CD37 and lymphoma: Naratuximab emtansine is an ADC that incorporates a humanized IgG1 anti-CD37 monoclonal Ab conjugated to the maytansinoid DM1 via the thioether linker, N-succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC), with proven preclinical anti-lymphoma activity (Table 2) [161, 162].