At week 12 , the brodalumab 140-mg and 280-mg groups had higher rates of ACR 20 than the placebo group ( 37 % [ P = 0.03 ] and 39 % [ P = 0.02 ] , respectively , vs. 18 % ) ; they also had higher rates of 50 % improvement ( ACR 50 ) ( 14 % [ P = 0.05 ] and 14 % [ P = 0.05 ] vs. 4 % ) .