A fully human anti-HER3 monoclonal antibody( patritumab ) that is covalently linked to a topoisomerase I inhibitor payload via an effective, tumor-specific, tetrapeptide-based cleavable linker is what makes up the human epidermal growth factor receptor 3( HER3 )- directed antibody-drug conjugate. A window-of-opportunity study called TOT-HER3 is intended to evaluate the biological activity of patients with primary operable HER2 – negative early breast cancer during short-term( 21 days ) pre-operative treatment. It is based on the CelTIL score, which is 0. 8 tumor cellularity( in %) and 1. 3 tumor-infiltrating lymphocytes( tILs ), respectively.