BACKGROUND: Targeting of cytokines into the tumor sites using antibody-cytokine fission proteins represents a novel approach in cancer immunotherapy. We previously reported a novel monoclonal antibody, FU-MK-1, which recognizes a glycoprotein antigen (termed MK-1 antigen) that is overexpressed on the surface of a majority of carcinomas. MATERIALS AND METHODS: To target IL-2 and cytotoxicity of effector cells to MK-1-expressing tumor cells, we genetically fused recombinant human interleukin-2 (rhIL-2) to a single chain variable fragment (scFv) antibody derived from FU-MK-1. The resulting fission protein, designated FUscFv/IL-2 was expressed in Pichia pastoris, purified by Ni-affinity chromatography, and characterized for the MK-1-binding specificity and the IL-2 biological activity. RESULTS: The FUscFv/IL-2 fusion protein effectively introduced a specific cytotoxicity of lymphokine-activated killer cells to the tumor cells and consequently suppressed the tumor growth in a SCID mouse xenograft model. CONCLUSION: This approach may be used for in vivo administration to localize IL-2 to tumor tissues, enhancing the immune response to human MK-1-expressing tumors while reducing systemic side-effects.
BACKGROUND: Targeting of cytokines into the tumor sites using antibody-cytokine fission proteins represents a novel approach in cancer immunotherapy. We previously reported a novel monoclonal antibody, FU-MK-1, which recognizes a glycoprotein antigen (termed MK-1 antigen) that is overexpressed on the surface of a majority of carcinomas. MATERIALS AND METHODS: To target IL-2 and cytotoxicity of effector cells to MK-1-expressing tumor cells, we genetically fused recombinant humaninterleukin-2 (rhIL-2) to a single chain variable fragment (scFv) antibody derived from FU-MK-1. The resulting fission protein, designated FUscFv/IL-2 was expressed in Pichia pastoris, purified by Ni-affinity chromatography, and characterized for the MK-1-binding specificity and the IL-2 biological activity. RESULTS: The FUscFv/IL-2 fusion protein effectively introduced a specific cytotoxicity of lymphokine-activated killer cells to the tumor cells and consequently suppressed the tumor growth in a SCIDmouse xenograft model. CONCLUSION: This approach may be used for in vivo administration to localize IL-2 to tumor tissues, enhancing the immune response to humanMK-1-expressing tumors while reducing systemic side-effects.