* Final-stage trials show efficacy of ocrelizumab vs Rebif
* Roche plans to seek regulatory approval in Q1 2016
* Sales forecast to hit nearly $800 mln by 2020 (Adds market reaction, analyst comment)
ZURICH, June 30 (Reuters) - A drug being developed by Roche to treat multiple sclerosis (MS) met its main targets in two final-stage clinical trials, boosting the Swiss company's hopes of expanding beyond its core cancer business.
The Phase III trials for ocrelizumab showed the drug, which is delivered twice-yearly via an intravenous drip, slowed relapses as well as the progression of disabilities that come with MS when compared with Rebif, an established injectable treatment, the company said on Tuesday.
Rebif, made by Germany's Merck KGaA, is already battling stiff competition from a new generation of oral drugs against the debilitating disease.
"Based on these compelling results, we plan to submit the data for review to U.S. and EU regulatory authorities in the first quarter of 2016," said Sandra Horning, Roche's chief medical officer and head of global product development.
Roche stock rose 0.2 percent to 264 Swiss francs in early trading, outperforming a lower European sector index.
Deutsche Bank analysts said the drug could have best-in-category efficacy and the data helped remove some of the risk surrounding forecasts.
"Importantly, no safety signals were reported, (the main concern being serious infections)," they said in a client note.
Analysts' consensus forecast is for ocrelizumab to make $796 million of sales by 2020, according to Thomson Reuters Cortellis.
Roche said the drug showed a similar number of adverse effects as Rebif, or interferon, the most common being infusion-related reactions, ones involving the immune system. The incidence of serious adverse reactions associated with the drug, such as serious infections, was also similar.
Roche has several promising non-cancer drugs in late-stage trials, including lampalizumab for a serious eye disease and asthma drug lebrikizumab.
The Basel-based company, the world's biggest maker of cancer drugs, needs to keep rolling out new medicines if it is to head off the threat posed by biosimilars, cheap copies of biotech drugs that could erode its blockbuster cancer treatments such as Rituxan and Herceptin.
Besides looking at other diseases, Roche is pinning hopes on a new class of cancer drugs that harness the body's immune system to fight tumours. (Reporting by Katharina Bart. Additional reporting by Michael Shields; Editing by Keith Weir and Mark Potter)