PD-1 blockader-associated atypical hemophagocytic lymphohistiocytosis: A cautionary case report

Hemophagocytic lymphohistiocytosis (HLH) is a fatal immune hyperactivity syndrome with high mortality. It seriously endangers human health. HLH associated with immune checkpoint inhibitors is rare, and no particular diagnostic guidelines or treatment regimens exist. A 36-year-old patient with metastatic right atrial angiosarcoma was treated with programmed cell death-1 (PD-1) blockader toripalimab and pazopanib, a vascular endothelial growth factor receptor blockader. However, the patient presented to our center with HLH, and he accepted combination therapy of therapeutic plasma exchange (TPE) and immunotherapy. The patient improved quickly, after only one TPE procedure. Finally, he was discharged after completing two TPE procedures. We summarize a case of PD-1 blocker associated atypical HLH that was successfully treated with TPE. Further evidence is needed to elucidate whether TPE has therapeutic potential for immunotherapy associated HLH.