Clickable Radiocomplexes With Trivalent Radiometals for Cancer Theranostics: In vitro and in vivo Studies

Pre-targeting approaches based on the inverse-electron-demand Diels-Alder (iEDDA) reaction between strained trans-cyclooctenes (TCO) and electron-deficient tetrazines (Tz) have emerged in recent years as valid alternatives to classic targeted strategies to improve the diagnostic and therapeutic properties of radioactive probes. To explore these pre-targeting strategies based on in vivo click chemistry, a small family of clickable chelators was synthesized and radiolabelled with medically relevant trivalent radiometals. The structure of the clickable chelators was diversified to modulate the pharmacokinetics of the resulting [111In]In-radiocomplexes, as assessed upon injection in healthy mice. The derivative DOTA-Tz was chosen to pursue the studies upon radiolabelling with 90Y, yielding a radiocomplex with high specific activity, high radiochemical yields and suitable in vitro stability. The [90Y]Y-DOTA-Tz complex was evaluated in a prostate cancer PC3 xenograft by ex-vivo biodistribution studies and Cerenkov luminescence imaging (CLI). The results highlighted a quick elimination through the renal system and no relevant accumulation in non-target organs or non-specific tumor uptake. Furthermore, a clickable bombesin antagonist was injected in PC3 tumor-bearing mice followed by the radiocomplex [90Y]Y-DOTA-Tz, and the mice imaged by CLI at different post-injection times (p.i.). Analysis of the images 15 min and 1 h p.i. pointed out an encouraging quick tumor uptake with a fast washout, providing a preliminary proof of concept of the usefulness of the designed clickable complexes for pre-targeting strategies. To the best of our knowledge, the use of peptide antagonists for this purpose was not explored before. Further investigations are needed to optimize the pre-targeting approach based on this type of biomolecules and evaluate its eventual advantages

Image-guided nanodelivery of Pt(IV) prodrugs to GRP-receptor positive tumors

Over the last decades, gold nanoparticles (AuNPs) have proven to be remarkable tools for drug delivery and theranostic applications in cancer treatment. On the other hand, Pt(IV) prodrugs have been employed as an interesting alternative to the more common Pt(II) complexes, such as cisplatin, for cancer chemotherapy. Searching to design an image-guided nanocarrier to deliver selectively Pt(IV) prodrugs to tumors expressing the gastrin-releasing peptide receptor (GRPR), we have synthesized small core AuNPs carrying a thiolated DOTA derivative, a GRPR-targeting bombesin analog (BBN[7-14]) and a Pt(IV) prodrug attached to the AuNPs without (AuNP-BBN-Pt1) or with a PEGylated linker (AuNP-BBN-Pt2 and AuNP-BBN-Pt3). In the GRPR+ prostate cancer PC3 cell line, the cytotoxic activity of the designed AuNP-BBN-Pt nanoparticles is strongly influenced by the presence of the PEGylated linker. Thus, AuNP-BBN-Pt1 displayed the lowest IC50 value (9.3 ± 2.3 µM of Pt), which is comparable to that exhibited by cisplatin in the same cell line. In contrast, AuNP-BBN-Pt1 showed an IC50 value of 97 ± 18 µM of Pt in the non-tumoral RWPE-1 prostate cells with a much higher selective index (SI) towards PC3 cells (SI = 10) when compared with cisplatin (SI = 1.3). The AuNPs were also successfully labeled with 67Ga and the resulting 67Ga-AuNP-BBN-Pt were used to assess their cellular uptake in PC3 cells, with AuNP-BBN-Pt1 also displaying the highest cellular internalization. Finally, intratumoral administration of 67Ga-AuNP-BBN-Pt1 in PC3 tumor-bearing mice showed prolonged retention of the nanoparticle compared to that of cisplatin, with optimal in vivo stability and 20% of the injected platinum remaining in the tumor after 72 h post-injection. Furthermore, microSPECT imaging studies confirmed the uptake and considerable retention of the 67Ga-labeled AuNPs in the tumors. Overall, these results show the potential of these targeted AuNPs loaded with Pt(IV) prodrugs for prostate cancer theranostics.info:eu-repo/semantics/publishedVersio

Novel peptides derived from dengue virus capsid protein translocate reversibly the blood−brain barrier through a receptor-free mechanism

