Prognostic Marker In Triple Negative Breast Cancer Research Articles

Prognostic value of CD8\u2009+\u2009PD-1+ immune infiltrates and PDCD1 gene expression in triple negative breast cancer

The role of programmed cell death protein-1 (PD-1)/programmed cell death ligand 1 (PD-L1) in triple negative breast cancer (TNBC) remains to be fully understood. In this study, we investigated the role of PD-1 as a prognostic marker for TNBC in an Asian cohort (n = 269). Samples from patients with TNBC were labeled with antibodies against PD-L1 and PD-1, and subjected to NanoString assays to measure the expression of immune-related genes. Associations between disease-free survival (DFS), overall survival (OS) and biomarker expression were investigated. Multivariate analysis showed that tumors with high PD-1+ immune infiltrates harbored significantly increased DFS, and this increase was significant even after controlling for clinicopathological parameters (HR 0.95; P = 0.030). In addition, the density of cells expressing both CD8 and PD-1, but not the density of CD8−PD-1+ immune infiltrates, was associated with improved DFS. Notably, this prognostic significance was independent of clinicopathological parameters and the densities of total CD8+ cell (HR 0.43, P = 0.011). At the transcriptional level, high expression of PDCD1 within the tumor was significantly associated with improved DFS (HR 0.38; P = 0.027). In line with these findings, high expression of IFNG (HR 0.38; P = 0.001) and IFN signaling genes (HR 0.46; p = 0.027) was also associated with favorable DFS. Inclusion of PD-1 immune infiltrates and PDCD1 gene expression added significant prognostic value for DFS (ΔLRχ2 = 6.35; P = 0.041) and OS (ΔLRχ2 = 9.53; P = 0.008), beyond that provided by classical clinicopathological variables. Thus, PD-1 mRNA and protein expression status represent a promising, independent indicator of prognosis in TNBC.

Correction: The prognostic significance of combined androgen receptor, E-Cadherin, Ki67 and CK5/6 expression in patients with triple negative breast cancer.

[This corrects the article DOI: 10.18632/oncotarget.20293.].

FBXL14 abolishes breast cancer progression by targeting CDCP1 for proteasomal degradation.

Understanding the molecular mechanisms that underlie the aggressive behavior and relapse of breast cancer may help in the development of novel therapeutic interventions. CUB-domain-containing protein 1 (CDCP1), a transmembrane adaptor protein, is highly maintained and required in the context of cellular metastatic potential in triple-negative breast cancer (TNBC). For this reason, gene expression levels of CDCP1 have been considered as a prognostic marker in TNBC. However, not rarely, transcript levels of genes do not reflect always the levels of proteins, due to the post-transcriptional regulation. Here we show that miR-17/20a control the FBXL14 E3 ligase, establishing FBXL14 as an upstream regulator of the CDCP1 pathway. FBXL14 acts as an novel interaction partner of CDCP1, and facilitates its ubiquitination and proteasomal degradation with an enhanced capacity to suppress CDCP1 protein stability that eventually prevents CDCP1 target genes involved in breast cancer metastasis. Our findings first time uncovers the regulatory mechanism of CDCP-1 protein stabilization, more predictable criteria than gene expression levels for prognosis of breast cancer patients.

Nuclear Insulin-Like Growth Factor Binding Protein-3 As a Biomarker in Triple-Negative Breast Cancer Xenograft Tumors: Effect of Targeted Therapy and Comparison With Chemotherapy

