Tofacitinib as a possible treatment in macrophage activation syndrome: a pilot single-center study in China.

Objectives: Our pilot study investigated the efficacy and safety of tofacitinib (TOF) in patients with macrophage activation syndrome (MAS), providing a new therapeutic option.

Methods: This was a historical comparator, single-center study. Patients enrolled in our study were screened using the 2016 Pediatric Rheumatology International Trials Organization (PRINTO) criteria of MAS. MAS patients deemed suitable for TOF therapy were enrolled in the experimental group. The control group included MAS patients from Yantai Yuhuangding Hospital who had received biological and/or conventional synthetic disease-modifying anti-rheumatic drugs (b/csDMARDs) treatment in a similar period. Clinical characteristics, laboratory test results, MAS treatment response rates, and glucocorticoid discontinuation rates were compared between the two groups before and after treatment. Serious adverse events such as thrombosis or severe infection were recorded.

Results: A total of 36 MAS patients were included-17 in the TOF treatment group and 19 in the b/csDMARDs control group. Baseline demographic and clinical characteristics were comparable between groups. After six weeks, the proportion of febrile patients was significantly lower in the TOF group compared to the control group (11.8% [2/17] vs. 47.3% [9/19], P = 0.021). Significant reductions were also observed in C-reactive protein levels at week 6 (5.9% [1/17] vs. 36.8% [7/19], P = 0.026) and ferritin levels at week 12 (100.0% [17/17] vs. 26.3% [5/19], P = 0.023). The MAS treatment response rate was significantly higher in the TOF group at weeks 2 and 6 (P = 0.029 and P = 0.023, respectively). Glucocorticoid discontinuation was more frequent in the TOF group, with a 12-week discontinuation rate of 100.0% (17/17) compared to 57.9% (11/19) in the control group (P = 0.002). No serious adverse events, including thrombosis or severe infections, were reported.

Conclusion: Our results suggest that TOF may be as effective as or even better than b/csDMARDs, with a quicker and higher response rate in patients with MAS without severe adverse events. Key Points •Tofacitinib may be as effective or better than b/csDMARDs in MAS. •Tofacitinib may act at a quicker and higher response rate in MAS. •Tofacitinib might be an alternative therapeutic option for patients with MAS.