Table 1.
Summary table for the hallmark breast cancer studies using single-cell technologies.
| Technology | Sample/data | Main findings | Clinical significance | References | |
|---|---|---|---|---|---|
| The complexity of tumor-infiltrating lymphocytes (TILs) | scRNA-seq (10X Genomics) | 6,311 flow-sorted CD3+CD45+ T cells from two samples of TNBC | Discovery of minor subgroups of TILs that were related to immune-suppression | Biomarkers of the minor distinct TILs may serve as prognostic factors or therapeutic targets | (11) |
| scRNA-seq (10X Genomics) | Paired samples of pre- (998 cells) and post-neoadjuvant chemotherapy (1,499 cells) collected from 4 BRCA patients | ICOSL+ B cells boost anti-tumor immunity by enhancing the effector to regulatory T cell ratio | The critical role of the B cell subset switch in chemotherapy response, which has implications in designing novel anti-cancer therapies. | (12) | |
| Decomposition of tumor immune microenvironment using scRNA-seq | scRNA-seq (Fluidigm C1) | 515 cells from 11 patients representing the four subtypes of breast cancer | T lymphocytes and macrophages both display immunosuppressive characteristics | The characteristics of different BRCA subtypes that are shaped by tumor cells and immune cells in TME | (13) |
| scRNA-seq (inDrop); single-cell VDJ sequencing (10X Genomics) | 45,000 cells captured in the normal and malignant breast tissues, lymph nodes, and peripheral blood of 8 treatment-naive patients | Despite the significant similarity between normal and tumor tissue-resident immune cells, continuous phenotypic expansions specific to the TME was observed | Support a model of continuous activation in T cells and do not comport with the macrophage polarization model in cancer | (15) | |
| Spatial mapping of single-cell RNA-seq data | Spatial Transcriptomics (in-house) | Tumor tissue sections from BRCA patients diagnosed with HER2+ subtype | Demonstration of the heterogeneous nature of tumor-immune interactions and reveal interpatient differences in immune cell infiltration patterns | Potential for an improved stratification and description of the tumor-immune interplay, which is likely to be essential in treatment decisions | (16, 17) |
| Dissecting the tumor microenvironment using single-cell mass cytometry | Single-Cell Mass Cytometry | 26 million cells from 144 human breast tumors including and 50 non-tumor tissue samples | Relationship analyses between tumor and immune cells revealed characteristics of TME related to immunosuppression and poor prognosis | TME-based classification of BRCA will facilitate the identification of individuals for precision medicine approaches | (20) |
| Imaging mass cytometry | 855,668 cells in 381 images (289 tumors, 87 healthy breasts, and 5 liver controls) | Multicellular features of TME and novel subgroups of breast cancer that are associated with distinct clinical outcomes | Spatially resolved, single-cell analysis can characterize intratumor phenotypic heterogeneity with the potential to inform patient-specific diagnosis | (23) |