ACR20 Responder Index: Composite of clinical, laboratory, and functional measures of rheumatoid arthritis. ACR20 Responder: had >=20% improvement from baseline in both 68 tender and 66 swollen joint counts and >=20% improvement in at least 3 of 5 criteria: participant's and physician's global assessment of disease activity, Health Assessment Questionnaire-Disability Index (HAQ-DI) (which measured participants' perceived degree of difficulty performing daily activities), joint pain, and C-reactive protein (CRP). Percentage of participants achieving ACR20 response=(number of ACR20 responders/number of participants treated)*100. All non-responders at Week 16 as well as all participants who discontinued study treatment at any time, for any reason, were defined as non-responders starting at that timepoint and going forward, including Week 24 endpoint.

All randomized participants with at least 5/68 tender joints and 5/66 swollen joints at baseline and with evaluable ACR20 data. If participant's CRP was missing, last postbaseline value was used. If ACR was missing after carrying forward CRP, last postbaseline ACR response was used. Data after Week 16 for Week 16 non-responders was not included.

ACR Responder Index: Composite of clinical, laboratory, and functional measures of rheumatoid arthritis. ACR50 Responder: had >=50% improvement from baseline in both 68 tender joint (TJ) and 66 swollen joint (SJ) counts and >=50% improvement in at least 3/5 criteria: participant's (Pt's) and physician's global assessment of disease activity, HAQ-DI (measured Pts' perceived degree of difficulty performing daily activities), joint pain, and CRP. Percentage of Pt achieving ACR50 response=(number (No) of ACR50 responders/No of Pts treated)*100. ACR70 Responder: had >=70% improvement from baseline in both TJ and SJ counts and >=70% improvement in at least 3 of same 5 criteria for ACR50. Percentage of Pts achieving ACR70 response=(No of ACR70 responders/No of Pts treated)*100. All non-responders at Week 16 as well as all Pts who discontinued study treatment at any time, for any reason, were defined as non-responders starting at that timepoint and going forward, including Week 24 endpoint.

All randomized participants with at least 5/68 TJ and 5/66 SJ at baseline and with evaluable ACR50 or ACR70 responder data. If participant's CRP was missing, last postbaseline value was used. If ACR was missing after carrying forward CRP, last postbaseline ACR response was used. Data after Week 16 for Week 16 non-responders was not included.

ACR-N is a continuous measure of clinical, laboratory, and functional outcomes in rheumatoid arthritis that characterizes percentage of improvement in disease activity from baseline based on ACR core set. Percentage of improvement was truncated to range of -100 to 100 to minimize impact of outliers (greater values indicate greater percent improvement). This index was calculated as minimum of a) percentage of improvement in TJ count, b) percentage of improvement in SJ count, or c) third highest percentage of improvement of remaining 5 ACR core criteria: If >=3 components of the 5 ACR core criteria were missing, then c) was set to missing; if any of 3 components a), b), or c) were missing, then ACR-N was set to missing. Least Squares (LS) means were calculated using analysis of covariance (ANCOVA) with treatment, region, tumor necrosis factor-inadequate responder treatment history, and disease-modifying anti-rheumatic drug (DMARD) background as fixed factors and baseline as a covariate.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable ACR-N data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

Tender joint count is the number of tender and painful joints determined for each participant by examination of 68 joints. Joints were assessed by pressure and joint manipulation on physical examination. Participants were asked for pain sensations on these manipulations and watched for spontaneous pain reactions. Any positive response on pressure, movement, or both is translated into a single tender-versus-nontender dichotomy. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable tender joint count data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

Swollen joint count is the number of swollen joints determined for each participant by examination of 66 joints. Joints were classified as either swollen or not swollen. Swelling was defined as palpable fluctuating synovitis of the joint. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable swollen joint count data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

Participant's assessment of their current arthritis pain using a visual analog scale (VAS) ranged from 0 millimeters (mm) (no pain) to 100 mm (worst possible pain). A decrease in pain score indicated an improvement in the participant's condition. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable participant's assessment of pain data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

Participant's assessment of their current arthritis disease activity using a visual analog scale (VAS) ranged from 0 millimeters (mm) (no arthritis activity) to 100 mm (extremely active arthritis). A decrease in disease activity score indicated an improvement in the participant's condition. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable participant's global assessment of disease activity data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

Physician's assessment of the participant's current arthritis disease activity using a visual analog scale (VAS) ranged from 0 millimeters (mm) (no arthritis activity) to 100 mm (extremely active arthritis). A decrease in disease activity score indicated an improvement in the participant's condition. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable physician's global assessment of disease activity data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

Disease Activity Score (DAS) modified to include 28 joint count (DAS28) consisted of composite score of following variables: tender joint count (TJC28), swollen joint count (SJC28), C-reactive protein (CRP) (milligrams per liter), and participant global assessment of disease activity using visual analog scale (VAS) (participant global VAS). 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*participant global VAS+0.96. Scores ranged 1.0-9.4, 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. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants, even if participant did not take assigned treatment, did not receive correct treatment, or otherwise did not follow protocol, with evaluable DAS28-CRP data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

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)] when dressing and grooming, arising, eating, walking, hygiene, reaching, gripping, and performing other daily activities. Scores for each functional area, which ranged from 0 (no disability) to 3 (severe disability), were averaged to calculate HAQ-DI. A decrease in HAQ-DI score indicated an improvement in the participant's condition. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable HAQ-DI data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

