ACR20 is calculated as a 20% improvement from Baseline in Tender Joint Count 68 (TJC68) and Swollen Joint Count 66 (SJC66) and a 20% improvement in 3 of the following 5 measures: Patient's Global Assessment of Arthritis Disease Activity (PtGA) (visual analogue scale (VAS) with values from 0=best to 100=worst), Physician Global Assessment of Arthritis Disease Activity (PhGA) (VAS with values from 0=best to 100=worst), Patient Assessment of Arthritis Pain (VAS with values from 0=no pain and 100=most severe pain), Health Assessment Questionnaire-Disability Index (HAQ-DI) (ranges from 0 to 3 where 0 = least difficulty and 3 = extreme difficulty) and an acute-phase reactant (high sensitivity C-reactive Protein mg/L (hsCRP)). For the purpose of all analyses up to week 12, the placebo arms were pooled into a single placebo arm to primarily serve as a reference for the comparison of active treatment arms.

ACR20 is calculated as a 20% improvement from Baseline in Tender Joint Count 68 (TJC68) and Swollen Joint Count 66 (SJC66) and a 20% improvement in 3 of the following 5 measures: Patient's Global Assessment of Arthritis Disease Activity (PtGA) \[visual analogue scale (VAS) with values from 0=best to 100=worst\], Physician Global Assessment of Arthritis Disease Activity (PhGA) (VAS with values from 0=best to 100=worst), Patient Assessment of Arthritis Pain (VAS with values from 0=no pain and 100=most severe pain), Health Assessment Questionnaire-Disability Index (HAQ-DI) (ranges from 0 to 3 where 0 = least difficulty and 3 = extreme difficulty) and an acute-phase reactant \[high sensitivity C-reactive Protein milligram per liter (mg/L) (hsCRP)\]. For the purpose of all analyses up to week 12, the placebo arms were pooled into a single placebo arm to primarily serve as a reference for the comparison of active treatment arms.

Blood samples were collected for markers which may influence rheumatoid arthritis. Target engagement biomarkers included soluble GM-CSF complexed to GSK3196165. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Analysis was performed using repeated measures analysis adjusted for GM-CSF - Complex log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Analysis was performed on Intent-to-Treat (ITT) Population which consisted of all participants who were randomized to treatment and who received at least one dose of study treatment. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Predictive biomarkers included analysis of 14-3-3 ETA Protein, S100 CBP A8 and A9. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Analysis was performed using repeated measures analysis adjusted for 14-3-3 ETA Protein (mg/L) and S100 CBP A8 and A9 log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Predictive biomarkers included analysis of Amyloid A. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Analysis was performed using repeated measures analysis adjusted for Amyloid A log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles). Data has been presented for only those time points at which the samples were collected.

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Predictive biomarkers included analysis of Chemokine (C-C Motif) Ligand 17 (CL17), Chemokine (C-X-C Motif) Ligand 13 (CL13), Interleukin 6, Macrophage-Derived Chemokine (MDC). Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Analysis was performed using repeated measures analysis adjusted for CL17, CL13, Interleukin 6, MDC log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles). Data has been presented for only those time points at which the samples were collected.

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Predictive biomarkers included analysis of Chitinase 3 Like 1 and MMP-3. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Analysis was performed using repeated measures analysis adjusted for Chitinase 3 Like 1 and MMP-3 log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Blood samples were collected and analyzed for markers that may be predictive of rheumatoid arthritis disease activity. Cartilage biomarkers included analysis of ARGS Neo-Epitope, Citrullinated MMP-Degraded Vimentin (CMDV), MMP-Degraded C Reactive Protein (CRP), MMP-Degraded Type I Collagen (MD1C), MMP-Degraded Type II Collagen (MD2C), MMP-Degraded Type III Collagen (MD3C). Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Analysis was performed using repeated measures analysis adjusted for ARGS Neo-Epitope, Citrullinated MMP-Degraded Vimentin, MMP-Degraded CRP, MMP-Degraded Type I Collagen, MMP-Degraded Type II Collagen and MMP-Degraded Type III Collagen log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Whole blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Flow cytometry assessment included assessment of Helper/Suppressor. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Analysis was performed using repeated measures analysis adjusted for Helper/Suppressor log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Whole blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Flow cytometry assessment included assessment of cluster of differentiation (CD)16+CD56+, CD19, CD3, CD3+CD4+. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Repeated measures analysis adjusted for CD16+CD56+, CD19, CD3, CD3+CD4+, CD3+CD8+ and T Cell B Cell NKL log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Whole blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Flow cytometry assessment included assessment of CD3+CD8+ and T Cell B Cell NKL. Baseline was defined at Day 1. Change from Baseline was calculated by subtracting the post-dose value from the Baseline value. Analysis was performed using repeated measures analysis adjusted for CD3+CD8+ and T Cell B Cell NKL log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Whole blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Flow cytometry assessment included assessment of CD3+ CD4+, CD3+ CD8+ and CD3+. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Analysis was performed using repeated measures analysis adjusted for CD3+ CD4+, CD3+ CD8+ and CD3+ Number of Cells (10\^6/L) log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Whole blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Flow cytometry assessment included assessment of CD3+CD4+CD25+CD127- and CD3+CD4+foxP3+CD25+CD127-. Baseline was defined at Day 1. Change from Baseline was calculated by subtracting the post-dose value from the Baseline value. Analysis was performed using repeated measures analysis adjusted for CD3+CD4+CD25+CD127- and CD3+CD4+foxP3+CD25+CD127-Number of Cells (10\^6 cells/L) log(Baseline value), treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. T Helper Cell Panel included analysis of CD45+3+8-4+CCR6+CXCR3+38+DR+, CD45+3+8-4+CCR6+CXCR3-38+DR+, CD45+3+8-4+CCR6-CXCR3+38+DR+, CD45+3+8-4+CCR6-CXCR3-38+DR+, CD45+CD3+CD8-CD4+, CD45+CD3+CD8-CD4+CCR6+CXCR3+, CD45+CD3+CD8-CD4+CCR6+CXCR3-, CD45+CD3+CD8-CD4+CCR6-CXCR3+ and CD45+CD3+CD8-CD4+CCR6-CXCR3-. Baseline was defined at Day 1. Change from Baseline was calculated by subtracting the post-dose value from the Baseline value. Analysis was performed using repeated measures analysis adjusted for T Helper Cell Panel Events (EVENTS) Baseline value, treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Whole blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Flow cytometry assessment included assessment of CD14-HLA-DR+CD11cbr+CD123-, CD14br+CD16+, CD14br+CD16- and CD14lo+CD16br+. Baseline was defined at Day 1. Change from Baseline was calculated by subtracting the post-dose value from the Baseline value. Analysis was performed using repeated measures analysis adjusted for CD14-HLA-DR+CD11cbr+CD123-, CD14br+CD16+, CD14br+CD16- and CD14lo+CD16br+ (10\^3/Liter) baseline value, treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Whole blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Flow cytometry assessment included assessment of CD14-CD16+CD66b+ cell. Baseline was defined at Day 1. Change from Baseline was calculated by subtracting the post-dose value from the Baseline value. Analysis was performed using repeated measures analysis adjusted for CD14-CD16+CD66b+ (10\^6/Liter) baseline value, treatment group, disease duration (\<=2 or \>2 years), visit and treatment group by visit interaction. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Complement biomarkers included analysis of Complement C3 and Complement C4. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Complement biomarkers included analysis of Complement C4a, Complement C5a, Complement Split Factor SC5b-9 and Soluble CD163. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Mechanistic biomarkers included analysis of Interleukin 1 Beta, Interleukin 10, Interleukin 15, Interleukin 17 Alpha, Interleukin 17F, Interleukin 8 and Tumor Necrosis Factor. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. NA indicates that data is not available since 100% of the data was below limit of quantification at all time points. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Safety biomarkers included analysis of 3B-Cholestenoic Acid and Surfactant Protein D. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

