• Number of Participants With a 20% Improvement From Baseline in Their American College of Rheumatology (ACR) Score (ACR20) at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  The ACR score was based on improvement from baseline in tender (TJC) and swollen joint counts (SJC). A participant had achieved ACR20 if he experienced >=20% improvement from baseline in TJC and SJC and a >=20% improvement from baseline in 3 out of 5 of the following assessments: participant pain assessment on a 100 millimeter (mm) visual analog scale (VAS), participant global assessment on a 100 mm VAS scale, physician global assessment on a 100 mm VAS scale, participant self-assessed disability, and C-reactive protein.
  
  

• Number of Participants With a 20% Improvement From Baseline in Their American College of Rheumatology (ACR) Score (ACR20) at Weeks 4, 8, 12, 16, and 20 [ Time Frame: Baseline and Weeks 4, 8, 12, 16, and 20 ] [ Designated as safety issue: No ]
  The ACR score was based on improvement from baseline in tender (TJC) and swollen joint counts (SJC). A participant had achieved ACR20 if he experienced >=20% improvement from baseline in TJC and SJC and a >=20% improvement from baseline in 3 out of 5 of the following assessments: participant pain assessment on a 100 millimeter (mm) visual analog scale (VAS), participant global assessment on a 100 mm VAS scale, physician global assessment on a 100 mm VAS scale, participant self-assessed disability, and C-reactive protein.
  
  
• Number of Participants With a 50% Improvement From Baseline in Their ACR Score (ACR50) at Weeks 4, 8, 12, 16, 20, and 24 [ Time Frame: Baseline and Weeks 4, 8, 12, 16, 20, and 24 ] [ Designated as safety issue: No ]
  The ACR score was based on improvement from baseline in tender (TJC) and swollen joint counts (SJC). A participant had achieved ACR50 if he experienced >=50% improvement from baseline in TJC and SJC and a >=50% improvement from baseline in 3 out of 5 of the following assessments: participant pain assessment on a 100 millimeter (mm) visual analog scale (VAS), participant global assessment on a 100 mm VAS scale, physician global assessment on a 100 mm VAS scale, participant self-assessed disability, and C-reactive protein.
  
  
• Number of Participants With a 70% Improvement From Baseline in Their ACR Score (ACR70) at Weeks 4, 8, 12, 16, 20, and 24 [ Time Frame: Baseline and Weeks 4, 8, 12, 16, 20, and 24 ] [ Designated as safety issue: No ]
  The ACR score was based on improvement from baseline in tender (TJC) and swollen joint counts (SJC). A participant had achieved ACR70 if he experienced >=70% improvement from baseline in TJC and SJC and a >=70% improvement from baseline in 3 out of 5 of the following assessments: participant pain assessment on a 100 millimeter (mm) visual analog scale (VAS), participant global assessment on a 100 mm VAS scale, physician global assessment on a 100 mm VAS scale, participant self-assessed disability, and C-reactive protein.
  
  
• Median ACRn at Weeks 4, 8, 12, 16, 20, and 24 [ Time Frame: Weeks 4, 8, 12, 16, 20, and 24 ] [ Designated as safety issue: No ]
  ACRn = the largest integer n for which a participant (par.) met the criteria requiring an improvement of n%. ACRn is a measure characterizing percent (%) improvement from baseline (IFBL). A par. with an ACRn of X had an improvement of >=X% in tender/swollen joints (TJC/SJC), and an improvement of >=X% in 3 of the 5 parameters (patient [pt] pain assessment, pt global assessment [GA], physician GA, pt self-assessed disability, acute phase reactant). ACRn = minimum(TJC % IFBL, SJC % IFBL, composite measure % IFBL). Composite measure % IFBL is the 3rd highest value of % IFBL for the 5 parameters.
  
