Prognostic immunotherapy score (PIS) in patients with advanced urothelial carcinoma treated with pembrolizumab: real-world data and validation from ARON-2 dataset

: Recent years have seen the development and advent of novel combinatorial strategies based on immunotherapy, and immune checkpoint inhibitor (ICI) - based treatment has established itself as a mainstay in the treatment of metastatic urothelial carcinoma (UC). Herein, we aimed to validate the prognostic value of a previously developed score, the Prognostic Immunotherapy Score (PIS), including female sex, Eastern Cooperative Oncology Group Performance Status (ECOG-PS) and liver metastases, in patients treated with pembrolizumab for advanced UC from the ARON-2 dataset. We retrospectively analyzed clinical data from Metastatic UC patients diagnosed at age ≥ 18 years. Patients progressing or recurring after platinum-based therapy were included, and treated with pembrolizumab from January 1st, 2016, to December 31st, 2023, in 68 oncological centers from 21 Countries. The Kaplan-Meier analysis was used to calculate the median follow-up. Cox proportional hazard models were used to compare the multivariable effects on patients' survival and to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). A survival receiver operating characteristic (ROC) analysis was exploited in relation to OS and PFS in patients stratified by the presence of 0, 1 or ≥ 2 risk factors and OS with 0, 1 or ≥ 2 risk factors in patients stratified by age, tumor histology, site and time to metastatic disease. The comparison between subgroups was performed with the Fisher exact test. We included 1040 patients from the ARON-2 dataset. We further stratified patients based on the three previously published risk factors: female sex, ECOG-PS = 2 and liver metastases; 526 patients (51%) had 0 risk factors, 408 patients (39%) had 1 factor and 106 patients (10%) had ≥ 2 risk factors. At univariate and multivariate analyses, bone metastases, synchronous metastatic disease and our PIS model based on female sex, liver metastasis, and poor performance status were significantly associated with both OS and PFS. Our findings validate the PIS as a practical scoring model using sex, ECOG-PS, and liver metastasis to stratify survival outcomes in advanced urothelial carcinoma treated with pembrolizumab, supporting more personalized treatment decisions.