Blood samples were collected and analyzed for markers which may be predictive of rheumatoid arthritis disease activity. Safety biomarker included analysis of KL-6 Antigen. Baseline was defined at Day 1. Change from Baseline was calculated as ratio of Baseline value to post-dose value. Only those participants with data available at the specified data points were analyzed (represented by n= X in the category titles).

DAS28 is a modification of the original DAS and is based on a count of 28 swollen and tender joints and is used to evaluate a participant's response to treatment. DAS 28 CRP utilizing joint scores from the following 28 joints: elbows, shoulders, elbow, wrists, metacarpal- phalangeal I-V, proximal interphalangeal I-V and knees and is calculated using the following formula: DAS28 (CRP) = 0.56\*√(TJC28) +0.28\*√(SJC28)+0.014\*GH+0.36\*ln(CRP+1)+0.96. Where TJC - Tender joint Count, SJC= Swollen Joint Count, (GH=participant assessment of disease activity using a 100 millimeter \[mm\] visual analogue scale with 0 = best, 100 = worst) and CRP= C reactive Protein (in \[milligrams/liter\] mg/L). It ranges between 0.96 and 8.61. High score (worse outcome) and low scores (better outcome). ITT population comprised of all participants who were randomized to treatment and who received at least one dose of study treatment (GSK3196165 or placebo).

Blood samples were collected at pre-dose on Days 1, 8, 15, 29, 57 and 71; and at any time during visit on Days 3, 74, 85, 106, 127 and 155. PK parameters were calculated by non-compartmental analysis using the concentration data after last dosing (Day 71). Only those participants whose parameters could be determined were analyzed. PK Population included all GSK3196165-treated participants from whom PK samples were collected and analyzed.

Blood samples were collected at pre-dose on Days 1, 8, 15, 29, 57 and 71; and at any time during visit on Days 3, 74, 85, 106, 127 and 155. PK parameters were calculated by non-compartmental analysis using the concentration data after last dosing (Day 71). NA indicates data was not available as geometric mean and/or 95 percent confidence interval could not be calculated when number of participant was not sufficient.

Blood samples were collected at pre-dose on Days 1, 8, 15, 29, 57 and 71; and at any time during visit on Days 3, 74, 85, 106, 127 and 155. PK parameters were calculated by non-compartmental analysis using the concentration data after last dosing (Day 71).

Blood samples were collected at pre-dose on Days 1, 8, 15, 29, 57 and 71; and at any time during visit on Days 3, 74, 85, 106, 127 and 155. PK parameters were calculated by standard non-compartmental analysis from the concentration data after last dosing (Day 71). NA indicates data was not available as 95 percent confidence interval could not be calculated when number of participant was not sufficient.

An AE is any untoward medical occurrence in a clinical investigation participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. Any untoward event resulting in death, life threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity, congenital anomaly/birth defect, any other situation according to medical or scientific judgment that may not be immediately life-threatening or result in death or hospitalization but may jeopardize the participant or may require medical or surgical intervention or event associated with liver injury and impaired liver function were categorized as SAE. AESI included serious infections including serious respiratory infections and tuberculosis and opportunistic infections, neutropenia (grade 3 or 4), respiratory events, pulmonary alveolar proteinosis, hypersensitivity reactions including anaphylaxis and injection site reactions.