ERBB2 and gastric cancer: In a few particular tumor types, treatment with custom-tailored tyrosine kinase inhibitors or immunotherapeutic agents has become possible, such as trastuzumab in human epidermal growth factor receptor 2 (HER2-positive) breast cancer or gastric cancer [7,8], imatinib in KIT+ gastrointestinal stromal tumor (GIST) [9], and B-rapidly accelerated fibrosarcoma (BRAF)-directed therapy with vemurafenib or dabrafenib/trametinib in melanoma [10].