<qa>  What is a multicenter Phase II study?This is a multicenter, Phase II, randomized, double-blind, placebo-controlled, active comparator Cohort 1 only, parallel-group, dose-ranging study to evaluate the efficacy and safety of GDC-0853 in participants with moderate to severe active RA and an inadequate response to previous methotrexate MTX therapy Cohort 1 or MTX and tumor necrosis factor TNF therapy who may have also had exposure to no more than one non-TNF inhibitor biologic Cohort 2. 