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Diffuse gliomas comprise a group of primary brain tumors that originate from glial (precursor) cells and present as a variety of malignancy grades which have in common that they grow by diffuse infiltration. This phenotype complicates treatment enormously as it precludes curative surgery and radiotherapy. Furthermore, diffusely infiltrating glioma cells often hide behind a functional blood-brain barrier, hampering delivery of systemically administered therapeutic and diagnostic compounds to the tumor cells. The present review addresses the biological mechanisms that underlie the diffuse infiltrative phenotype, knowledge of which may improve treatment strategies for this disastrous tumor type. The invasive phenotype is specific for glioma: most other brain tumor types, both primary and metastatic, grow as delineated lesions. Differences between the genetic make-up of glioma and that of other tumor types may therefore help to unravel molecular pathways, involved in diffuse infiltrative growth. One such difference concerns mutations in the NADP+-dependent isocitrate dehydrogenase (IDH1 and IDH2) genes, which occur in > 80% of cases of low grade glioma and secondary glioblastoma. In this review we present a novel hypothesis which links IDH1 and IDH2 mutations to glutamate metabolism, possibly explaining the specific biological behavior of diffuse glioma. [ABSTRACT FROM AUTHOR]

Hypoxic areas are present in the majority of solid tumors, and hypoxia is associated with resistance to therapies and poor outcomes. A transmembrane protein that is upregulated by tumor cells that have adapted to hypoxic conditions is carbonic anhydrase IX (CAIX). Therefore, noninvasive imaging of CAIX could be of prognostic value, and it could steer treatment strategies. The aim of this study was to compare variants of CAIX-binding VHH B9, with and without a C-terminal albumin-binding domain with varying affinity (ABD low and ABD high ), for SPECT imaging of CAIX expression. The binding affinity and internalization of the various B9-variants were analyzed using SK-RC-52 cells. Biodistribution studies were performed in mice with subcutaneous SCCNij153 human head and neck cancer xenografts. Tracer uptake was determined by ex vivo radioactivity counting and visualized by SPECT/CT imaging. Furthermore, autoradiography images of tumor sections were spatially correlated with CAIX immunohistochemistry. B9-variants demonstrated a similar moderate affinity for CAIX in vitro . Maximal tumor uptake and acceptable tumor-to-blood ratios were found in the SCCNij153 model at 4 h post injection for [ 111 In]In-DTPA-B9 (0.51 ± 0.08%ID/g and 8.1 ± 0.85, respectively), 24 h post injection for [ 111 In]In-DTPA-B9-ABD low (2.39 ± 0.44%ID/g and 3.66 ± 0.81, respectively) and at 72 h post injection for [ 111 In]In-DTPA-B9-ABD high (8.7 ± 1.34%ID/g and 2.43 ± 0.15, respectively) . An excess of unlabeled monoclonal anti-CAIX antibody efficiently inhibited tumor uptake of [ 111 In]In-DTPA-B9, while only a partial reduction of [ 111 In]In-DTPA-B9-ABD low and [ 111 In]In-DTPA-B9-ABD high uptake was found. Immunohistochemistry and autoradiography images showed colocalization of all B9-variants with CAIX expression; however, [ 111 In]In-DTPA-B9-ABD low and [ 111 In]In-DTPA-B9-ABD high also accumulated in non-CAIX expressing regions. Tumor uptake of [ 111 In]In-DTPA-B9-ABD low and [ 111 In]In-DTPA-B9-ABD high , but not of [ 111 In]In-DTPA-B9, could be visualized with SPECT/CT imaging. In conclusion, [ 111 In]In-DTPA-B9 has a high affinity to CAIX and shows specific targeting to CAIX in head and neck cancer xenografts. The addition of ABD prolonged plasma half-life, increased tumor uptake, and enabled SPECT/CT imaging. This uptake was, however, partly CAIX- independent, precluding the ABD-tracers for use in hypoxia quantification in this tumor type.

Insulinomas, neuroendocrine tumors arising from pancreatic beta cells, often show overexpression of the glucagon-like peptide-1 receptor. Therefore, imaging with glucagon-like peptide analog exendin-4 can be used for diagnosis and preoperative localization. This review presents an overview of the development and clinical implementation of exendin-based tracers for nuclear imaging, and the potential use of exendin-4 based tracers for optical imaging and therapeutic applications such as peptide receptor radionuclide therapy or targeted photodynamic therapy., (© 2019 The Authors Journal of Labelled Compounds and Radiopharmaceuticals Published by John Wiley & Sons Ltd.)

