Engineered ipilimumab variants that bind human and mouse CTLA-4
Testing of candidate monoclonal antibody therapeutics in preclinical models is an essential step in drug development. Identification of antibody therapeutic candidates that bind their human targets and cross-react to mouse orthologs is often challenging, especially for targets with low sequence homo...
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Taylor & Francis Group
2025-12-01
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| Series: | mAbs |
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| Online Access: | https://www.tandfonline.com/doi/10.1080/19420862.2025.2451296 |
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| author | Brett Robison SJ Diong Anusha Kumar Thomas M. Moon Olin Chang Bryant Chau Christine Bee Ishita Barman Arvind Rajpal Alan J. Korman Sean West Pavel Strop Peter S. Lee |
| author_facet | Brett Robison SJ Diong Anusha Kumar Thomas M. Moon Olin Chang Bryant Chau Christine Bee Ishita Barman Arvind Rajpal Alan J. Korman Sean West Pavel Strop Peter S. Lee |
| author_sort | Brett Robison |
| collection | DOAJ |
| description | Testing of candidate monoclonal antibody therapeutics in preclinical models is an essential step in drug development. Identification of antibody therapeutic candidates that bind their human targets and cross-react to mouse orthologs is often challenging, especially for targets with low sequence homology. In such cases, surrogate antibodies that bind mouse orthologs must be used. The antibody 9D9, which binds mouse CTLA-4, is a commonly used surrogate for CTLA-4 checkpoint blockade studies in mouse cancer models. In this work, we reveal that 9D9 has significant biophysical dissimilarities to therapeutic CTLA-4 antibodies. The 9D9-mCTLA4 complex crystal structure was determined and shows that the surrogate antibody binds an epitope distinct from ipilimumab and tremelimumab. In addition, while ipilimumab has pH-independent binding to hCTLA-4, 9D9 loses binding to mCTLA-4 at physiologically relevant acidic pH ranges. We used phage and yeast display to engineer ipilimumab to bind mouse CTLA-4 with single-digit nM affinity from an initial state with no apparent binding. The engineered variants showed pH-independent and cross-reactive binding to both mouse and human CTLA-4. Crystal structures of a variant in complex with both mouse and human CTLA-4 confirmed that it targets an equivalent epitope as ipilimumab. These cross-reactive ipilimumab variants may facilitate improved translatability and future mechanism-of-action studies for anti-CTLA-4 targeting in murine models. |
| format | Article |
| id | doaj-art-ba91904abd2f4989b4fb707da30b86e6 |
| institution | Kabale University |
| issn | 1942-0862 1942-0870 |
| language | English |
| publishDate | 2025-12-01 |
| publisher | Taylor & Francis Group |
| record_format | Article |
| series | mAbs |
| spelling | doaj-art-ba91904abd2f4989b4fb707da30b86e62025-01-31T12:34:05ZengTaylor & Francis GroupmAbs1942-08621942-08702025-12-0117110.1080/19420862.2025.2451296Engineered ipilimumab variants that bind human and mouse CTLA-4Brett Robison0SJ Diong1Anusha Kumar2Thomas M. Moon3Olin Chang4Bryant Chau5Christine Bee6Ishita Barman7Arvind Rajpal8Alan J. Korman9Sean West10Pavel Strop11Peter S. Lee12Discovery Biotherapeutics, Bristol Myers Squibb, Redwood City, CA, USADiscovery Biotherapeutics, Bristol Myers Squibb, Redwood City, CA, USADiscovery Biotherapeutics, Bristol Myers Squibb, Redwood City, CA, USADiscovery Biotherapeutics, Bristol Myers Squibb, Redwood City, CA, USADiscovery Biotherapeutics, Bristol Myers Squibb, Redwood City, CA, USALarge Molecule Drug Discovery, Genentech, Research and Early Development, South San Francisco, CA, USABiochemistry and Biophysics, Merck, South San Francisco, CA, USAProtein and Antibody Portfolio, Genscript, South San Francisco, CA, USAResearch, Xaira Therapeutics, Brisbane, CA, USAResearch, Vir Biotechnology, San Francisco, CA, USADiscovery Biotherapeutics, Bristol Myers Squibb, Redwood City, CA, USAResearch, Tallac Therapeutics, Burlingame, CA, USABiotherapeutics and Genetic Medicine, AbbVie, South San Francisco, CA, USATesting of candidate monoclonal antibody therapeutics in preclinical models is an essential step in drug development. Identification of antibody therapeutic candidates that bind their human targets and cross-react to mouse orthologs is often challenging, especially for targets with low sequence homology. In such cases, surrogate antibodies that bind mouse orthologs must be used. The antibody 9D9, which binds mouse CTLA-4, is a commonly used surrogate for CTLA-4 checkpoint blockade studies in mouse cancer models. In this work, we reveal that 9D9 has significant biophysical dissimilarities to therapeutic CTLA-4 antibodies. The 9D9-mCTLA4 complex crystal structure was determined and shows that the surrogate antibody binds an epitope distinct from ipilimumab and tremelimumab. In addition, while ipilimumab has pH-independent binding to hCTLA-4, 9D9 loses binding to mCTLA-4 at physiologically relevant acidic pH ranges. We used phage and yeast display to engineer ipilimumab to bind mouse CTLA-4 with single-digit nM affinity from an initial state with no apparent binding. The engineered variants showed pH-independent and cross-reactive binding to both mouse and human CTLA-4. Crystal structures of a variant in complex with both mouse and human CTLA-4 confirmed that it targets an equivalent epitope as ipilimumab. These cross-reactive ipilimumab variants may facilitate improved translatability and future mechanism-of-action studies for anti-CTLA-4 targeting in murine models.https://www.tandfonline.com/doi/10.1080/19420862.2025.2451296Antibody engineeringCTLA-4immune checkpointphage displayspecies cross reactivityyeast display |
| spellingShingle | Brett Robison SJ Diong Anusha Kumar Thomas M. Moon Olin Chang Bryant Chau Christine Bee Ishita Barman Arvind Rajpal Alan J. Korman Sean West Pavel Strop Peter S. Lee Engineered ipilimumab variants that bind human and mouse CTLA-4 mAbs Antibody engineering CTLA-4 immune checkpoint phage display species cross reactivity yeast display |
| title | Engineered ipilimumab variants that bind human and mouse CTLA-4 |
| title_full | Engineered ipilimumab variants that bind human and mouse CTLA-4 |
| title_fullStr | Engineered ipilimumab variants that bind human and mouse CTLA-4 |
| title_full_unstemmed | Engineered ipilimumab variants that bind human and mouse CTLA-4 |
| title_short | Engineered ipilimumab variants that bind human and mouse CTLA-4 |
| title_sort | engineered ipilimumab variants that bind human and mouse ctla 4 |
| topic | Antibody engineering CTLA-4 immune checkpoint phage display species cross reactivity yeast display |
| url | https://www.tandfonline.com/doi/10.1080/19420862.2025.2451296 |
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