Among patients with BRAF wild-type tumors , the rate of confirmed objective response was 61 % ( 44 of 72 patients ) in the group that received both ipilimumab and nivolumab ( combination group ) versus 11 % ( 4 of 37 patients ) in the group that received ipilimumab and placebo ( ipilimumab-monotherapy group ) ( P < 0.001 ) , with complete responses reported in 16 patients ( 22 % ) in the combination group and no patients in the ipilimumab-monotherapy group .