Prognostic Impact of IMDC Category Shift From Baseline to Nivolumab Initiation in Metastatic Renal Cell Carcinoma: A Sub-Analysis of the MEET-URO 15 Study

•IMDC is the most important prognostic score for 1 line mRCC; it might be useful in subsequent lines.•492 pts were analyzed for IMDC changes from baseline to ≥2 line nivolumab start.•Longer mPFS and mOS were reached by stable favorable patients versus worsening to intermediate/poor.•Pts improving their IMDC class reached longer survival than those who remained stable/deteriorate.•IMDC category shift appears as a helpful prognostic tool for ≥2 line nivolumab in Mrcc. The International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) score is the most important prognostic score to stratify patients with metastatic renal cell carcinoma (mRCC), helping to guide treatment choice in first line. We hypothesized that IMDC change may also exert a prognostic role in subsequent lines of mRCC therapy. Meet-URO 15 is a multicenter Italian study of patients with mRCC receiving nivolumab as a second or subsequent line of therapy. This posthoc analysis aimed to evaluate the overall survival (OS) and progression-free survival (PFS) from nivolumab start as primary endpoints, overall response rate (ORR) and disease-control rate (DCR) as secondary endpoints, according to the change in the IMDC category from the first-line setting (baseline) to nivolumab start. Patients with available prognostic IMDC category information at baseline and before nivolumab were included. 492 patients were included in the analysis. At baseline, 165 (33.5%), 287 (58.3%), and 40 patients (8.2%) had favorable, intermediate, and poor IMDC categories, respectively. Before nivolumab, 364 patients (73.9%) remained in the same prognostic category as at baseline, 27 (5.5%) improved, and 101 (20.5%) deteriorated. Significantly longer mPFS (P = .01) and mOS (P < .01) were reached by patients with a stable favorable group compared to those worsening to intermediate/poor. A longer mOS was also achieved from intermediate/poor patients who improved their IMDC category before nivolumab compared to those remaining stable/worsening (P < .01 and P = .04, respectively). Maintaining IMDC category stability from baseline to nivolumab determined a more consistent DCR in favorable patients (P = .03). Overall, patients who improved their IMDC risk score reached better survival outcomes than those who remained stable/deteriorated. In our sub-analysis, the shift in the IMDC risk category appears to be a helpful prognostic tool for assessing the outcomes of patients with mRCC treated with ≥2nd line nivolumab. The I