Repression of miR-146a in predicting poor treatment outcome in triple-negative breast cancer

In the era of precision medicine, the highly aggressive and heterogenous triple-negative breast cancer (TNBC) is still characterized by limited options to support personalized prognosis and guide therapeutic interventions. Thereafter, the aim of the present study has been the thorough evaluation of miR-146a as a novel molecular indicator of TNBC prognosis and treatment outcome, utilizing four independent TNBC cohorts.

miR-146a levels were clinically evaluated in our screening (n = 122) and three external validation TNBC cohorts (de Rinaldis et al. 2013, n = 114; Jézéquel et al. 2015, n = 107; TCGA, n = 180). Analysis of miR-146a and validated gene targets was performed in Jézéquel et al. and TCGA validation cohorts. Patients' survival, recurrence and metastasis were determined as clinical endpoints for the survival analysis. Internal validation was performed by bootstrap analysis and clinical net benefit was evaluated by decision curve analysis.

Reduction of miR-146a is strongly associated with patients' poor survival and can predict post-treatment disease early-recurrence, independently of tumor size, lymph node status, histological grade and patients' age. The analysis of the external validation cohorts corroborated the unfavorable nature of miR-146a repression regarding patients' survival and, strikingly, unveiled the ability of miR-146a to predict TNBC metastasis. Combined assessment of miR-146a levels and lymph node status resulted in superior risk-stratification of TNBC patients and higher clinical benefit regarding disease prognosis and post-treatment outcome. Ultimately, miR-146a was negatively associated with EGFR and SOX2 expression in TNBC.

miR-146a evaluation could ameliorate personalized prognosis and support precision medicine decisions in TNBC.