ATI-450 Plus Methotrexate (MTX) Versus Placebo Plus MTX in Participants With Moderate to Severe Active Rheumatoid Arthritis (RA)

Phase 2b, Randomized, Multicenter, Double-blind, Parallel Group, Placebo Controlled, Dose Ranging Study to Investigate the Efficacy, Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Multiple Doses of ATI-450 Plus Methotrexate (MTX) Versus Placebo Plus MTX in Patients With Moderate to Severe Active Rheumatoid Arthritis (RA) Who Have Had an Inadequate Response to MTX Alone

This study evaluates ATI-450 plus MTX versus placebo plus MTX in participants with moderate to severe active RA who have had an inadequate response to MTX alone.

This is a Phase 2b, randomized, multicenter, double-blind, parallel group, placebo controlled, dose ranging study to investigate the efficacy, safety, tolerability, pharmacokinetics, and pharmacodynamics of multiple doses of ATI-450 plus MTX versus placebo plus MTX in participants with moderate to severe active RA who have had an inadequate response to MTX alone.

Inclusion Criteria:

• Able to comprehend and be willing to sign the Institutional Review Board (IRB)/Independent Ethics Committee (IEC) approved participant ICF prior to administration of any study-related procedures.
• Diagnosis of adult-onset RA as defined by the 2010 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria.
• Have active moderate to severe RA at Screening.
• A minimum of 12 weeks on MTX with a stable MTX dose.

Exclusion Criteria:

• Current acute or chronic immunoinflammatory disease other than RA which may impact the course or assessment of RA.
• Uncontrolled non-immunoinflammatory disease that may place the participant at increased risk during the study or impact the interpretation of results (eg, previous malignancy, recurrent infection, previous venous thromboembolism).
• Participant has experience with > 2 biologics, > 1 JAK inhibitor, or a combination of 1 biologic experience and 1 JAK inhibitor.
• Currently receiving corticosteroids at doses > 10 mg/day of prednisone (or equivalent) or have been receiving an unstable dosing regimen of corticosteroids within 2 weeks of screening.