TMIC-46. SINGLE-CELL MAPPING OF HUMAN BREAST CANCER BRAIN METASTASES REVEALS PROGNOSTICALLY RELEVANT IMMUNE LANDSCAPES
Abstract Brain metastases are associated with a particularly poor prognosis in breast cancer and improved treatment strategies are much needed. The patient-individual role of immunotherapy and anti-tumor immune control in breast cancer brain metastases (BCBM) is still poorly understood. Here, we cha...
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| Published in: | Neuro-oncology (Charlottesville, Va.) Vol. 25; no. Supplement_5; p. v288 |
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| Main Authors: | , , , , , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
US
Oxford University Press
10-11-2023
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Abstract
Brain metastases are associated with a particularly poor prognosis in breast cancer and improved treatment strategies are much needed. The patient-individual role of immunotherapy and anti-tumor immune control in breast cancer brain metastases (BCBM) is still poorly understood. Here, we characterized the niche-specific tumor microenvironment of BCBM at single-cell resolution in a clinically annotated patient cohort that underwent surgery at Heidelberg University Hospital (n = 156). Quantification of T cell infiltrates across whole tissue sections of n = 137 BCBM revealed strong inter-patient heterogeneity of T cell abundance. Of note, high CD8 T cell densities predicted prolonged overall survival independent of established prognostic factors. Deeper phenotyping of BCBM T cells and matched blood samples by flow cytometry showed a specific enrichment of a CD103+ tissue resident-like CD8 T cell subset expressing high levels of activation markers and checkpoint molecules in BCBM. In contrast to a general T cell enrichment in the stroma, this subset was detected more frequently within tumor islands, which might suggest its anti-tumor reactivity. We investigated potential regulators of T cell infiltration and function in the brain metastatic niche focusing on the triple negative breast cancer sub-cohort (n = 49) concluding the following: i) The quantification of a broad range of immune cells, incl. myeloid cells, NK, and B cells, in whole tissue sections revealed distinct immune ecotypes associated with T cell infiltrates. ii) An in-depth characterization of all major immune and stromal cells by single nuclei RNA-sequencing (n = 28/49) allowed for identification of potential cellular and molecular interaction partners, which was confirmed by iii) analysis of their neighborhoods by spatial transcriptomics in a targeted, single-cell resolving approach (n = 8/28). We anticipate that our findings will reveal immunoregulatory cell subsets and molecules and potentially contribute to improving immunotherapeutic approaches for BCBM patients in the future. |
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| ISSN: | 1522-8517 1523-5866 |
| DOI: | 10.1093/neuonc/noad179.1112 |