This is a Phase 2, randomized, investigator and patient-blind, sponsor-unblinded, parallel group, placebo-controlled study to investigate the safety, tolerability, PK, and PD of ATI-450 plus methotrexate versus methotrexate alone in patients with moderate to severe RA with inadequate response to methotrexate. All subjects will be required to complete a safety follow up visit 30 days post last study medication administration.
