Homogeneous, site-specifically conjugated antibodies have shown to result in antibody-drug conjugates (ADCs) with improved efficacy and tolerability compared to stochastically conjugated ADCs. However, precisely controlling the drug-load as well as attaching multiple payload moieties on the antibody remains challenging. Here, we demonstrate the simple and direct modification of native IgG-antibodies at the residue glutamine 295 (Q295) without the need for any protein engineering at …