Single chain anti-c-Met antibody conjugated nanoparticles for in vivo tumor-targeted imaging and drug delivery

Current landscape of mRNA technologies and delivery systems for new modality therapeutics

Realizing the immense clinical potential of mRNA-based drugs will require continued development of methods to safely deliver the bioactive agents with high efficiency and without triggering side effects. In this regard, lipid nanoparticles have been successfully utilized to improve mRNA delivery and protect the cargo from extracellular degradation. Encapsulation in lipid nanoparticles was an essential factor in the successful clinical application of mRNA vaccines, which conclusively demonstrated the technology's potential to yield approved medicines. In this review, we begin by describing current advances in mRNA modifications, design of novel lipids and development of lipid nanoparticle components for mRNA-based drugs. Then, we summarize key points pertaining to preclinical and clinical development of mRNA therapeutics. Finally, we cover topics related to targeted delivery systems, including endosomal escape and targeting of immune cells, tumors and organs for use with mRNA vaccines and new treatment modalities for human diseases.

Unravelling the role of tumor microenvironment responsive nanobiomaterials in spatiotemporal controlled drug delivery for lung cancer therapy

Design and development of efficient drug delivery technologies that impart site-specificity is the need of the hour for the effective treatment of lung cancer. The emergence of materials science and nanotechnology partially helped drug delivery scientists to achieve this objective. Various stimuli-responsive materials that undergo degradation at the pathological tumor microenvironment (TME) have been developed and explored for drug delivery applications using nanotechnological approaches. Nanoparticles (NPs), owing to their small size and high surface area to volume ratio, demonstrated enhanced cellular internalization, permeation, and retention at the tumor site. Such passive accumulation of stimuli-responsive materials helped to achieve spatiotemporally controlled and targeted drug delivery within the tumors. In this review, we discussed various stimuli-physical (interstitial pressure, temperature, and stiffness), chemical (pH, hypoxia, oxidative stress, and redox state), and biological (receptor expression, efflux transporters, immune cells, and their receptors or ligands)-that are characteristic to the TME. We mentioned an array of biomaterials-based nanoparticulate delivery systems that respond to these stimuli and control drug release at the TME. Further, we discussed nanoparticle-based combinatorial drug delivery strategies. Finally, we presented our perspectives on challenges related to scale-up, clinical translation, and regulatory approvals.

Fragmented antibodies in non-small cell lung cancer: A novel nano-engineered delivery system for detection and treatment of cancer

Non-small cell lung cancer (NSCLC) has a long history of defying traditional cytotoxic treatment. Significant advancements in biotechnology, cancer biology, and immunotherapy have provided new insights that have altered the landscape for the management of NSCLC, clearing the way for a new era of pharmaceuticals in the form of monoclonal antibodies and their fragments. Antibody fragments are superior to monoclonal antibodies because of their small size, which allows them to penetrate cells and tissues effectively. When combined with functional nanocarriers, antibody fragments can target cancer cells while offering improved efficacy and fewer off-target effects. We discuss current topics of interest including anti-CTLA-4 mAbs, Talactoferrin alfa (TLF), and the CYFRA 21-1 biomarker, with brief insights into its novel detection system.

Evaluation of [18F]AlF-EMP-105 for Molecular Imaging of C-Met

C-Met is a receptor tyrosine kinase that is overexpressed in a range of different cancer types, and has been identified as a potential biomarker for cancer imaging and therapy. Previously, a ⁶⁸Ga-labelled peptide, [⁶⁸Ga]Ga-EMP-100, has shown promise for imaging c-Met in renal cell carcinoma in humans. Herein, we report the synthesis and preliminary biological evaluation of an [¹⁸F]AlF-labelled analogue, [¹⁸F]AlF-EMP-105, for c-Met imaging by positron emission tomography. EMP-105 was radiolabelled using the aluminium-[¹⁸F]fluoride method with 46 ± 2% RCY and >95% RCP in 35-40 min. In vitro evaluation showed that [¹⁸F]AlF-EMP-105 has a high specificity for c-Met-expressing cells. Radioactive metabolite analysis at 5 and 30 min post-injection revealed that [¹⁸F]AlF-EMP-105 has good blood stability, but undergoes transformation-transchelation, defluorination or demetallation-in the liver and kidneys. PET imaging in non-tumour-bearing mice showed high radioactive accumulation in the kidneys, bladder and urine, demonstrating that the tracer is cleared predominantly as [¹⁸F]fluoride by the renal system. With its high specificity for c-Met expressing cells, [¹⁸F]AlF-EMP-105 shows promise as a potential diagnostic tool for imaging cancer.

Discovery of novel cMET-targeting antibody Fab drug conjugates as potential treatment for solid tumors with highly expressed cMET

BACKGROUND

Solid tumors are becoming prevalent affecting both old and young populations. Numerous solid tumors are associated with high cMET expression. The complexity of solid tumors combined with the highly interconnected nature of the cMET/HGF pathway with other cellular pathways make the pursuit of finding an effective treatment extremely challenging. The current standard of care for these malignancies is mostly small molecule-based chemotherapy. Antibody-based therapeutics as well as antibody drug conjugates are promising emerging classes against cMET-overexpressing solid tumors.

RESEARCH DESIGN AND METHODS

In this study, we described the design, synthesis, in vitro and in vivo characterization of cMET-targeting Fab drug conjugates (FDCs) as an alternative therapeutic strategy. The format is comprised of a Fab conjugated to a potent cytotoxic drug via a cleavable linker employing lysine-based and cysteine-based conjugation chemistries.

RESULTS

We found that the FDCs have potent anti-tumor efficacies in cancer cells with elevated overexpression of cMET. Moreover, they demonstrated a remarkable anti-tumor effect in a human gastric xenograft mouse model.

CONCLUSIONS

The FDC format has the potential to overcome some of the challenges presented by the other classes of therapeutics. This study highlights the promise of antibody fragment-based drug conjugate formats for the treatment of solid tumors.

Next-generation viral nanoparticles for targeted delivery of therapeutics: Fundamentals, methods, biomedical applications, and challenges

INTRODUCTION

Viral nanoparticles (VNPs) are virus-based nanocarriers that have been studied extensively and intensively for biomedical applications. However, their clinical translation is relatively low compared to the predominating lipid-based nanoparticles. Therefore, this article describes the fundamentals, challenges, and solutions of the VNP-based platform, which will leverage the development of next-generation VNPs.

AREAS COVERED

Different types of VNPs and their biomedical applications are reviewed comprehensively. Strategies and approaches for cargo loading and targeted delivery of VNPs are examined thoroughly. The latest developments in controlled release of cargoes from VNPs and their mechanisms are highlighted too. The challenges faced by VNPs in biomedical applications are identified, and solutions are provided to overcome them.

