Recent trends in antibody-based oncologic imaging

Approaches to Reducing Normal Tissue Radiation from Radiolabeled Antibodies

Radiolabeled antibodies are powerful tools for both imaging and therapy in the field of nuclear medicine. Radiolabeling methods that do not release radionuclides from parent antibodies are essential for radiolabeling antibodies, and practical radiolabeling protocols that provide high in vivo stability have been established for many radionuclides, with a few exceptions. However, several limitations remain, including undesirable side effects on the biodistribution profiles of antibodies. This review summarizes the numerous efforts made to tackle this problem and the recent advances, mainly in preclinical studies. These include pretargeting approaches, engineered antibody fragments and constructs, the secondary injection of clearing agents, and the insertion of metabolizable linkages. Finally, we discuss the potential of these approaches and their prospects for further clinical application.

Near-infrared fluorescence imaging of hepatocellular carcinoma cells regulated by β-catenin signaling pathway

Background

Near-infrared fluorescence (NIRF) imaging has recently emerged as a promising tool for noninvasive cancer imaging. However, lack of tumor sensitivity and specificity restricts the application of NIRF dyes in surgical navigation.

Methods

Herein, we investigated the imaging features of NIRF dye MHI-148 and indocyanine green (ICG) in live cell imaging and xenograft nude mice models. TCGA dataset analysis and immunohistochemistry were conducted to investigate the expression of OATPs or ABCGs in hepatocellular carcinoma (HCC) tissues. OATPs or ABCGs were knocked down and overexpressed in HCC cells using transient transfection by siRNA and plasmids or stable transfection by lentivirus. Further, qRT-PCR ,Western blotting and the use of agonists or inhibitors targeting β-catenin signaling pathway were applied to explore its important role in regulation of OATP2B1 and ABCG2 expression.

Results

Here we demonstrated that NIRF dye MHI-148 was biocompatible as indocyanine green (ICG) but with higher imaging intensity and preferential uptake and retention in hepatocellular carcinoma (HCC) cells and tissues. Moreover, our data indicated that membrane transporters OATP2B1 and ABCG2, which regulated by β-catenin signaling pathway, mediated tumor-specific accumulation and retention of MHI-148 in HCC cells. In addition, the treatment with β-catenin inhibitor significantly enhanced the accumulation of MHI-148 in HCC tissues and improved the efficacy of tumor imaging with MHI-148 in vivo.

Conclusions

Our study uncovers a mechanism that links the distribution and expression of the membrane transporters OATP2B1 and ABCG2 to the tumor-specific accumulation of MHI-148, and provides evidence supporting a regulating role of the β-catenin signaling pathway in OATP2B1 and ABCG2- induced retention of MHI-148 inHCC tissues, and strategy targeting key components of MHI-148 transport machinery may be a potential approach to improve HCC imaging.

Reduction-Activatable Fluorogenic Nanobody for Targeted and Low-Background Bioimaging

Environment-sensitive fluorogenic antibodies enable target-specific bioimaging with reduced unspecific background signal and improved spatiotemporal resolution. However, current strategies for the construction of fluorogenic antibodies are hard to handle due to challenges that lie in the prior design of fluorogenic probes and subsequent antibody labeling. Here, we report a simple strategy to generate a fluorogenic nanobody, which we term D-body, by in situ incorporation of a reduction-responsive Nile blue foldamer which is self-quenched via a dimerization-caused quenching mechanism. The D-body can be efficiently internalized by cells with high epidermal growth factor receptor expression levels and is highly fluorogenic upon lysosomal activation, allowing wash-free cell imaging with exquisite specificity and fast in vivo imaging with a high tumor-to-background ratio. The modular D-body is readily available and easy to handle, offering a platform that is highly tunable for bioimaging applications.

Conformation specific antagonistic high affinity antibodies to the RON receptor kinase for imaging and therapy

The RON receptor tyrosine kinase is an exceptionally interesting target in oncology and immunology. It is not only overexpressed in a wide variety of tumors but also has been shown to be expressed on myeloid cells associated with tumor infiltration, where it serves to dampen tumour immune responses and reduce the efficacy of anti-CTLA4 therapy. Potent and selective inhibitory antibodies to RON might therefore both inhibit tumor cell growth and stimulate immune rejection of tumors. We derived cloned and sequenced a new panel of exceptionally avid anti-RON antibodies with picomolar binding affinities that inhibit MSP-induced RON signaling and show remarkable potency in antibody dependent cellular cytotoxicity. Antibody specificity was validated by cloning the antibody genes and creating recombinant antibodies and by the use of RON knock out cell lines. When radiolabeled with 89-Zirconium, the new antibodies 3F8 and 10G1 allow effective immuno-positron emission tomography (immunoPET) imaging of RON-expressing tumors and recognize universally exposed RON epitopes at the cell surface. The 10G1 was further developed into a novel bispecific T cell engager with a 15 pM EC50 in cytotoxic T cell killing assays.

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.

The Need to Pair Molecular Monitoring Devices with Molecular Imaging to Personalize Health

By enabling the non-invasive monitoring and quantification of biomolecular processes, molecular imaging has dramatically improved our understanding of disease. In recent years, non-invasive access to the molecular drivers of health versus disease has emboldened the goal of precision health, which draws on concepts borrowed from process monitoring in engineering, wherein hundreds of sensors can be employed to develop a model which can be used to preventatively detect and diagnose problems. In translating this monitoring regime from inanimate machines to human beings, precision health posits that continual and on-the-spot monitoring are the next frontiers in molecular medicine. Early biomarker detection and clinical intervention improves individual outcomes and reduces the societal cost of treating chronic and late-stage diseases. However, in current clinical settings, methods of disease diagnoses and monitoring are typically intermittent, based on imprecise risk factors, or self-administered, making optimization of individual patient outcomes an ongoing challenge. Low-cost molecular monitoring devices capable of on-the-spot biomarker analysis at high frequencies, and even continuously, could alter this paradigm of therapy and disease prevention. When these devices are coupled with molecular imaging, they could work together to enable a complete picture of pathogenesis. To meet this need, an active area of research is the development of sensors capable of point-of-care diagnostic monitoring with an emphasis on clinical utility. However, a myriad of challenges must be met, foremost, an integration of the highly specialized molecular tools developed to understand and monitor the molecular causes of disease with clinically accessible techniques. Functioning on the principle of probe-analyte interactions yielding a transducible signal, probes enabling sensing and imaging significantly overlap in design considerations and targeting moieties, however differing in signal interpretation and readout. Integrating molecular sensors with molecular imaging can provide improved data on the personal biomarkers governing disease progression, furthering our understanding of pathogenesis, and providing a positive feedback loop toward identifying additional biomarkers and therapeutics. Coupling molecular imaging with molecular monitoring devices into the clinical paradigm is a key step toward achieving precision health.

