AUSTIN, TEX. – Neuromuscular complications from immunotherapy for cancer are rare, but they occur often enough that it is helpful to know which ones can result from different immunotherapies and how to distinguish them from non–adverse event conditions, according to , a neuro-oncologist at Tulane University in New Orleans.
At the annual meeting of the American Association for Neuromuscular and Electrodiagnostic Medicine, Dr. Trevino reviewed immunotherapy types, particularly immune checkpoint inhibitors, and the most common neuromuscular complications – primarily neuropathy, myasthenia gravis (MG), myositis, and encephalitis or meningitis.
“Timing of onset is a critical component to assist in identifying immune checkpoint inhibitor–associated versus non–immune checkpoint inhibitor–associated neuromuscular disease,” Dr. Trevino told attendees. Prompt recognition can be particularly urgent for MG because crisis and death rates are higher when induced by immunotherapy and require quick treatment. “Understanding the mechanisms of action sets a foundation for treatment approach,” he added.
Any part of the nervous system can be affected by immunotherapy toxicity, he said, and syndromes often overlap, with the peripheral nervous system typically more often affected than the central nervous system. Neurologic immune-related adverse events typically occur within four cycles of therapy – about 12 weeks after therapy initiation – but should always involve a work-up to exclude effects from the cancer itself, other neuromuscular diagnoses unrelated to therapy, and other toxicities from chemotherapy.
Recommended first-line treatment is halting immunotherapy with or without corticosteroids, after which most patients improve, often with “rapid, complete resolution of symptoms,” Dr. Trevino said. Restarting immunotherapy treatment is possible in some patients, though.
CAR T-cell and dendritic cell vaccine therapies
Four main types of immunotherapy exist: viral therapy, vaccine therapy, immune checkpoint inhibitors, and adoptive cell transfer, such as chimeric antigen receptor (CAR) T-cell therapy. Dr. Trevino focused on checkpoint inhibitors and adoptive cell transfer.
CAR T-cell therapy is a multistep treatment process that involves first removing blood from the patient to obtain their T cells. These are used to create and grow CAR T cells in the lab so that they can be infused back into the patient. The cells then bind to cancer cells and destroy them. Examples of approved CAR T-cell therapy include Yescarta (axicabtagene ciloleucel) for some types of non-Hodgkin lymphoma and Kymriah (tisagenlecleucel) for acute lymphoblastic leukemia (ALL).
Dendritic cell vaccines are similar to CAR T-cell therapy in that they also use the patient’s own immune cells to create cancer-killing cells that the patient then receives back. The only currently approved dendritic cell vaccine is Provenge (sipuleucel-T) for advanced prostate cancer.
The main toxicity to watch for from CAR T-cell therapy and dendritic cell vaccines is cytokine release syndrome (CRS). It can begin anywhere from 1-14 days after the infusion and involves T-cell expansion in the body that leads to a cytokine storm. Symptoms are wide ranging, including fatigue, fever, loss of appetite, tachycardia, hypotension, pain, rash, diarrhea, headache, confusion, seizures, muscle and joint pain, tachypnea, hypoxia and hallucinations, among others.
Specific central neurotoxicities that can result from CAR T-cell therapy include encephalopathy, cerebral edema, seizures and status epilepticus, cerebral vasospasm, and aphasia.