Identification and characterization of a novel peptide ligand of epidermal growth factor receptor for targeted delivery of therapeutics

Synthesis of a novel 99mTc labeled GE11 peptide for EGFR SPECT imaging

PURPOSE

This study investigated a novel SPECT agent for the noninvasive imaging of EGFR-overexpressing tumors.

METHODS

The EGFR-targeting peptide GE11 was synthesized with the introduction of four amino acids (GGGC) to its C-terminal to act as a strong chelator and radiolabeled using ^99mTc. The radiochemical yield of the ^99mTc-peptide-GE11 were evaluated using RP-HPLC. Cellular assays of the probe were performed on two NSCLC cell lines: A549 (high expression) and H23 (low expression). Biodistribution and SPECT imaging were performed in BALB/c nude mice bearing A549 and H23 NSCLC xenografts.

RESULTS

The ^99mTc-peptide-GE11 was prepared at high efficiency with radiochemical yield of 98.40 ± 1.00 % and it showed favorable stability. The cellular uptake was significantly higher in A549 than in H23 at all time points (especially at 1 h, which was 10.34 ± 0.72 and 2.04 ± 0.18, respectively). A nearly 56% reduction in probe uptake was observed after pretreatment with excess unlabeled peptides. The performance of SPECT imaging and biodistribution demonstrated higher uptake of the ^99mTc-peptide-GE11 in A549 xenograft than in H23 xenografts.

CONCLUSION

The new SPECT tracer ^99mTc-peptide-GE11 showed EGFR specificity, favorable pharmacokinetics and great potential for EGFR-targeted imaging.

GE11 peptide-installed chimaeric polymersomes tailor-made for high-efficiency EGFR-targeted protein therapy of orthotopic hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains a leading malignancy with a high mortality and little improvement in treatments. Protein drugs though known for their extraordinary potency and specificity have rarely been investigated for HCC therapy owing to lack of appropriate delivery systems. Here, we designed GE11 peptide-installed chimaeric polymersomes (GE11-CPs) for high-efficiency EGFR-targeted protein therapy of orthotopic SMMC-7721 HCC-bearing nude mice. GE11-CPs were assembled from poly(ethylene glycol)-b-poly(trimethylene carbonate-co-dithiolane trimethylene carbonate)-b-poly(aspartic acid) (PEG-P(TMC-DTC)-PAsp) and GE11-functionalized PEG-P(TMC-DTC), which allowed efficient loading and protection of proteins in the watery interior and fine-tuning of GE11 densities at the surface. CPs with short PAsp segments (degree of polymerization (DP) = 5, 10 and 15) exhibited a protein loading efficiency of 60%-72% and glutathione-responsive protein release. Saporin-loaded GE11-CPs had a size of 36 - 62 nm depending on GE11 densities and DP of PAsp. Notably, GE11-CPs with 10% GE11 revealed greatly enhanced uptake in SMMC-7721 cells, boosting the anticancer potency of saporin for over 3-folds compared with non-targeted control (half-maximal inhibitory concentration (IC₅₀) = 11.0 versus 36.3 nM). The biodistribution studies using Cy5-labeled cytochrome C as a model protein demonstrated about 3-fold higher accumulation of GE11-CPs formulation than CPs counterpart in both subcutaneous and orthotopic SMMC-7721 tumor models. Notably, saporin-loaded GE11-CPs revealed low toxicity, effective tumor inhibition and significant improvement of survival rate compared with PBS and non-targeted groups (median survival time: 99 versus 37 and 42 days). EGFR-targeted chimaeric polymersomes carrying proteins appear an interesting HCC treatment modality.

Identification of a peptide targeting CD56

Neural cell adhesion molecule 1 (NCAM1/CD56) is expressed on immune cells, myoblasts, and malignant cells, and there is a growing demand for the genetic detection of CD56 and CD56-targeted therapy. In the present study, we developed a novel peptide ligand (designated Natein) that binds to human CD56 by using T7 phage display technology. Natein recognized the extracellular region of CD56 and could bind to natural killer (NK) cells and CD56-positive (CD56⁺) cancer cells. CD56⁺ cells enriched from human peripheral blood mononuclear cells (PBMCs) using biotinylated Natein-conjugated microbeads, similarly to CD56 antibody-isolated cells, demonstrated functional cytotoxicity against K562 cells. In addition, Natein could be used to stain CD56⁺ lymphoma cells in nasal-type extranodal NK/T-cell lymphoma tissues similarly to a CD56 antibody. These findings suggest that Natein has the potential to be alternative to CD56 antibody that could be used for peptide-based cell isolation and diagnosis.

Peptide-Drug Conjugates and Their Targets in Advanced Cancer Therapies

Cancer became recently the leading cause of death in industrialized countries. Even though standard treatments achieve significant effects in growth inhibition and tumor elimination, they cause severe side effects as most of the applied drugs exhibit only minor selectivity for the malignant tissue. Hence, specific addressing of tumor cells without affecting healthy tissue is currently a major desire in cancer therapy. Cell surface receptors, which bind peptides are frequently overexpressed on cancer cells and can therefore be considered as promising targets for selective tumor therapy. In this review, the benefits of peptides as tumor homing agents are presented and an overview of the most commonly addressed peptide receptors is given. A special focus was set on the bombesin receptor family and the neuropeptide Y receptor family. In the second part, the specific requirements of peptide-drug conjugates (PDC) and intelligent linker structures as an essential component of PDC are outlined. Furthermore, different drug cargos are presented including classical and recent toxic agents as well as radionuclides for diagnostic and therapeutic approaches. In the last part, boron neutron capture therapy as advanced targeted cancer therapy is introduced and past and recent developments are reviewed.

Organ-restricted vascular delivery of nanoparticles for lung cancer therapy

Nanoparticle-based targeted drug delivery holds promise for treatment of cancers. However, most approaches fail to be translated into clinical success due to ineffective tumor targeting in vivo. Here, the delivery potential of mesoporous silica nanoparticles (MSN) functionalized with targeting ligands for EGFR and CCR2 is explored in lung tumors. The addition of active targeting ligands on MSNs enhances their uptake in vitro but fails to promote specific delivery to tumors in vivo, when administered systemically via the blood or locally to the lung into immunocompetent murine lung cancer models. Ineffective tumor targeting is due to efficient clearance of the MSNs by the phagocytic cells of the liver, spleen, and lung. These limitations, however, are successfully overcome using a novel organ-restricted vascular delivery (ORVD) approach. ORVD in isolated and perfused mouse lungs of Kras-mutant mice enables effective nanoparticle extravasation from the tumor vasculature into the core of solid lung tumors. In this study, ORVD promotes tumor cell-specific uptake of nanoparticles at cellular resolution independent of their functionalization with targeting ligands. Organ-restricted vascular delivery thus opens new avenues for optimized nanoparticles for lung cancer therapy and may have broad applications for other vascularized tumor types.

