EGFR/EGFRvIII Dual-Targeting Peptide-Mediated Drug Delivery for Enhanced Glioma Therapy

Cholesterol-modified peptide nanomicelles as a promising platform for cancer therapy: A review

Drug resistance, systemic toxicity, low solubility, and rapid clearance are common issues with chemotherapy drugs and other molecules used to treat cancer. The development of new therapeutic compounds and nanotherapy offers a solution to these issues. Therapeutic peptides have attracted great interest among these molecules due to their unique advantages, including low immunogenicity, efficient cellular internalization, deep tissue penetration, and low systemic toxicity. They have shown promise in cancer treatment by inducing apoptosis, necrosis, or cell lysis and promoting immunotherapy. In addition, peptides can deliver a range of cargoes, such as drugs, nucleic acids, imaging agents, and nanoparticles, and can specifically target cancer cells. However, problems such as their short half-life and low solubility limit their therapeutic use. Recent developments have addressed these constraints through structural alterations and nanoparticle formulations. In particular, cholesterol modification makes it possible for peptides to self-assemble into nanomicelles, which enhances their stability, half-life, and cell penetration. In this review, therapeutic peptides are presented as a versatile and successful cancer treatment option. The potential of cholesterol-modified peptide micelles as a reliable drug, nucleic acid, and imaging agent delivery system is also examined.

Engineering Multifunctional Peptide-Decorated Nanofibers for Targeted Delivery of Temozolomide across the Blood-Brain Barrier

A nanoplatform based on self-assembling peptides was developed with the ability to effectively transport and deliver a wide range of moieties across the blood-brain barrier (BBB) for the treatment of glioblastoma. Its surface was functionalized to have a targeted release of TMZ thanks to the targeting peptide that binds to EGFRvIII, which is overexpressed on tumor cells, and gH625, which acts as an enhancer of penetration. Furthermore, the on-demand release of TMZ was achieved through matrix metalloproteinase-9 (MMP-9) cleavage. Nanofibers were characterized for their stability, critical aggregation concentration, and morphology. Next, the effect on both 2D and 3D glioblastoma/astrocytoma (U-87) and glioma (U-118) cell lines was evaluated. The Annexin V/Propidium iodide showed an increase in necrotic and apoptotic cells, and the morphological analysis allowed to discover that both U-118 and U-87 spheroids are smaller in surface, perimeter, and Feret's diameter when treated with NF-TMZ. The developed nanofiber was demonstrated to permeate the BBB in vitro in a 3D spheroidal biodynamic BBB model. Finally, there were no cytotoxic effects of nanofibers without the drug on spheroids, while a significant decrease in viability was observed when NF-TMZ was used. Overall, these results open new opportunities for the evaluation of the efficacy and safety of this nanoplatform in in vivo studies.

Peptide‑based therapeutic strategies for glioma: Current state and prospects

Glioma is a prevalent form of primary malignant central nervous system tumor, characterized by its cellular invasiveness, rapid growth, and the presence of the blood-brain barrier (BBB)/blood-brain tumor barrier (BBTB). Current therapeutic approaches, such as chemotherapy and radiotherapy, have shown limited efficacy in achieving significant antitumor effects. Therefore, there is an urgent demand for new treatments. Therapeutic peptides represent an innovative class of pharmaceutical agents with lower immunogenicity and toxicity. They are easily modifiable via chemical means and possess deep tissue penetration capabilities which reduce side effects and drug resistance. These unique pharmacokinetic characteristics make peptides a rapidly growing class of new therapeutics that have demonstrated significant progress in glioma treatment. This review outlines the efforts and accomplishments in peptide-based therapeutic strategies for glioma. These therapeutic peptides can be classified into four types based on their anti-tumor function: tumor-homing peptides, inhibitor/antagonist peptides targeting cell surface receptors, interference peptides, and peptide vaccines. Furthermore, we briefly summarize the results from clinical trials of therapeutic peptides in glioma, which shows that peptide-based therapeutic strategies exhibit great potential as multifunctional players in glioma therapy.

Targeting the undruggable in glioblastoma using nano-based intracellular drug delivery

Glioblastoma (GBM) is a highly prevalent and aggressive brain tumor in adults with limited treatment response, leading to a 5-year survival rate of less than 5%. Standard therapies, including surgery, radiation, and chemotherapy, often fall short due to the tumor's location, hypoxic conditions, and the challenge of complete removal. Moreover, brain metastases from cancers such as breast and melanoma carry similarly poor prognoses. Recent advancements in nanomedicine offer promising solutions for targeted GBM therapies, with nanoparticles (NPs) capable of delivering chemotherapy drugs or radiation sensitizers across the blood-brain barrier (BBB) to specific tumor sites. Leveraging the enhanced permeability and retention effect, NPs can preferentially accumulate in tumor tissues, where compromised BBB regions enhance delivery efficiency. By modifying NP characteristics such as size, shape, and surface charge, researchers have improved circulation times and cellular uptake, enhancing therapeutic efficacy. Recent studies show that combining photothermal therapy with magnetic hyperthermia using AuNPs and magnetic NPs induces ROS-dependent apoptosis and immunogenic cell death providing dual-targeted, immune-activating approaches. This review discusses the latest NP-based drug delivery strategies, including gene therapy, receptor-mediated transport, and multi-modal approaches like photothermal-magnetic hyperthermia combinations, all aimed at optimizing therapeutic outcomes for GBM.

Brain gliomas: Diagnostic and therapeutic issues and the prospects of drug-targeted nano-delivery technology

Glioma is the most common intracranial malignant tumor, with severe difficulty in treatment and a low patient survival rate. Due to the heterogeneity and invasiveness of tumors, lack of personalized clinical treatment design, and physiological barriers, it is often difficult to accurately distinguish gliomas, which dramatically affects the subsequent diagnosis, imaging treatment, and prognosis. Fortunately, nano-delivery systems have demonstrated unprecedented capabilities in diagnosing and treating gliomas in recent years. They have been modified and surface modified to efficiently traverse BBB/BBTB, target lesion sites, and intelligently release therapeutic or contrast agents, thereby achieving precise imaging and treatment. In this review, we focus on nano-delivery systems. Firstly, we provide an overview of the standard and emerging diagnostic and treatment technologies for glioma in clinical practice. After induction and analysis, we focus on summarizing the delivery methods of drug delivery systems, the design of nanoparticles, and their new advances in glioma imaging and treatment in recent years. Finally, we discussed the prospects and potential challenges of drug-delivery systems in diagnosing and treating glioma.

Peptide-Hitchhiking for the Development of Nanosystems in Glioblastoma

Glioblastoma (GBM) remains the epitome of aggressiveness and lethality in the spectrum of brain tumors, primarily due to the blood-brain barrier (BBB) that hinders effective treatment delivery, tumor heterogeneity, and the presence of treatment-resistant stem cells that contribute to tumor recurrence. Nanoparticles (NPs) have been used to overcome these obstacles by attaching targeting ligands to enhance therapeutic efficacy. Among these ligands, peptides stand out due to their ease of synthesis and high selectivity. This article aims to review single and multiligand strategies critically. In addition, it highlights other strategies that integrate the effects of external stimuli, biomimetic approaches, and chemical approaches as nanocatalytic medicine, revealing their significant potential in treating GBM with peptide-functionalized NPs. Alternative routes of parenteral administration, specifically nose-to-brain delivery and local treatment within the resected tumor cavity, are also discussed. Finally, an overview of the significant obstacles and potential strategies to overcome them are discussed to provide a perspective on this promising field of GBM therapy.

