What: After reporting fourth-quarter financial results yesterday and indicating today that it's initiating a late-stage trial for a key drug in its pipeline, Omeros Corporation (NASDAQ:OMER) is skyrocketing 17.5%.

So what: Omeros Corporation has one drug on the market, Omidria, a therapy for use in cataract and intraocular lens replacement procedures, and in the fourth quarter, sales grew 105% from the third quarter to $6.7 million.

Despite that growth, spending led to a loss of $19.8 million in the quarter, or $0.52 per share. Full-year results were similar. Omidria sales totaled $13.3 million since its launch in April 2015, but expenses more than dwarfed that figure, resulting in a full-year loss of $75 million, or $2 per share.

Management also indicated earlier today that its phase 3 trial of OMS721 for the treatment of atypical hemolytic uremic syndrome (aHUS) has kicked off. That's big news because, while aHUS is rare, it's currently treated with Alexion Pharmaceuticals' (NASDAQ:ALXN) Soliris, a drug that hauls in about $2.6 billion annually and growing.

Now what: Management has decided to bring its Omidria sales force in house and those 37 sales people, plus a potentially easing in reimbursement headwinds, has management thinking it can ramp Omidria sales this year.

A bigger opportunity, however, may exist if OMS721's trial pans out. Alexion Pharmaceutical's Soliris is the only FDA-approved therapy for aHUS and it carries a jaw-dropping sticker price of about $537,000 per year in the United States.

Omeros Corporation's OMS721 phase 3 trial will begin enrolling newly diagnosed aHUS patients later this year and the FDA appears willing to expedite the drug's development, agreeing to allow Omeros Corporation to use safety data across various indications, rather than in aHUS alone. Previously, the FDA awarded OMS721 both orphan drug designation and fast-track status, so its pathway to market is clearer than it may have been otherwise. Given the market opportunity, it's little wonder investors are bullish.

Editor's Note: This article has been updated to reflect 105% quarter-on-quarter growth, as opposed to 105% year-over-year growth, for Omidria sales. The Fool regrets the error.

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