Safety and efficacy of erythropoietin for the treatment of patients with optic neuritis (TONE): a randomised, double-blind, multicentre, placebo-controlled study
RCT(n=108) found erythropoietin as adjunct to corticosteroids conveyed neither functional nor structural neuroprotection in visual pathways after optic neuritis (mean pRNFL atrophy 15.93 v 14.65μm placebo; p=0.76;mean low contrast letter acuity scores 49.60 v 49.06, respectively)
Source:
The Lancet Neurology
SPS commentary:
Erythropoietin, a human cytokine with neurotrophin-like effects, has been reported to ameliorate the manifestations of neurodegeneration in an experimental autoimmune encephalomyelitis rodent model, and reduced retinal nerve fibre layer (RNFL) thinning in a phase 2 study of optic neuritis patients.
According to a commentary, a negative study is often cause for reflection and this study provides lessons for future studies of potential neuroprotective agents in patients with optic neuritis at risk of being diagnosed with multiple sclerosis. It notes that the investigators completed a methodologically sound clinical trial that showed the absence of treatment effect with erythropoietin, and should be lauded for demonstrating how the visual system can be comprehensively investigated to explore the efficacy of new therapeutic agents in this population. It suggests that future design considerations for trials using visual outcomes to assess neuroprotective therapies include: the value of MRI in quantifying the effects of anterior and posterior visual pathway lesions on outcome measures; the importance of serological characterisation of optic neuritis subtypes; the need to control for patient-related factors known to cause inner retinal thinning; and the potential for including other biomarkers of neuroaxonal injury, such as serum neurofilament light chain.