ACR20 Responder Index: Composite of clinical, laboratory, and functional measures of rheumatoid arthritis. ACR20 Responder: had >= 20% improvement from baseline in both 68 tender and 66 swollen joint counts and >=20% improvement in at least 3 of 5 criteria: participant's and physician's global assessment of disease activity, Health Assessment Questionnaire-Disability Index (HAQ-DI) (which measured participants' perceived degree of difficulty performing daily activities), joint pain, and C-reactive protein (CRP). The Kaplan-Meier estimator was used to summarize time to ACR20 response over the Treatment Period (24 weeks). The time to American College of Rheumatology 20% (ACR20) response (in weeks) is calculated as:

(Date of the first postbaseline visit during the Treatment Period meeting ACR20 response criteria - Date of first injection of study treatment + 1) / 7.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable ACR20 response data. Week 16 non-responders were counted as responders if they responded prior to Week 16. Otherwise, they were censored at the date of the Week 16 injection.

ACR20 Responder Index: Composite of clinical, laboratory, and functional measures of rheumatoid arthritis. ACR20 Responder: had >= 20% improvement from baseline in both 68 tender and 66 swollen joint counts and >=20% improvement in at least 3 of 5 criteria: participant's and physician's global assessment of disease activity, Health Assessment Questionnaire-Disability Index (HAQ-DI) (which measured participants' perceived degree of difficulty performing daily activities), joint pain, and C-reactive protein (CRP). The Kaplan-Meier estimator was used to summarize time to ACR20 response over the Treatment Period (24 weeks). The time to American College of Rheumatology 20% (ACR20) response (in weeks) is calculated as:

(Date of the first postbaseline visit during the Treatment Period meeting ACR20 response criteria - Date of first injection of study treatment + 1) / 7.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable ACR20 response data. Week 16 non-responders were counted as responders if they responded prior to Week 16. Otherwise, they were censored at the date of the Week 16 injection.

EULAR Responder index based on 28 joint count categorizes clinical response based on improvement since baseline in DAS28-CRP. Participants are categorized as EULAR responders or non-responders based on improvement of DAS28-CRP scores from baseline. EULAR28 responder is defined as either DAS28-CRP <=5.1 and DAS28-CRP change <-0.6; or DAS28-CRP >5.1 and DAS28-CRP change <-1.2. EULAR28 responder index is defined as good response: DAS28-CRP <=3.2 and DAS28-CRP change <-1.2; moderate response: DAS28-CRP change <-1.2 except cases defined in good response; or DAS28-CRP <=5.1 and DAS28-CRP change <-0.6 and >-1.2. EULAR Remission is defined as a DAS28-CRP score of <2.6.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable EULAR response data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

The SF-36 is a health-related survey that assesses participant's quality of life and consists of 36 questions covering 8 health domains: physical functioning, bodily pain, role limitations due to physical problems and emotional problems, general health, mental health, social functioning, vitality, and 2 component scores (mental [MCS] and physical health [PCS]). Domain scores calculated by summing each item for each domain and transforming scores into 0-100 scale; higher scores indicated better health status. MCS score consisted of social functioning, vitality, mental health, and role-emotional scales. PCS score consisted of physical functioning, bodily pain, role-physical, and general health scales. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants with at least 5/68 tender joints and at least 5/66 swollen joints at baseline and with evaluable SF-36 domain and summary scores. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

CRP is an indicator of inflammation. A negative change indicated an improvement in the participant's condition. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants with at least 5/68 tender joints and 5/66 swollen joints at baseline and with evaluable CRP data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

Cell-surface marker cluster designation (CD) 3 negative, CD20 positive (CD3-CD20+) defines total mature B cells. B-lymphocyte antigen CD20 is an activated-glycosylated phosphoprotein expressed on the surface of all mature B cells. Baseline B-cell count is determined by calculating the average of the 2 pretreatment B-cell counts obtained once during Days -28 through -7 and on Day 0. A positive or negative change indicated an increase or decrease, respectively in B-cell count. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants who received at least 1 dose of study treatment with evaluable absolute B-cell data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values. Data after Week 16 for Week 16 non-responders was not included.

Immunoglobulins, or antibodies, are large proteins used by the immune system to identify and neutralize foreign particles such as bacteria and viruses. Their normal blood levels indicate proper immune status. Change from baseline serum immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM) levels are reported. A negative change indicated a decrease in immunoglobulin levels. LS means were calculated using ANCOVA with treatment, region, tumor necrosis factor-inadequate responder treatment history, and DMARD background as fixed factors and baseline as a covariate.

All randomized participants who received at least 1 dose of study treatment with evaluable serum immunoglobulin (Ig) data. Modified last observation carried forward (mLOCF) was used to impute missing postbaseline values.

Population estimate of constant clearance as determined by population pharmacokinetics (PK) analysis. A 2-compartment model was used in PK modeling.

Participants who received at least 1 dose of LY2127399 with evaluable LY2127399 PK data.

LY2127399 anti-drug antibodies (ADA) were assessed at baseline, 1, 4, 16, and 24 weeks. Percentage of participants (Pts) with ADA=(number of Pts with treatment-emergent ADA/number of Pts assessed)*100. Pts with treatment-emergent ADA were Pts who had any sample from baseline up to and through Week 24 that was a 4-fold increase (2-dilution increase) in immunogenicity titer over baseline titer, or Pts who tested negative at baseline and positive post-baseline (at titer of ≥1:20).

All randomized participants who received at least 1 dose of study treatment.