Percentage of subjects achieving at least 20% improvement from baseline (ACR20) in tender and swollen joint counts (ACR core set measures 1 and 2) and at least 20% improvement from baseline in the 3 of the 5 remaining ACR core set measures at EOT (up to Week 12) compared to placebo.

The ACR core set measures are:

1. Tender joint count
2. Swollen joint count
3. Subject Assessment of arthritis pain
4. Subject's Global Assessment of disease activity (SGA)
5. Physician's Global Assessment of disease activity (PGA)
6. Health Assessment Questionnaire Disability Index (HAQ-DI)
7. Acute Phase Reactant (i.e., hs-CRP - high sensitivity C-reactive protein)

Subjects in the Intent-to-Treat (ITT) population (subjects who received at least one dose of JTE-051 or placebo, and had at least one post-baseline efficacy assessment during the double-blind treatment period) with available efficacy assessment(s) results at EOT (up to Week 12).

Percentage of subjects achieving at least 20% improvement from baseline (ACR20) in tender and swollen joint counts (ACR core set measures 1 and 2) and at least 20% improvement from baseline in the 3 of the 5 remaining ACR core set measures at Week 12 compared to placebo.

The ACR core set measures are:

1. Tender joint count
2. Swollen joint count
3. Subject Assessment of arthritis pain
4. Subject's Global Assessment of disease activity (SGA)
5. Physician's Global Assessment of disease activity (PGA)
6. Health Assessment Questionnaire Disability Index (HAQ-DI)
7. Acute Phase Reactant (i.e., hs-CRP - high sensitivity C-reactive protein)

Subjects in the ITT population (subjects who received at least one dose of JTE-051 or placebo, and had at least one post-baseline efficacy assessment during the double-blind treatment period) with available efficacy assessment(s) results at Week 12.

Percentage of subjects achieving at least 50% improvement from baseline (ACR50) in tender and swollen joint counts (ACR core set measures 1 and 2) and at least 50% improvement from baseline in the 3 of the 5 remaining ACR core set measures at Week 12 compared to placebo.

The ACR core set measures are:

1. Tender joint count
2. Swollen joint count
3. Subject Assessment of arthritis pain
4. Subject's Global Assessment of disease activity (SGA)
5. Physician's Global Assessment of disease activity (PGA)
6. Health Assessment Questionnaire Disability Index (HAQ-DI)
7. Acute Phase Reactant (i.e., hs-CRP - high sensitivity C-reactive protein)

Subjects in the ITT population (subjects who received at least one dose of JTE-051 or placebo, and had at least one post-baseline efficacy assessment during the double-blind treatment period) with available efficacy assessment(s) results at Week 12.

Percentage of subjects achieving at least 70% improvement from baseline (ACR70) in tender and swollen joint counts (ACR core set measures 1 and 2) and at least 70% improvement from baseline in the 3 of the 5 remaining ACR core set measures at Week 12 compared to placebo.

The ACR core set measures are:

1. Tender joint count
2. Swollen joint count
3. Subject Assessment of arthritis pain
4. Subject's Global Assessment of disease activity (SGA)
5. Physician's Global Assessment of disease activity (PGA)
6. Health Assessment Questionnaire Disability Index (HAQ-DI)
7. Acute Phase Reactant (i.e., hs-CRP - high sensitivity C-reactive protein)

Subjects in the ITT population (subjects who received at least one dose of JTE-051 or placebo, and had at least one post-baseline efficacy assessment during the double-blind treatment period) with available efficacy assessment(s) results at Week 12.

The SDAI Scores indicate how active a patient's rheumatoid arthritis (RA) is currently. The SDAI is the sum of 5 outcome parameters: tender joint score (0 to 28), swollen joint score (0 to 28), Patient's Global Score of disease activity (0 to 10), Physician's Global Score of disease activity (0 to 10) and C-reactive protein (CRP, 0 to 10).General SDAI Score Interpretation is as follows:

0.0 - 3.3 Remission 3.4 - 11.0 Low Activity 11.1 - 26.0 Moderate Activity 26.1 - 86.0 High Activity

Subjects in the ITT population (subjects who received at least one dose of JTE-051 or placebo, and had at least one post-baseline efficacy assessment during the double-blind treatment period) with available efficacy assessment(s) results at Week 12.

The CDAI is a useful clinical composite score for following patients with rheumatoid arthritis (RA). The CDAI is the sum of 4 outcome parameters: tender joint score (0 to 28), swollen joint score (0 to 28), Patient's Global Score of disease activity (0 to 10) and Physician's Global Score of disease activity (0 to 10). The CDAI Score Interpretation is as follows:

0 to 2.8: Remission 2.9 to 10: Low Disease Activity 10.1 to 22: Moderate Disease Activity 22.1 to 76: High Disease Activity

Subjects in the ITT population (subjects who received at least one dose of JTE-051 or placebo, and had at least one post-baseline efficacy assessment during the double-blind treatment period) with available efficacy assessment(s) results at Week 12.

Disease Activity Score (DAS) modified to include 28 joint count (DAS28) consists of composite score of following variables: 28 tender joint count (TJC28) ranging from 0 to 28, 28 swollen joint count (SJC28) ranged from 0 to 28, C-reactive protein (CRP) (milligrams per liter) and subject's global assessment of disease activity (SGA) ranging from 0 (no disease activity) to 10 (extremely active disease). DAS28-CRP was calculated using following formula:

DAS28-CRP=0.56*square root (sqrt)(TJC28)+0.28*sqrt(SJC28)+0.36*natural log(CRP+1)+0.014*SGA+0.96.

DAS28-CRP ranged from 0.96-9.4, where lower scores indicated less disease activity and remission is DAS28-CRP <2.6.

A decrease in DAS28-CRP indicated an improvement in participant's condition.

Subjects in the ITT population (subjects who received at least one dose of JTE-051 or placebo, and had at least one post-baseline efficacy assessment during the double-blind treatment period) with available efficacy assessment(s) results at Week 12.

The HAQ-DI questionnaire assesses the participant's self-perception on the degree of difficulty [0 (without any difficulty), 1 (with some difficulty), 2 (with much difficulty), and 3 (unable to do)] in 8 functional area categories: (1) dressing and grooming; (2) arising; (3) eating; (4) walking; (5) hygiene; (6) reaching; (7) gripping; and (8) performing other daily activities. Scores from each functional area category (total 8 categories) were averaged to calculate the HAQ-DI score, which ranged from 0 (no disability) to 3 (severe disability). A decrease in HAQ-DI score indicated an improvement in the participant's condition.

Subjects in the ITT population (subjects who received at least one dose of JTE-051 or placebo, and had at least one post-baseline efficacy assessment during the double-blind treatment period) with available efficacy assessment(s) results at Week 12.

Subjects in the Safety Population (258, subjects who were randomly assigned to treatment and who received at least one dose of study drug). The number of subjects in the Safety Population is 258 subjects, which is 1 less than the Randomized Population of 259 subjects, since 1 randomized subject did not receive any study drug.

Subjects in the Safety Population (258, subjects who were randomly assigned to treatment and who received at least one dose of study drug). The number of subjects in the Safety Population is 258 subjects, which is 1 less than the Randomized Population of 259 subjects, since 1 randomized subject did not receive any study drug.

Subjects in the Pharmacokinetic (PK) population (received at least one dose of JTE-051 and have at least one usable JTE-051 plasma concentration measurement) with available trough plasma concentrations of JTE-051 at Week 12.