RT Journal Article SR Electronic T1 4CPS-012 Platelet to lymphocyte ratio (PLR) as biological marker of interest in immunotherapy JF European Journal of Hospital Pharmacy JO Eur J Hosp Pharm FD British Medical Journal Publishing Group SP A27 OP A28 DO 10.1136/ejhpharm-2023-eahp.60 VO 30 IS Suppl 1 A1 Toledo Davia, MA A1 Labrador Andújar, N A1 Rubio Salvador, AR A1 Blázquez Romero, C A1 Torralba Fernández, L A1 Jiménez Méndez, C A1 Prieto Galindo, R A1 Aguado Barroso, P A1 Gómez Fernández, E A1 Moya Gomez, P YR 2023 UL http://ejhp.bmj.com/content/30/Suppl_1/A27.3.abstract AB Background and Importance Inflammation plays a major role in the progression of neoplasms such as non-small-cell lung cancer (NSCLC), so it is vitally important to find biomarkers that are easily applicable and reproducible in routine clinical practice that allow us to classify patients according to their forecast.Aim and Objectives To analyse the inflammatory marker platelet/lymphocyte ratio (PLR) as a predictor of efficacy in immunotherapy treatments; to assess whether there is a relationship between PLR value and response to treatment.Material and Methods Retrospective and observational study of patients diagnosed with NSCLC and treated with pembrolizumab in a tertiary hospital, from January 2018 to December 2021. We collected demographic variables (sex and age), ECOG, histology, presence of metastases, PD-L1 expression and previous treatments. Progression-free survival (PFS) and overall survival (OS) were calculated by the Kaplan-Meier method and log-rank as hypothesis testing.; PLR (absolute platelet count/absolute lymphocyte count) was calculated and PLR=200 was considered the cut-off point. Cox regression test was used to assess the influence of PLR on treatment efficacy.Results Seventy-three patients treated with pembrolizumab (80.8% male, n=59) and median age 65 [83-37] years. Adenocarcinoma histology was 90% (n=66); 40 patients ECOG=0, 31 patients ECOG=1 and 2 patients ECOG=2; 26 patients PD-L1<50%, 19 patients PD-L1>50% and for 28 patients it was unknown; 12 patients CNS metastases and 22 patients had liver/bone metastases. Significant differences were obtained in the group of patients with liver/bone metastases in PFS with median of 6.3 (2.9-9.6) CI 95% vs 17.3 (11.4-23.2) CI 95% months (p=0.03), and in the group of patients with CNS metastases in OS with a median of 9.6 (1.2-17.9) CI 95% vs at 24.9 (18.6-31.2) 95% CI months (p=0.003). Median PFS was 15.6 [10.15-21.1] 95% CI for PLR <200 vs 9.97 [2.86-17.1] 95% CI months for PLR >200 (p=0.04); median OS was 26.25 [19.87-32.64] 95% CI for PLR <200 vs 11.31 [3.86-18.79] 95% CI months for PLR >200 (p=0.001). Cox regression test: HR=1.001 (p=0.017) for PFS and HR=1.002 (p=0.003) for OS.Conclusion and Relevance PLR and the presence of metastases correlates with PFS and OS. PLR, with a cut-off point =200, appears useful as a prognostic biomarker for patients with NSCLC treated with pembrolizumab; higher PLR values, result in lower PFS and OS (HR>1 in PFS and OS).Conflict of Interest No conflict of interest