Table 1.
Figures-of-merit and results from clinical studies for representative technologies that isolate CTCs by biological and/or physical properties, and demonstrations of CTC analyses beyond enumeration.
| Technology (Principle) |
Target | Throughput | Recovery | Purity [WBCs/mL] |
Clinical Studies | Beyond Enumeration* | References** | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cell Line† | Medium | Efficiency | Cancer type‡ | Range (Median) CTCs/mL | Sensitivity | ||||||||
|
CellSearch™ (Biological) |
Ab-EpCAM | NA - Dedicated laboratories | SKBR3+++ T47D+++ BT20++ MDA-MB-231+ |
Blood (CellSave™) |
≥85% 75% 44% 12% |
CTC Test:
0.01–0.1% [103–104] Profile Kit: 21–95% [200–1000] |
CTC Test | Profile Kit |
CTC
Test Molecular (FACS or single cell picking + CNV sequencing) Profile Kit Molecular (RT-PCR, Sanger) Cytogenetics (FISH) |
26,78,79,87,216,222,226,264–266 | |||
| M-Breast (N=75) | 0–57 (4) | 4–2432 (116) | NR | ||||||||||
| NSCLC (N=71) | 0–53 (4) | 5–1801 (145) | |||||||||||
| Others (N=90/52) | 0–10 (NR)/0–17 (NR) | 12%/63% | |||||||||||
| CTC Test | |||||||||||||
| M-Breast (N=422) | 0–3150 (11 mean) | 26% | |||||||||||
| M-Colorectal (N=196) | 0–14 (0.1 mean) | 17% | |||||||||||
| M-Lung (N=99) | 0–290 (4 mean) | 14% | |||||||||||
| M-Ovarian (N=29) | 0–14 (0.8 mean) | 23% | |||||||||||
| M-Pancreatic (N=16) | 0–4 (0.3 mean) | 5% | |||||||||||
| M-Prostate (N=123) | 0–435 (10 mean) | 41% | |||||||||||
| Non-cancer (N=199) | 0–0.4 (0 mean) | – | |||||||||||
| Healthy (N=145) | 0–0.1 (0 mean) | ||||||||||||
|
| |||||||||||||
|
CTC Chip
(Biological) |
Ab-EpCAM | 1 mL/h | H1650++++ SKBR3+++ PC3++ T24+ |
PBS | 76±8% 74±5% 80±6% 76±7% |
34±8% [233–9000] |
Breast (N=10) | 5–176 (78) | 100% |
Clinical Molecular (RT-PCR, EGFR mutations) |
36,267 | ||
| Colon (N=10) | 0–375 (57) | 90% | |||||||||||
| NSCLC (N=55) | 5–1281 (73) | 100% | |||||||||||
| Pancreatic (N=15) | 9–831 (120) | 100% | |||||||||||
| L-Prostate (N=7) | 25–174 (103) | 100% | |||||||||||
| M-Prostate (N=19) | 16–292 (50) | 100% | |||||||||||
| Healthy (N=20) | 0–0 (0) | – | |||||||||||
|
| |||||||||||||
|
GEDI Micropillar
Chip
(Biological and Physical - Size) |
Ab–PSMA | 1 mL/h | LNCaP++++ | PBS Blood |
97±3% 85±5% |
62±2% [10] |
Prostate (N=4) | NR (27 ±4 mean) | ND** |
Cell
line Molecular (RT-PCR, NGS CNV sequencing from single nuclei) Drug susceptibility (on-chip culture) |
39,49,73,137,138,268 | ||
| Prostate (N=30) | 0–1200 (54) | NR | |||||||||||
| Healthy (N=10) | 0–22 (3) | – | |||||||||||
