To investigate the efficacy and safety of the Janus kinase inhibitor ruxolitinib in the treatment of recurrent or refractory hemophagocytic lymphohistiocytosis (HLH) in children. We performed a retrospective analysis of ruxolitinib in children with recurrent or refractory HLH in Beijing Children's Hospital. All patients were treated firstly with HLH-94 protocol. Patients received oral ruxolitinib on a continuous 28-day cycle or until disease progression or unacceptable toxicity. The median age of enrolled patients was 1.7 years (range 9 months-5.0 years). The median time from the beginning of first-line treatment to the initiation of ruxolitinib was 3 (2-6) weeks. The median follow-up time was 14 months (1 week-24 months). Five children were diagnosed with EBV-related HLH, two with familial HLH, one with autoinflammatory disease-related HLH, and the other with unclear etiology. After the first-line treatment, seven patients had no remission (NR). The other two patients relapsed within 2-4 weeks after complete remission (CR). After oral administration of ruxolitinib, all patients' body temperatures decreased to the normal range within 48 h. At 1 week of receiving ruxolitinib, three patients (33.3%) achieved partial remission (PR). Five patients (55.6%) improved but did not achieve PR. One patient (11.1%) died. Compared with other causes of HLH, children with refractory or recurrent EBV-HLH had a poor response to ruxolitinib alone (Fisher's exact test, P = 0.048). Until the last follow-up, the three patients who achieved CR survived without recurrence. For children with recurrent or refractory HLH, ruxolitinib is a tolerable salvage therapy. Although some children could not achieve CR after one week of treatment, combination with chemotherapy could gain time for further treatment or bone marrow transplantation.
Keywords: Hemophagocytic lymphohistiocytosis; JAK-STAT pathway; Ruxolitinib; Treatment.