Evaluation of a maleimido derivative of NOTA for site-specific labeling of affibody molecules

Vladimir Tolmachev, Mohamed Altai, Mattias Sandström, Anna Perols, Amelie Eriksson Karlström, Frederic Boschetti, Anna Orlova

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


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 (MMANOTA) 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 ZHER2:2395 resulted in a conjugate with an affinity (dissociation constant) to HER2 of 72 pM. Labeling of [MMA-NOTA-Cys61]-ZHER2:2395 with 111In gave a yield of >95% after 20 min at 60 °C. In vitro cell tests demonstrated specific binding of [111In-MMA-NOTA-Cys 61]-ZHER2:2395 to HER2-expressing cell lines. In mice bearing prostate cancer DU-145 xenografts, the tumor uptake of [ 111In-MMA-NOTA-Cys61]-ZHER2:2395 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 [111In-MMA-NOTA-Cys61]-ZHER2:2395 and [ 111In-MMA-DOTA-Cys61]-ZHER2:2395 demonstrated that both conjugates provided equal radioactivity uptake in tumors, but the tumor-to-organ ratios were better for [111In-MMANOTA-Cys 61]-ZHER2:2395 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.

Original languageEnglish
Pages (from-to)894-902
Number of pages9
JournalBioconjugate Chemistry
Issue number5
Publication statusPublished - 18 May 2011
Externally publishedYes

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biomedical Engineering
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry

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