"L19K was synthesized by CPC Scientific and comprised the sequence NO2A-PEG4-GGNECDIARMWEWECFERK-CONH2, with Cys-Cys disulfide bridge and polyethylene glycol (PEG4) as a spacer between peptide and chelator. "
Abstract
Imaging agents based on peptide probes have desirable pharmacokinetic properties provided that they have high affinities for their target in vivo. An approach to improve a peptide ligand’s affinity for its target is to make this interaction covalent and irreversible. For this purpose, we evaluated a 64Cu-labeled affinity peptide tag, 64Cu-L19K-(5-fluoro-2,4-dinitrobenzene) (64Cu-L19K-FDNB), which binds covalently and irreversibly to vascular endothelial growth factor (VEGF) as a PET imaging agent. We compared the in vivo properties of 64Cu-L19K-FDNB in VEGF-expressing tumor xenografts with its noncovalent binding analogs, 64Cu-L19K-(2,4-dinitrophenyl) (64Cu-L19K-DNP) and 64Cu-L19K. Methods: The L19K peptide (GGNECDIARMWEWECFERK-CONH2) was constructed with 1,4,7-triazacyclononane-1,4,7-triacetic acid at the N terminus for radiolabeling with 64Cu with a polyethylene glycol spacer between peptide and chelate. 1,5-difluoro-2,4-dinitrobenzene was conjugated at the C-terminal lysine for cross-linking to VEGF, resulting in L19K-FDNB. 64Cu-L19K-FDNB was assayed for covalent binding to VEGF in vitro. As a control, L19K was conjugated to 1-fluoro-2,4-dinitrobenzene, resulting in L19K-DNP. PET imaging and biodistribution studies of 64Cu-L19K-FDNB, 64Cu-L19K-DNP, and the native 64Cu-L19K were compared in HCT-116 xenografts. Blocking studies of 64Cu-L19K-FDNB was performed with a coinjection of excess unlabeled L19K-FDNB. Results: In vitro binding studies confirmed the covalent and irreversible binding of 64Cu-L19K-FDNB to VEGF, whereas 64Cu-L19K-DNP and 64Cu-L19K did not bind covalently. PET imaging showed higher tumor uptake with 64Cu-L19K-FDNB than with 64Cu-L19K-DNP and 64Cu-L19K, with mean standardized uptake values of 0.62 ± 0.05, 0.18 ± 0.06, and 0.34 ± 0.14, respectively, at 24 h after injection (P < 0.05), and 0.53 ± 0.05, 0.32 ± 0.14, and 0.30 ± 0.09, respectively, at 48 h after injection (P < 0.05). Blocking studies with 64Cu-L19K-FDNB in the presence of excess unlabeled peptide showed a 53% reduction in tumor uptake at 48 h after injection. Conclusion: In this proof-of-concept study, the use of a covalent binding peptide ligand against VEGF improves tracer accumulation at the tumor site in vivo, compared with its noncovalent binding peptide analogs. This technique is a promising tool to enhance the potency of peptide probes as imaging agents.
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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.).."