| Ab-EpCAM/ hMUC1 |
Capan-1+++ PANC-1++ |
PBS | 70±3% 61±3% |
NR | PDAC (N=1) | 102–135 (NA) | – | ||||||
| Ab-EpCAM | ND | NR | PDAC (N=11)*** | 0–59 (9) | 73% | ||||||||
| Cystic lesion (N=21)*** | 0–22 (0) (4 mean) | 33% | |||||||||||
| Healthy (N=19)*** | 0–3 (0) | – | |||||||||||
| Ab-HER2 | SK-BR-3+++ | Blood | 78±22% | NR | M-Breast (N=5) | 31–115 (74 mean) | ND° | ||||||
| MCF-7++ | 25±6% | M-Gastric (N=4) | 33–224 (120 mean) | ||||||||||
| MDA-MB-468− | 6±13% | Healthy (N=3) | NR-NR (5 mean) | – | |||||||||
|
| |||||||||||||
|
Sinusoidal
Chip (Biological) |
Ab-EpCAM/ Ab-FAPα |
1.5 mL/h |
EpCAM SKBR3+++ SKBR3+++ FAPα Hs578T++ Hs578T++ |
Blood PBS Blood PBS |
77±2% 85±4% 75±8% 76±8% |
~90% [3±3] |
EpCAM | FAPα |
Clinical CTC release (enzymatic) Molecular (RT-PCR, PCR-LDR, Sanger) Cytogenetic (FISH) Cell line Expansion (culture) Antigen expression (Flow cytometry) |
24,29,31,34,74,159 | |||
| M-Breast (N=10) | 1–278 (48) | 0.5–179 (24) | 80% | ||||||||||
| M-Colorectal (N=5) | 7–111 (17) | 10–280 (24) | 100% | ||||||||||
| M-Ovarian (N=9) | 42–680 (100) | 4–137 (32) | 100% | ||||||||||
| CR prostate (N=5) | 2–39 (9) | 13–27 (18) | 100% | ||||||||||
| M-PDAC (N=11) | 4–105 (20) | 6–83 (17) | 100% | ||||||||||
| Non-cancer (N=6) | 0.5–4 (3) | 0–4 (2) | – | ||||||||||
| Healthy (N=11) | 0–1 (0) | – | – | ||||||||||
| Ab-EpCAM | L-PDAC (N=4) | 9–19 (11) | – | 100% | |||||||||
|
Clinical
Recoveries EpCAM: M-PDAC (N=3) FAPα: M-PDAC (N=3) |
87±2% 79±7% |
M-PDAC (N=4) | 9–95 (51) | – | 100% | ||||||||
| Healthy (N=4) | 0–2 (0) | – | – | ||||||||||
| PDX-PDAC† | |||||||||||||
| Pre BKM120 (N=8) | 28–254 (106) | – | 100% | ||||||||||
| Post BKM120 (N=8) | 0–317 (9) | – | 63% | ||||||||||
| Pre vehicle (N=4) | 17–172 (94) | – | 100% | ||||||||||
| Post vehicle (N=8) | 22–582 (48) | – | 100% | ||||||||||
| No tumour (N-5) | 0–4 (0) | – | – | ||||||||||
| Ab-CD33/CD34/CD117 | KG-1++++ | PBS | 64±4% | 88–99% specificity | AML (N=39) | 0–2684 (90) | 79%– | ||||||
| Healthy (N=3) | 0–4 (1) | ||||||||||||
|
| |||||||||||||
|
Herringbone
Chip (Biological) |
Ab-EpCAM | 1–1.5 mL/h | SKBR3+++ PC3++ MDA-MB-231+ |
Blood | 97±1% 92±5% 3±1% |
14±0.1% [~5600] |
M-Prostate (N=15) | 0.6–3168 (63) | 93% |
Clinical CTC release (enzymatic, mechanical, thermal) Molecular (RT-PCR, Sanger, NGS RNAseq) Cell line Cytogenetic (FISH) Expansion (culture) |
28,41,65,75,141,142,174,269 | ||
| Healthy (N=10) | 0–8 (1) | – | |||||||||||
| L-Prostate (N=19) | 38–222 (95), PSA+ | 56% | |||||||||||
