Efficacy of biological agents in metastatic triple-negative breast cancer

Metastatic triple-negative breast cancer (mTNBC) represents 15% of invasive breast cancers. Prognosis is poor, and there is no specific target therapy but biological agents combined with chemotherapy may be effective. To assess the role of biological agents in metastatic triple-negative breast cancer we performed a systematic review of phase III randomized controlled trials published from January 2006 to February 2013 and presentations at ESMO, ASCO, and SABCS congresses in 2010-2012. We consulted PubMed and ClinicalTrials.gov. Only studies comparing biological agents and chemotherapy versus chemotherapy alone were considered. Relevant statistical variables were log of the hazard ratio and relative variance for progression-free survival (PFS) and overall survival (OS). Of 353 PubMed publications and 229 studies registered on ClinicalTrials.gov, 10 trials were selected and 5293 patients were analyzed: 1546 had mTNBC. Biological agents considered were bevacizumab, sunitinib, sorafenib, lapatinib, iniparib and cetuximab. In addition, a meta analysis of the four studies containing bevacizumab was performed and it showed a PFS improvement with a relative risk reduction of 35% (95% CI: 25-43%). No effect on OS was observed. No PFS and OS benefit was detected with the other agents. No improvement of OS was detected in patients treated with biological agents plus chemotherapy, while a significant PFS improvement was observed only for bevacizumab and cetuximab. The overall impact of these agents on patient survival was not as great as expected, probably because the molecular basis of this illness needs to be better understood so that treatment can be more appropriately tailored.