Tanaka Y, Takeuchi T, Tanaka S, et al. - In a double-blind phase III study, patients with RA and incompetent response to former disease-modifying anti-rheumatic drugs (DMARDs) were randomized to peficitinib (an oral Janus kinase inhibitor) 100 mg once daily, peficitinib 150 mg once daily, placebo or open-label etanercept for 52 weeks’ treatment in order to examine the efficiency and safety of peficitinib, in patients (n = 507) with RA. At week 12/early termination (ET), American College of Rheumatology (ACR)20 response rates were significantly higher in the peficitinib 100 mg and 150 mg groups vs placebo. For both peficitinib doses vs placebo, ACR50/70 response rates were also higher. Betterments in ACR response were sustained until week 52. For both peficitinib doses vs placebo, at week 12/ET, variations from baseline in disease activity score 28-CRP/ESR and the ACR core set were significantly greater. Across treatment arms, adverse event incidence was comparable. Incidence of serious infection and herpes zoster-related disease was greater with peficitinib compared with placebo, though with no apparent dose-dependent rise. Thus, peficitinib 100 mg once daily or 150 mg once daily was effective in decreasing RA symptoms and was well tolerated in comparison with placebo in individuals with RA and incomplete response to DMARDs.