Background:
Circulating Tumor Cells (CTCs) present in each subtype may represent distinct metabolic
profiles for survival, metastatic spread and therapy resistance. Using a multi-marker
gene panel for the characterization of CTCs, we here compared the genetic profiles
of CTCs in triple-negative BC (TNBC) and non-TNBC patients (pts).
Methods:
52 TNBC and non-TNBC pts. (41 = HER2-/HR+; 11 = HER2+/HR-) before and/or after neoadjuvant
therapy were analyzed for CTCs, applying positive immunomagnetic selection targeting
EpCAM, EGFR and HER2 using the AdnaTest EMT-2/Stem Cell Select (QIAGEN, Hilden, Germany).
Subsequently, cDNA was gene specifically pre-amplified using TaqMan PreAmp Master
Mix according to in house designed assays. Multiplex RT-qPCR was performed for 19
genes, GAPDH and CD45 served as reference genes. The cutoff was calculated as Ct(cutoff)-Ct(sample)-[Ct(CD45cutoff)-Ct(CD45sample)],
taking into account the false positive rate in healthy donors.
Results:
In TNBC pts, all the different genes were expressed, representing the most heterogeneous
CTC population. HER2+/HER3+CTCs were found at both time points in more than 20% of
the pts. Before therapy, the androgen receptor (AR) and EGFR were present in CTCs
of 35% and 23% of the pts. 67% of the genes were expressed before and after therapy
(mainly ERBB-family and PI3K pathway). A reduced DFS in TNBC pts seems to be related
to the presence of HER2+/HER3+/EGFR+CTCs before and after therapy and to platinum-based-therapy,
which induced PI3K expression in CTCs after therapy, resulting in the expression of
genes related to resistance.
Conclusion:
This knowledge might efficiently help to predict a personalized targeted therapy for
these pts in the future.
