A rare neurological adverse event of palbociclib: a chronic inflammatory demyelinating polyneuropathy (CIDP) mimic
Year: 2026
Type: article
Study design: Case Report
Abstract: PURPOSE: Hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) breast cancer accounts for approximately 65-70% of all breast cancer cases. First-line treatment for metastatic HR+/HER2- disease typically includes endocrine therapy combined with a CDK4/6 inhibitor, achieving progression-free survival (PFS) of 24-33 months with preserved quality of life. Although CDK4/6 inhibitors are generally well tolerated, they are associated with hematologic and gastrointestinal toxicities. We describe a patient who developed features of chronic immune-mediate polyradiculoneuropathy associated with neurofascin antibodies following initiation of palbociclib. METHODS: We conducted a detailed clinical review of a patient with metastatic HR+/HER2- breast cancer who developed progressive bilateral upper and lower extremity weakness after starting palbociclib. Clinical presentation, laboratory findings, imaging studies, electrodiagnostic testing, and treatment response were reviewed. RESULTS: A 43-year old female with metastatic HR+/HER2- breast cancer developed asymmetric progressive weakness and sensory symptoms approximately two weeks after initiating palbociclib. Electrodiagnostic testing demonstrated a mixed axonal and demyelinating sensorimotor polyneuropathy meeting EAN/PNS criteria for an acquired inflammatory demyelinating polyradiculoneuropathy. Initial diagnostic considerations included acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and multifocal CIDP (formerly termed multifocal acquired demyelinating sensory and motor neuropathy [MADSAM]). Despite initial improvement following treatment with IVIG, the patient experienced continued neurologic progression requiring plasmapheresis, repeat IVIG, high-dose corticosteroids, and rituximab. Subsequent testing demonstrated anti-neurofascin-155 and anti-neurofascin-186 antibody positivity. Longitudinal follow-up demonstrated significant functional recovery following rituximab therapy. CONCLUSION: This case suggests a possible association between palbociclib exposure and the development of chronic immune-mediate polyradiculoneuropathy associated with neurofascin antibodies. Clinicians should consider immune mediated neuropathies in patients receiving CDK4/6 inhibitor therapy who develop weakness, sensory deficits, and areflexia. Further investigation is warranted to better characterize potential immunologic effects of CDK4/6 inhibition and their relationship to autoimmune neurologic disease.
Language: English
Subfield: Clinical Neurology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $4,190
OpenAlex ID: W7225232535