MRG002 consists of a humanized anti-HER2 with a linker that carries ~3.8 MMAE [126] that showed tolerable toxicity and an antitumor effect in HER2+ breast cancer PDX and in mouse xenografts that was more efficient than trastuzumab and T-DM1, since it exhibited results even in T-DM1-resistant models [126]. This evidence concerns the gene ERBB2 and breast cancer.