EXPERT OPINION

In the development of next-generation VNPs for gene therapy, bioimaging and therapeutic deliveries, focus must be given to reduce their immunogenicity, and increase their stability in the circulatory system. Modular virus-like particles (VLPs) which are produced separately from their cargoes or ligands before all the components are coupled can speed up clinical trials and commercialization. In addition, removal of contaminants from VNPs, cargo delivery across the blood brain barrier (BBB), and targeting of VNPs to organelles intracellularly are challenges that will preoccupy researchers in this decade.

Development of a MET-targeted single-chain antibody fragment as an anti-oncogene targeted therapy for breast cancer

The usage of monoclonal antibodies (mAbs) and antibody fragments, as a matter associated with the biopharmaceutical industry, is increasingly growing. Harmonious with this concept, we designed an exclusive modeled single-chain variable fragment (scFv) against mesenchymal-epithelial transition (MET) oncoprotein. This scFv was newly developed from Onartuzumab sequence by gene cloning, and expression using bacterial host. Herein, we examined its preclinical efficacy for the reduction of tumor growth, invasiveness and angiogenesis in vitro and in vivo. Expressed anti-MET scFv demonstrated high binding capacity (48.8%) toward MET-overexpressing cancer cells. The IC₅₀ value of anti-MET scFv against MET-positive human breast cancer cell line (MDA-MB-435) was 8.4 µg/ml whereas this value was measured as 47.8 µg/ml in MET-negative cell line BT-483. Similar concentrations could also effectively induce apoptosis in MDA-MB-435 cancer cells. Moreover, this antibody fragment could reduce migration and invasion in MDA-MB-435 cells. Grafted breast tumors in Balb/c mice showed significant tumor growth suppression as well as reduction of blood-supply in response to recombinant anti-MET treatment. Histopathology and immunohistochemical assessments revealed higher rate of response to therapy. In our study, we designed and synthetized a novel anti-MET scFv which could effectively suppress MET-overexpressing breast cancer tumors.

Antibody-Incorporated Nanomedicines for Cancer Therapy

Antibody-based cancer therapy, one of the most significant therapeutic strategies, has achieved considerable success and progress over the past decades. Nevertheless, obstacles including limited tumor penetration, short circulation half-lives, undesired immunogenicity, and off-target side effects remain to be overcome for the antibody-based cancer treatment. Owing to the rapid development of nanotechnology, antibody-containing nanomedicines that have been extensively explored to overcome these obstacles have already demonstrated enhanced anticancer efficacy and clinical translation potential. This review intends to offer an overview of the advancements of antibody-incorporated nanoparticulate systems in cancer treatment, together with the nontrivial challenges faced by these next-generation nanomedicines. Diverse strategies of antibody immobilization, formats of antibodies, types of cancer-associated antigens, and anticancer mechanisms of antibody-containing nanomedicines are provided and discussed in this review, with an emphasis on the latest applications. The current limitations and future research directions on antibody-containing nanomedicines are also discussed from different perspectives to provide new insights into the construction of anticancer nanomedicines.

Recent progress in the imaging of c-Met aberrant cancers with positron emission tomography

Tyrosine-protein kinase Met-also known as c-Met or HGFR-is a membrane receptor protein with associated tyrosine kinase activity physiologically stimulated by its natural ligand, the hepatocyte growth factor (HGF), and is involved in different ways in cancer progression and tumourigenesis. Targeting c-Met with pharmaceuticals has been preclinically proved to have significant benefits for cancer treatment. Recently, evaluating the protein status during and before c-Met targeted therapy has been shown of relevant importance by different studies, demonstrating that there is a correlation between the status (e.g., aberrant activation and overexpression) of the HGFR with therapy response and clinical prognosis. Currently, clinical imaging based on positron emission tomography (PET) appears as one of the most promising tools for the in vivo real-time scanning of irregular alterations of the tyrosine-protein kinase Met and for the diagnosis of c-Met related cancers. In this study, we review the recent progress in the imaging of c-Met aberrant cancers with PET. Particular attention is directed on the development of PET probes with a range of different sizes (HGF, antibodies, anticalines, peptides, and small molecules), and radiolabeled with different radionuclides. The goal of this review is to report all the preclinical imaging studies based on PET imaging reported until now for in vivo diagnosis of c-Met in oncology to support the design of novel and more effective PET probes for in vivo evaluation of c-Met.

Multicompartment systems: A putative carrier for combined drug delivery and targeting

In this review, we discuss recent developments in multicompartment systems commonly referred to as vesosomes, as well as their method of preparation, surface modifications, and clinical potential. Vesosomal systems are able to entrap more than one drug moiety and can be customized for site-specific delivery. We focus in particular on the possible reticuloendothelial system (RES) - mediated accumulation of vesosomes, and their application in tumor targeting, as areas for further investigation.

Bio-Nanocarriers for Lung Cancer Management: Befriending the Barriers

Lung cancer is a complex thoracic malignancy developing consequential to aberrations in a myriad of molecular and biomolecular signaling pathways. It is one of the most lethal forms of cancers accounting to almost 1.8 million new annual incidences, bearing overall mortality to incidence ratio of 0.87. The dismal prognostic scenario at advanced stages of the disease and metastatic/resistant tumor cell populations stresses the requisite of advanced translational interdisciplinary interventions such as bionanotechnology. This review article deliberates insights and apprehensions on the recent prologue of nanobioengineering and bionanotechnology as an approach for the clinical management of lung cancer. The role of nanobioengineered (bio-nano) tools like bio-nanocarriers and nanobiodevices in secondary prophylaxis, diagnosis, therapeutics, and theranostics for lung cancer management has been discussed. Bioengineered, bioinspired, and biomimetic bio-nanotools of considerate translational value have been reviewed. Perspectives on existent oncostrategies, their critical comparison with bio-nanocarriers, and issues hampering their clinical bench side to bed transformation have also been summarized.

The impact of molecular tumor profiling on the design strategies for targeting myeloid leukemia and EGFR/CD44-positive solid tumors

Nanomedicine has emerged as a novel cancer treatment and diagnostic modality, whose design constantly evolves towards increasing the safety and efficacy of the chemotherapeutic and diagnostic protocols. Molecular diagnostics, which create a great amount of data related to the unique molecular signatures of each tumor subtype, have emerged as an important tool for detailed profiling of tumors. They provide an opportunity to develop targeting agents for early detection and diagnosis, and to select the most effective combinatorial treatment options. Alongside, the design of the nanoscale carriers needs to cope with novel trends of molecular screening. Also, multiple targeting ligands needed for robust and specific interactions with the targeted cell populations have to be introduced, which should result in substantial improvements in safety and efficacy of the cancer treatment. This article will focus on novel design strategies for nanoscale drug delivery systems, based on the unique molecular signatures of myeloid leukemia and EGFR/CD44-positive solid tumors, and the impact of novel discoveries in molecular tumor profiles on future chemotherapeutic protocols.

