SPH4336, a novel, highly selective oral CDK4/6i, has demonstrated significant potential in breast cancer treatment (Clinical Trial Registration Number: NCT05905614) [31], A phase II clinical study (CTR20231425) is currently ongoing to evaluate its combination with ET in HR + /HER2–MBC with BM, offering renewed hope for BCBM patients. The gene discussed is ERBB2; the disease is breast carcinoma.