scholarly journals H-CRRETAWAC-OH, a Lead Structure for the Development of Radiotracer Targeting Integrinα5β1?

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Roland Haubner ◽  
Simone Maschauer ◽  
Jürgen Einsiedel ◽  
Iris E. Eder ◽  
Christine Rangger ◽  
...  

Imaging of angiogenic processes is of great interest in preclinical research as well as in clinical settings. The most commonly addressed target structure for imaging angiogenesis is the integrinαvβ3. Here we describe the synthesis and evaluation of [18F]FProp-Cys*-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys*-OH, a radiolabelled peptide designed to selectively target the integrinα5β1. Conjugation of 4-nitrophenyl-(RS)-2-[18F]fluoropropionate provided [18F]FProp-Cys*-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys*-OH in high radiochemical purity (>95%) and a radiochemical yield of approx. 55%. In vitro evaluation showedα5β1binding affinity in the nanomolar range, whereas affinity toαvβ3andαIIbβ3was >50 μM. Cell uptake studies using human melanoma M21 (αvβ3-positive andα5β1-negative), human melanoma M21-L (αvβ3-negative andα5β1-negative), and human prostate carcinoma DU145 (αvβ3-negative andα5β1-positive) confirmed receptor-specific binding. The radiotracer was stable in human serum and showed low protein binding. Biodistribution studies showed tumour uptake ranging from 2.5 to 3.5% ID/g between 30 and 120 min post-injection. However, blocking studies and studies using mice bearingα5β1-negative M21 tumours did not confirm receptor-specific uptake of [18F]FProp-Cys*-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys*-OH, although this radiopeptide revealed high affinity and substantial selectivity toα5β1in vitro. Further experiments are needed to study the in vivo metabolism of this peptide and to develop improved radiopeptide candidates suitable for PET imaging ofα5β1expression in vivo.

2003 ◽  
Vol 42 (04) ◽  
pp. 173-180 ◽  
Author(s):  
M. P. Law ◽  
K. Kopka ◽  
St. Wagner ◽  
S. Luthra ◽  
V. W. Pike ◽  
...  

Summary: Aim: As results of cardiac biopsies suggest, myocardial β1-adrenoceptor density is reduced in patients with chronic heart failure. However, changes in cardiac β2-adrenoceptors vary. With suitable radiopharmaceuticals single photon emission computed tomography (SPECT) and positron emission tomography (PET) offer the opportunity to assess β-adrenoceptors non-invasively. Among the novel racemic analogues of the established β1-selective adrenoceptor antagonist ICI 89.406 the iodinated 2-I-ICI-H showed high affinity and selectivity to β1-adrenoceptors in murine ventricular membranes. The aim of this study was its evaluation as a putative sub-type selective β1-adrenergic radioligand in cardiac imaging. Methods: Competition studies in vitro and in vivo were used to investigate the kinetics of 2-I-ICI-H binding to cardiac β-adrenoceptors in mice and rats. In addition, the radiosynthesis of 2-125I-ICI-H from the silylated precursor 2-SiMe3-ICI-H was established. The specific activity was 80 GBq/µmol, the radiochemical yield ranged from 70 to 80%. Results: The unlabelled compound 2-I-ICI-H showed high β1-selectivity and -affinity in the in vitro competition studies. In vivo biodistribution studies apparently showed low affinity to cardiac β-adrenoceptors. The radiolabelled counterpart 2-125I-ICI-H showed a high degree of non-specific binding in vitro and no specific binding to cardiac β1-adrenoceptors in vivo. Conclusion: Because of its high non-specific binding 2-125I-ICI-H is no suitable radiotracer for imaging in vivo.


