CAR-T-cell-related hemophagocytic lymphohistiocytosis (HLH)/ MAS:
• Profound systemic inflammatory state characterized by cytotoxic T cell hyperactivation (IFNγ) → macrophages (IL-6), lymphohistiocytic tissue infiltration, and multiorgan failure; develops in ~1% of patients treated with CAR‐T.
• Definition (proposed): Patient with peak ferritin >10,000 during CRS phase (typically <D5), and two of the following: grade ≥3 organ toxicities involving the liver, kidney, lung; or hemophagocytosis in bone marrow or other organs.
• Signs/symptoms: Fever, cytopenias (2/3 lines); signs and symptoms related to multiorgan dysfunction
• Diagnosis: laboratory findings resemble HLH; CBC diff (cytopenia), ferritin (>10,000), sIL2R, LDH, fibrinogen, triglycerides, AST/ALT, Bili, Cr; BMBx rarely critical (low sensitivity, low specificity).
• Therapy: High mortality, do not delay diagnosis, escalate therapy aggressively (interdisciplinary approach)
- Manage with anti-IL-6 (tocilizumab) and high-dose glucocorticoids; commonly necessitates additional therapy
- If failure to improve in 48h, consider etoposide as in HLH-94 treatment protocol; consider intrathecal cytarabine
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