Prognostic Nutrition Index as Predictor for Nivolumab Monotherapy in Advanced Gastric Cancer Patients with Peritoneal Metastases.

Abstract Although nivolumab shows survival benefits for patients with advanced gastric cancer (AGC), predictive biomarkers for nivolumab treatment in AGC remain unclear, especially in the case of peritoneal metastases. Therefore, this study investigated the clinical significance of the prognostic nutrition index (PNI), reflecting the host nutritional status and immunity, in AGC patients undergoing nivolumab monotherapy. This study retrospectively analyzed 53 AGC patients who received nivolumab between October 2017 and February 2021. Among them, 35 patients with peritoneal metastases were reviewed to investigate the relationship between the PNI and oncological outcomes. The PNI was calculated as 10 × serum albumin level (g/dl) + 0.005× total lymphocyte count (per mm3) at the first administration of nivolumab. With a median follow-up duration of 2.0 (0.3 − 13.5) months, the median overall survival (OS) was 2.0 months. The overall response and disease-control rates were 0.0% and 20.0%, respectively. Among the 35 patients, 13 patients were identified as a high-PNI group. In the univariate analysis, the high-PNI group showed a significantly longer PFS and OS than the low-PNI group. In the multivariate analysis, the high-PNI was independently associated with a longer PFS (p = 0.021) and OS (p = 0.022). The PNI can be useful for predicting PFS and OS in AGC patients with peritoneal metastases. However, further studies are required to validate these results in AGC and new strategies are needed to improve the outcome for AGC patients with peritoneal metastases.