Evaluation of a Maleimido Derivative of NOTA for Site-Specific Labeling of Affibody Molecules
2011 (English)In: Bioconjugate chemistry, ISSN 1043-1802, E-ISSN 1520-4812, Vol. 22, no 5, 894-902 p.Article in journal (Refereed) Published
Radionuclide molecular imaging has the potential to improve cancer treatment by selection of patients for targeted therapy. Affibody molecules are a class of small (7 kDa) high-affinity targeting proteins with appreciable potential as molecular imaging probes. The NOTA chelator forms stable complexes with a number of radionuclides suitable for SPECT or PET imaging. A maleimidoethylmonoamide NOTA (MMA-NOTA) has been prepared for site-specific labeling of Affibody molecules having a unique C-terminal cysteine. Coupling of the MMA-NOTA to the anti-HER2 Affibody molecule Z(HER2:239S) resulted in a conjugate with an affinity (dissociation constant) to HER2 of 72 pM. Labeling of [MMA-NOTA-Cys(61)]-Z(HER2:239S) with In-111 gave a yield of >95% after 20 min at 60 degrees C. In vitro cell tests demonstrated specific binding of [In-111-MMA-NOTA-Cys(61)]-Z(HER2:239S) to HER2-expressing cell lines. In mice bearing prostate cancer DU-145 xenografts, the tumor uptake of [In-111-MMA-NOTA-Cys(61)]-Z(HER2:239S) was 8.2 +/- 0.9% IA/g and the tumor-to-blood ratio was 31 +/- 1 (4 h postinjection). DU-145 xenografts were clearly visualized by a gamma camera. Direct in vivo comparison of [In-111-MMA-NOTA-Cys(61)]-Z(HER2:239S) and [In-111-MMA-DOTA-Cys(61)]-Z(HER2:239S) demonstrated that both conjugates provided equal radioactivity uptake in tumors, but the tumor-to-organ ratios were better for [In-111-MMA-NOTA-Cys(61)]-Z(HER2:239S) due to more efficient clearance from normal tissues. In conclusion, coupling of MMA-NOTA to a cysteine-containing Affibody molecule resulted in a site-specifically labeled conjugate, which retains high affinity, can be efficiently labeled, and allows for high-contrast imaging.
Place, publisher, year, edition, pages
2011. Vol. 22, no 5, 894-902 p.
Biochemistry and Molecular Biology Biochemistry and Molecular Biology Organic Chemistry
IdentifiersURN: urn:nbn:se:kth:diva-34392DOI: 10.1021/bc100470xISI: 000290691600007ScopusID: 2-s2.0-79959574104OAI: oai:DiVA.org:kth-34392DiVA: diva2:420996
QC 201106072011-06-072011-06-072014-09-29Bibliographically approved