PTK7 as a potential prognostic and predictive marker of response to adjuvant chemotherapy in breast cancer patients, and resistance to anthracycline drugs.

Biomarkers predicting resistance to particular chemotherapy regimens could play a key role in optimally individualized treatment concepts. PTK7 (protein tyrosine kinase 7) belongs to the receptor tyrosine kinase family involved in several physiological, but also malignant, cell behaviors. Recent studies in acute myeloid leukemia have associated PTK7 expression with resistance to anthracycline therapy. PTK7 mRNA expression in primary tumor tissue (PTT) and corresponding lymph node tissue (LNT) were retrospectively measured in 117 patients with early breast cancer; PTK7 expression was available in 103 PTT and 108 LNT samples. Median age was 60 years (range, 27-87 years). At a median follow-up of 28.5 months, 6 deaths and 16 recurrences had occurred. PTK7 expression correlations with clinicopathological features were computed and PTK7 expression effects on patient outcome were analyzed in three cohorts defined by adjuvant treatment: anthracycline-based treatment, other chemotherapy regimens (including taxane or other substances), or no chemotherapy. Association of PTK7 expression with clinicopathological features was seen only for age in PTT and nodal stage in LNT. High LN PTK7 was associated with poorer disease-free survival (DFS) in the total population (3-year DFS: low [81.7%] versus high [70.4%]; P=0.016) and in patients without adjuvant chemotherapy (3-year DFS: low [91.7%] versus high [22.3%]; P<0.001), but not in patients receiving adjuvant chemotherapy (P=0.552). DFS stratified by PTK7 expression was compared in treatment cohorts: In patients with low LN PTK7 expression, neither chemotherapy cohort showed significantly better survival than the no-chemotherapy cohort. In patients with high LN PTK7 expression, those receiving chemotherapy, including substances other than anthracyclines, but not those receiving only anthracycline-based chemotherapy, showed significantly better DFS than those receiving no chemotherapy (P=0.001). Our results support earlier findings that PTK7 may be a prognostic and predictive marker associated with resistance to anthracycline-based chemotherapy. Further investigations are needed to validate these findings in breast cancer.

Gross cystic disease fluid protein 15 (GCDFP-15) expression in breast cancer subtypes.

BACKGROUND: Gross cystic disease fluid protein 15 (GCDFP-15), which is regulated by the androgen receptor (AR), is a diagnostic marker for mammary differentiation in histopathology. We determined the expression of GCDFP-15 in breast cancer subtypes, its potential prognostic and predictive value, as well as its relationship to AR expression. METHODS: 602 pre-therapeutic breast cancer core biopsies from the phase III randomized neoadjuvant GeparTrio trial (NCT00544765) were investigated for GCDFP-15 expression by immunohistochemistry. Expression data were correlated with disease-free (DFS) and overall survival (OS) time as well as pathological complete response (pCR) to neoadjuvant chemotherapy. RESULTS: 239 tumors (39.7%) were GCDFP-15 positive. GCDFP-15 expression was positively linked to hormone receptor (HR) and HER2 positive tumor type, while most triple negative carcinomas were negative (p < 0.0001). GCDFP-15 was also strongly correlated to AR expression (p 0.001), and to the so-called molecular apocrine subtype (HR-/AR+, p < 0.0001). Higher rates of GCDFP-15 positivity were seen in tumors of lower grade (<0.0001) and negative nodal status (p = 0.008). GCDFP-15 positive tumors tended to have a more favourable prognosis than GCDFP-15 negative tumors (DFS (p = 0.052) and OS (p = 0.044)), which was not independent from other factors in multivariate analysis. GCDFP-15 expression was not linked to pCR. Histological apocrine differentiation was frequent in molecular apocrine carcinomas (60.7%), and was associated with GCDFP-15 within this group (p = 0.039). CONCLUSIONS: GCDFP-15 expression is higher in tumors with favorable prognostic features. GCDFP-15 expression is further a frequent feature of AR positive tumors and the molecular apocrine subtype. It might have reduced sensitivity as a diagnostic marker for mammary differentiation in triple negative tumors as compared to HR or HER2 positive tumor types.

PTK 7 is a transforming gene and prognostic marker for breast cancer and nodal metastasis involvement.

Protein Tyrosin Kinase 7 (PTK7) is upregulated in several human cancers; however, its clinical implication in breast cancer (BC) and lymph node (LN) is still unclear. In order to investigate the function of PTK7 in mediating BC cell motility and invasivity, PTK7 expression in BC cell lines was determined. PTK7 signaling in highly invasive breast cancer cells was inhibited by a dominant-negative PTK7 mutant, an antibody against the extracellular domain of PTK7, and siRNA knockdown of PTK7. This resulted in decreased motility and invasivity of BC cells. We further examined PTK7 expression in BC and LN tissue of 128 BC patients by RT-PCR and its correlation with BC related genes like HER2, HER3, PAI1, MMP1, K19, and CD44. Expression profiling in BC cell lines and primary tumors showed association of PTK7 with ER/PR/HER2-negative (TNBC-triple negative BC) cancer. Oncomine data analysis confirmed this observation and classified PTK7 in a cluster with genes associated with agressive behavior of primary BC. Furthermore PTK7 expression was significantly different with respect to tumor size (ANOVA, p = 0.033) in BC and nodal involvement (ANOVA, p = 0.007) in LN. PTK7 expression in metastatic LN was related to shorter DFS (Cox Regression, p = 0.041). Our observations confirmed the transforming potential of PTK7, as well as its involvement in motility and invasivity of BC cells. PTK7 is highly expressed in TNBC cell lines. It represents a novel prognostic marker for BC patients and has potential therapeutic significance.

