Simple Summary Breast cancer (BC) is the most frequent malignancy diagnosed in 2020 worldwide. Despite significant advances in BC therapy, its pathogenesis is still not fully understood, and effective therapy is one of the most important challenges in current oncology. The article presents the state of the knowledge on vorinostat (SAHA) in the therapy of various histological subtypes of BC, individually or in polytherapy with other active compounds, in in vitro, in vivo and clinical trials settings.

Vorinostat (SAHA), an inhibitor of class I and II of histone deacetylases, is the first histone deacetylase inhibitor (HDI) approved for the treatment of cutaneous T-cell lymphoma in 2006. HDIs are promising anticancer agents that inhibit the proliferation of many types of cancer cells including breast carcinoma (BC). BC is a heterogeneous disease with variable biological behavior, morphological features, and response to therapy. Although significant progress in the treatment of BC has been made, high toxicity to normal cells, serious side effects, and the occurrence of multi-drug resistance limit the effective therapy of BC patients. Therefore, new active agents which improve the effectiveness of currently used regimens are highly needed. This manuscript analyzes preclinical and clinical trials data of SAHA, applied individually or in combination with other anticancer agents, considering different histological subtypes of BC.