Nanobodies as molecular imaging probes

Camelidae derived single-domain antibodies (sdAbs), commonly known as nanobodies (Nbs), are the smallest antibody fragments with full antigen-binding capacity. Owing to their desirable properties such as small size, high specificity, strong affinity, excellent stability, and modularity, nanobodies are on their way to overtake conventional antibodies in terms of popularity. To date, a broad range of nanobodies have been generated against different molecular targets with applications spanning basic research, diagnostics, and therapeutics. In the field of molecular imaging, nanobody-based probes have emerged as a powerful tool. Radioactive or fluorescently labeled nanobodies are now used to detect and track many targets in different biological systems using imaging techniques. In this review, we provide an overview of the use of nanobodies as molecular probes. Additionally, we discuss current techniques for the generation, conjugation, and intracellular delivery of nanobodies.

Preclinical Molecular PET-CT Imaging Targeting CDCP1 in Colorectal Cancer

Colorectal cancer (CRC) is the third most common malignancy in the world, with 22% of patients presenting with metastatic disease and a further 50% destined to develop metastasis. Molecular imaging uses antigen-specific ligands conjugated to radionuclides to detect and characterise primary cancer and metastases. Expression of the cell surface protein CDCP1 is increased in CRC, and here we sought to assess whether it is a suitable molecular imaging target for the detection of this cancer. CDCP1 expression was assessed in CRC cell lines and a patient-derived xenograft to identify models suitable for evaluation of radio-labelled 10D7, a CDCP1-targeted, high-affinity monoclonal antibody, for preclinical molecular imaging. Positron emission tomography-computed tomography was used to compare zirconium-89 (⁸⁹Zr)-10D7 avidity to a nonspecific, isotype control ⁸⁹Zr-labelled IgGκ1 antibody. The specificity of CDCP1-avidity was further confirmed using CDCP1 silencing and blocking models. Our data indicate high avidity and specificity for of ⁸⁹Zr-10D7 in CDCP1 expressing tumors at. Significantly higher levels than normal organs and blood, with greatest tumor avidity observed at late imaging time points. Furthermore, relatively high avidity is detected in high CDCP1 expressing tumors, with reduced avidity where CDCP1 expression was knocked down or blocked. The study supports CDCP1 as a molecular imaging target for CRC in preclinical PET-CT models using the radioligand ⁸⁹Zr-10D7.

Nanobody-Based Theranostic Agents for HER2-Positive Breast Cancer: Radiolabeling Strategies

The overexpression of human epidermal growth factor 2 (HER2) in breast cancer (BC) has been associated with a more aggressive tumor subtype, poorer prognosis and shorter overall survival. In this context, the development of HER2-targeted radiotracers is crucial to provide a non-invasive assessment of HER2 expression to select patients for HER2-targeted therapies, monitor response and identify those who become resistant. Antibodies represent ideal candidates for this purpose, as they provide high contrast images for diagnosis and low toxicity in the therapeutic setting. Of those, nanobodies (Nb) are of particular interest considering their favorable kinetics, crossing of relevant biological membranes and intratumoral distribution. The purpose of this review is to highlight the unique characteristics and advantages of Nb-based radiotracers in BC imaging and therapy. Additionally, radiolabeling methods for Nb including direct labeling, indirect labeling via prosthetic group and indirect labeling via complexation will be discussed, reporting advantages and drawbacks. Furthermore, the preclinical to clinical translation of radiolabeled Nbs as promising theranostic agents will be reported.

Anti-EGFR Binding Nanobody Delivery System to Improve the Diagnosis and Treatment of Solid Tumours

BACKGROUND

Epidermal Growth Factor Receptor (EGFR) and members of its homologous protein family mediate transmembrane signal transduction by binding to a specific ligand, which leads to regulated cell growth, differentiation, proliferation and metastasis. With the development and application of Genetically Engineered Antibodies (GEAs), Nanobodies (Nbs) constitute a new research hot spot in many diseases. A Nb is characterized by its low molecular weight, deep tissue penetration, good solubility and high antigen-binding affinity, the anti-EGFR Nbs are of significance for the diagnosis and treatment of EGFR-positive tumours.

OBJECTIVE

This review aims to provide a comprehensive overview of the information about the molecular structure of EGFR and its transmembrane signal transduction mechanism, and discuss the anti-EGFR-Nbs influence on the diagnosis and treatment of solid tumours.

METHODS

Data were obtained from PubMed, Embase and Web of Science. All patents are searched from the following websites: the World Intellectual Property Organization (WIPO®), the United States Patent Trademark Office (USPTO®) and Google Patents.

RESULTS

EGFR is a key target for regulating transmembrane signaling. The anti-EGFR-Nbs for targeted drugs could effectively improve the diagnosis and treatment of solid tumours.

CONCLUSION

EGFR plays a role in transmembrane signal transduction. The Nbs, especially anti- EGFR-Nbs, have shown effectiveness in the diagnosis and treatment of solid tumours. How to increase the affinity of Nb and reduce its immunogenicity remain a great challenge.

