Statistical analysis
BRAIN METASTASIS, LIVER METASTASIS
All statistical analyses were conducted using SPSS version 23.0 and RStudio 1.2.5001. Continuous variables were expressed as median and range, and classification variables were expressed as frequency and percentage. Kaplan-Meier method was used to evaluate PFS and DoR, and Cox proportional hazards model was used to estimate hazard ratio (HR) and 95% confidence interval (CI). PFS was analyzed in different subgroups according to age (≤65 years, >65 years), sex (male, female), metastatic sites (with or without brain metastasis, with or without liver metastasis), modified neutrophil to lymphocyte ratio (dNLR, ≤3, >3), serum sodium (<135, ≥135), serum lactate dehydrogenase (LDH, ≤260, >260), the absolute value of CD4+ cells (≤600/μl, >600/μl), the absolute value of CD8+ cells (≤450/μl, >450/μl), CD4+/CD8+ (1-2, <1 or >2) and the occurrence of irAEs (with or without irAEs).The HR and 95%CI of subgroups were calculated using the non-stratified Cox risk ratio model, and the association between different subgroups and median PFS was calculated. 