Treatment‐Emergent Parkinsonism in Four Patients Treated with Chimeric Antigen Receptor T‐Cell Therapy

Background Treatment‐emergent motor and neurocognitive adverse events (MNTs) are rare but increasingly well‐documented complications of chimeric antigen receptor T‐cell (CAR‐T) therapy. Here, we describe the development of parkinsonism in four patients who received CAR‐T therapy with either B‐cell maturation antigen (BCMA)‐targeting ciltacabtagene autoleucel for multiple myeloma (n = 3) or CD‐19‐targeting axicabtagene autoleucel for lymphoma (n = 1). Cases We report four cases of parkinsonism in patients who received CAR‐T therapy. Two patients had evidence of underlying neurodegenerative parkinsonism, either clinically or through subsequent workup for their movement disorder. All patients received some combination of symptom‐directed and immunomodulatory therapies. Conclusion This report describes features of CAR‐T treatment‐emergent parkinsonism, introduces parkinsonism as a potential effect of CD‐19‐targeted CAR‐T therapy, and suggests utility of screening for underlying clinical or biomarker signs of pre‐existing neurodegenerative parkinsonism prior to CAR‐T infusion.