CAMBRIDGE, Mass. (AP) — Biogen Idec says that federal regulators have approved the specialty drugmaker’s new treatment for people with relapsing forms of multiple sclerosis.

The company said Friday that the Food and Drug Administration cleared the injectable drug, dubbed Plegridy, after reviewing results from a study that involved more than 1,500 people with the disease.

Multiple sclerosis is a disease of the immune system in which the body attacks the brain and spinal cord.

Its symptoms can come and go, often reappearing months later.

The European Commission recently approved Plegridy.

Biogen also markets the multiple sclerosis drugs Avonex and Tysabri.

Shares of Biogen Idec Inc. ended regular trading up $5.46, or 1.6 percent, to $342.47 on Friday.

The stock is up 22 percent this year.

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