Highly reactive trans-cyclooctene tags with improved stability for diels-alder chemistry in living systems

Raffaella Rossin, Sandra M. van den Bosch, Wolter ten Hoeve, Marco Carvelli, Ron M. Versteegen, Johan Lub, Marc S. Robillard

Research output: Contribution to journalArticleAcademicpeer-review

206 Citations (Scopus)


One of the challenges of pretargeted radioimmunotherapy, which centers on the capture of a radiolabeled probe by a preinjected tumor-bound antibody, is the potential immunogenicity of biological capturing systems. A bioorthogonal chemical approach may circumvent this drawback, but effective in vivo chemistry in mice, larger animals, and eventually humans, requires very high reagent reactivity, sufficient stability, and retained selectivity. We report here that the reactivity of the fastest bioorthogonal reaction, the inverse-electron- demand-Diels-Alder cycloaddition between a tetrazine probe and a trans-cyclooctene-tagged antibody, can be increased 10-fold (k2 = 2.7 × 105 M-1 s-1) via the trans-cyclooctene, approaching the speed of biological interactions, while also increasing its stability. This was enabled by the finding that the trans-cyclooctene tag is probably deactivated through isomerization to the unreactive cis-cyclooctene isomer by interactions with copper-containing proteins, and that increasing the steric hindrance on the tag can impede this process. Next, we found that the higher reactivity of axial vs equatorial linked TCO can be augmented by the choice of linker. The new, stabilized, and more reactive tag allowed for improved tumor-to-nontumor ratios in pretargeted tumor-bearing mice.

Original languageEnglish
Pages (from-to)1210-1217
Number of pages8
JournalBioconjugate Chemistry
Issue number7
Publication statusPublished - 17 Jul 2013


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