When is six better than 12? When we're talking about the annual number of injections that patients with the wet version of age-related macular degeneration (AMD) have to get in their eyes.

Regeneron Pharmaceuticals (Nasdaq: REGN) was up nearly 20% yesterday, after the drugmaker announced the results for two phase 3 trials testing VEGF Trap-Eye in wet AMD patients. The aptly named drug -- it sequesters a protein called VEGF in the eye, preventing blood vessel growth -- performed as well as Roche's Lucentis. But because it only has to be injected once every two months, instead of every month, VEGF Trap-Eye should have the advantage.

Regeneron and marketing partner Bayer plan to file applications to sell the drug in the U.S. and Europe in the first half of next year. Given the solid results, it seems extremely likely they'll get a green light.

The positive results don't necessarily mean Regeneron is an automatic buy, though; the company already sports a market cap of $2.5 billion, after all. Regeneron does have one drug on the market, Arcalyst , but it treats an ultra-orphan indication and has only managed to recognize $20 million in sales through the first nine months of the year. There's a fair amount of future sales already priced in and there's a long way to fall if things don't pan out.

Of course, like Human Genome Sciences (Nasdaq: HGSI) and Vertex Pharmaceuticals (Nasdaq: VRTX), which both have multibillion-dollar market caps despite not having drugs on the market, Regeneron has a lot of potential.

In addition to VEGF Trap-Eye, Regeneron has a sister compound, aflibercept, a version of VEGF Trap that prevents blood-vessel growth in solid tumors. Aflibercept, which is partnered with sanofi-aventis (NYSE: SNY), is in three phase 3 cancer trials that will play out over the next year. The potential market for aflibercept is much larger than for VEGF Trap-Eye; by comparison, sales of Roche's Avastin are about five times that of Lucentis. The fact that VEGF Trap-Eye works should give investors a little more confidence that aflibercept will, too, but it's by no means a sure thing.

Regeneron is also testing Arcalyst as a treatment for gout, which would vastly increase sales. Early results were mixed, but the drug still has time to redeem itself, with two additional phase 3 trials expected to produce results early next year.

At today's prices, Regeneron looks like a decent investment. There's still potential for a blowup, so don't put all your money in one basket, but there's still room to the upside even after yesterday's 20% run if aflibercept and Arcalyst pan out.

Anand Chokkavelu shares five investment lessons and five stocks to go along with them.

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Fool contributor Brian Orelli's grandmother had and grandfather has AMD. He's hoping to live long enough to get it. He doesn't own shares of any company mentioned in this article. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Fool has a disclosure policy.