Enhancement of tumor tropism of mPEGylated nanoparticles by anti-mPEG bispecific antibody for ovarian cancer therapy

Ovarian cancer is highly metastatic, with a high frequency of relapse, and is the most fatal gynecologic malignancy in women worldwide. It is important to elevate the drug susceptibility and cytotoxicity of ovarian cancer cells, thereby eliminating resident cancer cells for more effective therapeutic efficacy. Here, we developed a bispecific antibody (BsAb; mPEG × HER2) that can easily provide HER2⁺ tumor tropism to mPEGylated liposomal doxorubicin (PLD) and further increase the drug accumulation in cancer cells via receptor-mediated endocytosis, and improve the cytotoxicity and therapeutic efficacy of HER2⁺ ovarian tumors. The mPEG × HER2 can simultaneously bind to mPEG molecules on the surface of PLD and HER2 antigen on the surface of ovarian cancer cells. Simply mixing the mPEG × HER2 with PLD was able to confer HER2 specificity of PLD to HER2⁺ ovarian cancer cells and efficiently trigger endocytosis and enhance cytotoxicity by 5.4-fold as compared to non-targeted PLD. mPEG × HER2-modified PLD was able to significantly increase the targeting and accumulation of HER2⁺ ovarian tumor by 220% as compared with non-targeted PLD. It could also significantly improve the anti-tumor activity of PLD (P < 0.05) with minimal obvious toxicity in a tumor-bearing mouse model. We believe that the mPEG × HER2 can significantly improve the therapeutic efficacy, potentially reduce the relapse freqency and thereby achieve good prognosis in ovarian cancer patients.

In Vitro and In Vivo Evaluation of Novel DTX-Loaded Multifunctional Heparin-Based Polymeric Micelles Targeting Folate Receptors and Endosomes

BACKGROUND

The development of biocompatible tumor-targeting delivery systems for anticancer agents is essential for efficacious cancer chemotherapy. Nanoparticles, as drug delivery cargoes for cancer therapy, are rapidly improving to overcome the limitations of conventional chemotherapeutic agents. Heparin-modified nanoparticles are currently being considered as one of the favorable carriers for the delivery of chemotherapeutics to cancer tissues.

OBJECTIVE

This study was aimed at evaluating the in vitro and in vivo antitumor activity of a novel targeted, pH-sensitive, heparin-based polymeric micelle loaded with the poorly water-soluble anticancer drug, docetaxel (DTX). The micelles could overcome the limited water solubility, non-specific distribution, and insufficient drug concentration in tumor tissues.

METHODS

DTX-loaded folate targeted micelles were prepared and evaluated for physicochemical properties, drug release, in vitro cellular uptake and cytotoxicity in folate receptor-positive and folate receptor-negative cells. Furthermore, the antitumor activity of DTX-loaded micelles was evaluated in the tumor-bearing mice. Some related patents were also studied in this research.

RESULTS

The heparin-based targeted micelles exhibited higher in vitro cellular uptake and cytotoxicity against folate receptor over-expressed cells due to the specific receptor-mediated endocytosis. DTX-loaded micelles displayed greater antitumor activity, higher anti-angiogenesis effects, and lower systemic toxicity compared with free DTX in a tumor-induced mice model as confirmed by tumor growth monitoring, immunohistochemical evaluation, and body weight shift. DTX-loaded targeting micelles demonstrated no considerable toxicity on major organs of tumor-bearing mice compared with free DTX.

CONCLUSION

Our results indicated that DTX-loaded multifunctional heparin-based micelles with desirable antitumor activity and low toxicity possess great potential as a targeted drug delivery system in the treatment of cancer.

Recent progress on developing of plasmon biosensing of tumor biomarkers: Efficient method towards early stage recognition of cancer

Cancer is the second most extended disease with an improved death rate over the past several time. Due to the restrictions of cancer analysis methods, the patient's real survival rate is unknown. Therefore, early stage diagnosis of cancer is crucial for its strong detection. Bio-analysis based on biomarkers may help to overcome the problem Biosensors with high sensitivity and specificity, low-cost, high analysis speed and minimum limit of detection are practical alternatives for laboratory tests. Surface plasmon resonance (SPR) is reaching a maturity level sufficient for their application in detection and determination cancer biomarkers in clinical samples. This review discusses main concepts and performance characteristics of SPR biosensor. Mainly, it focuses on newly emerged enhanced SPR biosensors towards high-throughput and ultrasensitive screening of cancer biomarkers such as PSA, α-fetoprotein, CEA, CA125, CA 15-3, HER2, ctDNA, ALCAM, hCG, VEGF, TNF, Interleukin, IFN-γ, CD24, CD44, Ferritin, COLIV using labeling processes with focusing on the future application in biomedical research and clinical diagnosis. This article reviews current status of the field, showcasing a series of early successes in the application of SPR for clinical bioanalysis of cancer related biomolecules and detailing a series of considerations regarding sensing schemes, exposing issues with analysis in biofluids, while providing an outlook of the challenges currently associated with plasmonic materials, bioreceptor selection, microfluidics, and validation of a clinical bioassay for applying SPR biosensors to clinical samples. Research opportunities are proposed to further advance the field and transition SPR biosensors from research proof-of-concept stage to actual clinical usage.

Kinetic and thermodynamic study of c-Met interaction with single chain fragment variable (scFv) antibodies using phage based surface plasmon resonance

Mesenchymal epithelial transition factor (c-Met) has been recently regarded as an attractive target for the treatment of cancer. Our previous study showed that c-Met-specific single chain fragment variables (scFvs) can be considered as a promising therapy for cancer, however, their molecular interaction with c-Met protein have not been assessed. Accordingly, in the current study we aim to evaluate the kinetic and thermodynamic properties of c-Met interaction with these scFvs as anticancer agents by means of surface plasmon resonance (SPR) technique. Phage-scFvs were immobilized on the 11-mercaptoundecanoic acid gold chips after carboxylic groups activation by N-ethyl-N-(3-diethylaminopropyl) carbodiimide/N-hydroxysuccinimide and, then the c-Met binding to each scFvs (ES1, ES2, and ES3) at different concentrations (ranging from 20 to 665 μM) was explored. Kinetic studies revealed that ES1 has the highest affinity (K_D = 3.36 × 10^-8) toward its target at 25°C. Calculation of thermodynamic parameters also showed positive values for enthalpy and entropy changes, which was representative of hydrophobic forces between c-Met and ES1. Furthermore, the positive value of Gibbs free energy indicated that c-Met binding to ES1 was enthalpy-driven. Taken together, we concluded that produced ES1 can be applied as promising scFv-based therapy for diagnosis or targeting of c-Met in various cancers.

