Table 1.
Summary of studies attempting to isolate CTCs from patients with high-grade gliomas.
| Author | Cell enrichment | Cell characterization | Results | Limitations |
|---|---|---|---|---|
| PUBLICATIONS POSITIVELY IDENTIFYING CTCs IN BRAIN TUMOR PATIENTS | ||||
| Müller et al. (3) | MNCs isolated by Ficoll density gradient centrifugation | GBM patients | n = 29/141 | Low detection rate |
| Cytospins prepared from MNCs GFAP positive single cells isolated by micromanipulation | Chromogenic and fluorescent IHC (GFAP, CD45, EGFR) | Observed association between EGFR amplification and release of CTCs Common genomic aberrations in CTCs and GBM tumors | ||
| Further characterization of CTCs and associated tumor | ||||
| Comparative genomic hybridization | ||||
| Sequence analysis | ||||
| FISH | ||||
| Sullivan et al. (87) | Blood processed through a CTC-iChip® (magnetically tagged CD45 and CD16) | GBM patients | n = 26/87 | Limited dataset |
| IF-guided single-cell micromanipulation used to isolate single CTCs (EGFR, MET and CDH11) | IHC glioma marker panel [SOX2, Tubulin, beta-3, EGFR, A2B5 and c-MET (STEAM)] | RNA-ISH demonstrated an enrichment for mesenchymal transcripts and a reduction of neural differentiation markers | Could not determine whether surgical or radiation induced disruption of the blood–brain barrier enhances CTC dissemination | |
| FISH used to determine EGFR gene amplification in CTCs from known amplified cases | ||||
| Further CTC characterization by qRT-PCR and dual color RNA-ISH assay | ||||
| MacArthur et al. (88) | Blood samples centrifuged in OncoQuick tubes | High-grade glioma patients | n = 8/11 pre-radiotherapy | Limited pilot data |
| Incubated with a telomerase-responsive adenoviral probe (via GFP expression) Secondary Immunofluorescence (Nestin and EGFR) | n = 1/8 post-radiotherapy | Need more serial measurements throughout the treatment and disease course for each patient | ||
| EGFR amplification in CTCs correlates with solid tumors | Telomerase is elevated in other tumor histologies | |||
| PUBLICATIONS NEGATIVELY IDENTIFYING CTCs IN BRAIN TUMOR PATIENTS | ||||
| Böhm et al. (89) | Total cellular RNA extracted from whole blood using the QIAmp RNA blood mini kit (Qiagen) | High-grade astrocytoma and GBM patients | n = 0/20 | Sample size |
| RT-qPCR assay for the detection of mRNA encoding GFAP and B2M (positive control) | Insufficient technology | |||
| Martens et al. (90) | Cytocentrifugation | Astrocytoma patient | n = 0/1 | Only one patient and sample tested |
| Chromogenic and fluorescent IHC (GFAP) | Insufficient technology | |||