Presently, ongoing clinical trials focusing on neoadjuvant endocrine therapy predominantly involve CDK4/6 inhibitors, such as the neoadjuvant-palbociclib (NeoPal) and NeoPalAna studies.6 Nevertheless, the use of CDK4/6 inhibitors has been associated with a notable increase in adverse effects, including diarrhea, nausea, neutropenia, leukopenia, thrombocytopenia, and fatigue.7,8. This evidence concerns the gene CDK4 and neutropenia.