A Study to Compare Upadacitinib (ABT-494) Monotherapy to Methotrexate (MTX) Monotherapy in Adults With Rheumatoid Arthritis (RA) Who Have Not Previously Taken Methotrexate

The objectives of Period 1 were the following:

* To compare the safety and efficacy of upadacitinib 7.5 mg once daily (QD) monotherapy (for participants in Japan only), 15 mg QD monotherapy, and 30 mg QD monotherapy versus weekly methotrexate monotherapy for the treatment of signs and symptoms of RA in methotrexate-naïve adults with moderately to severely active RA;
* To compare the efficacy of upadacitinib 15 mg QD monotherapy and upadacitinib 30 mg QD monotherapy versus weekly methotrexate monotherapy for prevention of structural progression in methotrexate-naïve adults with moderately to severely active RA.

The objective of Period 2 is to evaluate the long-term safety, tolerability, and efficacy of upadacitinib 7.5 mg QD (for participants in Japan only), 15 mg QD, and 30 mg QD in adults with RA who have completed Period 1.

This study includes 2 periods (a 48-week double-blind treatment period and a long-term extension period) and a Japan substudy. In Period 1 participants will be randomized in a 1:1:1 ratio to treatment Groups 2, 3, and 4 below, except for participants from Japan, who will be randomized in a 2:1:1:1 ratio to Groups 1, 2, 3, and 4:

* Group 1: Upadacitinib 7.5 mg once daily (QD) monotherapy (participants in Japan only)
* Group 2: Upadacitinib 15 mg QD monotherapy
* Group 3: Upadacitinib 30 mg QD monotherapy
* Group 4: Methotrexate monotherapy

Rescue therapy is defined for Weeks 12 through 24, Week 26, and Weeks 36 through 40. Starting at Week 12 through Week 24, participants who do not achieve ≥ 20% improvement in both tender joint count (TJC) and swollen joint count (SJC) compared with baseline at two consecutive visits will continue on their blinded therapy and the Investigator should optimize (initiate or increase) background RA medications: non-steroidal anti-inflammatory drug(s) (NSAIDs), corticosteroids (oral ≤ 10 mg/day prednisone equivalent or prednisone equivalent ≤ 0.5 mg/kg/day for 3 consecutive days) and/or low-potency analgesics.

Rescue therapy for participants who meet the following criteria at Week 26 are as follows:

Participants who do not achieve clinical remission (CR) based on Clinical Disease Activity Index (CDAI) (defined as a CDAI score ≤ 2.8):

* but achieve ≥ 20% improvement in both TJC and SJC compared with baseline will continue on blinded study drug and the Investigator should optimize (initiate or increase) background RA medications: NSAIDs, corticosteroids (oral ≤ 10 mg/day prednisone equivalent and up to 2 local injections), low-potency analgesics and conventional synthetic disease-modifying anti-rheumatic drug(s) (csDMARDs) (only 1 of the following: sulfasalazine, hydroxychloroquine or chloroquine) throughout the remainder of Period 1 and until the study is unblinded.
* and do not achieve ≥ 20% improvement in both TJC and SJC compared with baseline and originally assigned to methotrexate will be re-randomized in a 1:1 ratio to receive blinded upadacitinib 15 mg QD or upadacitinib 30 mg QD (participants in Japan will be randomized 1:1:1 to receive upadacitinib 7.5 mg QD, 15 mg QD, or 30 mg QD) while continuing methotrexate treatment in a blinded manner until the study is unblinded. Participants originally assigned to upadacitinib will add methotrexate 10 mg/week (7.5 mg for Japan) to upadacitinib in a blinded manner and will remain on upadacitinib plus methotrexate 10 mg/week (7.5 mg for Japan) until the study is unblinded.

Starting at Week 36 through Week 40, participants who do not achieve ≥ 20% improvement in both TJC and SJC compared with baseline at two consecutive visits will continue on their blinded therapy and the Investigator should optimize (initiate or increase) background RA medications: NSAIDs, corticosteroids (oral ≤ 10 mg/day prednisone equivalent or prednisone equivalent ≤ 0.5 mg/kg/day for 3 consecutive days and up to 2 local injections), low-potency analgesics and csDMARDs (only 1 of the following: sulfasalazine, hydroxychloroquine or chloroquine).

