"[RGD-Glu-(DO3A)-6-Ahx-RM2], [Cyclo-(Arg-Gly-Asp-D-Tyr- Lys)-(DO3A)-Glu-(6-Ahx-D-Phe-Gln-Trp-Ala-Val-Gly-His- Sta-Leu-NH2)], was purchased from CPC Scientific (Sunnyvale, CA, USA)."
Abstract
In the present study, we report the metallation, characterization, in vitro and in vivo studies comparing 67Ga/64Cu-radiolabeled bivalent peptide ligands as targeting probes with the capability of targeting the αvβ3 integrin or the gastrin releasing peptide receptor (GRPR) for preclinical and clinical use in single-photon emission computed tomography (SPECT) or positron emission tomography (PET) imaging of prostate tumors. The ligand precursor, [RGD-Glu-6-Ahx-RM2] (RGD: Arg-Gly-Asp; Glu: glutamic acid; 6-Ahx: 6-amino hexanoic acid; RM2: D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2), was conjugated to a DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) bifunctional chelator (BFCA), purified by reversed-phase high-performance liquid chromatography (RP-HPLC), characterized via electrospray ionization-mass spectrometry (ESI-MS), and radiolabeled with 67Ga or 64Cu. The in vitro investigations of the binding affinities of the natural-metallated ligands for the GRPR or the αvβ3 integrin were conducted via competitive displacement binding assays in human prostate PC-3 and glioblastoma U87-MG cell lines. Following stability investigations via RP-HPLC, the in vivo evaluations of the Ga67/Cu64-radiolabeled ligands were performed in CF-1 mice and SCID mice bearing PC-3 tumors. The in vitro studies of the natural-metallated ligands showed high binding affinities for the GRPR (7.78 ± 2.42, 8.64 ± 2.16 nM; Ga, Cu respectively) and moderate binding affinity for the αvβ3 integrin receptor (307 ± 40.0, 308 ± 42.6 nM; Ga, Cu respectively). In vivo biodistribution studies displayed high tumor uptake (7.44 ± 1.09, 10.85 ±4.02% ID/g at 1 h post-intravenous injection; 67Ga, 64Cu respectively) and prolonged tumor retention (4.89 ± 1.11, 4.09 ±0.96% ID/g at 24 h post-intravenous injection; 67Ga, 64Cu respectively) in PC-3 tumor-bearing mice. Micro-single photon emission computed tomography (microSPECT) and micro-positron emission computed tomography (microPET) molecular imaging studies produced high-quality, high-contrast images in PC-3 tumor-bearing mice at 18 h post-intravenous injection. Both radiolabeled ligands show satisfactory tumor uptake and retention in PC-3 tumor-bearing mice. However, [RGD-Glu-(67Ga-DO3A)-6-Ahx-RM2] demonstrates superior pharmacokinetic profiles to [RGD-Glu-(64Cu-DO3A)-6-Ahx-RM2], presumably due to more favorable in vivo stability.
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Boehm, M., Beaumont, K., Jones, R.M., Kalgutkar, A.S., Zhang, L., Atkinson, K., Bai, G., Brown, J.A., Eng, H., Goetz, G.H. and Holder, B.R. Journal of Medicinal Chemistry (2017).
- Pfizer Worldwide Research & Development, Cambridge, Massachusetts 02139, United States
- Pfizer Worldwide Research & Development, Groton, Connecticut 06340, United States
The chemokine receptor CXCR7 is an attractive target for a variety of diseases. While several small-molecule modulators of CXCR7 have been reported, peptidic macrocycles may provide advantages in terms of potency, selectivity, and reduced off-target activity
Bainbridge, Travis W., et al. Scientific Reports 7.1 (2017): 12524.
- Protein Chemistry, Molecular Oncology, Discovery Chemistry, Cancer Immunology, and Neuroscience. Genentech Inc., South San Francisco, CA, 94080, USA
"ANP FAP and aP NIRF were synthesized by CPC Scientific (Sunnyvale, CA)… Another internally-quenched FRET peptide substrate (ANPFAP) for FAP has recently been reported and demonstrated for use as an activity-based, in vivo imaging tool. The peptide sequence contains two internal Gly-Pro dipeptide motifs, susceptible to FAP cleavage and a Cy5.5/QSY21, quenched-FRET pair."
