BERKELEY, CA (UroToday.com) - Cancer metastasis accounts for the majority of cancer-related deaths owing to poor response to anticancer therapies.[1] Molecular understanding of metastasis-associated drug resistance remains elusive owing to the scarcity of available tumor tissue. Isolation of circulating tumor cells (CTCs) from the peripheral blood of patients has emerged as a valid alternative source of tumor tissue that can be subjected to molecular characterization.[2, 3, 4] However, issues with low purity and sensitivity have impeded adoption to clinical practice.[5, 6]
Here we report a novel method to capture and molecularly characterize CTCs isolated from castrate-resistant prostate cancer patients (CRPC) receiving taxane chemotherapy. We have developed a geometrically enhanced differential immunocapture (GEDI) microfluidic device that combines an anti-prostate specific membrane antigen (PSMA) antibody with a 3D geometry that captures CTCs and minimizes nonspecific leukocyte adhesion.[7] Enumeration of GEDI-captured CTCs (defined as intact, nucleated PSMA+/CD45− cells) revealed a median of 54 cells per ml identified in CRPC patients versus 3 in healthy donors. Direct comparison with the commercially available CellSearch® revealed a 2–400 fold higher sensitivity achieved with the GEDI device.[8] Confocal microscopy of patient-derived GEDI-captured CTCs identified the TMPRSS2:ERG fusion protein,[9] and sequencing identified a specific androgen receptor point mutation (T868A) [10] in blood samples spiked with only 50 PC C4-2 cells. On-chip treatment of patient-derived CTCs with docetaxel and paclitaxel allowed monitoring of drug-target engagement by means of microtubule bundling.[11, 12, 13, 14] CTCs isolated from docetaxel-resistant CRPC patients did not show any evidence of drug activity.
These measurements constitute the first functional assays of drug-target engagement in living, circulating tumor cells and therefore have the potential to enable longitudinal monitoring of target response and inform the development of new anticancer agents.
References:
- Maheswaran, S. and D. A. Haber (2010). "Circulating tumor cells: a window into cancer biology and metastasis." Current Opinion in Genetics & Development 20(1): 96-99.
- Racila, E., D. Euhus, et al. (1998). "Detection and characterization of carcinoma cells in the blood." Proceedings of the National Academy of Sciences 95(8): 4589-4594.
- Zieglschmid, V., C. Hollmann, et al. (2005). "Detection of disseminated tumor cells in peripheral blood." Critical Reviews in Clinical Laboratory Sciences 42(2): 155-196.
- Pantel, K., R. H. Brakenhoff, et al. (2008). "Detection, clinical relevance and specific biological properties of disseminating tumour cells." Nat Rev Cancer 8(5): 329-340.
- Riethdorf, S. and K. Pantel (2010). "Advancing personalized cancer therapy by detection and characterization of circulating carcinoma cells Circulating tumor cells in cancer patients Riethdorf & Pantel." Annals of the New York Academy of Sciences 1210(1): 66-77.
- Pratt, E. D., C. Huang, et al. (2011). "Rare cell capture in microfluidic devices." Chemical Engineering Science 66(7): 1508-1522.
- Gleghorn, J. P., E. D. Pratt, et al. (2010). "Capture of circulating tumor cells from whole blood of prostate cancer patients using geometrically enhanced differential immunocapture (GEDI) and a prostate-specific antibody." Lab on a chip 10(1): 27-9.
- Danila, D. C., G. Heller, et al. (2007). "Circulating tumor cell number and prognosis in progressive castration-resistant prostate cancer." Clinical cancer research : an official journal of the American Association for Cancer Research 13(23): 7053-8.
- Tomlins, S. A., D. R. Rhodes, et al. (2005). "Recurrent Fusion of TMPRSS2 and ETS Transcription Factor Genes in Prostate Cancer." Science 310(5748): 644-648.
- Veldscholte, J., C. Ris-Stalpers, et al. (1990). "A mutation in the ligand binding domain of the androgen receptor of human INCaP cells affects steroid binding characteristics and response to anti-androgens." Biochemical and Biophysical Research Communications 173(2): 534-540.
- Petrylak, D. P., C. M. Tangen, et al. (2004). "Docetaxel and Estramustine Compared with Mitoxantrone and Prednisone for Advanced Refractory Prostate Cancer." New England Journal of Medicine 351(15): 1513-1520.
- Tannock, I. F., R. de Wit, et al. (2004). "Docetaxel plus Prednisone or Mitoxantrone plus Prednisone for Advanced Prostate Cancer." New England Journal of Medicine 351(15): 1502-1512.
- Marcus, A. I., U. Peters, et al. (2005). "Mitotic Kinesin Inhibitors Induce Mitotic Arrest and Cell Death in Taxol-resistant and -sensitive Cancer Cells." Journal of Biological Chemistry 280(12): 11569-11577.
- de Bono, J. S., S. Oudard, et al. (2010). "Prednisone plus cabazitaxel or mitoxantrone for metastatic castration-resistant prostate cancer progressing after docetaxel treatment: a randomised open-label trial." The Lancet 376(9747): 1147-1154.
Written by:
Steven M. Santanaa and Brian J. Kirbya, b as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
aSibley School of Mechanical and Aerospace Engineering, Ithaca, NY 14850 USA
bDepartment of Medicine, Division of Hematology and Oncology, Weill-Cornell Medical College, New York, NY 10065 USA
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