Identification and Validation of New Interleukin-2 Ligands Using DNA-Encoded Libraries

Area of Science:

• Immunology
• Molecular Biology
• Medicinal Chemistry

Background:

• Interleukin-2 (IL2) is a critical pro-inflammatory cytokine for immune responses, with expanding therapeutic applications.
• Current IL2 therapeutics face challenges due to binding with CD25, a marker on immunosuppressive regulatory T cells (Tregs).
• Developing IL2-based drugs that spare Tregs is a key goal in immunotherapy.

Purpose of the Study:

• To identify novel IL2 ligands that do not bind to the CD25 receptor.
• To explore new avenues for IL2-based therapeutic development by creating Treg-sparing molecules.
• To discover small-molecule modulators of IL2 activity with potential therapeutic benefits.

Main Methods:

• Screening of a large DNA-encoded library (669,240 members) to identify IL2-binding compounds.
• Medicinal chemistry optimization of identified IL2 ligands.
• Biochemical characterization, including dissociation constant (Kd) determination and size-exclusion chromatography.
• Competitive binding assays using the NARA1 antibody to assess CD25 recognition.

Main Results:

• A novel series of IL2 ligands was discovered from the DNA-encoded library.
• Compound 18 demonstrated potent binding to IL2 (Kd = 0.34 μM) and formed a kinetically stable complex.
• Compound 18 was confirmed to recognize the CD25-binding site, indicating potential for Treg interaction.

Conclusions:

• Compound 18 and related molecules represent promising starting points for developing novel IL2 modulators.
• These compounds may enable the design of IL2-based therapeutics that selectively target desired immune cells while sparing Tregs.
• The findings open new possibilities for precise immunomodulation in various diseases.