Prognostic Value of the Lung Immune Prognostic Index in Advanced Non-Small Cell Lung Cancer Treated with Nivolumab: A Real-World Analysis Beyond PD-L1 Expression

Background: The Lung Immune Prognostic Index (LIPI), based on the derived neutrophil-to-lymphocyte ratio and lactate dehydrogenase, may reflect systemic inflammation and tumor-related metabolic burden. This study evaluated the prognostic value of pretreatment LIPI and its relationship with programmed death-ligand 1 (PD-L1) expression in patients with advanced non-small cell lung cancer (NSCLC) receiving nivolumab after first-line therapy. Methods: A total of 158 patients were included in this retrospective, single-center study. Patients were classified into LIPI 0, LIPI 1, or LIPI 2 groups according to their pretreatment LIPI scores. Progression-free survival (PFS) and overall survival (OS) were assessed using Kaplan–Meier analysis and multivariable Cox regression. The prognostic value of LIPI was also evaluated within PD-L1-negative and PD-L1-positive subgroups, and LIPI × PD-L1 interactions were explored. Harrell’s concordance index was used to examine whether adding LIPI improved model discrimination beyond clinical variables and PD-L1 expression. PD-L1 data were available for 145 patients. Results: Median PFS was 566, 340, and 109 days for the LIPI 0, LIPI 1, and LIPI 2 groups, respectively, while median OS was 841, 760, and 201 days, respectively; the differences were statistically significant for both outcomes (both p < 0.001). The objective response rate (ORR) was 55.6%, 36.5%, and 4.9%, whereas the disease control rate (DCR) was 75.9%, 65.1%, and 14.6% in the LIPI 0, LIPI 1, and LIPI 2 groups, respectively (both p < 0.001). In multivariable analyses, higher LIPI remained independently associated with shorter PFS and OS, with the strongest association observed in the LIPI 2 group. LIPI also differentiated survival outcomes within both PD-L1-negative and PD-L1-positive subgroups, although no significant LIPI × PD-L1 interaction was identified for PFS or OS. The addition of LIPI increased the C-index from 0.583 to 0.698 for PFS (ΔC-index, 0.115; p < 0.001) and from 0.588 to 0.697 for OS (ΔC-index, 0.109; p = 0.003). Conclusions: Pretreatment LIPI was independently associated with PFS and OS in patients with advanced NSCLC receiving nivolumab after first-line therapy. Its association remained after adjustment for available PD-L1 expression data, and its addition improved model discrimination. These findings suggest that LIPI may provide prognostic information complementary to PD-L1 expression and routinely available clinical factors.