Triple-negative breast cancer (TNBC) typically has a worse outcome than other breast cancer subtypes, in part owing to a lack of approved therapeutic targets or prognostic markers. We have previously described an oncogenic pathway in basal-like TNBC cells, initiated by insulin-like growth factor binding protein-3 (IGFBP-3), in which the epidermal growth factor receptor (EGFR) is transactivated by sphingosine-1-phosphate (S1P) resulting from sphingosine kinase (SphK)-1 activation. Oncogenic IGFBP-3 signaling can be targeted by combination treatment with the S1P receptor modulator and SphK inhibitor, fingolimod, and the EGFR kinase inhibitor, gefitinib (F + G). However, the interaction of this treatment with chemotherapy has not been documented. Since we observed nuclear localization of IGFBP-3 in some TNBC tumors, this study aimed to evaluate the prognostic significance of nuclear IGFBP-3 in pre-clinical models of basal-like TNBC treated with F + G and doxorubicin. Orthotopic xenograft tumors were grown in nude mice from the human basal-like TNBC cell lines MDA-MB-468 and HCC1806, and were treated with gefitinib, 25 mg/Kg, plus fingolimod, 5 mg/Kg, 3-times weekly. In some studies, doxorubicin was also administered once weekly for 6 weeks. Tumor tissue proteins were quantitated by immunohistochemistry (IHC). Interaction between doxorubicin and F + G was also studied in proliferation assays in vitro. In both tumor models, tissue staining for IGFBP-3 was predominantly nuclear. Combination of F + G significantly enhanced mouse survival, decreased nuclear IGFBP-3 and Ki67 staining, and increased apoptosis (cleaved caspase-3) staining. Kaplan–Meier survival analysis showed that a high tumor IGFBP-3 IHC score (>median), like a high Ki67 score, was significantly associated with shorter survival time, whereas a high apoptosis score was associated with prolonged survival. Studied in vitro in both cell lines, low-dose doxorubicin that had little effect alone, strongly enhanced the cytostatic effect of low-dose F + G combination. However, in both in vivo models, doxorubicin at maximum-tolerated dose neither inhibited tumor growth when administered alone, nor enhanced the significant inhibitory effect of F + G. We conclude that doxorubicin may not add benefit to the inhibitory effect of F + G unless its dose-limiting toxicity can be overcome. Nuclear IGFBP-3 appears to have potential as a prognostic marker in TNBC and could be evaluated for clinical utility.

Prognostic significance of CD117 expression and TP53 missense mutations in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is extremely aggressive and associated with poor prognosis. There are no known predictive or prognostic markers for TNBC. Inhibition of tumor protein P53 (TP53) has been demonstrated to increase the levels of cluster of differentiation 117 (CD117) in human colorectal cancer cells. However, the function of TP53 in the regulation of CD117 in TNBC has, to the best of our knowledge, not been reported. In the present study, the association between the expression of CD117 protein and TP53 mutations was investigated, and their prognostic value in patients with TNBC was assessed. A total of 58 TNBC and 48 non-TNBC breast cancer tissue samples were assessed for the expression of CD117, p53 and TP53 mutations. The marker of proliferation Ki-67 (MKI67) proliferation index and vascular invasion index (obtained by measuring D2-40 and CD34) was investigated via immunohistochemistry, and mutations in exons 4–8 of TP53 were measured using direct sequencing. Associations between CD117 and p53 levels or TP53 mutations and clinical parameters were statistically evaluated. The rates of CD117 or MKI67 positivity, CD117+/TP53 missense mutation+, TP53 missense mutations or recurrence were significantly higher in patients with TNBC than in patients with non-TNBC. In TNBC tissues, the presence of CD117 was associated with TP53 missense mutations (P=0.031), vascular invasion, recurrence and MKI67. CD117+/TP53 missense mutation+ also associated with vascular invasion, recurrence and MKI67. Under univariate analysis, MKI67, vascular invasion, CD117, CD117+/TP53 missense mutation+ and TP53 missense mutations were associated with the overall survival of patients with TNBC. Multivariate analysis revealed that vascular invasion and CD117+/TP53 missense mutation+ in primary tumors were independent prognostic factors in patients with TNBC. In conclusion, CD117+/TP53 missense mutation+ was associated with MKI67, vascular invasion and tumor recurrence in TNBC. The presence of CD117 and TP53 missense mutations together in the primary tumors was an independent prognostic factor for survival of patients with TNBC.

The prognostic significance of combined androgen receptor, E-Cadherin, Ki67 and CK5/6 expression in patients with triple negative breast cancer.

BackgroundTriple Negative Breast Cancer (TNBC) represents a heterogeneous group of tumors with poor prognosis owing to aggressive tumor biology and lack of targeted therapies. No clear prognostic biomarkers have been identified to date for this subgroup.Materials and MethodsIn this retrospective study we evaluated the prognostic role of 4 different molecular determinants, including androgen receptor (AR), E-cadherin (CDH1), Ki67 index, and basal cytokeratins (CKs) 5/6, in a cohort of 99 patients with TNBC. All patients received neo/adjuvant chemotherapy (mostly anthracycline/taxane-based). Immunohistochemistry (IHC) was performed in formalin-fixed paraffin-embedded primary tumor samples. CDH1 expression was considered positive as ≥ 30% of the membrane cells staining. AR positivity was defined as > 10% of positive tumor cells. High Ki67 was defined as ≥20% positive tumor cells. CK5/6 expression was judged positive if the score was ≥1.ResultsThe absence of AR expression was significantly associated with highly undifferentiated tumors. Univariate analyses showed that lack of expression of CDH1, tumor size and nodal status were significantly correlated with worse RFS and OS (p< 0.05). AR expression and low Ki67 showed a trend towards better RFS and OS. Patients with absent CK5/6 expression in univariate and multivariate analyses had poorer RFS (p=0.02 and p=0.002, respectively) and OS (p=0.05 and p=0.02, respectively). Multivariate analysis showed an independent association between CDH1 expression and better RFS and OS (p< 0.05) beyond tumor size, nodal status, and grade. The Kaplan-Meier curves showed that patients with AR and CDH1 negative expression and high Ki-67 levels have a significant correlation with poor outcome.ConclusionsOur study supports the use of IHC expression of AR, CDH1, Ki67, and CK5/6 as prognostic markers in TNBCs and suggests a link between their expression and prognosis and may help to stratify TNBC patients in different prognostic classes.

