CD22 as a Target for Hematological Malignancies and Autoimmune Diseases

CD22 is a critical inhibitory coreceptor predominantly expressed on the surface of B cells, playing a pivotal role in modulating B cell receptor (BCR) signaling and maintaining immune homeostasis. Its high B cell lineage specificity, rapid internalization capacity, and signal attenuation mediated by immunoreceptor tyrosine-based inhibitory motifs (ITIMs) render it an ideal therapeutic target for B cell-related pathologies. In recent years, CD22-targeted therapeutic strategies have demonstrated significant clinical breakthroughs in the treatment of hematological malignancies and autoimmune diseases. These strategies encompass immunotoxins, radioimmunoconjugates, antibody–drug conjugates (ADCs), bispecific antibodies, and chimeric antigen receptor (CAR) T cell therapy. Notably, while monotherapies have achieved high response rates, dual-targeting approaches (e.g., CD19/CD22 CAR-T) have further mitigated the risk of antigen escape and profoundly enhanced long-term durable efficacy. This review systematically summarizes the molecular mechanisms of CD22 and the latest clinical advancements in its targeted therapies. Furthermore, we highlight the promising translational potential of CD22-targeted strategies—particularly CAR-T cell therapy—from oncology to the management of autoimmune disorders, outlining future research priorities within this rapidly evolving field.