The prognostic impact of peripheral blood eosinophil counts in metastatic renal cell carcinoma patients treated with nivolumab

Abstract

Abstract Background Although immune checkpoint inhibitors (ICIs) have gained approval for metastatic renal cell carcinoma (mRCC), the response rate is still limited. Therefore, it is urgent to explore novel and concise markers of responses to ICIs that can help assess clinical benefits. Recently, it has been noted that peripheral blood eosinophil counts is an independent factor correlated with clinical outcome of ICIs in some types of cancer. Methods We investigated peripheral blood absolute eosinophil counts (AECs) at baseline and 4 weeks after the initiation of nivolumab for mRCC patients between February 2016 to May 2022. In addition, we examined clinicopathological features including irAEs and analyzed the correlation between AECs and clinical efficacy of nivolumab. Results Of all patients, 22 patients (27.0%) developed irAEs. The median AECs in patients with irAEs was significantly higher at baseline and 4 weeks after the treatment compared to those without irAEs (p < 0.001 and p = 0.001, respectively). With the cutoff value of AECs of 329 cells/µL at 4 weeks after the treatment for prediction of irAEs, high-AECs groups had significantly higher number of responders compared with that in low-AECs group (p < 0.001). Accordingly, the progression-free survival (PFS) and overall survival (OS) were significantly better in patients with high-AECs group than those in low-AECs group (p = 0.03 and p = 0.009, respectively). Conclusion High AECs at 4 weeks after the treatment serve as the prominent surrogate marker associated with the incidence of irAEs and better clinical outcome in mRCC patients receiving nivolumab.