2019 ◽  
Vol 18 (9) ◽  
pp. 1289-1294 ◽  
Author(s):  
Kusum Vats ◽  
Rohit Sharma ◽  
Haladhar D. Sarma ◽  
Drishty Satpati ◽  
Ashutosh Dash

Aims: The urokinase Plasminogen Activator Receptors (uPAR) over-expressed on tumor cells and their invasive microenvironment are clinically significant molecular targets for cancer research. uPARexpressing cancerous lesions can be suitably identified and their progression can be monitored with radiolabeled uPAR targeted imaging probes. Hence this study aimed at preparing and evaluating two 68Ga-labeled AE105 peptide conjugates, 68Ga-NODAGA-AE105 and 68Ga-HBED-CC-AE105 as uPAR PET-probes. Method: The peptide conjugates, HBED-CC-AE105-NH2 and NODAGA-AE105-NH2 were manually synthesized by standard Fmoc solid phase strategy and subsequently radiolabeled with 68Ga eluted from a commercial 68Ge/68Ga generator. In vitro cell studies for the two radiotracers were performed with uPAR positive U87MG cells. Biodistribution studies were carried out in mouse xenografts with the subcutaneously induced U87MG tumor. Results: The two radiotracers, 68Ga-NODAGA-AE105 and 68Ga-HBED-CC-AE105 that were prepared in >95% radiochemical yield and >96% radiochemical purity, exhibited excellent in vitro stability. In vivo evaluation studies revealed higher uptake of 68Ga-HBED-CC-AE105 in U87MG tumor as compared to 68Ga-NODAGAAE105; however, increased lipophilicity of 68Ga-HBED-CC-AE105 resulted in slower clearance from blood and other non-target organs. The uPAR specificity of the two radiotracers was ascertained by significant (p<0.05) reduction in the tumor uptake with a co-injected blocking dose of unlabeled AE-105 peptide. Conclusion: Amongst the two radiotracers studied, the neutral 68Ga-NODAGA-AE105 with more hydrophilic chelator exhibited faster clearance from non-target organs. The conjugation of HBED-CC chelator (less hydrophilic) resulted in negatively charged 68Ga-HBED-CC-AE105 which was observed to have high retention in blood that decreased target to non-target ratios.


Author(s):  
Thu Hang Lai ◽  
Magali Toussaint ◽  
Rodrigo Teodoro ◽  
Sladjana Dukić-Stefanović ◽  
Daniel Gündel ◽  
...  

Abstract Purpose The adenosine A2A receptor has emerged as a therapeutic target for multiple diseases, and thus the non-invasive imaging of the expression or occupancy of the A2A receptor has potential to contribute to diagnosis and drug development. We aimed at the development of a metabolically stable A2A receptor radiotracer and report herein the preclinical evaluation of [18F]FLUDA, a deuterated isotopologue of [18F]FESCH. Methods [18F]FLUDA was synthesized by a two-step one-pot approach and evaluated in vitro by autoradiographic studies as well as in vivo by metabolism and dynamic PET/MRI studies in mice and piglets under baseline and blocking conditions. A single-dose toxicity study was performed in rats. Results [18F]FLUDA was obtained with a radiochemical yield of 19% and molar activities of 72–180 GBq/μmol. Autoradiography proved A2A receptor–specific accumulation of [18F]FLUDA in the striatum of a mouse and pig brain. In vivo evaluation in mice revealed improved stability of [18F]FLUDA compared to that of [18F]FESCH, resulting in the absence of brain-penetrant radiometabolites. Furthermore, the radiometabolites detected in piglets are expected to have a low tendency for brain penetration. PET/MRI studies confirmed high specific binding of [18F]FLUDA towards striatal A2A receptor with a maximum specific-to-non-specific binding ratio in mice of 8.3. The toxicity study revealed no adverse effects of FLUDA up to 30 μg/kg, ~ 4000-fold the dose applied in human PET studies using [18F]FLUDA. Conclusions The new radiotracer [18F]FLUDA is suitable to detect the availability of the A2A receptor in the brain with high target specificity. It is regarded ready for human application.


2019 ◽  
Vol 20 (3) ◽  
pp. 471 ◽  
Author(s):  
Shriya S. Srinivasan ◽  
Rajesh Seenivasan ◽  
Allison Condie ◽  
Stanton L. Gerson ◽  
Yanming Wang ◽  
...  

