Explore the vast range of titles available.

In nature, specific antibodies can be generated as a result of an adaptive selection and expansion of lymphocytes with suitable protein binding properties. We attempted to mimic antibody–antigen recognition by displaying multiple chemical diversity elements on a defined macrocyclic scaffold. Encoding of the displayed combinations was achieved using distinctive DNA tags, resulting in a library size of 35,393,112. Specific binders could be isolated against a variety of proteins, including carbonic anhydrase IX, horseradish peroxidase, tankyrase 1, human serum albumin, alpha-1 acid glycoprotein, calmodulin, prostate-specific antigen and tumour necrosis factor. Similar to antibodies, the encoded display of multiple chemical elements on a constant scaffold enabled practical applications, such as fluorescence microscopy procedures or the selective in vivo delivery of payloads to tumours. Furthermore, the versatile structure of the scaffold facilitated the generation of protein-specific chemical probes, as illustrated by photo-crosslinking.

We describe the development of OncoFAP, an ultra-high-affinity ligand of fibroblast activation protein (FAP) for targeting applications with pan-tumoral potential. OncoFAP binds to human FAP with affinity in the subnanomolar concentration range and cross-reacts with the murine isoform of the protein. We generated various fluorescent and radiolabeled derivatives of OncoFAP in order to study biodistribution properties and tumor-targeting performance in preclinical models. Fluorescent derivatives selectively localized in FAP-positive tumors implanted in nude mice with a rapid and homogeneous penetration within the neoplastic tissue. Quantitative in vivo biodistribution studies with a lutetium-177–labeled derivative of OncoFAP revealed a preferential localization in tumors at doses of up to 1,000 nmol/kg. More than 30% of the injected dose had already accumulated in 1 g of tumor 10 min after intravenous injection and persisted for at least 3 h with excellent tumor-to-organ ratios. OncoFAP also served as a modular component for the generation of nonradioactive therapeutic products. A fluorescein conjugate mediated a potent and FAP-dependent tumor cell killing activity in combination with chimeric antigen receptor (CAR) T cells specific to fluorescein. Similarly, a conjugate of OncoFAP with the monomethyl auristatin E-based Vedotin payload was well tolerated and cured tumor-bearing mice in combination with a clinical-stage antibody-interleukin-2 fusion. Collectively, these data support the development of OncoFAP-based products for tumor-targeting applications in patients with cancer.

The encoding of chemical compounds with amplifiable DNA tags facilitates the discovery of small-molecule ligands for proteins. To investigate the impact of stereo- and regiochemistry on ligand discovery, we synthesized a DNA-encoded library of 670,752 derivatives based on 2-azido-3-iodophenylpropionic acids. The library was selected against multiple proteins and yielded specific ligands. The selection fingerprints obtained for a set of protein targets of pharmaceutical relevance clearly showed the preferential enrichment of ortho-, meta- or para-regioisomers, which was experimentally verified by affinity measurements in the absence of DNA. The discovered ligands included novel selective enzyme inhibitors and binders to tumour-associated antigens, which enabled conditional chimeric antigen receptor T-cell activation and tumour targeting.A DNA-encoded chemical library based on regio- and stereoisomers of phenylalanine has been synthesized and used for affinity-based selections against multiple target proteins. This approach led to the isolation and validation of potent ligands capable of CAR T-cell activation and tumour targeting.

Cyclic peptides constitute an important drug modality since they offer significant advantages over small molecules and macromolecules. However, access to diverse chemical sets of cyclic peptides is difficult on a large library scale. DNA-encoded Chemical Libraries (DELs) provide a suitable tool to obtain large chemical diversity, but cyclic DELs made by standard DEL implementation cannot efficiently explore their conformational diversity. On the other hand, dual-display Encoded Self-Assembling Chemical (ESAC) Libraries can be used for modulating macrocycle flexibility since the two displayed peptides can be connected in an incremental fashion. In this work, we construct a 56 million dual-display ESAC library using a two-step cyclization strategy. We show that varying the level of conformational restraint is essential for the discovery of specific ligands for the three protein targets thrombin, human alkaline phosphatase and streptavidin. Cyclic peptides are an important drug modality but access to diverse chemical sets of cyclic peptides is difficult on a large library scale. Here, the authors use DNA-encoded library (DEL) technology for the dual-display of two peptidic sub-libraries at the extremities of DNA heteroduplexes and show that varying the level of conformational restraint is essential for the discovery of specific ligands for the three protein targets.

DNA‐encoded chemical libraries (DELs) are powerful tools for drug discovery, enabling the high‐throughput screening of vast libraries of small molecules against target proteins of pharmaceutical interest. Here, the synthesis of two new DELs, named FM‐DEL1 and FM‐DEL2, including 7′710 and 5′697’690 compounds, respectively is described. These libraries are constructed by installing one or two sets of building blocks on a phenylalanine central scaffold. FM‐DELs are screened against markers of prostate cancer, and renal cell carcinoma, and against an immunological target expressed on the surface of natural killer cells. Highly potent and selective binders with affinity constants in the nanomolar range are obtained from DEL screenings against those targets. Small‐molecule ligands against tumor‐associated antigens are used to develop small‐molecule radiopharmaceuticals that selectively accumulate at cancer sites after systemic administration. FM‐DEL1 and FM‐DEL2 are constructed by installing one or two sets of building blocks on a phenylalanine central scaffold. FM‐DELs are screened against markers of prostate, and renal cell carcinoma, and against an immunological target expressed on the surface of natural killer cells. Highly potent and selective binders with affinity constants in the nanomolar range are isolated for those targets.