| M-Prostate (N=36) | 14–653 (32), PSA+ | 64% | |||||||||||
| M-Prostate (N=25) | 0–165 (7), PSA+/PSMA+ | 72% | |||||||||||
| NB508 | Blood | 35±3% | 1.7±2.1% | Pancreatic mouse model | 20–5469 (310) | – | |||||||
| Ab-EpCAM/ HER2/EGFR |
PC3 MDA-MB-231 |
Blood | 94±2% 94±2% |
NR | Breast (N=17) Breast (N=8) Lung (N=8) Healthy (N=6) |
0-NR (NR) 0–45 (4) 0–5 (4) 0–0.9 (0.1) |
41% 88% 88%- |
||||||
| 12 Ab mixture | SK-MEL-28 | Blood | 90% | 0–0.77% | Melanoma (N=41)‡ | 0–53 (3) | 79% | ||||||
| Healthy (N=10) | 0–0.8 (0.4) | – | |||||||||||
|
| |||||||||||||
|
Si
Nanopillar Chip (Biological) |
Ab-EpCAM | 1 mL/h | MCF-7++++ PC3++ T24+ |
Blood | >95% | ND | L-Prostate (N=2) | 0–3 | ND† |
Clinical CTC release (thermal) Molecular (Single cell WGA and Sanger, NGS WES, NGS WGS) Cell line Expansion (culture) |
52,128,147,148,150,167 | ||
| M-CS Prostate (N=20) | 0–3 (1) | ND† | |||||||||||
| M-CR Prostate (N=14) | 0–33 (3.5) | ND† | |||||||||||
| L-Prostate (N=31) | 0–10 (0.9 mean) | ND‡ | |||||||||||
| M-Prostate (N=117) | 0–21 (2.4 mean) | ND‡ | |||||||||||
| Healthy | ND | – | |||||||||||
| Lysis and biotin-Ab labelling then 1 mL/h | CFPAC-1++++ AsPC-1+++ BxPC-3++ PANC-1++ |
Blood | 93±4% 88±2% 86±3% 65±5% |
ND | PDAC – Stage 1 (N=3) | 0–0 (0) | 0% | ||||||
| PDAC – Stage 2 (N=28) | 0–1.5 (0.25) | 61% | |||||||||||
| PDAC – Stage 3 (N=14) | 0–2.25 (0.25) | 79% | |||||||||||
| PDAC – Stage 4 (N=27) | 0–12 (1.25) | 96% | |||||||||||
| Non-PDAC (N=28) | 0–0.25 (0) | 4%* | |||||||||||
|
| |||||||||||||
|
Ephesia
Chip (Biological) |
Ab-EpCAM | RosetteSep WBC removal then 3 mL/h | MCF-7++++ SKBR3+++ PC3++ A549+ |
PBS | >90% >90% 79±7% 19±7% |
NR [<100] | M-Breast (N=5)** | 0–35 (7) | 75% | CTC release
(magnetic) Cell line Molecular (qPCR) Expansion (culture) |
60 | ||
| M-Prostate (N=8)** | 0–5 (2) | 80% | |||||||||||
| Healthy (N=10) | 0–0 (0) | – | |||||||||||
|
| |||||||||||||
|
Velocity
valley (Biological) |
Ab-EpCAM | Labelling then 0.6–2 mL/h*** | VCaP++++ SKBR3+++ |
PBS | 97±4% 95±3% |
4–19%
[75–400]° |
Prostate (N=21) | 14–116 (43) | 100% | CTC release (magnetic,
aptamer anti-sense) Cell line Integrated chemotaxis assay |
114,115 | ||
| Healthy (N=3) | 0–0 (0) | – | |||||||||||
| VX2 cell line xenograft (N=6) | 3–26 (17) | – | |||||||||||
|
Magnetic
ranking (Biological) |
Labelling then 0.6 mL/h | SKBR3+++ PC3++ MDA-MB-231+ |
Blood (CellSave™) | 97±3% 90±2% 90±3% |
4–5% [2000] |
L-Prostate (N=14)°° | 2–10 (4) | 100% | 118,119 | ||||
| M-CR-Prostate (N=10)°° | 1–5 (2) | 100% | |||||||||||