Amphiphilic drug-peptide-polymer conjugates based on poly(ethylene glycol) and hyperbranched polyglycerol for epidermal growth factor receptor targeting: the effect of conjugate aggregation on in vitro activity

Numerous peptide-drug conjugates have been developed over the years to enhance the specificity and selectivity of chemotherapeutic agents for tumour cells. In our present work, epidermal growth factor receptor targeting drug-peptide conjugates were prepared using GE11 and D4 peptides. To ensure the drug release, the cathepsin B labile GFLG spacer was incorporated between the targeting peptide and the drug molecule (daunomycin), which significantly increased the hydrophobicity and thereby decreased the water solubility of the conjugates. To overcome the solubility problem, drug-peptide-polymer conjugates with systematic structural variations were prepared, by linking poly(ethylene glycol) (PEG) or a well-defined amino-monofunctional hyperbranched polyglycerol (HbPG) directly or via a pentaglycine spacer to the targeting peptides. All the drug-peptide-polymer conjugates were water-soluble as confirmed by turbidimetric measurements. The results of the in vitro cell viability and cellular uptake measurements on HT-29 human colon adenocarcinoma cells proved that the HbPG and the PEG highly influenced the biological activity. The conjugation of the hydrophilic polymer resulted in the amphiphilic character of the conjugates, which led to self-aggregation and nanoparticle formation that decreased the cellular uptake above a specific aggregation concentration. On the other hand, the hydrodynamic volume and the different polymer chain topology of the linear PEG and the compact hyperbranched HbPG also played an important role in the biological activity. Therefore, in similar systems, the investigation of the colloidal properties is inevitable for the better understanding of the biological activity, which can reveal the structure-activity relationship of amphiphilic drug-peptide-polymer conjugates for efficient tumour targeting.

Particle-Size-Dependent Delivery of Antitumoral miRNA Using Targeted Mesoporous Silica Nanoparticles

Multifunctional core-shell mesoporous silica nanoparticles (MSN) were tailored in size ranging from 60 to 160 nm as delivery agents for antitumoral microRNA (miRNA). The positively charged particle core with a pore diameter of about 5 nm and a stellate pore morphology allowed for an internal, protective adsorption of the fragile miRNA cargo. A negatively charged particle surface enabled the association of a deliberately designed block copolymer with the MSN shell by charge-matching, simultaneously acting as a capping as well as endosomal release agent. Furthermore, the copolymer was functionalized with the peptide ligand GE11 targeting the epidermal growth factor receptor, EGFR. These multifunctional nanoparticles showed an enhanced uptake into EGFR-overexpressing T24 bladder cancer cells through receptor-mediated cellular internalization. A luciferase gene knock-down of up to 65% and additional antitumoral effects such as a decreased cell migration as well as changes in cell cycle were observed. We demonstrate that nanoparticles with a diameter of 160 nm show the fastest cellular internalization after a very short incubation time of 45 min and produce the highest level of gene knock-down.

Membrane Trafficking and Subcellular Drug Targeting Pathways

The movement of micro and macro molecules into and within a cell significantly governs several of their pharmacokinetic and pharmacodynamic parameters, thus regulating the cellular response to exogenous and endogenous stimuli. Trafficking of various pharmacological agents and other bioactive molecules throughout and within the cell is necessary for the fidelity of the cells but has been poorly investigated. Novel strategies against cancer and microbial infections need a deeper understanding of membrane as well as subcellular trafficking pathways and essentially regulate several aspects of the initiation and spread of anti-microbial and anti-cancer drug resistance. Furthermore, in order to avail the maximum possible bioavailability and therapeutic efficacy and to restrict the unwanted toxicity of pharmacological bioactives, these sometimes need to be functionalized with targeting ligands to regulate the subcellular trafficking and to enhance the localization. In the recent past the scenario drug targeting has primarily focused on targeting tissue components and cell vicinities, however, it is the membranous and subcellular trafficking system that directs the molecules to plausible locations. The effectiveness of the delivery platforms largely depends on their physicochemical nature, intracellular barriers, and biodistribution of the drugs, pharmacokinetics and pharmacodynamic paradigms. Most subcellular organelles possess some peculiar characteristics by which membranous and subcellular targeting can be manipulated, such as negative transmembrane potential in mitochondria, intraluminal delta pH in a lysosome, and many others. Many specialized methods, which positively promote the subcellular targeting and restrict the off-targeting of the bioactive molecules, exist. Recent advancements in designing the carrier molecules enable the handling of membrane trafficking to facilitate the delivery of active compounds to subcellular localizations. This review aims to cover membrane trafficking pathways which promote the delivery of the active molecule in to the subcellular locations, the associated pathways of the subcellular drug delivery system, and the role of the carrier system in drug delivery techniques.

Constructing a better binding peptide for drug delivery targeting the interleukin-4 receptor

Targeted delivery of antitumor drugs is especially important for tumour therapy. Tumour targeting peptides have been shown to be very effective drug carriers for tumour therapy. Interleukin-4 receptor (IL-4R) is overexpressed on the surface of various human solid tumours. To obtain a better targeting peptide, we first designed a novel targeting peptide derived from interleukin-4 (IL-4), ILBP-b. ILBP-b contains the key high-affinity binding residue E9 of IL-4 to IL-4R. Compared with a reported targeting peptide ILBP-a (containing another key high affinity residue R88), ILBP-b was proved to be a better targeting peptide by the fluorescence experiments. Then, we further fused ILBP-b and ILBP-a to increase the multisite-binding ability of ILBP-b and got a better targeting peptide ILBP-ba. ILBP-ba showed a stronger preferential binding ability to IL-4R high-expressing cells than ILBP-a and ILBP-b. Competitive binding experiments demonstrated ILBP-ba specifically targets IL-4R. By fusing ILBP-ba with drug protein trichosanthin (TCS), in vitro drug carrying experiments showed that ILBP-ba could specifically enhance the killing effect of TCS on IL-4R high-expressing tumour cells (more than 10 folds). These results indicated that ILBP-ba has great potential for drug delivery applications targeting IL-4R and will be beneficial for the development of tumour therapeutic agents.

