Triple negative phenotype and N-ratio are important for prognosis in patients with stage IIIB non-inflammatory breast carcinoma

Novel model for basaloid triple-negative breast cancer: behavior in vivo and response to therapy

INTRODUCTION

The basaloid triple-negative breast cancer (B-TNBC) is one of the most aggressive, therapy-resistant, and metastatic tumors. Current models do not recapitulate the basaloid phenotype of TNBC, thus limiting the understanding of its biology and designing new treatments. We identified HCC1806 as a line expressing typical B-TNBC markers, engineered a subline with traceable reporters, and determined growth, drug sensitivity, recurrence, and vascular and metastatic patterns of orthotopic xenografts in immunodeficient mice.

METHODS

mRNA and protein analyses showed that HCC1806 expresses basal but not luminal or mesenchymal markers. HCC1806-RR subline stably expressing red fluorescent protein and Renilla luciferase was generated and characterized for sensitivity to chemodrugs, orthotopic growth, vascular properties, recurrence, metastasis, and responsiveness in vivo.

RESULTS

The HCC1806 cells were highly sensitive to paclitaxel, but cytotoxicity was accompanied by pro-survival vascular endothelial growth factor-A loop. In vivo, HCC1806-RR tumors display linear growth, induce peritumoral lymphatics, and spontaneously metastasize to lymph nodes (LNs) and lungs. Similarly to human B-TNBC, HCC1806-RR tumors were initially sensitive to taxane therapy but subsequently recur. Bevacizumab significantly suppressed recurrence by 50% and reduced the incidence of LN and pulmonary metastases by, respectively, 50% and 87%.

CONCLUSIONS

The HCC1806-RR is a new model that expresses bona fide markers of B-TNBC and traceable markers for quantifying metastases. Combination of bevacizumab with nab-paclitaxel significantly improved the outcome, suggesting that this approach can apply to human patients with B-TNBC. This model can be used for defining the metastatic mechanisms of B-TNBC and testing new therapies.

Significance of histomorphology of early triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous disease. Possibly genetic characterisation provides the most appropriate information on tumour biology and prognosis, but it is only limitedly available in clinical practice. The aim of this investigation was to explore what additional prognostic information could be gained from detailed histomorphologic report.

PATIENTS AND METHOD

patients were selected retrospectively operated from 2005 to 2009 in one institution and charts were revised. Beyond age, tumour and nodal status, histologic grade and therapy, the additional pathologic characteristics were also involved in analysis: necrosis, lymphocytic infiltration, peritumoural vascular invasion (PVI), perineural invasion, DCIS extent and grade, perinodal spread, mitotic activity index (MAI).

RESULTS

295 early TNBC were involved. In univariate survival analysis with a mean follow-up of 3.57 years the tumour size, the nodal status, type of operation (conservation or mastectomy), irradiation, PVI and perinodal spread proved to be significantly connected with both disease free survival (DFS) and breast cancer specific overall survival (BSOS), and necrosis and chemotherapy with BSOS. Necrosis analysed together with lymphocytic infiltrate showed greater predicting power. In multivariate analysis nodal metastasis, necrosis positive/lymphacytic infiltration negative status and lack of irradiation has significant negative impact on DFS (p = <0.0001 HR:1.98 [1.4-2.77], p = <0.017 HR:2.1 [1.1-3.8], p = <0.001 HR:0.25 [0.11-0.57], respectively) and BSOS (p = <0.0001 HR:2.47 [1.8-3.4], p = <0.017 HR:3.7 [1.6-8.2], p = <0.0017 HR:0.24 [0.1-0.58], respectively). For DFS perivascular invasion also showed significant effect (p = <0.042 HR:2.5 [1.0-6.0]). Nodal status was the strongest prognostic parameter but other histomorphologic parameters can be used for prognosis prediction.