Anti-Hu-Associated Autoimmune Limbic Encephalitis in a Patient with PD-1 Inhibitor-Responsive Myxoid Chondrosarcoma

Area of Science:

• Neurology
• Oncology
• Immunology

Background:

• Immune checkpoint inhibitors (ICIs) like anti-PD1 therapy are increasingly used for cancer treatment.
• Autoimmune encephalitis is an uncommon but serious neurological adverse event associated with ICI therapy.
• Anti-Hu antibodies are associated with paraneoplastic neurological syndromes, particularly in small cell lung cancer.

Observation:

• A patient with myxoid chondrosarcoma and pre-existing anti-Hu antibodies developed autoimmune limbic encephalitis within 8 weeks of anti-PD1 therapy.
• Neurologic decline was rapid and fatal despite initial response to immunosuppression.
• Tumor reduction was observed with anti-PD1 therapy.

Findings:

• This case demonstrates a fatal outcome of anti-Hu-associated autoimmune limbic encephalitis following anti-PD1 therapy.
• The patient's pre-existing anti-Hu antibodies may have predisposed them to this severe neurological complication.
• Rapid progression of neurological symptoms occurred despite immunosuppressive treatment.

Implications:

• Increased use of ICIs necessitates heightened awareness and prompt management of neurological adverse events.
• Pharmacovigilance is crucial for identifying and mitigating risks associated with ICI therapy, especially in patients with onconeuronal antibodies.
• Understanding the interplay between ICIs, pre-existing autoimmunity, and cancer is vital for improving patient outcomes.