758P - Neutrophil to lymphocyte ratio (NLR) impact on the survival and response duration of patients with metastatic castration resistant prostate cancer (mCRPC) treated with abiraterone acetate (AA)

Abstract

The tumor microenvironment and inflammatory response are hallmarks of cancer progression. The NLR emerged as an indicator of the inflammatory state in patients with cancer, and has been negatively correlated with the prognosis of several solid tumors including mCRPC. The NLR is an available and easy to use tool and the authors assessed its role in the prognosis and response duration of patients treated with AA. Retrospectively evaluated clinical data of patients with mCRPC from a single high volume center, with disease evaluable according to the Prostate Cancer Clinical Trials Working Group 2 (PCWG2) criteria, that underwent at least 12 weeks of AA. NLR was calculated by dividing the absolute neutrophil count by the absolute lymphocyte count in the peripheral blood at baseline and at 12 weeks of treatment. NLR was stratified in two groups, > 5 and < 5. Overall Survival (OS) and Progression-free Survival (PFS) were defined according to the PCWG2 criteria. The correlation of median OS and PFS obtained using Kaplan-Meier curves with the NLR was tested through a multivariate Cox regression analysis. 112 patients were treated with AA between 01/01/2013 and 31/12/2015, 90 for at least 12 weeks. The average NLR was 4,35 ± 3,07 (1,15-22,10). 33 had a NLR > 5 (36,7%), with both groups characteristics balanced. Median OS was 16,6 months in the NLR > 5 group and 27,1 months in the NLR < 5 group (HR 0,507, p = 0,024). NLR remained predictive of a worse OS in a multivariate analysis that included pre-therapeutic prognostic factors. 21 patients (63,6%) with a NLR > 5 at baseline converted to < 5 at 12 weeks of treatment with AA, and this was associated with a trend for a better OS (10,5 vs 8,5 months, p = 0,197). Median PFS was 10,4 months in the NLR > 5 group and 9,7 months in the NLR < 5 group (p = 0,867). The NLR was prognostic in this analysis, with a NLR > 5 at baseline associated to a worse OS. There was no relation between NLR and response duration, with similar PFS in both groups. There was a trend for better OS in patients with a NLR > 5 at baseline that converted to < 5 at 12 weeks of treatment with AA. Further studies are warranted to validate NLR as a prognostic tool with the use of AA.