Use of Coiled-Coil Affinity Peptides to Manufacture Antibody Conjugates

Antibody-drug conjugates are revolutionizing cancer treatment. However, their manufacturing still requires improvements in conjugation technology, especially for the control of the drug-to-antibody ratio (DAR). Here, we investigate the use of the de novo designed coiled-coil heterodimer, composed of the Ecoil and Kcoil peptides, as a new strategy for generating antibody conjugates with high homogeneity and a controllable DAR. More precisely, we investigated the assembly, stability, and tumor targeting of two conjugated antibodies made of (1) trastuzumab with C-terminal Ecoils (TZM-Ecoil) noncovalently paired with Kcoil peptides fused to the monomeric red fluorescent protein (Kcoil-mRFP), yielding TZM-E/K-mRFP or (2) TZM-Ecoil noncovalently paired to Kcoil peptide covalently linked to the fluorescent dye CF750 (Kcoil-CF750), yielding TZM-E/K-CF750. Results from the in vitro stability assessment of these complexes in blood serum revealed that their integrity was maintained. Furthermore, in vivo biodistribution and tumor localization data using a HER2-expressing SKOV3 xenograft mouse model indicated efficient tumor targeting and retention for up to 10 days postinjection of the TZM-E/K-CF750 conjugate.