Immune Effector Cell-associated Hemophagocytic Lymphohistiocytosis-like Syndrome (IEC-HS).

Immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome (IEC-HS) is a complication of adoptive cell therapy. Presenting with clinical manifestations of hyperinflammation and surrogate indicators of hyperinflammation such as elevations in serum ferritin and hepatic transaminases, decreasing cell counts, and hypofibrinogenemia, IEC-HS resembles primary and other forms of secondary hemophagocytic lymphohistiocytosis. Nonetheless, this is an iatrogenic complication resulting from the induction of hyperinflammatory pathways during T-cell-mediated anticancer targeting. Distinct from cytokine release syndrome, IEC-associated neurotoxicity syndrome, and IEC-associated hematotoxicity, IEC-HS can be life-threatening. Identification of IEC-HS, optimization of treatment strategies, and use of supportive care are critical to improving outcomes.