ERBB2 and breast cancer: For 66 HER2-positive (IHC 2+ and FISH+ or IHC 3+) breast cancer patients, all had prior HER2-targeted therapy with a median prior line of 4, including 100% (66/66) who received trastuzumab, 89.4% (59/66) who received anti-HER2 TKIs, 28.8% (19/66) who received pertuzumab, and 25.8% (17/66) who received anti-HER2 ADCs, among whom 11 received T-DM1, 5 received ARX-78815, and 1 received TAA013.