Pts with a lower number of KIR/HLA interactions appeared to have a consistently better outcome across a number of efficacy parameters when treated with anti-CD20 antibodies; the strongest effect was observed in the G-Clb arm. These findings warrant investigation of combined KIR-blockade with anti-CD20 antibody treatment in pts with CLL to decrease the impact of these inhibitory interactions on antibody-dependent cell-mediated cytotoxicity.