Dynamic relationship between cycling kinetics of triple-negative breast cancer and tumor infiltrating immune cells.

1100 Background: Recent studies show strong correlation between tumor infiltrating lymphocytes (TILs) and triple-negative breast cancer (TNBC) patient survival. CD8+ T cells serve as a favorable prognostic marker for TNBC. In addition, other cells such as CD4+ T cells, macrophages, B cells, and Tregs also infiltrate tumors. In this study, we delineate a strong relationship between the cycling kinetics of proliferating cells in TNBCs and antitumor immune response. Methods: A multi-institutional study performed by our group has previously shown that KAMS (Ki67-Adjusted Mitotic Score) provides a measure of the cycling kinetics of proliferating tumor cells and robustly stratifies TNBC patients into slow cycling (low KAMS) cyclophosphamide-methotrexate-fluorouracil (CMF)-responsive and fast cycling (high KAMS) CMF-resistant subgroups. In this study, we reviewed clinical data from 124 CMF-treated TNBC patients from Nottingham Hospital and sought correlations between cycling kinetics (High/Low KAMS) and tumor infiltrating immune cells. Results: We found that slow cycling TNBCs had higher mean expression of tumor infiltrating immune cells than fast cycling TNBCs. Intratumoral CD68 (p = 0.003), CD3 (p = 0.006), CD20 (p = 0.01), FOXP3 (p = 0.01), and total numbers of intratumoral and stromal CD68 (p = 0.01) and CD3 (p = 0.03) expressing cells were found to be significantly higher in low KAMS tumors than in high KAMS tumors. Of these biomarkers, CD68 was significantly associated with patients’ breast cancer-specific survival (BCSS): (a) low KAMS, high CD68 TNBCs had better BCSS than low KAMS, low CD68 (p = 0.01) TNBCs, and (b) high KAMS, low CD68 cases had better BCSS than high KAMS, high CD68 cases. Conclusions: Our observation that there are more TILs in slow cycling TNBCs suggests that there may be a dynamic cross-regulation between cycling kinetics and antitumor immune response. From our surprising observation that CD68 exerts polar roles in low/high KAMS subgroups, we propose that distinctions in M1 and M2 macrophage subsets in slow and fast cycling TNBCs may correlate with distinct outcomes. In addition, metabolic competition between tumor and immune cells may determine the level and function of TILs.

P53 and Ki-67 as prognostic markers in triple-negative breast cancer patients.

Triple-negative breast cancer (TNBC) is an aggressive subgroup of breast cancer lack of effective target therapy. This study was to investigate the prognostic role of p53 and Ki-67 in 156 cases of TNBC patients. Logistic regression analysis was used to examine the association between clinical parameters and recurrence. Univariate and multivariate analyses were used to examine the association between clinical characteristics and disease-free survival (DFS) or overall survival (OS). Survival analyses using the Kaplan-Meier method were performed to examine the association between p53/Ki-67 and DFS and OS. Our data showed that p53 was positive in 71.3% and the Ki-67 high index was in 82.8% of TNBC. Elevated p53 and Ki-67 were associated with histological grade. The tumor size, lymph node involvement, and p53 expression are associated with risk of recurrence. Tumor size, lymph node involvement, family history, Ki-67 and p53 are independent variables associated with either DFS or OS. TNBC patients with positive p53 or Ki-67 high index or family history of cancer have a significant association with worse prognosis. This study suggests that p53, Ki-67 and family history are useful prognostic markers in TNBC.

Prognostic impact of EGFR and cytokeratin 5/6 immunohistochemical expression in triple-negative breast cancer.

