Despite the different ORR between HER2+ and HER2-low patients observed in an informal cross-trial comparison of DESTINY-Breast-03 [5] and DESTINY-Breast-04 [4], we observed no significant difference in the PFS (p = 0.118) or OS (p = 0.521) between the 15 HER2+ and 23 HER2-low breast cancer patients. This evidence concerns the gene ERBB2 and breast cancer.