Immunophenotyping of peripheral blood in NSCLC patients discriminates responders to immune checkpoint inhibitors

Purpose Immune checkpoint inhibitors (ICIs) dramatically changed the prognosis of patients with NSCLC. Unfortunately, a reliable predictive biomarker is still missing. Commonly used biomarkers, such as PD-L1, MSI, or TMB, are not quite accurate in predicting ICI efficacy. Methods In this prospective observational cohort study, we investigated the predictive role of erythrocytes, thrombocytes, innate and adaptive immune cells, complement proteins (C3, C4), and cytokines from peripheral blood of 224 patients with stage III/IV NSCLC treated with ICI alone (pembrolizumab, nivolumab, and atezolizumab) or in combination (nivolumab + ipilimumab) with chemotherapy. These values were analyzed for associations with the response to the treatment and survival endpoints. Results Higher baseline Tregs, MPV, hemoglobin, and lower monocyte levels were associated with favorable PFS and OS. Moreover, increased baseline basophils and lower levels of C3 predicted significantly improved PFS. The levels of the baseline immature granulocytes, C3, and monocytes were significantly associated with the occurrence of partial regression at the first restaging. Multiple studied parameters ( n = 9) were related to PFS benefit at the time of first restaging as compared to baseline values. In addition, PFS nonbenefit group showed a decrease in lymphocyte count after three months of therapy. The OS benefit was associated with higher levels of lymphocytes, erythrocytes, hemoglobin, MCV, and MPV, and a lower value of NLR after three months of treatment. Conclusion Our work suggests that parameters from peripheral venous blood may be potential biomarkers in NSCLC patients on ICI. The baseline values of Tregs, C3, monocytes, and MPV are especially recommended for further investigation.