Immune checkpoint inhibitor (ICI)-based combination therapies are widely used as first-line treatment for metastatic renal cell carcinoma (mRCC); however, considerable variability in clinical outcomes persists. Therefore, the identification of reliable and easily applicable prognostic markers remains of significant clinical importance. This study aimed to evaluate the prognostic value of the Gustave Roussy Immune (GRIm) score in patients with mRCC treated with first-line ICI-based combination regimens.

In this retrospective, multicenter cohort study, patients with mRCC who received first-line ICI-based combination therapy were identified from the Turkish Oncology Group Kidney Cancer Consortium (TKCC) database. The GRIm score was calculated using pretreatment serum lactate dehydrogenase, serum albumin, and neutrophil-to-lymphocyte ratio. Patients were categorized into low (0–1) and high (2–3) GRIm score groups. The primary endpoints were time to treatment failure (TTF) and overall survival (OS).

A total of 78 patients were included, of whom 14 (17.9%) were classified in the high GRIm score group and 64 (82.1%) in the low GRIm score group. Patients with a high GRIm score had significantly shorter TTF and OS compared with those in the low GRIm score group (TTF: 5.8 vs. 11.0 months, p = 0.017; OS: 9.3 vs. 36.0 months, p = 0.001). The combined IMDC and GRIm model showed a modest numerical improvement in discrimination for OS compared with either model alone.

The GRIm score is significantly associated with survival outcomes in patients with mRCC treated with first-line ICI-based combination therapies. Given its simplicity and reliance on routinely available clinical parameters, the GRIm score may serve as a practical and accessible adjunct to existing prognostic models in clinical practice.