© 2017 American Chemical SocietyThe delivery of therapeutic molecules to the central nervous system is hampered by poor delivery across the blood-brain barrier (BBB). Several strategies have been proposed to enhance transport into the brain, including invasive techniques and receptor-mediated transport (RMT). Both approaches have several drawbacks, such as BBB disruption, receptor saturation, and off-target effects, raising safety issues. Herein, we show that specific domains of Dengue virus type 2 capsid protein (DEN2C) can be used as trans-BBB peptide vectors. Their mechanism of translocation is receptor-independent and consistent with adsorptive-mediated transport (AMT). One peptide in particular, named PepH3, reaches equilibrium distribution concentrations across the BBB in less than 24 h in a cellular in vitro assay. Importantly, in vivo biodistribution data with radiolabeled peptide derivatives show high brain penetration. In addition, there is fast clearance from the brain and high levels of excretion, showing that PepH3 is a very good candidate to be used as a peptide shuttle taking cargo in and out of the brain.The authors thank the Portuguese Funding Agency, Fundação para a Ciência e a Tecnologia, FCT IP, for financial support (grants SFRH/BPD/94466/2013; SFRH/BPD/109010/2015; IF/01010/2013; PTDC/BBBNAN/1578/2014; HIVERA/ 0002/2013) and Marie Skłodowska-Curie Research and Innovation Staff Exchange (MSCA-RISE), call 20-MSCARISE-2014 (grant agreement H20 644167 − INPACT). M.M., L.G., C.F., and J.D.G.C. gratefully acknowledge FCT support through the UID/Multi/04349/2013 project.info:eu-repo/semantics/publishedVersio

Dual imaging gold nanoplatforms for targeted radiotheranostics

Gold nanoparticles (AuNPs) are interesting for the design of new cancer theranostic tools, mainly due to their biocompatibility, easy molecular vectorization, and good biological half-life. Herein, we report a gold nanoparticle platform as a bimodal imaging probe, capable of coordinating Gd3+ for Magnetic Resonance Imaging (MRI) and 67Ga3+ for Single Photon Emission Computed Tomography (SPECT) imaging. Our AuNPs carry a bombesin analogue with anity towards the gastrin releasing peptide receptor (GRPr), overexpressed in a variety of human cancer cells, namely PC3 prostate cancer cells. The potential of these multimodal imaging nanoconstructs was thoroughly investigated by the assessment of their magnetic properties, in vitro cellular uptake, biodistribution, and radiosensitisation assays. The relaxometric properties predict a potential T1-and T2-MRI application. The promising in vitro cellular uptake of 67Ga/Gd-based bombesin containing particles was confirmed through biodistribution studies in tumor bearing mice, indicating their integrity and ability to target the GRPr. Radiosensitization studies revealed the therapeutic potential of the nanoparticles. Moreover, the DOTA chelating unit moiety versatility gives a high theranostic potential through the coordination of other therapeutically interesting radiometals. Altogether, our nanoparticles are interesting nanomaterial for theranostic application and as bimodal T1-and T2-MRI / SPECT imaging probes.This research was funded by FCT (Portuguese Foundation for Science and Technology), grant numbers EXCL/QEQ-MED/0233/2012, UID/Multi/04349/2013 and PTDC/MED-QUI/29649/2017. CFGCG and MMCAC thank FCT and FEDER through the COMPETE Program for funding the CQC (UID/QUI/00313/2013 and PEst-OE/QUI/UI0313/2014). P.L-L. thanks Ministry of Economy, Industry and Competitiviy for SAF2017-83043-R, and Comunity of Madrid, FEDER and FSE for S2017/BMD-368

Rabbit derived VL single-domains as promising scaffolds to generate antibody–drug conjugates

© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.Antibody-drug conjugates (ADCs) are among the fastest-growing classes of therapeutics in oncology. Although ADCs are in the spotlight, they still present significant engineering challenges. Therefore, there is an urgent need to develop more stable and effective ADCs. Most rabbit light chains have an extra disulfide bridge, that links the variable and constant domains, between Cys80 and Cys171, which is not found in the human or mouse. Thus, to develop a new generation of ADCs, we explored the potential of rabbit-derived VL-single-domain antibody scaffolds (sdAbs) to selectively conjugate a payload to Cys80. Hence, a rabbit sdAb library directed towards canine non-Hodgkin lymphoma (cNHL) was subjected to in vitro and in vivo phage display. This allowed the identification of several highly specific VL-sdAbs, including C5, which specifically target cNHL cells in vitro and present promising in vivo tumor uptake. C5 was selected for SN-38 site-selective payload conjugation through its exposed free Cys80 to generate a stable and homogenous C5-DAB-SN-38. C5-DAB-SN-38 exhibited potent cytotoxicity activity against cNHL cells while inhibiting DNA-TopoI activity. Overall, our strategy validates a platform to develop a novel class of ADCs that combines the benefits of rabbit VL-sdAb scaffolds and the canine lymphoma model as a powerful framework for clinically translation of novel therapeutics for cancer.This work was supported by the Portuguese Funding Agency, Fundação para a Ciência e Tecnologia, FCT IP (SAICT/2017/32085, PTDC/QUI-OUT/3989/2021 and Ph.D. fellowship SFRH/BD/131468/2017 to ASA and SFRH/BD/90514/2012 to JD). CIISA has provided support through Project UIDB/00276/2020, funded by FCT and LA/P/0059/2020-AL4AnimalS. Research Institute for Medicines (iMed.ULisboa) acknowledges the financial support of Fundação para a Ciência e Tecnologia (Projects: PTDC/QUI-OUT/3989/2021; UIDB/04138/2020 and UIDP/04138/2020). The NMR spectrometers are part of the National NMR Network (PTNMR) and are partially supported by Infrastructure Project Nº 022161 (co-financed by FEDER through COMPETE 2020, POCI and PORL and FCT through PIDDAC).info:eu-repo/semantics/publishedVersio

