A Study for Japanese Participants With Rheumatoid Arthritis (RA)

The following parameters are reported for the first SC injection of tabalumab: AUC(0-tlast) defined as AUC from time 0 to time t, where t is the time at the end of the dosing interval; AUC(0-2W) defined as AUC from time 0 to Week 2; and AUC(0-tau) defined as AUC during 1 dosing interval at steady state.

Cmax for the first SC injection of tabalumab is reported.

B-lymphocyte antigen, CD20+, is an activated-glycosylated phosphoprotein expressed on the surface of all mature B cells. Percent change from baseline in B cell counts=[(post-baseline CD20+ B cell count-baseline CD20+ B cell count)/(baseline CD20+ B cell count)]*100. A negative change indicates a decrease in cell count.

During the analysis of anti-CCP, the analytical method was changed from the Inova ELISA method to the Roche Cobas 6000 method due to the discontinuation of a reagent used in the Inova ELISA method. The anti-CCP data are summarized separately for samples collected before and after the method change. No post-baseline samples from the 120 mg tabalumab Q4W and Q2W cohorts were analyzed using the Inova ELISA method. For both methods, a decrease in anti-CCP antibodies indicated an improvement in the participant's condition.

During the analysis of anti-CCP, the analytical method was changed from the Inova ELISA method to the Roche Cobas 6000 method due to the discontinuation of a reagent used in the Inova ELISA method. The anti-CCP data are summarized separately for samples collected before and after the method change. No baseline samples from the 30 mg, 60 mg, and 120 mg tabalumab Q4W cohorts were analyzed using the Roche Cobas 6000 method. For both methods, a decrease in anti-CCP antibodies indicated an improvement in the participant's condition.

RF is an autoantibody (antibody directed against an organism's own tissues) most relevant in rheumatoid arthritis (RA). Higher RF levels indicate an aggressive RA and a higher risk of joint damage. A decrease in RF levels indicate an improvement in the participant's condition.

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 M (IgM), and immunoglobulin A (IgA) levels are reported. A negative change indicates a decrease in immunoglobulin levels.

CRP is an indicator of inflammation. The percent change from baseline in CRP=[(post-baseline CRP- baseline CRP)/(baseline CRP)]*100. A negative change indicates an improvement in the participant's condition.

ESR is a laboratory test that provides a non-specific measure of inflammation. The test assesses the rate at which red blood cells fall in a test tube. Reference ranges are gender-specific and can vary slightly among laboratories. The normal range is approximately ≤10 millimeters per hour (mm/h) for males and ≤20 mm/h for females. Higher scores indicate greater inflammation. The percent change from baseline in ESR=[(post-baseline ESR- baseline ESR)/(baseline ESR)]*100. A decrease in ESR indicates an improvement in the participant's condition.