Phase III trial of adjuvant sunitinib in patients with high-risk renal cell carcinoma (RCC): Validation of the 16-gene Recurrence Score in stage III patients.

Abstract

4508 Background: Adjuvant therapy with sunitinib (SU) compared with placebo (PBO) prolonged disease-free survival (DFS) in 615 patients (pts) with high-risk RCC (hazard ratio [HR] 0.76; P= 0.03) in the S-TRAC trial. The 16-gene Recurrence Score (RS) was developed and validated to predict risk of recurrence of RCC after nephrectomy in 2 cohorts of stage I–III pts (Rini et al., Lancet Oncol 2015;16:676-85). We present further validation of RS results in high-risk stage III pts from S-TRAC. Methods: The study was prospectively designed with prespecified genes, algorithm, endpoints, analytical methods, and analysis plan using primary RCC tissues from 212 evaluable pts with informed consent. Gene expression was quantitated by RT-PCR; primary analysis focused on stage III (n = 193 pts). Time to recurrence (TTR) and DFS were analyzed using Cox proportional hazard regression. Results: Baseline characteristics were similar in SU and PBO arms and in pts with and without gene expression data; effect of SU was numerically similar to that in the entire trial (DFS HR 0.78, 95% CI 0.48–1.24; P= 0.29). RS predicted TTR and DFS in both treatment arms with the strongest results observed in PBO arm where high RS group had significantly higher risk (Table). Interaction of RS with treatment was not significant (TTR P= 0.192; DFS P= 0.219); however, the number of events was relatively low. Conclusions: The prognostic value of the 16-gene assay was confirmed in S-TRAC. RS is now validated with consistent results in 2 separate studies (level IB evidence). RS results may help identify patients at high risk who could derive higher absolute benefit from adjuvant treatment. The predictive value of RS to select patients for adjuvant SU requires further investigation in independent adjuvant trials. [Table: see text]