Intriguingly, this finding aligns seamlessly with the retrospective MONALEESA study, where PAM50 analysis revealed that the clinical efficacy of CDK 4/6 inhibitors combined with endocrine therapy is not universally compromised in HR+/HER2-low breast cancers, and subsets such as luminal B, HER2-enriched, and basic-like phenotypes had notably lower efficacy compared with the luminal A subtype7. Here, ERBB2 is linked to breast cancer.