19. Eylea

Regeneron and Bayer
Range of eye conditions
2015 sales: $2.46 billion
2020 projection: $4.04 billion

In November 2011, it was an FDA nod for Regeneron's ($REGN) Eylea in wet age-related macular degeneration that got the drug off to a blistering start, helping it trounce analyst estimates quarter after quarter.

These days, though, a different indication has been feeding much of the med's growth. Last February, Regeneron touted data showing that Eylea had bested Roche's ($RHHBY) eye med Lucentis and its Avastin--an oncology drug frequently used off-label in the eye--in patients with diabetic macular edema.

Those results helped power Eylea growth last year in the DME market; the therapy expanded by more than 50% in 2015. And currently, they're helping Eylea steal share from the pair of Roche offerings. Regeneron markets the drug in the states and collects a share from international partner Bayer.

But things are slowing down. The company forecasts 20% expansion for the blockbuster med in the U.S. this year. That 20% is "roughly in line" with consensus sales growth estimates of about 19% to 21%, according to Evercore ISI analyst Mark Schoenebaum. But shareholders--used to a breakneck pace from the eye therapy, which trounced sales estimate after sales estimate following its U.S. launch in late 2011--sent the company's stock price downward on the news. -- Carly Helfand (email | Twitter)

For more:
After a big 2015, Regeneron predicts slowing 2016 sales for launch superstar Eylea
DME data helps Eylea soar in Q2--and poach market share from its Roche rivals
Regeneron's Eylea beats Roche's Lucentis in new head-to-head study

19. Eylea