Novel anti-EGFR scFv human antibody-conjugated immunoliposomes enhance chemotherapeutic efficacy in squamous cell carcinoma of head and neck

BACKGROUND AND OBJECTIVES

Squamous cell carcinoma of head and neck (SCCHN) is the fifth most prevalent cancer worldwide. Because the anatomical complexity of this region, complete surgical resection is often not achievable and conventional chemotherapy would aid locoregional control and mitigate distant metastasis. Nonetheless, the nonspecific cytotoxicity and short in vivo half-life of conventional chemotherapeutic drugs limit their effects. Given the high frequency of overexpression of wild type epidermal growth factor receptor (EGFR), we exploit EGFR as a homing beacon for drug delivery system with cytotoxic payloads.

MATERIALS AND METHODS

We generated fully human anti-EGFR single chain variable fragment (scFv)-conjugated immunoliposomes (IL) containing doxorubicin and vinorelbine and tested their anti-neoplastic efficacy in vitro and in vivo.

RESULT

Our IL enhanced endocytosis and significantly reduced the half maximal inhibitory concentrations of the therapeutic payloads when compared to non-targeting liposomal counterparts in various cell lines of SCCHN. Furthermore, median survival time was significantly prolonged in subcutaneous and orthotopic SCCHN xenograft murine models treated with our IL formulations than those treated with non-targeting counterparts (94 days versus 60 days and 72 days versus 56 days, respectively) without evident increased systemic toxicity.

CONCLUSION

The therapeutic index of the chemotherapeutic payloads was augmented by our EFGR-targeting IL formulation and they are warranted for further development and preclinical trial.

Preparation, Characterization, and in vivo Evaluation of NK4-Conjugated Hydroxycamptothecin-Loaded Liposomes

PURPOSE

In this study, NK4-conjugated hydroxycamptothecin liposomes (NK4-HCPT-Lips) were prepared with the aim of improving drug targeting to the liver.

METHODS

NK4-HCPT-Lips were prepared using the thin-film dispersion method. In vitro antitumor activities were evaluated by MTT assay. HCPT levels in plasma and tissues were determined via high-performance liquid chromatography (HPLC) with camptothecin as the internal standard, and the characteristics, pharmacokinetics, and bio-distribution of NK4-HCPT-Lips were evaluated.

RESULTS

The liposomes showed a regular spherical-shaped morphology, and the entrapment efficiency and drug loading capacity reached 82.5 ± 2.4% and 3.01 ± 0.23%, respectively, with a particle size of 155.6 ± 2.6 nm and a zeta potential of -24.8 ± 3.3 mV. Inhibition effect experiments found that NK4-HCPT-Lips had a good inhibition on the HepG2 cells. Pharmacokinetic studies revealed an increase in the area under the curve and mean residence time as well as a decrease in plasma clearance (p < 0.05) of the NK4-HCPT-Lips compared to those of HCPT liposomes and a commercial HCPT injection. Tissue distribution studies showed that NK4-HCPT-Lips were present at high levels in the liver but were cleared from the kidneys.

CONCLUSION

These results demonstrate that NK4-HCPT-Lips possess excellent liver-targeting attributes, which could enhance the therapeutic effects of drug treatments for hepatic 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.

Lipid-based Nanocarriers for siRNA Delivery: Challenges, Strategies and the Lessons Learned from the DODAX: MO Liposomal System

The possibility of using the RNA interference (RNAi) mechanisms in gene therapy was one of the scientific breakthroughs of the last century. Despite the extraordinary therapeutic potential of this approach, the need for an efficient gene carrier is hampering the translation of the RNAi technology to the clinical setting. Although a diversity of nanocarriers has been described, liposomes continue to be one of the most attractive siRNA vehicles due to their relatively low toxicity, facilitated siRNA complexation, high transfection efficiency and enhanced pharmacokinetic properties. This review focuses on RNAi as a therapeutic approach, the challenges to its application, namely the nucleic acids' delivery process, and current strategies to improve therapeutic efficacy. Additionally, lipid-based nanocarriers are described, and lessons learned from the relation between biophysical properties and biological performance of the dioctadecyldimethylammonium:monoolein (DODAX: MO) system are explored. Liposomes show great potential as siRNA delivery systems, being safe nanocarriers to protect nucleic acids in circulation, extend their half-life time, target specific cells and reduce off-target effects. Nevertheless, several issues related to delivery must be overcome before RNAi therapies reach their full potential, namely target-cell specificity and endosomal escape. Understanding the relationship between biophysical properties and biological performance is an essential step in the gene therapy field.

Nanoparticles modified by triple single chain antibodies for MRI examination and targeted therapy in pancreatic cancer

Precise diagnosis and effective treatment are crucial to the prognosis of pancreatic ductal adenocarcinoma (PDAC). Magnetic iron oxide nanoparticles (IONPs) are superior magnetic resonance imaging (MRI) contrast agents, while antibodies are significant immunotherapy reagents. Herein, we firstly generated a novel nanocomposite combining triple single chain antibodies (scAbs) and IONPs for the detection and treatment of PDAC.

METHODS

Triple scAbs (scAbMUC4, scAbCEACAM6, scFvCD44v6, MCC triple scAbs) were conjugated to the surface of polyethylene glycol modified IONPs (IONPs-PEG), forming the IONPs-PEG-MCC triple scAbs nanocomposite. Characterization of the nanocomposite was performed, and its cytotoxicity, specificity, and apoptosis induction were evaluated. In vivo MRI study and anti-pancreatic cancer effect assessment were performed in tumor-bearing nude mice.

RESULTS

The size of the IONPs-PEG-MCC triple scAbs nanocomposite was about 23.6 nm. The nanocomposite was non-toxic to normal pancreatic ductal epithelial cells, and could specifically bind to and be internalized by MUC4/CEACAM6/CD44v6-expressing PDAC cells. With an r2 relaxivity of 104.2 mM^-1 s^-1, the IONPs-PEG-MCC triple scAbs nanocomposite could significantly shorten the MRI T2-weighted signal intensity both in vitro and in vivo. The IONPs-PEG-MCC triple scAbs nanocomposite also showed a favorable anti-pancreatic cancer effect.

CONCLUSION

In the present study, the IONPs-PEG-MCC triple scAbs nanocomposite was firstly confirmed as a bi-functional nanocomposite in both MRI and treatment, providing its critical clinical transformation potential in PDAC detection and treatment.

