Biogen shares fall after optic nerve study results seen as mixed

(Reuters) - Biogen Idec Inc said an experimental drug showed evidence of biological repair of the optic nerve in patients with acute inflammation of the optic nerve, but shares fell as analysts wondered how promising the mid-stage study results were. The drug is also being tested in patients with multiple sclerosis, an inflammatory disease that attacks the protective covers of nerve cells, and investors have been watching for the results of the acute optic neuritis study for an indication of how the treatment might fare in that study. The trial on the drug, called Anti-LINGO-1, demonstrated an improvement in recovery of optic nerve latency, or the time it takes for a signal to travel from the retina to the visual cortex, Biogen said. The company said it showed a 34 percent improvement versus a placebo treatment. The company said that in the intent-to-treat population, which includes patients who did not complete the study, there was a positive trend, but results did not reach statistical significance. The drug failed to meet the trial's secondary endpoint, including change in thickness of the retinal layers and visual function, Biogen said. "These data certainly do not make us more positive that it will work in MS. If anything, the only clinical evidence we have on LINGO suggests it is less likely to work," UBS AG analyst Matthew Roden wrote in a research note. Biogen shares fell 2.4 percent to $345 after rising as much as 6 percent in premarket trading. Biogen described the study results as being positive. “This is the first clinical trial to provide evidence of biological repair in the central nervous system by facilitating remyelination following an acute inflammatory injury,” Alfred Sandrock, Biogen chief medical officer said in a statement. Remyelination is the regeneration of the insulating myelin sheath of a nerve. The most common cause of acute optic neuritis is multiple sclerosis, an area where Biogen has produced the leading drugs Tecfidera and Tysabri. Wells Fargo analyst Brian Abrahams described the data as mixed but said that the signal of activity was encouraging. Evercore ISI analyst Mark Schoenebaum said in a research note the data was "encouraging, but certainly not definitive." Biogen said there were 82 patients in the trial, that the drug was generally well tolerated and that three people experienced severe adverse effects. A Biogen spokeswoman described the number of people who did not finish the study as being low, but didn't provide a figure. (Reporting by Caroline Humer; Editing by Bernadette Baum)