FcgRIIB is an immune checkpoint limiting the activity of Treg-targeting antibodies in the tumor microenvironment Journal Article
| Authors: | Knorr, D. A.; Blanchard, L.; Leidner, R. S.; Jensen, S. M.; Meng, R.; Jones, A.; Ballesteros-Merino, C.; Bell, R. B.; Baez, M.; Marino, A.; Sprott, D.; Bifulco, C. B.; Piening, B.; Dahan, R.; Osorio, J. C.; Fox, B. A.; Ravetch, J. V. |
| Article Title: | FcgRIIB is an immune checkpoint limiting the activity of Treg-targeting antibodies in the tumor microenvironment |
| Abstract: | Preclinical murine data indicate that fragment crystallizable (Fc)dependent depletion of intratumoral regulatory T cells (Treg) is a major mechanism of action of anti–CTLA-4. However, the two main antibodies administered to patients (ipilimumab and tremelimumab) do not recapitulate these effects. Here, we investigate the underlying mechanisms responsible for the limited Treg depletion observed with these therapies. Using an immunocompetent murine model humanized for CTLA-4 and Fcγ receptors (FcγR), we show that ipilimumab and tremelimumab exhibit limited Treg depletion in tumors. Immune profiling of the tumor microenvironment (TME) in both humanized mice and humans revealed high expression of the inhibitory Fc receptor, FcγRIIB, which limits antibody-dependent cellular cytotoxicity/phagocytosis. Blocking FcγRIIB in humanized mice rescued the Treg-depleting capacity and antitumor activity of ipilimumab. Furthermore, Fc engineering of antibodies targeting Treg-associated targets (CTLA-4 or CCR8) to minimize FcγRIIB binding significantly enhanced Treg depletion, resulting in increased antitumor activity across various tumor models. Our results define the inhibitory FcγRIIB as an immune checkpoint limiting antibody-mediated Treg depletion in the TME, and demonstrate Fc engineering as an effective strategy to overcome this limitation and improve the efficacy of Treg-targeting antibodies. ©2023 The Authors; Published by the American Association for Cancer Research. |
| Keywords: | controlled study; human tissue; protein expression; unclassified drug; nonhuman; antineoplastic agent; neoplasm; neoplasms; mouse; animal; animals; mice; animal tissue; cytotoxic t lymphocyte antigen 4 antibody; ipilimumab; ticilimumab; animal experiment; animal model; antineoplastic activity; regulatory t lymphocyte; immunoglobulin g; t-lymphocytes, regulatory; receptor blocking; cytotoxic t lymphocyte antigen 4; fc receptor iib; phagocytosis; antibody production; depletion; antibody dependent cellular cytotoxicity; antibody engineering; tumor microenvironment; chemokine receptor ccr8; ctla-4 antigen; humans; human; male; female; article; chemokine receptor ccr8 antibody; fc receptor iib antibody |
| Journal Title: | Cancer Immunology Research |
| Volume: | 12 |
| Issue: | 3 |
| ISSN: | 2326-6066 |
| Publisher: | American Association for Cancer Research |
| Date Published: | 2024-03-01 |
| Start Page: | 322 |
| End Page: | 333 |
| Language: | English |
| DOI: | 10.1158/2326-6066.Cir-23-0389 |
| PUBMED: | 38147316 |
| PROVIDER: | scopus |
| PMCID: | PMC10911703 |
| DOI/URL: | |
| Notes: | The MSK Cancer Center Support Grant (P30 CA008748) is acknowledged in the PDF -- Source: Scopus |
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