Zurich : Roche's new multiple sclerosis (MS) drug could be approved in the United States this year, earlier than previously forecast, the Swiss drugmaker said, after winning the U.S. regulator's priority review status for the medicine.

The U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) accepted marketing applications for Roche's Ocrevus medicine, for both the relapsing-remitting and primary-progressive forms of MS, the company said in a statement.

With FDA fast-track review, Roche said U.S. approval for Ocrevus now could come by Dec. 28, faster than the company's previous estimate of early 2017.

"It offers the hope that soon we'll be able to bring ocrelizumab to patients," said Paulo Fontoura, who heads Roche's clinical development program in neuroscience, in an interview, referring to the chemical name for Ocrevus.

"We feel strongly based on the data that this is a medicine that has the potential to really change the way MS is being treated right now."

Ocrevus' approval in Europe will likely stretch into the third quarter of 2017, Fontoura said.

Roche submitted its application for Ocrevus last year, before the EMA initiated its own fast-track "Prime" approval process to cut the time it takes promising new medicines to get to market.

"That's a very new process for the EMA," Fontoura said. "It hasn't really had an impact yet."

Winning regulators' backing for Ocrevus is a pivotal part of Roche's strategy to develop new drugs for cancer and other diseases to replace revenue from older medicines such as Rituxan whose patents are expiring, leaving them exposed by late 2017 to cheaper biosimilar drug copies.

MORE OPTIMISTIC

In an interview last week, Chief Executive Severin Schwan said he had grown steadily more optimistic that his company's new drugs would boost revenue even amid the biosimilars threat.

Ocrevus sales could hit 3.7 billion Swiss francs ($3.8 billion) by 2022, according to Reuters data.

Roche has previously said late-stage trials with Ocrevus show it works better than rival drugmaker Merck's Rebif in patients suffering from relapsing MS.

The drug, administered by intravenous infusion every six months, would be the first approved treatment for the primary-progressive form of the disease.

About 85 percent of those diagnosed with MS suffer from relapsing-remitting MS, while 10 percent suffer from primary-progressive MS.