| Healthy (N=9)°° | 0–0.6 (0.2) | – | |||||||||||
|
| |||||||||||||
|
Micro-Hall (Biological) |
Ab-EpCAM/ HER2/EGFR/ MUC1 |
~3 h assay time | MDA-MB-231+ | Lysed and concentrated blood | 90% | NA Detection only |
Breast, stage IIIC (N=9) | 0.4–25 (7) | 91% | – | 121 | ||
| Breast, stage IV (N=11) | 1.5–31 (8) | ||||||||||||
| Healthy (N=15) | 0–1 (NR) | – | |||||||||||
|
| |||||||||||||
| Halloysite Nanotubes (Biological) | Ab-EpCAM/ PSMA + E-selectin |
Ficoll then 4.8 mL/h |
ND (~50% efficiency selecting KG1a++++ cells via CD34 selection) |
50–80% [3–60]°°° |
Breast (N=3) | 17–60 (60) | 100% |
Clinical Short term culture, drug susceptibility |
153,154 | ||||
| Lung (N=2) | 11–31 | 100% | |||||||||||
| Other cancers (N=2) | 13–30 | 100% | |||||||||||
| Healthy (N=8) | 0–4 (0) | – | |||||||||||
| BT20++++ | Buffy coat | 82±19% | NR | M-Breast (N=3)°°°° | 1495–2534 (2534) | 100% | |||||||
| M-Prostate (N=2)°°°° | 3155–53370 | 100% | |||||||||||
| M-Colorectal (N=1)°°°° | 1039 | 100% | |||||||||||
| M-Renal (N=1)°°°° | 4951 | 100% | |||||||||||
| Healthy (N=4) | 6.6±9 | – | |||||||||||
|
| |||||||||||||
|
iChip (Biological + Physical) |
Ab-EpCAM +
size (posiChip) |
Labelling then 8 mL/h |
SKBR3+++ PC3-9++ MDA-MB-231+ MCF10A-LBX1+/− |
Blood | 99±4% 90±5% 78±8% 11 ±3% |
0.02–43% [1500] | M-Breast (N=12) | 0–3.7 (0.4) | 42% |
Clinical
–posIchip Molecular (RT-PCR, Sanger) Clinical –negIchip Molecular (RT-PCR, Single cell RNA-seq, RNA-ISH, FISH) Expansion (3D culture, drug susceptibility, xenograft) Proteomics (Multiplexed mass spectrometry) |
21,107,111,145,232,270 | ||
| M-Colorectal (N=2) | 0.3–1.1 | 50% | |||||||||||
| M-Lung (N=2) | 0–1.2 | 50% | |||||||||||
| M-Pancreatic (N=6) | 0–1.4 (0.5) | 50% | |||||||||||
| M-Prostate (N=20) | 0–611 (1.4) | 75% | |||||||||||
| CR-Prostate (N=41) | 0.5–610 (3.2) | 90% | |||||||||||
| Healthy (N=13) | 0–0.3 (0.2) | – | |||||||||||
| Ab-CD45/ CD15/CD66b + size (negiChip) |
MCF10A MCF10A-LBX1 NB408 |
Blood | 97±2% 97±2% 95±3% |
<0.1% [32000] |
Glioblastoma, progressive (N=23) | 0–33 (12) | 58% | ||||||
| Glioblastoma, stable (N=43) | 0–30 (2) | 29% | |||||||||||
| Healthy (N=6) | 0–6.4 (1.9) | – | |||||||||||
| Pancreatic mouse model (N=11) | 0–1694 (118) | NR | |||||||||||
| M-Breast (N=19)† | 0.2–43.5 (1.6) | 81% | |||||||||||
|
| |||||||||||||
|
ApoStream™ (Physical) |
DEP | ~1 h assay time | SKOV3 MDA-MB-231 4–23 cells spiked |
Blood + Ficoll | 75
±3% 71 ±2% 68 ±10% |
~0.1–1%‡ [~10000] |
