Background: In part A of the CheckMate 914 trial, adjuvant nivolumab plus ipilimumab (NIVO+IPI) did not improve disease-free survival (DFS) vs placebo (PBO) in patients (pts) with localized renal cell carcinoma (RCC) at high risk of post-nephrectomy relapse (Motzer RJ, et al. Lancet 2023). Exploratory analyses were conducted to better understand outcomes in key pt subsets and with early NIVO+IPI discontinuation. Methods: Key study inclusion criteria were radical/partial nephrectomy with negative margins > 4 and ≤ 12 weeks before randomization; predominant clear cell histology; pathological TNM stage T2a (grade [G] 3/4) N0M0, T2b-T4 (any G) N0M0, or any pT (any G) N1M0; and no evidence of residual disease/metastases. Pts in part A were randomized 1:1 to NIVO 240 mg Q2W (× 12) + IPI 1 mg/kg Q6W (× 4) or equivalent PBO for 24 weeks or until recurrence/unacceptable toxicity. Primary endpoint is DFS per blinded independent central review. Exploratory analyses assessed DFS by key subsets including Fuhrman grade, sarcomatoid features (yes/no), PD-L1 expression, and NIVO+IPI exposure (≤ 6 cycles [1–2 IPI doses] vs > 6 cycles [3–4 IPI doses]). Safety was assessed by exposure. Results: 816 pts were randomized to adjuvant NIVO+IPI (N = 405) or PBO (N = 411). At 37.0 months median follow-up (min, 15.4 months), subset analyses suggested a DFS benefit for NIVO+IPI vs PBO in pts with Fuhrman grade 4 or sarcomatoid features. DFS by PD-L1 expression will be reported in the presentation. Pts who received > 6 NIVO+IPI cycles trended toward improved DFS vs pts receiving ≤ 6 NIVO+IPI cycles. Of the 102 pts who received ≤ 6 NIVO+IPI cycles, 3% had sarcomatoid features, and 20% had Fuhrman grade 4; treatment discontinuation in these pts was due to study drug toxicity (75%), unrelated adverse events (AEs; 6%), pt request (5%), recurrence (4%), consent withdrawal/non-compliance (4%), or other (6%), and most pts receiving ≤ 6 NIVO+IPI cycles were discontinued without initial dose delay (NIVO, 84%; IPI, 89%). In the group of patients who received ≤ 6 NIVO+IPI cycles, grade 1–2 all-cause AEs were reported in 35% of pts (grade ≥ 3, 63%) and 31% of pts discontinued treatment due to grade 1–2 all-cause AEs (grade ≥ 3, 44%). Conclusions: Exploratory analyses suggest that tumor grade and sarcomatoid features influence outcomes with adjuvant NIVO+IPI. Limited NIVO+IPI exposure (≤ 6 cycles) and discontinuation for low-grade AEs may have contributed to the lack of DFS benefit observed in CheckMate 914 part A. Clinical trial information: NCT03138512.

CI, confidence interval; HR, hazard ratio.