A case report of the diagnosis and treatment of immune checkpoint inhibitor-related encephalitis induced by camrelizumab.

Background: Camrelizumab has been widely used in the treatment of various cancers, it is important to determine the side-effect of this drug and the corresponding treatment strategy.

Case description: The current case report describes the clinic, diagnosis, treatment and prognosis of camrelizumab-related encephalitis. Camrelizumab was administrated to a 67-year-old man with squamous cell carcinoma (SCC), a form of non-small cell lung cancer (NSCLC). One month after the treatment, the patient showed typical encephalitis symptoms including systemic fatigue, numbness of extremities and walking instability. Furthermore, the total protein in cerebrospinal fluid (CSF) was significantly elevated (1,399 vs. normal range 120-600 mg/L). Importantly, magnetic resonance imaging showed there was no brain metastasis. The patient did not get better after two days of intravenous injection of thioctic acid (1.2 g) and cobamamide (1.5 mg) once daily. Therefore, this patient was diagnosed as camrelizumab-related encephalitis. Then, we put him on one-month regimen: oral taper corticoids (methylprednisolone, MP) at 500 mg (days 1-4), 120 mg (days 5-10) and 60 mg (days 11-15); MP was replaced with oral prednisone acetate at 30 mg (days 16-30). After the treatment, the total protein in CSF was decreased to 873 mg/L, and all of encephalitis-related symptom was completely lost. About one year after the onset of encephalitis, the patient showed no recurrence of neurological symptoms.

Conclusions: The present case proves the efficacy and safety of corticoids in the treatment of camrelizumab-related adverse effects.