Antibody-Based Targeted Interventions for the Diagnosis and Treatment of Skin Cancers

BACKGROUND

Cutaneous malignancies most commonly arise from skin epidermal cells. These cancers may rapidly progress from benign to a metastatic phase. Surgical resection represents the gold standard therapeutic treatment of non-metastatic skin cancer while chemo- and/or radiotherapy are often used against metastatic tumors. However, these therapeutic treatments are limited by the development of resistance and toxic side effects, resulting from the passive accumulation of cytotoxic drugs within healthy cells.

OBJECTIVE

This review aims to elucidate how the use of monoclonal Antibodies (mAbs) targeting specific Tumor Associated Antigens (TAAs) is paving the way to improved treatment. These mAbs are used as therapeutic or diagnostic carriers that can specifically deliver cytotoxic molecules, fluorophores or radiolabels to cancer cells that overexpress specific target antigens.

RESULTS

mAbs raised against TAAs are widely in use for e.g. differential diagnosis, prognosis and therapy of skin cancers. Antibody-Drug Conjugates (ADCs) particularly show remarkable potential. The safest ADCs reported to date use non-toxic photo-activatable Photosensitizers (PSs), allowing targeted Photodynamic Therapy (PDT) resulting in targeted delivery of PS into cancer cells and selective killing after light activation without harming the normal cell population. The use of near-infrared-emitting PSs enables both diagnostic and therapeutic applications upon light activation at the specific wavelengths.

CONCLUSION

Antibody-based approaches are presenting an array of opportunities to complement and improve current methods employed for skin cancer diagnosis and treatment.

Nanobodies as in vivo, non-invasive, imaging agents

In vivo imaging has become in recent years an incredible tool to study biological events and has found critical applications in diagnostic medicine. Although a lot of efforts and applications have been achieved using monoclonal antibodies, other types of delivery agents are being developed. Among them, VHHs, antigen binding fragments derived from camelid heavy chain-only antibodies, also known as nanobodies, have particularly attracted attention. Indeed, their stability, fast clearance, good tissue penetration, high solubility, simple cloning and recombinant production make them attractive targeting agents for imaging modalities such as PET, SPECT or Infra-Red. In this review, we discuss the pioneering work that has been carried out using VHHs and summarize the recent developments that have been made using nanobodies for in vivo, non-invasive, imaging.

Optical and magnetic resonance imaging approaches for investigating the tumour microenvironment: state-of-the-art review and future trends

The tumour microenvironment (TME) strongly influences tumorigenesis and metastasis. Two of the most characterized properties of the TME are acidosis and hypoxia, both of which are considered hallmarks of tumours as well as critical factors in response to anticancer treatments. Currently, various imaging approaches exist to measure acidosis and hypoxia in the TME, including magnetic resonance imaging (MRI), positron emission tomography and optical imaging. In this review, we will focus on the latest fluorescent-based methods for optical sensing of cell metabolism and MRI as diagnostic imaging tools applied both in vitro and in vivo. The primary emphasis will be on describing the current and future uses of systems that can measure intra- and extra-cellular pH and oxygen changes at high spatial and temporal resolution. In addition, the suitability of these approaches for mapping tumour heterogeneity, and assessing response or failure to therapeutics will also be covered.

Review: PET imaging with macro- and middle-sized molecular probes

Recent progress in radiolabeling of macro- and middle-sized molecular probes has been extending possibilities to use PET molecular imaging for dynamic application to drug development and therapeutic evaluation. Theranostics concept also accelerated the use of macro- and middle-sized molecular probes for sharpening the contrast of proper target recognition even the cellular types/subtypes and proper selection of the patients who should be treated by the same molecules recognition. Here, brief summary of the present status of immuno-PET, and then further development of advanced technologies related to immuno-PET, peptidic PET probes, and nucleic acids PET probes are described.

Near-infrared fluorescence imaging in immunotherapy

Near-infrared (NIR) light possesses many suitable optophysical properties for medical imaging including low autofluorescence, deep tissue penetration, and minimal light scattering, which together allow for high-resolution imaging of biological tissue. NIR imaging has proven to be a noninvasive and effective real-time imaging methodology that provides a high signal-to-background ratio compared to other potential optical imaging modalities. In response to this, the use of NIR imaging has been extensively explored in the field of immunotherapy. To date, NIR fluorescence imaging has successfully offered reliable monitoring of the localization, dynamics, and function of immune responses, which are vital in assessing not only the efficacy but also the safety of treatments to design immunotherapies optimally. This review aims to provide an overview of the current research on NIR imaging of the immune response. We expect that the use of NIR imaging will expand further in response to the recent success in cancer immunotherapy. We will also offer our insights on how this technology will meet rapidly growing expectations in the future.

Recent advances in nanoscale materials for antibody-based cancer theranostics

The quest for advanced management tools or options of various cancers has been on the rise to efficiently reduce their risks of mortality without the demerits of conventional treatments (e.g., undesirable side effects of the medications on non-target tissues, non-targeted distribution, slow clearance of the administered drugs, and the development of drug resistance over the duration of therapy). In this context, nanomaterials-antibody conjugates can offer numerous advantages in the development of cancer theranostics over conventional delivery systems (e.g., highly specific and enhanced biodistribution of the drug in targeted tissues, prolonged systemic circulation, low toxicity, and minimally invasive molecular imaging). This review comprehensively discusses and evaluates recent advances in the application of nanomaterial-antibody bioconjugates for cancer theranostics for the further advancement in the control of diverse cancerous diseases. Further, discussion is expanded to cover the various challenges and limitations associated with the design and development of nanomaterial-antibody conjugates applicable towards better management of cancer.

Florescence Imaging Lung Cancer with a Small Molecule MHI-148

MHI-148 is a type of heptamethine cyanine dye that can cross the cytoplasmic membrane of lung cancer cells. Here we tested the cytotoxic, in vivo imaging of MHI-148 in lung-cancer nude mice model. Ex vivo imaging was also been measured by testing the major tissue fluorescence intensity. And, the small molecular compound MHI-148 had low cytotoxicity which could be visualized at 1 h post-injection in tumor. From ex vivo fluorescence imaging, the tumor showed the highest uptake of MHI-148 among all the selected organs expect for the time point of 2 h. MHI-148 could be used for effective imaging in lung cancer tissue with good stability and specificity, which suggested that MHI-148 could be an effective tumor clinical imaging agent.

