An autoimmune-based, paraneoplastic neurologic syndrome following checkpoint inhibition and concurrent radiotherapy for merkel cell carcinoma: case report

• Published in: Strahlentherapie und Onkologie 2020-07, Vol.196 (7), p.664-670
• Main Authors: Sherry, Alexander D., Bezzerides, Michael, Khattab, Mohamed H., Luo, Guozhen, Ancell, Kristin K., Kirschner, Austin N.
• Format: Article
• Language: English
• Subjects: Aged; Antibodies, Monoclonal, Humanized - adverse effects; Antibodies, Monoclonal, Humanized - therapeutic use; Anticancer properties; Antineoplastic Agents, Immunological - adverse effects; Antineoplastic Agents, Immunological - therapeutic use; Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Autoimmune Diseases of the Nervous System - etiology; Autoimmune Diseases of the Nervous System - immunology; Axilla; Carboplatin - administration & dosage; Carcinoma, Merkel Cell - drug therapy; Carcinoma, Merkel Cell - radiotherapy; Carcinoma, Merkel Cell - secondary; Case reports; Case Study; Combined Modality Therapy; Deglutition Disorders - etiology; Etoposide - administration & dosage; Fatal Outcome; Fingers; Hallucinations; Hallucinations - etiology; Humans; Immune system; Immunotherapy; Lymphatic Metastasis - diagnostic imaging; Lymphatic Metastasis - radiotherapy; Male; Medicine; Medicine & Public Health; Monoclonal antibodies; Neuralgia - drug therapy; Neuralgia - etiology; Nutrition; Oncology; Palliative Care; Paraneoplastic Syndromes, Nervous System - etiology; Paraneoplastic Syndromes, Nervous System - immunology; Parenteral Nutrition, Total; Pneumonia, Aspiration - etiology; Positron Emission Tomography Computed Tomography; Radiation therapy; Radioimmunotherapy - adverse effects; Radiotherapy; Radiotherapy, High-Energy; Radiotherapy, Intensity-Modulated - adverse effects; Skin cancer; Skin Neoplasms - drug therapy; Skin Neoplasms - radiotherapy; Skin Neoplasms - secondary
• ISSN: 0179-7158; 1439-099X
• DOI: 10.1007/s00066-020-01582-3

Purpose Merkel cell carcinoma is highly sensitive to both radiation and immunotherapy. Moreover, concurrent radioimmunotherapy may capitalize on anti-tumor immune activity and improve Merkel cell treatment response, although an enhanced immune system may cross-react with native tissues and lead to significant sequelae. Methods Here we present a case study of a patient with metastatic Merkel cell carcinoma treated with radiotherapy concurrent with pembrolizumab. Results After radioimmunotherapy, the patient developed sensory neuropathy, visual hallucinations, and mixed motor neuron findings. Neurologic dysfunction progressed to profound gastrointestinal dysmotility necessitating parenteral nutrition and intubation with eventual expiration. Conclusion This case represents a unique autoimmune paraneoplastic neurologic syndrome, likely specific to neuroendocrine tumors and motivated by concurrent radioimmunotherapy. Recognition of the potential role of radioimmunotherapy may provide an advantage in anticipating these severe sequelae.