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May 22 (Reuters) - Celgene Corp said its oral drug to treat relapsing multiple sclerosis met the main goal in a second late-stage study, bringing the U.S. biotech a step closer to launching a potential blockbuster.

The drug, ozanimod, reduced annualized relapse rate in patients with relapsing multiple sclerosis, compared to Biogen Inc's Avonex, the company said on Monday.

However, Celgene said ozanimod was not statistically significant to Avonex in disability progression.

Celgene's shares were marginally down in premarket trading.

Investors were focusing on whether the drug would show disability benefit over Avonex, Evercore ISI analyst Umer Raffat wrote in a note to clients on Monday.

Ozanimod came Celgene's way following its $7.2 billion acquisition of Receptos Inc in 2015.

Celgene said on Monday it expected to file for U.S. marketing application by the end of this year.

The company said in February that another late-stage study testing ozanimod in relapsing multiple sclerosis had succeeded.

William Blair analyst John Sonnier had then estimated that the global commercial opportunity for relapsed multiple sclerosis could be over $25 billion by 2020.

The U.S. biotechnology company is also testing Ozanimod in ulcerative colitis and Crohn's disease, which Sonnier had projected to be a $15 billion market worldwide in 2020. (Reporting by Divya Grover in Bengaluru; Editing by Sriraj Kalluvila)