Small Peptide-Based Nanodelivery Systems for Cancer Therapy and Diagnosis

Developing nano-biomaterials with tunable topology, size, and surface characteristics has shown tremendously favorable benefits in various biologic and clinical applications. Among various nano-biomaterials, peptide-based drug delivery systems offer multiple merits over other synthetic systems due to their enhanced bio- and cytocompatibility and desirable biochemical and biophysical properties. Currently, around 100 peptide-based drugs are clinically available for numerous therapeutic purposes. In conjugation with chemotherapeutic moieties, peptides demonstrate a remarkable ability to reduce nonspecific drug effects by improving drug targetability at cancer sites. This review encompasses a wide-ranging role played by different peptide-based nanostructures in cancer theranostics. Section 1 introduces the rising concern about cancer as a disease and further describes peptide-based nanomaterials as biomedical agents to tackle the ailment. The subsequent section explores the mechanistic pathways behind the self-assembly of peptides to form hierarchically distinct assemblies. The crux of our review lies in an exhaustive exploration of the applications of various types of peptide-based nanostructures in cancer therapy and diagnosis. SIGNIFICANCE STATEMENT: Peptide-based drug delivery systems possess superior biocompatibility, biochemical, and biophysical properties compared to other synthetic alternatives. The development of these nano-biomaterials with customizable topology, size, and surface characteristics have shown promising outcomes in biomedical contexts. Peptides in conjunction with chemotherapeutic agents exhibit the ability to enhance drug targetability at cancer sites, reducing nonspecific drug effects. This comprehensive review emphasizes the pivotal role of diverse peptide-based nanostructures as cancer theranostics, elucidating their potential in revolutionizing cancer therapy and diagnosis.

Therapeutic Peptides, Proteins and their Nanostructures for Drug Delivery and Precision Medicine

Peptide and protein nanostructures with tunable structural features, multifunctionality, biocompatibility and biomolecular recognition capacity enable development of efficient targeted drug delivery tools for precision medicine applications. In this review article, we present various techniques employed for the synthesis and self-assembly of peptides and proteins into nanostructures. We discuss design strategies utilized to enhance their stability, drug-loading capacity, and controlled release properties, in addition to the mechanisms by which peptide nanostructures interact with target cells, including receptor-mediated endocytosis and cell-penetrating capabilities. We also explore the potential of peptide and protein nanostructures for precision medicine, focusing on applications in personalized therapies and disease-specific targeting for diagnostics and therapeutics in diseases such as cancer.

Mirror-Image Single-Domain Antibody for a Novel Nonimmunogenic Drug Scaffold

Immunogenic responses by protein therapeutics often lead to reduced therapeutic effects and/or adverse effects via the generation of neutralizing antibodies and/or antidrug antibodies (ADA). Mirror-image proteins of the variable domain of the heavy chain of the heavy chain antibody (VHH) are potential novel protein therapeutics with high-affinity binding to target proteins and reduced immunogenicity because these mirror-image VHHs (d-VHHs) are less susceptible to proteolytic degradation in antigen-presenting cells (APCs). In this study, we investigated the preparation protocols of d-VHHs and their biological properties, including stereoselective target binding and immunogenicity. Initially, we established a facile synthetic process of two model VHHs [anti-GFP VHH and PMP12A2h1 (monomeric VHH of caplacizumab)] and their mirror-image proteins by three-step native chemical ligations (NCLs) from four peptide segments. The folded synthetic VHHs (l-anti-GFP VHH and l-PMP12A2h1) bound to the target proteins (EGFP and vWF-A1 domain, respectively), while their mirror-image proteins (d-anti-GFP VHH and d-PMP12A2h1) showed no binding to the native proteins. For biodistribution studies, l-VHH and d-VHH with single radioactive indium diethylenetriamine-pentaacid (111In-DTPA) labeling at the C-terminus were designed and synthesized by the established protocol. The distribution profiles were essentially similar between l-VHH and d-VHH, in which the probes accumulated in the kidney within 15 min after intravenous administration in mice, because of the small molecular size of VHHs. Comparative assessment of the immunogenicity responses revealed that d-VHH-induced levels of ADA generation were significantly lower than those of native VHH, regardless of the peptide sequences and administration routes. The resulting scaffold investigated should be applicable in the design of d-VHHs with various C-terminal CDR3 sequences, which can be identified by screening using display technologies.

Engineered Extracellular Vesicle-Delivered CRISPR/Cas9 for Radiotherapy Sensitization of Glioblastoma

Radiotherapy is a mainstay of glioblastoma (GBM) treatment; however, the development of therapeutic resistance has hampered the efficacy of radiotherapy, suggesting that additional treatment strategies are needed. Here, an in vivo loss-of-function genome-wide CRISPR screen was carried out in orthotopic tumors in mice subjected to radiation treatment to identify synthetic lethal genes associated with radiotherapy. Using functional screening and transcriptome analyses, glutathione synthetase (GSS) was found to be a potential regulator of radioresistance through ferroptosis. High GSS levels were closely related to poor prognosis and relapse in patients with glioma. Mechanistic studies demonstrated that GSS was associated with the suppression of radiotherapy-induced ferroptosis in glioma cells. The depletion of GSS resulted in the disruption of glutathione (GSH) synthesis, thereby causing the inactivation of GPX4 and iron accumulation, thus enhancing the induction of ferroptosis upon radiotherapy treatment. Moreover, to overcome the obstacles to broad therapeutic translation of CRISPR editing, we report a previously unidentified genome editing delivery system, in which Cas9 protein/sgRNA complex was loaded into Angiopep-2 (Ang) and the trans-activator of the transcription (TAT) peptide dual-modified extracellular vesicle (EV), which not only targeted the blood-brain barrier (BBB) and GBM but also permeated the BBB and penetrated the tumor. Our encapsulating EVs showed encouraging signs of GBM tissue targeting, which resulted in high GSS gene editing efficiency in GBM (up to 67.2%) with negligible off-target gene editing. These results demonstrate that a combination of unbiased genetic screens, and CRISPR-Cas9-based gene therapy is feasible for identifying potential synthetic lethal genes and, by extension, therapeutic targets.

Nanomedicine in cancer therapy

Cancer remains a highly lethal disease in the world. Currently, either conventional cancer therapies or modern immunotherapies are non-tumor-targeted therapeutic approaches that cannot accurately distinguish malignant cells from healthy ones, giving rise to multiple undesired side effects. Recent advances in nanotechnology, accompanied by our growing understanding of cancer biology and nano-bio interactions, have led to the development of a series of nanocarriers, which aim to improve the therapeutic efficacy while reducing off-target toxicity of the encapsulated anticancer agents through tumor tissue-, cell-, or organelle-specific targeting. However, the vast majority of nanocarriers do not possess hierarchical targeting capability, and their therapeutic indices are often compromised by either poor tumor accumulation, inefficient cellular internalization, or inaccurate subcellular localization. This Review outlines current and prospective strategies in the design of tumor tissue-, cell-, and organelle-targeted cancer nanomedicines, and highlights the latest progress in hierarchical targeting technologies that can dynamically integrate these three different stages of static tumor targeting to maximize therapeutic outcomes. Finally, we briefly discuss the current challenges and future opportunities for the clinical translation of cancer nanomedicines.

Ligand-installed polymeric nanocarriers for combination chemotherapy of EGFR-positive ovarian cancer

Combination chemotherapeutic drugs administered via a single nanocarrier for cancer treatment provides benefits in reducing dose-limiting toxicities, improving the pharmacokinetic properties of the cargo and achieving spatial-temporal synchronization of drug exposure for maximized synergistic therapeutic effects. In an attempt to develop such a multi-drug carrier, our work focuses on functional multimodal polypeptide-based polymeric nanogels (NGs). Diblock copolymers poly (ethylene glycol)-b-poly (glutamic acid) (PEG-b-PGlu) modified with phenylalanine (Phe) were successfully synthesized and characterized. Self-assembly behavior of the resulting polymers was utilized for the synthesis of NGs with hydrophobic domains in cross-linked polyion cores coated with inert PEG chains. The resulting NGs were small (ca. 70 nm in diameter) and were able to encapsulate the combination of drugs with different physicochemical properties such as cisplatin and neratinib. Drug combination-loaded NGs exerted a selective synergistic cytotoxicity towards EGFR overexpressing ovarian cancer cells. Moreover, we developed ligand-installed EGFR-targeted NGs and tested them as an EGFR-overexpressing tumor-specific delivery system. Both in vitro and in vivo, ligand-installed NGs displayed preferential associations with EGFR (+) tumor cells. Ligand-installed NGs carrying cisplatin and neratinib significantly improved the treatment response of ovarian cancer xenografts. We also confirmed the importance of simultaneous administration of the dual drug combination via a single NG system which provides more therapeutic benefit than individual drug-loaded NGs administered at equivalent doses. This work illustrates the potential of our carrier system to mediate efficient delivery of a drug combination to treat EGFR overexpressing cancers.