  
• Mean Disease Activity Score Based on 28 Joints (DAS28) at Weeks 4, 8, 12, 16, 20, and 24 Using C-reactive Protein (CRP) as the Acute Phase Reactant (APR) [ Time Frame: Weeks 4, 8, 12, 16, 20, and 24 ] [ Designated as safety issue: No ]
  The DAS28 is a clinical index of rheumatoid arthritis disease activity (DA) that combines information from swollen and tender joints (jts.), the APR, and general health (patient global assessment). The following jts. were assessed on both sides of the body: shoulder, elbow, wrist, metacarpophalangeal (5 per side), proximal interphalangeal (5 per side), and knee. The level of DA can be interpreted as low (DAS28<=3.2), moderate (3.2<DAS28<=5.1), or high (DAS28>5.1); total score, 0-9.4. A DAS28 <2.6 corresponds to remission. APRs are a class of proteins that are useful markers for inflammation.
  
  
• Change From Baseline in DAS28 at Weeks 4, 8, 12, 16, 20, and 24 Using CRP as the Acute Phase Reactant [ Time Frame: Baseline and Weeks 4, 8, 12, 16, 20, and 24 ] [ Designated as safety issue: No ]
  The DAS28 is a clinical index of RA disease activity that combines information from swollen joints, tender joints, the acute phase reactant, and general health (patient global assessment). Change from baseline in DAS28 is calculated as the Week 4, 8, 12, 16, 20, and 24 values minus the baseline value.
  
  
• Mean DAS28 at Weeks 4, 8, 12, 16, 20, and 24 Using Erythrocyte Sedimentation Rate (ESR) as the Acute Phase Reactant [ Time Frame: Weeks 4, 8, 12, 16, 20, and 24 ] [ Designated as safety issue: No ]
  The DAS28 is a clinical index of rheumatoid arthritis disease activity (DA) that combines information from swollen and tender joints (jts.), the APR, and general health (patient global assessment). The following jts. were assessed on both sides of the body: shoulder, elbow, wrist, metacarpophalangeal (5 per side), proximal interphalangeal (5 per side), and knee. The level of DA can be interpreted as low (DAS28<=3.2), moderate (3.2<DAS28<=5.1), or high (DAS28>5.1); total score, 0-9.4. A DAS28 <2.6 corresponds to remission. APRs are a class of proteins that are useful markers for inflammation.
  
  
• Change From Baseline in DAS28 at Weeks 4, 8, 12, 16, 20, and 24 Using ESR as the Acute Phase Reactant [ Time Frame: Baseline and Weeks 4, 8, 12, 16, 20, and 24 ] [ Designated as safety issue: No ]
  The DAS28 is a clinical index of RA disease activity that combines information from swollen joints, tender joints, the acute phase reactant, and general health (patient global assessment). Change from baseline in DAS28 is calculated as the Week 4, 8, 12, 16, 20, and 24 values minus the baseline value.
  
  
• Number of Participants With the Indicated European League Against Rheumatism (EULAR) Response at Weeks 4, 8, 12, 16, 20, and 24 Using CRP as the Acute Phase Reactant [ Time Frame: Weeks 4, 8, 12, 16, 20, and 24 ] [ Designated as safety issue: No ]
  The DAS28-based EULAR response criteria were used to measure individual response as none, good, and moderate, depending on the extent of change from baseline and the level of disease activity reached. Good responders: change from baseline >1.2 with DAS28 <=3.2; moderate responders: change from baseline >1.2 with DAS28 <=3.2 to >5.1 or change from baseline >0.6 to <=1.2 with DAS28 <=3.2 to <=5.1); non-responders: change from baseline <=0.6 or change from baseline >0.6 and <=1.2 with DAS28 >5.1.
  
  
• Number of Participants With the Indicated European League Against Rheumatism (EULAR) Response at Weeks 4, 8, 12, 16, 20, and 24 Using ESR as the Acute Phase Reactant [ Time Frame: Weeks 4, 8, 12, 16, 20, and 24 ] [ Designated as safety issue: No ]
  The DAS28-based EULAR response criteria were used to measure individual response as none, good, and moderate, depending on the extent of change from baseline and the level of disease activity reached. Good responders: change from baseline >1.2 with DAS28 <=3.2; moderate responders: change from baseline >1.2 with DAS28 <=3.2 to >5.1 or change from baseline >0.6 to <=1.2 with DAS28 <=3.2 to <=5.1); non-responders: change from baseline <=0.6 or change from baseline >0.6 and <=1.2 with DAS28 >5.1.
  