Targeting EGFR Overexpression at the Surface of Colorectal Cancer Cells by Exploiting Amidated BODIPY-Peptide Conjugates

Three BODIPY-peptide conjugates designed to target the epidermal growth factor receptor (EGFR) at the extracellular domain were synthesized, and their specificity for binding to EGFR was investigated. Peptide sequences containing seven amino acids, GLARLLT (2) and KLARLLT (4), and 13 amino acids, GYHWYGYTPQNVI (3), were conjugated to carboxyl BODIPY dye (1) by amide bond formation in up to 73% yields. The BODIPY-peptide conjugates and their "parent" peptides were determined to bind to EGFR experimentally using SPR analysis and were further investigated using computational methods (AutoDock). Results of SPR, competitive binding and docking studies propose that conjugate 6 including the GYHWYGYTPQNVI sequence binds to EGFR more effectively than conjugates 5 and 7, bearing the smaller peptide sequences. Findings in human carcinoma HEp2 cells overexpressing EGFR showed nontoxic behavior in the presence of activated light (1.5 J cm^-2 ) and in the absence of light for all BODIPYs. Furthermore, conjugate 6 showed about five-fold higher accumulation within HEp2 cells compared with conjugates 5 and 7, localizing preferentially in the cell ER and lysosomes. Our findings suggest that BODIPY-peptide conjugate 6 is a promising contrast agent for detection of colorectal cancer and potentially other EGFR-overexpressing cancers.

Tissue-Specific Delivery of Oligonucleotides

From the initial discovery of short-interfering RNA (siRNA) and antisense oligonucleotides for specific gene knockdown at the posttranscriptional level to the current CRISPR-Cas9 system offering gene editing at the genomic level, oligonucleotides, in addition to their biological functions in storing and conveying genetic information, provide the most prominent solutions to targeted gene therapies. Nonetheless, looking into the future of curing cancer and acute diseases, researchers are only cautiously optimistic as the cellular delivery of these polyanionic biomacromolecules is still the biggest hurdle for their therapeutic realization. To overcome the delivery obstacle, oligonucleotides have been encapsulated within or conjugated with delivery vehicles for enhanced membrane penetration, improved payload, and tissue-specific delivery. Such delivery systems include but not limited to virus-based vehicles, gold-nanoparticle vehicles, formulated liposomes, and synthetic polymers. In this chapter, delivery challenges imposed by biological barriers are briefly discussed; followed by recent advances in tissue-specific oligonucleotide delivery utilizing both viral and nonviral delivery vectors, discussing their advantages, and how judicious design and formulation could improve and expand their potential as delivery vehicles.

Targeting drug delivery system for platinum(Ⅳ)-Based antitumor complexes

Classical platinum(II) anticancer agents are widely-used chemotherapeutic drugs in the clinic against a range of cancers. However, severe systemic toxicity and drug resistance have become the main obstacles which limit their application and effectiveness. Because divalent cisplatin analogues are easily destroyed in vivo, their bioavailability is low and no selective to tumor tissues. The platinum(IV) prodrugs are attractive compounds for cancer treatment because they have great advantages, e.g., higher stability in biological media, aqueous solubility and no cross-resistance with cisplatin, which may become the next generation of platinum anticancer drugs. In addition, platinum(IV) drugs could be taken orally, which could be more acceptable to cancer patients, breaking the current situation that platinum(II) drugs can only be given by injection. The coupling of platinum(IV) complexes with tumor targeting groups avoids the disadvantages such as instability in blood, irreversible binding to plasma proteins, rapid renal clearance, and non-specific distribution in normal tissues. Because of the above advantages, the combination of platinum complexes and tumor targeting groups has become the hottest field in the research and development of new platinum drugs. These approaches can be roughly categorized into two groups: active and passive targeted strategies. This review concentrates on various targeting and delivery strategies for platinum(IV) complexes to improve the efficacy and reduce the side effects of platinum-based anticancer drugs. We have made a summary of the related articles on platinum(IV) targeted delivery in recent years. We believe the results of the studies described in this review will provide new ideas and strategies for the development of platinum drugs.

Hypoxia-responsive folic acid conjugated glycol chitosan nanoparticle for enhanced tumor targeting treatment

Hypoxia is a characteristic feature of various ischemic diseases, including cancer. This study describes the development of glycol chitosan nanoparticles, hydrophobically modified with 4-nitrobenzyl chloroformate and folic acid (FA), that can specifically release drugs under hypoxic conditions. This hypoxia-responsive glycol chitosan nanoparticle conjugated with FA (HRGF) possesses tumor-targeting properties by virtue of conjugated FA and is able to release drugs in a nitroreductase (NTR)-dependent manner because its structure is cleaved by NTR under hypoxic conditions. HRGF nanoparticles showed improved in vivo cancer-targeting ability compared with HRG nanoparticles without FA. In vitro drug release profiles revealed that doxorubicin (DOX)-loaded HRGF (D@HRGF) nanoparticles showed rapid release under hypoxia conditions than normoxic conditions. In vitro cytotoxicity tests and microscopic observations showed that D@HRGF nanoparticles were more toxic towards hypoxic cells than normoxic cells, and that the release of DOX was more effective in hypoxia than normoxia. In vivo, D@HRGF nanoparticles showed more effective antitumor activity in mice compared with D@HRG and free DOX. Collectively, these results show that HRGF nanoparticles function as an effective drug-delivery system in hypoxic conditions. Moreover, these hypoxia-responsive nanoparticles would be effective not only in cancer, but also in other ischemic diseases.

Phage nanofibers in nanomedicine: Biopanning for early diagnosis, targeted therapy, and proteomics analysis

Display of a peptide or protein of interest on the filamentous phage (also known as bacteriophage), a biological nanofiber, has opened a new route for disease diagnosis and therapy as well as proteomics. Earlier phage display was widely used in protein-protein or antigen-antibody studies. In recent years, its application in nanomedicine is becoming increasingly popular and encouraging. We aim to review the current status in this research direction. For better understanding, we start with a brief introduction of basic biology and structure of the filamentous phage. We present the principle of phage display and library construction method on the basis of the filamentous phage. We summarize the use of the phage displayed peptide library for selecting peptides with high affinity against cells or tissues. We then review the recent applications of the selected cell or tissue targeting peptides in developing new targeting probes and therapeutics to advance the early diagnosis and targeted therapy of different diseases in nanomedicine. We also discuss the integration of antibody phage display and modern proteomics in discovering new biomarkers or target proteins for disease diagnosis and therapy. Finally, we propose an outlook for further advancing the potential impact of phage display on future nanomedicine. This article is categorized under: Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.

