Baseline Gustave Roussy Immune Score and Survival in Extensive-Stage Small-Cell Lung Cancer Treated with First-Line Chemoimmunotherapy.

BACKGROUND

First-line chemoimmunotherapy has improved outcomes in extensive-stage small-cell lung cancer (ES-SCLC), but survival remains heterogeneous and routine-care prognostic tools are limited.

PATIENTS AND

METHODS

We retrospectively analyzed consecutive adults with stage IV ES-SCLC treated with platinum-etoposide plus a programmed death-ligand 1 inhibitor at three Spanish hospitals from August 2021 to December 2024. Outcomes included overall survival (OS), progression-free survival (PFS), objective response, and immune-related toxicity. Baseline Gustave Roussy Immune Score (GRIm) was defined as high-risk when at least two of albumin <35 g/L, lactate dehydrogenase above the upper limit of normal, and neutrophil-to-lymphocyte ratio >6 were present. Baseline Cox models included high-risk GRIm, platelet-to-lymphocyte ratio >180, and Eastern Cooperative Oncology Group performance status ≥2; maintenance exposure was assessed in a 3-month OS landmark analysis. Analyses were exploratory.

RESULTS

Among 51 patients, mean age was 64.2 years, 72.5% were men, and 82.3% had ECOG performance status 0-1. During follow-up, 43 deaths and 50 PFS events occurred. Objective response rate was 70.6%, median OS was 11.9 months, and median PFS was 5.7 months. Median OS was 14.2 months with low-risk GRIm and 5.4 months with high-risk GRIm. High-risk GRIm was independently associated with worse OS (hazard ratio [HR] 5.59) and PFS (HR 3.50), while PLR >180 was associated with worse OS (HR 2.37). In the 3-month landmark cohort (n=47), maintenance exposure remained associated with longer OS (HR 0.21), although this analysis remained vulnerable to residual selection bias.

CONCLUSION

Baseline GRIm was the most consistent candidate prognostic marker in this real-world ES-SCLC cohort. The study did not assess prediction of immunotherapy benefit, and prospective validation is warranted before treatment decisions are guided by GRIm.