The Anticancer Power of the Immune System – New Perspectives for Patients with Triple-Negative Breast Cancer

Abstract

Triple-Negative Breast Cancer (TNBC) represents a heterogeneous disease that includes different subtypes and accounts for approximately 20% of all breast cancers (BC). TNBC is oestrogen receptor-negative, progesterone receptor-negative, and human epidermal growth factor receptor 2-negative. In addition, the androgen receptor is expressed in roughly 10–32% of TNBC cases. TNBC is characterised by worse outcomes, including higher risks of relapse and visceral crisis compared to other BC subtypes (especially during the first 2 years post BC diagnosis). Programmed death-ligand 1 (PD-L1) is widely expressed on the surface of lymphocytes, monocytes, natural killer cells, macrophages, and some other cells. Moreover, PD-L1 expression has been explored in different types of cancer (e.g., malignant melanoma, non-small cell lung cancer, renal cell carcinoma, and colon cancer). Due to limited treatment options for TNBC, there is an urgent need for the development of novel diagnostic and therapeutic strategies. To fulfil this unmet need, different approaches, including immunotherapy, have been investigated in clinical studies (with the goal of matching therapies with specific BC subtypes). This article discusses some diagnostic considerations relevant to patients with TNBC (focussing on advanced or metastatic disease). It