Post-treatment neutrophil-to-lymphocyte ratio (NLR) predicts response to anti-PD-1/PD-L1 antibody in SCLC patients at early phase.

Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation index (SII) have been identified as predictors of treatment response in a variety of cancers. We conducted a retrospective analysis to investigate the usefulness of NLR, PLR and SII at baseline and at 6 weeks post-treatment as predictors of response to anti-PD-1/PD-L1 antibody treatment in small cell lung cancer (SCLC). Data of 41 SCLC patients receiving immunotherapy as second- or later-line treatment were analyzed. The overall median progression-free survival (PFS) was 5.1 months (95% CI 3.2-6.2). The median PFS was significantly longer in patients with NLR < 5 than in patients with NLR ≥ 5 at 6 weeks post treatment (HR = 0.29, 95%CI 0.09-0.96, P = 0.04). However, median PFS was comparable between patients with NLR < 5 and patients with NLR ≥ 5 at baseline (HR = 0.75, 95% CI 0.24-2.26, P = 0.56). The median PFS was similar between patients with PLR < 169 and those with PLR ≥ 169 at baseline (HR = 0.67, 95% CI 0.25-1.80, P = 0.43) and at 6 weeks post treatment (HR = 0.69, 95% CI 0.25-1.86, P = 0.46). No statistically different PFS was found between patients with SII < 730 and those with SII ≥ 730 at baseline (HR = 0.70, 95% CI 0.26-1.89, P = 0.48) and at 6 weeks post treatment (HR = 0.38, 95% CI 0.013-1.09, P = 0.07). In conclusion, NLR at 6 weeks after start of treatment appears to be a biomarker of response in the early phase in SCLC patients treated with anti-PD-1/PD-L1 antibodies as second- or later-line treatment.