Ado-trastuzumab emtansine (T-DM1) demonstrates favorable efficacy in breast cancer treatment but is frequently associated with thrombocytopenia. Multiple studies indicate that Asian populations face a higher risk of developing thrombocytopenia during T-DM1 therapy, with incidence rates ranging from 52.5% to 69.8% and ≥Grade 3 rates between 29.8% and 45.0%. Severe thrombocytopenia not only increases bleeding risks but may also necessitate T-DM1 dose delays or reductions, thereby compromising treatment efficacy and diminishing patient survival and quality of life. Herombopag selectively binds to the transmembrane region of TPO-R, activating TPO-R-dependent STAT and MAPK signaling pathways. This effectively stimulates megakaryocyte proliferation and differentiation, promoting thrombopoiesis. However, high-level evidence supporting the use of Herombopag for primary prevention of T-DM1-induced thrombocytopenia in breast cancer remains lacking.