A randomized, double-blind, phase 2 study of erythropoietin in optic neuritis

Based on findings in animal models of autoimmune optic nerve inflammation, we have assessed the safety and efficacy of erythropoietin in patients presenting with a first episode of optic neuritis.

Patients with optic neuritis who attended the University Hospitals of Homburg/Saar, Göttingen, or Hamburg (Germany) were included in this double-blind, placebo-controlled, phase 2 study (ClinicalTrials.gov, NCT00355095). They were randomly assigned to groups receiving either 33,000IU recombinant human erythropoietin intravenously daily for 3 days or placebo as an add-on therapy to methylprednisolone. The primary outcome parameter was change in retinal nerve fiber layer (RNFL) thickness after 16 weeks. Secondary outcome parameters included optic nerve atrophy as assessed by magnetic resonance imaging, and changes in visual acuity, visual field, and visual evoked potentials (VEPs).

Forty patients were assigned to the treatment groups (21/19 erythropoietin/placebo). Safety monitoring revealed no relevant issues. Thirty-seven patients (20/17 erythropoietin/placebo) were analyzed for the primary endpoint according to the intention-to-treat protocol. RNFL thinning was less apparent after erythropoietin treatment. Thickness of the RNFL decreased by a median of 7.5μm by week 16 (mean ± standard deviation, 10.55 ± 17.54μm) compared to a median of 16.0μm (22.65 ± 29.18μm) in the placebo group (p = 0.0357). Decrease in retrobulbar diameter of the optic nerve was smaller in the erythropoietin group (p = 0.0112). VEP latencies at week 16 were shorter in erythropoietin-treated patients than in the placebo group (p = 0.0011). Testing of visual functions revealed trends toward an improved outcome after erythropoietin treatment.

These results give the first indications that erythropoietin might be neuroprotective in optic neuritis.