Grade 3 to 5 adverse events occurred in 44.9 % ( 95 % CI ; 35.8 % -54.4 % ) of patients in the ipilimumab plus sargramostim group vs 58.3 % ( 95 % CI , 49.0 % -67.2 % ) of patients in the ipilimumab-alone group ( 2-sided P = .04 ) .