The use of tocilizumab, an anti-interleukin 6 (IL-6) receptor antibody, may reduce the annualized relapse rate (ARR) in patients with neuromyelitis optica spectrum disorder (NMOSD). Furthermore, baseline plasma glial fibrillary acidic protein (pGFAP) level could be an important biomarker for predicting the success of tocilizumab therapy.
Both of these findings were reached in a study recently published in the Journal of Neurology.
Currently, the astrocytic water channel aquaporin-4 (AQP4) antibody is the most common therapeutic target for relapse prevention in patients with NMOSD, but the high NMOSD relapse rates have created an interest in assessing new potential therapeutic targets. IL-6 receptor blockade has been proposed as a possible therapeutic alternative for NMOSD.
IL-6 favors the differentiation of B cells into AQP4 antibody-producing plasmablasts and regulates GFAP levels, which are associated with astrocyte pathology. Furthermore, evidence suggests that patients with NMOSD have increased IL-6 levels in their cerebrospinal fluid.
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Several trials have assessed the efficacy of tocilizumab in patients with NMOSD, with promising results. However, the time periods studied in these trials were short and did not provide information on the long-term efficacy of the drug. Therefore, the authors aimed to assess relapse risk factors for patients receiving tocilizumab therapy and explore potential prognostic biomarkers for relapse.
The study collected the medical records of 65 patients with a confirmed diagnosis of NMOSD who had received tocilizumab treatment between 2017 and 2019. The primary outcome measure assessed in the study was ARR. Blood samples were collected before beginning tocilizumab treatment to measure pGFAP levels.
After approximately 34 months of treatment, over 75% of patients had experienced no relapses, approximately 20% had over 20 relapses, and 15% had 1 relapse, which was a significant decrease in the ARR. There was no significant difference in age, disease severity, or disease duration between patients who relapsed and those who did not.
A survival curve analysis determined that the most significant relapse risk factors were not receiving concomitant corticosteroid therapy, higher baseline pGFAP levels, and prolonged infusion intervals.
“This study confirmed the effectiveness of tocilizumab in patients with NMOSD in a real-world setting and explored the risk factors associated with NMOSD relapses during long-term tocilizumab therapy management,” the authors wrote.
Yang S, Zhang C, Zhang TX, et al. A real-world study of interleukin-6 receptor blockade in patients with neuromyelitis optica spectrum disorder. J Neurol. Published online September 6, 2022. doi:10.1007/s00415-022-11364-9