Functionalizing nanoparticles with cancer-targeting antibodies: A comparison of strategies

Standard cancer therapies sometimes fail to deliver chemotherapeutic drugs to tumor cells in a safe and effective manner. Nanotechnology takes the lead in providing new therapeutic options for cancer due to major potential for selective targeting and controlled drug release. Antibodies and antibody fragments are attracting much attention as a source of targeting ligands to bind specific receptors that are overexpressed on cancer cells. Therefore, researchers are devoting time and effort to develop targeting strategies based on nanoparticles functionalized with antibodies, which hold great promise to enhance therapeutic efficacy and circumvent severe side effects. Several methods have been described to immobilize antibodies on the surface of nanoparticles. However, selecting the most appropriate for each application is challenging but also imperative to preserve antigen binding ability and yield stable antibody-conjugated nanoparticles. From this perspective, we aim to provide considerable knowledge on the most widely used methods of functionalization that can be helpful for decision-making and design of conjugation protocols as well. This review summarizes adsorption, covalent conjugation (carbodiimide, maleimide and "click" chemistries) and biotin-avidin interaction, while discussing the advantages, limitations and relevant therapeutic approaches currently under investigation.

Chemically Crosslinked Bispecific Antibodies for Cancer Therapy: Breaking from the Structural Restrictions of the Genetic Fusion Approach

Antibodies are composed of structurally and functionally independent domains that can be used as building blocks to construct different types of chimeric protein-format molecules. However, the generally used genetic fusion and chemical approaches restrict the types of structures that can be formed and do not give an ideal degree of homogeneity. In this study, we combined mutation techniques with chemical conjugation to construct a variety of homogeneous bivalent and bispecific antibodies. First, building modules without lysine residues—which can be chemical conjugation sites—were generated by means of genetic mutation. Specific mutated residues in the lysine-free modules were then re-mutated to lysine residues. Chemical conjugation at the recovered lysine sites enabled the construction of homogeneous bivalent and bispecific antibodies from block modules that could not have been so arranged by genetic fusion approaches. Molecular evolution and bioinformatics techniques assisted in finding viable alternatives to the lysine residues that did not deactivate the block modules. Multiple candidates for re-mutation positions offer a wide variety of possible steric arrangements of block modules, and appropriate linkages between block modules can generate highly bioactive bispecific antibodies. Here, we propose the effectiveness of the lysine-free block module design for site-specific chemical conjugation to form a variety of types of homogeneous chimeric protein-format molecule with a finely tuned structure and function.

Development of therapeutic antibodies for the treatment of diseases

It has been more than three decades since the first monoclonal antibody was approved by the United States Food and Drug Administration (US FDA) in 1986, and during this time, antibody engineering has dramatically evolved. Current antibody drugs have increasingly fewer adverse effects due to their high specificity. As a result, therapeutic antibodies have become the predominant class of new drugs developed in recent years. Over the past five years, antibodies have become the best-selling drugs in the pharmaceutical market, and in 2018, eight of the top ten bestselling drugs worldwide were biologics. The global therapeutic monoclonal antibody market was valued at approximately US$115.2 billion in 2018 and is expected to generate revenue of $150 billion by the end of 2019 and $300 billion by 2025. Thus, the market for therapeutic antibody drugs has experienced explosive growth as new drugs have been approved for treating various human diseases, including many cancers, autoimmune, metabolic and infectious diseases. As of December 2019, 79 therapeutic mAbs have been approved by the US FDA, but there is still significant growth potential. This review summarizes the latest market trends and outlines the preeminent antibody engineering technologies used in the development of therapeutic antibody drugs, such as humanization of monoclonal antibodies, phage display, the human antibody mouse, single B cell antibody technology, and affinity maturation. Finally, future applications and perspectives are also discussed.

Preparation of a Novel One-Armed Anti-c-Met Antibody with Antitumor Activity Against Hepatocellular Carcinoma

Introduction

Antibody-based c-mesenchymal–epithelial transition factor (c-Met) inhibition is a promising strategy for hepatocellular carcinoma (HCC) treatment, but the intrinsic agonistic activity of the anti-c-Met antibody limits its application in drug development. Constructing a monovalent one-armed antibody has been reported to be an effective way to create an inhibitory anti-c-Met antibody.

Materials and methods

In the present study, a novel monovalent one-armed anti-c-Met antibody was constructed using the knobs-into-holes technology, and its inhibitory effects against HCC and the underlying mechanisms were explored.

Results

The one-armed anti-c-Met antibody blocked the hepatocyte growth factor (HGF)/c-Met interaction and the subsequent signal transduction, including phosphorylation of c-Met, Grb2-associated binding protein 1(Gab-1), extracellular regulated protein kinases 1/2(Erk1/2), and Akt, also referred to as protein kinase B (PKB) in HCC cell line HepG2. Furthermore, the autocrine stimulation of HepG2 cell proliferation and HGF-induced HCC cell migration were strongly inhibited by the one-armed anti-c-Met antibody. In addition, the antibody also reduced the HGF-induced proliferation and tube formation of human umbilical vein endothelial cells (HUVECs). Treating HepG2-bearing mice with the one-armed anti-c-Met antibody significantly inhibited the tumor growth in the xenograft nude mouse model.

Conclusion

The one-armed anti-c-Met antibody derived from the full-length bivalent anti-c-Met antibody might serve as a potential antitumor agent against HCC.

Specific, Non-Invasive, and Magnetically Directed Targeting of Magnetic Erythrocytes in Blood Vessels of Mice

OBJECTIVE

Targeting in vivo has been a spotlight for precise medicine. Multiple strategies have been proposed for this issue. However, the efficiency of solely biochemical strategies currently remains to be improved. It has been thought that external field-guided targeting will be a beneficial supplement for the passive and the active targeting.

METHODS

Here, we focused on the magnetic field-guided targeting of magnetized erythrocytes, discovering that a focused magnetic field can direct aggregation of magnetic erythrocytes into a specific region in vivo.

RESULTS

The systematic investigation about the aggregates in cerebral vessels showed that the aggregates were isotropic and able to stably exist for six hours. The formation of cellular aggregates can alter echoing characteristic of the blood vessels meaning the vascular wall became more rigid. If the erythrocytes were repeatedly directed into aggregation in an identical region, a stable plaque of erythrocytes can form, which can mimic the process of thrombosis.

SIGNIFICANCE

We believe these results will be beneficial to the development of novel engineered strategy for targeted delivery of drugs and modeling of vascular diseases.

