CD22 and cancer: During the last decades a wide range of immunotherapeutic approaches have been introduced for cancer treatment, such as programmed cell death protein ligand-1 (PDL-1) inhibitors, cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) blockers, CD22-targeting therapy with Inotuzumab ozogamicin and targeted T-cell therapy through chimeric antigen receptor (CAR)-T cells or bi-specific T-cell engagers leading to significant improvements in overall survival for a number of cancer patients.