EGFR and CK5/6 are adverse prognostic markers in TNBC. EGFR and CK5/6 expression could serve as biomarkers for identifying TNBC patients with poor survival that are unlikely to benefit from neoadjuvant chemotherapy. So, targeted therapy against EGFR may be a hopeful therapy for TNBC with NAC resistance.

An immune stratification reveals a subset of PD-1/LAG-3 double-positive triple-negative breast cancers.

BackgroundStromal tumor-infiltrating lymphocytes (TILs) are a robust prognostic factor in triple-negative breast cancer (TNBC). However, the clinical significance of TILs may be influenced by the complex landscape of the tumor immune microenvironment. In this study, we aimed to evaluate the composition and the functionality of lymphocytic infiltration and checkpoint receptors in TNBC.MethodsFormalin-fixed, paraffin-embedded tissues were retrospectively collected from a cohort of patients with early-stage TNBC treated with adjuvant anthracycline-based chemotherapy (n = 259). Results were validated in an independent cohort of patients with TNBC (n = 104). Stromal TILs were evaluated on hematoxylin-and-eosin-stained sections. The density of CD4+, CD8+, and FOXP3+ lymphocytes, and the expression of the immune checkpoints PD-1 and LAG-3, were assessed by immunohistochemical analysis.ResultsThe presence of elevated TILs positively correlated with the density of all T cell subtypes, especially cytotoxic CD8+ lymphocytes. We showed that increasing stromal TILs assessed as a continuous variable is an independent prognostic marker of prolonged relapse-free survival and overall survival in TNBC. Among immune subpopulations, CD8+ lymphocytes are the main effectors of anti-tumor immune responses. In two independent cohorts, we found that PD-1 and LAG-3 were concurrently expressed in approximately 15% of patients with TNBC. The expression of both checkpoint receptors positively correlated with the presence of TILs, but was not significantly associated with patient outcome.ConclusionsOverall, our data indicate that the evaluation of stromal TILs remains the most reliable immune prognostic marker in TNBC, and support the clinical evaluation of anti-PD-1/PD-L1 and anti-LAG-3 in a subset of patients with TNBC who have concurrent expression of both checkpoint receptors.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-016-0783-4) contains supplementary material, which is available to authorized users.

Coexistent Loss of the Expressions of BRCA1 and p53 Predicts Poor Prognosis in Triple-Negative Breast Cancer.

To investigate the prognostic significance of altered breast cancer susceptibility gene 1 (BRCA1) and p53 expression in triple-negative breast cancer (TNBC). Immunohistochemical expression of BRCA1 and p53 was examined in the tumor tissues of 465 TNBC cases and relations were sought with clinicopathological features and patient survival. Loss of BRCA1 expression was found in 29.5% (137/465) of TNBCs. Positive expression of p53 was observed in 49.9% (232/465). Patients with loss of BRCA1 expression had a tendency to have higher rate of lymph node metastasis (p=0.075). An association between p53 expression and high histological grade was observed (p=0.039). TNBC patients with loss of BRCA1 expression had a tendency to have poorer overall survival (OS) than those positive for BRCA1 (p=0.09). TNBC patients with positive p53 expression showed better OS than those with p53 negativity (p=0.001). In terms of combined expression patterns, significantly poorer overall survival (OS) was observed for BRCA1-negative/p53-negative TNBCs and best OS for BRCA1-positive/p53-positive TNBCs (p=0.005). Combined expression patterns of BRCA1 and p53 could serve as useful prognostic markers in TNBC.

Steroid Receptor Coactivator-3 (SRC-3/AIB1) as a Novel Therapeutic Target in Triple Negative Breast Cancer and Its Inhibition with a Phospho-Bufalin Prodrug.

Triple negative breast cancer (TNBC) has the poorest prognosis of all types of breast cancer and currently lacks efficient targeted therapy. Chemotherapy is the traditional standard-of-care for TNBC, but is frequently accompanied by severe side effects. Despite the fact that high expression of steroid receptor coactivator 3 (SRC–3) is correlated with poor survival in estrogen receptor positive breast cancer patients, its role in TNBC has not been extensively investigated. Here, we show that high expression of SRC–3 correlates with both poor overall survival and post progression survival in TNBC patients, suggesting that SRC–3 can serve as a prognostic marker for TNBC. Furthermore, we demonstrated that bufalin, a SRC–3 small molecule inhibitor, when introduced even at nM concentrations, can significantly reduce TNBC cell viability and motility. However, because bufalin has minimal water solubility, its in vivo application is limited. Therefore, we developed a water soluble prodrug, 3-phospho-bufalin, to facilitate its in vivo administration. In addition, we demonstrated that 3-phospho-bufalin can effectively inhibit tumor growth in an orthotopic TNBC mouse model, suggesting its potential application as a targeted therapy for TNBC treatment.