Practical Guide for Quantification of In Vivo Degradation Rates for Therapeutic Proteins with Single-Cell Resolution Using Fluorescence Ratio Imaging

Many tools for studying the pharmacokinetics of biologics lack single-cell resolution to quantify the heterogeneous tissue distribution and subsequent therapeutic degradation in vivo. This protocol describes a dual-labeling technique using two near-infrared dyes with widely differing residualization rates to efficiently quantify in vivo therapeutic protein distribution and degradation rates at the single cell level (number of proteins/cell) via ex vivo flow cytometry and histology. Examples are shown for four biologics with varying rates of receptor internalization and degradation and a secondary dye pair for use in systems with lower receptor expression. Organ biodistribution, tissue-level confocal microscopy, and cellular-level flow cytometry were used to image the multi-scale distribution of these agents in tumor xenograft mouse models. The single-cell measurements reveal highly heterogeneous delivery, and degradation results show the delay between peak tumor uptake and maximum protein degradation. This approach has broad applicability in tracking the tissue and cellular distribution of protein therapeutics for drug development and dose determination.

Optical and Optoacoustic Imaging Probes

Tissue has characteristic properties when it comes to light absorption and scattering. For optical (OI) and optoacoustic imaging (OAI) these properties can be utilised to visualise biological tissue characteristics, as, for example, the oxygenation state of haemoglobin alters the optical and optoacoustic properties of the molecule.

Trivalent metal complex geometry of the substrate governs cathepsin B enzymatic cleavage rate

The identity of the trivalent metal ion controls the rate of the enzymatic cleavage of a series of metal-complexed cathepsin B substrates. Increasing the distance between the metal complex and the enzyme cleavage site diminishes this effect.

Treating tumors with minimally invasive therapy: A review

With high level of morbidity and mortality, tumor is one of the deadliest diseases worldwide. Aiming to tackle tumor, researchers have developed a lot of strategies. Among these strategies, the minimally invasive therapy (MIT) is very promising, for its capability of targeting tumor cells and resulting in a small incision or no incisions. In this review, we will first illustrate some mechanisms and characteristics of tumor metastasis from the primary tumor to the secondary tumor foci. Then, we will briefly introduce the history, characteristics, and advantages of some of the MITs. Finally, emphasis will be, respectively, focused on an overview of the state-of-the-art of the HIFU-, PDT-, PTT-and SDT-based anti-tumor strategies on each stage of tumor metastasis.

P-glycoprotein targeted photodynamic therapy of chemoresistant tumors using recombinant Fab fragment conjugates

P-glycoprotein (Pgp) has been considered as a major cause of cancer multidrug resistance; however, clinical solutions to overcome this drug resistance do not exist despite the tremendous endeavors. The lack of cancer specificity is a main reason for clinical failure of conventional approaches. Targeted photodynamic therapy (PDT) is highly cancer specific by combining antibody targeting and locoregional light irradiation. We aimed to develop Pgp-targeted PDT using antibody-photosensitizer conjugates made of a recombinant Fab fragment. We prepared the photosensitizer conjugates by expressing a recombinant Fab fragment and specifically linking IR700-maleimide at the C-terminal of the Fab heavy chain. In vitro studies showed that the Fab conjugates specifically bind to Pgp. Their phototoxicity was comparable to full antibody conjugates when assayed with conventional 2-D cell culture, but they outperformed the full antibody conjugates in a 3-D tumor spheroid model. In a mouse xenograft model of chemoresistant tumors, Fab conjugates showed Pgp specific delivery to chemoresistant tumors. Upon irradiation with near-infrared light, they caused rapid tumor shrinkage and significantly prolonged the survival of tumor-bearing mice. Compared to the full antibody conjugates, Fab conjugates took a shorter time to reach peak tumor levels and achieved a more homogeneous tumor distribution. This allows light irradiation to be initiated at a shorter time interval after the conjugate injection, and thus may facilitate clinical translation. We conclude that our targeted PDT approach provides a highly cancer-specific approach to combat chemoresistant tumors, and that the conjugates made of recombinant antibody fragments are superior to full antibody conjugates for targeted PDT.

Immunotherapy with oral administration of humanized anti-CD3 monoclonal antibody: a novel gut-immune system-based therapy for metaflammation and NASH

The immune system plays a role in the pathogenesis of non-alcoholic steatohepatitis (NASH) underlying hepatocyte injury and fibrosis progression at all disease stages. Oral administration of anti-CD3 monoclonal antibody (mAb) has been shown in preclinical studies to be an effective method for systemic immune modulation and alleviates immune-mediated disorders without T cell depletion. In the present review, we summarize the concept of the oral administration of humanized anti-CD3 mAb in patients with NASH and discuss the potential of this treatment to address the current requirements of treatments for NASH. Recently published preclinical and clinical data on oral administration of anti CD3 are discussed. Human trials have shown that the oral administration of anti-CD3 in healthy volunteers, patients with chronic hepatitis C virus (HCV) infection and patients with NASH and type 2 diabetes is safe and well tolerated, as well as biologically active. Oral anti-CD3 induces regulatory T cells, suppresses the chronic inflammatory state associated with NASH and exerts a beneficial effect on clinically relevant parameters. Foralumab is a fully human anti-CD3 mAb that has recently been shown to exert a potent anti-inflammatory effect in humanized mice. It is being developed for treatment of NASH and primary biliary cholangitis (PBC). Oral administration of anti CD3 may provide an effective therapy for patients with NASH.

