Prognostic Impact of Baseline Neutrophil-to-Eosinophil Ratio in Patients With Metastatic Renal Cell Carcinoma Treated With Nivolumab Therapy in Second or Later Lines

Background Inflammation is a crucial component in carcinogenesis. The neutrophil-to-eosinophil ratio (NER) has been studied as a biomarker of prognosis and predictive of response in metastatic renal cell carcinoma (mRCC). In the present study, we evaluated the relevance of baseline NER on the progression-free survival (PFS) and overall survival (OS) outcomes in real-world patients with mRCC treated with nivolumab in second or subsequent lines. We also assessed the association of baseline NER with objective response, as well as with toxicity and histology. Methods In this multicenter retrospective analysis of patients with mRCC treated with nivolumab, the last systemic absolute neutrophil and eosinophil count before treatment with nivolumab was used to calculate the NER. An additive Cox proportional hazards model was used to identify the cut-off point for NER considering PFS and the patients were allocated into low and high NER groups. Median OS and median PFS were estimated using the Kaplan-Meier estimator, and survival curves of groups were compared using the log-rank test. Univariable and multivariable Cox regression models were used to study OS and PFS and Fisher’s exact test was performed to evaluate the association of NER with the response, toxicity, and histology. Results The 49 analyzed patients had a median follow-up of nine months. The NER cut-off was established at 48, locating 29 patients in the low NER group (NER < 48) and 20 in the high NER group (NER ≥ 48). Median PFS and median OS were significantly shorter in patients with high NER versus low NER (3 vs. 30 months (p < 0.001) and 6 vs. 24 months (p = 0.002), respectively). Multivariable analyses showed that NER (HR 3.92 (95% CI: 1.66-9.23), p = 0.002) was an independent factor for PFS and that NER (HR 3.85 (95% CI: 1.33-11.17), p = 0.013) and progressive disease (HR 5.62 (95% CI: 1.88-16.83), p = 0.002) were independent factors for OS. NER was significantly associated with objective response rate (ORR) (NER ≥ 48-12.5% vs. NER < 48-87.5%, p = 0.003), immune-related adverse events (irAEs) (NER ≥ 48-10.0% vs. NER < 48-42.9%, p = 0.014), and tumor’s histology as patients of high NER group had more non-clear cell carcinoma than low NER group (35.0% vs. 7.4%, p = 0.017). Conclusion Our real-world data analysis of NER in patients with mRCC confirmed the prognostic value of this biomarker, supporting clinical utility in predicting survival. Results also suggested an association between lower NER and better ORR, and that irAEs occur more frequently in patients with a lower NER. However, further large-scale prospective studies are needed to confirm these findings and to validate this biomarker.