A novel humanized monoclonal antibody, 2D4, targeting CD132 (also known as the common gamma chain, γc), has shown promising results in preclinical studies for the treatment of systemic lupus erythematosus (SLE). The research, published in Nature, highlights 2D4's ability to selectively inhibit IL-21 while exhibiting weaker blocking activity against IL-2, potentially offering a more targeted therapeutic approach compared to broader CD132 inhibitors.
CD132 and SLE Pathogenesis
CD132 is a component of several cytokine receptors, including those for IL-2, IL-7, IL-15, and IL-21. Elevated CD132 signaling in lymphocytes of SLE patients contributes to pro-inflammatory responses. Studies have shown a significant upregulation of CD132 expression across almost all lymphocyte subtypes, including CD3+ T cells and CD19+ B cells, in SLE patients. The expression of CD132 was significantly and positively correlated with SLEDAI scores in CD3+ T, CD4+ T, CD19+ B and plasma cells.
2D4: A Selective IL-21 Antagonist
Researchers aimed to identify an anti-huCD132 with a superior IL-21 blocking activity but weaker IL-2 blocking activity than REGN7257. Initial screening identified 2D4, which demonstrated comparable IL-21 blocking to REGN7257 but significantly weaker IL-2 blocking activity. Further analysis revealed that 2D4 had a >2-fold lower median inhibition concentration (IC50) value relative to REGN7257 in blocking IL-21. In natural NK92 cells, 2D4 had a 10-fold better IC50 value in blocking IL-21 activity relative to REGN7257.
Cryo-electron microscopy revealed that 2D4 binds to a distinct site on the CD132 D1 domain compared to REGN7257, resulting in reduced spatial hindrance with IL-2. This structural difference correlates with the functional assay results, where the inhibitory effect of 2D4 on IL-2 was not as potent as that of REGN7257.
In Vivo Efficacy and Immunomodulatory Effects
In vivo studies using humanized CD132 mice (CD132hu/hu) demonstrated that 2D4 effectively suppressed T and B cell populations without significantly affecting the proportion of regulatory T cells (Tregs). This is particularly important, as Tregs play a crucial role in maintaining immune tolerance in SLE patients. A pharmacodynamic study in CD132hu/hu mice showed a significant reduction in leukocyte counts, including T-lymphocytes and subtypes, B-lymphocytes, and NK-cells.
Furthermore, 2D4 inhibited T cell-dependent, antigen-specific B-cell responses in germinal centers. In mice challenged with keyhole limpet hemocyanin (KLH), 2D4 fully inhibited KLH-specific IgG1 production. Consistent with the reduction of antigen-specific immunoglobulins, germinal center (GC) response was efficiently reduced by 2D4, evident in the increased numbers of naive B cells and decreased accumulation of GC B cells in drainage lymph nodes (dLNs) of the 2D4 group.
Protection Against Lupus Nephritis
In a pristane-induced mouse model of lupus, 2D4 treatment significantly reduced levels of anti-dsDNA antibodies and pro-inflammatory cytokines, while preserving anti-inflammatory cytokines. The urinary albumin to creatinine ratio (Alb/cre), a reliable indicator of kidney function, was significantly lower in 2D4-treated mice. Histological analyses revealed less pronounced glomerular changes in the 2D4-treated group. 2D4 also reduced renal IgG1 deposits.
Superiority Over Belimumab in Lupus Nephritis Model
Compared to Belimumab, a B-cell-targeted therapy approved for SLE, 2D4 demonstrated enhanced efficacy in a lupus nephritis mouse model. 2D4 significantly inhibited the elevation of the urinary Alb/cre, while Belimumab did not affect these factors. 2D4 was also effective in reducing circulating T cells, including CD4+ and CD8+ T cells, which were not affected by Belimumab. These results suggest that 2D4's dual targeting of T and B cells may provide a more effective therapeutic strategy for SLE.
Ex Vivo and In Vivo Studies with SLE Patient Samples
Ex vivo studies using PBMCs from SLE patients showed that 2D4 significantly inhibited the secretion of IgG1, IgG2, IgG3, and IGA. The addition of 2D4 significantly suppressed the release of IFN-γ, TNF-a, IL-17A and IL-5 by PBMCs from SLE patients. In a humanized lupus-like mouse model (GVHD) generated by transferring PBMCs from SLE patients to NOD-SCID mice, 2D4 treatment reduced human-derived inflammatory factors and anti-dsDNA-IgG levels, and protected against renal damage.
These findings suggest that 2D4 holds significant promise as a novel therapeutic agent for SLE, offering a potentially more targeted and effective approach compared to existing therapies.
