The present invention relates to the field of
bioconjugation of functional entities (payloads) to targeting agents, in particular biological targeting agents such as
antibody drug conjugates (ADCs), in which one or more
payload molecules are conjugated to a targeting agent, for example a
monoclonal antibody. More specifically, the present invention relates to novel hydrophilic
tetrazine molecules and their preparation, which allow more efficient conjugation of
payload molecules to targeting agents such as
monoclonal antibodies. The present invention also relates to certain
tetrazine intermediates useful for the preparation of corresponding functionalized
payload molecules. The present invention also relates to the respective conjugates, in particular bioconjugates, and methods for their preparation. The present invention also relates to the medical use of such conjugates of the present invention, to the corresponding pharmaceutical compositions, and to the corresponding diagnostic and analytical kits.