"This sort of opens the door for us."

The Food and Drug Administration on Tuesday approved the first treatment for primary progressive multiple sclerosis (PPMS), a severe form of the neurological condition that had no approved treatment until now.

This sort of opens the door for us,” Dr. Fred Lublin, an investigator for the clinical trials and director of the Corinne Goldsmith Dickinson Center for Multiple Sclerosis at Mount Sinai Hospital, told The New York Times. “Once we open that door, then we do better and better and better. It’s a very encouraging result.”

Clinical trials found a 24 percent lower risk of disability progression in participants with PPMS who took the new drug, compared with those who received a placebo.

The list price for ocrelizumab, which will be sold under the brand name Ocrevus by Genentech, is $65,000 per year. (Genentech is part of the Swiss pharmaceutical company Roche.) The drug is also approved for relapsing-remitting multiple sclerosis, the most common form of the disease. It’s expected to be on the market within two weeks.

More than 400,000 people in the United States and 2.3 million people worldwide have MS, according to the Multiple Sclerosis Foundation. About 10 percent of patients are diagnosed with PPMS at the onset of their disease. PPMS is progressive and not marked by relapses or remissions.

Although women are twice as likely to have MS as men, the rate of people with PPMS is equal among men and women, with onset usually occurring from ages 35 to 39.

“The FDA’s approval of Ocrevus is the beginning of a new era for the MS community and represents a significant scientific advance,” Sandra Horning, Roche’s chief medical officer, told Reuters.

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