Participants who complete the Week 48 visit (end of Period 1) will enter the long-term extension, Period 2 (212 weeks) and continue study treatment per assignment at the end of Period 1 in a blinded fashion. When the last participant completes the last visit of Period 1 (Week 48), study drug assignment in both periods may be unblinded, and participants will be dispensed study drug in an open-label fashion until the completion of Period 2. Starting with Protocol Amendment 6, participants receiving upadacitinib 15 mg and 30 mg QD will receive open-label upadacitinib 15 mg QD, and participants receiving methotrexate will receive open-label methotrexate.

A global analysis will be conducted for the comparisons of the primary and secondary efficacy endpoints between the upadacitinib 15 mg QD and 30 mg QD treatment groups versus the methotrexate treatment group for all participants (excluding the Japan specific upadacitinib 7.5 mg treatment group). Analyses will be conducted separately for United States (US)/Food and Drug Administration (FDA), European Union (EU)/European Medicines Agency (EMA), and Japan/Pharmaceuticals and Medical Devices Agency (PMDA) regulatory purposes, each according to a pre-specified sequence of primary and ranked secondary endpoints.

A separate Japan sub-study analysis will be conducted for the comparisons of the efficacy endpoints between the upadacitinib 7.5 mg QD, 15 mg QD, and 30 mg QD treatment groups versus the methotrexate treatment group for participants enrolled in Japan only.

Eligibility Criteria:
Inclusion Criteria:

* Duration of symptoms consistent with RA for ≥ 6 weeks who also fulfill the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria for RA.
* Naïve to Methotrexate (MTX) or, if already on MTX, have received no more than 3 weekly MTX doses with requirement to complete a 4-week MTX washout before the first dose of study drug.
* Participants with prior exposure to conventional synthetic disease-modifying anti-rheumatic drugs(csDMARDs) other than MTX may be enrolled if completed the washout period.
* Participant meets both of the following minimum disease activity criteria:

  -≥ 6 swollen joints (based on 66 joint counts) and ≥ 6 tender joints (based on 68 joint counts) at Screening and Baseline Visits.
* high sensitivity C reactive protein (hsCRP) ≥ 5 mg/L (central lab, upper limit of normal \[ULN\] 2.87 mg/L at Screening Visit.
* Greater than or equal to 1 bone erosion on x-ray (by local reading) OR in the absence of documented bone erosion, both positive rheumatoid factor (RF) and positive anti-cyclic citrullinated peptide (anti CCP) autoantibodies are required at Screening.
* Stable dose of non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen, oral corticosteroids (equivalent to prednisone ≤ 10 mg/day), or inhaled corticosteroids for stable medical conditions are allowed but must have been at a stable dose ≥ 1 week prior to the first dose of study drug.

Exclusion Criteria:

* Intolerant to Methotrexate (MTX).
* Prior exposure to any Janus kinase (JAK) inhibitor (including but not limited to tofacitinib, baricitinib, and filgotinib).
* Prior exposure to any biologic disease-modifying anti-rheumatic drugs (bDMARDs).
* History of any arthritis with onset prior to age 17 years or current diagnosis, inflammatory joint disease other than RA (including but not limited to gout, systemic lupus erythematosus, psoriatic arthritis, axial spondyloarthritis including ankylosing spondylitis and non-radiographic axial spondyloarthritis, reactive arthritis, overlap connective tissue diseases, scleroderma, polymyositis, dermatomyositis, fibromyalgia \[currently with active symptoms\]. Current diagnosis of secondary Sjogren's Syndrome is permitted.
* Has been treated with intra-articular, intramuscular, intravenous, trigger point or tender point, intra-bursa, or intra-tendon sheath corticosteroids in the preceding 8 weeks prior to the first dose of study drug.