An innovative peptide with high affinity to GPC3 for hepatocellular carcinoma diagnosis

Glypican-3 (GPC3) is a key biomarker for early diagnosis of human hepatocellular carcinoma (HCC) due to its overexpression in most HCC tumor tissues. Recently, peptides with high affinity to GPC3 have attracted more attention because of their high biocompatibility, non-immunogenicity, fast clearing and easy modification. Herein, we have designed an innovative GPC3 targeting peptide (sequence: DYEMHLWWGTEL, denoted as IPA) by using structure-based virtual simulation. The higher binding abilities of IPA over the reported peptide (YP) were displayed on different cell lines, showing a positive correlation with GPC3 expressions, which were further verified by the GPC3 protein binding assay. The GPC3 targeting specificity of IPA was proved by peptide blocking and siRNA experiment. The localized anchor of peptide IPA on the cell membranes of HepG2 and Huh-7 with GPC3 overexpression confirmed the GPC3 binding capacity. By connecting a near-infrared dye MPA, the in vivo identification ability of IPA to GPC3 was also demonstrated on GPC3-positive (HepG2) and GPC3-negative (U87) xenograft-bearing mice. These results indicated that the designed IPA presented desirable GPC3 targeting ability, showing promising prospects in detecting the expression of GPC3 for HCC targeting imaging.

Evaluation of COC183B2 antibody targeting ovarian cancer by near-infrared fluorescence imaging

Objective

To evaluate the imaging potential of a novel near-infrared (NIR) probe conjugated to COC183B2 monoclonal antibodies (MAb) in ovarian cancer (OC).

Methods

The expression of OC183B2 antigen in OC was determined by immunohistochemical (IHC) staining using tissue microarrays with the H-score system and immunofluorescence (IF) staining of tumor cell lines. Imaging probes with the NIR fluorescent dye cyanine 7 (Cy7) conjugated to COC183B2 Mab were chemically engineered. OC183B2-positive human OC cells (SKOV3-Luc) were injected subcutaneously into BALB/c nude mice. Bioluminescent imaging (BLI) was performed to detect tumor location and growth. COC183B2-Cy7 at 1.1, 3.3, 10, or 30 μg were used for in vivo fluorescence imaging, and phosphate-buffered saline (PBS), free Cy7 dye and mouse isotype immunoglobulin G (IgG)-Cy7 (delivered at the same doses as COC183B2-Cy7) were used as controls.

Results

The expression of OC183B2 with a high H-score was more prevalent in OC tissue than fallopian tube (FT) tissue. Among 417 OC patients, the expression of OC183B2 was significantly correlated with the histological subtype, histological grade, residual tumor size, relapse state and survival status. IF staining demonstrated that COC183B2 specifically expressed in SKOV3 cells but not HeLa cells. In vivo NIR fluorescence imaging indicated that COC183B2-Cy7 was mainly distributed in the xenograft and liver with optimal tumor-to-background (T/B) ratios in the xenograft at 30 μg dose. The highest fluorescent signals in the tumor were observed at 96 h post-injection (hpi). Ex vivo fluorescence imaging revealed the fluorescent signals mainly from the tumor and liver. IHC analysis confirmed that xenografts were OC183B2 positive.

Conclusions

COC183B2 is a good candidate for NIR fluorescence imaging and imaging-guided surgery in OC.

Generation and characterization of novel recombinant anti-hERG1 scFv antibodies for cancer molecular imaging

Modern molecular imaging techniques have greatly improved tumor detection and post-treatment follow-up of cancer patients. In this context, antibody-based imaging is rapidly becoming the gold standard, since it combines the unique specificity of antibodies with the sensitivity of the different imaging technologies. The aim of this study was to generate and characterize antibodies in single chain Fragment variable (scFv) format directed to an emerging cancer biomarker, the human ether-à-go-go-related gene-1 (hERG1) potassium channel, and to obtain a proof of concept for their potential use for in vivo molecular imaging.

The anti-hERG1scFv was generated from a full length monoclonal antibody and then mutagenized, substituting a Phenylalanine residue in the third framework of the V_H domain with a Cysteine residue. The resulting scFv-hERG1-Cys showed much higher stability and protein yield, increased affinity and more advantageous binding kinetics, compared to the “native” anti-hERG1scFv. The scFv-hERG1-Cys was hence chosen and characterized: it showed a good binding to the native hERG1 antigen expressed on cells, was stable in serum and displayed a fast pharmacokinetic profile once injected intravenously in nude mice. The calculated half-life was 3.1 hours and no general toxicity or cardiac toxic effects were detected. Finally, the in vivo distribution of an Alexa Fluor 750 conjugated scFv-hERG1-Cys was evaluated both in healthy and tumor-bearing nude mice, showing a good tumor-to-organ ratio, ideal for visualizing hERG1-expressing tumor masses in vivo.

In conclusion, the scFv-hERG1-Cys possesses features which make it a suitable tool for application in cancer molecular imaging.

89 Zr-ImmunoPET companion diagnostics and their impact in clinical drug development

Therapeutic monoclonal antibodies have been used in cancer treatment for 30 years, with around 24 mAb and mAb:drug conjugates approved by the FDA to date. Despite their specificity, efficacy has remained limited, which, in part, derails nascent initiatives towards precision medicine. An image-guided approach to reinforce treatment decisions using immune positron emission tomography (immunoPET) companion diagnostic is warranted. This review provides a general overview of current translational research using Zr-89 immunoPET and opportunities for utilizing and harnessing this tool to its full potential. Patient case studies are cited to illustrate immunoPET probes as tools for profiling molecular signatures. Discussions on its utility in reinforcing clinical decisions as it relates to histopathological tumor assessment and standard diagnostic methods, and its potential as predictive biomarkers, are presented. We finally conclude with an overview of practical considerations to its utility in the clinic.

Generation and evaluation of antibody agents for molecular imaging of CD44v6-expressing cancers

AIM

The aim of this study was to generate and characterize scFv antibodies directed to human CD44v6, as well as to radiolabel and evaluate top candidates in vitro and in vivo for their potential use in CD44v6-targeted molecular imaging in cancer patients.