L-Breast (N=47)* | 0–5.7 (0.6 mean) | 54% |
Clinical Molecular (ice-COLD-PCR) Cytogenetic (FISH) |
66,209–214 | ||
| M-Breast (N=167)* | 1–2000 (29) | 93% | |||||||||||
| M-Pancreatic (N=18)* | 0–9 (2)** | 61% | |||||||||||
| Renal cell carcinoma (N=23)* | 0–5 (0.8) | 30% | |||||||||||
| M-NSCLC adenocarcinoma (N=14) | 0.4–64.9 (9.2) | 79%*** | |||||||||||
| M-NSCLC squamous (N=6) | 0–0.5 (0) | 0%*** | |||||||||||
| M-Ovarian (N=6) | 0–0.7 (0.3) | 0%*** | |||||||||||
| M-Breast (N=20) | 0–4.8 (0.8) | 15%*** | |||||||||||
| Healthy (N=20) | 0–1.9 (0.3) | –** | |||||||||||
|
| |||||||||||||
|
Dean
Flow Fractionation (Physical) |
Size Deformability |
3 mL/h | HeLa,
MDA-MB-231, MCF-7 |
0.5X blood | 85% | 7±9%° [440±320] |
M-Lung (N=20) | 5–88 (31) | 100% |
Cell
line Expansion (culture) Clinical Molecular (ice-COLD-PCR, Sanger) Cytogenetic (FISH) |
206,207 | ||
| Healthy (N=20) | 0.3–1.3 (0.7) | – | |||||||||||
| Lysis then 12 mL/h |
MCF-7, MDA-MB-231, T24 | Lysed and 2X concentrated blood | 71–88% | 0.1–86%°° [9–29824] |
Lung (N=15) | 12–459 (97) | 100% | ||||||
| Breast (N=15) | 12–322 (44) | 100% | |||||||||||
| Healthy (N=10) | 0–7 (NR) | – | |||||||||||
|
| |||||||||||||
|
Vortex
Chip (Physical) |
Size Deformability |
24 mL/h (Vortex) | MCF-7 M395 PC-3 |
0.1X blood | 8–26% ~20% 9±1% |
57–95% [1–13] |
Breast (N=4) | 3–7 (5) | 50% |
Cell
line Molecular (RT-PCR) Expansion (culture) |
56,204,271 | ||
| Lung (N=8) | 3–42 (26) | 88% | |||||||||||
| Healthy (N=4) | 2–5 (3) | – | |||||||||||
| 24 mL/h† (Vortex HT) |
MCF-7 | 0.1X blood | 28–37%‡ | 20±14% [1–93] |
M-Breast (N=22)* | 0.8–23.8 (4.1) | 86% | ||||||
| M-Lung (N=15)* | 0.5–24.2 (3.5) | 73%** | |||||||||||
| Healthy (N=10) | 0.0–1.3 (0.5) | – | |||||||||||
|
| |||||||||||||
|
2D Parylene
Microfilters (Physical) |
Size Deformability |
Fixation then 225 mL/h |
J82/ T24/ MCF-7/ SK-BR-3/ MDA-MB-231 |
0.5X blood + 1% formalin | NR; ≥1/5 cells recovered in 28/29 tests | NR | M-Bladder (N=6) | 0–6 (0) | 50% |
Clinical Molecular (qPCR telomerase activity) Expansion (fibroblast culture) |
57,80,196,200 | ||
| M-Breast (N=11) | 0.1–8 (3) | 100% | |||||||||||
| M-Colorectal (N=12) | 0–3 (1) | 83% | |||||||||||
| M-Prostate (N=28) | 0–24 (9) | 96% | |||||||||||
| Healthy (N=10) | 0–0 (0) | – | |||||||||||
| Fixation then 200 mL/h | CAF-23 | 0.5X blood + 1% formalin | 95±3% | NR | CK(+) | FAPα(+) | |||||||
| L-Breast (N=13) | 0–1.9 (0.4) | 0–0.3 (0) | 85% | ||||||||||
| M-Breast (N=34) | 0–13.1 (1.7) | 0–15.6 (0.5) | 100% | ||||||||||