FAP-targeted radiopharmaceuticals represent a breakthrough in cancer imaging and a viable option for therapeutic applications. OncoFAP is an ultra-high-affinity ligand of FAP with a dissociation constant of 680 pM. OncoFAP has been recently discovered and clinically validated for PET imaging procedures in patients with solid malignancies. While more and more clinical validation is becoming available, the need for scalable and robust procedures for the preparation of this new class of radiopharmaceuticals continues to increase. In this article, we present the development of automated radiolabeling procedures for the preparation of OncoFAP-based radiopharmaceuticals for cancer imaging and therapy. A new series of [68Ga]Ga-OncoFAP, [177Lu]Lu-OncoFAP and [18F]AlF-OncoFAP was produced with high radiochemical yields. Chemical and biochemical characterization after radiolabeling confirmed its excellent stability, retention of high affinity for FAP and absence of radiolysis by-products. The in vivo biodistribution of [18F]AlF-NOTA-OncoFAP, a candidate for PET imaging procedures in patients, was assessed in mice bearing FAP-positive solid tumors. The product showed rapid accumulation in solid tumors, with an average of 6.6% ID/g one hour after systemic administration and excellent tumor-to-healthy organs ratio. We have developed simple, quick, safe and robust synthetic procedures for the preparation of theranostic OncoFAP-compounds based on Gallium-68, Lutetium-177 and Fluorine-18 using the commercially available FASTlab synthesis module.

Immune-stimulating antibody conjugates (ISACs) equipped with imidazoquinoline (IMD) payloads can stimulate endogenous immune cells to kill cancer cells, ultimately inducing long-lasting anticancer effects. A novel ISAC was designed, featuring the IMD Resiquimod (R848), a tumor-targeting antibody specific for Carbonic Anhydrase IX (CAIX) and the protease-cleavable Val-Cit-PABC linker. In vitro stability analysis showed not only R848 release in the presence of the protease Cathepsin B but also under acidic conditions. The ex vivo mass spectrometry-based biodistribution data confirmed the low stability of the linker-drug connection while highlighting the selective accumulation of the IgG in tumors and its long circulatory half-life.

Fibroblast activation protein (FAP) is involved in the extracellular matrix (ECM) remodeling and wound healing. Absent in most adult tissues, it is overexpressed by neoplastic cells and/or cancer-associated fibroblasts (CAFs) in several human malignancies. The extra Domain-B of fibronectin (EDB+FN) is a splice variant of fibronectin involved in angiogenesis and tissue remodeling, overexpressed by CAFs and cancer-associated vessels (CAVs) in many aggressive human tumors. This study aims to investigate FAP and EDB+FN expressions in canine tumors and assess their potential as druggable targets in animal patients. FAP and EDB+FN expression was assessed by immunohistochemistry on 88 canine tumors, including Soft Tissue Sarcomas [STS], Osteosarcomas [OSA], Hemangiosarcomas [HSA], Apocrine Gland Anal Sac Adenocarcinomas [AGASAC], Mast Cell Tumors [MCT], Lymphomas, and Melanomas, using polyclonal and monoclonal anti-FAP and the L19 anti-EDB antibodies. Expression distribution and intensity were semi-quantitatively scored in neoplastic cells, CAFs, CAVs, and stroma. FAP was variably expressed in neoplastic cells (79/88), CAFs (79/88), and CAVs (82/88) across all tumor types, but mostly in AGASACs, STSs, and MCTs. The monoclonal antibody presented greater specificity. EDB+FN expression was less present across tumor types, mostly with a vascular staining pattern. Labelling was most intense and consistent in the neoplastic cells, CAFs, and CAVs of melanomas, and to a lesser extent in AGASAC and STS. STS, AGASAC, and MCT could be candidates for FAP-targeted strategies; melanomas are the most promising for EDB+FN-directed therapies. These results support FAP and EDB+FN as targets worth investigating for clinical applications in animal patients.

Purpose 177 Lu-OncoFAP-23 is a novel FAP-targeted radioligand therapeutic (RLT) with high and prolonged tumor residence time and promising preclinical efficacy. In this work, we investigated the correlation between the injected molar dose and the in vivo tumor-to-organ ratios and tumor-targeting performance of 177 Lu-OncoFAP-23. Methods We evaluated the quantitative biodistribution profile of 177 Lu-OncoFAP-23 at different molar doses (i.e., 3 to 2250 nmol/kg) in tumor-bearing mice by means of ex vivo gamma counting, we included 177 Lu-OncoFAP and 177 Lu-BiOncoFAP as experimental controls. Results The biodistribution profile of 177 Lu-OncoFAP-23 strongly depends on the molar dose injected. Molar doses below 30 nmol/kg result in unwanted uptake of the compound in healthy organs, while doses higher than 725 nmol/kg determined a reduced tumor uptake due to receptor saturation. We identified an optimal molar dose ranging from 90 to 250 nmol/kg, characterized by elevated tumor uptake and adequate tumor-to-organ ratios. Conclusion 177 Lu-OncoFAP-23 presents a favorable in vivo biodistribution profile at molar doses ranging from 90 to 250 nmol/kg in tumor-bearing mice. Our results guide the design of the first-in-human Phase I clinical trial with this novel FAP-targeted radioligand therapeutic. Graphical abstract