MATERIALS AND METHODS

Phage display selections were used to isolate CD44v6-specific scFvs. A chain shuffling strategy was employed for affinity maturation based on a set of CD44v6-specific first-generation clones. Two second-generation scFv clones were then chosen for labeling with 111In or 125I and assessed for CD44v6-specific binding on cultured tumor cells. In vivo uptake and distribution was evaluated in tumor-bearing mice using a dual tumor model. Finally, a proof-of-concept small animal PET-CT study was performed on one of the candidates labeled with 124I.

RESULTS

Two affinity-matured clones, CD44v6-scFv-A11 and CD44v6-scFv-H12, displayed promising binding kinetics. Seven out of eight radiolabeled conjugates demonstrated CD44v6-specific binding. In vivo studies on selected candidates demonstrated very advantageous tumor-to-organ ratios, in particular for iodinated conjugates, where 125I-labeled scFvs exhibited favorable kinetics and tumor-to-blood ratios above five already at 24 hours p.i.. The small animal PET-CT study using 124I-labeled CD44v6-scFv-H12 was in line with the biodistribution data, clearly visualizing the high CD44v6-expressing tumor.

CONCLUSION

The single chain fragments, CD44v6-scFv-A11 and CD44v6-scFv-H12 specifically bind to CD44v6, and the radiolabeled counterparts provide high tumor-to-blood ratios and fast clearance from organs and blood. We conclude that radioiodinated CD44v6-scFv-A11 and CD44v6-scFv-H12 possess features highly suitable for stringent molecular imaging.

An oral administration of a recombinant anti-TNF fusion protein is biologically active in the gut promoting regulatory T cells: Results of a phase I clinical trial using a novel oral anti-TNF alpha-based therapy

BACKGROUND

An orally administered BY-2 plant cell-expressed recombinant anti-TNF fusion protein (PRX-106) consists of the soluble form of the human TNF receptor (TNFR) fused to the Fc component of a human IgG1 domain. Aim This study aim at determining the safety and the immune modulatory effect of an oral administration of PRX-106 in humans.

METHODS

Three different doses (2, 8 or 16mg/day) of PRX-106 were orally administered for five consecutive days in 14 healthy volunteered participants. Subjects were followed for safety parameters and for an effect on T lymphocytes subsets and cytokine levels.

RESULTS

An oral administration of PRX-106 was safe and well tolerated. The PK study showed that PRX106 is not absorbed. No effect on white blood cells and lymphocytes counts were noted. A dose dependent effect was noted on systemic lymphocytes. The oral administration of all three dosages was associated with an increase in CD4+CD25+ and CD8+CD25+ subset of suppressor lymphocytes. A marked increase in CD4+CD25+FoxP3 regulatory T cells was noted in the 8mg treated group. In addition, NKT regulatory cells, CD3+CD69+ and CD4+CD62 lymphocyte subsets increased with treatment. No changes in serum TNF alpha were observed.

CONCLUSION

An oral administration of the non-absorbable recombinant anti-TNF fusion protein, PRX-106, is safe, not associated with immune suppression, while inducing a favorable anti-inflammatory immune modulation. The PRX-106 may provide a safe orally administered effective anti-TNF alpha-based immune therapy for inflammatory bowel diseases and non-alcoholic steatohepatitis, as well as other autoimmune, TNF-mediated diseases.

Molecular imaging of the tumor microenvironment

The tumor microenvironment plays a critical role in tumor initiation, progression, metastasis, and resistance to therapy. It is different from normal tissue in the extracellular matrix, vascular and lymphatic networks, as well as physiologic conditions. Molecular imaging of the tumor microenvironment provides a better understanding of its function in cancer biology, and thus allowing for the design of new diagnostics and therapeutics for early cancer diagnosis and treatment. The clinical translation of cancer molecular imaging is often hampered by the high cost of commercialization of targeted imaging agents as well as the limited clinical applications and small market size of some of the agents. Because many different cancer types share similar tumor microenvironment features, the ability to target these biomarkers has the potential to provide clinically translatable molecular imaging technologies for a spectrum of cancers and broad clinical applications. There has been significant progress in targeting the tumor microenvironment for cancer molecular imaging. In this review, we summarize the principles and strategies of recent advances made in molecular imaging of the tumor microenvironment, using various imaging modalities for early detection and diagnosis of cancer.

Anticalins directed against vascular endothelial growth factor receptor 3 (VEGFR-3) with picomolar affinities show potential for medical therapy and in vivo imaging

Members of the vascular endothelial growth factor receptor (VEGFR) family play a central role in angiogenesis as well as lymphangiogenesis and are crucial for tumor growth and metastasis. In particular, VEGFR-3 expression is induced in endothelial cells during tumor angiogenesis. We report the design of anticalins that specifically recognize the ligand-binding domains 1 and 2 of VEGFR-3. To this end, a library of the lipocalin 2 scaffold with 20 randomized positions distributed across its binding site was subjected to phage display selection and enzyme linked immunosorbent assay (ELISA) screening using the VEGF-C binding fragment (D1-2) or the entire extracellular region (D1-7) of VEGFR-3 as target proteins. Promising anticalin candidates were produced in Escherichia coli and biochemically characterized. Three variants with different receptor binding modes were identified, and two of them were optimized with regard to target affinity as well as folding efficiency. The resulting anticalins show dissociation constants down to the single-digit picomolar range. Specific recognition of VEGFR-3 on cells was demonstrated by immunofluorescence microscopy. Competitive binding versus VEGF-C was demonstrated for two of the anticalins with Ki values in the low nanomolar range. Based on these data, VEGFR-3 specific anticalins provide promising reagents for the diagnosis and/or therapeutic intervention of tumor-associated vessel growth.

Iron oxide nanoparticle surface decorated with cRGD peptides for magnetic resonance imaging of brain tumors

In this article, a specific targeting Magnetic Resonance Imaging (MRI) nanoplatform, composed by iron oxide nanoparticle (NP) with cRGD peptides as targeting agent onto NP surface, is explored for the diagnosis of brain tumors by MRI using intracranial U87MG mice xenograft tumor. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editor: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader.