Functionalized nanoparticles crossing the brain-blood barrier to target glioma cells

Glioma is the most common tumor of the central nervous system (CNS), with a 5-year survival rate of <35%. Drug therapy, such as chemotherapeutic and immunotherapeutic agents, remains one of the main treatment modalities for glioma, including temozolomide, doxorubicin, bortezomib, cabazitaxel, dihydroartemisinin, immune checkpoint inhibitors, as well as other approaches such as siRNA, ferroptosis induction, etc. However, the filter function of the blood-brain barrier (BBB) reduces the amount of drugs needed to effectively target CNS tumors, making it one of the main reasons for poor drug efficacies in glioma. Thus, finding a suitable drug delivery platform that can cross the BBB, increase drug aggregation and retainment in tumoral areas and avoid accumulation in non-targeted areas remains an unsolved challenge in glioma drug therapy. An ideal drug delivery system for glioma therapy should have the following features: (1) prolonged drug life in circulation and effective penetration through the BBB; (2) adequate accumulation within the tumor (3) controlled-drug release modulation; (4) good clearance from the body without significant toxicity and immunogenicity, etc. In this regard, due to their unique structural features, nanocarriers can effectively span the BBB and target glioma cells through surface functionalization, providing a new and effective strategy for drug delivery. In this article, we discuss the characteristics and pathways of different nanocarriers for crossing the BBB and targeting glioma by listing different materials for drug delivery platforms, including lipid materials, polymers, nanocrystals, inorganic nanomaterials, etc.

Polymersome-based protein drug delivery - quo vadis?

Protein-based therapeutics are an attractive alternative to established therapeutic approaches and represent one of the fastest growing families of drugs. While many of these proteins can be delivered using established formulations, the intrinsic sensitivity of proteins to denaturation sometimes calls for a protective carrier to allow administration. Historically, lipid-based self-assembled structures, notably liposomes, have performed this function. After the discovery of polymersome-based targeted drug-delivery systems, which offer manifold advantages over lipid-based structures, the scientific community expected that such systems would take the therapeutic world by storm. However, no polymersome formulations have been commercialised. In this review article, we discuss key obstacles for the sluggish translation of polymersome-based protein nanocarriers into approved pharmaceuticals, which include limitations imparted by the use of non-degradable polymers, the intricacies of polymersome production methods, and the complexity of the in vivo journey of polymersomes across various biological barriers. Considering this complex subject from a polymer chemist's point of view, we highlight key areas that are worthy to explore in order to advance polymersomes to a level at which clinical trials become worthwhile and translation into pharmaceutical and nanomedical applications is realistic.

Self-Assembled Peptide-Based Nanodrugs: Molecular Design, Synthesis, Functionalization, and Targeted Tumor Bioimaging and Biotherapy

Functional nanomaterials as nanodrugs based on the self-assembly of inorganics, polymers, and biomolecules have showed wide applications in biomedicine and tissue engineering. Ascribing to the unique biological, chemical, and physical properties of peptide molecules, peptide is used as an excellent precursor material for the synthesis of functional nanodrugs for highly effective cancer therapy. Herein, recent progress on the design, synthesis, functional regulation, and cancer bioimaging and biotherapy of peptide-based nanodrugs is summarized. For this aim, first molecular design and controllable synthesis of peptide nanodrugs with 0D to 3D structures are presented, and then the functional customization strategies for peptide nanodrugs are presented. Then, the applications of peptide-based nanodrugs in bioimaging, chemotherapy, photothermal therapy (PTT), and photodynamic therapy (PDT) are demonstrated and discussed in detail. Furthermore, peptide-based drugs in preclinical, clinical trials, and approved are briefly described. Finally, the challenges and potential solutions are pointed out on addressing the questions of this promising research topic. This comprehensive review can guide the motif design and functional regulation of peptide nanomaterials for facile synthesis of nanodrugs, and further promote their practical applications for diagnostics and therapy of diseases.

Identification of a novel peptide ligand for the cancer-specific receptor mutation EGFRvIII using high-throughput sequencing of phage-selected peptides

We report here the selection and characterization of a novel peptide ligand using phage display targeted against the cancer-specific epidermal growth factor tyrosine kinase receptor mutation variant III (EGFRvIII). This receptor is expressed in several kinds of cancer: ovarian cancer, breast cancer and glioblastoma, but not in normal tissues. A 12-mer random peptide library was screened against EGFRvIII. Phage-selected peptides were sequenced in high-throughput by next generation sequencing (NGS), and their diversity was studied to identify highly abundant clones expected to bind with the highest affinities to EGFRvIII. The enriched peptides were characterized and their binding capacity towards stable cell lines expressing EGFRvIII, EGFR wild type (EGFR WT), or a low endogenous level of EGFR WT was confirmed by flow cytometry analysis. The best peptide candidate, VLGREEWSTSYW, was synthesized, and its binding specificity towards EGFRvIII was validated in vitro. Additionally, computational docking analysis suggested that the identified peptide binds selectively to EGFRvIII. The novel VLGREEWSTSYW peptide is thus a promising EGFRvIII-targeting agent for future applications in cancer diagnosis and therapy.

Multipronged Micelles-Hydrogel for Targeted and Prolonged Drug Delivery in Chronic Wound Infections

Chronic diabetic wounds are a growing threat globally. Many aspects contribute to its deterioration, including bacterial infection, unbalanced microenvironment, dysfunction of cell repair, etc. In this work, we designed a multipronged micelles-hydrogel platform loaded with curcumin and rifampicin (CRMs-hydrogel) for bacteria-infected chronic wound treatment. The curcumin- and rifampicin-loaded micelles (CRMs) exhibited both MMP9-responsive and epidermal growth factor receptor (EGFR)-targeting abilities. On the one hand, drugs could be released from micelles due to responsive disassembly by MMP9, a matrix metalloproteinase overexpressed in a chronic wound environment; on the other hand, CRMs showed specific targeting to EGFR on epithelial cells and fibroblasts and therefore increased intracellular drug delivery. The thermosensitive CRMs-hydrogel could form strong adhesion with the wound area and served as a suitable matrix for sustained release of CRMs directly at the wound bed, with excellent intracellular and extracellular bacterial elimination efficiency and wound healing promotion capability. We found that a single dose of CRMs-hydrogel achieved 99% antibacterial rate at the MRSA-infected diabetic wound, which effectively reduced inflammatory response and promoted the neovascularization and re-epithelialization process, with nearly half reduction of the skin barrier regeneration period. Collectively, our thermosensitive, MMP9-responsive, and targeted micelles-hydrogel nanoplatform is promising for chronic wound treatment.

Kill two birds with one stone: Engineered exosome-mediated delivery of cholesterol modified YY1-siRNA enhances chemoradiotherapy sensitivity of glioblastoma

Glioblastoma (GBM) is the most malignant tumor of the central nervous system in adults. Irradiation (IR) and temozolomide (TMZ) play an extremely important role in the treatment of GBM. However, major impediments to effective treatment are postoperative tumor recurrence and acquired resistance to chemoradiotherapy. Our previous studies confirm that Yin Yang 1 (YY1) is highly expressed in GBM, whereby it is associated with cell dedifferentiation, survival, and therapeutic resistance. Targeted delivery of small interfering RNA (siRNA) without blood-brain barrier (BBB) restriction for eradication of GBM represents a promising approach for therapeutic interventions. In this study, we utilize the engineering technology to generate T7 peptide-decorated exosome (T7-exo). T7 is a peptide specifically binding to the transferrin receptor. T7-exo shows excellent packaging and protection of cholesterol-modified Cy3-siYY1 while quickly releasing payloads in a cytoplasmic reductive environment. The engineered exosomes T7-siYY1-exo could deliver more effciently to GBM cells both in vitro and in vivo. Notably, in vitro experiments demonstrate that T7-siYY1-exo can enhance chemoradiotherapy sensitivity and reverse therapeutic resistance. Moreover, T7-siYY1-exo and TMZ/IR exert synergistic anti-GBM effect and significantly improves the survival time of GBM bearing mice. Our findings indicate that T7-siYY1-exo may be a potential approach to reverse the chemoradiotherapy resistance in GBM.

