(Corrects 7th paragraph to show Novartis could file BAF312 with regulators in H1 2017, from expects H1 2017 approval)
March 28 (Reuters) - The U.S. Food and Drug Administration (FDA) on Tuesday approved Roche Holding AG's multiple sclerosis (MS) drug Ocrevus, putting the potential blockbuster drug back on track after a delay caused by regulators' concerns over manufacturing issues.
The infusible drug, known chemically as ocrelizumab, becomes the first U.S.-approved medicine for the primary progressive form of the neurological disease (PPMS). It is also approved to treat the most common form of the disease, known as relapsing-remitting multiple sclerosis (RRMS).
Roche said Ocrevus will be available to people in the United States within two weeks.
The drug's entry into the U.S. market was delayed by three months when the FDA in late December pushed back its deadline for an approval decision, saying the commercial manufacturing process for Ocrevus was not yet ready.
Ocrevus, an immunosuppressive drug that reduces the immune system's assault on the body's own neurons, could become a mainstay treatment for MS and help offset falling revenue from Roche's top-selling cancer drugs Rituxan, Avastin and Herceptin, that will soon face competition from cheaper biosimilar versions.
Analysts forecast annual sales exceeding $3 billion by 2021, according to Reuters data.
Roche rival Novartis AG is also developing its own MS treatment, BAF312, for secondary progressive multiple sclerosis. It could file for regulatory approval in the first half of 2017, Novartis has said, although the official filing target for BAF312 remains 2019.
Other companies are also seeking new drug alternatives for different forms of MS, including GeNeuro SA.
The most popular MS treatment in the United States currently is Copaxone, made by Teva Pharmaceuticals Industries Ltd .
Roche said in the PPMS study that patients who took Ocrevus were 47 percent more likely than those who received a placebo to show no evidence of disease progression.
The company said its trials among RRMS patients showed 75 percent more patients reached "no evidence of disease activity" status when taking Ocrevus compared with those using Merck & Co Inc's Rebif, an older therapy.
The drug's path to approval has not been straightforward.
In 2010, Roche and Biogen Inc suspended trials of the biotech medicine against rheumatoid arthritis after patients died from fatal opportunistic infections. Trials were also suspended for lupus nephritis patients.
Against multiple sclerosis, however, Roche has said the fatal side effect was not repeated. Infusion-related reactions were among the main adverse side effects seen in MS trials. (Reporting by John Miller in Zurich and Akankshita Mukhopadhyay in Bengaluru; Additional reporting by Bill Berkrot in New York; Editing by Lisa Shumaker and Bill Rigby)