The Intracellular Delivery Of Anti-HPV16 E7 scFvs Through Engineered Extracellular Vesicles Inhibits The Proliferation Of HPV-Infected Cells

Purpose

Single-chain variable fragments (scFvs) are one of the smallest antigen-binding units having the invaluable advantage to be expressed by a unique short open reading frame (ORF). Despite their reduced size, spontaneous cell entry of scFvs remains inefficient, hence precluding the possibility to target intracellular antigens. Here, we describe an original strategy to deliver scFvs inside target cells through engineered extracellular vesicles (EVs). This approach relies on the properties of a Human Immunodeficiency Virus (HIV)-1 Nef mutant protein referred to as Nef^mut. It is a previously characterized Nef allele lacking basically all functions of wt Nef, yet strongly accumulating in the EV lumen also when fused at its C-terminus with a foreign protein. To gain the proof-of-principle for the efficacy of the proposed strategy, the tumor-promoting Human Papilloma Virus (HPV)16-E7 protein was considered as a scFv-specific intracellular target. The oncogenic effect of HPV16-E7 relies on its binding to the tumor suppressor pRb protein leading to a dysregulated cell duplication. Interfering with this interaction means impairing the HPV16-E7-induced cell proliferation.

Methods

The Nef^mut gene was fused in frame at its 3ʹ-terminus with the ORF coding for a previously characterized anti-HPV16-E7 scFv. Interaction between the Nef^mut-fused anti-HPV16-E7 scFv and the HPV16-E7 protein was tested by both confocal microscope and co-immunoprecipitation analyses on co-transfected cells. The in cis anti-proliferative effect of the Nef^mut/anti-HPV16-E7 scFv was assayed by transfecting HPV16-infected cells. The anti-proliferative effect of EVs engineered with Nef^mut/anti-HPV16-E7 scFv on HPV16-E7-expressing cells was evaluated in two ways: i) through challenge with purified EVs by a Real-Time Cell Analysis system and ii) in transwell co-cultures by an MTS-based assay.

Results

The Nef^mut/anti-HPV16-E7 scFv chimeric product is efficiently uploaded in EVs, binds HPV16-E7, and inhibits the proliferation of HPV16-E7-expressing cells. Most important, challenge with cell-free EVs incorporating the Nef^mut/anti-HPV16-E7 scFv led to the inhibition of proliferation of HPV16-E7-expressing cells. The proliferation of these cells was hindered also when they were co-cultured in transwells with cells producing EVs uploading Nef^mut/anti-HPV16-E7 scFv.

Conclusion

Our data represent the proof-of-concept for the possibility to target intracellular antigens through EV-mediated delivery of scFvs. This finding could be relevant to design novel methods of intracellular therapeutic interventions.

Novel human Ab against vascular endothelial growth factor receptor 2 shows therapeutic potential for leukemia and prostate cancer

Vascular endothelial growth factor receptor 2 (VEGFR2) is highly expressed in tumor‐associated endothelial cells, where it modulates tumor‐promoting angiogenesis, and it is also found on the surface of tumor cells. Currently, there are no Ab therapeutics targeting VEGFR2 approved for the treatment of prostate cancer or leukemia. Therefore, development of novel efficacious anti‐VEGFR2 Abs will benefit cancer patients. We used the Institute of Cellular and Organismic Biology human Ab library and affinity maturation to develop a fully human Ab, anti‐VEGFR2‐AF, which shows excellent VEGFR2 binding activity. Anti‐VEGFR2‐AF bound Ig‐like domain 3 of VEGFR2 extracellular region to disrupt the interaction between VEGF‐A and VEGFR2, neutralizing downstream signaling of the receptor. Moreover, anti‐VEGFR2‐AF inhibited capillary structure formation and exerted Ab‐dependent cell‐mediated cytotoxicity and complement‐dependent cytotoxicity in vitro. We found that VEGFR2 is expressed in PC‐3 human prostate cancer cell line and associated with malignancy and metastasis of human prostate cancer. In a PC‐3 xenograft mouse model, treatment with anti‐VEGFR2‐AF repressed tumor growth and angiogenesis as effectively and safely as US FDA‐approved anti‐VEGFR2 therapeutic, ramucirumab. We also report for the first time that addition of anti‐VEGFR2 Ab can enhance the efficacy of docetaxel in the treatment of a prostate cancer mouse model. In HL‐60 human leukemia‐xenografted mice, anti‐VEGFR2‐AF showed better efficacy than ramucirumab with prolonged survival and reduced metastasis of leukemia cells to ovaries and lymph nodes. Our findings suggest that anti‐VEGFR2‐AF has strong potential as a cancer therapy that could directly target VEGFR2‐expressing tumor cells in addition to its anti‐angiogenic action.

Impacts of the -1 Amino Acid on Yeast Production of Protein-Intein Fusions

Expressing antibodies as fusions to the non-self-cleaving Mxe GyrA intein allows for site-specific chemical functionalization via expressed protein ligation. It is highly desirable to maximize the yield of functionalizable protein; and previously an evolved intein, 202-08, was identified that could increase protein fusion production in yeast. Given that the -1 amino acid residue upstream of inteins can affect cleavage efficiency, we examined the effects of amino acid variability at this position on 202-08 intein cleavage efficiency and secretion yield. Varying the -1 residue resulted in a wide range of cleavage behaviors with some amino acids yielding substantial autocleaved product that could not be functionalized. Autocleavage was noticeably higher with the 202-08 intein compared with the wild-type Mxe GyrA intein and resulted directly from the catalytic activity of the intein. Refeeding of production cultures with nitrogen base and casamino acids reduced, but did not eliminate autocleavage, while increasing protein-intein production up to seven-fold. Importantly, two amino acids, Gly and Ala, at the -1 position resulted in good cleavage efficiency with no undesirable autocleavage, and can be used in concert with refeeding strategies to increase total functionalizable protein yield for multiple protein fusion partners. Taken together, we describe an optimized yeast expression platform for protein-intein fusions. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2736, 2019.

A novel anti-PSMA human scFv has the potential to be used as a diagnostic tool in prostate cancer

Prostate cancer (PCa) is the most commonly diagnosed malignancy and the second leading cause of cancer related death in men. The early diagnosis and treatment of PCa are still challenging due to the lack of efficient tumor targeting agents in traditional managements. Prostate specific membrane antigen (PSMA) is highly expressed in PCa, while only has limited expression in other organs, providing an ideal target for the diagnosis and therapy of PCa. The antibody library technique has opened the avenue for the discovery of novel antibodies to be used in the diagnosis and therapy of cancer. In this paper, by screening a large yeast display naive human single chain antibody fragment (scFv) library, we obtained a high affinity scFv targeting PSMA, called gy1. The gy1 scFv was expressed in E.coli and purified via a C terminal 6His tag. The binding affinity of gy1 was shown to be at the nanomolar level and gy1 can specifically bind with PSMA positive cancer cells, and binding triggers its rapid internalization through the endosome-lysosome pathway. The specific targeting of gy1 to PSMA positive tumor tissues was also evaluated in vivo. We showed that the IRDye800CW labeled gy1 can efficiently target and specifically distribute in PSMA positive tumor tissues after being injected into xenograft nude mice. This study indicated that the novel antibody gy1 could be used as a great tool for the development of PSMA targeted imaging and therapy agents for PCa.

