The objective of this study is to evaluate the efficacy, safety and pharmacokinetics of ASP5094 in patients with rheumatoid arthritis (RA) treated with background methotrexate (MTX).

The study drug will be intravenously administered.

Inclusion Criteria:

• Subject has RA diagnosed according to the 1987 American College of Rheumatology (ACR) criteria or the 2010 ACR/European League Against Rheumatism (EULAR) criteria at least 6 months prior to screening.

• Subject meets the 1991 ACR Revised Criteria for the Classification of Global Functional Status in RA Class I, II, or III at screening.

• At screening and baseline, subject has active RA as evidenced by both of the following:

  • ≥ 6 tender/painful joints (using 68-joint assessment)
  • ≥ 6 swollen joints (using 66-joint assessment)

• Subject meets the criterion for a CRP level (Latex Agglutination method) at screening.

• Subject who has continuously received Methotrexate for at least 90 days prior to screening and who is able to continue a stable dose of Methotrexate from at least 28 days prior to screening throughout the study period.

Exclusion Criteria:

• Subject has deviated from the criteria for previous and concomitant treatment before baseline.
• Subject has an ongoing infection requiring antibiotics.
• Subject is determined to be an inadequate responder to a prior biologic disease modifying antirheumatic drugs (DMARDs) or Janus kinase (JAK) inhibitors.
• Subject has participated in previous ASP5094 clinical trial.
• Subject has participated in a clinical trial or post-marketing clinical study of another ethical drug or medical device within 12 weeks (84 days).
• Subject has another inflammatory arthritis than RA, or any other articular symptom which may affect on joint assessment.
• Subject meets any of the criteria for laboratory values at screening.
• Subject has a positive T-SPOT or QuantiFERON Gold test within 90 days prior to screening or at screening.
• Subject has a history of or concurrent malignant tumor.
• Subject has autoimmune disease except for RA or any severe, progressive, or uncontrolled renal, hepatic, hematological, gastrointestinal, metabolic, endocrine, pulmonary, cardiac, neurological, or mental illness.
• Subject has a history of clinically significant allergy.
• Subject has clinically significant abnormalities on 12-lead electrocardiogram (ECG) at screening.
• Subject has a history of Human Immunodeficiency Virus (HIV) infection.
• Subject had surgery within 30 days prior to screening or has a planned elective surgery.
• Subject has a wound that is currently healing at baseline.

Access to anonymized individual participant level data collected during the study, in addition to study-related supporting documentation, is planned for studies conducted with approved product indications and formulations, as well as products terminated during development. Studies conducted with product indications or formulations that remain active in development are assessed after study completion to determine if Individual Participant Data can be shared. Further details on Astellas' data sharing policy can be found at https://www.clinicaltrials.astellas.com/transparency/.

Access to participant level data is offered to researchers after publication of the primary manuscript (if applicable) and is available as long as Astellas has legal authority to provide the data.

Researchers must submit a proposal to conduct a scientifically relevant analysis of the study data. The research proposal is reviewed by an Independent Research Panel. If the proposal is approved, access to the study data is provided in a secure data sharing environment after receipt of a signed Data Sharing Agreement.