PD-L1 in Systemic Immunity: Unraveling Its Contribution to PD-1/PD-L1 Blockade Immunotherapy

• Main Authors: Ana Bocanegra, Ester Blanco, Gonzalo Fernandez-Hinojal, Hugo Arasanz, Luisa Chocarro, Miren Zuazo, Pilar Morente, Ruth Vera, David Escors, Grazyna Kochan
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: International Journal of Molecular Sciences
• Subjects: PD-L1; immunotherapy; immune; checkpoint inhibition; systemic myeloid subsets; liquid biopsy
• Online Access: https://www.mdpi.com/1422-0067/21/16/5918
• ISSN: 1661-6596; 1422-0067

The use of monoclonal antibodies targeting PD-1/PD-L1 axis completely changed anticancer treatment strategies. However, despite the significant improvement in overall survival and progression-free survival of patients undergoing these immunotherapy treatments, the only clinically accepted biomarker with some prediction capabilities for the outcome of the treatment is PD-L1 expression in tumor biopsies. Nevertheless, even when having PD-L1-positive tumors, numerous patients do not respond to these treatments. Considering the high cost of these therapies and the risk of immune-related adverse events during therapy, it is necessary to identify additional biomarkers that would facilitate stratifying patients in potential responders and non-responders before the start of immunotherapies. Here, we review the utility of PD-L1 expression not only in tumor cells but in immune system cells and their influence on the antitumor activity of immune cell subsets.