Identification of a potent anti‐IL‐15 antibody with opposing mechanisms of action in vitro and in vivo

Abstract

BACKGROUND AND PURPOSE ) is important in the activation and proliferation of lymphocytic cell populations and is implicated in inflammatory disease. We report the characterization of a novel monoclonal antibody DISC0280 which is specific for human IL-15. EXPERIMENTAL APPROACHDISC0280 was characterized in a direct binding assay of IL-15 with IL-15 receptor a (IL-15Ra) and by its ability to alter IL-15 mediated proliferation of a range of cell lines (cytotoxic T lymphocyte line-2, M-07e, KIT225). A pharmacodynamic model injecting male C57/BL6 mice with IL-15 or IL-15/IL-15Ra, with or without DISC0280, and assessing changes in lymphocytic cell populations and serum cytokines was utilized. KEY RESULTSDISC0280 inhibited the binding of IL-15 to IL-15Ra and also potently inhibits IL-15 dependent proliferation of cells expressing IL-15Ra, shared interleukin 2/ interleukin 15 receptor b chain (IL-15Rb) and common gamma chain (gc). DISC0280 also inhibited the IL-15 dependent proliferation of M-07e cells that only express IL-15Rb/gc subunits. Human IL-15 injected into mice caused an increase in NK1.1 + and CD3 + cells in the spleen and peripheral blood and these effects were unexpectedly potentiated by giving DISC0280 with human IL-15. This increase in cells caused by DISC0280/IL-15 co-administration was greater than that observed when IL-15 was administered complexed with soluble IL-15Ra. CONCLUSIONS AND IMPLICATIONSThe ability of DISC0280 to bind to the IL-15Ra-binding site on IL-15 allows trans-presentation of IL-15 by DISC0280 in vivo, similar to the trans-presentation by soluble IL-15Ra. DISC0280 may be therefore suitable as a clinical substitute for IL-15. Abbreviationsgc, common g chain; hIL-15, human IL-15; hIL-15/sIL-15Ra, pre-associated complex of human IL-15 and soluble IL-15Ra; IL-2, interleukin 2; (s)IL-15Ra, (soluble)interleukin 15 receptor a; IL-15Rb, shared interleukin 2/ interleukin 15 receptor b chain

Discovery and characterization of a novel humanized anti-IL-15 antibody and its relevance for the treatment of refractory celiac disease and eosinophilic esophagitis

“…27 Using single amino-acid substitution, residues found to be most essential for the binding of CALY-002 to IL-15 were D109, E112, I116 and N119. However, in contrast with what was proposed for the originator B-E29 antibody, 27,26 we found that CALY-002 did not prevent binding of IL-15 to IL-15Ra in an in vitro binding assay using biotinylated IL-15 as described previously (Fig. 1A).…”

“…1A). 26 Indeed, since the quaternary structure of IL-15 in complex with IL-15Rabg was resolved, it was possible to visualize the epitope recognized by CALY-002 within this complex ( Fig. 1B).…”

“…8,9 This might be related to the fact that IL-15 has been an elusive and difficult target for the development of potent and fully in vivo active neutralizing antibodies. 26,27 We describe herein the discovery and characterization of CALY-002, a best-in-class neutralizing antibody against IL-15, and provide data supporting its relevance for the treatment of RCD and EoE.…”

“…Since IL-15 enhances proliferation and survival of a variety of cell lines, 26,27 effects of various concentrations of CALY-002 were tested on cell survival/proliferation induced by recombinant IL-15, and CALY-002 potency measured as its half-maximum inhibitory concentration (IC 50 ). Two different cell lines were tested.…”

Engineering a High-Affinity Anti-IL-15 Antibody: Crystal Structure Reveals an α-Helix in VH CDR3 as Key Component of Paratope

“…5), but is also proximal to the regions thought to be involved in β and γ receptor binding, 20,21 suggesting that a more complex interaction with the three receptors could in part be responsible for this increase in potency. We have recently reported the ability of DISC0280 to neutralise IL-15 in an alternative cell line that expresses only β and γ receptor subunits, 30 indicating that the antibody not only inhibits the binding of IL-15 to the IL-15 α-receptor subunit but also is capable of blocking the signalling of IL-15 through these subunits.…”