Chemotherapeutic dosing, is largely based on the tolerance levels of toxicity today. Molecular imaging strategies can be leveraged to quantify DNA cytotoxicity and thereby serve as a theranostic tool to improve the efficacy of treatments. Methoxyamine-modified cyanine-7 (Cy7MX) is a molecular probe which binds to apurinic/apyrimidinic (AP)-sites, inhibiting DNA-repair mechanisms implicated by cytotoxic chemotherapies. Herein, we loaded (Cy7MX) onto polyethylene glycol-coated gold nanoparticles (AuNP) to selectively and stably deliver the molecular probe intravenously to tumors. We optimized the properties of Cy7MX-loaded AuNPs using optical spectroscopy and tested the delivery mechanism and binding affinity using the DLD1 colon cancer cell line in vitro. A 10:1 ratio of Cy7MX-AuNPs demonstrated a strong AP site-specific binding and the cumulative release profile demonstrated 97% release within 12 min from a polar to a nonpolar environment. We further demonstrated targeted delivery using imaging and biodistribution studies in vivo in an xenografted mouse model. This work lays a foundation for the development of real-time molecular imaging techniques that are poised to yield quantitative measures of the efficacy and temporal profile of cytotoxic chemotherapies.


Cancers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1168
Author(s):  
Haozhong Ding ◽  
Mohamed Altai ◽  
Sara S. Rinne ◽  
Anzhelika Vorobyeva ◽  
Vladimir Tolmachev ◽  
...  

Affibody molecules are small affinity-engineered scaffold proteins which can be engineered to bind to desired targets. The therapeutic potential of using an affibody molecule targeting HER2, fused to an albumin-binding domain (ABD) and conjugated with the cytotoxic maytansine derivate MC-DM1 (AffiDC), has been validated. Biodistribution studies in mice revealed an elevated hepatic uptake of the AffiDC, but histopathological examination of livers showed no major signs of toxicity. However, previous clinical experience with antibody drug conjugates have revealed a moderate- to high-grade hepatotoxicity in treated patients, which merits efforts to also minimize hepatic uptake of the AffiDCs. In this study, the aim was to reduce the hepatic uptake of AffiDCs and optimize their in vivo targeting properties. We have investigated if incorporation of hydrophilic glutamate-based spacers adjacent to MC-DM1 in the AffiDC, (ZHER2:2891)2–ABD–MC-DM1, would counteract the hydrophobic nature of MC-DM1 and, hence, reduce hepatic uptake. Two new AffiDCs including either a triglutamate–spacer–, (ZHER2:2891)2–ABD–E3–MC-DM1, or a hexaglutamate–spacer–, (ZHER2:2891)2–ABD–E6–MC-DM1 next to the site of MC-DM1 conjugation were designed. We radiolabeled the hydrophilized AffiDCs and compared them, both in vitro and in vivo, with the previously investigated (ZHER2:2891)2–ABD–MC-DM1 drug conjugate containing no glutamate spacer. All three AffiDCs demonstrated specific binding to HER2 and comparable in vitro cytotoxicity. A comparative biodistribution study of the three radiolabeled AffiDCs showed that the addition of glutamates reduced drug accumulation in the liver while preserving the tumor uptake. These results confirmed the relation between DM1 hydrophobicity and liver accumulation. We believe that the drug development approach described here may also be useful for other affinity protein-based drug conjugates to further improve their in vivo properties and facilitate their clinical translatability.


2020 ◽  
Vol 21 (18) ◽  
pp. 6597
Author(s):  
Chao-Cheng Chen ◽  
Yang-Yi Chen ◽  
Yi-Hsuan Lo ◽  
Ming-Hsien Lin ◽  
Chih-Hsien Chang ◽  
...  

