5PSQ-137 Prognostic role of haematological parameters in extended-stage small-cell lung cancer patients treated with atezolizumab in combination with chemotherapy

<h3>Background and Importance</h3> The neutrophil-lymphocyte ratio (NLR) and eosinophil count (EAR) have been proposed as possible prognostic markers in immunotherapy-treated patients with different tumour types. <h3>Aim and Objectives</h3> To determine the prognostic role of NLR and EAR in patients with extended-stage small-cell lung cancer (ES-SCLC) treated with atezolizumab in combination with chemotherapy. <h3>Material and Methods</h3> Retrospective observational study that included patients with ES-SCLC treated with atezolizumab+carboplatin+etoposide between September-2021-December-2023. Variables collected were: sex, age, Eastern Cooperative Oncology Group Stage Performance Status (ECOG PS), baseline brain or liver metastases, causes of treatment discontinuation, neutrophil-lymphocyte ratio (absolute neutrophil count/absolute lymphocyte count) and EAR at two time points (baseline and first radiological assessment), objective response rate (ORR) and median progression-free survival (PFS) and overall survival (OS). Statistical analysis: the Kaplan-Meier method was used for estimating the probability of survival. The log-rank test was used to determine the relationship between each variable and OS. Cox regression model was performed with the variables that had shown statistical significance. <h3>Results</h3> Thirty-seven patients were included, 67.6% male, mean age 65 years (±7.6). 18.9% had brain metastases, 40.5% liver metastases and 94.6% ECOG&lt;2. At the data cut-off date (August 2024), nine patients remained alive and two were still undergoing treatment. 56.7% discontinued treatment due to progression, 21.6% died, 8.1% had clinical deterioration and 5.4% due to toxicity. 43.2% had partial response, 24.3% stable disease, 21.6% progression and in the remainder response was not assessed. Median PFS and OS were 4 months (95% CI 3.1–4.9) and 8 months (95% CI 5.06–10.94), respectively. In univariate analysis, variables significantly associated with lower OS were: NLR≥3 at first radiological assessment (p&lt;0.001), baseline EAR &lt;90 (p=0.007), EAR at first radiological assessment&lt;40 (p=0.045) and the presence of brain metastases (p=0.043). In multivariate analysis, NLR&lt;3 was the only independent predictor variable of OS with median OS 10 months (95% CI:3.05–16.93) vs 5 months (95% CI:3.15–6.85); HR=0.25; p=0.017. <h3>Conclusion and Relevance</h3> NLR &lt;3 at the first radiological assessment was identified as an independent predictor of OS in patients with ES- SCLC treated with atezolizumab in combination with chemotherapy. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest