BMS-986142 at 4, 10, and 30 mg/kg results in dose-dependent reductions of 26%, 43%, and 79% in clinically evident disease, respectively, at the end of the study. Interestingly, 4 mg/kg BMS-986142 provides an additive benefit in clinical scores (54% inhibition) when co-administered with MTX versus 19% inhibition with MTX alone. Co-administration of BMS-986142 at 4 mg/kg with MTX result in a 53% reduction in inflammation and bone resorption compared with 24% and 10%, respectively, with either drug alone. Furthermore, serum anti-collagen II IgG titers are significantly inhibited with 10 and 30 mg/kg BMS-986142. BMS-986142 also produces dose-dependent reductions in clinical scores when administration is delayed until the collagen booster on day 21. BMS-986142 doses of 2, 4, and 25 mg/kg in this therapeutic dosing regimen result in clinical score reductions of 17%, 37%, and 67%, respectively, at the end of the study.