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What: Shares of biopharmaceutical companies Allergan (NYSE: AGN) and Regeneron Pharmaceuticals (NASDAQ:REGN) are heading in notably different directions today following an announcement from Allergan that data from its phase 2 study of vision-loss drug DARPin didn't support proceeding to late-stage trials. Allergan shares fell 15% on the news while Regeneron shares spiked as much as 17%.

So what: It's been a miserable day for Allergan, which started the day off by slightly lowering its full-year EPS forecast from a range of $4.75-$4.83 to $4.70-$4.76. To add the icing on the cake, its midday report that DARPin did show some differentiation from Novartis (NYSE:NVS) and Roche's (OTC:RHHBY) Lucentis but didn't demonstrate enough to move the drug onto phase 3 trials, sent Allergan into the abyss. It probably doesn't help, either, that MAP's inhaled migraine drug Levadex, which Allergan acquired when it purchased MAP for nearly $1 billion earlier this year, also recently received its second complete response letter. Allergan just can't seem to catch a break.

On the flipside, Regeneron shares are soaring on the news as DARPin would have been a direct competitor to its lead drug Eylea in terms of wet age-related macular degeneration. With DARPin's development delayed, Eylea has a chance to continue to grow sales at a tremendous pace. Deutsche Bank took the opportunity to boost its price target on Regeneron up to $310.

Now what: And this is precisely why I wanted Eylea as my lead drug candidate in my fantasy biotech draft! There really isn't a drug out there that's set to challenge Eylea's dominance in wet-AMD, and Eylea trumps Novartis and Roche's Lucentis on price, albeit marginally. For Allergan, it's been a disappointing day. More so, I'm growing concerned with two recent defeats to its development pipeline. While I do expect an eventual approval for Levadex, investors had been counting on DARPin to add to Allergan's impressive product portfolio. With DARPin now on hold, Allergan has lost a lot of its luster.

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