High sensitivity multiparameter method for rare event analysis in a biological sample
A sample of blood containing CTCs, or other cells of interest, is stained with fluorescent markers for image analysis and scanned to identify the presence and location within the cartridge of target cells or subcellular elements. A sample containing desired target cells or subcellular elements is then further processed, in part by photobleaching the sample, so that those same targets may be re-analyzed with additional biomarkers conjugated to the same or different fluorochromes using the same imaging criteria that were used for the initial analysis. The present invention has applications with targets such as circulating epithelial, cells, circulating tumor cells, circulating endothelial cells, leukocytes, lymphocyte subsets, cells containing an organelle or receptor of interest, cellular debris, disrupted cells and their debris, or any other formed element that might be captured and imaged. The invention provides a means to further interrogate individual targets of interest, especially when coupled with genetic analysis such as FISH.
1. A method for confirming the detection and enumeration of circulating tumor cells in a mixed cell population, comprising:
a. obtaining a biological specimen from a test subject, said specimen comprising the mixed cell population suspected of containing said circulating tumor cells;
b. isolating said circulating tumor cells by immunomagnetic enrichment;
c. identifying said circulating tumor cells by a multiparametric profile analysis where said profile is obtained through steps comprising:
i. labeling said circulating tumor cells with a first fluorescent marker, wherein the fluorescent labeled marker comprises a label of a high sensitivity fluorophore and a first marker that has a low concentration on said circulating cells;
ii. scanning said circulating tumor cells;
iii. aspirating the fluid from said circulating cells wherein said aspirating fixes said circulating cells in position on an imaging surface;
iv. photobleaching the fluorescently labeled circulating tumor cells of step (i) using light-emitting diodes;
v. labeling said circulating tumor cells in step (iv) with a second fluorescent labeled marker wherein said second fluorescent labeled marker comprises the same label of step (i) and a second marker wherein the second marker has a low concentration in said circulating tumor cell; and
vi. rescanning said fluorescently labeled circulating tumor cells of step (v); and
d. confirming said circulating tumor cells when the first and second fluorescent labeled markers are associated with the circulating tumor cells.
2. The method of claim 1 wherein said profile analysis is genotypic.
3. The method of claim 1 where said profile analysis is phenotypic.
4. The method of claim 1 wherein said label comprising the high sensitivity fluorophore is phycoerythrin.
5. The method of claim 1 wherein said first marker that has a low concentration is insulin like growth factor-1 receptor (IGF-1R).
6. The method of claim 1 wherein said second marker that has a low concentration is kinase important in cell signaling (p-AKT).