Novel cytokine–antibody fusion protein, N-820, to enhance the functions of ex vivo expanded natural killer cells against Burkitt lymphoma

BackgroundThe prognosis of patients with relapsed or progressive B cell (CD20+) non-Hodgkin’s lymphoma (B-NHL), including Burkitt lymphoma (BL), is dismal due to chemoradiotherapy resistance. Novel therapeutic strategies are urgently needed. N-820 is a fusion protein of N-803 (formerly known as ALT-803) to four single-chains of rituximab. This agent has tri-specific binding activity to CD20 and enhanced antibody-dependent cell-mediated cytotoxicity.MethodsWe investigated the anti-tumor combinatorial effects of N-820 with ex vivo expanded peripheral blood natural killer (exPBNK) cells against rituximab-sensitive and rituximab-resistant CD20+ BL in vitro using cytoxicity assays and in vivo using human BL xenografted NOD/SCID/IL2rγnull (NSG) mice. We also investigated the cytokines/chemokines/growth factors released using ELISA and multiplex assay. Gene expression changes were examined using real-time PCR arrays.ResultsN-820 significantly enhanced the expression of NK activating receptors (p