RT Journal Article
SR Electronic
T1 AMPA Receptor Encephalitis in a Patient With Metastatic Breast Cancer Receiving Palbociclib
JF Neurology - Neuroimmunology Neuroinflammation
JO Neurol Neuroimmunol Neuroinflamm
FD Lippincott Williams & Wilkins
SP e200012
DO 10.1212/NXI.0000000000200012
VO 9
IS 5
A1 Elizabeth Matthews
A1 Barrie Schmitt
A1 Michlene Passeri
A1 Christopher Mizenko
A1 Karen Orjuela
A1 Amanda Piquet
YR 2022
UL http://nn.neurology.org/content/9/5/e200012.abstract
AB Objective To report a case of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor encephalitis (AMPARE) as a potential immune-mediated complication of palbociclib (a cyclin-dependent kinase 4/6 inhibitor).Background Medication-induced autoimmune encephalitis is an increasingly recognized entity. To date, cases have been reported with immune checkpoint inhibitors (ICIs), typically within 3 months and while cancer is responding to immunotherapy.Results A 55-year-old woman with metastatic breast cancer presented with new-onset neurologic symptoms. After diagnosis and treatment in 2008, she was in remission from 2010 to 2021. In April 2021, she developed metastatic recurrence. She started palbociclib in June 2021. PET scan in August 2021 showed improved metastases without new lesions. In September 2021, she developed encephalopathy, vertical nystagmus, and ataxia. Workup revealed AMPA-R antibodies. Palbociclib was stopped, and she received steroids, IVIg, and rituximab with marked improvement in her neurologic symptoms.Discussion AMPARE is a well-described paraneoplastic syndrome. However, it is now understood that paraneoplastic syndromes can be driven by immunomodulatory medications, namely ICIs. Although palbociclib primarily prevents tumor proliferation, emerging data suggest that it may also be immunomodulatory. Given that our patient's AMPARE developed shortly after initiation of palbociclib while her cancer was responding to therapy, we postulate that it may have been unmasked by palbociclib, similarly to what has been reported with ICIs.AIE=autoimmune encephalitis; AMPA-R=α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor; AMPARE=α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor encephalitis; CDK=cyclin-dependent kinase; ICI=immune checkpoint inhibitor; irAE=immune-related adverse event