Ligand conjugated lipid-based nanocarriers for cancer theranostics

Cancer is one of the major health-related issues affecting the population worldwide and subsequently accounts for the second-largest death. Genetic and epigenetic modifications in oncogenes or tumor suppressor genes affect the regulatory systems that lead to the initiation and progression of cancer. Conventional methods, including chemotherapy/radiotherapy/appropriate combinational therapy and surgery, are being widely used for theranostics of cancer patients. Surgery is useful in treating localized tumors, but it is ineffective in treating metastatic tumors, which spread to other organs and result in a high recurrence rate and death. Also, the therapeutic application of free drugs is related to substantial issues such as poor absorption, solubility, bioavailability, high degradation rate, short shelf-life, and low therapeutic index. Therefore, these issues can be sorted out using nano lipid-based carriers (NLBCs) as promising drug delivery carriers. Still, at most, they fail to achieve site targeted drug delivery and detection. This can be achieved by selecting a specific ligand/antibody for its cognate receptor molecule expressed on the surface of cancer cell. In this review, we have mainly discussed the various types of ligands used to decorate NLBCs. A list of the ligands used to design nanocarriers to target malignant cells has been extensively undertaken. The approved ligand decorated lipid-based nanomedicines with their clinical status has been explained in tabulated form to provide a wider scope to the readers regarding ligand coupled NLBCs. This article is protected by copyright. All rights reserved.

An update on dual targeting strategy for cancer treatment

The key issue in the treatment of solid tumors is the lack of efficient strategies for the targeted delivery and accumulation of therapeutic cargoes in the tumor microenvironment (TME). Targeting approaches are designed for more efficient delivery of therapeutic agents to cancer cells while minimizing drug toxicity to normal cells and off-targeting effects, while maximizing the eradication of cancer cells. The highly complicated interrelationship between the physicochemical properties of nanoparticles, and the physiological and pathological barriers that are required to cross, dictates the need for the success of targeting strategies. Dual targeting is an approach that uses both purely biological strategies and physicochemical responsive smart delivery strategies to increase the accumulation of nanoparticles within the TME and improve targeting efficiency towards cancer cells. In both approaches, either one single ligand is used for targeting a single receptor on different cells, or two different ligands for targeting two different receptors on the same or different cells. Smart delivery strategies are able to respond to triggers that are typical of specific disease sites, such as pH, certain specific enzymes, or redox conditions. These strategies are expected to lead to more precise targeting and better accumulation of nano-therapeutics. This review describes the classification and principles of dual targeting approaches and critically reviews the efficiency of dual targeting strategies, and the rationale behind the choice of ligands. We focus on new approaches for smart drug delivery in which synthetic and/or biological moieties are attached to nanoparticles by TME-specific responsive linkers and advanced camouflaged nanoparticles.

Combinatorial therapeutic strategies for enhanced delivery of therapeutics to brain cancer cells through nanocarriers: current trends and future perspectives

Brain cancer is the most aggressive one among various cancers. It has a drastic impact on people's lives because of the failure in treatment efficacy of the currently employed strategies. Various strategies used to relieve pain in brain cancer patients and to prolong survival time include radiotherapy, chemotherapy, and surgery. Nevertheless, several inevitable limitations are accompanied by such treatments due to unsatisfactory curative effects. Generally, the treatment of cancers is very challenging due to many reasons including drugs’ intrinsic factors and physiological barriers. Blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB) are the two additional hurdles in the way of therapeutic agents to brain tumors delivery. Combinatorial and targeted therapies specifically in cancer show a very promising role where nanocarriers’ based formulations are designed primarily to achieve tumor-specific drug release. A dual-targeting strategy is a versatile way of chemotherapeutics delivery to brain tumors that gets the aid of combined ligands and mediators that cross the BBB and reaches the target site efficiently. In contrast to single targeting where one receptor or mediator is targeted, the dual-targeting strategy is expected to produce a multiple-fold increase in therapeutic efficacy for cancer therapy, especially in brain tumors. In a nutshell, a dual-targeting strategy for brain tumors enhances the delivery efficiency of chemotherapeutic agents via penetration across the blood-brain barrier and enhances the targeting of tumor cells. This review article highlights the ongoing status of the brain tumor therapy enhanced by nanoparticle based delivery with the aid of dual-targeting strategies. The future perspectives in this regard have also been highlighted.

Synthetic polymer material modified by d-peptide and its targeted application in the treatment of non-small cell lung cancer

Liposomes functionalized with targeted material offer a breakthrough compared with passive drug delivery. Here, we designed a polymer material, VAP-PEG₃₃₅₀-DSPE (VAP-PEG-DSPE), modified with a d-peptide VAP ligand that combines tumor-homing VAP with GRP78 receptor, a cancer marker on the membranes of many cancer cells. This paper establishes a docetaxel-loaded lipid nanodisk modified with multifunctional material to evaluate its anti-NSCLC efficacy in vivo. Additionally, the present study verified that VAP-conjugated nanodisks adapt to the developed tumor vasculature of the lung cancer microenvironment, making it a promising nanocarrier for NSCLC-targeting therapy. Moreover, in vitro and in vivo experiments demonstrated the targeting ability of VAP-DISK/DTX to tumor cells. Lung slices of mice also demonstrated the safety of VAP-DISK/DTX. The encapsulation efficiency of docetaxel-disks (VAP-DISK/DTX) was as high as 92.46±4.48%. Encapsulating anti-cancer drugs in lipid nanoparticles is thus an effective mechanism to change the pharmacokinetic and pharmacodynamic characteristics of drugs.

Gather wisdom to overcome barriers: Well-designed nano-drug delivery systems for treating gliomas

Due to the special physiological and pathological characteristics of gliomas, most therapeutic drugs are prevented from entering the brain. To improve the poor prognosis of existing therapies, researchers have been continuously developing non-invasive methods to overcome barriers to gliomas therapy. Although these strategies can be used clinically to overcome the blood‒brain barrier (BBB), the accurate delivery of drugs to the glioma lesions cannot be ensured. Nano-drug delivery systems (NDDS) have been widely used for precise drug delivery. In recent years, researchers have gathered their wisdom to overcome barriers, so many well-designed NDDS have performed prominently in preclinical studies. These meticulous designs mainly include cascade passing through BBB and targeting to glioma lesions, drug release in response to the glioma microenvironment, biomimetic delivery systems based on endogenous cells/extracellular vesicles/protein, and carriers created according to the active ingredients of traditional Chinese medicines. We reviewed these well-designed NDDS in detail. Furthermore, we discussed the current ongoing and completed clinical trials of NDDS for gliomas therapy, and analyzed the challenges and trends faced by clinical translation of these well-designed NDDS.

