Influence of Several Compounds and Drugs on the Renal Uptake of Radiolabeled Affibody Molecules (original) (raw)
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Molecules, 2020
Albumin binding domain-Derived Affinity ProTeins (ADAPTs) are small (5 kDa) engineered scaffold proteins that are promising targeting agents for radionuclide-based imaging. A recent clinical study has demonstrated that radiolabeled ADAPTs can efficiently visualize human epidermal growth factor receptor 2 (HER2) expression in breast cancer using SPECT imaging. However, the use of ADAPTs directly labeled with radiometals for targeted radionuclide therapy is limited by their high reabsorption and prolonged retention of activity in kidneys. In this study, we investigated whether a co-injection of lysine or gelofusin, commonly used for reduction of renal uptake of radiolabeled peptides in clinics, would reduce the renal uptake of [99mTc]Tc(CO)3-ADAPT6 in NMRI mice. In order to better understand the mechanism behind the reabsorption of [99mTc]Tc(CO)3-ADAPT6, we included several compounds that act on various parts of the reabsorption system in kidneys. Administration of gelofusine, lysine,...
European Journal of Nuclear Medicine and Molecular Imaging, 2008
Purpose Affibody molecules are low molecular weight proteins (7 kDa), which can be selected to bind to tumour-associated target proteins with subnanomolar affinity. Because of rapid tumour localisation and clearance from nonspecific compartments, Affibody molecules are promising tracers for molecular imaging. Earlier, 99mTc-labelled Affibody molecules demonstrated specific targeting of tumour xenografts. However, the biodistribution was suboptimal either because of hepatobiliary excretion or high renal uptake of the radioactivity. The goal of this study was to optimise the biodistribution of Affibody molecules by chelator engineering. Materials and methods Anti-HER2 ZHER2:342 Affibody molecules, carrying the mercaptoacetyl-glutamyl-seryl-glutamyl (maESE), mercaptoacetyl-glutamyl-glutamyl-seryl (maEES) and mercaptoacetyl-seryl-glutamyl-glutamyl (maSEE) chelators, were prepared by peptide synthesis and labelled with 99mTc. The tumour-targeting capacity of these conjugates was compared with each other and with the best previously available conjugate, 99mTc-maEEE-ZHER2:342, in nude mice bearing SKOV-3 xenografts. The tumour-targeting capacity of the most promising conjugate, 99mTc-maESE-ZHER2:342, was compared with radioiodinated ZHER2:342. Results All novel conjugates demonstrated successful tumour targeting and a low degree of hepatobiliary excretion. The renal uptakes of serine-containing conjugates, 33 ± 5, 68 ± 21 and 71 ± 10%IA/g, for99mTc-maESE-ZHER2:342, 99mTc-maEES-ZHER2:342 and 99mTc-maSEE-ZHER2:342, respectively, were significantly reduced in comparison with 99mTc-maEEE-ZHER2:342 (102 ± 13%IA/g). For 99mTc-maESE-ZHER2:342, a tumour uptake of 9.6 ± 1.8%IA/g and a tumour-to-blood ratio of 58 ± 6 were reached at 4 h p.i. Conclusions A combination of serine and glutamic acid residues in the chelator sequence confers increased renal excretion and relatively low renal uptake of 99mTc-labelled Affibody molecules. In combination with preserved targeting capacity, this improved imaging of targets in abdominal area.
Amino Acids, 2012
Affibody molecules constitute a novel class of molecular display selected affinity proteins based on nonimmunoglobulin scaffold. Preclinical investigations and pilot clinical data have demonstrated that Affibody molecules provide high contrast imaging of tumor-associated molecular targets shortly after injection. The use of cysteine-containing peptide-based chelators at the C-terminus of recombinant Affibody molecules enabled site-specific labeling with the radionuclide 99m Tc. Earlier studies have demonstrated that position, composition and the order of amino acids in peptide-based chelators influence labeling stability, cellular processing and biodistribution of Affibody molecules. To investigate the influence of the amino acid order, a series of anti-HER2 Affibody molecules, containing GSGC, GEGC and GKGC chelators have been prepared and characterized. The affinity to HER2, cellular processing of 99m Tc-labeled Affibody molecules and their biodistribution were investigated. These properties were compared with that of the previously studied 99m Tc-labeled Affibody molecules containing GGSC, GGEC and GGKC chelators. All variants displayed picomolar affinities to HER2. The substitution of a single amino acid in the chelator had an appreciable influence on the cellular processing of 99m Tc. The biodistribution of all 99m Tc-labeled Affibody molecules was in general comparable, with the main difference in uptake and retention of radioactivity in excretory organs. The hepatic accumulation of radioactivity was higher for the lysine-containing chelators and the renal retention of 99m Tc was significantly affected by the amino acid composition of chelators. The order of amino acids influenced renal uptake of some conjugates at 1 h after injection, but the difference decreased at later time points. Such information can be helpful for the development of other scaffold protein-based imaging and therapeutic radiolabeled conjugates.
