Using a mouse model, Thon et al. reported that T-DM1-induced thrombocytopenia involves HER2- and FcγRIIa-independent pathways, since megakaryocytes/platelets do not express the HER2 and mouse cells do not express the FcγRIIa receptors for human IgGs [21]. Here, ERBB2 is linked to Thrombocytopenia.