ERBB2 and breast cancer: The phase III KAITLIN study aimed to improve the efficacy and reduce the toxicity of high-risk HER2-positive early breast cancer treatment by replacing taxanes and trastuzumab with T-DM1 [68]; however, the primary endpoint was not met, and both arms achieved favorable invasive disease-free survival, with trastuzumab plus pertuzumab plus chemotherapy remaining the standard of care for high-risk HER2-positive early breast cancer.