Review article: novel methods for the treatment of non-alcoholic steatohepatitis - targeting the gut immune system to decrease the systemic inflammatory response without immune suppression

BACKGROUND

The systemic immune system plays a role in inflammation and fibrogenesis associated with non-alcoholic steatohepatitis (NASH) and has become a potential target for drug development. In particular, the gut immune system has been suggested as a means for generating signals that can target the systemic immune system.

AIM

To describe seven novel methods being developed for the treatment of NASH that target the gut immune system for alleviation of the systemic inflammatory response, including oral administration of fatty-liver-derived proteins, anti-CD3 antibodies, tumour necrosis factor fusion protein, anti-lipopolysaccharide antibodies, glucosylceramide, delayed-release mercaptopurine, and soy-derived extracts.

METHODS

A search for these methods for oral immunotherapy for NASH was conducted.

RESULTS

Oral administration of these compounds provides an opportunity for immune modulation without immune suppression, with the advantage of being independent of a single molecular/inflammatory pathway. These modes of oral immune therapy demonstrate superior safety profiles, such that the patient is not exposed to general immune suppression. Moreover, these approaches target the whole spectrum of the disease and may serve as adjuvants to other therapies, such that they provide a platform for treatment of concomitant disorders in patients with NASH, including diabetes and hyperlipidaemia. Most of the compounds reviewed are currently in phase II trials, and it is anticipated that the acquisition of more clinical data in the next few years will enable the use of this new class of drugs for the treatment of NASH.

CONCLUSION

Oral immunotherapy may provide a novel platform for the treatment of NASH.

In vivo targeting of metastatic breast cancer via tumor vasculature-specific nano-graphene oxide

Angiogenesis, i.e. the formation of neovasculatures, is a critical process during cancer initiation, progression, and metastasis. Targeting of angiogenic markers on the tumor vasculature can result in more efficient delivery of nanomaterials into tumor since no extravasation is required. Herein we demonstrated efficient targeting of breast cancer metastasis in an experimental murine model with nano-graphene oxide (GO), which was conjugated to a monoclonal antibody (mAb) against follicle-stimulating hormone receptor (FSHR). FSHR has been confirmed to be a highly selective tumor vasculature marker, which is abundant in both primary and metastatic tumors. These functionalized GO nano-conjugates had diameters of ∼120 nm based on atomic force microscopy (AFM), TEM, and dynamic laser scattering (DLS) measurement. (64)Cu was incorporated as a radiolabel which enabled the visualization of these GO conjugates by positron emission tomography (PET) imaging. Breast cancer lung metastasis model was established by intravenous injection of click beetle green luciferase-transfected MDA-MB-231 (denoted as cbgLuc-MDA-MB-231) breast cancer cells into female nude mice and the tumor growth was monitored by bioluminescence imaging (BLI). Systematic in vitro and in vivo studies have been performed to investigate the stability, targeting efficacy and specificity, and tissue distribution of GO conjugates. Flow cytometry and fluorescence microscopy examination confirmed the targeting specificity of FSHR-mAb attached GO conjugates against cellular FSHR. More potent and persistent uptake of (64)Cu-NOTA-GO-FSHR-mAb in cbgLuc-MDA-MB-231 nodules inside the lung was witnessed when compared with that of non-targeted GO conjugates ((64)Cu-NOTA-GO). Histology evaluation also confirmed the vasculature accumulation of GO-FSHR-mAb conjugates in tumor at early time points while they were non-specifically captured in liver and spleen. In addition, these GO conjugates can serve as good drug carriers with satisfactory drug loading capacity (e.g. for doxorubicin [DOX], 756 mg/g). Enhanced drug delivery efficiency in cbgLuc-MDA-MB-231 metastatic sites was demonstrated in DOX-loaded GO-FSHR-mAb by fluorescence imaging. This FSHR-targeted, GO-based nanoplatform can serve as a useful tool for early metastasis detection and targeted delivery of therapeutics.

Effect of charge localization on the in vivo optical imaging properties of near-infrared cyanine dye/monoclonal antibody conjugates

Near-infrared (NIR) fluorophores show superior in vivo imaging properties than visible-light fluorophores because of the increased light penetration in tissue and lower autofluorescence of these wavelengths. We have recently reported that new NIR cyanine dyes containing a novel C4'-O-alkyl linker exhibit greater chemical stability and excellent optical properties relative to existing C4'-O-aryl variants. In this study, we synthesized two NIR cyanine dyes with the same core structure and charge but different indolenine substituents: FNIR-Z-759 bearing a combination of two sulfonates and two quaternary ammonium cations, and FNIR-G-765 bearing a combination of two sulfonates and two guanidines, resulting in zwitterionic charge with distinct cationic moieties. In this study, we compare the in vitro and in vivo optical imaging properties of monoclonal antibody (mAb) conjugates of FNIR-Z-759 and FNIR-G-765 with panitumumab (pan) at antibody-to-dye ratios of 1 : 2 or 1 : 5. One-to-five conjugation of pan-to-FNIR-G-765 was not successful due to aggregate formation during the conjugation reaction. Conjugates of both dyes to pan (2 : 1) demonstrated similar quenching capacity, stability, and brightness in target cells in vitro. However, FNIR-Z-759 conjugates showed significantly lower accumulation in the mouse liver, resulting in higher tumor-to-liver ratio. Thus, FNIR-Z-759 conjugates appear to have superior in vivo imaging characteristics compared with FNIR-G-765 conjugates, especially in the abdominal region. Moreover, from a chemistry point of view, mAb conjugation with FNIR-Z-759 has an advantage over FNIR-G-765, because it does not form aggregates at high dye-to-mAb ratio. These results suggest that zwitterionic cyanine dyes are a superior class of fluorophores for conjugating with mAbs for fluorescence imaging applications due to improving target-to-background contrast in vivo. However, zwitterionic cyanine dyes should be designed carefully, as small changes to the structure can alter in vivo pharmacokinetics of mAb-dye conjugates.

