Median PFS for WT KRAS mCRC was 10.0 months [ 95 % confidence interval ( CI ) 9.3-11 .4 months ] for arm 1 and 8.6 months ( 95 % CI 7.5-9 .5 months ) for arm 2 ; hazard ratio ( HR ) = 0.80 ; 95 % CI 0.67-0 .95 ; P = 0.01 .