Reimaging biological barriers affecting distribution and extravasation of PEG/peptide- modified liposomes in xenograft SMMC7721 tumor

Liposomes, as one of the most successful nanotherapeutics, have a major impact on many biomedical areas. In this study, we performed laser scanning confocal microscope (LSCM) and immunohistochemistry (IHC) assays to investigate the intra-tumor transport and antitumor mechanism of GE11 peptide-conjugated active targeting liposomes (GE11-TLs) in SMMC7721 xenograft model. According to classification of individual cell types in high resolution images, biodistribution of macrophages, tumor cells, cells with high epidermal growth factor receptor (EGFR) expression and interstitial matrix in tumor microenvironment, in addition, their impacts on intra-tumor penetration of GE11-TLs were estimated. Type I collagen fibers and macrophage flooded in the whole SMMC7721 tumor xenografts. Tumor angiogenesis was of great heterogeneity from the periphery to the center region. However, the receptor-binding site barriers were supposed to be the leading cause of poor penetration of GE11-TLs. We anticipate these images can give a deep reconsideration for rational design of target nanoparticles for overcoming biological barriers to drug delivery.

Polymer-mediated gene therapy: Recent advances and merging of delivery techniques

The ability to safely and precisely deliver genetic materials to target sites in complex biological environments is vital to the success of gene therapy. Numerous viral and nonviral vectors have been developed and evaluated for their safety and efficacy. This study will feature progress in synthetic polymers as nonviral vectors, which benefit from their chemical versatility, biocompatibility, and ability to carry both therapeutic cargo and targeting moieties. The combination of synthetic gene carrying constructs with advanced delivery techniques promises new therapeutic options for treating and curing genetic disorders. This article is characterized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Research Progress Evaluating the Function and Mechanism of Anti-Tumor Peptides

Malignant tumors cause a high mortality rate worldwide, and they severely threaten human health and negatively affect the economy. Despite the advancements in tumor-related molecular genetics and effective new processes in anti-tumor drug development, the anti-tumor drugs currently used in clinical practice are inadequate due to their poor efficacy or severe side effects. Therefore, developing new safe and efficient drugs is a top priority for curing cancer. The peptide has become a suitable agent due to its exact molecular weight between whole protein and small molecule, and it has high targeting ability, high penetrability, low immunogenicity, and is convenient to synthesize and easy to modify. Because of these advantages, peptides have excellent prospect for application as anti-tumor agents. This article reviews the recent research progress evaluating anti-tumor peptides and their anti-tumor mechanisms, and may act as a reference for the future development and clinical application of anti-tumor peptides.

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Targeting strategies for superparamagnetic iron oxide nanoparticles in cancer therapy

Among various nanoparticles, superparamagnetic iron oxide nanoparticles (SPIONs) have been increasingly studied for their excellent superparamagnetism, magnetic heating properties, and enhanced magnetic resonance imaging (MRI). The conjugation of SPIONs with drugs to obtain delivery nanosystems has several advantages including magnetic targeted functionalization, in vivo imaging, magnetic thermotherapy, and combined delivery of anticancer agents. To further increase the targeting efficiency of drugs through a delivery nanosystem based on SPIONs, additional targeting moieties including transferrin, antibodies, aptamers, hyaluronic acid, folate, and targeting peptides are coated onto the surface of SPIONs. Therefore, this review summarizes the latest progresses in the conjugation of targeting molecules and drug delivery nanosystems based on SPIONs, especially focusing on their performances to develop efficient targeted drug delivery systems for tumor therapy. STATEMENT OF SIGNIFICANCE: Some magnetic nanoparticle-based nanocarriers loaded with drugs were evaluated in patients and did not produce convincing results, leading to termination of clinical development in phase II/III. An alternative strategy for drug delivery systems based on SPIONs is the conjugation of these systems with targeting segments such as transferrin, antibodies, aptamers, hyaluronic acid, folate, and targeting peptides. These targeting moieties can be recognized by specific integrin/receptors that are overexpressed specifically on the tumor cell surface, resulting in minimizing dosage and reducing off-target effects. This review focuses on magnetic nanoparticle-based nonviral drug delivery systems with targeting moieties to deliver anticancer drugs, with an aim to provide suggestions on the development of SPIONs through discussion.

Methods for loading therapeutics into extracellular vesicles and generating extracellular vesicles mimetic-nanovesicles

Extracellular vesicles (EVs) are membrane bound vesicles released into the extracellular environment by eukaryotic and prokaryotic cells. EVs are enriched in active biomolecules and they can horizontally transfer cargo to recipient cells. In recent years EVs have demonstrated promising clinical applications due to their theragnostic potential. Although EVs have promising therapeutic potential, there are several challenges associated with using EVs before transition from the laboratory to clinical use. Some of these challenges include issues around low yield, isolation and purification methodologies, and efficient engineering (loading) of EVs with therapeutic cargo. Also, to achieve higher therapeutic efficiency, EV architecture and cargo may need to be manipulated prior to clinical application. Some of these issues have been addressed by developing biomimetic EVs. EV mimetic-nanovesicles (M-NVs) are a type of artificial EVs which can be generated from all cell types with comparable characteristics as EVs for an alternative therapeutic modality. In this review, we will discuss current techniques for modifying EVs and methodology used to generate and customize EV mimetic-nanovesicles.

Multi-functional self-assembled nanoparticles for pVEGF-shRNA loading and anti-tumor targeted therapy

Although RNA interference (RNAi) technology shows great potential in cancer treatment, the tumor target delivery and sufficient cytosolic transport of RNAi agents are still the main obstacles for its clinical applications. Herein, we report a functional supramolecular self-assembled nanoparticle vector for RNAi agent loading and tumor target therapy. Molecular block adamantane-grafted poly(ethylene glycol) (Ad-PEG) was modified with epidermal growth factor receptor (EGFR)-specific binding ligand GE11 or pH-sensitive fusogenic peptide GALA and then used for self-assembly with cyclodextrin-grafted branched polyethylenimine (CD-PEI), adamantane-grafted polyamidoamine dendrimer (Ad-PAMAM), and plasmid DNA containing a small hairpin RNA expression cassette against vascular endothelial growth factor (VEGF) into functional DNA-loaded supramolecular nanoparticles (GE11&GALA-pshVEGF@SNPs) based on molecular recognition and charge interaction. These functional peptides facilitated the target cell binding, internalization, and endosomal escape of GE11&GALA-pshVEGF@SNPs, resulting in increased reporter gene expression and efficient targeted gene silencing. The systemic delivery of the GE11&GALA-pshVEGF@SNPs can efficiently downregulate the intratumoral VEGF protein levels, reduce blood vessel formation, and significantly inhibit A549 xenograft tumor growth. These results reveal the potential of these multifunctional self-assembled nanoparticles as a nucleic acid drug delivery system for the treatment of lung cancer.

