ERBB2 and B-cell chronic lymphocytic leukemia: Immunotherapeutic antibodies used in clinics target cell antigens, such as CD20 in chronic lymphocytic leukemia (Obinutuzumab, Ofatumumab); CD20 in B-cell lymphoma (Rituximab); cell receptors, e.g., human epidermal growth factor receptor 2 (HER2) in breast cancer (Trastuzumab, Pertuzumab); as well as epidermal growth factor receptor (EGFR) in colorectal cancer and head and neck squamous cell carcinoma (HNSCC) (Cetuximab) [26].