ERBB2 and breast cancer: For a long time, anti-HER2 therapy, such as dual blockade with trastuzumab+pertuzumab and TDM-1, is only prescribed for HER2-positive breast cancer patients [8], but latest research showed that trastuzumab deruxtecan (T-DXd) shall also benefit patients with HER2-low breast cancer [9, 10], which has been validated by one multicenter, randomized controlled trial (RCT) enrolling 557 patients with HER2-low breast cancer (DESTINY-Breast 04), presenting patients treated by T-DXd had significantly longer progression-free and overall survival time than those by only chemotherapy treatment [11].