Peptide carriers to the rescue: overcoming the barriers to siRNA delivery for cancer treatment

Cancer is a significant health concern worldwide and its clinical treatment presents many challenges. Consequently, much research effort has focused on the development of new anticancer drugs to combat this disease. One area of exploration, in particular, has been in the therapeutic application of RNA interference (RNAi). Although RNAi appears to be an attractive therapeutic tool for the treatment of cancer, one of the primary obstacles towards its pervasive use in the clinic has been cell/tissue type-specific cytosolic delivery of therapeutic small interfering RNA (siRNA) molecules. Consequently, varied drug delivery platforms have been developed and widely explored for siRNA delivery. Among these candidate drug delivery systems, peptides have shown great promise as siRNA carriers due to their varied physiochemical properties and functions, simple formulations, and flexibility in design. In this review, we will focus on distinguishing between the different classes of peptide carriers based on their functions, as well as summarize and discuss the various design strategies and advancements that have been made in circumventing the barriers to siRNA delivery for cancer treatment. Resolution of these challenges by peptide carriers will accelerate the translation of RNAi-based therapies to the clinic.

Phage display screening of therapeutic peptide for cancer targeting and therapy

Recently, phage display technology has been announced as the recipient of Nobel Prize in Chemistry 2018. Phage display technique allows high affinity target-binding peptides to be selected from a complex mixture pool of billions of displayed peptides on phage in a combinatorial library and could be further enriched through the biopanning process; proving to be a powerful technique in the screening of peptide with high affinity and selectivity. In this review, we will first discuss the modifications in phage display techniques used to isolate various cancer-specific ligands by in situ, in vitro, in vivo, and ex vivo screening methods. We will then discuss prominent examples of solid tumor targeting-peptides; namely peptide targeting tumor vasculature, tumor microenvironment (TME) and over-expressed receptors on cancer cells identified through phage display screening. We will also discuss the current challenges and future outlook for targeting peptide-based therapeutics in the clinics.

Development of EGFR-targeted evodiamine nanoparticles for the treatment of colorectal cancer

Invasion and metastasis of colorectal cancer (CRC) are leading causes of death of CRC patients. Previous findings demonstrate that evodiamine (Evo), an indolequinone alkaloid, is effective in combating CRC; however, its poor aqueous solubility and low oral bioavailability limit its application in the prevention of invasion and metastasis of CRC. It is known that selectively targeting cancer-specific receptors highly expressed on the surface of cancer cells by nanocarriers loaded with cytotoxic drugs is a viable strategy in nanobiotechnology to enhance cancer cell killing and minimize side effects. In this study, we report the development of a new class of nanotherapeutics: EGFR-targeting Evo-encapsulated poly(amino acid) nanoparticles (GE11-Evo-NPs). These nanoparticles exhibited good aqueous solubility, slow release, and active targeting capability. Their inhibitory effect on human colon cancer cells and therapeutic efficacy against invasion and metastasis of CRC in nude mice were systematically investigated. Mechanisms of the GE11-Evo-NPs against EGFR mediated invasion and metastasis of CRC were also explored. Compared with free Evo, the GE11-Evo-NPs showed significantly increased cytotoxicity to colon cancer cells and potently inhibited CRC LoVo cell adhesion, invasion, and migration. The expression of EGFR, VEGF, and MMP proteins was dramatically down-regulated, which may partially account for their inhibition of invasion and metastasis of CRC. Moreover, in vivo studies show that the GE11-Evo-NPs exhibited much greater potency than other control groups in inhibiting CRC invasion and metastasis, tumor volume, and growth in nude mice, leading to a significantly prolonged tumor-bearing survival duration (P < 0.01).

Nanomedicine as a putative approach for active targeting of hepatocellular carcinoma

The effectiveness of chemotherapy in hepatocellular carcinoma (HCC) is restricted by chemo-resistance and systemic side effects. To improve the efficacy and safety of chemotherapeutics in HCC management, scientists have attempted to deliver these drugs to malignant tissues using targeted carriers as nanoparticles (NPs). Among the three types of NPs targeting (active, passive, and stimuli-responsive), active targeting is the most commonly investigated in HCC treatment. Despite the observed promising results so far, clinical research on nanomedicine targeting for HCC treatment still faces many challenges.These include batch-to-batch physicochemical properties' variations, limiting large scale production and insufficient data on human and environmental toxicities. This review summarized the characteristics of different nanocarriers, ligands, targeted receptors on HCC cells and provided recommendations to overcome the challenges, facing this novel line of treatment for HCC.

HIF1α-siRNA and gemcitabine combination-based GE-11 peptide antibody-targeted nanomedicine for enhanced therapeutic efficacy in pancreatic cancers

Pancreatic cancer is one of the deadliest cancers across the world with an average 5-year survival rate of less than <6%. In this study, gemcitabine (GEM) and HIF1α-siRNA loaded GE-11 peptide conjugated liposome was successfully prepared and evaluated for its antitumor efficacy in pancreatic cancer cells. The GE11 increased the targeting specificity of liposome carrier and increased the intracellular concentrations in the cancer cells. Furthermore, synergistic combination of GEM and HIF1a-siRNA exhibited remarkable improvement in the declining of cancer cell proliferations. siRNA could effectively decrease the expression of HIF1a gene in the cancer cells. Importantly, GE-11 peptide-conjugated GEM/siRNA-loaded liposomes (GE-GML/siRNA) increased the total amount of apoptosis cells with higher proportion of cells in late apoptosis phase. GE-GML induced remarkable apoptosis of cancer cells and induced chromatin condensation and nuclear fragmentation which are considered to be typical features of apoptosis and cell death. GE-GML/siRNA showed a significant reduction in the tumour burden suggesting the superior anticancer efficacy of this formulation. GE-GML/siRNA showed four-fold reduction in tumour compared to control and two-fold reduction compared to GE-GML, respectively. Overall, present work lays foundation for the combination of GEM and HIF1a-siRNA loaded in a targeted nanocarrier system as a unique therapeutic option in pancreatic cancer treatment.