Drug Discovery Today, 2012
Radionuclide imaging of molecular targets for cancer therapy is likely to be a powerful tool for patient stratification and response monitoring, allowing more personalized cancer treatment. Radiolabeled proteins and peptides are a promising class of imaging probes for visualization of molecular targets in vivo. However, hepatic uptake and hepatobiliary excretion of radioactivity can decrease imaging contrast, reducing the detection sensitivity of hepatic and extrahepatic abdominal metastases, respectively. In this article, we review factors that influence the hepatic uptake of radioactivity (e.g. the chemical nature of radiocatabolites and physicochemical properties of targeting peptides and linkers) to provide input for the rational design of peptide-based imaging probes.
Indication for Different Mechanisms of Kidney Uptake of Radiolabeled Peptides
Journal of Nuclear Medicine, 2007
Nephrotoxicity due to renal reabsorption of radiolabeled peptides limits the tumor dose in peptide receptor radiotherapy (PRRT). Therefore, we evaluated the ability of several agents to inhibit the renal accumulation of different radiopeptides. Methods: Male Wistar rats (4 per group) were injected intravenously with 1 MBq of 111 In-labeled octreotide (OCT), minigastrin (MG), bombesin (BOM), or exendin (EX), together with a potential inhibitor of renal uptake (lysine [Lys], poly-glutamic acid [PGA], and Gelofusine [GF], a gelatin-based plasma expander) or phosphatebuffered saline as a control. Organ uptake at 20 h after injection was determined as the percentage of injected activity per gram (%IA/g). Lys, PGA, and GF were also combined to determine whether an additive effect could be obtained. The localization of the peptides in the kidneys was investigated by autoradiography using a phosphor imager. Results: OCT accumulation in the kidney was inhibited by Lys and GF (40.7%-45.1%), whereas PGA was ineffective. On the other hand, renal uptake of BOM, MG, and EX was inhibited by PGA and GF (15.4%-85.4%), whereas Lys was ineffective. The combination of GF and Lys showed additive effects in inhibiting OCT uptake, whereas PGA and GF had additive effects for the inhibition of EX uptake. The amount of kidney uptake correlated with the number of charged amino acids. All radiopeptides were localized in the renal cortex, as indicated by autoradiography. Conclusion: Inhibition of renal accumulation of the radiopeptides tested could be achieved by either Lys or PGA but not by both at the same time, suggesting 2 different uptake mechanisms. The differences in renal accumulation of radiopeptides may be related to the number of charges of a molecule. GF is the only compound that inhibited renal accumulation of all radiopeptides tested. Additional experiments are needed to further elucidate these findings and to optimize inhibition of renal accumulation of radiopeptides to reduce the kidney dose in PRRT.
European journal of medicinal chemistry, 2014
Affibody molecules constitute a class of small (7 kDa) scaffold proteins that can be engineered to have excellent tumor targeting properties. High reabsorption in kidneys complicates development of affibody molecules for radionuclide therapy. In this study, we evaluated the influence of the composition of cysteine-containing C-terminal peptide-based chelators on the biodistribution and renal retention of (188)Re-labeled anti-HER2 affibody molecules. Biodistribution of affibody molecules containing GGXC or GXGC peptide chelators (where X is G, S, E or K) was compared with biodistribution of a parental affibody molecule ZHER2:2395 having a KVDC peptide chelator. All constructs retained low picomolar affinity to HER2-expressing cells after labeling. The biodistribution of all (188)Re-labeled affibody molecules was in general comparable, with the main observed difference found in the uptake and retention of radioactivity in excretory organs. The (188)Re-ZHER2:V2 affibody molecule with a...
