IgG-Based Bispecific Anti-CD95 Antibodies for the Treatment of B Cell-Derived Malignancies and Autoimmune Diseases

SIMPLE SUMMARY: Therapeutic antibodies have become a crucial cornerstone of the standard therapy for lymphoma and autoimmune diseases. However, the respective target antigens are also expressed on healthy B cells resulting in unspecific effects. In this article, we present a novel approach to selectively induce apoptosis in lymphoma cells and autoreactive B cells that express the CD95 death receptor. Therefore, we developed an improved IgG-based bispecific antibody format with favorable production properties and pharmacokinetics for CD20- and CD19-directed induction of apoptosis via CD95. We could show that our bispecific anti-CD95 antibodies are very efficient in the depletion of malignant and autoreactive B cells in vitro and in vivo. Therefore, our antibodies could help to provide a more selective therapy for patients with B cell-derived malignancies and autoimmune diseases. ABSTRACT: Antibodies against the B cell-specific antigens CD20 and CD19 have markedly improved the treatment of B cell-derived lymphoma and autoimmune diseases by depleting malignant and autoreactive B cells. However, since CD20 and CD19 are also expressed on healthy B cells, such antibodies lack disease specificity. Here, we optimize a previously developed concept that uses bispecific antibodies to induce apoptosis selectively in malignant and autoreactive B cells that express the death receptor CD95. We describe the development and characterization of bispecific antibodies with CD95xCD20 and CD95xCD19 specificity in a new IgG-based format. We could show that especially the CD95xCD20 antibody mediated a strong induction of apoptosis in malignant B cells in vitro. In vivo, the antibody was clearly superior to the previously used Fabsc format with identical specificities. In addition, both IgGsc antibodies depleted activated B cells in vitro, leading to a significant reduction in antibody production and cytokine secretion. The killing of resting B cells and hepatocytes that lack CD95 and CD20/CD19, respectively, was marginal. Thus, our results imply that bispecific anti-CD95 antibodies in the IgGsc format are an attractive tool for a more selective and efficient depletion of malignant as well as autoreactive B cells.