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Updated: Jan 15, 2026
Identification of Mediators of T-cell Receptor Signaling via the Screening of Chemical Inhibitor Libraries
Published on: January 22, 2019
Design and validation of the first-in-class PROTACs for targeted degradation of the immune checkpoint LAG-3
Nelson García Vázquez1, Somaya A Abdel-Rahman2, Hossam Nada1
1Department of Radiology, Molecular Imaging Innovations Institute (MI3), Weill Cornell Medicine, New York, NY 10065, USA.
Abstract:
Lymphocyte activation gene-3 (LAG-3) is an inhibitory immune checkpoint receptor that plays a central role in T cell exhaustion and immune evasion in cancer. While monoclonal antibodies targeting LAG-3 have entered clinical development, small molecule approaches remain largely unexplored. Here, we report the design and validation of the first-in-class PROTACs for targeted degradation of LAG-3. In this study, we repurposed a LAG-3-binding small molecule identified through DNA-encoded library (DEL) screening as the targeting ligand for a series of CRL4CRBN-based PROTACs designed with varied linker lengths. Western blot analysis in Raji-LAG3 cells demonstrated that LAG-3 PROTAC-1 and LAG-3 PROTAC-3 induce potent, dose-dependent degradation of LAG-3, with DC50 values of 0.27 μM and 0.42 μM, respectively. Molecular docking and molecular dynamics (MD) simulations revealed the LAG-3 binding mode of designed PROTACs and provided structural insights into PROTAC-mediated ternary complex formation. Collectively, this work establishes a proof-of-concept for chemical degradation of LAG-3 for the first time and paves the way for novel immunotherapeutic strategies.
Insights
Researchers developed the first Proteolysis-Targeting Chimeras (PROTACs) to degrade Lymphocyte-activation gene-3 (LAG-3). This novel small molecule approach effectively targets LAG-3, offering new possibilities for cancer immunotherapy.
Area of Science:
- Immunology
- Oncology
- Medicinal Chemistry
Background:
- Lymphocyte-activation gene-3 (LAG-3) is an inhibitory immune checkpoint receptor crucial for T cell exhaustion and cancer immune evasion.
- Current therapeutic strategies primarily involve monoclonal antibodies, leaving small molecule approaches underexplored.
Purpose of the Study:
- To design and validate the first Proteolysis-Targeting Chimeras (PROTACs) for the targeted degradation of LAG-3.
- To establish a proof-of-concept for small molecule-mediated chemical degradation of LAG-3.
Main Methods:
- Repurposing a DNA-encoded library (DEL)-identified LAG-3-binding small molecule as a targeting ligand.
- Synthesizing a series of CRL4CRBN-based PROTACs with varying linker lengths.
- Utilizing Western blot analysis, molecular docking, and molecular dynamics simulations for validation and mechanistic insights.
Main Results:
- Demonstrated potent and dose-dependent degradation of LAG-3 in Raji-LAG3 cells using LAG-3 PROTAC-1 and LAG-3 PROTAC-3 (DC50 values of 0.27 μM and 0.42 μM, respectively).
- Provided structural insights into PROTAC binding and ternary complex formation through computational simulations.
Conclusions:
- Established the first-in-class PROTACs for targeted LAG-3 degradation, validating a novel small molecule strategy.
- This work lays the foundation for developing new immunotherapeutic approaches targeting LAG-3.