Combined integrin αvβ3 and lactoferrin receptor targeted docetaxel liposomes enhance the brain targeting effect and anti-glioma effect

The integrin α_vβ₃ receptor and Lactoferrin receptor (LfR) are over-expressed in both cerebral microvascular endothelial cells and glioma cells. RGD tripeptide and Lf can specifically bind with integrin α_vβ₃ receptor and LfR, respectively. In our study, RGD and Lf dual-modified liposomes loaded with docetaxel (DTX) were designed to enhance the brain targeting effect and treatment of glioma. Our in vitro studies have shown that RGD-Lf-LP can significantly enhance the cellular uptake of U87 MG cells and human cerebral microvascular endothelial cells (hCMEC/D3) when compared to RGD modified liposomes (RGD-LP) and Lf modified liposomes (Lf-LP). Free RGD and Lf competitively reduced the cellular uptake of RGD-Lf-LP, in particular, free RGD played a main inhibitory effect on cellular uptake of RGD-Lf-LP in U87 MG cells, yet free Lf played a main inhibitory effect on cellular uptake of RGD-Lf-LP in hCMEC/D3 cells. RGD-Lf-LP can also significantly increase penetration of U87 MG tumor spheroids, and RGD modification plays a dominating role on promoting the penetration of U87 MG tumor spheroids. The results of in vitro BBB model were shown that RGD-Lf-LP-C6 obviously increased the transport of hCMEC/D3 cell monolayers, and Lf modification plays a dominating role on increasing the transport of hCMEC/D3 cell monolayers. In vivo imaging proved that RGD-Lf-LP shows stronger targeting effects for brain orthotopic gliomas than that of RGD-LP and Lf-LP. The result of tissue distribution confirmed that RGD-LF-LP-DTX could significantly increase brain targeting after intravenous injection. Furthermore, RGD-LF-LP-DTX (a dose of 5 mg kg⁻¹ DTX) could significantly prolong the survival time of orthotopic glioma-bearing mice. In summary, RGD and LF dual modification are good combination for brain targeting delivery, RGD-Lf-LP-DTX could enhance brain targeting effects, and is thus a promising chemotherapeutic drug delivery system for treatment of glioma.

Advances in magnetic resonance imaging contrast agents for glioblastoma-targeting theranostics

Glioblastoma (GBM) is the most aggressive malignant brain tumour, with a median survival of 3 months without treatment and 15 months with treatment. Early GBM diagnosis can significantly improve patient survival due to early treatment and management procedures. Magnetic resonance imaging (MRI) using contrast agents is the preferred method for the preoperative detection of GBM tumours. However, commercially available clinical contrast agents do not accurately distinguish between GBM, surrounding normal tissue and other cancer types due to their limited ability to cross the blood–brain barrier, their low relaxivity and their potential toxicity. New GBM-specific contrast agents are urgently needed to overcome the limitations of current contrast agents. Recent advances in nanotechnology have produced alternative GBM-targeting contrast agents. The surfaces of nanoparticles (NPs) can be modified with multimodal contrast imaging agents and ligands that can specifically enhance the accumulation of NPs at GBM sites. Using advanced imaging technology, multimodal NP-based contrast agents have been used to obtain accurate GBM diagnoses in addition to an increased amount of clinical diagnostic information. NPs can also serve as drug delivery systems for GBM treatments. This review focuses on the research progress for GBM-targeting MRI contrast agents as well as MRI-guided GBM therapy.

Protease-Resistant Peptides for Targeting and Intracellular Delivery of Therapeutics

Peptides show high promise in the targeting and intracellular delivery of next-generation bio- and nano-therapeutics. However, the proteolytic susceptibility of peptides is one of the major limitations of their activity in biological environments. Numerous strategies have been devised to chemically enhance the resistance of peptides to proteolysis, ranging from N- and C-termini protection to cyclization, and including backbone modification, incorporation of amino acids with non-canonical side chains and conjugation. Since conjugation of nanocarriers or other cargoes to peptides for targeting and cell penetration may already provide some degree of shielding, the question arises about the relevance of using protease-resistant sequences for these applications. Aiming to answer this question, here we provide a critical review on protease-resistant targeting peptides and cell-penetrating peptides (CPPs). Two main approaches have been used on these classes of peptides: enantio/retro-enantio isomerization and cyclization. On one hand, enantio/retro-enantio isomerization has been shown to provide a clear enhancement in peptide efficiency with respect to parent L-amino acid peptides, especially when applied to peptides for drug delivery to the brain. On the other hand, cyclization also clearly increases peptide transport capacity, although contribution from enhanced protease resistance or affinity is often not dissected. Overall, we conclude that although conjugation often offers some degree of protection to proteolysis in targeting peptides and CPPs, modification of peptide sequences to further enhance protease resistance can greatly increase homing and transport efficiency.

Recent advances in polymeric core-shell nanocarriers for targeted delivery of chemotherapeutic drugs

The treatment effect of chemotherapeutics is often impeded by nonspecific biodistribution and limited biocompatibility. Polymeric core-shell nanocarriers (PCS NCs) composed of a polymer core and at least one shell have been widely applied for cancer therapy and have shown great potential in selectively delivering chemotherapeutic drugs to tumor sites. These PCS NCs can effectively ameliorate the delivery efficiency and therapeutic index of anticarcinogens by prolonging drug residence in the bloodstream, enhancing tumor tissue drug penetration, facilitating cellular drug uptake, controlling the spatiotemporal release of payloads, or codelivering two or more bioactive agents. This review summarizes recently published literature on using PCS NCs to transport chemotherapeutic drugs with poor aqueous solubility and discusses their design principles, structural features, functional properties, and potential limitations.

Biosensor-based assay of exosome biomarker for early diagnosis of cancer

Cancer imposes a severe threat to people's health and lives, thus pressing a huge medical and economic burden on individuals and communities. Therefore, early diagnosis of cancer is indispensable in the timely prevention and effective treatment for patients. Exosome has recently become an attractive cancer biomarker in noninvasive early diagnosis because of the unique physiology and pathology functions, which reflects remarkable information regarding the cancer microenvironment, and plays an important role in the occurrence and evolution of cancer. Meanwhile, biosensors have gained great attention for the detection of exosomes due to their superior properties, such as convenient operation, real-time readout, high sensitivity, and remarkable specificity, suggesting promising biomedical applications in the early diagnosis of cancer. In this review, the latest advances of biosensors regarding the assay of exosomes were summarized, and the superiorities of exosomes as markers for the early diagnosis of cancer were evaluated. Moreover, the recent challenges and further opportunities of developing effective biosensors for the early diagnosis of cancer were discussed.

Challenges towards Targeted Drug Delivery in Cancer Nanomedicines

Despite cancer nanomedicine celebrates already thirty years since its introduction, together with the achievements and progress in cancer treatment area, it still undergoes serious disadvantages that must be addressed. Since the first observation that macromolecules tend to accumulate in tumor tissue due to fenestrated endothelial of vasculature, considered as the “royal gate” in drug delivery field, more than dozens of nanoformulations have been approved and introduced into the practice for cancer treatment. Lipid, polymeric, and hybrid nanocarriers are biocompatible nano-drug delivery systems (NDDs) having suitable physicochemical properties and modulate payload release in response to specific chemical or physical stimuli. Biopharmaceutical properties of NDDs and their efficacy in animal models and humans can significantly affect their impact and perspective in nanomedicine. One of the future directions could be focusing on personalized cancer treatment, considering the heterogeneity and complexity of each patient tumor tissue and the designing of multifunctional targeted NDDs combining synthetic nanomaterials and biological components, like cellular membranes, circulating proteins, RNAi/DNAi, which enforce the efficacy of NDDs and boost their therapeutic effect.

Peptide-Enabled Targeted Delivery Systems for Therapeutic Applications

Receptor-targeting peptides have been extensively pursued for improving binding specificity and effective accumulation of drugs at the site of interest, and have remained challenging for extensive research efforts relating to chemotherapy in cancer treatments. By chemically linking a ligand of interest to drug-loaded nanocarriers, active targeting systems could be constructed. Peptide-functionalized nanostructures have been extensively pursued for biomedical applications, including drug delivery, biological imaging, liquid biopsy, and targeted therapies, and widely recognized as candidates of novel therapeutics due to their high specificity, well biocompatibility, and easy availability. We will endeavor to review a variety of strategies that have been demonstrated for improving receptor-specificity of the drug-loaded nanoscale structures using peptide ligands targeting tumor-related receptors. The effort could illustrate that the synergism of nano-sized structures with receptor-targeting peptides could lead to enrichment of biofunctions of nanostructures.

Conventional Nanosized Drug Delivery Systems for Cancer Applications

Clinical responses and tolerability of conventional nanocarriers (NCs) are sometimes different from those expected in anticancer therapy. Thus, new smart drug delivery systems (DDSs) with stimuli-responsive properties and novel materials have been developed. Several clinical trials demonstrated that these DDSs have better clinical therapeutic efficacy in the treatment of many cancers than free drugs. Composition of DDSs and their surface properties increase the specific targeting of therapeutics versus cancer cells, without affecting healthy tissues, and thus limiting their toxicity versus unspecific tissues. Herein, an extensive revision of literature on NCs used as DDSs for cancer applications has been performed using the available bibliographic databases.