Molecular Medicine Reports, 2023
The feasibility of targeted imaging and therapy using radiolabeled albumin-binding domain-derived affinity proteins (adaPTs) has been demonstrated. However, high renal uptake of radioactivity limits the maximum tolerated dose. Successful reduction of renal retention of radiolabeled Fab fragments has been demonstrated by incorporating a cleavable linker between the targeting agent and the radiometal chelator. The present study investigated if the introduction of a glycine-leucine-glycine-lysine (GlGK)-linker would reduce the kidney uptake of radiolabeled adaPT6 and also compared it with the non-residualizing [ 125 i]i-[(4-hydroxyphenyl)ethyl] maleimide ([ 125 i]i-HPeM) labeling strategy. GlGK was site-specifically coupled to human epidermal growth factor receptor 2 (Her2)-targeting adaPT6. conjugates without the cleavable linker were used as controls and all constructs were labeled with lutetium-177 (177 lu). [ 125 i]i-HPeM was coupled to adaPT6 at the c-terminus. Biodistribution of all constructs was evaluated in nMri mice 4 h after injection. Specific binding to HER2-expressing cells in vitro was demonstrated for all constructs. No significant difference in kidney uptake was observed between the [ 177 lu] lu-2,2' ,2",2"'-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl) tetraacetic acid-GlGK-conjugates and the controls. The renal activity of [ 125 i]i-HPeM-adaPT6 was significantly lower compared with all other constructs. in conclusion, the incorporation of the cleavable GlGK-linker did not result in lower renal retention. Therefore, the present study emphasized that, in order to achieve a reduction of renal retention, alternative molecular design strategies may be required for different targeting agents.
High-performance renal imaging with a radiolabeled, non-excretable chimeric fusion protein
Theranostics, 2021
Ideal nuclear imaging tracers should exhibit high target uptake and low background signal. Traditional renal scintigraphy and SPECT scans examine kidney function via static or dynamic tracing of radioactive probes in the kidneys. The lack of tracer affinity to specific biological processes and high background uptake from urinary excretion have added many difficulties to precision renal diagnosis. In this issue of Theranostics, Jin and colleagues innovatively devised a recombinant probe for preferential kidney imaging through targeting of tubular neonatal Fc receptor and proximal tubular basement membrane for sustained tubular reabsorption and accumulation. This work has broad implications regarding how an in depth understanding of physiology and pathology may be of service for tracer development, renal diagnosis, and disease theranostics.
Feasibility of Affibody Molecule-Based PNA-Mediated Radionuclide Pretargeting of Malignant Tumors
Theranostics, 2016
Affibody molecules are small (7 kDa), non-immunoglobulin scaffold proteins with a potential as targeting agents for radionuclide imaging of cancer. However, high renal re-absorption of Affibody molecules prevents their use for radionuclide therapy with residualizing radiometals. We hypothesized that the use of Affibody-based peptide nucleic acid (PNA)-mediated pretargeting would enable higher accumulation of radiometals in tumors than in kidneys. To test this hypothesis, we designed an Affibody-PNA chimera Z HER2:342-SR-HP1 containing a 15-mer HP1 PNA recognition tag and a complementary HP2 hybridization probe permitting labeling with both 125 I and 111 In. 111 In-Z HER2:342-SR-HP1 bound specifically to HER2-expressing BT474 and SKOV-3 cancer cells in vitro, with a K D of 6±2 pM for binding to SKOV-3 cells. Specific high affinity binding of the radiolabeled complementary PNA probe 111 In-/ 125 I-HP2 to Z HER2:342-SR-HP1 pre-treated cells was demonstrated. 111 In-Z HER2:342-SR-HP1 demonstrated specific accumulation in SKOV-3 xenografts in BALB/C nu/nu mice and rapid clearance from blood. Pre-saturation of SKOV-3 with non-labeled anti-HER2 Affibody or the use of HER2-negative Ramos xenografts resulted in significantly lower tumor uptake of 111 In-Z HER2:342-SR-HP1. The complementary PNA probe 111 In/ 125 I-HP2 accumulated in SKOV-3 xenografts when Z HER2:342-SR-HP1 was injected 4 h earlier. The tumor accumulation of 111 In/ 125 I-HP2 was negligible without Z HER2:342-SR-HP1 pre-injection. The uptake of 111 In-HP2 in SKOV-3 xenografts was 19±2 %ID/g at 1 h after injection. The uptake in blood and kidneys was approximately 50-and 2-fold lower, respectively. In conclusion, we have shown that the use of Affibody-based PNA-mediated pretargeting enables specific delivery of radiometals to tumors and provides higher radiometal concentration in tumors than in kidneys.