Malignant melanoma is the most harmful type of skin cancer and its incidence has increased in this past decade. Early diagnosis and treatment are urgently desired. In this study, we conjugated picolinamide/nicotinamide with the pharmacophore of 131I-MIP-1145 to develop 131I-iodofluoropicolinamide benzamide (131I-IFPABZA) and 131I-iodofluoronicotiamide benzamide (131I-IFNABZA) with acceptable radiochemical yield (40 ± 5%) and high radiochemical purity (>98%). We also presented their biological characteristics in melanoma-bearing mouse models. 131I-IFPABZA (Log P = 2.01) was more lipophilic than 131I-IFNABZA (Log P = 1.49). B16F10-bearing mice injected with 131I-IFNABZA exhibited higher tumor-to-muscle ratio (T/M) than those administered with 131I-IFPABZA in planar γ-imaging and biodistribution studies. However, the imaging of 131I-IFNABZA- and 131I-IFPABZA-injected mice only showed marginal tumor uptake in A375 amelanotic melanoma-bearing mice throughout the experiment period, indicating the high binding affinity of these two radiotracers to melanin. Comparing the radiation-absorbed dose of 131I-IFNABZA with the melanin-targeted agents reported in the literature, 131I-IFNABZA exerts lower doses to normal tissues on the basis of similar tumor dose. Based on the in vitro and in vivo studies, we clearly demonstrated the potential of using 131I-IFNABZA as a theranostic agent against melanoma.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mahmoud H. Sanad ◽  
Safaa B. Challan ◽  
Fawzy A. Marzook ◽  
Sayed M. Abd-Elhaliem ◽  
Ebtisam A. Marzook

AbstractOne of the most famous techniques for stomach ulcer imaging is the nuclear imaging technique. We aim to focus on the synthesis of 125I-cimetidine (125I-cim) as an agent for peptic ulcer imaging. Cimetidine was labeled with Iodine-125 using a different oxidizing agent (Ch-T, NBS). All factors affecting the labeling yield were optimized. The radiochemical yield of 125I-cim was 98 ± 0.22% at optimum conditions. In vitro stability, in vivo biodistribution of 125I-cimetidine was studied in three groups: control group, pretreated group, and ulcer bearing group. In vivo biodistribution studies of 125I-cim revealed high uptake in the stomach ulcer, reaching about 75.4 ± 1.2% ID/g at 15 min post-injection, than pretreated groups compared to the control. The results showed the suitability of using 125I-cimetidine for stomach ulcer imaging.


2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Dominik Summer ◽  
Christine Rangger ◽  
Maximilian Klingler ◽  
Peter Laverman ◽  
Gerben M. Franssen ◽  
...  

Cholecystokinin-2 receptors (CCK2R) are overexpressed in a variety of malignant diseases and therefore have gained certain attention for peptide receptor radionuclide imaging. Among extensive approaches to improve pharmacokinetics and metabolic stability of minigastrin (MG) based radioligands, the concept of multivalency for enhanced tumour targeting has not been investigated extensively. We therefore utilized fusarinine C (FSC) as chelating scaffold for novel mono-, di-, and trimeric bioconjugates for targeting CCK2R expression. FSC-based imaging probes were radiolabelled with positron emitting radionuclides (gallium-68 and zirconium-89) and characterized in vitro (log⁡D, IC50, and cell uptake) and in vivo (metabolic stability in BALB/c mice, biodistribution profile, and microPET/CT imaging in A431-CCK2R/A431-mock tumour xenografted BALB/c nude mice). Improved targeting did not fully correlate with the grade of multimerization. The divalent probe showed higher receptor affinity and increased CCK2R mediated cell uptake while the trimer remained comparable to the monomer. In vivo biodistribution studies 1 h after administration of the 68Ga-labelled radioligands confirmed this trend, but imaging at late time point (24 h) with 89Zr-labelled counterparts showed a clearly enhanced imaging contrast of the trimeric probe compared to the mono- and dimer. Furthermore, in vivo stability studies showed a higher metabolic stability for multimeric probes compared to the monomeric bioconjugate. In summary, we could show that FSC can be utilized as suitable scaffold for novel mono- and multivalent imaging probes for CCK2R-related malignancies with partly improved targeting properties for multivalent conjugates. The increased tumour accumulation of the trimer 24 h postinjection (p.i.) can be explained by slower clearance and increased metabolic stability of multimeric conjugates.


2020 ◽  
Author(s):  
Zhen-Feng Liu ◽  
Jun Yang ◽  
Qianni Ye ◽  
Min Yang ◽  
Dong-hui Pan ◽  
...  