Magnetic Resonance Signal Amplification by Reversible Exchange of Selective PyFALGEA Oligopeptide Ligands Towards Epidermal Growth Factor Receptors

The biorelevant PyFALGEA oligopeptide ligand, which is selective towards the epidermal growth factor receptor (EGFR), has been successfully employed as a substrate in magnetic resonance signal amplification by reversible exchange (SABRE) experiments. It is demonstrated that PyFALGEA and the iridium catalyst IMes form a PyFALGEA:IMes molecular complex. The interaction between PyFALGEA:IMes and H₂ results in a ternary SABRE complex. Selective 1D EXSY experiments reveal that this complex is labile, which is an essential condition for successful hyperpolarization by SABRE. Polarization transfer from parahydrogen to PyFALGEA is observed leading to significant enhancement of the ¹ H NMR signals of PyFALGEA. Different iridium catalysts and peptides are inspected to discuss the influence of their molecular structures on the efficiency of hyperpolarization. It is observed that PyFALGEA oligopeptide hyperpolarization is more efficient when an iridium catalyst with a sterically less demanding NHC ligand system such as IMesBn is employed. Experiments with shorter analogues of PyFALGEA, that is, PyLGEA and PyEA, show that the bulky phenylalanine from the PyFALGEA oligopeptide causes steric hindrance in the SABRE complex, which hampers hyperpolarization with IMes. Finally, a single-scan ¹ H NMR SABRE experiment of PyFALGEA with IMesBn revealed a unique pattern of NMR lines in the hydride region, which can be treated as a fingerprint of this important oligopeptide.

Urokinase receptor deficiency results in EGFR-mediated failure to transmit signals for cell survival and neurite formation in mouse neuroblastoma cells

Urokinase-type plasminogen activator uPA and its receptor (uPAR) are the central players in extracellular matrix proteolysis, which facilitates cancer invasion and metastasis. EGFR is one of the important components of uPAR interactome. uPAR/EGFR interaction controls signaling pathways that regulate cell survival, proliferation and migration. We have previously established that uPA binding to uPAR stimulates neurite elongation in neuroblastoma cells, while blocking uPA/uPAR interaction induces neurite branching and new neurite formation. Here we demonstrate that blocking the uPA binding to uPAR with anti-uPAR antibody decreases the level of pEGFR and its downstream pERK1/2, but does increase phosphorylation of Akt, p38 and c-Src Since long-term uPAR blocking results in a severe DNA damage, accompanied by PARP-1 proteolysis and Neuro2a cell death, we surmise that Akt, p38 and c-Src activation transmits a pro-apoptotic signal, rather than a survival. Serum deprivation resulting in enhanced neuritogenesis is accompanied by an upregulated uPAR mRNA expression, while EGFR mRNA remains unchanged. EGFR activation by EGF stimulates neurite growth only in uPAR-overexpressing cells but not in control or uPAR-deficient cells. In addition, AG1478-mediated inhibition of EGFR activity impedes neurite growth in control and uPAR-deficient cells, but not in uPAR-overexpressing cells. Altogether these data implicate uPAR as an important regulator of EGFR and ERK1/2 signaling, representing a novel mechanism which implicates urokinase system in neuroblastoma cell survival and differentiation.

Advances and Prospects of Vasculogenic Mimicry in Glioma: A Potential New Therapeutic Target?

Vasculogenic mimicry (VM) is the formation of a “vessel-like” structure without endothelial cells. VM exists in vascular-dependent solid tumors and is a special blood supply source involved in the highly invasive tumor progression. VM is observed in a variety of human malignant tumors and is closely related to tumor proliferation, invasion, and recurrence. Here, we review the mechanism, related signaling pathways, and molecular regulation of VM in glioma and discuss current research problems and the potential future applications of VM in glioma treatment. This review may provide a new viewpoint for glioma therapy.

Overcoming the Blood-Brain Barrier: Successes and Challenges in Developing Nanoparticle-Mediated Drug Delivery Systems for the Treatment of Brain Tumours

High-grade gliomas are still characterized by a poor prognosis, despite recent advances in surgical treatment. Chemotherapy is currently practiced after surgery, but its efficacy is limited by aspecific toxicity on healthy cells, tumour cell chemoresistance, poor selectivity, and especially by the blood–brain barrier (BBB). Thus, despite the large number of potential drug candidates, the choice of effective chemotherapeutics is still limited to few compounds. Malignant gliomas are characterized by high infiltration and neovascularization, and leaky BBB (the so-called blood–brain tumour barrier); surgical resection is often incomplete, leaving residual cells that are able to migrate and proliferate. Nanocarriers can favour delivery of chemotherapeutics to brain tumours owing to different strategies, including chemical stabilization of the drug in the bloodstream; passive targeting (because of the leaky vascularization at the tumour site); inhibition of drug efflux mechanisms in endothelial and cancer cells; and active targeting by exploiting carriers and receptors overexpressed at the blood–brain tumour barrier. Within this concern, a suitable nanomedicine-based therapy for gliomas should not be limited to cytotoxic agents, but also target the most important pathogenetic mechanisms, including cell differentiation pathways and angiogenesis. Moreover, the combinatorial approach of cell therapy plus nanomedicine strategies can open new therapeutical opportunities. The major part of attempted preclinical approaches on animal models involves active targeting with protein ligands, but, despite encouraging results, a few number of nanomedicines reached clinical trials, and most of them include drug-loaded nanocarriers free of targeting ligands, also because of safety and scalability concerns.

Dual Receptor-Targeted and Redox-Sensitive Polymeric Micelles Self-Assembled from a Folic Acid-Hyaluronic Acid-SS-Vitamin E Succinate Polymer for Precise Cancer Therapy

Purpose

Poor site-specific delivery and insufficient intracellular drug release in tumors are inherent disadvantages to successful chemotherapy. In this study, an extraordinary polymeric micelle nanoplatform was designed for the efficient delivery of paclitaxel (PTX) by combining dual receptor-mediated active targeting and stimuli response to intracellular reduction potential.

Methods

The dual-targeted redox-sensitive polymer, folic acid-hyaluronic acid-SS-vitamin E succinate (FHSV), was synthesized via an amidation reaction and characterized by ¹H-NMR. Then, PTX-loaded FHSV micelles (PTX/FHSV) were prepared by a dialysis method. The physiochemical properties of the micelles were explored. Moreover, in vitro cytological experiments and in vivo animal studies were carried out to evaluate the antitumor efficacy of polymeric micelles.

Results

The PTX/FHSV micelles exhibited a uniform, near-spherical morphology (148.8 ± 1.4 nm) and a high drug loading capacity (11.28% ± 0.25). Triggered by the high concentration of glutathione, PTX/FHSV micelles could quickly release their loaded drug into the release medium. The in vitro cytological evaluations showed that, compared with Taxol or single receptor-targeted micelles, FHSV micelles yielded higher cellular uptake by the dual receptor-mediated endocytosis pathway, thus leading to significantly superior cytotoxicity and apoptosis in tumor cells but less cytotoxicity in normal cells. More importantly, in the in vivo antitumor experiments, PTX/FHSV micelles exhibited enhanced tumor accumulation and produced remarkable tumor growth inhibition with minimal systemic toxicity.

Conclusion

Our results suggest that this well-designed FHSV polymer has promising potential for use as a vehicle of chemotherapeutic drugs for precise cancer therapy.

