doi:10.3390/cancers15020329engGascón-Ruiz, MartaRamírez-Labrada, ArielLastra, RodrigoMartínez-Lostao, LuisPaño-Pardo, J. RamónSesma, AndreaZapata-García, MaríaMoratiel, AlbaQuílez, ElisaTorres-Ramón, IreneYubero, AlfonsoDomingo, María PilarEsteban, PatriciaGálvez, Eva M.Pardo, JuliánIsla, DoloresA Subset of PD-1-Expressing CD56bright NK Cells Identifies Patients with Good Response to Immune Checkpoint Inhibitors in Lung CancerART-2023-132236(1) Despite the effectiveness of immune checkpoint inhibitors (ICIs) in lung cancer, there is a lack of knowledge about predictive biomarkers. The objective of our study is to analyze different subsets of T-lymphocytes and natural killer (NK) cells as predictive biomarkers in a cohort of patients with nonsmall cell lung cancer (NSCLC) treated with ICI. (2) This is an observational, prospective study with 55 NSCLC patients treated with ICI. A total of 43 T and NK cell subsets are analyzed in peripheral blood, including the main markers of exhaustion, differentiation, memory, activation, and inhibition. (3) Regarding the descriptive data, Granzyme B+CD4+ Treg lymphocytes stand out (median 17.4%), and within the NK populations, most patients presented cytotoxic NK cells (CD56+CD3−CD16+GranzymeB+; median 94.8%), and about half of them have highly differentiated adaptive-like NK cells (CD56+CD3−CD16+CD57+ (mean 59.8%). A statistically significant difference was observed between the expression of PD1 within the CD56bright NK cell subpopulation (CD56+CD3−CD16−PD-1+) (p = 0.047) and a better OS. (4) Circulating immune cell subpopulations are promising prognostic biomarkers for ICI. Pending on validation with a larger sample, here we provide an analysis of the major circulating T and NK cell subsets involved in cancer immunity, with promising results despite a small sample size.2023http://zaguan.unizar.es/record/12186010.3390/cancers15020329http://zaguan.unizar.es/record/121860oai:zaguan.unizar.es:121860info:eu-repo/grantAgreement/ES/AEI/PID2020-113963RB-I00info:eu-repo/grantAgreement/ES/AEI/PTA2019-016739-Iinfo:eu-repo/grantAgreement/ES/DGA/B29-20Rinfo:eu-repo/grantAgreement/ES/ISCIII/CB21-13-00087Cancers 15, 2 (2023), 329 [19 pp.]byhttps://creativecommons.org/licenses/by/4.0/deed.esinfo:eu-repo/semantics/openAccess