Background: NIVO has demonstrated significant benefit over IPI as adjuvant treatment in pts with resected stage IIIB–C or stage IV melanoma (AJCC v7). Combination NIVO + IPI has shown numerically longer survival than NIVO alone in pts with metastatic melanoma. CheckMate 915 evaluated adjuvant NIVO + IPI 1 mg/kg Q6W vs NIVO.

Methods: Pts aged ≥ 12 y with completely resected stage IIIB–D or stage IV melanoma (AJCC v8) were stratified by tumor PD-L1 expression and stage and treated with NIVO 240 mg Q2W + IPI 1 mg/kg Q6W (NIVO + IPI1) or placebo-controlled NIVO 480 mg Q4W alone for ≤ 1 y (NIVO + IPI were to be discontinued together). Dual endpoints were recurrence-free survival (RFS) in the PD-L1 < 1% and intent-to-treat populations. Distant metastasis-free survival (DMFS) in pts with stage III disease was an exploratory endpoint.

Results: Of 920 pts randomized to NIVO + IPI1 and 924 to NIVO alone, most had stage IIIB (31% vs 31%) or IIIC (53% vs 52%) disease and had undergone complete lymph node dissection (64% vs 64%). Pts treated with NIVO + IPI1 vs NIVO alone had a shorter median duration of therapy (7.6 vs 11.1 mo) and therefore, a lower median cumulative NIVO dose (3840 vs 6240 mg). At a minimum follow-up of 24 mo, RFS and DMFS did not differ between treatment groups (table). Grade 3/4 treatment-related adverse events (TRAEs) occurred in 33% of pts treated with NIVO+IPI1 and 13% with NIVO alone; any-grade TRAEs led to discontinuation of therapy in 32% vs 10% of pts, respectively. There were 4 treatment-related deaths (all with NIVO + IPI1).

Conclusions: The NIVO + IPI1 regimen did not result in RFS or DMFS improvement vs NIVO in stage IIIB–D/IV resectable melanoma; safety profiles were consistent with previous studies. NIVO 480 mg Q4W outcomes in CheckMate 915 were similar to previous NIVO results and reinforce NIVO as an adjuvant standard of care in a study population that included pts with and without complete lymphadenectomy.

NIVO 240 mg Q2W + IPI 1 mg/kg Q6W (ITT)NIVO 480 mg Q4W (ITT)NIVO 240 mg Q2W + IPI 1 mg/kg Q6W (tumor PD-L1 < 1%)NIVO 480 mg Q4W (tumor PD-L1 < 1%)
RFS     
24-mo rate 64.6% (95% CI, 61.3-67.7) 63.2% (95% CI, 59.9-66.4) 53.6% (95% CI, 48.0-58.8) 52.4% (95% CI, 46.8-57.7) 
Median, mo (events/pts) Not reached (327/920) Not reached (347/924) 33.2 (159/349) 25.3 (166/351) 
HR, NIVO + IPI1 vs NIVO 0.92 (97.295% CI, 0.77-1.09); P = 0.269  0.91 (95% CI, 0.73-1.14)  
DMFS in pts with stage III disease     
24-mo rate 75.4% (95% CI, 72.1-78.4) 77.4% (95% CI, 74.1-80.3) 67.9% (95% CI, 61.9-73.1) 68.4% (95% CI, 62.5-73.7) 
Median, mo (events/pts) Not reached (195/797) Not reached (194/798) Not reached (92/305) Not reached (96/307) 
HR, NIVO + IPI1 vs NIVO 1.01 (95% CI, 0.83-1.23)  0.94 (95% CI, 0.70-1.25)  
NIVO 240 mg Q2W + IPI 1 mg/kg Q6W (ITT)NIVO 480 mg Q4W (ITT)NIVO 240 mg Q2W + IPI 1 mg/kg Q6W (tumor PD-L1 < 1%)NIVO 480 mg Q4W (tumor PD-L1 < 1%)
RFS     
24-mo rate 64.6% (95% CI, 61.3-67.7) 63.2% (95% CI, 59.9-66.4) 53.6% (95% CI, 48.0-58.8) 52.4% (95% CI, 46.8-57.7) 
Median, mo (events/pts) Not reached (327/920) Not reached (347/924) 33.2 (159/349) 25.3 (166/351) 
HR, NIVO + IPI1 vs NIVO 0.92 (97.295% CI, 0.77-1.09); P = 0.269  0.91 (95% CI, 0.73-1.14)  
DMFS in pts with stage III disease     
24-mo rate 75.4% (95% CI, 72.1-78.4) 77.4% (95% CI, 74.1-80.3) 67.9% (95% CI, 61.9-73.1) 68.4% (95% CI, 62.5-73.7) 
Median, mo (events/pts) Not reached (195/797) Not reached (194/798) Not reached (92/305) Not reached (96/307) 
HR, NIVO + IPI1 vs NIVO 1.01 (95% CI, 0.83-1.23)  0.94 (95% CI, 0.70-1.25)  

Citation Format: Georgina V. Long, Dirk Schadendorf, Michele Del Vecchio, James Larkin, Victoria Atkinson, Michael Schenker, Jacopo Pigozzo, Helen J. Gogas, Stéphane Dalle, Nicolas Meyer, Paolo A. Ascierto, Shahneen Sandhu, Thomas Eigentler, Ralf Gutzmer, Jessica C. Hassel, Caroline Robert, Matteo Carlino, Anna Maria Di Giacomo, Marcus O. Butler, Eva Muñoz-Couselo, Michael P. Brown, Piotr Rutkowski, Andrew Haydon, Jean-Jacques Grob, Jacob Schachter, Paola Queirolo, Alexander Menzies, Sandra Re, Tuba O. Bas, Veerle de Pril, Daniel Tenney, Hao Tang, Jeffrey S. Weber. Adjuvant therapy with nivolumab (NIVO) combined with ipilimumab (IPI) vs NIVO alone in patients (pts) with resected stage IIIB-D/IV melanoma (CheckMate 915) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT004.