Background: In S0931, adjuvant treatment with the mTOR inhibitor everolimus respectively yielded disease-free survival (DFS) and overall survival (OS) hazard ratios (HR) of 0.85 (95% CI 0.71-1.00) and 0.90 (95% CI 0.71-1.13) in pts with resected, localized RCC. Previously, everolimus had been shown to be active in chromophobe RCC (chRCC; Tannir et al Eur Urol 2016) and papillary RCC (papRCC; Escudier et al Eur J Cancer 2016). We sought to evaluate the efficacy of everolimus within these non-clear cell subsets of EVEREST. Methods: 1545 adult pts with treatment-naïve, non-metastatic, fully-resected RCC at intermediate high- (pT1 G3-4 N0 to pT3a G1-2 N0) or very high-risk (pT3a G3-4 to pT4 G-any or N+) for recurrence were randomized 1:1 to 54 weeks of everolimus 10 mg PO daily or placebo within 12 weeks of radical or partial nephrectomy. Exploratory analyses of RFS and OS chromophobe and papillary subgroups were performed. Results: A total of 99 eligible pts had chRCC; 109 had papRCC (16 type I; 37 type II; 56 NOS). Median follow-up is 6.3 years. Pt characteristics were balanced between the 2 arms in each histological group. Thirty-four (34%) pts in the chRCC subgroup and 50 (46%) pts in the papRCC subgroup had very high-risk disease. Fewer pts completed all 54 weeks of everolimus in each subgroup compared to placebo (49% vs. 74% in the ChRCC subgroup and 46% vs. 71% in the papillary subgroup). DFS and OS for each subgroup are shown. Conclusions: Non-clear cell histology accounted for a considerable proportion (~13%) of S0931 pts. The estimated everolimus HRs for DFS and OS in the chRCC subset are consistent with the overall trial result, but those same modest HRs were not seen in papRCC, in contrast to prior reports of mTOR inhibitor activity in this subtype. Although inferences are limited by sample size and wide CIs, this is the largest experience in chRCC or papRCC among any adjuvant trials presented to date. Clinical trial information: NCT01120249.

HR for everolimus vs. placebo, 2-sided p-value from unadjusted Cox model. CI = confidence interval.