ɑvβ3-targeted liposomal drug delivery system with attenuated immunogenicity enabled by linear pentapeptide for glioma therapy

Owing to the binding capacity to ɑ_vβ₃ integrin overexpressed on glioma, vasculogenic mimicry and neovasculature, the peptide c(RGDyK) has been exploited pervasively to functionalize nanocarriers for targeted delivery of bioactives. The former study in our group substantiated the immunotoxicity of c(RGDyK)-modified liposome, and this unfavorable immunogenicity is known to compromise blood circulation, targeting efficacy and therapeutic outcome. Therefore, we need to find a superior alternative ligand in order to evade the exquisite immuno-sensitization. We developed mn by structure-guided peptide design and retro-inverso isomerization technique, which was experimentally substantiated to have exceptional binding affinity to ɑ_vβ₃ integrin. Besides mn does not have affinity toward normal liver cells and kidney cells, which c(RGDyK) possesses in a certain degree. Warranting that mn and c(RGDyK) anchored ɑ_vβ₃, we formulated peptide-tethered liposomes and investigated in vivo bio-fate. Compared with c(RGDyK)-modified liposome, mn-modified liposome presented longer blood circulation and reduced ingestion by Kupffer cells with decreased retention in liver accordingly, benefitting from attenuated anti-liposome IgG and IgM response elicited by multiple sequential doses. Those merits strengthened the anti-glioma efficacy of ɑ_vβ₃-targeted doxorubicin-loaded liposomes, proving the importance of immunocompatibility in process of targeted drug delivery.

Ligand-Installed Nanocarriers toward Precision Therapy

Development of drug-delivery systems that selectively target neoplastic cells has been a major goal of nanomedicine. One major strategy for achieving this milestone is to install ligands on the surface of nanocarriers to enhance delivery to target tissues, as well as to enhance internalization of nanocarriers by target cells, which improves accuracy, efficacy, and ultimately enhances patient outcomes. Herein, recent advances regarding the development of ligand-installed nanocarriers are introduced and the effect of their design on biological performance is discussed. Besides academic achievements, progress on ligand-installed nanocarriers in clinical trials is presented, along with the challenges faced by these formulations. Lastly, the future perspectives of ligand-installed nanocarriers are discussed, with particular emphasis on their potential for emerging precision therapies.

Gold Nanoparticles in Glioma Theranostics

Despite many endeavors to treat malignant gliomas in the last decades, the median survival of patients has not significantly improved. The infiltrative nature of high-grade gliomas and the impermeability of the blood-brain barrier to the most therapeutic agents remain major hurdles, impeding an efficacious treatment. Theranostic platforms bridging diagnosis and therapeutic modalities aim to surmount the current limitations in diagnosis and therapy of glioma. Gold nanoparticles (AuNPs) due to their biocompatibility and tunable optical properties have widely been utilized for an assortment of theranostic purposes. In this Review, applications of AuNPs as imaging probes, drug/gene delivery systems, radiosensitizers, photothermal transducers, and multimodal theranostic agents in malignant gliomas are discussed. This Review also aims to provide a perspective on cancer theranostic applications of AuNPs in future clinical trials.

All-stage precisional glioma targeted therapy enabled by a well-designed D-peptide

Uncontrollable cell proliferation and irreversible neurological damage make glioma one of the most deadly diseases in clinic. Besides the multiple biological barriers, glioma stem cells (GSCs) that are responsible for the maintenance and recurrence of tumor tissues also hinder the therapeutic efficacy of chemotherapy. Therefore, all-stage precisional glioma targeted therapy regimens that could efficiently deliver drugs to glioma cells and GSCs after overcoming multiple barriers have received increasing scrutiny. Methods: A polymeric micelle-based drug delivery system was developed by modifying a "Y-shaped" well-designed ligand of both GRP78 protein and quorum sensing receptor to achieve all-stage precisional glioma targeting, then we evaluated the targeting ability and barrier penetration ability both in vitro and in vivo. In order to achieve all-stage precisional therapy, we need kill both GSCs and glioma related cells. Parthenolide (PTL) has been investigated for its selective toxicity to glioma stem cells while Paclitaxel (PTX) and Temozolomide (TMZ) are widely used in experimental and clinical therapy of glioma respectively. So the in vivo anti-glioma effect of combination therapy was evaluated by Kaplan-Meier survival analysis and immunohistochemical (IHC) examination of tumor tissues. Results: The "Y-shaped" well-designed peptide, termed ^DWVAP, exhibited excellent glioma (and GSCs) homing and barrier penetration ability. When modified on micelle surface, ^DWVAP peptide significantly enhanced accumulation of micelles in brain and glioma. In addition, ^DWVAP micelles showed no immunogenicity and cytotoxicity, which could guarantee their safety when used in vivo. Treatment of glioma-bearing mice with PTL loaded ^DWVAP modified PEG-PLA micelles plus PTX loaded ^DWVAP modified PEG-PLA micelles or PTL loaded ^DWVAP modified PEG-PLA micelles plus TMZ showed improved anti-tumor efficacy in comparison to PTL and PTX loaded unmodified micelles or PTL loaded unmodified micelles plus TMZ. Conclusion: Combination of all-stage targeting strategy and concomitant use of chemotherapeutics and stem cell inhibitors could achieve precise targeted therapy for glioma.

Muscone/RI7217 co-modified upward messenger DTX liposomes enhanced permeability of blood-brain barrier and targeting glioma

Rationale: The dual-targeted drug delivery system was designed for enhancing permeation of the blood-brain barrier (BBB) and providing an anti-glioma effect. As transferrin receptor (TfR) is over-expressed by the brain capillary endothelial (hCMEC/D3) and glioma cells, a mouse monoclonal antibody, RI7217, with high affinity and selectivity for TfR, was used to study the brain targeted drug delivery system. Muscone, an ingredient of traditional Chinese medicine (TCM) musk, was used as the "guide" drug to probe the permeability of the BBB for drug delivery into the cerebrospinal fluid. This study investigated the combined effects of TCM aromatic resuscitation and modern receptor-targeted technology by the use of muscone/RI7217 co-modified docetaxel (DTX) liposomes for enhanced drug delivery to the brain for anti-glioma effect. Methods: Cellular drug uptake from the formulations was determined using fluorescence microscopy and flow cytometry. The drug penetrating ability into tumor spheroids were visualized using confocal laser scanning microscopy (CLSM). In vivo glioma-targeting ability of formulations was evaluated using whole-body fluorescent imaging system. The survival curve study was performed to evaluate the anti-glioma effect of the formulations. Results: The results showed that muscone and RI7217 co-modified DTX liposomes enhanced uptake into both hCMEC/D3 and U87-MG cells, increased penetration to the deep region of U87-MG tumor spheroids, improved brain targeting in vivo and prolonged survival time of nude mice bearing tumor. Conclusion: Muscone and RI7217 co-modified DTX liposomes were found to show improved brain targeting and enhanced the efficacy of anti-glioma drug treatment in vivo.

An Electrochemical Biosensor Designed by Using Zr-Based Metal-Organic Frameworks for the Detection of Glioblastoma-Derived Exosomes with Practical Application

Glioblastoma (GBM) is one of the most fatal tumors in the brain, and its early diagnosis remains technically challenging due to the complex repertoires of oncogenic alterations and blood-brain barrier (BBB). GBM-derived specific exosomes can cross the BBB and circulate in body fluids, so they can be noninvasive biomarkers for the early diagnosis of GBM. Herein, we propose a sensitive and label-free electrochemical biosensor designed by using Zr-based metal-organic frameworks (Zr-MOFs) for the detection of GBM-derived exosomes with practical application. In the design, a peptide ligand can specifically bind with human epidermal growth factor receptor (EGFR) and EGFR variant (v) III mutation (EGFRvIII), which are overexpressed on the GBM-derived exosomes. Meanwhile, Zr-MOFs encapsulated with methylene blue can absorb on the surface of the exosomes due to the interaction between Zr⁴⁺ and the intrinsic phosphate groups outside of exosomes. Consequently, the concentration of exosomes can be directly quantified by monitoring the electroactive molecules inside MOFs, ranging from 9.5 × 10³ to 1.9 × 10⁷ particles/μL with the detection of limit of 7.83 × 10³ particles/μL. Furthermore, this proposed biosensor can distinguish GBM patients from healthy groups, demonstrating the great prospect for early clinical diagnosis.

