The circulating pool of functionally competent NK and CD8+ cells predicts the outcome of anti-PD1 treatment in advanced NSCLC. (January 2019) - Mazzaschi, Giulia
Highlights: Immune checkpoint blockade (ICB) has shown unprecedented results in NSCLC. Immune profiles predictive of ICB efficacy have not been entirely assessed. Tissue and circulating immune cells were analyzed in nivolumab treated NSCLC. The pool size of circulating NK and CD8+ cells positively impacts on ICB response. Cytometric assay of immune effector cells may define patients who benefit from ICB. Abstract: Introduction: A prospective investigation of the circulating immune profile in NSCLC patients receiving nivolumab was performed to identify potentially predictive parameters. Methods: Flow Cytometry of peripheral blood (PB) CD3+, CD8+, CD4+, NK, Treg and MDSCs was prospectively performed in 31 consecutive advanced NSCLC patients at baseline (T0) and after 2 (T1) and 4 (T2) cycles of bi-weekly nivolumab. Functional molecules (PD-1, CD3ζ, Granzyme B, Perforin), cell proliferation (Ki67) and NK receptors (NKG2 A, NKG2D, NKp30) were also explored. The immunohistochemical evaluation of PD-L1 and TILs was restricted to available tumor biopsies. Tissue and circulating parameters were correlated to clinico-pathological features and treatment outcomes. Results: KRAS mutations, active smoking, COPD and steroid treatment conditioned a different distribution of circulating phenotypes. At baseline, clinical benefit (CB, n = 19) group displayed higher number of phenotypically active NK and PD-1+CD8+ cells (p < 0.01) compared to non-responders (NR, n = 12). Prolonged survival outcomes (p < 0.01) were recorded in cases with high baseline circulating NK and PD-1+CD8+ cells. At tissue level, low PD-1 expression in CD8 + TILs was a positive prognostic feature (p < 0.001). Strikingly, high circulating NK and PD-1+CD8+ cells combined with low PD-1/CD8+ ratio in TILs characterized a privileged context able to provide a significantly prolonged (p < 0.01) progression-free survival (PFS). During PD-1 blockade, NKs progressively raised in CB while declined in NR (p < 0.05) and this phenomenon was counterbalanced by parallel changes in Treg. Conclusion: The functional pool of circulating NKs associated with a divergent PD-1 expression in blood and tissue CD8+ lymphocytes portrays an immune profile predictive of anti-PD1 treatment efficacy.