Final Overall Survival Analysis and Organ-Specific Target Lesion Assessments with Two-Year Follow-Up in CheckMate 9ER: Nivolumab Plus Cabozantinib Versus Sunitinib for Patients with Advanced Renal Cell Carcinoma.

350 Background: First-line nivolumab plus cabozantinib (N+C) demonstrated superiority over sunitinib (SUN) in the primary disclosure of the phase 3 CheckMate 9ER trial (NCT03141177; 10.6 months minimum follow-up; Choueiri TK et al. N Engl J Med 2021) in patients (pts) with advanced renal cell carcinoma (aRCC). Here, we report the preplanned final overall survival (OS) analysis with updated efficacy and safety in intent-to-treat (ITT) pts, and an exploratory assessment of target lesions by organ site after extended follow-up. Methods: Pts with aRCC (clear cell component) were randomized to N 240 mg every 2 weeks + C 40 mg once daily vs SUN 50 mg once daily (4 weeks of 6-week cycles). The primary endpoint was RECIST v1.1–defined progression-free survival (PFS) by blinded independent central review (BICR) in ITT pts; secondary endpoints included OS, objective response rate (ORR) by BICR, and safety. The preplanned final OS analysis was set to occur after observing 254 events. Maximal reduction of target lung, lymph node, kidney, and liver lesions were evaluated per BICR via post hoc exploratory analyses. Results: After 25.4 months minimum follow-up (median, 32.9 months) for OS in ITT pts, a total of 271 OS events occurred, and N+C continued to demonstrate OS improvement vs SUN (N = 323 vs 328; median 37.7 vs 34.3 months; HR 0.70 [95% CI 0.55–0.90]). PFS (median 16.6 vs 8.3 months; HR 0.56 [95% CI 0.46–0.68]) and ORR (55.7% [95% CI 50.1–61.2] vs 28.4% [95% CI 23.5–33.6]) benefits were maintained with N+C vs SUN, and 12.4% (N+C) vs 5.2% (SUN) of pts had a complete response. Median duration of response was 23.1 months with N+C vs 15.1 months with SUN. A higher percentage of pts experienced any reduction and ≥30% reduction from baseline with N+C vs SUN in target lesions at all organ sites assessed (Table). Among all treated pts, 97.2% (N+C; N = 320) vs 93.1% (SUN; N = 320) had a treatment-related adverse event (TRAE) of any grade (65.0% vs 54.1% had a grade ≥ 3 TRAE). Conclusions: N+C continued to provide survival improvement vs SUN among ITT pts in the final OS analysis, additionally PFS and ORR benefits with N+C were sustained with minimum 2-year follow-up. A higher proportion of pts experienced tumor shrinkage benefit with N+C vs SUN across all 4 organ sites assessed. No new safety signals emerged with extended follow-up in either arm. These results highlight N+C as a first-line treatment for pts with aRCC. Clinical trial information: NCT03141177. [Table: see text]