MINDEC-An Enhanced Negative Depletion Strategy for Circulating Tumour Cell Enrichment

Our plain-English summary of MINDEC-An Enhanced Negative Depletion Strategy for Circulating Tumour Cell Enrichment, by M. Lapin, K. Tjensvoll, S. Oltedal, et al (Scientific Reports, 2016).

The study

• Authors: M. Lapin, K. Tjensvoll, S. Oltedal, T. Buhl, B. Gilje, R. Smaaland, O. Nordgård
• Journal: Scientific Reports
• Published: 2016;6:28929
• Cited by: 34 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Most current methods of circulating tumour cell (CTC) enrichment target the epithelial protein EpCAM, which is commonly expressed in adenocarcinoma cells. However, such methods will not recover the fraction of CTCs that have a non-epithelial phenotype due to epithelial-mesenchymal transition. For phenotype-independent CTC enrichment, we developed a new enhanced negative depletion strategy-termed MINDEC-that is based on multi-marker (CD45, CD16, CD19, CD163, and CD235a/GYPA) depletion of blood cells rather than targeted enrichment of CTCs. Here we validated the performance of MINDEC using epithelial and mesenchymal cancer cell lines, demonstrating a mean recovery of 82 ± 10%, high depletion (437 ± 350 residual white blood cells (WBCs)/mL peripheral blood), linearity between spiked and recovered cells (correlation coefficient: r = 0.995), and a low detection limit (≥1 cell recovered in all four replicates spiked with 3 cells). For clinical validation of this method, we enumerated CTCs in peripheral blood samples from patients with metastatic pancreatic cancer, detecting CTCs in 15 of 21 blood samples (71%) from 9 patients. The promising performance of the MINDEC enrichment strategy in our study encourages validation in larger clinical trials.

In plain English

This laboratory study, from Stavanger University Hospital in Norway, described and tested MINDEC, a new way to separate rare tumour cells from blood. Instead of capturing tumour cells directly, it removed blood cells using magnetic beads attached to antibodies against five blood-cell markers. The study did not examine asbestos or any exposure. Its only link to asbestos-related disease was that one of the eight cancer cell lines tested was a mesothelioma cell line, SDM103T2. When 1000 cells of each line were added to processed blood, a mean of 82% (plus or minus 10%) were recovered across the eight lines. Recovery was lowest for the mesothelioma line, at about 50%. On average 437 white blood cells per mL of blood remained. Recovery was 25% lower when tumour cells were added before an initial density-separation step. In 21 blood samples from 9 patients with metastatic pancreatic cancer, cells classified as circulating tumour cells, based on staining and appearance, were detected in 15 samples (71%). The authors concluded the method warrants validation in larger clinical studies. They noted its pre-enrichment step as a drawback.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: laboratory method-development and validation study (cancer cell lines added to blood samples), with a small proof-of-principle test in patient blood samples
• Who was studied: Eight human cancer cell lines (three pancreatic, four breast, and the mesenchymal human mesothelioma cell line SDM103T2) added to blood from healthy volunteers; 21 blood samples from 9 patients with metastatic pancreatic cancer receiving chemotherapy at Stavanger University Hospital, Norway, between July 2015 and February 2016; and blood samples from 13 volunteers
• Main results:
  • Across all eight cell lines, mean recovery of added tumour cells was 82 plus or minus 10% (range 50 to 100%)
  • Recovery ranged from 50 plus or minus 9% for the mesothelioma cell line SDM103T2 to 100 plus or minus 10% for the breast cancer cell line ZR-75-1
  • Mean residual white blood cell count after processing was 437 plus or minus 350 per mL of peripheral blood (range 98 to 1533)
  • In dilution experiments with ZR-75-1 cells, recovered numbers rose in line with added numbers (slope 0.83, Pearson's r 0.995)
  • At least 1 cell was recovered in each of the four samples to which 3 cells had been added
  • Recovery was 25% lower when tumour cells were added to whole blood before density gradient centrifugation than when added after it
  • The patient-sample test was described as detecting potential circulating tumour cells; cells were counted as such based on staining and appearance (visible nucleus, no beads attached, EpCAM-MCAM expression, no CD45 expression, round or oval shape)
  • In patients with metastatic pancreatic cancer, cells classified as circulating tumour cells were detected in 15 of 21 blood samples (71%), with a mean of 2 plus or minus 2 per 9 mL of blood
  • Seven of the nine patients had cells classified as circulating tumour cells in at least one blood sample
  • Apparent tumour cell clusters were seen in 3 of the 21 patient samples (14%)
• The authors' conclusion: The authors concluded that their initial results suggest the MINDEC method warrants validation in larger clinical studies
• Limitations the authors state:
  • The method requires a pre-enrichment step to remove red blood cells and platelets, during which tumour cells were lost
  • Pan-cytokeratin markers were not used for detection in patient samples; the authors think using them would have raised the detection rate
  • Because recovery differed widely between cell lines, the recovery figures are not necessarily comparable with other methods validated with different cell lines
  • Some healthy control samples contained marker-positive cells of uncertain identity
  • Recovery of the mesothelioma cell line was low compared with epithelial cell lines, possibly because it expresses blood-cell markers

Topics

Medical terms in this study, explained in our Lexicon: Adenocarcinoma, Clinical Trial.

Related studies

• EpCAM-independent capture of circulating tumor cells with a 'universal CTC-chip' — Y. Chikaishi, K. Yoneda, et al. (2017)
• Circulating tumor cells (CTCs) in malignant pleural mesothelioma (MPM) — K. Yoneda, F. Tanaka, et al. (2014)
• Detection of circulating tumour cells in peripheral blood of patients with malignant pleural mesothelioma — J. Raphael, C. Massard, et al. (2015)
• Expression of the small cell carcinoma antigens of cluster-5 and cluster-5A in primary lung tumours — A. Maier, U. Schmidt, et al. (1989)
• Detection of circulating tumor cells with a novel microfluidic system in malignant pleural mesothelioma — K. Yoneda, T. Kuwata, et al. (2019)
• A liquid biopsy for detecting circulating mesothelial precursor cells: A new biomarker for diagnosis and prognosis in mesothelioma — B.T.V. Duong, L. Wu, et al. (2020)

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