Synthesis and biological evaluation of an epidermal growth factor receptor-targeted peptide-conjugated phthalocyanine-based photosensitiser

A peptide-conjugated zinc(ii) phthalocyanine containing the epidermal growth factor receptor-targeted heptapeptide QRHKPRE has been prepared. The conjugate labelled as ZnPc-QRH* can selectively bind to the cell membrane of HT29 human colorectal adenocarcinoma cells in 10 min followed by internalisation upon prolonged incubation via receptor-mediated endocytosis, leading to localisation in lysosomes eventually. By manipulating the incubation time, the subcellular localisation of the conjugate can be varied and the cell-death pathways induced upon irradiation can also be altered. It has been found that photosensitisation initiated at the cell membrane and in the lysosomes would trigger cell death mainly through necrosis and apoptosis respectively. Intravenous administration of the conjugate into HT29 tumour-bearing nude mice resulted in higher accumulation in the tumour than in most major organs. The selective binding of this conjugate to tumour has also been demonstrated by comparing the results with those of the analogue with a scrambled peptide sequence (EPRQRHK). The overall results indicate that ZnPc-QRH* is a promising EGFR-targeted photosensitiser for photodynamic therapy.

Synthetic peptide-labelled micelles for active targeting of cells overexpressing EGF receptors

The goal of nanomedicine is to transport drugs to pathological tissues, reducing side effects while increasing targeting and efficacy. Aggregates grafted by bioactive molecules act as the active targeting agents. Among bioactive molecules, peptides, which are able to recognize overexpressed receptors on cancer cell membranes, appear to be very promising. The aim of this study was to formulate analog peptide-labeled micelles enabled to potentially deliver highly hydrophobic drugs to cancer cells overexpressing epidermal growth factor (EGF) receptor (EGFR). The selected synthetic peptide sequences were anchored to a hydrophobic moiety, aiming to obtain amphiphilic peptide molecules. Mixed micelles were formulated with Pluronic^® F127. These micelles were fully characterized by physico-chemical methods, estimating the critical micellar concentration (CMC) by fluorescence. Their sizes were established by dynamic light scattering (DLS) analysis. Then, micelles were also tested in vitro for their binding capacity to human hepatocellular carcinoma (HCC) cell lines overexpressing EGFR.

Understanding the good and poor cell targeting activity of gold nanostructures functionalized with molecular units for the epidermal growth factor receptor

Nanostructures can strongly interact with cells or other biological structures; furthermore when they are functionalized with targeting units, they are of great interest for a variety of applications in the biotechnology field like those for efficient imaging, diagnosis and therapy and in particular for cancer theranostics. Obtaining targeting with good specificity and sensitivity is a key necessity, which, however, is affected by the complexity of the interactions between the nanostructures and the biological components. In this work we report the study of specificity and sensitivity of gold nanoparticles functionalized with the peptide GE11 for the targeting of the epidermal growth factor receptor, expressed on many cells and, in particular, on many types of cancer cells. We show how a combination of spectroscopic measurements and molecular dynamics simulations allows the comprehension of the targeting activity of peptides linked to the surface of gold nanostructures and how the targeting is tuned by the presence of polyethylene glycol chains.

Using Self-Assembling Peptides to Integrate Biomolecules into Functional Supramolecular Biomaterials

Throughout nature, self-assembly gives rise to functional supramolecular biomaterials that can perform complex tasks with extraordinary efficiency and specificity. Inspired by these examples, self-assembly is increasingly used to fabricate synthetic supramolecular biomaterials for diverse applications in biomedicine and biotechnology. Peptides are particularly attractive as building blocks for these materials because they are based on naturally derived amino acids that are biocompatible and biodegradable; they can be synthesized using scalable and cost-effective methods, and their sequence can be tailored to encode formation of diverse architectures. To endow synthetic supramolecular biomaterials with functional capabilities, it is now commonplace to conjugate self-assembling building blocks to molecules having a desired functional property, such as selective recognition of a cell surface receptor or soluble protein, antigenicity, or enzymatic activity. This review surveys recent advances in using self-assembling peptides as handles to incorporate biologically active molecules into supramolecular biomaterials. Particular emphasis is placed on examples of functional nanofibers, nanovesicles, and other nano-scale structures that are fabricated by linking self-assembling peptides to proteins and carbohydrates. Collectively, this review highlights the enormous potential of these approaches to create supramolecular biomaterials with sophisticated functional capabilities that can be finely tuned to meet the needs of downstream applications.

Enhanced antiproliferative effect of resveratrol in head and neck squamous cell carcinoma using GE11 peptide conjugated liposome

The present study describes the preparation of a dodecapeptide YHWYGYTPQNVI (GE11)‑conjugated liposome bound with polyethylene glycol to enhance the therapeutic effect of resveratrol (RSV) in head and neck cancer cells. The results indicated that (RSV)‑loaded GE11‑conjugated liposomes (RSV‑GL) exhibited a high entrapment efficiency of >95%, with an active drug loading level of 19.5% w/w. Release kinetics revealed that RSV was released in a slow and sustained manner from the RSV‑GL and RSV‑loaded liposome (RSV‑L) nanoparticulate systems. The epidermal growth factor receptor (EGFR)‑overexpressing squamous cell carcinoma HN cells specifically internalized GE11 surface‑conjugated liposome in a manner that was markedly increased compared with that of the non‑targeted carrier. Consistently, RSV‑GL exhibited a significantly increased cytotoxic effect compared with that of the non‑targeted nanoparticles. Notably, RSV‑GL induced significantly increased proportions of early (~60%) and late (~10%) apoptotic cells in head and neck cancer cell populations. To the best of our knowledge, the application and development of EGFR‑targeted peptide‑conjugated liposome system for RSV delivery has not been studied previously in the treatment of head and neck cancer. In addition, RSV‑GL exhibited the greatest antitumor efficacy compared with any other group. RSV‑GL exhibited a 2‑fold decrease in tumor volume compared with the free RSV and a 3‑fold decrease in volume compared with the control. Overall, the nanomedicine strategy described in the present study may potentially advance the chemotherapy‑based treatment of head and neck cancer, with promising applications in other EGFR‑overexpressing tumors.

