Response patterns to nivolumab differ from those seen with other approved targeted therapies.To investigate the efficacy of nivolumab in previously treated patients with advanced renal cell carcinoma who were treated beyond (Response Evaluation Criteria In Solid Tumors) RECIST progression.This was a subgroup analysis of patients treated with nivolumab in the phase 3 CheckMate 025 study. Patients continuing to tolerate therapy and exhibiting investigator-assessed clinical benefit were eligible to be treated beyond RECIST progression (TBP) and received therapy for ≥4 wk after first progression; patients not treated beyond RECIST progression (NTBP) received 0 wk to <4 wk of therapy after progression.Nivolumab 3mg/kg intravenously every 2 wk.Of 406 nivolumab-treated patients, 316 (78%) progressed by RECIST criteria. Of those who progressed, 48% were TBP, 52% were NTBP. Before being TBP, objective response rate (95% confidence interval) was 20% (14-28) and 14% (9-21) in patients TBP and NTBP, respectively. Differences in clinical characteristics assessed at first progression between patients TBP versus NTBP included better Karnofsky performance status, less deterioration in Karnofsky performance status, shorter time to response, lower incidence of new bone lesions, and improved quality of life. Postprogression, 13% of all patients TBP (20/153) had ≥30% tumor burden reduction including patients with preprogression and postprogression tumor measurements (n=142) and complete/partial response (28%, 8/29), stable disease (6%, 3/47), and progressive disease (14%, 9/66) as their best response before being TBP. Incidence of treatment-related adverse events in patients TBP was lower after (59%) versus before (71%) progression. Limitations included potential bias from the nonrandomized nature of the analysis.A subset of patients with advanced renal cell carcinoma and RECIST progression experienced tumor reduction postprogression with nivolumab, and had an acceptable safety profile. Clinical judgment remains essential when switching therapy. ClinicalTrials.gov Identifier: NCT01668784.A subset of patients with advanced renal cell carcinoma and disease progression may continue to benefit from nivolumab treatment beyond progression as evidenced by tumor reduction postprogression and an acceptable safety profile.