Strikingly, this investigation also demonstrated that neratinib reversed the efficacy of CDK4/6 inhibitor and endocrine therapy by reducing HER2 mRNA stability in HR+/HER2-low breast cancer via the interaction of HER2’s 3’-UTR region with hsa-miR-23a-5p, and discovered that even when reducing neratinib dosage to the standard half dose (20 mg/kg), it remained highly effective and well-tolerated. This evidence concerns the gene CDK4 and breast carcinoma.