Photodynamic therapy (PDT) is an emerging method to treat light-accessible malignancies. To increase specificity and allow dose reduction, conjugates of photosensitizers (PS) with antibodies against tumor-associated antigens have been developed for photoimmunotherapy (PIT). However, so far it is unclear whether cellular internalization of these conjugates after binding affects PIT efficacy. The use of low molecular weight llama single domain antibodies (VHHs, nanobodies) for PIT is preferred above full size antibodies because of better tumor penetration. Therefore, we functionalized the VHH 7D12, directed against the epidermal growth factor receptor (EGFR), with a PS (IRDye700DX). To assess the impact of cellular internalization on activity, the VHHs were additionally conjugated to a cell-penetrating peptide (VHH [PS] -CPP). Here we show that upon illumination with near-infrared (NIR) light, both VHH [PS] and VHH [PS] -CPP conjugates specifically induce cell death of EGFR expressing cancer cell lines and of EGFR-expressing cells derived from surgically obtained ascites from patients with high-grade serous ovarian cancer. However, VHH [PS] conjugates were significantly more effective compared to internalizing VHH [PS] -CPP suggesting that cell surface association is required for optimal therapeutic activity., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

Epithelial ovarian cancer is characterized by a high mortality rate and is in need for novel therapeutic avenues to improve patient outcome. The tumor's extracellular matrix ("stroma") offers new possibilities for targeted drug-delivery. Recently we identified highly sulfated chondroitin sulfate (CS-E) as a component abundantly present in the ovarian cancer extracellular matrix, and as a novel target for anti-cancer therapy. Here, we report on the functionalization of drug-loaded lyophilisomes (albumin-based biocapsules) to specifically target the stroma of ovarian carcinomas with the potential to eliminate cancer cells. To achieve specific targeting, we conjugated single chain antibodies reactive with CS-E to lyophilisomes using a two-step approach comprising sortase-mediated ligation and bioorthogonal click chemistry. Antibody-functionalized lyophilisomes specifically targeted the ovarian cancer stroma through CS-E. In a CS-E rich micro-environment in vitro lyophilisomes induced cell death by extracellular release of doxorubicin which localized to the nucleus. Immunohistochemistry identified CS-E rich stroma in a variety of solid tumors other than ovarian cancer, including breast, lung and colon cancer indicating the potential versatility of matrix therapy and the use of highly sulfated chondroitin sulfates in cancer stroma as a micro-environmental hook for targeted drug delivery., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)

Diffuse gliomas are primary brain cancers that are characterised by infiltrative growth. Whereas high-grade glioma characteristically presents with perinecrotic neovascularisation, large tumor areas thrive on pre-existent vasculature as well. Clinical studies have revealed that pharmacological inhibition of the angiogenic process does not improve survival of glioblastoma patients. Direct targeting of tumor vessels may however still be an interesting therapeutic approach as it allows pinching off the blood supply to tumor cells. Such tumor vessel targeting requires the identification of tumor-specific vascular targeting agents (TVTAs).Here we describe a novel TVTA, C-C7, which we identified via in vivo biopanning of a llama nanobody phage display library in an orthotopic mouse model of diffuse glioma. We show that C-C7 recognizes a subpopulation of tumor blood vessels in glioma xenografts and clinical glioma samples. Additionally, C-C7 recognizes macrophages and activated endothelial cells in atherosclerotic lesions. By using C-C7 as bait in yeast-2-hybrid (Y2H) screens we identified dynactin-1-p150Glued as its binding partner. The interaction was confirmed by co-immunostainings with C-C7 and a commercial anti-dynactin-1-p150Glued antibody, and via co-immunoprecipitation/western blot studies. Normal brain vessels do not express dynactin-1-p150Glued and its expression is reduced under anti-VEGF therapy, suggesting that dynactin-1-p150Glued is a marker for activated endothelial cells.In conclusion, we show that in vivo phage display combined with Y2H screenings provides a powerful approach to identify tumor-targeting nanobodies and their binding partners. Using this combination of methods we identify dynactin-1-p150Glued as a novel targetable protein on activated endothelial cells and macrophages.