Since then, there have been eleven FDA-approved ADCs (Table 3) for targeting various tumor antigens, such as CD19, CD22, CD30, CD33, and CD79b in blood cancers (myeloma, lymphoma, and leukemia), and HER2, tissue factor, folate factor alpha, Nectin-4, and Trop-2 in solid cancers (NSCLC, breast cancer, gastric cancer, and ovarian cancer, among others [250], and many more are in advanced stages of clinical trials. The gene discussed is ERBB2; the disease is breast cancer.