Background: First-line NIVO+CABO met primary and secondary efficacy endpoints by improving progression-free survival (PFS; HR 0.51, P< 0.0001), overall survival (OS; HR 0.60, P = 0.0010), and objective response rate (ORR; 55.7% vs 27.1%; P< 0.0001) vs SUN in patients (pts) with aRCC in CheckMate 9ER (Choueiri et al. ESMO 2020). Efficacy benefits with NIVO+CABO vs SUN were consistent across prespecified subgroups including by IMDC risk group, and regardless of tumor PD-L1 expression (database lock for primary analysis, March 30, 2020). Updated analyses are needed to establish durability of benefit with first-line NIVO+CABO and assess outcomes in aRCC pts with sarcomatoid features (sRCC)—an aggressive histologic subtype associated with poor prognoses. Methods: In this phase III open-label trial, adults with confirmed aRCC (with a clear cell component including those with sRCC) were randomized 1:1 (stratified by IMDC risk score, tumor PD-L1 expression, geographic region) to NIVO 240 mg IV Q2W + CABO 40 mg PO QD vs SUN 50 mg PO (4 weeks of 6-week cycles). The primary endpoint was RECIST v1.1-defined PFS by blinded independent central review (BICR) in all randomized (intent-to-treat [ITT]) pts; secondary endpoints included OS, ORR by BICR, and safety. Pts with and without sRCC were identified by local pathology report, and outcomes in these pts were evaluated via prespecified supportive subset analyses. Results: The presence of sRCC was assessed in ITT pts (N = 651) at enrollment. Overall, 75 (11.5%) pts had sRCC and 557 (85.6%) did not; sRCC status was not reported in 19 pts (2.9%). Overall, 34 vs 41 pts with sRCC were randomized to NIVO+CABO vs SUN, respectively. At a median follow-up of 18.1 months, NIVO+CABO improved PFS, OS, and ORR in sRCC pts vs SUN (Table). Notable PFS, OS, and ORR benefits were observed with NIVO+CABO vs SUN in the subgroup of pts without sRCC. Median PFS was doubled, the risk of death was lower, and ORR was consistently higher with NIVO+CABO vs SUN regardless of sarcomatoid status. Key updated PFS, OS, response, and safety outcomes in the ITT population and in pts with and without sRCC will be reported with additional follow-up based on a September 10, 2020 database lock. Conclusions: NIVO+CABO demonstrated improved efficacy and prolonged survival vs SUN in previously untreated aRCC pts regardless of sarcomatoid status. Updated results with extended follow-up will assess the durability of outcomes in this trial. Clinical trial information: NCT03141177.

^aPts assessed for sRCC and were negative.

NR, not reached.