Androgen Receptor (AR), E-Cadherin, and Ki-67 as Emerging Targets and Novel Prognostic Markers in Triple-Negative Breast Cancer (TNBC) Patients.

BackgroundTNBC is an aggressive subset of breast cancer (BC) without specific target therapy.MethodsThis observational, retrospective study included 45 cases of TNBC. The aim of this study was to evaluate the expression of the AR, E-cadherin and Ki-67 in relation to histological type, time to relapse and overall survival (OS). Immunohistochemistry (IHC) was carried out on formalin-fixed paraffin-embedded tumor samples obtained from patients defined TNBC.ResultsThe AR was positive (IHC >10%) in 26.6%. E-cadherin (CDH1) expression was considered positive if the score was ≥ 2. This expression was negative in 53.3% cases. The Ki-67 index was ≥ 20% in 37.7%. Univariate analyses showed that AR, CDH1 and Ki-67 are significantly associated with OS. Multivariate analysis showed that AR and Ki-67 expression are independent variables associated with OS. The statistical analysis showed that patients with AR negative and Ki-67 positive expression have a significant correlation with poor outcome.ConclusionsOur data suggest that the combination of AR and E-cadherin expression as well as Ki-67 status might be useful prognostic markers in TNBC. Hence, these molecular determinants could play an interesting role to classify subgroups of TNBC.

Tumor infiltrating CD8+ T lymphocyte count is independent of tumor TLR9 status in treatment naïve triple negative breast cancer and renal cell carcinoma

Toll-like receptor 9 (TLR9) is a cellular DNA-receptor of the innate immune system that is widely expressed in cancers. We demonstrated that low tumor TLR9 expression predicts poor disease-specific survival in triple negative breast cancer (TNBC) and renal cell carcinoma (RCC). We hypothesized that this is because TLR9 expression affects tumor immunophenotype. To begin to test this, we compared the number of tumor infiltrating CD8+ T lymphocytes with TLR9 expression in treatment naïve breast cancer (n = 197) and RCC (n = 94) cohorts with known TLR9 expression status. CD8+ T lymphocyte counts were assayed with image analysis after immunohistochemistry (IHC). Tumor TLR9 expression was not correlated with CD8+ T cell counts in breast cancer or RCC. CD8+ T cell counts were significantly associated with tumor proliferation index in TNBC, but not in non-TNBC. CD8+ T cell counts were also significantly associated with tumor grade in non-TNBC, but not in TNBC. In RCC, CD8+ T cell counts were significantly associated with tumor stage. CD8+ T cell counts were significantly associated with prognosis in TNBC and RCC, but the presence of CD8+ T cells in these tumors had opposite effects on disease-specific survival: High CD8+ counts were associated with better prognosis in TNBC and worse prognosis in RCC. Among TNBC patients, those with low tumor TLR9 and low CD8+ T cell counts had the poorest prognosis (log-rank p = 0.0002 vs. high tumor TLR9 and high CD8+ T cell count). In conclusion, pre-treatment tumor TLR9 status is not associated with tumor infiltrating CD8+ T lymphocytes in TNBC or RCC. The combination of TLR9 and CD8+ TIL count might be a novel composite prognostic marker in TNBC.

Triple negative breast cancer - BCL2 in prognosis and prediction. Review.

Breast cancer (BC), the most frequent malignancy in women worldwide, is currently diagnosed in about 1.4 million female patients annually. Approximately 10-20% of BC is represented by triple negative breast cancer (TNBC) which is aggressive, the prognosis is poor and patients cannot benefit from targeted treatment based on hormonal or HER2 receptors. For this reason, search for markers that can predict the efficacy of chemotherapy in TNBC is a priority. This review focuses on BCL2 protein as a prognostic marker in TNBC and its potential as a predictor of sensitivity to chemotherapy. BCL2 protein expression is a positive prognostic factor in BC. Better survival of patients with BCL2 positivity (BCL2+) has been explained by the correlation with estrogen receptor positive (ER+) status. BCL2+ is however not simply a surrogate marker for ER+. Moreover, BCL2 protein expression is also a positive prognostic marker in the TNBC subgroup. We and others show, that low BCL2 expression was associated with good outcome of TNBC patients treated with both adjuvant and neoadjuvant anthracycline-based chemotherapy. On the other hand, recent studies have shown that a subset of TNBC patients may benefit from the classical adjuvant CMF (cyclophosphamide, methotrexate, 5-fluorouracil) regimen. Given the heterogeneity of TNBC there is an urgent need to find and validate the sensitivity predictors to these regimens making them usable in clinical practice. BCL2 enrichment has been described in the mesenchymal stem-like (MSL) TNBC subgroup.

