Swiss drugmaker Roche has big ambitions beyond treating cancer, where it is already global market leader, and believes it has a winner in a new multiple sclerosis drug.

While the market for multiple sclerosis (MS) treatments is relatively crowded, Roche thinks its drug ocrelizumab, for which clinical data will be unveiled next month, can grab share by offering top-of-the-range potency with minimal side effects.

"This is a huge opportunity for us," Chief Executive Severin Schwan said in an interview.

"MS is a big market of over $20 billion (a year) and we believe the profile of our medicine in terms of efficacy and safety is pretty unique. I think this is very good for patients and there is a huge commercial potential for this medicine."

So far, Roche has only said that ocrelizumab hit its targets in final-stage clinical trials by cutting relapses and disability progression when compared with Merck KGaA's established treatment Rebif.

Full details of the new drug's efficacy and safety will be disclosed at the Oct. 7-10 annual meeting of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) in Barcelona.

"This is the most important (clinical) read-out this year, without any doubt," Schwan said.

Safety is crucial to success.

Because MS is caused by abnormal immune system attacks on the protective sheath surrounding nerve cells, treatments need to adjust the body's immune response, which can lead to serious side effects.

In fact, ocrelizumab was dropped from development as a treatment for rheumatoid arthritis some years ago because of its link to infections. But patients, and treatments, are very different for MS and safety is not seen as an issue this time.

"It's wonderful from a safety point of view," Schwan said. "We have a safety profile which is similar to the interferons, to Rebif, which is considered the safest MS drug class."

He expects ocrelizumab to compete with injectable drugs, such as Biogen's Tysabri and Sanofi's Lemtrada, which can have major side effects, as well as pills such as Novartis' Gilenya and Biogen's Tecfidera.

LONG SHOT IN PROGRESSIVE MS

While the successful Roche studies used ocrelizumab to treat relapsing-remitting MS, the medicine is also being tested in people with primary progressive MS (PPMS), a different form of the disease affecting around one in six patients.

Initial results in PPMS will also be presented in Barcelona, although Schwan said results of that trial were unknown and success was a long shot as there were no approved drugs for the condition.

"As a company, we don't have it in our plan. It would be pure upside," he said.

Ocrelizumab is delivered twice-yearly via an intravenous drip. While this may be cumbersome it reduces the risk patients will skip their medication, particularly between relapses.

Roche is to seek marketing approval for the new drug in the first quarter of 2016, implying a potential launch about a year later.

Current consensus forecasts point to sales of $720 million in 2020, according to Thomson Reuters Cortellis, but that could rise significantly if ocrelizumab is as successful as Schwan hopes.