A real-world study in the United States (40) retrospectively analyzed the efficacy of 41 HR+/HER2- BC patients at the University of Pittsburgh Medical Centers in Roswell and Pittsburgh, USA, who were treated with everolimus follow-up after progression on perphenazine therapy, and the results showed that the median PFS was 4.2 months, and the median OS reached approximately 18 months. The gene discussed is ERBB2; the disease is breast cancer.