Laboratory markers predicting tofacitinib efficacy in Japanese patients with rheumatoid arthritis: A pooled analysis of Phase 2/3 randomised controlled clinical trials.

Objectives: We characterised early changes in laboratory parameters in Japanese patients with rheumatoid arthritis (RA) and assessed whether these changes at Month (M)1 were predictive of tofacitinib efficacy at M3.

Methods: This post hoc analysis included data from Japanese patients with RA receiving tofacitinib or placebo pooled from two Phase (P)2 studies in Japan (NCT00603512; NCT00687193) and one global P3 study (NCT00847613). Outcomes: changes from baseline in laboratory parameters (Week 2 and M1/3); efficacy endpoints (Disease Activity Score in 28 joints, based on C-reactive protein [DAS28-4(CRP)], DAS28-4, based on erythrocyte sedimentation rate [DAS28-4(ESR)], and American College of Rheumatology-N index) at M3. Univariate/multivariable analyses assessed whether changes in laboratory parameters at M1 were predictive of efficacy outcomes at M3.

Results: Overall, 467 patients receiving tofacitinib and 104 receiving placebo were included. Tofacitinib treatment was associated with decreases from baseline in CRP, ESR, neutrophils, and platelets, and increases in lymphocytes, haemoglobin, and lipids up to M3. Decreased platelet count and increased low-density lipoprotein cholesterol and haemoglobin at M1 were predictive of changes in efficacy outcomes at M3.

Conclusions: Changes in laboratory parameters at M1 could potentially be used to assess whether tofacitinib therapy will be effective at M3; further investigation is needed.