Ruxolitinib for secondary hemophagocytic lymphohistiocytosis: First case report.

Hemophagocytic lymphohistiocytosis (HLH) is an immune-mediated disorder resulting in hyper-activation of inflammatory cytokines. If left untreated, the uncontrolled inflammatory response can lead to significant tissue injury and potentially life-threatening multi-organ dysfunction. Conventional immunosuppressive agents are available for the management of HLH, including dexamethasone, cyclosporine, and etoposide; however, patients may not respond to these therapies. Clinicians may turn toward alternative pharmacologic agents that likely have less clinical evidence. We describe a case of secondary HLH that did not respond favorably to conventional treatments. Serum inflammatory markers continued to rise significantly with clinical deterioration and worsening pancytopenia. The severe thrombocytopenia and neutropenia were deemed to have contributed to a spontaneous subdural hematoma and candidemia, respectively. Ruxolitinib, a Janus kinase (JAK) 1/2 inhibitor, was then utilized as a novel salvage therapy based on available in vivo murine data at the time. Following initiation, there was improvement seen in several disease markers, including serum ferritin, lactate dehydrogenase, fibrinogen, and liver function tests. However, the pancytopenia did not show signs of recovery. The patient ultimately expired after 7days of ruxolitinib treatment. It is unclear if the improvement in disease markers was attributed to JAK inhibition alone. However, this experience combined with the positive in vivo murine data suggests that ruxolitinib may serve as a potential treatment option for HLH, pending the release of more robust data. To our knowledge, this is the first human case report describing the use of ruxolitinib for HLH. Future studies are warranted to determine the role of ruxolitinib in this setting.