Table 2. Multimodal liquid biopsy studies including canonical CTCs and other cellular components.
| Reference | Clinical purpose | Clinical setting | Analytes | Analysis | Conclusions |
|---|---|---|---|---|---|
| Yu et al. (78) | Prognosis | MBC | Mesenchymal CTC | Count | Association of mesenchymal CTCs with disease progression |
| Bulfoni et al. (79) | Clinicopathological features | MBC | E-CTC, EM-CTC, MES, NEG | Detection by DEPArray-based strategy | Significant association between specific CD45 neg subpopulations and tumor subtypes, proliferation, and sites of metastatic spread. EM-CTC was significantly associated with poorer PFS and OS |
| Prognosis | |||||
| Giordano et al. (80) | Characterization | HER2+ MBC | EM-CTC | Gene transcripts of EMT-TF and CSC features | HER2 + MBCs had EMT-CTCs. An enrichment of CSCs was found in CD326− and CD45− cells. EM-CTC related to lower PFS and OS |
| Prognosis | |||||
| Gradilone et al. (81) | Prognosis | MBC | Mesenchymal CTC | Cytokeratin and markers of epithelial mesenchymal transition expression | The presence of mesenchymal markers on CTC more accurately predicted worse prognosis than the expression of cytokeratin alone |
| Papadaki et al. (82) | Prognosis | MBC | CSC+/partial-EMT+ CTCs | Cytokeratin expression | CSC+/partial-EMT+ CTCs correlated to lung metastases and decreased PFS. In HER2− patients related also to decreased OS and chemoresistance |
| Horimoto et al. (83); Ito et al. (84) | Prognosis | MBC | EM-CTC | Count and characterization | Higher CTCs number and mesenchymal CTC associated with negative prognostic impact on eribulin’s PFS. Total CTCs number related to worse OS |
| Mego et al. (87) | Prognosis | EBC | EM-CTC | Detection | EM-CTC have a negative prognostic value in primary BC |
| Markiewicz et al. (88) | Clinical significance | EBC | CTCs with different EMT status | Isolation and molecular characterization | MES characterized by the most aggressive phenotype, lymph nodes metastases, larger tumor size and higher risk of death. EM-CTC no impact on survival |
| Mu et al. (94) | Prognosis | MBC | CAMLs | Detection and count | CAMLs negative prognostic impact on PFS and OS. Combining with CTCs number, the presence of CAMLs with either <5 CTCs or >5 CTS had a negative prognostic impact on both PFS and OS, while only >5 CTCs and CAMLs—retained the statistical significance |
| Reduzzi et al. (100) | Prognosis | EBC and MBC | DPcells | Detection and count | Prognostic impact observed primarily in patients with <5 CTCs and triple-negative BC |
| De Giorgi et al. (115) | Correlation between CTC and inflammation based scores | MBC | Neutrophils, lymphocytes, platelets, monocytes | MLR, NLR, PLR, CTCs count | CTC and MLR are predictors of OS in MBC. CTC correlated with monocytes, in particular in triple-negative tumors |
| Carmona-Ule et al. (117) | Prognosis | MBC | RBCs | CTC culture | The presence of RBCs in the culture was linked to a worse patient outcome |
| Pereira-Veiga et al. (118) | Prognosis | EBC and MBC | RBCs | Proteomic composition | Different proteomic profile compared with healthy donors and between different tumor stages. Lysosome-associated membrane glycoprotein 2 emerge as a new RBCs marker with diagnostic and prognostic potential for MBC patients |
| Best et al. (120) | Diagnostic potential | BC | TEPs | RNA-profile | TEP-derived RNA profiles, were used to successfully identify BC patients with an average accuracy of 62%, distinguishing also molecular subtypes (HER2+, PIK3CA, and triple-negative) |
| Mego et al. (121) | Correlation between CTC and PB-T cell | IBC | PB T-cell | CTC enumeration, flow cytometry for T cell phenotype and function | IBC patients with CTCs in PB had abnormalities in adaptive immunity that could potentially impact tumor cell dissemination and initiation of the metastatic cascade |
| Szczerba et al. (122) | Identification and function | BC | CTC-associated WBCs | Isolation and characterization | CTC-neutrophil clusters were associated with a more unfavorable prognosis in patients with MBC, as opposed to singular CTCs or CTC clusters |
| Cole et al. (123) | Correlation with CTCs and prognosis | MBC | MDSCs | Enumeration | MDSCs correlated with CTCs and were associated with overall survival |
| Bergenfelz et al. (124) | Clinical significance | MBC | Monocytic-MDSCs | Flow cytometric analysis | High levels of monocytic-MDSCs tend to be related to a higher number of CTCs in patients with aggressive disease and de novo metastatic disease suggesting their role in the immunoregulatory switch responsible for cancer dissemination |
| Bidard et al. (125) | Prognosis | MBC | CECs | Count | CTC and CECs independent prognostic factor. Increase in CEC count was associated with improved time to progression, at the threshold of 20 CECs/4 mL |
| Codes et al. (126) | Therapy monitoring | HER2− MBC | CECs | Count | CTC and CECs independent prognostic factor. Baseline CECs >200 was associated with lower PFS |
| Mäurer et al. (127) | Disease relapse | EBC | CECs/CTC | Count | Patients with an increase in CETC/CTC numbers over the course of adjuvant RT had a significantly worse disease-free survival than patients with stable or decreasing CETC/CTC numbers |
Studies including circulating tumor cells and other cellular analytes are described in the table, categorized for clinical purpose and setting. CTCs, circulating tumor cells; MBC, metastatic breast cancer; E-CTC, cells expressing only epithelial markers; EM-CTC, epithelial-to-mesenchymal transition circulating tumor cell; MES, cells expressing only mesenchymal markers; NEG, cells negative for every tested marker; PFS, progression-free survival; OS, overall survival; HER2, human epidermal growth factor receptor 2; EMT-TF, epithelial-to-mesenchymal transition-inducing transcription factors; CSC, cancer steam cell; EBC, early-stage breast cancer; BC, breast cancer; EMT, epithelial-to-mesenchymal transition; CAMLs, cancer-associated macrophage-like cells; DPcells, dual-positive cells; MLR, monocyte-to-lymphocyte ratio; NLR, neutrophil-to-lymphocyte ratio; PLR, platelet-to-lymphocyte ratio; RBCs, red blood cells; TEPs, tumor-educated platelets; IBC, inflammatory breast cancer; PB, peripheral blood; WBCs, white blood cells; MDSCs, myeloid-derived suppressor cells; CECs, circulating endothelial cells; CETC, circulating epithelial tumor cell.