Co-delivery of GOLPH3 siRNA and gefitinib by cationic lipid-PLGA nanoparticles improves EGFR-targeted therapy for glioma

Glioblastoma is one of the most aggressive types of brain tumor. Epidermal growth factor receptors (EGFRs) are overexpressed in glioma, and EGFR amplifications and mutations lead to rapid proliferation and invasion. EGFR-targeted therapy might be an effective treatment for glioma. Gefitinib (Ge) is an EGFR tyrosine kinase inhibitor (TKI), and Golgi phosphoprotein 3 (GOLPH3) expression is associated with worse glioma prognosis. Downregulation of GOLPH3 could promote EGFR degradation. Here, an angiopep-2 (A2)-modified cationic lipid-poly (lactic-co-glycolic acid) (PLGA) nanoparticle (A2-N) was developed that can release Ge and GOLPH3 siRNA (siGOLPH3) upon entering glioma cells and therefore acts as a combinatorial anti-tumor therapy. The in vitro and in vivo studies proved that A2-N/Ge/siGOLPH3 successfully crossed the blood-brain barrier (BBB) and targeted glioma. Released siGOLPH3 effectively silenced GOLPH3 mRNA expression and further promoted EGFR and p-EGFR degradation. Released Ge also markedly inhibited EGFR signaling. This combined EGFR-targeted action achieved remarkable anti-glioma effects and could be a safe and effective treatment for glioma. KEY MESSAGES: Angiopep-2-modified cationic lipid polymer can penetrate the BBB. Gefitinib can inhibit EGFR signaling and block the autophosphorylation of critical tyrosine residues on EGFR. GOLPH3 siRNA can be transfected into glioma and downregulate GLOPH3 expression. A2-N/Ge/siGOLPH3 can inhibit glioma growth.

Engineered superparamagnetic iron oxide nanoparticles (SPIONs) for dual-modality imaging of intracranial glioblastoma via EGFRvIII targeting

In this work, a peptide-modified, biodegradable, nontoxic, brain-tumor-targeting nanoprobe based on superparamagnetic iron oxide nanoparticles (SPIONs) (which have been commonly used as T ₂-weighted magnetic resonance (MR) contrast agents) was successfully synthesized and applied for accurate molecular MR imaging and sensitive optical imaging. PEPHC1, a short peptide which can specifically bind to epidermal growth factor receptor variant III (EGFRvIII) that is overexpressed in glioblastoma, was conjugated with SPIONs to construct the nanoprobe. Both in vitro and in vivo MR and optical imaging demonstrated that the as-constructed nanoprobe was effective and sensitive for tumor targeting with desirable biosafety. Given its desirable properties such as a 100 nm diameter (capable of penetration of the blood-brain barrier) and bimodal imaging capability, this novel and versatile multimodal nanoprobe could bring a new perspective for elucidating intracranial glioblastoma preoperative diagnosis and the accuracy of tumor resection.

Dual-targeting nanoparticles with core-crosslinked and pH/redox-bioresponsive properties for enhanced intracellular drug delivery

Multifunctional nanoparticles (NPs) with high blood-stability, tumor-targeting ability, and stimuli-bioresponsive drug release behaviors are urgently demanded. Herein, folic acid (FA) and galactose (GAL) functionalized, core-crosslinked NPs (CC NPs) with dual-targeting and pH/redox-bioresponsive properties were developed based on amphiphilic FA-poly(6-O-methacryloyl-d-galactopyranose)-b-poly[2-(diisopropylamino) ethyl methacrylate-co-pyridyl disulfide methylacrylate] [FA-PMAgGP-b-P(DPA-co-PDEMA), termed as FA-PMgDP] block copolymers, and then investigated for facilitated hepatoma-targeting delivery of doxorubicin (DOX). A series of PMgDP copolymers were synthesized though two-step RAFT copolymerization followed by acid-induced acetal deprotection reaction. Their well-defined chemical structures and compositions were characterized by ¹H NMR and gel permeation chromatography. Nano-sized, non-crosslinked PMgDP NPs (PMgDP NC NPs) with sizes of less than 25 nm in aqueous solution were self-assembled via the solvent exchange method, and PMgDP CC NPs were readily prepared in the presence of dithiothreitol. The drug-loading content of PMgDP CC NPs was up to 15.8% and its entrapment efficiency was 89.0%. In normal physiological conditions, 11.6% of DOX was released from DOX-loaded PMgDP CC NPs at 25 h, whereas in analogous intracellular microenvironment, 95.5% was released at 11 h owing to the acid-induced protonation of tertiary amine and reductive cleavage of disulfide bond in the hydrophobic core. In a cellular uptake study, FA and GAL-mediated, active, dual-targeted DOX-loaded FA-PMgDP CC NPs showed a 3.54-fold increase in cellular uptake efficiency to HepG2 cells compared to that of shown by single GAL-targeted, DOX-loaded PMgDP NC NPs. Results of in vitro cytotoxicity study showed that blank FA-PMgDP CC NPs exhibited good biocompatibility, whereas dual-targeting DOX-loaded FA-PMgDP CC NPs increased cell apoptosis. Therefore, the above results indicated that the well-constructed FA-PMgDP CC NPs with multi-synergistic effect may serve as new nanocarriers in the field of precise hepatoma-targeting drug delivery.

Apolipoprotein E Peptide-Directed Chimeric Polymersomes Mediate an Ultrahigh-Efficiency Targeted Protein Therapy for Glioblastoma

The inability to cross the blood-brain barrier (BBB) prevents nearly all chemotherapeutics and biotherapeutics from the effective treatment of brain tumors, rendering few improvements in patient survival rates to date. Here, we report that apolipoprotein E peptide [ApoE, (LRKLRKRLL)₂C] specifically binds to low-density lipoprotein receptor members (LDLRs) and mediates superb BBB crossing and highly efficient glioblastoma (GBM)-targeted protein therapy in vivo. The in vitro BBB model studies reveal that ApoE induces 2.2-fold better penetration of the immortalized mouse brain endothelial cell line (bEnd.3) monolayer for chimeric polymersomes (CP) compared to Angiopep-2, the best-known BBB-crossing peptide used in clinical trials for GBM therapy. ApoE-installed CP (ApoE-CP) carrying saporin (SAP) displays a highly specific and potent antitumor effect toward U-87 MG cells with a low half-maximum inhibitory concentration of 14.2 nM SAP. Notably, ApoE-CP shows efficient BBB crossing as well as accumulation and penetration in orthotopic U-87 MG glioblastoma. The systemic administration of SAP-loaded ApoE-CP causes complete growth inhibition of orthotopic U-87 MG GBM without eliciting any observable adverse effects, affording markedly improved survival benefits. ApoE peptide provides an ultrahigh-efficiency targeting strategy for GBM therapy.

Renal-Clearable Peptide-Functionalized Ba2GdF7 Nanoparticles for Positive Tumor-Targeting Dual-Mode Bioimaging

Considering the dilemma between the effective tumor targeting and the avoidance of potential toxicity, it is desired to design nanoprobes with positive tumor-targeting and good renal clearance ability. In the present work, we developed epidermal growth factor receptor (EGFR)-targeted peptide-functionalized Ba₂GdF₇ nanoparticles (termed as pEGFR-targeted Ba₂GdF₇ NPs) for positive tumor-targeting magnetic resonance imaging and X-ray computed tomography (MRI/CT) dual-mode bioimaging. The positive tumor-targeting ability of pEGFR-targeted Ba₂GdF₇ NPs is achieved by conjugation of EGFR-targeted peptides on the 6.5 nm Ba₂GdF₇ NP surface through the formation of Gd-phosphonate coordinate bonds. The pEGFR-targeted Ba₂GdF₇ NPs display desirable cytocompatibility in the test concentration range and high binding affinity with lung cancer cells. In vivo MR and CT imaging results demonstrate that the pEGFR-targeted Ba₂GdF₇ NPs are able to be accumulated and detained within an engrafted A549 lung carcinoma, which enhances both MR and CT contrast in the tumor tissue. Systematic in vivo experimental results further demonstrate that the pEGFR-targeted Ba₂GdF₇ NPs have favorable in vivo renal clearance kinetics as well as reasonable in vivo biocompatibility.