Abstract Pembrolizumab is an immune checkpoint inhibitor (ICI) used to treat multiple cancers. 30-60 percent of patients using ICI may experience an immune related adverse event (irAE). Encephalopathy and status epilepticus are rare irAEs, and in this case we describe a patient who acquired these syndromes in the setting of pembrolizumab use. The patient is a 79-year-old female with a medical history of schizoaffective disorder, expressive aphasia, and metastatic squamous cell carcinoma of the right facial region who presented to our hospital for weakness, lethargy, and confusion. Two months prior to admission, the patient completed radiation and was started on pembrolizumab, carboplatin, 5-fluorouracil chemotherapy one month prior for her squamous cell carcinoma lesion. During the initial encounter, she was only oriented to self, she was easily arousable, and her speech was slow. Exam revealed right sided gaze preference. MRI of the brain revealed gyriform restricted diffusion in the right frontal lobe which the radiologist suggested may reflect sequelae of status epilepticus. EEG showed lateralized periodic discharges in the right hemisphere which may be seen as an ictal phenomenon, and at minimum represented a significant focus of cortical irritability. The patient received loading doses of levetiracetam and phenytoin, and he was started on a regimen of 1500 mg IV levetiracetam daily. On hospital day four, the patient was transferred to the intensive care unit for increased somnolence and confusion. Labs revealed worsening respiratory acidosis, and she was subsequently intubated for hypercapnic and hypoxic respiratory failure. Continuous EEG confirmed initial concerns of status epilepticus. Repeat routine EEGs continued to show possible focal seizures and diffuse slowing despite increasing the antiepileptic regimen to levetiracetam, phenytoin, valproic acid, and clobazam. Due to refractory status epilepticus autoimmune involvement was considered, and she received IVIG and 1 g IV methylprednisolone over 5 days. Unfortunately, the patient never recovered throughout her clinical course. She repeatedly failed spontaneous awakening trials and spontaneous breathing trials. Considerations for tracheostomy placement were ongoing; however, the patient was unrepresented. Discussions with the social worker, caregiver, chaplain, and hospital ethics committee were held and it was decided that the patient would undergo compassionate terminal extubation. Pembrolizumab received approval for head and neck squamous cell carcinoma in 2019. Since then, it has been approved for 19 additional cancers. As it continues to show utility, and likely be approved for additional cancer treatments, it is important that providers are vigilant for ICI associated with irAEs. This abstract is funded by: None
Thota et al. (Fri,) studied this question.