Gastric Inflammatory Prognostic Index (GIPI) in Patients with Metastatic Gastro-Esophageal Junction/Gastric Cancer Treated with PD-1/PD-L1 Immune Checkpoint Inhibitors

Background Immune checkpoint inhibitors (ICIs) demonstrated improved overall survival (OS) in heavily pretreated unselected patients with metastatic gastro-esophageal junction (mGOJ)/gastric cancer (GC). Attempts to select patients based on programmed death-ligand 1 (PD-L1) expression appear to be suboptimal. A strong rationale suggests a prognostic role for inflammatory biomarkers for ICI-treated patients with mGOJ/GC. Objective Our objective was to assess whether inflammatory markers are associated with survival in ICI-treated patients with mGOJ/GC. Methods Ten inflammatory markers were retrospectively analyzed at baseline in 57 patients with mGOJ/GC with unknown PD-L1 status treated with second-line ICIs and correlated with OS. Selected variables were then analyzed in a multivariate Cox-regression model and used to build a GIPI nomogram. Results Neutrophil/lymphocyte ratio (NLR) and C-reactive protein (CRP) as continuous variables and albumin categorized as less than versus greater than 30 g/dL were the most significant predictors of OS and were used to build the GIPI nomogram. Nomogram-based lowest, mid-low, mid-high, and highest risk quartiles were associated with median OS (mOS) of 14.9, 7.1, 5.6, and 2.1 months, respectively (hazard ratio [HR] of highest vs. lowest risk 4.94; p = 0.0002). By optimally dichotomizing CRP and NLR, patients with one or more of the risk factors NLR > 6, CRP > 15 mg/L, and albumin < 30 g/dL (n = 29) had an mOS of 3.9 versus 14.2 months for patients with no risk factor (n = 28) (HR 2.48; p = 0.0015). Conclusions GIPI, combining NLR, CRP, and albumin, is the first inflammatory index with a significant prognostic value in patients with mOGJ/GC receiving ICIs. GIPI merits validation in independent cohorts and prospective clinical trials.