Protein ULBP2-BB4 has anti-tumor effect

A novel bispecific protein (ULBP2-BB4) targeting the NKG2D receptor on natural killer (NK) cells has potent antitumor activity against human multiple myeloma in vitro and in vivo

Department of Internal Medicine, Laboratory of Immunotherapy, University Hospital, Cologne, Germany

The inability of the immune system to recognize and kill malignant plasma cells in patients with multiple myeloma (MM) has been attributed in part to the ineffective activation of natural killer (NK) cells. In order to activate and target NK cells to the malignant cells in MM we designed a novel recombinant bispecific protein (ULBP2-BB4). While ULBP2 binds the activating NK receptor NKG2D, the BB4 moiety binds to CD138, which is overexpressed on a variety of malignancies including MM. ULBP2-BB4 strongly activated primary NK cells as demonstrated by a significant increase in IFN-g secretion. In vitro, ULBP2-BB4 enhanced the NK-mediated lysis of two CD138+ human multiple myeloma cell lines, U-266 and RPMI-8226, and of primary malignant plasma cells in the allogenic and autologous setting. Moreover, in a nude mouse model with subcutaneously growing RPMI-8226 cells, the co-therapy with ULBP-BB4 and human peripheral blood lymphocytes abrogated the tumor growth. These data suggest potential clinical use of this novel construct in patients with MM. The use of recombinant NK receptor ligands that target NK cells to tumor cells might offer new approaches for other malignancies provided a tumor antigen-specific antibody is available.

Elke Pogge von Strandmann, Hinrich P. Hansen, Katrin S. Reiners, Roland Schnell, Peter Borchmann, Sabine Merkert, Venkateswara R. Simhadri, Andreas Draube, Marcel Reiser, Ingvill Purr, Michael Hallek, and Andreas Engert