5PSQ-037 Peripheral blood biomarkers dynamics predict clinical response to pembrolizumab plus chemotherapy in patients with non-squamous metastatic non-small-cell lung cancer

Background and Importance Heterogeneity in response to immunotherapy in patients with advanced non-small-cell lung cancer (NSCLC) highlights the need to identify predictive biomarkers. Peripheral blood biomarkers have been associated with the prognosis in advanced NSCLC treated with immunotherapy. Aim and Objectives To analyse the correlation between the response to pembrolizumab plus chemotherapy and peripheral blood biomarker dynamics in patients with non-squamous metastatic NSCLC. Material and Methods Retrospective and observational study including all patients treated with pembrolizumab plus pemetrexed plus platinum-based chemotherapy from January 2020 to December 2021. Variables collected: sex, age, baseline Eastern Cooperative Oncology Group (ECOG) scale, and lymphocyte, neutrophil and eosinophil absolute counts (ALC, ANC and AEC, respectively) at three timepoints: baseline (before treatment), week 4 of treatment and first computerised tomography (CT) scan. Neutrophil-to-lymphocyte ratio (NLR) was calculated for each timepoint. Patients were classified as responders (partial response or stable disease) or non-responders (progression at first CT scan). Statistical analysis was performed with software SPSS 24.0. Results Sixty patients were included 76.7% were male with a median age of 62 years. 88.3% presented baseline ECOG Conclusion and Relevance Our results suggest that NLR behaves as a predictive biomarker of response to immunotherapy. ANC showed significant differences among responders and non-responders at week 4, and ALC at the first evaluation. AEC did not show correlation with response. References and/or Acknowledgements Conflict of Interest No conflict of interest.