Synthesis, Characterization, and Evaluation of Near-IR Boron Dipyrromethene Bioconjugates for Labeling of Adenocarcinomas by Selectively Targeting the Epidermal Growth Factor Receptor

A series of five boron dipyrromethene (BODIPY) bioconjugates containing an epidermal growth factor receptor (EGFR)-targeted pegylated LARLLT peptide and/or a glucose or biotin ethylene diamine group were synthesized, and the binding capability of the new conjugates to the extracellular domain of EGFR was investigated using molecular modeling, surface plasmon resonance, fluorescence microscopy, competitive binding assays, and animal studies. The BODIPY conjugates with a LARLLT peptide were found to bind specifically to EGFR, whereas those lacking the peptide bound weakly and nonspecifically. All BODIPY conjugates showed low cytotoxicity (IC₅₀ > 94 μM) in HT-29 cells, both in the dark and upon light activation (1.5 J/cm²). Studies of nude mice bearing subcutaneous human HT-29 xenografts revealed that only BODIPY conjugates bearing the LARLLT peptide showed tumor localization 24 h after intravenous administration. The results of our studies demonstrate that BODIPY bioconjugates bearing the EGFR-targeting peptide 3PEG-LARLLT show promise as near-IR fluorescent imaging agents for colon cancers overexpressing EGFR.

MicroRNA Shuttle from Cell-To-Cell by Exosomes and Its Impact in Cancer

The identification of exosomes, their link to multivesicular bodies and their potential role as a messenger vehicle between cancer and healthy cells opens up a new approach to the study of intercellular signaling. Furthermore, the fact that their main cargo is likely to be microRNAs (miRNAs) provides the possibility of the transfer of such molecules to control activities in the recipient cells. This review concerns a brief overview of the biogenesis of both exosomes and miRNAs together with the movement of such structures between cells. The possible roles of miRNAs in the development and progression of breast, ovarian and prostate cancers are discussed.

Synthesis, Microtubule-Binding Affinity, and Antiproliferative Activity of New Epothilone Analogs and of an EGFR-Targeted Epothilone-Peptide Conjugate

A new simplified, epoxide-free epothilone analog was prepared incorporating an N-(2-hydroxyethyl)-benzimidazole side chain, which binds to microtubules with high affinity and inhibits cancer cell growth in vitro with nM potency. Building on this scaffold, a disulfide-linked conjugate with the purported EGFR-binding (EGFR, epidermal growth factor receptor) peptide GE11 was then prepared. The conjugate retained significant microtubule-binding affinity, in spite of the size of the peptide attached to the benzimidazole side chain. The antiproliferative activity of the conjugate was significantly lower than for the parent scaffold and, surprisingly, was independent of the EGFR expression status of cells. Our data indicate that the disulfide-based conjugation with the GE11 peptide is not a viable approach for effective tumor-targeting of highly potent epothilones and probably not for other cytotoxics.

Exploiting Exosomes in Cancer Liquid Biopsies and Drug Delivery

Exosomes are cell-derived nanovesicles that transfer molecular cargo from donor to recipient cells and mediate intercellular communication. Advancement in elucidating the biological capabilities and functionalities of exosomes has revealed the striking roles of exosomes as conveyors of bioactive molecules across the biological barriers. Tumor-derived exosomes hold great promise to serve as a liquid biopsy tool for cancer diagnosis and prognosis, as large quantities of exosomes are excreted by tumor cells continuously into the circulation, carrying the molecular cargo (DNA, RNA, proteins) reflective of the genetic and signaling alterations in tumor cells. Two inherent characteristics of exosomes offer important opportunities for drug delivery: their superb transcellular permeability and biocompatibility. Exosomes are uniquely capable of encapsulating a variety of payloads and deliver them to the target tissues. This review discusses the potential of tumor-derived exosomes in cancer liquid biopsies as well as the underlying mechanisms. Furthermore, the recent progress of developing exosomes as highly versatile and efficient drug carriers is also summarized.

Small Peptide Ligands for Targeting EGFR in Triple Negative Breast Cancer Cells

The efficacy of chemotherapy for cancer treatment can be increased by targeted drug delivery to the cancer cells. This is particularly important for triple negative breast cancer (TNBC) for which chemotherapy is a major form of treatment. Here we designed and screened a library of 30 peptides starting with a previously reported epidermal growth factor receptor (EGFR) targeting peptide GE11 (YHWYGYTPQNVI). A direct peptide array-whole cell binding assay, where the peptides are conjugated to a cellulose membrane, was used to identify four peptides with enhanced binding to TNBC cells. Next, the four peptides were synthesized as FITC-labelled soluble peptides to study their direct uptake by TNBC cells using flow cytometry. The results showed that peptide analogue 22 had several fold higher uptake by the TNBC cells compared to the lead peptide GE11. The specific uptake of the peptide analogue 22 was confirmed by competition experiment using pure EGF protein. Further, peptide 22 showed dose dependent uptake by the TNBC MDA-MB-231 cells (10⁵) with uptake saturating at around 2 μM peptide concentration. Thus, peptide 22 is a promising EGFR specific TNBC cell binding peptide that can be conjugated directly to a chemotherapeutic drug or to nanoparticles for targeted drug delivery to enhance the efficacy of chemotherapy for TNBC treatment.

The use of tail-anchored protein chimeras to enhance liposomal cargo delivery

Background

Liposomes are employed as drug delivery vehicles offering a beneficial pharmacokinetic/distribution mechanism for in vivo therapeutics. Therapeutic liposomes can be designed to target specific cell types through the display of epitope-specific targeting peptides on their surface. The majority of peptides are currently attached by chemical modification of lipid constituents. Here we investigate an alternative and novel method of decorating liposomes with targeting ligand, using remotely and spontaneously inserting chimeric tail-anchored membrane (TA) proteins to drug loaded liposomes.

Methods and results

An artificial TA protein chimera containing the transmembrane domain from the spontaneously inserting TA protein cytochrome b5 (Cytb5) provided a robust membrane tether for the incorporation of three different targeting moieties into preformed liposomes. The moieties investigated were the transactivator of transcription (TAT) peptide, the EGF-receptor binding sequence GE11 and the placental and tumour homing ligand CCGKRK. In all cases, TA protein insertion neither significantly altered the size of the liposomes nor reduced drug loading. The efficacy of this novel targeted delivery system was investigated using two human cell lines, HeLa M and BeWo. Short term incubation with one ligand-modified TA chimera, incorporating the TAT peptide, significantly enhanced liposomal delivery of the encapsulated carboxyfluorescein reporter.

