(Reuters) - Biogen Inc and partner Eisai Co Ltd said on Friday the U.S. Food and Drug Administration has extended the review period for their experimental Alzheimer’s disease treatment by three months from March. Biogen’s shares rose about 10% as the FDA extension raised some hopes that the drug may still be approved despite a panel of experts to the FDA voting against it in November. “Our key takeaway is that if the FDA would have wanted to reject the drug, we would have heard the decision by now,” said Truist analyst Robyn Karnauskas. An FDA approval would make the drug, aducanumab, the first new treatment for Alzheimer’s in decades and the first that appears to be able to slow progression of the fatal, mind-wasting condition that affects millions of people. The road to getting a regulatory approval for the drug has been rocky, with the companies scrapping two studies of the therapy in March 2019 and reversing that decision a few months later. The expert panel to the FDA had voted “no” to three questions related to whether a single successful large trial of aducanumab was enough evidence of the drug’s effectiveness given the clear failure of a second large study. Not all analysts saw the update as positive news for aducanumab. “With a permanent FDA head yet to be named, one could easily interpret this delay as either waiting for administrative cover or simply assuaging patient (advocacy) groups that all avenues were pursued before rejecting,” said Piper Sandler analyst Christopher Raymond. The FDA is not obligated to follow the recommendations of the panel, but usually does. The agency will now decide on the marketing application for aducanumab by June 7.