Abstract Background: MALAT-1 (Metastasis-Associated Lung Adenocarcinoma Transcript 1) is a large long nuclear noncoding RNA (lncRNA) that is overexpressed in an array of cancers. In this study, we designed a range of positron probes for MALAT-1 to evaluate its distribution, pharmacokinetics, and to explore whether the probe can be used for the imaging of malignant tumors with high MALAT-1 expression in vivo. Methods: 68Ga labelling of MALAT-1 antisense oligonucleotides (68Ga–MALAT-1 ASO) was synthesized by the conjugation of MALAT-1 NOTA-ASO and 68Ga3+. Purity was assessed by radio-HPLC. Pharmacokinetic studies and cell uptake were assessed. The biodistribution and metabolism of 68Ga–MALAT-1 ASO in normal ICR and MHCC-LM3 xenograft-bearing nude mice were studied. Results: 68Ga–MALAT-1 ASO was obtained at a radiochemical yield of 98% from a 10 min synthesis with 100 ± 50 MBq/nmol activity and > 99% purity once synthesized. The Log P was -2.53±0.19. The tracer displayed excellent stability in vitro. 68Ga–MALAT-1 ASO showed satisfactory binding ability to MHCC-LM3 cells; the biodistribution of 68Ga-MALAT-1 ASO in MHCC-LM3 tumour-bearing mice showed high levels of uptake (3.04 ± 0.11%ID/g). Micro-PET scans demonstrated the tumor specific uptake of 68Ga-MALAT-1 ASO in mouse models. Conclusions: We conclude that 68Ga labelling of MALAT-1 ASO is a convenient approach to label tumors overexpressing MALAT-1.


Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2527-2527 ◽  
Author(s):  
Aaron Chang ◽  
Tao Dao ◽  
Andrew Scott ◽  
Leonid Dubrovsky ◽  
Cheng Liu ◽  
...  

Abstract Preferentially expressed antigen in melanoma (PRAME) is a well-validated target for T cell-based immunotherapy in leukemias and solid tumors. PRAME is a retinoic acid receptor binding protein that prevents retinoic acid-mediated differentiation, proliferation arrest, and apoptosis. As a cancer-testis antigen, PRAME has limited expression in healthy adult tissue that is restricted to the testes, ovaries, and endometrium. However, PRAME is over-expressed in multiple cancers including ALL, AML, melanomas, and breast cancers, making it a specific and highly attractive therapeutic target. PRAME is an intracellular protein making it impossible to target using traditional antibodies and it is not currently druggable. After proteasomal processing, the PRAME300-309 peptide is presented on the cell surface in the context of HLA*A02:01 molecules, for recognition by CD8 T cells. We therefore hypothesized that a TCR-mimic (TCRm) monoclonal antibody that recognizes surface PRAME300-309 presented by HLA*A02:01 could have therapeutic activity. Here, we describe Pr20, a therapeutic TCRm antibody, specific for the PRAME300-309 peptide in complex with HLA*A02:01, identified through a human scFv phage display library screen. Pr20 was engineered into full length human IgG1. Pr20 exhibited specific binding to PRAME300-309 -pulsed TAP-deficient T2 cells and bound PRAME+/ HLA*A02:01+ Ph+ ALL and AML, demonstrating that endogenously presented PRAME300-309 could be recognized by Pr20. Pr20 was determined to have 4 nM binding affinity by scatchard plot analysis. The specific epitope was mapped using alanine substitutions of non-anchor residues in the PRAME300-309 peptide and determined to primarily require the C-terminal residues. Pr20M, an afucosylated form of the antibody with enhanced Fc binding, mediated antibody-dependent cellular cytotoxicity (ADCC) in-vitro in a PRAME+/ HLA*A02:01+ restricted manner. Pharmacokinetic studies in C57BL/6 mice indicated that Pr20M was stable in-vivo and biodistribution studies in HLA*A02:01 transgenic mice suggested that there was no significant antibody sink. Pr20M was therapeutically active in established xenograft leukemia models in NSG mice (T, B, and NK-deficient). Interestingly, Pr20 binding to PRAME+/HLA*A02:01+ melanomas was minimally detectable, but was dramatically increased upon treatment with IFNγ, which also led to an increased sensitivity to ADCC. The data provide rationale for developing TCRm antibodies against intracellular oncoproteins as therapeutics. Disclosures No relevant conflicts of interest to declare.


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