SyMO-Chem BV

The bioorthogonal tetrazine-triggered cleavage of trans-cyclooctene(TCO)-linked payloads has strong potential for widespread use in drug delivery and in particular in click-cleavable ADCs, but clin. translation is hampered by an inverse correlation between click reactivity and payload release yield.This requires the use of high doses of relatively less reactive tetrazines to drive in vivo TCO reactions to completion and achieve sufficient payload release.Herein we report that the main cause for the low release when using the highly reactive bis-(2-pyridinyl)-tetrazine is the stability of the initially formed 4,5-dihydropyridazine product, precluding tautomerization to the releasing 1,4-dihydropyridazine tautomer.We demonstrate that efficient tautomerization and payload elimination can be achieved by ortho-substituting bis-pyridinyl-tetrazines with hydrogen-bonding hydroxyl or amido groups, thereby achieving a.o. release yields of 96% with 18-fold more reactive tetrazines.Applied to on-tumor activation of a click-cleavable ADC in mice, the new tetrazines afforded near-quant. ADC conversion at a ca. 10- to 20-fold lower dose than what was previously needed, resulting in a strong therapeutic response.

Supramol. polymers have shown to be powerful scaffolds for tissue engineering applications.Supramol. biomaterials functionalized with ureidopyrimidinone (UPy) moieties, which dimerize via quadruple hydrogen-bond formation, are eminently suitable for this purpose.The conjugation of the UPy moiety to biol. active peptides ensures adequate integration into the supramol. UPy polymer matrix.The structural complexity of UPy-peptide conjugates makes their synthesis challenging and until recently low yielding, thus restricted the access to structurally diverse derivativesHere we report optimization studies of a convergent solid-phase based synthesis of UPy-modified peptides.The peptide moiety is synthesized using standard Fmoc solid-phase synthesis and the UPy fragment is introduced on the solid-phase simplifying the synthesis and purification of the final UPy-peptide conjugate.The convergent nature of the synthesis reduces the number of synthetic steps in the longest linear sequence compared to other synthetic approaches.We demonstrate the utility of the optimized route by synthesizing a diverse range of biol. active UPy-peptide bioconjugates in multimilligram scale for diverse biomaterial applications. 1 Introduction 2 Divergent Synthesis 3 Convergent Synthesis 4 UPy-Amine Strategy 5 UPy-Carboxylic Acid Strategy 6 Conclusion.