Radiolabeling efficiency and stability study on Lutetium-177 labeled bombesin peptide (original) (raw)
Related papers
Cancer Research, 2004
Bombesin receptors are overexpressed on a variety of human tumors like prostate, breast, and lung cancer. The aim of this study was to develop radiolabeled (Indium-111, Lutetium-177, and Yttrium-90) bombesin analogues with affinity to the three bombesin receptor subtypes for targeted radiotherapy. The following structures were synthesized: diethylenetriaminepentaacetic acid-␥-aminobutyric acid-[D-Tyr 6 , -Ala 11 , Thi 13 , Nle 14 ] bombesin (6 -14) (BZH1) and 1,4,7,10-tetraazacyclododecane-N,N,N؆,Nٟ -tetraacetic acid-␥-aminobutyric acid-[D-Tyr 6 , -Ala 11 , Thi 13 , Nle 14 ] bombesin (6 -14) (BZH2). [ 111 In]-BZH1 and in particular [ 90 Y]-BZH2 were shown to have high affinity to all three human bombesin receptor subtypes with binding affinities in the nanomolar range. In human serum metabolic cleavage was found between -Ala 11 and His 12 with an approximate half-life of 2 hours. The metabolic breakdown was inhibited by EDTA and -Ala 11 -His 12 (carnosine) indicating that carnosinase is the active enzyme.
Radiopharmaceutical development of radiolabelled peptides
European Journal of Nuclear Medicine and Molecular Imaging, 2012
Receptor targeting with radiolabelled peptides has become very important in nuclear medicine and oncology in the past few years. The overexpression of many peptide receptors in numerous cancers, compared to their relatively low density in physiological organs, represents the molecular basis for in vivo imaging and targeted radionuclide therapy with radiolabelled peptide-based probes. The prototypes are analogs of somatostatin which are routinely used in the clinic. More recent developments include somatostatin analogs with a broader receptor subtype profile or with antagonistic properties. Many other peptide families such as bombesin, cholecystokinin/gastrin, glucagon-like peptide-1 (GLP-1)/exendin, arginine-glycine-aspartic acid (RGD) etc. have been explored during the last few years and quite a number of potential radiolabelled probes have been derived from them. On the other hand, a variety of strategies and optimized protocols for efficient labelling of peptides with clinically relevant radionuclides such as 99m Tc, M 3+ radiometals (111 In, 86/90 Y, 177 Lu, 67/68 Ga), 64/67 Cu, 18 F or radioisotopes of iodine have been developed. The labelling approaches include direct labelling, the use of bifunctional chelators or prosthetic groups. The choice of the labelling approach is driven by the nature and the chemical properties of the radionuclide. Additionally, chemical strategies, including modification of the amino acid sequence and introduction of linkers/spacers with different characteristics, have been explored for the improvement of the overall performance of the radiopeptides, e.g. metabolic stability and pharmacokinetics. Herein, we discuss the development of peptides as radiopharmaceuticals starting from the choice of the labelling method and the conditions to the design and optimization of the peptide probe, as well as some recent developments, focusing on a selected list of peptide families, including somatostatin, bombesin, cholecystokinin/gastrin, GLP-1/exendin and RGD.
European journal of …, 2007
Purpose We aimed at designing and developing a novel bombesin analogue, DOTA-PEG4-BN(7-14) (DOTA-PESIN), with the goal of labelling it with 67/68 Ga and 177 Lu for diagnosis and radionuclide therapy of prostate and other human cancers overexpressing bombesin receptors. Methods The 8-amino acid peptide bombesin (7-14) was coupled to the macrocyclic chelator DOTA via the spacer 15-amino-4,7,10,13-tetraoxapentadecanoic acid (PEG 4). The conjugate was complexed with Ga(III) and Lu(III) salts. The GRP receptor affinity and the bombesin receptor subtype profile were determined in human tumour specimens expressing the three bombesin receptor subtypes. Internalisation and efflux studies were performed with the human GRP receptor cell line PC-3. Xenografted nude mice were used for biodistribution. Results [Ga III /Lu III ]-DOTA-PESIN showed good affinity to GRP and neuromedin B receptors but no affinity to BB3. [ 67 Ga/ 177 Lu]-DOTA-PESIN internalised rapidly into PC-3 cells whereas the efflux from PC-3 cells was relatively slow. In vivo experiments showed a high and specific tumour uptake and good retention of [ 67 Ga/ 177 Lu]-DOTA-PESIN. [ 67 Ga/ 177 Lu]-DOTA-PESIN highly accumulated in GRP receptor-expressing mouse pancreas. The uptake specificity was demonstrated by blocking tumour uptake and pancreas uptake. Fast clearance was found from blood and all non-target organs except the kidneys. High tumourto-normal tissue ratios were achieved, which increased with time. PET imaging with [ 68 Ga]-DOTA-PESIN was successful in visualising the tumour at 1 h post injection. Planar scintigraphic imaging showed that the 177 Lu-labelled peptide remained in the tumour even 3 days post injection. Conclusion The newly designed ligands have high potential with regard to PET and SPECT imaging with 68/67 Ga and targeted radionuclide therapy with 177 Lu.