  
• Number of Participants Classified as Responders at Week 24 According to the Self-Assessed Health Assessment Questionnaire Disability Index (HAQ-DI) [ Time Frame: Week 24 ] [ Designated as safety issue: No ]
  The HAQ-DI is a 20-question instrument used to assess the degree of difficulty a participant had in accomplishing tasks in 8 functional areas (FAs): dressing, arising, eating, walking, hygiene, reaching, gripping, and errands/chores. Responses for each FA were scored from 0 (no difficulty) to 3 (inability to perform a task). The total score (range of 0-3) was calculated by adding the 8 individual FA scores, then dividing this sum by the total number of components answered. Responders were defined as participants achieving an improvement from baseline in the HAQ-DI score at Week 24 of >=0.22.
  
  
• Number of Participants With Clinical Remission at Week 24 [ Time Frame: Week 24 ] [ Designated as safety issue: No ]
  Participants achieving clinical remission were defined as those with a low disease activity, i.e., DAS28 score (using CRP) <2.6 at Week 24.
  
  
• Change From Baseline in Tender Joint Count at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  Change from baseline in tender joint count was calculated as the Week 24 count minus the baseline count. A total of 68 joints were assessed. Joints were classified as either tender or not tender by an independent assessor, who had documented experience in performing joint assessments.
  
  
• Change From Baseline in Swollen Joint Count at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  Change from baseline in swollen joint count was calculated as the Week 24 count minus the baseline count. A total of 66 joints were assessed. Joints were classified as either swollen or not swollen by an independent assessor, who had documented experience in performing joint assessments.
  
  
• Change From Baseline in the Participant-assessed Pain Score at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  A horizontal VAS of 100 mm was used to report the participant's level of joint pain. The scale ranged from 0 (no pain) to 100 (unbearable pain). Participants were instructed to draw a vertical line through the horizontal line to indicate how much joint pain they had. The distance from the "no pain" end to the vertical line drawn by the participant was the joint pain score. Change from baseline was calculated as the Week 24 value minus the baseline value.
  
  
• Change From Baseline in Participant-assessed Global Disease Score at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  The participant used a horizontal VAS of 100 mm for overall assessment of disease. The scale ranged from 0 (very well) to 100 (very poor). Participants were instructed to draw a vertical line through the horizontal line to indicate the state of the arthritis. The distance from the "very well" end to the vertical line drawn by the participant was the global disease assessment score. Change from baseline in participant-assessed global disease was calculated as the Week 24 value minus the baseline value.
  
  
• Change From Baseline in the Physician-assessed Global Disease Score at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  The physician used a horizontal VAS of 100 mm for overall assessment of disease. The scale ranged from 0 (very well) to 100 (very poor). Physicians were instructed to draw a vertical line through the horizontal line to indicate the state of the arthritis. The distance from the "very well" end to the vertical line drawn by the participant was the global disease assessment score. Change from baseline in the physician-assessed global disease was calculated as the Week 24 value minus the baseline value.
  
  
• Change From Baseline in HAQ-DI Score at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  The self-assessed HAQ-DI is a 20-question instrument used to assess the degree of difficulty a participant had in accomplishing tasks in 8 functional areas (FAs): dressing, arising, eating, walking, hygiene, reaching, gripping, and errands/chores. Responses for each FA were scored from 0 (no difficulty) to 3 (inability to perform a task). The total score (range of 0-3) was calculated by adding the 8 individual FA scores, then dividing this sum by the total number of components answered. Change from baseline was calculated as the value at Week 24 minus the baseline value.
  
