Biogen Idec (Nasdaq: BIIB) sure knows how to name its clinical trials. Last April, DEFINE, a clinical trial testing the company's oral multiple sclerosis drug BG-12, defined the stellar efficacy and safety profile for the drug. And then yesterday, CONFIRM, a second clinical trial for BG-12, confirmed the results of DEFINE.

Good thing the acronyms didn't spell out VAGUE and CONTRADICT.

Most confirmatory clinical trials don't add much value since the cat's already out of the bag, but Biogen jumped more than 9% yesterday, a $2.4 billion increase in value. The reason for the jump: The results from DEFINE were so good that people, myself included, wondered whether Biogen really could replicate the data.

I guess the cat really is out of the bag now. Since the results of DEFINE were announced, Biogen is up 60%, while the Dow Jones (INDEX: ^DJI) has been essentially flat.

For good reason, BG-12 looks like it has blockbuster potential. The drug reduced the annualized relapse compared with placebo by 44% or 51%, depending on whether it was dosed twice or three times a day. By comparison, Teva Pharmaceuticals' (Nasdaq: TEVA) Copaxone reduced the annualized rate by only 29%.

And let's not forget that BG-12 is taken orally, while other drugs like Copaxone, Biogen and Elan's (NYSE: ELN) Tysabri, and Merck KGaA and Pfizer's (NYSE: PFE) Rebif have to be injected or infused. BG-12 is going to make many needle-phobic multiple sclerosis patients very happy. We haven't seen a head-to-head comparison with Novartis' (NYSE: NVS) Gilenya, the only oral treatment for slowing multiple sclerosis progression, but the data looks good enough for BG-12 to take some of Gilenya's market as well.

There are no sure things with the Food and Drug Administration, but BG-12 sure looks like it has an excellent chance of gaining approval late next year. You can follow its progress through the regulatory system by adding it to My Watchlist, which will help you keep track of all our Foolish analysis on Biogen.

Fool contributor Brian Orelli holds no position in any company mentioned. Check out his holdings and a short bio. The Motley Fool owns shares of Teva Pharmaceutical Industries. Motley Fool newsletter services have recommended buying shares of Elan, Pfizer, Novartis, and Teva Pharmaceutical Industries. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.