Celgene Corp. shares dropped nearly 6% in heavy Monday morning trade after a Morgan Stanley report predicted a one- to three-year delay on any new attempt to file for U.S. approval of the company’s drug ozanimod. Celgene recently filed for Food and Drug Administration approval of ozanimod in relapsing multiple sclerosis, but the FDA wouldn’t let it, saying there were insufficient sections in the drug application. Celgene will probably need to re-run preclinical toxicology studies, delaying re-filing by at least a year if not longer, “given the timeline to start the study, produce the study reports and refile,” said Morgan Stanley analyst Matthew Harrison, a determination he said he made based on previously published ozanimod preclinical toxicology and metabolite studies. Ozanimod is seen as a critical product for Celgene. The company has sought to bulk up its drug pipeline after the failure of other key drugs last year. Celgene shares have dropped 15% over the last three months, compared with a 5.6% drop in the S&P 500 and a 6.6% drop in the Dow Jones Industrial Average .