Predictive response markers for immune response blocks

Despite the unprecedented success in using immune checkpoint inhibitors in the treatment of lung cancer, melanoma, hypermutable tumors of various localization, etc., a significant proportion of patients receiving these drugs do not respond to treatment. Predictive markers routinely used in the selection of patients for immunotherapy, in particular, the level of expression of PD-L1 and the presence of microsatellite instability, have certain limitations. Over the past decade, many other biomarkers designed to predict response to immunotherapy have been proposed, namely: tymor mutation burden, composition of lymphocytic infiltrate; allelic composition of the major histocompatibility complex; relationship between the numbers of different formed elements of blood as well as between its biochemical parameters; microflora of the digestive tract, etc. These markers can directly or indirectly reflect the immunogenicity of the tumor itself, as well as the state of systemic and intratumoral immune response. The predictive power and reliability of these markers are extremely different. When preparing this review, we conducted a literature search for recent studies regarding predictors of efficacy for immune checkpoint inhibitors published in the journals included in the databases, such as Pubmed, Web of Science, and Scopus.