Sorafenib Versus Observation Following Radical Metastasectomy for Clear-cell Renal Cell Carcinoma: Results from the Phase 2 Randomized Open-label RESORT Study.

Background: In selected metastatic renal cell carcinoma (mRCC) patients, radical metastasectomy followed by observation is a potential strategy. It is still to be defined whether systemic therapy should be administered following metastasectomy.

Objective: To assess the potential benefit of postoperative treatment with sorafenib compared with observation alone after radical metastasectomy in mRCC patients.

Design, Setting, And Participants: The RESORT trial was a multicenter, randomized, open-label, phase 2 study conducted between November 2012 and November 2017 in Italy. Patients with clear-cell mRCC pretreated with nephrectomy and undergoing radical metastasectomy (three or fewer lesions) were eligible for the study. Patients were randomized (1:1) within 12 wk from metastasectomy to sorafenib (standard dose 400 mg twice daily) or observation for a maximum of 52 wk. Stratification factors were interval from nephrectomy, site, and number of lesions. Overall, 76 patients were screened and 69 were randomized: 33 were assigned to sorafenib and 36 to observation. The primary endpoint was recurrence-free survival (RFS). Secondary endpoints were overall survival and the safety profile.

Outcome Measurements And Statistical Analysis: RFS curves were estimated with the Kaplan-Meier method, and the log-rank test was used to statistically compare the curves.

Results And Limitations: At a median follow-up of 38 mo, median RFS was 37 mo (95% confidence interval [CI] 20-not available [NA]) in the observation arm versus 21 mo (95% CI 11-NA) in the sorafenib arm (log-rank test p = 0.404), with 12-, 24-, and 36-mo RFS probability of 74% versus 63%, 59% versus 49%, and 50% versus 41%, respectively, in the observation versus the sorafenib arm. Any-grade adverse event (AE) rates were 84% in the sorafenib arm and 31% in the observation arm; grade ≥3 AE rates were 22% and 3% in the sorafenib and the observation arm, respectively, with a rate of treatment discontinuation for AEs of 19% in the sorafenib arm.

Conclusions: This prospective study showed that systemic treatment with sorafenib did not increase RFS as compared with observation in mRCC patients following radical metastasectomy.

Patient Summary: This article reports the clinical outcome of patients with metastatic renal cell carcinoma treated with sorafenib or managed with an observation-alone strategy after the radical surgery of metastases. We found that sorafenib did not improve the patient outcome in terms of relapse-free survival in this selected population.