Biomarker Changes in Response to Tofacitinib Treatment in Patients With Polyarticular-Course Juvenile Idiopathic Arthritis

Objective: We examine levels of candidate blood-based biomarkers (CBBs) in patients with juvenile idiopathic arthritis (JIA) treated with tofacitinib.

Methods: Patients with JIA who participated in clinical trial NCT02592434 received tofacitinib from baseline to week 18. Serial serum samples were assayed for CBBs (S100A8/9, S100A12, interleukin-18 [IL-18], serum amyloid A, resistin, vascular endothelial growth factor, angiopoietin-1, angiopoietin-2, matrix metalloproteinase 8 [MMP8], MMP2, tissue inhibitor of metalloproteinases 1, leptin, chemokine [C-X-C motif] ligand 9, soluble IL-2 receptor, intercellular adhesion molecule 1, soluble tumor necrosis factor receptor, IL-6, IL-23, monocyte chemotactic protein 1, chemokine [C-C motif] ligand 18 [CCL18], and CCL20). Association of CBBs with JIA response to treatment from baseline to week 18 were assessed.

Results: This study included 166 patients with polyarticular-course JIA. Paired serum samples from 143 patients were available at both baseline and week 18. Thirty-five percent (50 of 143) of patients had a JIA-American College of Rheumatology 90 (JIA-ACR90) level improvement, whereas 90, 121, and 137 (63%, 85%, and 96%) achieved JIA-ACR70, 50, and 30 improvement at week 18. Despite small numerical differences by JIA category, there were no baseline CBB values that independently predicted a decrease in Juvenile Arthritis Disease Activity Score (JADAS-27) or JIA-ACR90 response by week 18. Decrease in resistin level (baseline to week 18) was significantly associated with week 18 improvement in JADAS-27 and JIA-ACR90 response after adjusting for age, sex, JIA disease duration, and baseline resistin (r² 0.79, SE 0.070, P < 0.01, and odds ratio [95% confidence interval] 1.134 [1.018-1.264]). HLA-B27 positivity was significantly associated with not achieving a JIA-ACR90 response at week 18 (P = 0.0097).

Conclusion: Among the CBBs included, only resistin was significantly associated with treatment response, and no CBB was identified that forecasts JIA improvement after initiation of tofacitinib. The association of HLA-B27 positivity with lower response to tofacitinib in JIA is intriguing and merits further study.