New Medication Aims to Re-Myelinate the Optic Nerve after Optic Neuritis
8:58 AMThere is never a shortage of hope in the pharmaceutical world, and the recent reports on anti-LINGO-1(Biogen Idec) are full of promise for patients that have suffered vision loss from optic neuritis events. The drug targets the LINGO-1 protein that is found in the human central nervous system and is known to inhibit myelination of axons and regeneration of axons. Myelin is the important sheathing found along axons to speed transmission of information along the nerve. By blocking LINGO-1, the medication hopes to promote myelin production and potentially regenerate axon tissue -- a benefit that if successful could find uses in medical conditions from MS to Alzheimer's.
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| LINGO-1 protein via |
Phase II studies showed mixed readings when reported last week in the RENEW trial, targeting acute optic neuritis events in patients with MS. Anti-LINGO-1 was injected intravenously in a study that lasted 24 weeks and included 82 patients. The main target of the study was an improved transmission speed of information along the optic nerve to the brain, as measured by VEP technology. The study reported a 34% improvement in the recovery of optic nerve latency -- meaning that patients in the treatment group did have better transmission speed on their VEP tests over those in the placebo group. But other secondary endpoints showed no improvement at the 24 week mark: OCT testing showed no improvement in nerve fiber layer thickness, and visual acuity and low contrast sensitivity did not show improvement.
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| VEP testing is used to measure transmission of information from the eye to the brain based on responses to patterned images at the level of your visual cortex. If your brain responds to the image (measured with electrodes placed in the area), then we know exactly when your brain "sees" the image via |
Despite the limits of the first report, there is still much to be learned and much to be potentially excited about for future. Researchers will continue to follow these patients with time to determine if longer intervals of use will show improvement in visual acuity or functional measurements, and if the nerve tissue continues to show improved transmission speed as the study proceeds. As an optometrist, the results that OCT testing didn't show an increase in nerve fiber layer thickness did not really surprise me -- there is no myelin sheathing of the nerve fiber layer inside the eye, so remyelination of tissue is not really a target for these nerve layers. If there is some regeneration of nerve tissue, we may see it with OCT, but the timeline for regeneration (if possible) may be much longer than just 24 weeks. The fact that VEP transmission speed did show improvement still leaves hope that this medication can help patients suffering from optic neuritis related vision loss.
There will be a larger readout in the spring of the concurrent SYNERGY study that used anti-LINGO-1 concurrently with commonly used treatment Avonex in patients with chronic MS.
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