Androgen receptor (AR), E-cadherin, and Ki-67 as prognostic markers in triple-negative breast cancer (TNBC).

1062 Background: TNBC is an aggressive subset of breast cancer (BC) with central nervous system and visceral metastatic involvement and it represents a molecular subtype without specific target therapy. Methods: This observational, retrospectivestudy included 45 TNBC. The aim of this study was to evaluate the expression of some molecular determinants such as the AR, E-cadherin and Ki-67 in relation to histological type, time to relapse and overall survival.Immunohistochemistry (IHC) was carried out on formalin-fixed paraffin-embedded tumor samples obtained from patients (pts) defined TNBC, since ER and PgR were 0% and HER2 negative (IHC score 0/1 or FISH not amplified). Results: Median age was 58.8 years (range 39-77). The main histological type was ductal in 35 pts (77.7%), lobular in 7 (15.5%), medullary in 3(6.6%). 29 pts (64.4%) had a G3 tumor. Tumor stage was: I 6/45 (13.3%), IIA 21/45 (46.6%), IIIA 11/45 (24.4%), IIIB 3/45 (6.6%) and IV 4/45 (8.8%). All patients received treatments; the most frequently used regimens were anthracycline and taxanes. The androgen receptor was positive (IHC &gt;10%) in 12/45 (26.6%). E-cadherin expression was semi-quantitatively analyzed according to the percentage of cells showing membrane positivity: 0 (0 to 10%); 1+ (10 to 30%); 2+ (30 to 70%); 3+ (&gt; 70%). E-cadherin expression was considered positive if the score was ≥ 2, and negative when score was ≤ 1. This expression was negative in 24/45 (53.3%) cases. The Ki-67 index was ≥ 25% in 17/45(37.7%). The statistical analysis showed that patients with AR negative and Ki-67 positive expression have a significant correlation with the ductal histotype and G3 tumors (p &lt; 0.001). Multivariate analysis showed that the patients with AR and E-cadherin negative but Ki-67 positive expression showed significantly (p &lt; 0.001) worse overall survival time than those with either AR and E-cadherin positive but Ki-67 negative expression. Conclusions: Our data suggest that the combination of AR and E-cadherin expression as well as Ki-67 status might be useful prognostic markers in TNBC.

High ERK Protein Expression Levels Correlate with Shorter Survival in Triple-Negative Breast Cancer Patients

The mitogen-activated protein kinase (MAPK) signaling pathway is known to be activated in triple-negative breast cancer (TNBC). Extracellular signal-related kinase (ERK), a member of the MAPK pathway, promotes cell proliferation, angiogenesis, cell differentiation, and cell survival. To assess the prognostic impact of ERK in TNBC patients, relative quantities of ERK (ERK-2 and pMAPK) and direct targets of the ERK pathway (MAPK/ERK kinase 1, phospho-enriched protein in astrocytes [PEA]-15, phosphorylated (p)PEA-15, tuberous sclerosis protein 2, p70S6 kinase, and p27) were measured using reverse-phase protein arrays in tumor tissue from patients with TNBC (n = 97) and non-TNBC (n = 223). Protein levels in patients with TNBC were correlated with clinical and tumor characteristics and outcome. The median age of patients with TNBC was 55 years (range, 27-86 years). Disease stage was I in 21%, II in 60%, and III in 20% of the patients. In a multivariate analysis, among patients with TNBC, those with ERK-2-overexpressing tumors had a lower overall survival rate than those with low ERK-2-expressing tumors (hazard ratio [HR], 2.76; 95% confidence interval [CI], 1.19-6.41). However, high pMAPK levels were associated with a significantly higher relapse-free survival rate (HR, 0.66; 95% CI, 0.46-0.95). In conclusion, ERK-2 and pMAPK are valuable prognostic markers in TNBC. Further studies are justified to elucidate ERK's role in TNBC tumorigenicity and metastasis.