| M-Colorectal (N=6) | 0–37.9 (0.3) | 0.1–3.7 (0.5) | 100% | ||||||||||
| L-Prostate (N=3) | 0–0.1 (0) | 0–0.4 (0.1) | 67% | ||||||||||
| NR | PC3 | Blood + Ficoll | 71±11% | ~0.1%*** [103] |
M-CR Prostate (N=215) | NA – High telomerase activity was detected in 48% of patients | |||||||
| DU145 | 68±8% | ||||||||||||
|
| |||||||||||||
|
3D PEGDA
Microfilters (Physical) |
Size Deformability |
6 mL/h | MCF-7 HT29 U87 |
PBS | 98±1% 90±3% 62±5% |
~0.01–0.1%° [800–8000] |
Healthy (N=7) | 0–0 (0) | 0–0 (0) | – | 197 | ||
| M-Lung (N=8) | 0–3 (1) | 75% | |||||||||||
| M-Other cancers (N=6) | 0–1 (0.5) | 67% | |||||||||||
| Healthy (N=6) | 0–0 (0) | – | |||||||||||
|
| |||||||||||||
| Cluster chip (Physical) | Size (CTC clusters) |
2.5 mL/h |
MDA-MB-231 ≥4 cells in cluster 3 cells 2 cells 1 cell |
Blood | >90% 70% 41% 0% |
NR (only relative purity reported) | Breast (N=27) Melanoma (N=20) Prostate (N=13) |
Clusters/mL NR (0.5 mean) NR (0.2 mean) NR (0.3 mean) |
41% 30% 31% |
Clinical Molecular (RT-PCR-NGS) |
50 | ||
Cell line antigen expression: −no detectable expression,
1000–15000 (low),
15000–50000 (moderate),
50000–150000 (high),
>150000 (very high) molecules per cell.
Abbreviations: AML (acute myeloid leukemia), CR (castration resistant), CS (castration sensitive), L (localized), M (metastatic), NSCLC (non-small cell lung cancer), PDAC (pancreatic ductal adenocarcinoma), PDX (patient derived xenograft), SCCHN (squamous cell carcinoma of the head and neck).
Only abbreviation not in main text: FACS (fluorescence activated cell sorting).
Some data is not reported (NR), not determined (ND), or not applicable (NA) to the technology.
CTCs were detected in 90% of clinical samples, but thresholds for positivity were not established from controls.
Peripheral blood samples were collected in CellSave™ tubes.
CTCs were detected in 100% of clinical samples, but thresholds for positivity were not reported from controls.
PDAC-PDX mouse models were treated with BKM120, a phosphatidylinositol-3-kinase inhibitor, versus vehicle control.
Patients were in treatment. A median (range) CTC count/mL was 10 (4–53) for pre-treatment patients (N=21) with 100% clinical sensitivity.
CTCs were detected in 1/2 (50%), 6/10 (60%), and (93%) for L-, M-CS, and M-CR prostate cancer samples, respectively.†,
Thresholds for positivity were not established from controls.
Clinical sensitivity was established at a threshold of 1 CTC per 4 mL; 1/28 non-adenocarcinoma controls detected positive for CTCs (96.4% specificity).
