Antibody-drug conjugates (ADCs) are novel immunotherapeutics that combine the antibody-mediated targeting to tumor cells with the cytotoxic effect of toxic molecules. ADCs have recently shown clinical success, after several rounds of optimization for the conjugation chemistry, the conjugation spacer and the cytotoxin. We have developed a new conjugation technology that stabilizes and simplifies the conjugation spacer requirements. In order to enable these improvements, and to homogenize the conjugates, we produce the antibodies in specialized cells (HEK293S GlycoDelete). In the current IOF StarTT project, we aim to further optimize the conjugation protocol and to validate our initial functional tests (anti-tumor cytotoxicity) in mouse models. Furthermore, we aim to adapt CHO cells, the main production host cells for antibodies in industry, with the GlycoDelete technology.