Daratumumab (DARA) is a human monoclonal IgG1κ CD38-targeting antibody that functions through several mechanisms of action (MOA), including CDC, ADCC, ADCP and induction of apoptosis. An additional, novel role of immune modulation and increased adaptive immune response was revealed from translational studies of DARA (16 mg/kg) in single-agent, phase 1/2 studies (SIRIUS [MMY2002] and GEN501; Krejcik J et al, Blood 2016;128:384-94). To further explore the ability of DARA to promote adaptive T-cell responses, we profiled T-cell repertoires (TCR) to evaluate T-cell clonality, expansion, and diversity from samples collected in POLLUX (MMY3003), a phase 3, randomized, open-label, multicenter study for patients with relapsed/refractory MM, in which DARA was tested in combination with lenalidomide plus dexamethasone versus lenalidomide plus dexamethasone alone (DRd vs. Rd; Dimopoulos MA et al, N Engl J Med 2016; in press).