Programmed Death-Ligand 1 (PD-L1) as Immunotherapy Biomarker in Breast Cancer

• Published in: Cancers Vol. 14; no. 2; p. 307
• Main Authors: Núñez Abad, Martín, Calabuig-Fariñas, Silvia, Lobo de Mena, Miriam, Torres-Martínez, Susana, García González, Clara, García García, José Ángel, Iranzo González-Cruz, Vega, Camps Herrero, Carlos
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 08.01.2022; MDPI
• Subjects: Algorithms; Antibodies; Antigens; Apoptosis; biomarker; Biomarkers; Breast cancer; Cell activation; Chemotherapy; Clinical trials; Cloning; Death; Divergence; Granulocytes; Immune checkpoint; Immune checkpoint inhibitors; Immune system; Immunotherapy; Kinases; Ligands; Lung cancer; Lymphocytes; Lymphocytes T; Metastases; Patients; PD-1 protein; PD-L1; PD-L1 protein; Physiology; prognostic value; Review; Tumor microenvironment; Tumors; PD-L1; breast cancer; prognostic value; biomarker; chemotherapy; immunotherapy
• ISSN: 2072-6694; 2072-6694
• DOI: 10.3390/cancers14020307

Breast cancer constitutes the most common malignant neoplasm in women around the world. Approximately 12% of patients are diagnosed with metastatic stage, and between 5 and 30% of early or locally advanced BC patients will relapse, making it an incurable disease. PD-L1 ligation is an immune inhibitory molecule of the activation of T cells, playing a relevant role in numerous types of malignant tumors, including BC. The objective of the present review is to analyze the role of PD-L1 as a biomarker in the different BC subtypes, adding clinical trials with immune checkpoint inhibitors and their applicable results. Diverse trials using immunotherapy with anti-PD-1/PD-L1 in BC, as well as prospective or retrospective cohort studies about PD-L1 in BC, were included. Despite divergent results in the reviewed studies, PD-L1 seems to be correlated with worse prognosis in the hormone receptor positive subtype. Immune checkpoints inhibitors targeting the PD-1/PD-L1 axis have achieved great response rates in TNBC patients, especially in combination with chemotherapy, making immunotherapy a new treatment option in this scenario. However, the utility of PD-L1 as a predictive biomarker in the rest of BC subtypes remains unclear. In addition, predictive differences have been found in response to immunotherapy depending on the stage of the tumor disease. Therefore, a better understanding of tumor microenvironment, as well as identifying new potential biomarkers or combined index scores, is necessary in order to make a better selection of the subgroups of BC patients who will derive benefit from immune checkpoint inhibitors.