Direct site-specific radiolabeling of an Affibody protein with 4-[18F]fluorobenzaldehyde via oxime chemistry.
ABSTRACT In this study, we introduce a methodology for preparing 18F-labeled Affibody protein, specifically 18F-Anti-HER2 dimeric Affibody (14 kDa), for in vivo imaging of HER2neu with positron emission tomography (PET).
We have used 4-[18F]fluorobenzaldehyde as a synthon to prepare 18F-Anti-HER2 Affibody. Aminooxy-functionalized Affibody (Anti-HER2-ONH2) was incubated with 4-[18F]fluorobenzaldehyde in ammonium acetate buffer at pH 4 in the presence of methanol at 70 degrees C for 15 min. The resulting 18F-labeled Affibody molecule was evaluated as a PET probe in xenograft models expressing HER2.
We have successfully prepared 18F-Anti-HER2 dimeric Affibody (14 kDa), N-(4-[18F]fluorobenzylidine)oxime-Anti-HER2 Affibody, [18F]FBO-Anti-HER2, in 26-30% radiochemical yields (decay corrected). High-contrast small-animal PET images with relatively moderate tumor uptake (1.79 +/- 0.40% ID/g) were observed for the 18F-Anti-HER2 Affibody.
Site-specific 18F-labeled Affibody against HER2 has been synthesized via chemoselective oxime formation between an aminooxy-functionalized Affibody and 18F-fluorobenzaldehyde. The results have implications for radiolabeling of other affibodies and macromolecules and should also be important for advancing Affibody imaging with PET.
- SourceAvailable from: Quang-De Nguyen[Show abstract] [Hide abstract]
ABSTRACT: The chemokine receptor CXCR4 is overexpressed in a variety of cancers including breast, prostate and lung cancer. Expression is also associated with invasion and metastasis. The possibility to image and quantify CXCR4 expression in vivo would be a valuable tool in the clinic to aid treatment regimens and to potentially understand the underlying biology of metastasis. Herein we describe the synthesis and the radiolabelling of an 18F-labelled cyclic pentapeptide, [18F]CCIC-0007 designed to bind to the extracellular domains of CXCR4. Radiolabelling was performed via conjugation of [18F]fluorobenzaldehyde with an aminooxy functionalised cyclopentapeptide. Typically, starting with 1.10 GBq (30 mCi) of aqueous [18F]fluoride, 105 MBq (2.85 mCi) of the formulated tracer was obtained within 2.5 h (23 ± 8% dc rcy, 8% EOS yield). Tissue pharmacokinetic studies in mice demonstrated rapid blood clearance, together with biliary and renal elimination.Journal of Fluorine Chemistry 03/2012; 135:200–206. DOI:10.1016/j.jfluchem.2011.11.003 · 1.95 Impact Factor
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ABSTRACT: Affibody molecules are small scaffold-based affinity proteins with promising properties as probes for radionuclide-based molecular imaging. However, a high reabsorption of radiolabeled Affibody molecules in kidneys is an issue. We have shown that the use of 125I-3-iodo-((4-hydroxyphenyl)ethyl)maleimide (IHPEM) for site-specific labeling of cysteine-containing Affibody molecules provides high tumor uptake but low radioactivity retention in kidneys. We hypothesized that the use of 4-iodophenethylmaleimide (IPEM) would further reduce renal retention of radioactivity because of higher lipophilicity of radiometabolites. An anti-human epidermal growth factor receptor type 2 (HER2) Affibody molecule (ZHER2:2395) was labeled using 125I-IPEM with an overall yield of 45±3 %. 125I-IPEM-ZHER2:2395 bound specifically to HER2-expressing human ovarian carcinoma cells (SKOV-3 cell line). In NMRI mice, the renal uptake of 125I-IPEM-ZHER2:2395 (24±2 and 5.7±0.3 % IA g−1at 1 and 4 h after injection, respectively) was significantly lower than uptake of 125I-IHPEM-ZHER2:2395 (50±8 and 12±2 % IA g−1at 1 and 4 h after injection, respectively). In conclusion, the use of a more lipophilic linker for the radioiodination of Affibody molecules reduces renal radioactivity.ChemistryOpen 04/2015; 9999. DOI:10.1002/open.201402097 · 2.94 Impact Factor