PTK7 expression in triple-negative breast cancer.

BACKGROUND: Protein tyrosine kinase-7 (PTK7) plays an important role in cancer. Our aim was to evaluate PTK7 in triple-negative breast cancer (TNBC). MATERIALS AND METHODS: PTK7 Expression was assessed by immunohistochemistry (IHC) in 133 patients with TNBC. Expression levels were correlated with clinicopathological features and survival, taking chemotherapy into account. RESULTS: Positive PTK7 expression was detected in 28.6% of tumors. In the total population, no significant difference was detected in disease-free survival (DFS) or overall survival (OS) related to PTK7 status. However, in patients treated by chemotherapy, patients with PTK7-negative tumors seemed to have better DFS than those with PTK7-positive tumors, particularly for patients treated with only anthracycline-therapy drugs. In patients receiving other chemotherapy regimens, PTK7 status had no significant impact on DFS or OS. CONCLUSION: Our results support earlier findings that PTK7 may be associated with resistance to anthracycline-based chemotherapy.

Monocytes/macrophages support mammary tumor invasivity by co-secreting lineage-specific EGFR ligands and a STAT3 activator.

BACKGROUND: Tumor-associated macrophages (TAM) promote malignant progression, yet the repertoire of oncogenic factors secreted by TAM has not been clearly defined. We sought to analyze which EGFR- and STAT3-activating factors are secreted by monocytes/macrophages exposed to tumor cell-secreted factors. METHODS: Following exposure of primary human monocytes and macrophages to supernatants of a variety of tumor cell lines, we have analyzed transcript and secreted protein levels of EGFR family ligands and of STAT3 activators. To validate our findings, we have analyzed TAM infiltration levels, systemic and local protein levels as well as clinical data of primary breast cancer patients. RESULTS: Primary human monocytes and macrophages respond to tumor cell-derived factors by secreting EGFR- and STAT3-activating ligands, thus inducing two important oncogenic pathways in carcinoma cells. Tumor cell-secreted factors trigger two stereotype secretory profiles in peripheral blood monocytes and differentiated macrophages: monocytes secrete epiregulin (EREG) and oncostatin-M (OSM), while macrophages secrete heparin-binding EGF-like growth factor (HB-EGF) and OSM. HB-EGF and OSM cooperatively induce tumor cell chemotaxis. HB-EGF and OSM are co-expressed by TAM in breast carcinoma patients, and plasma levels of both ligands correlate strongly. Elevated HB-EGF levels accompany TAM infiltration, tumor growth and dissemination in patients with invasive disease. CONCLUSIONS: Our work identifies systemic markers for TAM involvement in cancer progression, with the potential to be developed into molecular targets in cancer therapy.

BRCA2 mutations and triple-negative breast cancer.

Recently, BRCA1 germline mutations were found in a high proportion (14-34%) of patients with triple-negative breast cancer (TNBC). BRCA2 was either not analyzed or showed much lower mutation frequencies. Therefore, we screened a group of TNBC patients (n = 30) of white European descent for mutations in BRCA2 as well as in BRCA1. Cases were unselected for age of disease-onset (median age at breast cancer diagnosis was 58 years, ranging from 37 to 74 years), family history of cancer and BRCA1 and BRCA2 mutation status. Half of the patients (15/30) showed a family history of breast and/or ovarian cancer. A high frequency of deleterious germline mutations was observed in BRCA2 (5/30; 16.7%), and only one case showed a BRCA1 mutation (3.3%). Although the study group was small, these results point to BRCA2 mutations being important in TNBC.

Effect of neoadjuvant anthracycline-taxane-based chemotherapy in different biological breast cancer phenotypes: overall results from the GeparTrio study.

In order to explore the effect of neoadjuvant chemotherapy (NACT) on clinical mid-course and pathological complete response (pCR) at surgery in different biological breast cancer subtypes. The GeparTrio study included 2,072 patients with operable or locally advanced breast cancer. After two cycles with docetaxel, doxorubicin and cyclophosphamide (TAC) patients were randomized according to their clinical response. Clinical and biological factors were assessed for predicting clinically mid-course response and pCR at surgery. The overall pCR rate, defined as no invasive residuals in breast and axilla, was 20.5%. The highest pCR rate of 57% was observed in patients below 40 years of age with triple negative or grade 3 tumors. Independent factors for mid-course response and pCR were: young age, non-T4 tumors, high grade, and hormone receptor status, the strongest single predictive factor. Within the biological subtypes, grading was an independent factor to predict pCR for luminal tumors, clinical tumor stage for the HER2 like tumors and age for the triple negative ones. Grading gave independent information for mid-course response within the triple negative group. No factor predicted mid-course response within the other groups. Grading and age can identify subgroups within the luminal and triple negative patients who have an increased benefit from NACT.