Emapalumab use in malignancy-associated hemophagocytic lymphohistiocytosis in the United States: the REAL-HLH study.

Malignancy-associated hemophagocytic lymphohistiocytosis (mHLH), a hyperinflammatory syndrome, has poor prognosis and no standard therapy. Emapalumab, a fully human monoclonal antibody that neutralizes the proinflammatory cytokine interferon gamma, is approved for treating primary hemophagocytic lymphohistiocytosis (pHLH). REAL-HLH, a retrospective chart review conducted across 33 US hospitals, evaluated real-world treatment patterns and outcomes in patients treated with ≥1 dose of emapalumab between 20 November 2018 and 31 October 2021. Data are presented for the subset of patients with mHLH. Overall, 51 of 105 (48.6%) patients were categorized as having secondary HLH, of which 17 of 51 patients had HLH associated with an underlying malignancy (mHLH). At HLH diagnosis, the median age (range) was 15.0 (3.0-27.0) years, 6 of 14 (42.9%) patients with available data had a positive Optimized HLH Inflammatory index, indicating pathologic inflammation; 9 of 17 (52.9%) had infections; and 10 of 17 (58.8%) received emapalumab in an intensive care unit. Emapalumab was primarily initiated for treating refractory (10/17; 58.8%) or progressive (3/17, 17.7%) disease. Most patients received HLH-related therapies before (16/17; 94.1%) and/or concurrent with (15/17; 88.2%) emapalumab. Treatment with emapalumab-containing regimens normalized most key laboratory parameters and maintained normal values for others (fibrinogen [11/13; 84.6%], absolute neutrophil count [6/10; 60%], and chemokine ligand 9 [7/8; 87.5%]) per physician assessment. Overall survival at the end of follow-up and 12-month survival probability from emapalumab initiation were 23.5% and 22.1%, respectively. In conclusion, emapalumab-containing regimens normalized, improved, or maintained normal values for most laboratory parameters in patients with mHLH. Future studies are warranted to establish appropriate emapalumab dosing and utility in this high-risk population.

Duke Scholars

Author Jennifer Ann Rothman Pediatrics, Hematology-Oncology