Shares of Celgene Corp. (CELG) - Get Report  stumbled in early trading on Wednesday, Feb. 28, following news that the U.S. Food and Drug Administration had rejected the pharmaceutical firm's new drug application for Ozanimod in relapsing forms of multiple sclerosis. 

Summit, N.J.-based Celgene announced after the close on Tuesday that it had received a refusal-to-file letter from the FDA.

The stock was down almost 7% to $89.16 on Tuesday morning and is down almost 15% so far this year.  

The FDA, upon its preliminary review, "determined that the nonclinical and clinical pharmacology sections in the NDA were insufficient to permit a complete review," Celgene said.  The company said it plans to seek guidance from the agency on the additional information needed to resubmit the application.

SunTrust Robinson Humphrey Inc. Yatin Suneja downgraded his rating to hold from buy on the heels the announcement.

"Following pipeline setbacks in late 2017, ozanimod was central to our bull thesis to re-accelerate growth in the [inflammation and immunology] franchise and provide much-needed diversification away from myeloma," Suneja wrote in a note. "Given the delay, we are lowering our ozanimod peak sales estimate to ~$3.5B (from ~$5B)." 

One of the setbacks Suneja was referring to was Celgene's decision to discontinue the Phase 3 Revolve clinical study of GED-0301 (mongersen) in Crohn's disease and the extension trial, following a recommendation by the Data Monitoring Committee.

Tuesday's news on Ozanimod is "a pretty negative headline but presumably this is fixable and merely a delay and yet another short-term problem that does not inspire Street confidence these days," wrote Jefferies LLC analyst Michael Yee in a note.