Overexpression of LAG-3 has been identified on tumor-infiltrating lymphocytes (TILs) in a number of solid tumors, including melanoma, glioma, NSCLC, head and neck squamous cell carcinoma (HNSCC), breast cancer (BC), gastric cancer (GC), and lymphoma, as well as in leukemia [64–75]. The gene discussed is LAG3; the disease is leukemia.