In addition, recently, a phase II study treating 48 heavily pre-treated hormone-receptor (HR)-positive-HER2-low-positive advanced breast cancer patients with the anti-HER2/HER3 ADC zenocutuzumab (in combination with the last endocrine agent on which the patients had previously progressed immediately before the study entry), reported promising preliminary results in terms of clinical activity and safety3. This evidence concerns the gene ERBB2 and breast cancer.