Reported CTC counts were normalized to a 7.5 mL blood draw, but the volume processed for each sample was not explicitly reported by the authors.
In two reports,117,119 RBCs were lysed, and WBCs were removed by magnetic negative affinity-selection against CD15 before anti-EpCAM labelling.
From prostate patients (N=5), 74±22 WBCs/mL were observed at 19% purity by Mohamadi, et al.114 For the VX2 cell line rabbit xenograft,115 ~400 WBCs/mL were observed (0.4% WBC recovery assuming 106 WBCs/mL). Purity for Muhanna, et al115 was calculated to be 4% using 400 WBCs/mL and the median of 17 total CTCs/mL observed in xenograft samples.
Peripheral blood samples were collected in CellSave™ tubes.
Purity was assessed by counting EpCAM(−)/DAPI(+) cells 5 days after isolation.
Patients had advanced, stage IV disease.
To retain viability, CTCs were identified by immunostaining against EpCAM and HER2 only.
The authors reported a 99.33 ±0.56% reduction in WBC counts and assumed 1600000 WBCs/mL (10720 ±8960 WBCs/mL). Dividing the highest median CTC count reported by this number yielded a purity of 0.3 ±0.3%.
CTC counts reported in this table were normalized to a 7.5 mL blood draw, but the volume processed for each sample was not explicitly reported by the authors.
The authors only stained for CK and CD45, noted a large number of cells that did not stain for either marker, and suggested the presence of abundant mesenchymal CTCs.
Without taking into false positives from healthy donors, 100%, 33%, 83%, and 95% of patients with M-NSCLC-adenocarcinoma, M-NSCLC-squamous, M-ovarian, and M-breast cancers, respectively, had at least 1 CTC detected per sample. However, if thresholds for positivity are established by either the maximum number of CTCs detected in a healthy patient (1.9 CTCs/mL) or mean + 3 standard deviations (1.8 CTCs/mL), 79%, 0%, 0%, and 15% of these patients tested positive for CTCs by the assay.
A ratio of CTCs/WBCs of ~10% and background cell counts of 441 ±320 WBCs/mL were reported.206 By dividing the highest reported median CTC count by the average WBC count yielded a purity of 6.6 ±8.8%.
Both CTC counts and WBC counts (5246 ±6575 WBCs/mL) were reported for each sample, and the range reported is derived directly from this data. Average purity was 9 ±19%.207
In a third generation device, Vortex High Throughput (Vortex HT), the chip’s architecture was altered for improved trapping dynamics, and volumetric throughput was doubled to 48 mL/h. However, each sample was processed through the chip twice to improve recovery, reducing effective throughput to the original 24 mL/h.
Recovery values reflect two rounds of processing, as was performed for clinical samples.
41% of the cells classified as CTCs were DAPI(+)/CK(−)/CD45(−) and were discriminated from WBCs solely by nuclear size (>9 μm) and nuclear-to-cytoplasmic ratio (>0.8). Lack of CK positivity (epithelial marker) was subsequently interrogated by staining for EpcAM (epithelial marker) and vimentin and N-cadherin (mesenchymal markers). 6% of all CTCs stained positive for the mesenchymal markers. Within the reported clinical data, 42% of all purported CTCs did not express any epithelial or mesenchymal markers but were classified as CTCs based on nuclear staining alone.
An 80% clinical sensitivity was reported, but lung cancer patients #14, #23, #37, and #38 had <1.25 CTCs/mL, yielding a 73% sensitivity (11/15 patients detected positive).
A 1500-fold enrichment was achieved, corresponding to a WBC level on the order of 103 WBCs/mL.
A clearance efficiency (percentage of unclogged pores per mL blood) of 96% was reported with 104–105 pores. Thus, we assumed impurities in the range of 800–8,000 WBCs/mL and calculated purity based on the highest median count of CTCs acquired from clinical samples.