Bis(3-hydroxy-4-pyridinone)-EDTA derivative as a potential therapeutic Al-chelating agent: synthesis, solution studies and biological assays

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Studies of the myocardial uptake and excretion mechanisms of a novel 99m Tc heart perfusion agent

Abstract Introduction: 99m Tc-TMEOP is a novel heart perfusion radiotracer exhibiting high initial and persistent heart uptake associated with rapid blood and liver clearance. This study aimed at determining the mechanisms of myocardial localization and fast liver clearance of 99m Tc-TMEOP. Methods: Subcellular distribution of 99m Tc-TMEOP was determined in excised rat heart tissue by differential centrifugation. The effect of cyclosporin A on the pharmacokinetic behaviour of 99m Tc-TMEOP was evaluated by both ex vivo biodistribution and in vivo planar imaging studies. Results: Subcellular distribution studies showed that more than 73% of 99m Tc-TMEOP was associated with the mitochondrial fraction. Comparison with subcellular distribution of 99m Tc-sestamibi showed no significant difference in the mitochondrial accumulation between the two tracers. Biodistribution studies in the presence of cyclosporin A revealed an increase in kidneys and liver uptake of 99m Tc-TMEOP, suggesting the involvement of multidrug resistance transporters in determining its pharmacokinetic profile. Conclusions: The heart uptake mechanism of 99m Tc-TMEOP is similar to that of the other reported monocationic 99m Tc cardiac agents and is associated with its accumulation in the mitochondria. Cyclosporin A studies indicate that the fast liver and kidney clearance kinetics is mediated by P-glycoprotein (Pgp), supporting the potential interest of this radiotracer for imaging Pgp function associated with multidrugresistant tumours

Radiochemical and biological behaviour of 153Sm and 166Ho complexes anchored by a novel bis(methylphosphonate) tetraazamacrocycle

International audienceThe novel bis(methylphosphonate) 2,2′-[4,10-bis-(phosphonomemyl)-1,4, 7,10-tetraazacyclododecane-1,7-diyl] diacetic acid, trans-H6DO2A2P, has been synthesized and characterized by multinuclear NMR spectroscopy ( 1H, 13C and 31P). 153Sm and 166Ho complexes with trans-H6DO2A2P have been prepared in high yield using a 1:2 metal to ligand molar ratio at 70°C, pH 8-9. These complexes are hydrophilic, negatively charged and stable in vitro under physiological solutions, up to 48 h. They present a low plasmatic protein binding and some in vitro hydroxyapatite adsorption, mainly for 166Ho-trans-DO2A2P. Both complexes are stable in vivo, have a fast tissue clearance from most organs and a rapid total excretion from whole animal body. Moderate bone uptake was also observed but the accumulated radioactivity rapidly decreases with time

Imaging probes for non-invasive tumoral detection and functional monitoring of cancer multidrug resistance

Aim: Several cationic radiotracers originally developed as myocardial perfusion agents have shown potential for both early detection of cancer and non-invasive monitoring of multiple drug resistance (MDR) by single photon emission computed tomography. We have introduced two cationic complexes, 99mTc-DMEOP [di-methoxy-tris-pyrazolyl-99mTc-(CO)3] and 99mTc-TMEOP [tri-methoxy-tris-pyrazolyl-99mTc-(CO)3], which showed excellent preclinical results as cardiac imaging probes, namely a persistent heart uptake with rapid blood and liver clearance. This study aimed at the evaluation of their usefulness for tumoral detection and functional assessment of MDR.Methods: The uptake and efflux kinetics of 99mTc-DMEOP and 99mTc-TMEOP were evaluated in human prostate, lung, and breast cancer cell lines, including drug-resistant cell lines that are known to overexpress the MDR P-glycoprotein (Pgp). The effects of MDR modulators were also studied. In vivo studies were performed in xenografted tumor models, and the MDR phenotype of the tumors was confirmed by Western blot.Results: The uptake kinetics of both complexes in human cancer cell lines is comparable with the one found for 99mTc-Sestamibi, increasing over time. The uptake of 99mTc-TMEOP is greatly reduced in cells overexpressing Pgp and increased in the presence of a Pgp modulator. In nude mice, the tumor uptake of 99mTc-TMEOP was higher in the MCF-7 xenografts compared with the MCF7 Pgp tumors.Conclusion: The uptake kinetics of both complexes in human cancer cell lines is comparable with the one found for 99mTc-Sestamibi, increasing over time. The uptake of 99mTc-TMEOP is greatly reduced in cells overexpressing Pgp, and increased in the presence of a Pgp modulator. In nude mice, the tumor uptake of 99mTc-TMEOP was higher in the MCF-7 xenografts compared with the MCF7 Pgp tumors