Engineering a Single-Agent Cytokine/Antibody Fusion That Selectively Expands Regulatory T Cells for Autoimmune Disease Therapy

Abstract

IL-2 has been used to treat diseases ranging from cancer to autoimmune disorders, but its concurrent immunostimulatory and immunosuppressive effects hinder efficacy. IL-2 orchestrates immune cell function through activation of a high-affinity heterotrimeric receptor (composed of IL-2Rα, IL-2Rβ, and common γ [γ]). IL-2Rα, which is highly expressed on regulatory T (T) cells, regulates IL-2 sensitivity. Previous studies have shown that complexation of IL-2 with the JES6-1 Ab preferentially biases cytokine activity toward T cells through a unique mechanism whereby IL-2 is exchanged from the Ab to IL-2Rα. However, clinical adoption of a mixed Ab/cytokine complex regimen is limited by stoichiometry and stability concerns. In this study, through structure-guided design, we engineered a single agent fusion of the IL-2 cytokine and JES6-1 Ab that, despite being covalently linked, preserves IL-2 exchange, selectively stimulating T expansion and exhibiting superior disease control to the mixed IL-2/JES6-1 complex in a mouse colitis model. These studies provide an engineering blueprint for resolving a major barrier to the implementation of functionally similar IL-2/Ab complexes for treatment of human disease.

Dynamic changes in the regulatory T-cell heterogeneity and function by murine IL-2 mutein

“…Additional efforts have focused on novel forms of IL2 with superior pharmacokinetics and Treg selectivity. These include a long-lived bivalent IgG-human IL2 fusion protein with N88D mutation that reduces IL2Rβ binding (Peterson et al, 2018), a polyethylene glycol (PEG)-modified murine IL2 that increases IL2 retention in the body by protection from enzymatic digestion and renal clearance (Wu et al, 2016), and a murine IL2/anti-IL2 antibody (JES6-1) conjugate (Spangler et al, 2018). Despite the effort to develop various forms of IL2 with superior pharmacokinetics and selectivity for treatment of autoimmune and inflammatory diseases, it is not clear how they affect heterogeneity of Tregs, given that Tregs exists in a variety of sub-states at different tissue sites, which are phenotypically and functionally heterogeneous.…”

Mechanisms of human FoxP3+ Treg cell development and function in health and disease

“…One example is IL‐2/CD25 fusion proteins, where IL‐2 is bound to CD25 by a non‐cleavable linker to increase the persistence of IL‐2 and reduce binding to the intermediate‐affinity IL‐2R . Another investigated compound is IL‐2‐anti‐IL‐2 monoclonal antibody immune complexes (IL‐2IC) , where IL ‐ 2 is bound to the IL‐2IC antibody such that the CD25‐binding epitope is exposed and the CD122 (IL‐2Rβ)‐binding epitope is blocked (e.g. clone JES6‐1), preferentially inducing the expansion of T reg cells over T conv cells.…”

Engineering IL-2 to Give New Life to T Cell Immunotherapy

“…The anti-IL-2 mAb JES6 prolonged the half-life of IL-2 (30), while also blocking the interaction of IL-2 with IL-2Rβ, leading to increased Treg proliferation since binding to the high-affinity IL-2Rαβγ c was preserved (29). However, until now, clinical adoption of antibody/cytokine complexes has been limited by difficulties in manufacturing them and maintaining their stability (31).…”