Safety and Effectiveness of Baricitinib in Chinese Patients with Moderate-to-Severe Rheumatoid Arthritis: 24-Week Results from a Post-Marketing Safety Study

Introduction Baricitinib, a JAK1/JAK2 inhibitor, is approved for treatment of moderate-to-severe rheumatoid arthritis (RA) in China. This single-arm, prospective, multi-center, post-marketing safety study (PMSS) evaluated the safety and effectiveness of baricitinib in Chinese patients. Methods This study included adult patients with moderate-to-severe active RA who received baricitinib over periods of approximately 12 and 24 weeks. The primary endpoint was safety, defined as week 12 adverse event (AE)/serious AE incidence. Secondary endpoints were week 24 safety and effectiveness (disease activity score with 28 joints/C-reactive protein [DAS28-CRP] and simplified/Clinical Disease Activity Index [SDAI/CDAI]). Results Safety analyses included 667 patients (female, 82.3%; mean age, 53.3 years; mean RA duration, 86.9 months); 106/667 (15.9%) were 65–74 years old and 19/667 (2.8%) were ≥ 75 years old; 87.0% received baricitinib 2 mg QD. Total exposure was 262.1 patient-years (PY). At week 12, AEs had occurred in 214 (32.1%; exposure-adjusted incidence rate [EAIR], 172.5 per 100 PY) patients (serious AEs: 22 [3.3%; EAIR, 15.0]). At week 24, AEs had occurred in 250 (37.5%; EAIR, 125.9) patients (serious AEs: 28 [4.2%; EAIR, 10.9]). Two patients (0.3%) died (of pneumonia and unknown cause); EAIR for death, 0.77. Serious infection occurred in 1.2% of patients (EAIR, 3.1). Hepatotoxicity occurred in 3.4% of patients (EAIR, 9.0). No patients met potential Hy’s law laboratory criteria (alanine/aspartate aminotransferases ≥ 3 × upper limit of normal (ULN) and total bilirubin ≥ 2 × ULN). Malignancy occurred in one patient. No patients experienced venous thromboembolism (VTE) or major adverse cardiovascular events (MACE). At week 24, 52.4%, 27.5%, and 27.6% of patients achieved remission per DAS28-CRP, SDAI, and CDAI, respectively. Conclusions This PMSS investigated the safety and effectiveness of baricitinib in clinical practice in China. No VTE/MACE or new safety signals were reported and there was promising effectiveness, supporting the use of baricitinib in Chinese patients with moderate-to-severe active RA. Trial Registration EU PAS Register: EUPAS34213.