Peptide-based Radiopharmaceuticals at a Glance
Tabari Biomedical Student Research Journal, 2021
Because of peptide receptors overexpression in many of the human tumors, the peptide receptors would be an attractive target for diagnostic imaging and radiotherapy. Accordingly, peptide-based radiopharmaceuticals were designed to bind to these receptors and be able to pursue their goals. Wide range of bifunctional chelating agents (BFCA) can be used for the convenient radiolabeling of bioactive peptides with different radionuclides. These advantages have led to producing a wide variety of peptide radiopharmaceuticals. A number of these peptides, such as bombesin, somatostatin, neurotensin, cholecystokinin/gastrin and vasoactive intestinal peptide have been able to have clinical applications in nuclear oncology. In this article we have tried to have an overview of peptide-based radiopharmaceuticals.
Nuclear Medicine and Biology, 2009
Introduction: The aim of the study was to compare in vitro and in vivo a novel DOTA-chelated bombesin (BN) analog of the amino acid sequence, QRLGNQWAVGHLM-CONH 2 (BN NH 2 ), labeled with 90 Y and 177 Lu, for its potential use in targeted radiotherapy of tumors expressing gastrin releasing peptide (GRP) receptors. The same amino acid sequence, but with different chelator, referred as BN1.1 (Gly-Gly-Cys-Aca-QRLGNQWAVGHLM-CONH 2 ), has already been studied and reported; however, the DOTA-chelated one, suitable for labeling with M +3 type radiometals, was not yet described. Methods: The conditions for labeling of DOTA-BN[2-14]NH 2 with noncarrier added 90 Y and with 177 Lu [specific activity (SA), 15 Ci/mg Lu] were investigated and optimized to provide 90 Y-DOTA-BN[2-14]NH 2 and 177 Lu-DOTA-BN[2-14]NH 2 of high SA. The stability of the radiolabeled compounds in human serum was evaluated over a period of 24 h. The human prostate cancer cell line PC-3, known to express GRP receptors, was used for in vitro evaluation of radiolabeled peptide affinity to GRP receptors and for assessment of cytotoxicity of both nonlabeled and radiolabeled peptide. Biodistribution accompanied by receptor blocking was studied in normal Swiss mice. Results: 90 Y-DOTA-BN[2-14]NH 2 and 177 Lu-DOTA-BN[2-14]NH 2 were obtained with radiochemical yield N98% and high SA (67.3 GBq 90 Y/μmol and 33.6 GBq 177 Lu/μmol, respectively). They were stable when incubated in human serum for up to 24 h. The binding affinities of DOTA-BN[2-14]NH 2 and both nat Y-and nat Lu-labeled analogs to GRP receptors were high (IC 50 =1.78, 1.99, and 1.34 nM, respectively), especially for the nat Lu-DOTA-BN[2-14]NH 2 complex. The cytotoxicity study of DOTA-BN[2-14]NH 2 to PC-3 cells revealed an IC 50 =6300 nM after 72 h of exposition, while the labeled derivatives showed no significant cytotoxic effect. The internalization rate to PC-3 cells was more rapid for 177 Lu-labeled peptide (84.87%) than for the 90 Y-labeled one (80.79%), while the efflux rate was slower for 177 Lu-DOTA-BN[2-14]NH 2 (46.8% vs. 61.74%). The biodistribution study of both derivatives in normal mice revealed a specific binding to GRP receptor-positive tissues, which could be blocked by coinjection of cold peptide. The effect of receptor blockage in vivo was also more pronounced for the 177 Lu-labeled peptide than that for the 90 Y-labeled (81% vs. 42%, respectively). Conclusions: Our studies demonstrated that DOTA-BN[2-14]NH 2 can be labeled with 90 Y (NCA) and 177 Lu (CA) with high radiochemical yields. The in vitro and in vivo comparison between 90 Y-DOTA-BN[2-14]NH 2 and 177 Lu-DOTA-BN[2-14]NH 2 indicated that the change of radiometal in the complex from Y to Lu influence the binding affinity to the GRP receptors with preference to the 177 Lu-labeled derivative.
Applied Radiation and Isotopes, 2008
A robust formulation was developed for [ 177 Lu]Lu-AMBA (177 Lu-DO3A-CH 2 COG -[4-aminobenzoyl]-QWAVGHLM-NH 2), a Bombesin-like agonist with high affinity for Gastrin Releasing Peptide (GRP) receptors. During optimization of labeling, the effect of several radiostabilizers was evaluated; a combination of selenomethionine and ascorbic acid showed superiority over other tested radiostabilizers. The resulting two-vial formulation maintains a radiochemical purity (RCP) of 490% for at least 2 days at room temperature. The method of stabilization should be useful for other methionine-containing peptide radiopharmaceuticals in diagnostic and therapeutic applications.
