Retrospective analysis of ruxolitinib as induction treatment in pediatric hemophagocytic lymphohistiocytosis

<b>Purpose:</b> To retrospectively evaluate the efficacy and safety of ruxolitinib, with or without intensive chemotherapy, in pediatric patients with hemophagocytic syndrome.<b>Methods:</b> Pediatric patients with newly diagnosed hemophagocytic lymphohistiocytosis treated with ruxolitinib between January 2021 and December 2024 were analyzed.<b>Results:</b> A total of 34 patients were included, with a median age of 45.6 months. The median ruxolitinib treatment duration was 62 days, with a median daily dosage of 0.63 mg/kg. Twenty-four patients received VP-16, while ten did not. Significant differences were observed in hemoglobin, sCD25, LDH, and ALT levels between the groups. The overall response rates at weeks 2, 4, and 8 were 73.5%, 76.4%, and 70.6% respectively. Platelets, ferritin, triglycerides, IL-6, IL-10, TNF-α, and liver function markers also changed significantly. The median follow-up was 502 days. Seven patients died, with a two-year overall survival rate of 78.3%, higher in the non-VP-16 group (90.0%) than the VP-16 group (73.2%). The two-year event-free survival rate was 63.2%, with 80.0% in the non-VP-16 group and 58.3% in the VP-16 group. Poor prognostic factors included high IL-6 levels, lack of response to initial ruxolitinib, and bone marrow hemophagocytic cells. The VP-16 dosage was reduced compared to HLH-1994, and no patients discontinued ruxolitinib due to side effects.<b>Conclusion:</b> Ruxolitinib is effective and safe for pediatric hemophagocytic syndrome, potentially reducing the need for etoposide. Its initial treatment response can serve as an important factor for prognostic analysis.