American College of Rheumatology ( ACR ) response rates attained early in the TCZ treatment period were maintained throughout the study : at Week 168 , JIA ACR 30 , 50 , 70 , 90 , and 100 response rates were 80.3 % , 80.3 % , 75.4 % , 60.7 % , and 18.0 % , respectively .