhanced CNA-IONP and citrate-IONP BBB cell association/uptake. It also enhanced the flux of CNA-IONPs across the two in vitro BBB models compared to conventional hyperthermia and normothermia, in the absence of cell death. Citrate-IONP flux was not observed under these conditions. AMF-induced hyperthermia also significantly enhanced paracellular pathway flux. The mechanism appears to involve more than the increased temperature surrounding the CNA-IONPs.

CONCLUSIONS

Hyperthermia induced by AMF activation of CNA-IONPs has potential to increase the BBB permeability of therapeutics for the diagnosis and therapy of various brain diseases.

Drug delivery strategies to enhance the permeability of the blood-brain barrier for treatment of glioma

Gliomas are amongst the most insidious and destructive types of brain cancer and are associated with a poor prognosis, frequent recurrences, and extremely high lethality despite combination treatment of surgery, radiotherapy, and chemotherapy. The existence of the blood–brain barrier (BBB) restricts the delivery of therapeutic molecules into the brain and offers the clinical efficacy of many pharmaceuticals that have been demonstrated to be effective for other kinds of tumors. This challenge emphasizes the need to be able to deliver drugs effectively across the BBB to reach the brain parenchyma. Enhancement of the permeability of the BBB and being able to transport drugs across it has been shown to be a promising strategy to improve drug absorption and treatment efficacy. This review highlights the innovative technologies that have been introduced to enhance the permeability of the BBB and to obtain an optimal distribution and concentration of drugs in the brain to treat gliomas, such as nanotechniques, hyperthermia techniques, receptor-mediated transport, cell-penetrating peptides, and cell-mediated delivery.

Localized RNAi therapeutics of chemoresistant grade IV glioma using hyaluronan-grafted lipid-based nanoparticles

Glioblastoma multiforme (GBM) is one of the most infiltrating, aggressive, and poorly treated brain tumors. Progress in genomics and proteomics has paved the way for identifying potential therapeutic targets for treating GBM, yet the vast majority of these leading drug candidates for the treatment of GBM are ineffective, mainly due to restricted passages across the blood-brain barrier. Nanoparticles have been emerged as a promising platform to treat different types of tumors due to their ability to transport drugs to target sites while minimizing adverse effects. Herein, we devised a localized strategy to deliver RNA interference (RNAi) directly to the GBM site using hyaluronan (HA)-grafted lipid-based nanoparticles (LNPs). These LNPs having an ionized lipid were previously shown to be highly effective in delivering small interfering RNAs (siRNAs) into various cell types. LNP's surface was functionalized with hyaluronan (HA), a naturally occurring glycosaminoglycan that specifically binds the CD44 receptor expressed on GBM cells. We found that HA-LNPs can successfully bind to GBM cell lines and primary neurosphers of GBM patients. HA-LNPs loaded with Polo-Like Kinase 1 (PLK1) siRNAs (siPLK1) dramatically reduced the expression of PLK1 mRNA and cumulated in cell death even under shear flow that simulate the flow of the cerebrospinal fluid compared with control groups. Next, a human GBM U87MG orthotopic xenograft model was established by intracranial injection of U87MG cells into nude mice. Convection of Cy3-siRNA entrapped in HA-LNPs was performed, and specific Cy3 uptake was observed in U87MG cells. Moreover, convection of siPLK1 entrapped in HA-LNPs reduced mRNA levels by more than 80% and significantly prolonged survival of treated mice in the orthotopic model. Taken together, our results suggest that RNAi therapeutics could effectively be delivered in a localized manner with HA-coated LNPs and ultimately may become a therapeutic modality for GBM.

Blood-brain barrier models and their relevance for a successful development of CNS drug delivery systems: a review

During the research and development of new drugs directed at the central nervous system, there is a considerable attrition rate caused by their hampered access to the brain by the blood-brain barrier. Throughout the years, several in vitro models have been developed in an attempt to mimic critical functionalities of the blood-brain barrier and reliably predict the permeability of drug candidates. However, the current challenge lies in developing a model that retains fundamental blood-brain barrier characteristics and simultaneously remains compatible with the high throughput demands of pharmaceutical industries. This review firstly describes the roles of all elements of the neurovascular unit and their influence on drug brain penetration. In vitro models, including non-cell based and cell-based models, and in vivo models are herein presented, with a particular emphasis on their methodological aspects. Lastly, their contribution to the improvement of brain drug delivery strategies and drug transport across the blood-brain barrier is also discussed.

Bioengineering strategies for designing targeted cancer therapies

The goals of bioengineering strategies for targeted cancer therapies are (1) to deliver a high dose of an anticancer drug directly to a cancer tumor, (2) to enhance drug uptake by malignant cells, and (3) to minimize drug uptake by nonmalignant cells. Effective cancer-targeting therapies will require both passive- and active-targeting strategies and a thorough understanding of physiologic barriers to targeted drug delivery. Designing a targeted therapy includes the selection and optimization of a nanoparticle delivery vehicle for passive accumulation in tumors, a targeting moiety for active receptor-mediated uptake, and stimuli-responsive polymers for control of drug release. The future direction of cancer targeting is a combinatorial approach, in which targeting therapies are designed to use multiple-targeting strategies. The combinatorial approach will enable combination therapy for delivery of multiple drugs and dual ligand targeting to improve targeting specificity. Targeted cancer treatments in development and the new combinatorial approaches show promise for improving targeted anticancer drug delivery and improving treatment outcomes.

Application of nanoparticles on diagnosis and therapy in gliomas

Glioblastoma multiforme (GBM) is one of the most deadly diseases that affect humans, and it is characterized by high resistance to chemotherapy and radiotherapy. Its median survival is only fourteen months, and this dramatic prognosis has stilled without changes during the last two decades; consequently GBM remains as an unsolved clinical problem. Therefore, alternative diagnostic and therapeutic approaches are needed for gliomas. Nanoparticles represent an innovative tool in research and therapies in GBM due to their capacity of self-assembly, small size, increased stability, biocompatibility, tumor-specific targeting using antibodies or ligands, encapsulation and delivery of antineoplastic drugs, and increasing the contact surface between cells and nanomaterials. The active targeting of nanoparticles through conjugation with cell surface markers could enhance the efficacy of nanoparticles for delivering several agents into the tumoral area while significantly reducing toxicity in living systems. Nanoparticles can exploit some biological pathways to achieve specific delivery to cellular and intracellular targets, including transport across the blood-brain barrier, which many anticancer drugs cannot bypass. This review addresses the advancements of nanoparticles in drug delivery, imaging, diagnosis, and therapy in gliomas. The mechanisms of action, potential effects, and therapeutic results of these systems and their future applications in GBM are discussed.

Recent trends in multifunctional liposomal nanocarriers for enhanced tumor targeting

Liposomes are delivery systems that have been used to formulate a vast variety of therapeutic and imaging agents for the past several decades. They have significant advantages over their free forms in terms of pharmacokinetics, sensitivity for cancer diagnosis and therapeutic efficacy. The multifactorial nature of cancer and the complex physiology of the tumor microenvironment require the development of multifunctional nanocarriers. Multifunctional liposomal nanocarriers should combine long blood circulation to improve pharmacokinetics of the loaded agent and selective distribution to the tumor lesion relative to healthy tissues, remote-controlled or tumor stimuli-sensitive extravasation from blood at the tumor's vicinity, internalization motifs to move from tumor bounds and/or tumor intercellular space to the cytoplasm of cancer cells for effective tumor cell killing. This review will focus on current strategies used for cancer detection and therapy using liposomes with special attention to combination therapies.