Objective   To determine the value of the systemic immune inflammation index (SII) and other inflammatory factors in predicting the efficacy and prognosis of anti-PD-1 antibody treatment in non-small cell lung cancer (NSCLC) patients.

  Methods   We retrospectively analyzed the hematological and clinical data of 64 stage ⅢB-Ⅳ NSCLC patients treated with anti-PD-1 antibodies. One-way analysis of variance was used to evaluate all inflammatory indexes at different time points: before treatment, when the best curative effect was achieved, and when the disease progressed. Meanwhile, the optimal critical values of inflammatory indexes were determined using receiver operating characteristic curve (ROC) analysis. The correlations between these indexes and patient survival were analyzed using the chi-square test and Kaplan–Meier estimation.

  Results   The inflammatory indexes were significantly lower when the best curative effect was achieved than at the baseline; however, these values increased again when the disease progressed. The optimal critical values for SII, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) were 822.39, 4.20, 0.58, and 269.85, respectively. Moreover, the best cut-off values of serum levels of inflammation-related factors such as γ-glutamyl transferase (γ-GGT), lactate dehydrogenase (LDH), fibrinogen (Fbg), and D-dimer were 55.00 U/L, 255.00 U/L, 3.94 g/L and 1,513.19 ng/mL, espectively; higher PLR, SII, LDH, Fbg, and D-dimer values predicted poorer progression-free survival (PFS) in NSCLC patients (P<0.05). Multivariate analysis showed that the baseline LDH level was an independent risk factor for PFS (P=0.016).

  Conclusions   In patients with advanced NSCLC, high baseline levels of inflammatory markers indicate relatively poor efficacy of anti-PD-1 antibodies. Thus, dynamic monitoring of inflammatory markers can predict the efficacy of anti-PD-1 antibody treatment and has a certain role in the prognostication of patients.