Tumour imaging by the detection of fibrin clots in tumour stroma using an anti-fibrin Fab fragment

The diagnosis of early and aggressive types of cancer is important for providing effective cancer therapy. Cancer-induced fibrin clots exist only within lesions. Previously, we developed a monoclonal antibody (clone 102-10) that recognizes insoluble fibrin but not fibrinogen or soluble fibrin and confirmed that fibrin clots form continuously in various cancers. Here, we describe the development of a Fab fragment probe of clone 102-10 for tumour imaging. The distribution of 102-10 Fab was investigated in genetically engineered mice bearing pancreatic ductal adenocarcinoma (PDAC), and its effect on blood coagulation was examined. Immunohistochemical and ex vivo imaging revealed that 102-10 Fab was distributed selectively in fibrin clots in PDAC tumours 3 h after injection and that it disappeared from the body after 24 h. 102-10 Fab had no influence on blood coagulation or fibrinolysis. Tumour imaging using anti-fibrin Fab may provide a safe and effective method for the diagnosis of invasive cancers by detecting fibrin clots in tumour stroma.

In vivo optical imaging of MMP2 immuno protein antibody: tumor uptake is associated with MMP2 activity

Matrix metalloproteinase-2 (MMP2) is important in tumorigenesis, angiogenesis and tumor invasion. In this study, we investigated if the Cy5-tagged small immuno protein targeting the catalytic domain of human MMP2 (aMMP2-SIP) detects MMP2 in tumors non-invasively. For this purpose, we generated MMP2 expressing (empty vector EV) and knock-down (KD) HT1080, U373 and U87 cells, which were injected subcutaneously in the lateral flank of NMRI-nu mice. Optical imaging (Optix MX2) performed at 0.5, 2, 4, 8, 24 and 48 hour post injection (h.p.i.) of Cy5 tagged aMMP2-SIP, indicated significantly lower tumor to background ratios at both 24 (P = 0.0090) and 48 h.p.i. (P < 0.0001) for the U87 MMP2-KD compared to control tumors. No differences were found for HT1080 and U373 models. U87 MMP2-KD tumors had significantly lower MMP2 activity (P < 0.0001) than EV tumors as determined by gelatin zymography in tumor sections and lysates, while no differences were observed between EV and MMP2-KD in HT1080 and U373. In line with these data, only U87 MMP2-KD tumors had a reduced tumor growth compared to control tumors (P = 0.0053). aMMP2-SIP uptake correlates with MMP2 activity and might therefore be a potential non-invasive imaging biomarker for the evaluation of MMP2 activity in tumors.

Fluorescence Imaging of Inflammation in Live Animals

Inflammation is associated with many diseases, such as stroke, cancer, and atherosclerosis. Noninvasive in vivo monitoring of inflammation can provide deeper understanding of such diseases, which might help to develop better treatment. Inflammation normally causes neutrophils and macrophages to generate reactive oxygen species (ROS) as the destruction tool, which can be used as a biomarker for inflammation. Near-infrared (NIR) window is optimal for in vivo fluorescence imaging owing to the reduced autofluorescence and low attenuation of light in biological tissues. Among NIR fluorescent probes, activatable probes have the promise of achieving high imaging contrast. In this chapter, we describe the method for in vivo fluorescence imaging of inflammation using a ROS-activatable NIR probe.

Deglycosylation of mAb by EndoS for improved molecular imaging

PURPOSE

Monoclonal antibodies (mAbs) have been shown preclinically as reliable targeting moieties for antigen imaging using near-infrared fluorescence (NIRF) molecular imaging. However, crystallizable fragment-gamma receptor (FcγRs) expressed on immune cells also bind mAbs through defined epitopes on the constant fragment (Fc) of IgG. Herein, we evaluate the potential impact Fc interactions have on mAb agent imaging specificity.

PROCEDURE

Through the removal of conserved glycans within the Fc domain, shown to have Fc/FcγR interactions, we evaluate their impact on non-specific binding/accumulation of a NIRF-labeled mAb-based imaging agent in lymph nodes (LNs) in inflamed animals and in an orthotopic prostate cancer animal model of LN metastasis.

RESULTS

Deglycosylation of a murine mAb against the human epithelial cell adhesion marker using endoglycosidase EndoS significantly reduced non-specific binding in the LNs of inflamed animals and in cancer-negative LNs of tumor-bearing animals. Sensitivity remained unchanged while improvement in imaging specificity increased imaging accuracy.

CONCLUSION

The reduction of non-specific binding through deglycosylation of a mAb-based imaging agent shows that reducing Fc/FcγR interactions can improve imaging accuracy.

Stromal Targets for Fluorescent-Guided Oncologic Surgery

Pre-operative imaging techniques are essential for tumor detection and diagnosis, but offer limited help during surgery. Recently, the applicability of imaging during oncologic surgery has been recognized, using near-infrared fluorescent dyes conjugated to targeting antibodies, peptides, or other vehicles. Image-guided oncologic surgery (IGOS) assists the surgeFon to distinguish tumor from normal tissue during operation, and can aid in recognizing vital structures. IGOS relies on an optimized combination of a dedicated fluorescent camera system and specific probes for targeting. IGOS probes for clinical use are not widely available yet, but numerous pre-clinical studies have been published and clinical trials are being established or prepared. Most of the investigated probes are based on antibodies or peptides against proteins on the membranes of malignant cells, whereas others are directed against stromal cells. Targeting stroma cells for IGOS has several advantages. Besides the high stromal content in more aggressive tumor types, the stroma is often primarily located at the periphery/invasive front of the tumor, which makes stromal targets particularly suited for imaging purposes. Moreover, because stroma up-regulation is a physiological reaction, most proteins to be targeted on these cells are “universal” and not derived from a specific genetic variation, as is the case with many upregulated proteins on malignant cancer cells.