Prognostic value of 1-year [18F]FDG-PET–CT-defined complete metabolic response in metastatic clear-cell renal cell carcinoma: a multicentre, observational cohort study in China

Background In metastatic clear-cell renal cell carcinoma (mccRCC), residual lesions on CT after immune checkpoint blockade (ICB)-based therapy often remain anatomically visible despite uncertain biological viability. In this study, we evaluated whether 1-year [ 18 F]fluorodeoxyglucose ([ 18 F]FDG)-PET–CT-defined complete metabolic response (CMR), assessed at a prespecified landmark among patients who remained progression free throughout the first treatment year, provides complementary prognostic information beyond CT-based response assessment. Methods In this multicentre, observational cohort study with prospective follow-up at eight tertiary hospitals in China, we included patients (≥18 years) with histologically confirmed mccRCC who received first-line ICB-based combination therapy, remained progression free per Response Evaluation Criteria in Solid Tumours (RECIST) version 1.1 throughout the first treatment year, and completed paired baseline and 1-year [ 18 F]FDG-PET–CT scans. Patients initiated first-line therapy between Jan 1, 2021, and Jan 31, 2024, and the analytical data cutoff was April 30, 2025. Response at the 1-year landmark was assessed using RECIST 1.1 and modified European Organisation for Research and Treatment of Cancer criteria. The primary endpoints were progression-free survival and overall survival from the 1-year landmark. All patients meeting prespecified eligibility criteria constituted the full analytical set for the primary endpoints. Findings Of 867 patients screened after baseline [ 18 F]FDG-PET–CT, 339 met the prespecified landmark eligibility criteria and formed the final 1-year landmark cohort. 268 (79%) of 339 patients were male and 71 (21%) were female. At the 1-year landmark, conventional CT identified complete response in 28 (8%) of 339 patients and [ 18 F] FDG-PET–CT identified CMR in 78 (23%) patients. Median follow-up from the 1-year landmark was 17·0 months (IQR 5·7–24·7). Median progression-free survival was 22·6 months (95% CI 20·0–not reached) in the CMR group versus 10·9 months (8·9–13·5) in the non-CMR group (hazard ratio [HR] 0·32, 95% CI 0·22–0·48; p