Evaluation of the Optimal MTX Dose as an Add-on Therapy to Adalimumab for RA Patients in Japan, South Korea and Taiwan

Inclusion Criteria

• Patients aged ≥18 years (≥20 years in Taiwan) at the time of informed consent
• Patients who meet the 1987 revised ACR criteria or 2010 ACR/EULAR criteria
• Patients who have RA within 2 years from initial diagnosis to informed consent
• Patients who were previously untreated with MTX, JAK inhibitor, or bDMARDs
• Patients who have disease activity of SDAI >11 at screening
• Patients who are no need for concomitant use of DMARDs other than hydroxychloroquine (only in South Korea and Taiwan) and study drugs during the study as judged by principal investigator/sub-investigator at screening
• Patients who are no need for concomitant use of corticoid steroid equivalent to >10 mg/day prednisolone during the study as judged by principal investigator/sub-investigator at screening.
• Female of child-bearing potential who can use appropriate contraceptive during the study, female in whom time from menopause to informed consent is ≥1 year, or female of no child-bearing potential through sterilization (bilateral tubal ligation, bilateral ovariectomy or hysterectomy, etc.)
• Virile male who can use appropriate contraceptive during the study
• Patients who can adequately understand this study procedures, and voluntarily consent in writing to take part in this study (consent of a legally-acceptable representative is also required for patients aged <20 years in Japan and aged <19 years in South Korea)

Exclusion Criteria

• Patients who currently have a malignant tumor, except for non-melanoma forms of skin cancer limited within epidermis, and uterine cervix cancer limited within epidermis
• Patients who have serious infections such as sepsis
• Patients who have active tuberculosis
• Patients who have a history or current complication of demyelinating disease such as multiple sclerosis
• Patients who have congestive heart failure
• Pregnant female, or female who intend to conceive during the study period
• Patients who have bone marrow depression and whom investigator considered ineligible
• Patients who have chronic liver disease and whom investigator considered ineligible, and who is positive for HBs antigen
• Patients who have nephropathy and whom investigator considered ineligible
• Lactating female
• Patients who have pleural effusion or ascites
• Patients with a known hypersensitivity to MTX or ADA
• Patients otherwise whom principal investigator/sub-investigator considered medically ineligible to participate in the study