Coorens, Maarten, et al. The Journal of Immunology 199.4 (2017): 1418-1428.
"CATH-2 and LL-37 were synthesized by Fmoc-chemistry at CPC Scientific (Sunnyvale, CA)."
Tcholakov, I., Grimshaw, C.E., Shi, L., Kiryanov, A., Murphy, S.T., Larson, C.J., Plonowski, A. and Ermolieff, J. Bioscience Reports 37, no. 3 (2017): BSR20170275.
- Departments of In Vitro Pharmacology, Immunology, Enzymology and Biophysical Chemistry, Medicinal Chemistry, External Innovation, Metabolic Disease, In Vitro Pharmacology, and Gastrointestinal and Enterology Discovery Unit, Takeda California, Inc., 10410 Science Center Drive, San Diego, CA 92121, U.S.A
The substrate used for our PHD2 kinetic study was a 17-mer peptide mimicking the sequence of HIF-1a surrounding the Pro564 residue hydroxylated by the PHD enzymes (Biotin-DLEMLAPYIPMDDDFQL). The substrate used for FIH1 was a 34-mer peptide mimicking the sequence of HIF-1α surrounding residue Asn803 (DESGLPQLTSYDCEVNAPIQGSRNLLQGEELLRAL). Both peptides were synthesized by CPC Scientific Inc.
Wilson, Sarah S., et al. PLoS Pathogens 13.6 (2017): e1006446.
"Cryptdin 2 (UniProtKB: P28309, LRDLVCYCRTRGCKRRERMNGTCRKGHLMYTLCCR)... obtained by oxidative refolding of partially purified linear peptides (synthesized by CPC Scientific...) and purifying the correctly folded species by reverse-phase high-pressure liquid chromatography (RP-HPLC). Purity was determined by analytical RP-HPLC, and the mass of the disulfide-bonded peptides was verified by high mass accuracy liquid chromatography-mass spectrometry."
Sattiraju, A., et al. Oncotarget 2017, 8 (26), 42997-43007.
For Ac-225 labeling, the prepared DOTA-Pep-1L (CPC-scientific, San Jose, CA) was incubated with Ac-225 at 70°C for 50 minutes. The TLC plates were scanned on a BioScan Imaging Scanner. Cu-64 was purchased from Washington University in St. Louis. The custom peptide specific to IL13RA2 and a scrambled peptide were conjugated with NOTA by CPC scientific Inc (San Jose, CA). Both the peptides, Pep-1L and scrambled peptide-NOTA were radiolabeled with Cu-64 according to the previously reported methods [15].
Puthenveetil, Sujiet, et al. PloS One 12.5 (2017): e0178452.
- Worldwide Medicinal Chemistry, Pfizer Global R&D, Groton, Connecticut, United States of America.
- Pfizer Oncology Research, Pearl River, NY, United States of America.
"Peptide-payload conjugate (7) was prepared by reacting 2mM aizoacetyl-Ser-Lys-Gly-Ser-Lys (CPC scientific, inc. Sunnywale, CA) with 8 mM NHS-ester payload [19] in 50% Dimethyl sulfoxide (DMSO), 50 mM borate buffer pH 8.5 for 2 h at 37°C."
Kwon, Ester J., et al. Advanced Materials 29.35 (2017).
"[..] synthesized for initial screening with FAM-conjugated lysine at the C-terminal end of the membrane-interactive peptide and with or without D[KLAKLAK]2 on the C-terminus using standard Fmoc chemistry[..] All peptides were synthesized with N-terminal myristic acid and C-terminal amine. [..] larger quantities of the peptides were synthesized by CPC Scientific to 90% purity"
Noland, Cameron L., et al. Proceedings of the National Academy of Sciences 114.30 (2017): E6044-E6053.
- Departments of Structural Biology, Infectious Diseases, Biochemical and Cellular Pharmacology, Pathology, Translational Immunology, and Biomolecular Resource Group, Genentech, Inc., South San Francisco, CA 94080.
"..peptide substrates were synthesized based on the Pal lipoprotein, Pal peptideshort (Pam2Cys-SSNKNGGK-Biotin; CPC Scientific, Inc.).."