Evolocumab treatment for 12 weeks resulted in significant ( p < 0.001 ) mean ( 95 % confidence interval ) dose-related reductions in Lp ( a ) compared to control : 29.5 % ( 23.3 % to 35.7 % ) and 24.5 % ( 20.4 % to 28.7 % ) with 140 mg and 420 mg , dosed every 2 and 4 weeks , respectively , with no plateau of effect .