Motor polyradiculopathy during pembrolizumab treatment of metastatic melanoma
Funding: This case report received no specific grant from any funding agency.
Conflicts of Interest: Drs. Sepúlveda, Martinez-Hernandez, Gaba, Victoria, Sola-Valls, Casanova-Molla, Falgàs and Graus report no disclosures.
ABSTRACT
Introduction
Pembrolizumab, a monoclonal antibody directed against the immune checkpoint programmed cell death-1 receptor (PD-1), has improved survival in patients with advanced melanoma. Neuromuscular immune-mediated side effects have been rarely reported.
Methods
We describe a 44-year-old man with metastatic melanoma who presented with progressive muscle weakness after 23 doses of pembrolizumab.
Results
The patient developed asymmetric, proximal muscle weakness and atrophy in all four limbs. Cerebrospinal fluid examination showed albuminocytologic dissociation. MRI revealed contrast enhancement of the lumbosacral roots. Electrodiagnostic studies demonstrated widespread fibrillation potentials in all four limbs, suggesting a generalized motor polyradiculopathy. Despite pembrolizumab discontinuation and treatment with steroids and intravenous immunoglobulin, limb weakness worsened. Electrodiagnostic studies were repeated, and showed marked and diffuse axonal motor damage. Seven weeks after clinical onset the patient was treated with plasma exchanges. He showed no further deterioration.
Discussion
We report a severe motor polyradiculopathy associated with an anti-PD-1 agent that expands the spectrum of neuromuscular complications of this class of drugs. Muscle Nerve 56: E162–E167, 2017