Evaluation of radiolabelled bombesin analogues for receptor-targeted scintigraphy and radiotherapy
International Journal of Cancer, 1999
The 14-aminoacid peptide bombesin (BN) has a high affinity for the gastrin-releasing peptide receptor which is expressed by a variety of tumours. Thus, radiometal-labelled DTPA-BN derivatives are potentially useful radioligands for receptor-targeted scintigraphy and radiotherapy of BN receptor-expressing tumours. A number of such DTPA-BN analogues, [DTPA-D-Tyr 6 ]BN(6-13)NHEt (Et؍ethyl), [DTPA-Tyr 5 ,D-Phe 6 ]BN(5-13)NHEt, [DTPA-D-Phe 6 ,Leu 13 ⌿Phe 14 ]-BN(6-14), [DTPA-Tyr 5 ,D-Phe 6 ,Leu 13 ⌿Phe 14 ]BN(5-14), [DTPA-Pro 1 ,Tyr 4 ]BN and [DTPA-Pro 1 ,Tyr 4 ,Nle 14 ]BN, were synthesized and studied for their binding characteristics to the BN receptor on 7315b rat pituitary tumour cell membranes in competition with [ 125 I-Tyr 4 ]BN. The effects of the BN analogues were determined on basal and BN-stimulated prolactin secretion by 7315b cells to distinguish between their agonistic and antagonistic characterisitics. Internalization of selected 111 In-labelled BN analogues was studied using the BN receptor-positive 7315b pituitary tumour and the CA20948 and AR42J exocrine pancreas tumour cell lines. The tissue distribution of these 111 In-labelled BN analogues was investigated in 7315b tumour-bearing rats. Two DTPA-conjugated analogues, the antagonist [DTPA-Tyr 5 ,D-Phe 6 ]BN(5-13)NHEt and the agonist [DTPA-Pro 1 ,Tyr 4 ]BN showed the highest affinity for the BN receptor on 7315b cell membranes. Despite similar affinity for the BN receptor, the 111 In-labelled agonist, but not the antagonist, was internalized by the BN receptor-positive tumour cells. Consonant with this observation, the agonist [ 111 In-DTPA-Pro 1 ,Tyr 4 ]BN showed much higher specific uptake in BN receptor-positive tissues and tumour than the antagonist [ 111 In-DTPA-Tyr 5 ,D-Phe 6 ]BN(5-13)NHEt, with concordant target to background ratios. We conclude that [ 111 In-DTPA-Pro 1 ,Tyr 4 ]BN has promising characteristics for applications in nuclear medicine. Int. J. Cancer
Pharmaceutics, 2019
Radiolabelled antagonistic bombesin analogues are successfully used for targeting of gastrin-releasing peptide receptors (GRPR) that are overexpressed in prostate cancer. Internalization of antagonistic bombesin analogues is slow. We hypothesized that the use of a non-residualizing radioiodine label might not affect the tumour uptake but would reduce the retention in normal organs, where radiopharmaceutical would be internalized. To test this hypothesis, tyrosine was conjugated via diethylene glycol linker to N-terminus of an antagonistic bombesin analogue RM26 to form Tyr-PEG2-RM26. [111In]In-DOTA-PEG2-RM26 was used as a control with a residualizing label. Tyr-PEG2-RM26 was labelled with 125I with 95% radiochemical purity and retained binding specificity to GRPR. The IC50 values for Tyr-PEG2-RM26 and DOTA-PEG2-RM26 were 1.7 ± 0.3 nM and 3.3 ± 0.5 nM, respectively. The cellular processing of [125I]I-Tyr-PEG2-RM26 by PC-3 cells showed unusually fast internalization. Biodistribution s...
Radiolabeled Peptides: Valuable Tools for the Detection and Treatment of Cancer
Theranostics, 2012
Human cancer cells overexpress many peptide receptors as molecular targets. Radiolabeled peptides that bind with high affinity and specificity to the receptors on tumor cells hold great potential for both diagnostic imaging and targeted radionuclide therapy. The advantage of solid-phase peptide synthesis, the availability of different chelating agents and prosthetic groups and bioconjugation techniques permit the facile preparation of a wide variety of peptide-based targeting molecules with diverse biological and tumor targeting properties. Some of these peptides, including somatostatin, bombesin, vasoactive intestinal peptide, gastrin, neurotensin, exendin and RGD are currently under investigation. It is anticipated that in the near future many of these peptides may find applications in nuclear oncology. This article presents recent developments in the field of small peptides, and their applications in the diagnosis and treatment of cancer.
Cancers
The gastrin-releasing peptide receptor (GRPR) is expressed in high numbers in a variety of human tumors, including the frequently occurring prostate and breast cancers, and therefore provides the rationale for directing diagnostic or therapeutic radionuclides on cancer lesions after administration of anti-GRPR peptide analogs. This concept has been initially explored with analogs of the frog 14-peptide bombesin, suitably modified at the N-terminus with a number of radiometal chelates. Radiotracers that were selected for clinical testing revealed inherent problems associated with these GRPR agonists, related to low metabolic stability, unfavorable abdominal accumulation, and adverse effects. A shift toward GRPR antagonists soon followed, with safer analogs becoming available, whereby, metabolic stability and background clearance issues were gradually improved. Clinical testing of three main major antagonist types led to promising outcomes, but at the same time brought to light severa...