Canadian researchers have reported the first case of a patient developing multiple sclerosis (MS) while taking tocilizumab for rheumatoid arthritis.
A 48-year-old woman with a 20-year history of rheumatoid arthritis was seen for right hemisensory symptoms that began as numbness and pain on her right foot that spread to her trunk, arm, and face over a week, Dr. Philippe Beauchemin and Dr. Robert Carruthers of the University of British Columbia, Vancouver, noted in Multiple Sclerosis Journal. She had received many treatments for rheumatoid arthritis, including hydroxychloroquine, etanercept, and adalimumab. She also was on methotrexate, vitamin D, naproxen, and dexlansoprazole. MRI showed 20 lesions consistent with the diagnosis of MS. Doctors immediately discontinued tocilizumab and methotrexate. Three months later, another MRI showed two new lesions confirming MS diagnosis.
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“There is absolutely no proof of a causal relationship between tocilizumab and MS in this patient, but it is also not excluded that tocilizumab might have caused secondary autoimmunity in CNS,” the authors wrote. The drug is in efficacy trials for patients with neuromyelitis optica spectrum disorder.
Two scenarios could explain this potential relationship, according to an accompanying commentary by Dr. Manuel Comabella of the Multiple Sclerosis Center of Catalonia, Vall d’Hebron University Hospital, Barcelona. The patient may have developed demyelinating lesions as a consequence of previous exposure to anti-TNF agents, and MS was later precipitated by treatment with tocilizumab; or that the drug itself can trigger a demyelinating disorder. “IL-6 may have immunosuppressive properties … that when absent by the effect of anti-IL6 agents, predisposes the individual to demyelinating conditions.”
Read the article in Multiple Sclerosis Journal (doi: 10:1177/1352458515623862).