Study of Two Doses of ABX464 in Participants With Moderate to Severe Rheumatoid Arthritis

Phase IIa Randomized, Double Blind, Placebo Controlled, Multiple Dose Study on ABX464 in Combination With Methotrexate (MTX), in Patients With Moderate to Severe Active Rheumatoid Arthritis Who Have Inadequate Response to MTX or/and to Anti-Tnfα, or Intolerance to Anti-Tnfα

This Phase IIa study aims at investigating the safety and tolerability of 2 dose-levels of ABX464 administered daily in combination with methotrexate (MTX) in patients with moderate to severe active Rheumatoid Arthritis (RA) who had an inadequate response to MTX or/and to one or more anti- tumor necrosis factor alpha (TNFα) therapies.

This is a randomized, double-blind, placebo-controlled, multicenter study. The study will consist of 3 phases: a screening phase, a treatment phase, and a follow-up phase.

Approximately 60 participants with active Rheumatoid Arthritis will be randomly assigned to receive placebo, 50mg ABX464 or 100mg ABX464 during the treatment phase.

The maximum period of active treatment will be 12 weeks. The maximum duration of study participation will be 17 weeks.

Participant safety will be monitored throughout the study. In addition, several experimental and clinical endpoints will be assessed to obtain information on preliminary efficacy.

Inclusion Criteria:

• Patient with a confirmed and documented diagnosis of adult-onset rheumatoid arthritis, for at least 12 weeks, according to the revised 2010 American College of Rheumatology- European League Against Rheumatism (ACR-EULAR) classification criteria, including at least one positive criteria among the following: Rheumatoid Factor (RF), Anti-Citrullinated Peptide Antibody (ACPA) or bone erosion;
• Swollen joint count (SJC) of ≥ 4 (28-joint count) and tender joint count (TJC) ≥4 (28-joint count) at screening;
• Patient with a moderate to severe disease activity score Disease Activity Score (28 joints) C-Reactive Protein [DAS28 CRP] ≥ 3.2 and C-reactive Protein (CRP) ≥ 5 mg/L (≥ 4.76 nmol)/L) at screening;
• Patient who had an inadequate response (IR), or failed either methotrexate (MTX) or/and anti- Tumor Necrosis Factor alpha (TNFα) therapy (both administered for at least 12 weeks before IR) or were intolerant to anti- TNFα therapy.

Exclusion Criteria:

• Patient with a known positive anti-double stranded deoxyribonucleic acid (DNA [anti-dsDNA]) and confirmed diagnosis of systemic lupus erythematosus (SLE);
• Patient with known active infections at screening such as CytoMegaloVirus (CMV), herpes virus and/or recent infectious hospitalization;
• Acute, chronic or history of clinically relevant pulmonary, cardiovascular, hepatic, pancreatic or renal functional abnormality, encephalopathy, neuropathy or unstable Central Nervous System (CNS) pathology such as seizure disorder, angina or cardiac arrhythmias, active malignancy or any other clinically significant medical problems as determined by physical examination and/or laboratory screening tests and/or medical history;
• Acute, chronic or history of immunodeficiency or other autoimmune disease;
• Patient previously treated with any non-anti-TNF biological Disease-Modifying AntiRheumatic Drugs (bDMARDs), and targeted DMARDs (tDMARDS) prior to baseline.