Immune checkpoint inhibitor induced autoimmune encephalitis in a patient with metastatic melanoma

Abstract

Background: Immune checkpoint inhibitors have changed the therapeutic milieu for patients with metastatic melanoma. However, their use may promote autoimmunity in virtually any organ in the body due to the blockade of intrinsic immune down regulators such as cytotoxic T-lymphocyte antigen- 4 (CTLA-4), programmed cell death 1 (PD1) or its ligand (PDL1). Immune mediated adverse neurological events are rare with these agents, however, and are seen in < 1% of treated patients. We report a patient with immune checkpoint inhibitor associated autoimmune encephalitis, with complete clinical recovery after treatment.
Case Report: A 49-year-old female with metastatic melanoma currently on nivolumab therapy but recently on ipilimumab/nivolumab combined therapy presented with a new headache. She also reported associated confusion, loss of balance, personality changes and language difficulty. Magnetic resonance imaging of the brain did not reveal any evidence of metastasis, infarct, meningitis, or encephalitis. Lumbar puncture revealed an elevated protein level and pleocytosis, with a normal glucose level. She was started on empiric glucocorticoid therapy with a presumptive diagnosis of immune checkpoint inhibitor associated autoimmune encephalitis. She improved considerably by day 3 of treatment with complete resolution of neurological symptoms by day 5.
Conclusion: Immune checkpoint inhibitors are increasingly important in cancer immunotherapy as they can cause sustained remissions in patients with metastatic melanoma and other malignancies. Because these drugs block immune-regulatory targets, they can lead to enhanced activation of immune system resulting in immune-related adverse events. Autoimmune encephalitis is a rare immune-related adverse event associated with immune checkpoint inhibitors. The incidence of autoimmune encephalitis is higher with combination or sequential CTLA-4 (ipilimumab) and PD1(nivolumab) inhibitor therapy than with monotherapy. With more widespread use of immunotherapy, it is important for clinicians to be aware of this rare and reversible cause of encephalitis. Early recognition and prompt initiation of immunosuppressive therapy with glucocorticoids is essential to enhance neurological recovery.