Recent Advances in the Generation of Antibody-Nanomaterial Conjugates

Targeted nanomedicines have significantly changed the way new therapeutics are designed to treat disease. Central to successful therapeutics is the ability to control the dynamics of protein-nanomaterial interactions to enhance the therapeutic effect of the nanomedicine. The aim of this review is to illustrate the diversity and versatility of the conjugation approaches involved in the synthesis of antibody-nanoparticle conjugates, and highlight significant new advances in the field of bioconjugation. Such nanomedicines have found utility as both advanced therapeutic agents, as well as more complex imaging contrast agents that can provide both anatomical and functional information of diseased tissue. While such conjugates show significant promise as next generation targeted nanomedicines, it is recognized that there are in fact no clinically approved targeted therapeutics on the market. This fact is reflected upon within this review, and attempts are made to draw some reasoning from the complexities associated with the bioconjugation chemistry approaches that are typically utilized. Present trends, as well as future directions of next generation targeted nanomedicines are also discussed.

Hepatocellular carcinoma-targeted nanoparticles for cancer therapy

Nanocarriers, such as liposomes, have the potential to increase the payload of chemotherapeutic drugs while decreasing toxicity to non-target tissues; such advantageous properties can be further enhanced through surface conjugation of nanocarriers with targeting moieties. We previously reported that SP94 peptides, identified by phage display, exhibited higher binding affinity to human hepatocellular carcinoma (HCC) than to hepatocytes and other normal cells. Here, we confirm the tumor-targeting properties of SP94 peptide by near-infrared fluorescence imaging. Non-targeted PEGylated liposomal doxorubicin (LD) and SP94‑conjugated PEGylated liposomal doxorubicin (SP94‑LD) were compared by assessing pharmacokinetics, tissue distribution, and antitumor efficacy in xenograft-bearing mice, in order to investigate the effectiveness of SP94‑mediated targeting for cancer therapy. SP94‑LD demonstrated a significant increase in drug accumulation in tumors, while its plasma residence time was the same as its non-targeted equivalent. Consistent with this result, conjugation of targeting peptide SP94 enhances the therapeutic efficacy of liposomal doxorubicin in mouse models with hepatocellular carcinoma xenografts. Furthermore, combination targeted therapy exhibited a significant enhancement against orthotopic tumor growth, and markedly extended the survival of mice compared with all other treatments. Our study shows that SP94‑mediated targeting enhances antitumor efficacy by improving tumor pharmacokinetics and tissue distribution, allowing large amounts of antitumor drugs to accumulate in tumors.

Therapeutic targeting in nanomedicine: the future lies in recombinant antibodies

The unique chemical and functional properties of nanoparticles can be harnessed for the delivery of large quantities of various therapeutic biomolecules. Active targeting of nanoparticles by conjugating ligands that bind to target cells strongly facilitates accumulation, internalization into target cells and longer retention at the target site, with consequent enhanced therapeutic effects. Recombinant antibodies with high selectivity and availability for a vast range of targets will dominate the future. In this review, we systematically outline the tremendous progress in the conjugation of antibodies to nanoparticles and the clear advantages that recombinant antibodies offer in the therapeutic targeting of nanoparticles. The demonstrated flexibility of recombinant antibody coupling to nanoparticles highlights the bright future of this technology for modern therapeutic nanomedicine.

Antibody-targeted nanoparticles for cancer treatment

Nanoparticles (NPs) are diverse and versatile with physical properties that can be employed for use in cancer medicine. Targeting NPs using antibodies and antibody fragments could overcome some of the limitations seen with current targeted therapies. This review will discuss the role of antibody-targeted NPs in the treatment of cancer: as delivery vehicles, targeted theranostic agents and in the evolving field of cancer hyperthermia.

Analysis of progress and challenges for various patterns of c-MET-targeted molecular imaging: a systematic review

Background

Mesenchymal–epithelial transition factor also named c-MET is a receptor tyrosine kinase for the hepatocyte growth factor that plays a pivotal role in tumorigenesis. c-MET-targeted therapies have been tested in preclinical models and patients, with significant benefits for cancer treatment. In recent years, many studies have shown that the expression level and activation status of c-MET are closely correlated to c-MET-targeted therapy response and clinical prognosis, thus highlighting the importance of evaluating the c-MET status during and prior to targeted therapy. Molecular imaging allows the monitoring of abnormal alterations of c-MET in real time and in vivo.

Results

In this review, we initially summarize the recent advances in c-MET-targeted molecular imaging, with a special focus on the development of imaging agents ranging in size from monoclonal antibody to small molecule. The aim of this review is to report the preclinical results and clinical application of all molecular imaging studies completed until now for in vivo detection of c-MET in cancer, in order to be beneficial to development of molecular probe and the combination of molecular imaging technologies for in vivo evaluation of c-MET. Various molecular probe targeted to c-MET possesses distinctive advantages and disadvantages. For example, antibody-based probes have high binding affinity but with long metabolic cycle as well as remarkable immunogenicity.

Conclusions

Although studies for c-MET-targeted molecular imaging have made many important advances, most of imaging agents specifically target to extracellular area of c-MET receptor; however, it is difficult to reflect entirely activation of c-MET. Therefore, small molecule probes based on tyrosine kinase inhibitors, which could target to intracellular area of c-MET without any immunogenicity, should be paid more attention.

Lung Cancer-Targeting Peptides with Multi-subtype Indication for Combinational Drug Delivery and Molecular Imaging

Lung cancer is the leading cause of cancer-related death worldwide. Most targeted drugs approved for lung cancer treatment are tyrosine kinase inhibitors (TKIs) directed against EGFR or ALK, and are used mainly for adenocarcinoma. At present, there is no effective or tailored targeting agent for large cell carcinoma (LCC) or small cell lung cancer (SCLC). Therefore, we aimed to identify targeting peptides with diagnostic and therapeutic utility that possess broad subtype specificity for SCLC and non-small cell lung cancer (NSCLC). We performed phage display biopanning of H460 LCC cells to select broad-spectrum lung cancer-binding peptides, since LCC has recently been categorized as an undifferentiated tumor type within other histological subcategories of lung cancer. Three targeting phages (HPC1, HPC2, and HPC4) and their respective displayed peptides (HSP1, HSP2, and HSP4) were able to bind to both SCLC and NSCLC cell lines, as well as clinical specimens, but not to normal pneumonic tissues. In vivo optical imaging of phage homing and magnetic resonance imaging (MRI) of peptide-SPIONs revealed that HSP1 was the most favorable probe for multimodal molecular imaging. Using HSP1-SPION, the T2-weighted MR signal of H460 xenografts was decreased up to 42%. In contrast to the tight binding of HSP1 to cancer cell surfaces, HSP4 was preferentially endocytosed and intracellular drug delivery was thereby effected, significantly improving the therapeutic index of liposomal drug in vivo. Liposomal doxorubicin (LD) conjugated to HSP1, HSP2, or HSP4 had significantly greater therapeutic efficacy than non-targeting liposomal drugs in NSCLC (H460 and H1993) animal models. Combined therapy with an HSP4-conjugated stable formulation of liposomal vinorelbine (sLV) further improved median overall survival (131 vs. 84 days; P = 0.0248), even in aggressive A549 orthotopic models. Overall, these peptides have the potential to guide a wide variety of tailored theranostic agents for targeting therapeutics, non-invasive imaging, or clinical detection of SCLC and NSCLC.

