Baricitinib for relapsing giant cell arteritis: a prospective open-label 52-week pilot study.

BACKGROUND/PURPOSE: Preclinical vascular inflammation models have demonstrated effective suppression of arterial wall lesional T cells through inhibition of Janus kinase 3 and JAK1. However, JAK inhibition in patients with giant cell arteritis (GCA) has not been prospectively investigated. METHODS: We performed a prospective, open-label, pilot study of baricitinib (4 mg/day) with a tiered glucocorticoid (GC) entry and accelerated taper in patients with relapsing GCA. RESULTS: 15 patients were enrolled (11, 73% female) with a mean age at entry of 72.4 (SD 7.2) years, median duration of GCA of 9 (IQR 7-21) months and median of 1 (1-2) prior relapse. Four (27%) patients entered the study on prednisone 30 mg/day, 6 (40%) at 20 mg/day and 5 (33%) at 10 mg/day. Fourteen patients completed 52 weeks of baricitinib. At week 52, 14/15 (93%) patients had ≥1 adverse event (AE) with the most frequent events, including infection not requiring antibiotics (n=8), infection requiring antibiotics (n=5), nausea (n=6), leg swelling (n=2), fatigue (n=2) and diarrhoea (n=1). One subject required baricitinib discontinuation due to AE. One serious adverse event was recorded. Only 1 of 14 (7%) patients relapsed during the study. The remaining 13 patients achieved steroid discontinuation and remained in disease remission during the 52-week study duration. CONCLUSION: In this proof-of-concept study, baricitinib at 4 mg/day was well tolerated and discontinuation of GC was allowed in most patients with relapsing GCA. Larger randomised clinical trials are needed to determine the utility of JAK inhibition in GCA. TRIAL REGISTRATION NUMBER: NCT03026504.

Immune checkpoint inhibitor-induced inflammatory arthritis: a novel clinical entity with striking similarities to seronegative rheumatoid arthritis.

OBJECTIVE: To determine the clinical and serologic similarities and differences between inflammatory arthritis induced by immune checkpoint inhibitors (IA-irAE) and rheumatoid arthritis (RA). METHODS: In this retrospective cross-sectional comparative study, 20 patients with IA-irAE were age and sex matched to 40 seropositive and 40 seronegative RA patients. Electronic medical records were reviewed from diagnosis of inflammatory arthritis through May 2019. Arthritis characteristics, treatment, and relevant laboratory and serologic studies were captured. RESULTS: Clinically, IA-irAE differed from seropositive and seronegative RA with respect to disease duration (4.18 versus 11.59 and 13.3 months, respectively, p = 0.005 (IA-irAE vs seropositive RA), p = 0.002 (IA-irAE vs seronegative RA)), polyarticular joint involvement at presentation (75% versus 97.5% and 100%, p = 0.013, p = 0.003), absence of erosive changes (5.9% vs 43.6% and 53.8%, p = 0.005, p = 0.001), mean prednisone dose (24.7 mg versus 16.53 mg and 15.68 mg, p = 0.008, p = 0.005), and use of methotrexate (5.0% versus 85.0% and 70.0%, p < 0.0001, p < 0.0001). Serologically, IA-irAE closely resembled seronegative RA. ANA positivity was seen in a minority of patients and did not differ significantly between all groups; however, the ANA staining pattern (speckled) was similar between IA-irAE and seronegative RA (100% versus 75%, respectively) and was not commonly observed in seropositive RA (18.2%). CONCLUSION: IA-irAE is a new subset of IA that resembles seronegative RA immunologically. Our findings suggest that further study of IA-irAE might provide a window into underlying pathogenic mechanisms of early-stage seronegative RA. Key Points • Comprehensive comparison of clinical features between inflammatory arthritis irAE (IA-irAE) and regular rheumatoid arthritis indicates IA-irAE as a new subset of inflammatory arthritis. • IA-irAE resembles seronegative RA immunologically, suggesting that study of IA-irAE may provide a window into underlying pathogenic mechanisms of early-stage seronegative RA.