Structural insights into an immune checkpoint receptor reveal a novel approach to cancer immunotherapy
Abstract/Contents
- Abstract
- Immunotherapy has revolutionized cancer treatment, but the limited response rates to current checkpoint inhibitors necessitate the identification of additional immunotherapeutic approaches. Lymphocyte-activation gene 3 (LAG-3) has emerged as a potential orthogonal checkpoint molecule that negatively regulates T cell activation. First-generation monoclonal antibodies against LAG-3 demonstrated moderate success, despite a lack of knowledge about the mechanism by which LAG-3 functions. This thesis aims to provide key details focused on LAG3 structural characterization, including functional consequences of LAG-3 dimerization on ligand binding and activation, as well as epitope mapping of murine and clinical human LAG-3 antibodies. The first major accomplishment of this work was the elucidation of the crystal structure of the glycosylated mouse LAG-3 extracellular domain, providing valuable insights into its overall architecture and molecular features. This structural information, which was generated in collaboration with Irimpan Mathews at SLAC, served as a foundation for further investigations into the functional aspects of LAG-3. By employing sophisticated biochemical and biophysical techniques in collaborative work with the laboratories of Jun Wang and Xiang-Peng Kong at NYU, we demonstrated that disruption of D2 domain dimerization severely compromised LAG-3's ability to engage with its ligands and modulate T-cell responses. To further explore the potential therapeutic implications of disrupting LAG-3 dimerization, we performed fine epitope mapping of an antibody called C9B7W, known to bind the LAG-3 D2 domain that we identified as being key to LAG-3 dimerization. The study pinpointed the binding site of C9B7W squarely at the D2 dimerization interface, suggesting a potential mechanism by which this antibody disrupts LAG-3 function. Epitope mapping and electron microscopy showed that like C9B7W, murine antibodies which bind LAG-3 D1 and D3 can also disrupt dimerization and ligand binding. Lastly, we undertook a comprehensive epitope mapping analysis of 11 currently known human LAG-3 antibodies under clinical development. Intriguingly, unlike C9B7W, none of the LAG-3 antibodies under clinical development bound to the D2 dimerization interface, and all bound to the LAG-3 D1 domain, some with overlapping and others with disparate epitopes. Collectively, these findings significantly contribute to our understanding of LAG-3 biology and provide crucial insights into its therapeutic potential. The structural characterization, identification of the critical role of D2 dimerization, and epitope mapping of disruptive and clinical human LAG-3 antibodies pave the way for the development of novel immunotherapeutic strategies targeting LAG-3 in the fight against cancer and other immune-related diseases.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2023; ©2023 |
| Publication date | 2023; 2023 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Silberstein, John Louis |
|---|---|
| Degree supervisor | Cochran, Jennifer |
| Thesis advisor | Cochran, Jennifer |
| Thesis advisor | Huang, Possu |
| Thesis advisor | Mellins, Elizabeth |
| Thesis advisor | Robinson, Bill |
| Degree committee member | Huang, Possu |
| Degree committee member | Mellins, Elizabeth |
| Degree committee member | Robinson, Bill |
| Associated with | Stanford University, School of Medicine |
| Associated with | Stanford University, Department of Microbiology and Immunology |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | John Louis Silberstein. |
|---|---|
| Note | Submitted to the Department of Microbiology and Immunology. |
| Thesis | Thesis Ph.D. Stanford University 2023. |
| Location | https://purl.stanford.edu/kn512tb1251 |
Access conditions
- Copyright
- © 2023 by John Louis Silberstein
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
Also listed in
Loading usage metrics...