Circulating natural killer cells as prognostic value for non-small-cell lung cancer patients treated with Immune checkpoint inhibitors: correlation with sarcopenia

Background: Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of tumors. Natural killer (NK) cells can play an important role in cancer immune surveillance. The aim of this prospective observational study was to analyze peripheral blood mononuclear cells (PBMCs) in patients with advanced non-small-cell lung cancer (NSCLC) receiving ICIs in order to identify predictive factors for better survival outcomes. Methods: Forty-seven stage IV NSCLC patients were enrolled. Patients underwent baseline (T0) and longitudinal (T1) evaluations after ICIs. Peripheral immune blood cell counts were analyzed using flow cytometry. Results: Basal levels of CD3−CD56+ NK cells were higher in patients with controlled disease (DC) compared to progression disease (PD) patients (127 cells/µL vs. 27.8 cells/µL, p < 0.001). Lower NK cell values were independent prognostic factors for shorter overall survival (OS) (HR 0.992; 95% CI 0.987–0.997, p < 0.001) and progression-free survival (PFS) (HR 0.988; 95% CI 0.981–0.994, p < 0.001). During the longitudinal evaluation, CD3−CD56+ NK cells (138.1 cells/µL vs. 127 cells/µL, p = 0.025) and CD56bright NK cells (27.4 cells/µL vs. 18.1 cells/µL, p = 0.034) significantly increased in the DC group. Finally, lower values of CD3−CD56+ NK cells (28.3 cells/µL vs. 114.6 cells/µL, p = 0.004) and CD56dim NK cells (13.2 cells/µL vs. 89.4 cells/µL, p < 0.001) were found in sarcopenic patients compared to patients without sarcopenia. Conclusions: Peripheral NK cells could represent a non-invasive and useful tool to predict ICI therapy response in NSCLC patients, and the association of low NK cell levels with sarcopenia deserves even more attention in clinical evaluation.