  
• Change From Baseline in CRP at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  Blood samples for the determination of CRP were taken at pre-specified visits and were sent to the central laboratory for analysis. Change from Baseline in CRP was calculated as the Week 24 value minus the baseline value. CRP is an acute-phase protein whose plasma concentration increases in response to inflammation. CRP is a useful marker of inflammation.
  
  
• Change From Baseline in ESR at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  ESR is measured by a blood test that shows the rate at which red blood cells sediment in a period of 1 hour. Blood samples for the determination of ESR were taken at pre-specified visits and were measured immediately at the trial site. Change from baseline in ESR was calculated as the Week 24 value minus the baseline value.
  
  
• Change From Baseline in the Short-Form 36 (SF-36v2) Norm-based Scores for Physical Component Summary and Physical Items at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  The SF-36v2 is a standardized questionnaire used to measure overall subjective health status by measuring 8 health-related parameters (each scored from 0 [poorer health] to 100 [better health]): body pain, general mental health (MH), perception of general health, physical functioning, role limitations (RL) caused by mental condition, RL caused by a physical condition, social functioning, and vitality. It yields an 8-scale profile of functional health and well-being scores, as well as psychometrically based physical and MH summary measures and a preference-based health utility index.
  
  
• Change From Baseline in the SF-36v2 Norm-based Scores for Mental Component Summary and Mental Items at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  The SF-36v2 is a standardized questionnaire used to measure overall subjective health status by measuring 8 health-related parameters (each scored from 0 [poorer health] to 100 [better health]): body pain, general mental health (MH), perception of general health, physical functioning, role limitations (RL) caused by mental condition, RL caused by a physical condition, social functioning, and vitality. It yields an 8-scale profile of functional health and well-being scores, as well as psychometrically based physical and MH summary measures and a preference-based health utility index.
  
  
• Change From Baseline in the Functional Assessment of Chronic Illness Therapy (FACIT) Questionnaire Score at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  The FACIT-F score has a valid range of values from 0 to 52, with a higher score indicating a lower burden of fatigue. The subset determining fatigue contains 13 questions. Responses to each question were scored from 0, indicating "Not at all fatigued," to 4, indicating "Very much fatigued."
  
  
• Change From Baseline in Levels of Anti-CCP, RF-IgA, RF-IgG, and RF-IgM at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  The following biomarkers were assessed: Anti-Cyclic Citrullinated Peptide 3 antibody (Anti-CCP), Rheumatoid factor IgA (RF-IgA), RF IgG (RF-IgG), and RF IgM (RF-IgM). Measurements of RF were used to characterize participants' disease activity and immune status. Anti-CCP was used to characterize the disease type and the immune status of the participants. Assessments for which results were below the lower limit of quantification (LLQ) were reported using a value of LLQ/2. Assessments for which results were above the upper limit of quantification (ULQ) were reported using a value of ULQ.
  
  
• Change From Baseline in Levels of IL-6 and Serum Amyloid A at Week 24 [ Time Frame: Baseline and Week 24 ] [ Designated as safety issue: No ]
  The following biomarkers were assessed: Interleukin 6 (IL-6) and Serum Amyloid A. These biomarkers were used to further characterize disease activity.
  
  

This study consists of a Double-blind , placebo controlled, and parallel group part with eligible patients enrolled into a 24 week Double-Blind Period, and randomized in a 1:1 ratio to receive ofatumumab (700mg x 2 infusions) or placebo ( saline x 2 infusions) in addition to their background methotrexate treatment. Patients who completed the 24 week Double-Blind period without receiving rescue DMARD treatment will be eligible to proceed into the 120 week Open-Label Period to receive repeat treatment courses with ofatumumab. In the Open-label Period ofatumumab treatment courses will be given at individualized time intervals only if a clinical response has been achieved following the previous treatment course, and followed by a subsequent worsening in disease activity . Patients who have completed the Open-Label Period or have withdrawn will enter a maximum 2 year Follow-up Period, or until their Bcells return to normal or to baseline levels, whichever occurs earlier.