STAT3 and neoplasm: However, lack of new tumor antigens, the insufficient number of tumor-infiltrating lymphocytes (TILs) [17], and overexpression of immunosuppressive molecules, such as programmed death 1/programmed death-ligand 1 [18], wingless-type MMTV integration site family, member 5A [19], and signal transducer and activator of transcription 3 (STAT3) inhibitor [20], inhibit tumor immunology, leading to the deterioration of MM-immune microenvironment.