Blood test to monitor the genetic changes of progressive cancer using immunomagnetic enrichment and fluorescence in situ hybridization (FISH)
Amplification and overexpression of theHER-2 oncogene in breast cancer is felt to be stable over the course of disease and concordant between the primary tumor and metastases. Therefore, patients with HER-2 negative primary tumors will rarely receive anti-HER-2 antibody therapy. A very sensitive blood test is used to capture circulating tumor cells (CTC's) and evaluate their HER-2 gene status by FISH evaluation. The HER-2 status of the primary tumor and corresponding CTC's is used to assess the ratio of CTC's as a reliable surrogate marker. HER-2 expression of 10 CTC's is sufficient to make a definitive diagnosis of the HER-2 gene status for the whole population of CTC's in patients with recurrent breast cancer.
1 . A method for assessing individual patient response to anti-HER-2 therapy comprising:
a) obtaining a biological specimen from diagnosed with metastatic breast cancer, said specimen comprising a mixed cell population suspected of containing rare cells;
b) immunomagnetically enriching a fraction of said specimen, said fraction containing said rare cells;
c) confirming at least HER-2 protein expression in said rare cells by immunofluorescence;
d) quantitating at least HER-2 gene expression in said rare cells by FISH; and
e) correlating said gene expression and said protein expression with rare cell count to predict therapeutic response based upon a predetermined statistical association.
2 . A method as claimed in claim 1 , wherein said fraction is obtained by immunomagnetic enrichment of colloidal paramagnetic particles, coupled to a biospecific ligand which specifically binds to said rare cells, to the substantial exclusion of other populations.
3 . A method as claimed in claim 2 , wherein said rare cells are immunomagnetically enriched with antibodies to the epithelial cell surface antigen EPCAM.
4 . A method as claimed in claim 1 , wherein HER-2 and CEP17 are DNA probes used in said FISH.
5 . A method as claimed in claim 1 , wherein said correlating is a statistical comparison of the immunofluoresent intensity of said anti-HER-2 protein expression and said FISH in said rare cells.
6 . A method as claimed in claim 1 whereby said correlating provides phenotypic and genotypic information of said rare cells for assessing therapy in patients.