S5602 Tocilizumab-Induced Multiorgan Failure Following Rapid Infusion: A Case of Acute Liver Failure and Bowel Pneumatosis

Introduction: Tocilizumab, an interleukin-6 (Il-6) receptor inhibitor, is used to treat a variety of rheumatologic conditions including rheumatoid arthritis (RA). It is typically administered via intravenous infusion over 60 minutes; faster infusion is discouraged due to risk of hypersensitivity reactions. Though uncommon, serious gastrointestinal (GI) complications such as bowel ischemia, pneumatosis, and perforation have been reported. We present a case of multiorgan failure with gastrointestinal and hepatic involvement following rapid tocilizumab infusion in a patient with underlying primary biliary cholangitis (PBC). Case Description/Methods: A 62-year-old woman with RA and cirrhosis from PBC presented with progressive bilateral lower extremity weakness, diarrhea, and falls. She had been receiving monthly tocilizumab infusions but, 4 days prior to presentation, received her usual dose over 20 minutes instead of the recommended 60. Baseline liver function and international normalized ratio (INR) were normal. On admission, she was found to have aspartate aminotransferase 846 U/L, alanine aminotransferase 273 U/L, bilirubin 9.3 mg/dL, and INR 1.5. Her condition worsened with progressive encephalopathy, hyperbilirubinemia (peak 10.6 mg/dL), worsening transaminases, and INR peaked to 3.5. Computed tomography (CT) imaging revealed extensive bowel pneumatosis, but no perforation. Eventually the patient developed hypoxic respiratory failure, renal failure, and shock requiring intensive care unit level care. Discussion: GI manifestations in this case were prominent and may have been mediated by tocilizumab impairing gut barrier function through Il-6 inhibition. Il-6 promotes vascular endothelial growth factor (VEGF) signaling to maintain mucosal blood flow and epithelial repair via nitric oxide and prostaglandin production; thus, its inhibition may impair intestinal perfusion and increase the risk of ischemia. This is a rare case suggesting that rapid infusion may amplify endothelial dysfunction that eventually led to bowel pneumatosis, acute liver failure, and subsequently multiorgan failure. While faster infusion protocols have been deemed safe in select populations without significant comorbidities, their safety in patients with cirrhosis remains uncertain. Hence the patient's underlying cirrhosis likely increased her susceptibility to ischemic gut injury and hepatic decompensation. This case highlights the need for caution and prompt recognition of early organ injury in high-risk patients receiving tocilizumab, particularly in the context of rapid infusion.