Immune checkpoints: A therapeutic target in triple negative breast cancer

Abstract

Early clinical trials investigating monoclonal antibodies targeting the T-cell inhibitory receptor programmed cell death 1 (PD-1) and its ligand PD-L1 have shown efficacy in melanoma, non-small cell lung cancer and renal cell carcinoma. We recently demonstrated PD-L1 expression in 20% of triple negative breast cancers suggesting that targeting the PD-1/PD-L1 immune checkpoint may be an effective treatment modality in patients with this disease.

Keywords: PD-L1; PI3K; biomarker; immunotherapy; triple negative breast cancer.

Figure 1. Combination immunotherapy. For patients with metastatic breast cancer, monotherapy consisting of vaccination or administration of monoclonal antibodies targeting immune checkpoints such as programmed cell death 1 (PD-1) or its ligand (PD-L1) may be insufficient to eradicate disease. A combination strategy wherein an antigen-specific cytotoxic T lymphocyte (CTL) response is stimulated by vaccination and an anti-PD-1 or anti-PD-L1 antibody is used to overcome inhibitory pathways, may enhance the antitumor immune response thereby resulting in increased tumor cell death and improved patient outcomes.