Let's take a look at three stocks -- Orexigen Therapeutics (NASDAQ:OREX), Portola Pharmaceuticals (NASDAQ:PTLA), and Regeneron (NASDAQ:REGN) -- which could all loom large in Wednesday's health care headlines.

Orexigen's PDUFA date for NB32/Contrave gets extended by three months
Bad news for Orexigen this morning -- the FDA just extended its PDUFA (Prescription Drug User Fee Act) date for its obesity drug candidate NB32 three months to September 11, 2014. The FDA stated that it needed the extension to reach an agreement on Orexigen's post-marketing obligations and to further evaluate the drug's cardiovascular outcomes.

Investors should note that NB32, formerly known as Contrave, was rejected back in February 2011 due to concerns about statistically significant increases in blood pressure and heart rate.

The FDA has been fairly tough on new obesity drugs, after it pulled fen-phen (fenfluramine/phentermine) -- a popular weight loss treatment in the 1990s -- off the market in 1997 after it was implicated in potentially fatal pulmonary hypertension and heart valve problems. When two newer obesity drugs -- Arena's Belviq and VIVUS' Qsymia -- were approved in 2012, they were notably the first new obesity drugs approved by the FDA in 13 years.

Orexigen does not have any marketed products, and its pipeline only consists of two experimental drugs -- NB32 and Empatic, another weight loss treatment. Analysts once predicted that NB32/Contrave could generate peak sales of $1 billion, but those projections were set before its first rejection in 2011. Shares of Orexigen are down 17% in pre-market trading this morning.

Portola rallies on positive phase 2 results for andexanet alfa
Meanwhile, Portola Pharmaceuticals just announced positive phase 2 proof-of-concept study data for andexanet alfa, a potential first-in-class Factor Xa inhibitor antidote which reverses the effects of blood thinners.

Portola reports that andexanet alfa immediately reversed the anticoagulation activity of enoxaparin, a low molecular weight blood thinner commonly used to treat venous thromboembolisms. The company stated that the treatment was well tolerated with no adverse events reported. The trial was conducted on 27 healthy volunteers given either andexanet alfa or a placebo to reverse the effects of enoxaparin. Detailed data will be presented at the 60th Scientific and Standardization Committee (SSC) Meeting of the International Society of Thrombosis and Haemostasis (ISTH) from June 23 to 26.

Portola doesn't have any marketed products. Andexanet alfa is one of the company's two most advanced clinical products -- the other one is Betrixaban, a blood thinner. Portola currently holds collaborations with Pfizer, Bayer, Bristol-Myers Squibb, Johnson & Johnson, and Daiichi Sankyo for andexanet alfa.

Shares of Portola, which have already advanced 16% over the past 12 months, are currently up 7% in pre-market trading.

Label expansion for Eylea submitted to the EMA
Last but not least, Regeneron just reported that marketing partner Bayer (OTC:BAYRY) has submitted a marketing authorization application to the European Medicines Agency (EMA) for Eylea as a treatment for macular edema following branch retinal vein occlusion (BRVO).

Regeneron markets Eylea in the U.S. and Bayer markets the drug overseas and the companies split profits equally except for Japan, where Regeneron receives a percentage of net sales. Eylea is Regeneron's main source of revenue, accounting for more than two-thirds of its top line in 2013. Total worldwide sales of Eylea came in at nearly $1.9 billion last year, but it could still have room to climb -- analysts believe that the drug could eventually hit peak sales between $3.5 billion and $4.0 billion by 2020.

Eylea has been approved in the U.S. as a treatment for wet age-related macular degeneration (AMD) and for central retinal vein occlusion (CRVO). In Europe, it has been approved for wet AMD and macular edema following CRVO. Regulatory submissions have been made to the FDA for macular edema following BRVO and in Europe for diabetic macular edema (DME).

Of these indications, an approval for DME -- which affects 21 million people worldwide -- could be the biggest catalyst for Eylea sales, since the drug's primary competitor, Novartis' Lucentis, is currently approved to treat DME in the U.S. and Europe.

Shares of Regeneron remain unchanged in pre-market trading this morning. The stock has rallied 20% over the past 12 months.