ERBB2 and breast cancer: Finally, it is essential to redefine, with new dedicated trials, the role of ER-low (1–9%) BC which, biologically and prognostically very similar to TNBC, could potentially benefit from the addition of immunotherapy to CHT and the role of HER-2 low [score 1+ or 2+ not amplified in fluorescence in situ hybridization (FISH)] BC in the light of recent results of efficacy of trastuzumab deruxtecan in advanced BC HER-2 low.