Management of Immune Effector Cell-Associated HLH-Like Syndrome

Diagnostic Considerations

The American Society of Clinical Oncology recommends that HLH associated with immune effector cell therapy presents with clinical features similar to classic HLH but requires specific diagnostic criteria including elevated ferritin plus at least two organ toxicities 2
Diagnostic workup should include assessment for fever, hepatosplenomegaly, and cytopenias in patients with suspected immune effector cell-associated HLH-like syndrome 3
Evidence of hemophagocytosis in bone marrow or organs is a key diagnostic criterion for HLH, according to the American Society of Hematology 2
Organ dysfunction including transaminitis, renal insufficiency, or pulmonary edema is a common feature of immune effector cell-associated HLH-like syndrome 1

The American College of Physicians recommends high-dose corticosteroids as the mainstay of initial treatment for immune effector cell-associated HLH-like syndrome, with methylprednisolone 1g/day for 3-5 consecutive days as the recommended starting approach 1
The American Society of Hematology suggests monitoring ferritin, sCD25, cell counts, and clinical response every 12 hours to guide therapy in patients with immune effector cell-associated HLH-like syndrome 6
For patients not responding adequately to corticosteroids within 24-48 hours, the National Comprehensive Cancer Network recommends adding cyclosporine A or IL-1 receptor antagonist (anakinra) to the treatment regimen 7
The European Society for Medical Oncology suggests considering tocilizumab (anti-IL-6) for cases without significant neurologic involvement, and rituximab (375 mg/m² weekly for 2-4 doses) for cases with EBV trigger 8

The American Society of Clinical Oncology recommends using tocilizumab cautiously when concurrent ICANS (Immune Effector Cell-Associated Neurotoxicity Syndrome) is present, as it may worsen neurologic symptoms 2
If infection is identified as a trigger, the Infectious Diseases Society of America recommends initiating appropriate antimicrobial therapy alongside immunosuppressive treatment 3
The American Society of Hematology suggests that supportive care is critical and includes management of cytopenias (transfusion support) and vasopressor support for hypotension in patients with immune effector cell-associated HLH-like syndrome 7

The American College of Physicians recommends frequent reassessment (at least every 12 hours) of clinical status and laboratory parameters to assess treatment response in patients with immune effector cell-associated HLH-like syndrome 4
The American Society of Hematology suggests monitoring ferritin, sCD25, complete blood counts, liver function, and renal function to assess treatment response 6
Improvement in organ dysfunction and decreasing inflammatory markers indicate treatment success, according to the American Society of Clinical Oncology 1

The American Society of Hematology recommends investigating several novel approaches in clinical trials, including JAK inhibitors (ruxolitinib) and anti-IFN-γ monoclonal antibody (emapalumab) for the treatment of immune effector cell-associated HLH-like syndrome 8

The American Society of Clinical Oncology warns that delayed recognition and treatment of immune effector cell-associated HLH significantly increases mortality 1
Distinguishing between CRS (cytokine release syndrome) and HLH can be challenging as they share clinical features, according to the American Society of Hematology 2
The National Comprehensive Cancer Network recommends avoiding immunosuppression in cases where infection is the primary driver until appropriate antimicrobial therapy is initiated 3