Systemic juvenile idiopathic arthritis (sJIA) is a severe form of arthritis in children that can lead to serious complications like macrophage activation syndrome (MAS) and lung disease. Even with current treatments like steroids and IL-1 inhibitors, some patients still suffer from these complications. Researchers are now looking at a drug called ruxolitinib, which targets specific inflammation pathways, to see if it can help control the disease better.

Researchers reviewed the medical records of three children with sJIA or similar conditions who were treated with ruxolitinib. The goal was to see if the drug could improve their condition and reduce their need for other treatments like steroids.

The study involved three patients aged 5 to 15, two girls and one boy:

1. Patient A: This patient had repeated episodes of MAS, which caused severe symptoms like fever and low blood pressure. After starting ruxolitinib along with other medications, the patient’s condition improved significantly, and they were able to stop other drugs while continuing ruxolitinib alone. The patient has remained stable for 10 months without any further MAS flares.
2. Patient B: This patient had sJIA and developed severe MAS triggered by an Epstein-Barr virus (EBV) infection. Initial treatments helped stabilize the condition, but adding ruxolitinib provided further improvement. This allowed the patient to reduce and eventually stop taking steroids within 9 weeks. Ruxolitinib was stopped after 3 months, and the patient continued on another medication.
3. Patient C: This patient developed lung disease associated with sJIA while on another medication. Adding ruxolitinib improved joint pain and lung function within 4 to 6 weeks. The patient’s steroid dose was reduced by 50% as their condition improved.

Throughout the study, patients did not experience serious side effects like infections or significant changes in blood cell counts. One patient had a mild increase in cholesterol. The average follow-up time was about 214 days, and patients were on ruxolitinib for an average of 189 days.

Ruxolitinib was well tolerated by these patients with sJIA, showing no major side effects. It helped improve disease control, either on its own or with other medications, and allowed for a reduction in steroid use. This suggests that ruxolitinib could be a valuable addition to the treatment options for sJIA and MAS, with the potential for higher doses if needed.