An antibody-drug conjugate (ADC) composed of a monoclonal antibody against the tumor-associated antigen (TAA) B-cell antigen receptor complex-associated protein beta chain (CD79b; B-cell-specific glycoprotein B29) conjugated to a topoisomerase-1 inhibitor, with potential antineoplastic activity. Upon intravenous administration, the monoclonal antibody moiety of anti-CD79b ADC SHR-A1912 targets and binds to CD79b expressed on tumor cells. Upon binding and internalization, the topoisomerase-1 inhibitor is released and inhibits DNA topoisomerase I activity, thereby inhibiting DNA replication and resulting in cell cycle arrest and apoptosis in tumor cells expressing CD79b. CD79b, a critical receptor for successful B-cell development and part of the B-cell receptor (BCR) signaling complex, is widely expressed in certain subtypes of B-cell lymphomas.