Prognostic value of plasma D-dimer levels in advanced non-small cell lung cancer patients treated with immune checkpoint inhibitors: a retrospective study

BACKGROUND: Plasma D-dimer is of great significance for the clinical exclusion of tumor-related thrombosis. Previous studies have shown its predictive role in non-small cell lung cancer (NSCLC) treated with chemotherapy. However, whether pretreatment D-dimer could predict the efficacy and prognosis in NSCLC patients treated with immune checkpoint inhibitors (ICIs) remains unclear. METHODS: Advanced NSCLC patients treated with ICIs at the Chinese PLA General Hospital between January 2015 and March 2019 were enrolled. Patients were divided into a pretreatment normal D-dimer group (≤0.5 µg/mL) and high D-dimer group (>0.5 µg/mL). Optimization-based approach was applied to balance baseline covariates between the 2 groups, including age, sex, histological type, smoking history, stage, Eastern Cooperative Oncology Group Performance Status (ECOG PS), lines of treatment, ICI drugs, brain metastasis, treatment type, and D-dimer levels. Kaplan-Meier analysis and Cox proportional hazards model were used for analyzing survival data, including progression-free survival (PFS, the time from initial ICI treatment to PD or death), overall survival (OS, the time between initial ICI treatment and death), and hazard ratio (HR). Follow-up of all patients was performed by searching electronic medical records and counseling telephone. The follow-up cut-off date was July 6, 2020. RESULTS: This study included 277 advanced NSCLC patients. Among the enrolled patients, 23.1% were female, 64.6% had non-squamous cell lung cancer, and 79.4% were stage IV. Univariate and multivariate analysis showed that pretreatment high D-dimer levels were independently associated with shortened PFS and OS (P<0.01). Subgroup analysis confirmed that pretreatment high D-dimer levels were associated with poor prognosis in most subsets. After balancing baseline covariates between the high D-dimer group and normal D-dimer group, the results indicated that patients with pretreatment high D-dimer levels had significantly shorter PFS [median: 6.4 vs. 11.5 months; HR, 1.70; 95% confidence ratio (CI): 1.25–2.37; P<0.001] and OS (median: 12.7 vs. 30.4 months; HR, 2.29; 95% CI: 1.54–3.41; P<0.001) than those with pretreatment normal D-dimer levels. CONCLUSIONS: Pretreatment plasma D-dimer could serve as a convenient prognostic biomarker for advanced NSCLC patients receiving ICI treatment. Patients with pretreatment high D-dimer levels may have poor PFS and OS.