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.