Conclusion

The Cytb5 TA was successfully employed as a membrane anchor for the incorporation of the desired peptide ligands into a liposomal drug delivery system, with minimal loss of cargo during insertion. This approach therefore provides a viable alternative to chemical conjugation and its potential to accommodate a wider range of targeting ligands may provide an opportunity for enhancing drug delivery.

Controlled Epidermal Growth Factor Receptor Ligand Display on Cancer Suicide Enzymes via Unnatural Amino Acid Engineering for Enhanced Intracellular Delivery in Breast Cancer Cells

Proteins are ideal candidates for disease treatment because of their high specificity and potency. Despite this potential, delivery of proteins remains a significant challenge due to the intrinsic size, charge, and stability of proteins. Attempts to overcome these challenges have most commonly relied on direct conjugation of polymers and peptides to proteins via reactive groups on naturally occurring residues. While such approaches have shown some success, they allow limited control of the spacing and number of moieties coupled to proteins, which can hinder bioactivity and delivery capabilities of the therapeutic. Here, we describe a strategy to site-specifically conjugate delivery moieties to therapeutic proteins through unnatural amino acid (UAA) incorporation, in order to explore the effect of epidermal growth factor receptor (EGFR)-targeted ligand valency and spacing on internalization of proteins in EGFR-overexpressing inflammatory breast cancer (IBC) cells. Our results demonstrate the ability to enhance targeted protein delivery by tuning a small number of EGFR ligands per protein and clustering these ligands to promote multivalent ligand-receptor interactions. Furthermore, the tailorability of this simple approach was demonstrated through IBC-targeted cell death via the delivery of yeast cytosine deaminase (yCD), a prodrug converting enzyme.

Peptide-based gene delivery vectors

Gene therapy as a strategy for disease treatment requires safe and efficient gene delivery systems that encapsulate nucleic acids and deliver them to effective sites in the cell.

Distinction Between Active and Passive Targeting of Nanoparticles Dictate Their Overall Therapeutic Efficacy

The role of nanoparticles in cancer medicine is vast with debate still surrounding the distinction between therapeutic efficacy of actively targeted nanoparticles versus passively targeted systems for drug delivery. While it is commonly accepted that methodologies that result in homing a high concentration of drug loaded nanoparticles to the tumor is beneficial, the role of intracellular trafficking of these nanoparticles in dictating the overall therapeutic outcome remains unresolved. Herein we demonstrate that the therapeutic outcome of drug loaded nanoparticles is governed beyond simply enabling nanoparticle internalization in cells. Using two model polymeric nanoparticles, one decorated with the GE11 peptide for active targeting of the epidermal growth factor receptor (EGFR) and the other without, we demonstrate that EGFR mediated intracellular internalization results in an enhanced therapeutic effect compared to the nontargeted formulation. Our findings demonstrate that the intracellular destination of nanoparticles beyond its ability to internalize is an important parameter that has to be accounted for in the design of targeted drug delivery systems.

Development of lipopolyplexes for gene delivery: A comparison of the effects of differing modes of targeting peptide display on the structure and transfection activities of lipopolyplexes

The design, synthesis and formulation of non-viral gene delivery vectors is an area of renewed research interest. Amongst the most efficient non-viral gene delivery systems are lipopolyplexes, in which cationic peptides are co-formulated with plasmid DNA and lipids. One advantage of lipopolyplex vectors is that they have the potential to be targeted to specific cell types by attaching peptide targeting ligands on the surface, thus increasing both the transfection efficiency and selectivity for disease targets such as cancer cells. In this paper, we have investigated two different modes of displaying cell-specific peptide targeting ligands at the surface of lipopolyplexes. Lipopolyplexes formulated with bimodal peptides, with both receptor binding and DNA condensing sequences, were compared with lipopolyplexes with the peptide targeting ligand directly conjugated to one of the lipids. Three EGFR targeting peptide sequences were studied, together with a range of lipid formulations and maleimide lipid structures. The biophysical properties of the lipopolyplexes and their transfection efficiencies in a basal-like breast cancer cell line were investigated using plasmid DNA bearing genes for the expression of firefly luciferase and green fluorescent protein. Fluorescence quenching experiments were also used to probe the macromolecular organisation of the peptide and pDNA components of the lipopolyplexes. We demonstrated that both approaches to lipopolyplex targeting give reasonable transfection efficiencies, and the transfection efficiency of each lipopolyplex formulation is highly dependent on the sequence of the targeting peptide. To achieve maximum therapeutic efficiency, different peptide targeting sequences and lipopolyplex architectures should be investigated for each target cell type.

68Ga-labelled NOTA-RGD-GE11 peptide for dual integrin and EGFR-targeted tumour imaging

INTRODUCTION

Multiple peptide receptors are co-expressed in many types of cancers. Arg-Gly-Asp (RGD) and GE11 peptides specifically target integrin α_Vβ₃ and EGFR, respectively. Recently, we designed and synthesized a heterodimer peptide NOTA-c(RGDyK)-GE11 (NOTA-RGD-GE11). The aim of this study was to investigate the characteristics of NOTA-RGD-GE11 for dual receptor imaging.

METHODS

NOTA-RGD-GE11 heterodimer was labelled with ⁶⁸Ga. The dual receptor binding affinity was investigated by antibody competition binding assay. The in vitro and in vivo characteristics of [⁶⁸Ga]Ga-NOTA-RGD-GE11 were investigated and compared with that of monomeric peptides [⁶⁸Ga]Ga-NOTA-RGD and [⁶⁸Ga]Ga-NOTA-GE11.

RESULTS

NOTA-RGD-GE11 had binding affinities with both integrin α_Vβ₃ and EGFR. The dual receptor targeting property of [⁶⁸Ga]Ga-NOTA-RGD-GE11 was validated by blocking studies in a NCI-H292 tumour model. [⁶⁸Ga]Ga-NOTA-RGD-GE11 showed higher tumour uptake than [⁶⁸Ga]Ga-NOTA-RGD and [⁶⁸Ga]Ga-NOTA-GE11 in biodistribution and PET/CT imaging studies.

CONCLUSION

The dual receptor targeting and enhanced tumour uptake of [⁶⁸Ga]Ga-NOTA-RGD-GE11 warrant its further investigation for dual integrin α_Vβ₃ and EGFR-targeted tumour imaging.