Court building

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What happened

Shares of Momenta Pharmaceuticals (NASDAQ:MNTA) are up over 20% at 12:28 p.m. EST after the company announced that the U.S. District Court invalidated four of Teva Pharmaceutical's (NYSE:TEVA) patents on the three-times-weekly version of its multiple sclerosis drug Copaxone. Teva's shares are down 3% on the news.

So what

Invalidating the patents moves Momenta and its partner Novartis (NYSE:NVS) one step closer to being able to sell their generic version of the drug, which they call Glatopa. The duo already sells a generic of the lower-dose daily version of Copaxone, but the three-times-weekly version is more popular. Teva Pharmaceutical has also been able to lock Momenta and Novartis out of some of the market by setting up deals with pharmacies that cover both drugs, so getting a generic version of the three-times-weekly version should also increase their penetration into the market for daily version.

There's still a patent on the three-times-weekly version of Copaxone that Mylan (NASDAQ:MYL), which is also developing a generic version of it, asked the Patent Trial and Appeal Board to review. A ruling on that patent should be released in April.

Now what

Teva Pharmaceutical said it plans to appeal the decision, so a final ruling on all the patents is likely a ways off. Nevertheless, Novartis and Momenta can still launch as soon as they receive Food and Drug Administration approval, but it would be an at-risk launch, subject to damages if Teva wins during the appeals process.

Brian Orelli has no position in any stocks mentioned. The Motley Fool recommends Momenta Pharmaceuticals, Mylan, and Teva Pharmaceutical. The Motley Fool has a disclosure policy.