Anti-HER2 VHH Targeted Magnetoliposome for Intelligent Magnetic Resonance Imaging of Breast Cancer Cells

The combination of liposomes with magnetic nanoparticles, because of their strong effect on T2 relaxation can open new ways in the innovative cancer therapy and diagnosis. In order to design an intelligent contrast agent in MRI, we chose anti-HER2 nanobody the smallest fully functional antigen-binding fragments evolved from the variable domain, the VHH, of a camel heavy chain-only antibody. These targeted magnetoliposomes bind to the HER2 antigen which is highly expressed on breast and ovarian cancer cells so reducing the side effects as well as increasing image contrast and effectiveness. Cellular iron uptake analysis and in vitro MRI of HER2 positive cells incubated with targeted nanoparticles show specific cell targeting. In vitro MRI shows even at the lowest density (200 Cells/μl), dark spots corresponding to labeled cells which were still detectable. These results suggest that this new type of nanoparticles could be effective antigen-targeted contrast agents for molecular imaging.

Enzyme-Sensitive and Amphiphilic PEGylated Dendrimer-Paclitaxel Prodrug-Based Nanoparticles for Enhanced Stability and Anticancer Efficacy

In this study, we prepared a smart polymeric vehicle for the hydrophobic drug paclitaxel (PTX) that allowed a maximum steady-state circulation and a fast intracellular release in tumors. PTX was linked to the Janus PEGylated (PEG = poly(ethylene glycol)) peptide dendrimer via an enzyme-sensitive linker glycylphenylalanylleucylglycine tetrapeptide by efficient click reaction, resulting in Janus dendritic prodrug with 20.9% PTX content. The prodrug self-assembled into nanoscale particles with appropriate nanosizes, compact morphology, and negative surface charge. In addition to high stability during circulation, as demonstrated by protein adsorption assays and drug release studies in the cancer's intracellular environment, the nanoparticles were able to quickly release the drug intact in its original molecular structure, as verified via high-performance liquid chromatography and mass spectrometry analyses. Compared to free PTX, the enzyme-responsive feature of nanoparticles promoted higher cytotoxicity against 4T1 cancer cells and much lower cytotoxicity against normal cells. The nanoparticles accumulated in the tumor and were retained for an extended period of time, as confirmed by fluorescence imaging. Therefore, these nanoparticles exhibited significantly enhanced antitumor efficiency in the 4T1 breast cancer model as indicated by the observed inhibition of angiogenesis and proliferation as well as induction of apoptosis. Moreover, the nanoparticles reduced the occurrence of side effects, particularly dose-limited toxicities, as monitored by body weight and hematological features. Hence, our Janus PEGylated dendrimer-PTX prodrug-based nanoparticles may potentially serve as nanoscale vehicles for breast cancer therapy.

Isolation and characterization of anti c-met single chain fragment variable (scFv) antibodies

The receptor tyrosine kinase (RTK) Met is the cell surface receptor for hepatocyte growth factor (HGF) involved in invasive growth programs during embryogenesis and tumorgenesis. There is compelling evidence suggesting important roles for c-Met in colorectal cancer proliferation, migration, invasion, angiogenesis, and survival. Hence, a molecular inhibitor of an extracellular domain of c-Met receptor that blocks c-Met-cell surface interactions could be of great thera-peutic importance. In an attempt to develop molecular inhibitors of c-Met, single chain variable fragment (scFv) phage display libraries Tomlinson I + J against a specific synthetic oligopeptide from the extracellular domain of c-Met receptor were screened; selected scFv were then characterized using various immune techniques. Three c-Met specific scFv (ES1, ES2, and ES3) were selected following five rounds of panning procedures. The scFv showed specific binding to c-Met receptor, and significantly inhibited proliferation responses of a human colorectal carcinoma cell line (HCT-116). Moreover, anti- apoptotic effects of selected scFv antibodies on the HCT-116 cell line were also evaluated using Annexin V/PI assays. The results demonstrated rates of apoptotic cell death of 46.0, 25.5, and 37.8% among these cells were induced by use of ES1, ES2, and ES3, respectively. The results demonstrated ability to successfully isolate/char-acterize specific c-Met scFv that could ultimately have a great therapeutic potential in immuno-therapies against (colorectal) cancers.

Selecting Targets for Tumor Imaging: An Overview of Cancer-Associated Membrane Proteins

Tumor targeting is a booming business: The global therapeutic monoclonal antibody market accounted for more than $78 billion in 2012 and is expanding exponentially. Tumors can be targeted with an extensive arsenal of monoclonal antibodies, ligand proteins, peptides, RNAs, and small molecules. In addition to therapeutic targeting, some of these compounds can also be applied for tumor visualization before or during surgery, after conjugation with radionuclides and/or near-infrared fluorescent dyes. The majority of these tumor-targeting compounds are directed against cell membrane-bound proteins. Various categories of targetable membrane-bound proteins, such as anchoring proteins, receptors, enzymes, and transporter proteins, exist. The functions and biological characteristics of these proteins determine their location and distribution on the cell membrane, making them more, or less, accessible, and therefore, it is important to understand these features. In this review, we evaluate the characteristics of cancer-associated membrane proteins and discuss their overall usability for cancer targeting, especially focusing on imaging applications.

Oligonucleotide-based theranostic nanoparticles in cancer therapy

Theranostic approaches, combining the functionality of both therapy and imaging, have shown potential in cancer nanomedicine. Oligonucleotides such as small interfering RNA and microRNA, which are powerful therapeutic agents, have been effectively employed in theranostic systems against various cancers. Nanoparticles are used to deliver oligonucleotides into tumors by passive or active targeting while protecting the oligonucleotides from nucleases in the extracellular environment. The use of quantum dots, iron oxide nanoparticles and gold nanoparticles and tagging with contrast agents, like fluorescent dyes, optical or magnetic agents and various radioisotopes, has facilitated early detection of tumors and evaluation of therapeutic efficacy. In this article, we review the advantages of theranostic applications in cancer therapy and imaging, with special attention to oligonucleotide-based therapeutics.