Extensive cervical myelitis following pembrolizumab treatment after prior radiotherapy: a case report

INTRODUCTION: Immune checkpoint inhibitors represent a significant therapeutic advancement in the management of multiple malignancies. However, they are associated with rare but potentially severe neurological immune-related adverse events. CASE PRESENTATION: We report the case of a patient in his 70s with metastatic lung adenocarcinoma who developed extensive cervical myelitis following pembrolizumab immunotherapy in the context of prior cervical radiotherapy. Spinal magnetic resonance imaging (MRI) revealed extensive inflammatory lesions involving the cervical spinal cord with extension to the thoracic region. MANAGEMENT AND OUTCOMES: Despite the discontinuation of pembrolizumab and the early initiation of aggressive immunosuppressive therapy including high-dose corticosteroids, plasmapheresis, intravenous immunoglobulin and tocilizumab, the clinical course was rapidly and progressively unfavourable. CONCLUSION: This case highlights the potential severity of immune-mediated myelitis, raises the question of whether there is a deleterious interaction between immune checkpoint inhibitor and prior radiotherapy, and illustrates the limitations of current therapeutic strategies in cases of refractory forms.