Advanced hormone receptor (HR)-positive(+)/Human epidermal growth factor receptor 2 (HER2)-negative(-) breast cancer represents an important clinical challenge, for which the combination of cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitors with endocrine therapy has emerged as the standard conventional option for both first-line and second-line treatments1–6. The gene discussed is CDK4; the disease is breast carcinoma.