PET Imaging of HER2-Positive Tumors with Cu-64-Labeled Affibody Molecules

摘要: Previous studies has demonstrated the utility of human epidermal growth factor receptor type 2 (HER2) as an attractive target for cancer molecular imaging and therapy. An affibody protein with strong binding affinity HER2, ZHER2:342, been reported. Various methods chelator conjugation radiolabeling HER2 molecules have described in literature including N-terminal conjugation, C-terminal other methods. Cu-64 recently extensively evaluated due to its half-life, decay properties, availability. Our goal was optimize method this molecule Cu-64, translate a positron emission tomography (PET) probe best vivo performance clinical PET HER2-positive cancers. In our study, three anti-HER2 proteins-based probes were prepared, their mice bearing subcutaneous SKOV3 tumors. The analogues, Ac-Cys-ZHER2:342, Ac-ZHER2:342(Cys39), Ac-ZHER2:342-Cys, synthesized using solid phase peptide synthesis method. purified small proteins site-specifically conjugated maleimide-functionalized chelator, 1,4,7,10-tetraazacyclododecane-1,4,7-tris- aceticacid-10-maleimidethylacetamide (maleimido-mono-amide-DOTA). resulting DOTA-affibody conjugates then radiolabeled Cu-64. Cell uptake assay probes, [64Cu]DOTA-Cys-ZHER2:342, [64Cu]DOTA-ZHER2:342(Cys39), [64Cu]DOTA-ZHER2:342-Cys, performed ovarian carcinoma cells at 4 37 °C. affinities peptides tested by cell saturation cells. imaging, biodistribution, metabolic stability assays showed high specific incubation Cu-64-labeled affibodies (KD) radio analysis low nanomolar range ranking [64Cu]DOTA-Cys-ZHER2:342 (25.2 ± 9.2 nM) ≈ [64Cu]DOTA-ZHER2:342-Cys (32.6 ± 14.7 nM) > [64Cu]DOTA-ZHER2:342(Cys39) (77.6 ± 22.2 nM). vitro metabolite study revealed that all stable enough applications, while highest stability. small-animal further fast tumor targeting, good accumulation, normal tissue contrast probes. For 24 h are 4.0 ± 1.0 % ID/g, 4.0 ± 0.8 %ID/g, 4.3 ± 0.7 respectively (mean ± SD, n = 4). Co-injection non-labeled confirmed specificities compounds reduction. ZHER2:342 analogues display excellent targeting ability quality. Although varied position radiometal labeling these there is no significant difference uptakes among stands out most superior because