Enhancement of Rituximab-induced cell death by the physical association of CD20 with CD40 molecules on the cell surface

Abstract

CD20 is an attractive therapeutic target given the success of its monoclonal antibody, Rituximab, in the treatment of B-cell malignancies and B-cell-mediated autoimmune diseases. Treatment with Rituximab causes a rapid depletion of B cells and a decrease in disease symptoms. Despite the clinical efficiency of Rituximab, its mechanism of action is not completely understood. In this study, we aimed at further investigating the Rituximab-induced cell death and the factors affecting such responses. Our results indicate that Rituximab-induced cell death depends on the nature of the cells and levels of CD20 expression on the cell surface. Coexpression of CD20 with CD40, a member of the TNF receptor family that is known to be physically associated with CD20 on the cell surface, enhances the apoptotic response induced by Rituximab. Inhibiting the formation of CD40 disulfide-bound-homodimers, a process required for some CD40 signaling, further enhances Rituximab-induced cell death. Cell death induced by anti-CD40 mAb is also upregulated by the presence of CD20, suggesting a bidirectional influence of the CD20/CD40 association. Moreover, treating cells with both anti-CD20 and anti-CD40 antibodies improves the cell death response induced by a single-agent treatment. These results highlight the role of the CD20/CD40 association in triggering B-cell depletion and may pave the way for an alternative more efficient therapeutic strategy in treating B-cell-mediated disorders.

Drug-free macromolecular therapeutics – a new paradigm in polymeric nanomedicines

“…, CD20/CD40, 162 CD20/FGFR3, 163 CD37/CD20 or CD37/CD19 152 ), and designed as a switch for ON-OFF regulation of cellular events. 158,164 …”

Role of CD154 in cancer pathogenesis and immunotherapy

“…Interestingly, a physical and functional association has been recently reported between CD40 and CD20 on cell surface, leading to upregulated CD20-and CD40-mediated cell death responses upon stimulation with their respective antibodies. Data also demonstrated an additive effect of both anti-CD20 and anti-CD40 antibodies in inducing cell death [112]. These findings are very promising in terms of developing a combination therapeutic strategy with anti-CD40 and anti-CD20 mAbs.…”

B cell Therapy to Treat an Axonal Neuropathy in Mixed Connective Tissue Disease

“…Three molecular features of CD20 made it an attractive choice for immunotherapy: (A) it does not internalize upon monoclonal antibody (mAb) binding; (B) it is not shed from the cell surface; (C) the physical association between CD20 and CD40 on the B cell surface enhances cell death [2,3]. Rituximab targets CD20 and if anti-CD40 mAb is added in the laboratory (not yet clinically available) additional cell death is noted [3]. B cells are not simply passive recipients of signals necessary for their differentiation into antibody-producing plasma cells.…”

“…Work has already identified B cell surface markers other than CD20 that may be targeted to improve the response. We know that treating B cells with both anti-CD20 and anti-CD40 antibodies together enhances the apoptotic response induced by a single dose of rituximab and is a more efficient therapeutic strategy for treating B cell-mediated disorders [3]. An antibody against another B cell marker, CD19, appears to remove a broader range of B cell populations, indicating that anti-CD19 antibody therapy may be more effective in some diseases.…”

“…Rituximab binds to CD20, which is almost exclusively expressed on human B cells [3,4]. Other mAbs that target B cells are in phase III of clinical development.…”