Introduction. Several studies have applied gene expression profiling to inflammatory breast cancer (IBC). Most of these studies were underpowered. Here, we present an integrated analysis of 3 distinct gene expression data sets of IBC and non-IBC (nIBC) samples to further uncover the IBC-specific molecular biology with enhanced statistical power. Materials & Methods. Three Affymetrix gene expression data sets were combined, resulting in a series of 137 IBC and 252 nIBC samples. IBC was diagnosed clinically. Each sample was classified according to several published gene signatures. Transcriptional heterogeneity was investigated using hierarchical clustering, coupled with silhouette score analysis. IBC-specific, molecular subtype-independent differences in gene expression were identified using linear regression modeling. Differentially expressed genes were translated into pathways using Ingenuity Pathway Analysis. Cox regression analysis was used to identify variables influencing distant metastasis-free survival (DMFS) in IBC. Finally, we focussed on the molecular aspects of pathological response to neodjuvant chemotherapy in patients with IBC. Results. In our series of IBC samples, 4 robust sample clusters were identified. These sample clusters were mainly associated with the different molecular subtypes (P<0.0001), all of which were identified in IBC with a similar prevalence in nIBC, except for the Luminal A subtype (9% vs. 40%; P<0.0001) and the ErbB2+ subtype (23% vs. 8%; P=0.0002). A total of 632 genes were differentially expressed. Analysis of this gene list identified an IBC-repressed network centered on TGFβ. Activated TGFβ-profiles and SMAD-profiles in the nIBC samples corroborated these findings. Consistent with published poor prognosis signatures, current survival analysis indicated that the molecular subtypes are significantly associated with prognosis in IBC. Surprisingly, in IBC, the Luminal A samples exhibited the shortest DMFS-interval (HR=4.02; P<0.05). Comparison of responders and non-responders to neoadjuvant chemotherapy suggests a prominent role for inflammation/immunity-related processes in determining the efficacy of neoadjuvant chemotherapy in IBC. Conclusions. IBC, like nIBC, is transcriptionally heterogeneous as exemplified by the identification of 4 robust sample clusters in the present series. This observation is further corroborated by the identification of all known molecular subtypes in IBC, albeit with a different distribution pattern characterized by a low frequency of Luminal A samples. Nevertheless, this phenotype is clinically relevant, as demonstrated by the poor prognosis profile. Our observations can be explained by the IBC-specific repression of TGFβ, which is a key molecule of epithelial-to-mesenchymal transition and is also known to prevent ER-expressing cells from proliferating. Finally, as in nIBC, inflammation- and immunity-related processes are important aspects of response to neoadjuvant chemotherapy in IBC. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD03-01.
Introduction: The enumeration of CTCs has already shown to bear clinical relevance as a prognostic and predictive factor in metastatic breast cancer. In addition to enumeration, isolation of CTCs enables their molecular characterization and thus holds great promise to establish association of their genetic profile with patient outcome and to identify potential drugable targets. In this study we established epithelial-specific mRNA and microRNA profiles in CTCs of patients with metastatic breast cancer, compared these profiles to the profiles measured in corresponding primary tumors, and determined their association with clinical parameters. Study design: For this study we included 50 breast cancer patients, of which 32 presented themselves with over 5 CTCs at the time of metastatic disease. From 14 of these patients with more than 5 CTCs at the time of metastatic disease also the primary tumor at time of breast cancer diagnosis was evaluated. Total RNA was extracted 1) from blood of the 50 patients with metastatic disease after EpCAM-based enrichment of 7.5 mL whole blood with the CellSearch™ Profile Kit [Veridex LCC], 2) from 14 unprocessed whole blood preparations from healthy blood donors, and 3) from 14 primary tumors. Gene transcript levels of CTC-specific and potentially clinically relevant mRNAs and microRNAs were compared in CTCs isolated at time of metastatic disease and the corresponding primary tumors. In addition, the association of these transcript levels with clinical data was assessed. Results: We identified 24 mRNA and 14 microRNAs more abundantly expressed in CellSearch-enriched fractions from patients with at least 5 CTCs compared with those without CTCs and/or compared with unprocessed whole blood prior to CellSearch enrichment (Mann-Whitney U-test P<0.05). In addition, when comparing transcript levels present in CTCs during metastatic disease and those measured in the corresponding primary tumor, potentially clinically relevant discrepancies were observed. Findings of interest included changes in transcript levels of genes such as ESR1, ERBB2, TOP2A and MGB1, and in genes associated with proliferation and EMT. Finally, associations were observed between transcript levels measured in CTC preparations and clinical data like nodal status and size of the primary tumor. Conclusion: Our results show that molecular characterization of CTCs is feasible and has potential for a more tailored clinical approach above CTC enumeration in the treatment of metastatic breast cancer patients. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-02-05.
Introduction: The enumeration of circulating tumour cells (CTCs) with the EPCAM-based CellSearch system has prognostic significance in patients with metastatic breast cancer (MBC). However, breast cancer has been shown to be a molecularly heterogeneous disease. The aim of this study was to assess potential differences in the detection and prognostic significance of CTCs according to the immunohistochemically defined molecular subtypes of breast cancer. Methods: CellSearch CTC counts were obtained from 110 patients with MBC prior to first line systemic treatment, treated at GZA Hospitals Sint-Augustinus between november 2007 and december 2011. Clinicopathological variables were prospectively entered in a database. Based on the St-Gallen surrogate definitions of intrinsic breast cancer subtypes (Goldhirsch et al. Ann Oncol 2011), patients were divided in 5 groups: luminal A (ER/PR+, HER2−, Bloom-Richardson histological grade I-II), luminal B – HER2 negative (ER/PR+, Her2−, grade III), luminal B – HER2 positive (ER/PR+, HER2+, any grade), HER2 positive – non luminal (ER/PR−, HER2+), and triple negative (TN) (ER/PR−, HER2−). Differences in progression free survival (PFS) and overall survival (OS) according to the FDA approved prognostic cut-off of ≥5 CTC/7.5 ml blood were estimated using Kaplan Meier and Cox proportional hazard statistics. Results: CTC were detected in 78 of 110 (71%) patients. Higher detection rates and numbers of CTC were observed in patients with luminal A and TN breast cancer as compared to patients with luminal B and HER2 positive disease. However, no differences in positivity rates were observed between molecular subtypes according to the 5 CTC prognostic cut-off point (table 1). After a median FU time of 3.1 years, 39 patients had died. In the total study population, the presence of ≥5 CTC was an independent predictor of PFS and OS in multivariate analysis (PFS: HRCTC≥5=2.236 (1.366–3.658), p = 0.001; OS: HRCTC≥5=3.180 (1.553–6.509), p = 0.002). When analyzing subgroups separately, a lower prognostic power was observed in the HER2 positive and luminal B subgroups. Conclusion: Significant differences were observed in the detection and prognostic significance of EPCAM positive CTC according to the immunohistochemically defined breast cancer subtypes. Interestingly, CTC were detected more frequently in patients with luminal A and TN tumors. Furthermore, our data suggest a lower prognostic significance of CTC evaluation in HER2 positive patients with MBC. Our data independently confirm those reported by Giordano et al. (Ann Oncol 2010) in a large clinically uniform population of patients with MBC before the start of first-line treatment. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P2-01-08.
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