Naratuximab emtansine (also known as IMGN-529 or KVA-12123) is an investigational antibody-drug conjugate (ADC) consisting of a humanized monoclonal antibody targeting CD37, a tetraspanin protein highly expressed on B cells and B-cell malignancies, conjugated to the potent cytotoxic maytansinoid DM1 via a cleavable linker. Upon binding to CD37 on the surface of tumor cells, the ADC is internalized, and DM1 is released intracellularly, where it disrupts microtubule assembly, leading to cell cycle arrest and apoptosis. It has been clinically evaluated for the treatment of relapsed or refractory B-cell non-Hodgkin lymphoma (NHL), including diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma.