Novel JAK1 Inhibitor Hits the Mark in Arthritis Trial

TOPLINE:

Ivarmacitinib, a novel Janus kinase 1 inhibitor, alleviates symptoms, reduces disease activity, and improves physical function and quality of life in patients with moderate to severe rheumatoid arthritis (RA) who have an inadequate response to conventional synthetic disease-modifying antirheumatic drugs (csDMARDs).

METHODOLOGY:

• This phase 3 trial, conducted across 59 sites in China, evaluated the efficacy and safety of ivarmacitinib in patients with moderate to severe active RA despite treatment with one or more csDMARDs.
• The patients were randomly assigned to receive either placebo (n = 188; mean age, 50.9 years; 85.6% women) or 4 mg ivarmacitinib (n = 189; mean age, 49.7 years; 91% women) or 8 mg ivarmacitinib (n = 189; mean age, 49.8 years; 83.6% women) once daily for 24 weeks, alongside background csDMARDs.
• After 24 weeks, the patients receiving placebo were switched to receive 4 mg ivarmacitinib for the additional 28-week extension period, whereas those receiving ivarmacitinib continued their initial dosage.
• Secondary endpoints included the proportion of patients achieving American College of Rheumatology (ACR) 50/70 responses and, Disease Activity Score 28-joint count C-reactive protein (DAS28(CRP)) score

TAKEAWAY:

• At 24 weeks, the proportion of patients achieving a 20% improvement in the ACR20 response — the primary endpoint — was higher among those receiving 4 mg ivarmacitinib (70.4%) or 8 mg ivarmacitinib (75.1%) than among those receiving placebo (40.4%; P
• The proportion of patients achieving ACR50/70 responses or a DAS28(CRP) score P 
• Compared with the placebo group, both the ivarmacitinib groups showed improvements in patient-reported outcomes such as pain, physical function, quality of life, and duration and severity of morning stiffness.
• The overall rates of treatment discontinuation due to adverse events were low across all the groups, with no deaths, tuberculosis or gastrointestinal perforations reported throughout the 52 weeks.

IN PRACTICE:

“Based on these findings, ivarmacitinib with background csDMARDs allowed, could be considered a treatment option in patients with moderate to severe active RA who have an inadequate response to csDMARDs,” the authors wrote.

SOURCE:

This study was led by Jinjing Liu and Xiaofeng Zeng, Department of Rheumatology and Clinical Immunology, Peking Union Medical College Hospital, Beijing, China. It was published online on November 27, 2024, in Annals of the Rheumatic Diseases.

LIMITATIONS:

As the study was conducted in Chinese population, the findings may have limited applicability across diverse global populations. Additionally, as the placebo-controlled period was limited to 24 weeks due to ethical concerns, comparisons between placebo and ivarmacitinib beyond that period were restricted. Lastly, this study was not powered to compare efficacy and safety between the two active dose regimens.

DISCLOSURES:

This study was funded by Jiangsu Hengrui Pharmaceuticals Co., Ltd. Two authors declared being employees of the company. The other authors reported no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.