CD79B, a transmembrane protein encoded by the *CD79B* gene, is a critical component of the B-cell receptor (BCR) complex. It pairs with CD79A to form a heterodimer that non-covalently associates with surface immunoglobulin (Ig), facilitating BCR signaling upon antigen recognition. CD79B contains an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic domain, which is essential for initiating downstream signaling cascades that regulate B-cell development, activation, and survival. Dysregulation of BCR signaling is implicated in B-cell malignancies, making CD79B a therapeutic target.
Antibodies targeting CD79B have emerged as promising tools in both research and clinical settings. In diagnostics, anti-CD79B antibodies are used to identify B-cell lineage in lymphoid malignancies via flow cytometry or immunohistochemistry. Therapeutically, monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs) against CD79B are being explored. For example, polatuzumab vedotin, an ADC linking an anti-CD79B mAb to the cytotoxic agent monomethyl auristatin E (MMAE), has shown efficacy in treating relapsed/refractory diffuse large B-cell lymphoma (DLBCL) by selectively delivering chemotherapy to malignant B cells.
Despite progress, challenges remain, including tumor heterogeneity in CD79B expression and resistance mechanisms such as antigen loss or impaired ADC internalization. Ongoing research focuses on optimizing antibody design, identifying predictive biomarkers, and combining CD79B-targeted therapies with other agents (e.g., anti-CD20 antibodies, kinase inhibitors) to enhance efficacy. These efforts underscore CD79B's role as a pivotal biomarker and therapeutic target in B-cell disorders.